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TOMOYO Linux Cross Reference
Linux/mm/page_alloc.c

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  1 /*
  2  *  linux/mm/page_alloc.c
  3  *
  4  *  Manages the free list, the system allocates free pages here.
  5  *  Note that kmalloc() lives in slab.c
  6  *
  7  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  8  *  Swap reorganised 29.12.95, Stephen Tweedie
  9  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 10  *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
 11  *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 12  *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
 13  *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
 14  *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
 15  */
 16 
 17 #include <linux/stddef.h>
 18 #include <linux/mm.h>
 19 #include <linux/swap.h>
 20 #include <linux/interrupt.h>
 21 #include <linux/pagemap.h>
 22 #include <linux/jiffies.h>
 23 #include <linux/bootmem.h>
 24 #include <linux/memblock.h>
 25 #include <linux/compiler.h>
 26 #include <linux/kernel.h>
 27 #include <linux/kmemcheck.h>
 28 #include <linux/module.h>
 29 #include <linux/suspend.h>
 30 #include <linux/pagevec.h>
 31 #include <linux/blkdev.h>
 32 #include <linux/slab.h>
 33 #include <linux/ratelimit.h>
 34 #include <linux/oom.h>
 35 #include <linux/notifier.h>
 36 #include <linux/topology.h>
 37 #include <linux/sysctl.h>
 38 #include <linux/cpu.h>
 39 #include <linux/cpuset.h>
 40 #include <linux/memory_hotplug.h>
 41 #include <linux/nodemask.h>
 42 #include <linux/vmalloc.h>
 43 #include <linux/vmstat.h>
 44 #include <linux/mempolicy.h>
 45 #include <linux/stop_machine.h>
 46 #include <linux/sort.h>
 47 #include <linux/pfn.h>
 48 #include <linux/backing-dev.h>
 49 #include <linux/fault-inject.h>
 50 #include <linux/page-isolation.h>
 51 #include <linux/page_cgroup.h>
 52 #include <linux/debugobjects.h>
 53 #include <linux/kmemleak.h>
 54 #include <linux/memory.h>
 55 #include <linux/compaction.h>
 56 #include <trace/events/kmem.h>
 57 #include <linux/ftrace_event.h>
 58 #include <linux/memcontrol.h>
 59 #include <linux/prefetch.h>
 60 #include <linux/migrate.h>
 61 #include <linux/page-debug-flags.h>
 62 
 63 #include <asm/tlbflush.h>
 64 #include <asm/div64.h>
 65 #include "internal.h"
 66 
 67 #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
 68 DEFINE_PER_CPU(int, numa_node);
 69 EXPORT_PER_CPU_SYMBOL(numa_node);
 70 #endif
 71 
 72 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
 73 /*
 74  * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
 75  * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
 76  * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
 77  * defined in <linux/topology.h>.
 78  */
 79 DEFINE_PER_CPU(int, _numa_mem_);                /* Kernel "local memory" node */
 80 EXPORT_PER_CPU_SYMBOL(_numa_mem_);
 81 #endif
 82 
 83 /*
 84  * Array of node states.
 85  */
 86 nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
 87         [N_POSSIBLE] = NODE_MASK_ALL,
 88         [N_ONLINE] = { { [0] = 1UL } },
 89 #ifndef CONFIG_NUMA
 90         [N_NORMAL_MEMORY] = { { [0] = 1UL } },
 91 #ifdef CONFIG_HIGHMEM
 92         [N_HIGH_MEMORY] = { { [0] = 1UL } },
 93 #endif
 94         [N_CPU] = { { [0] = 1UL } },
 95 #endif  /* NUMA */
 96 };
 97 EXPORT_SYMBOL(node_states);
 98 
 99 unsigned long totalram_pages __read_mostly;
100 unsigned long totalreserve_pages __read_mostly;
101 /*
102  * When calculating the number of globally allowed dirty pages, there
103  * is a certain number of per-zone reserves that should not be
104  * considered dirtyable memory.  This is the sum of those reserves
105  * over all existing zones that contribute dirtyable memory.
106  */
107 unsigned long dirty_balance_reserve __read_mostly;
108 
109 int percpu_pagelist_fraction;
110 gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
111 
112 #ifdef CONFIG_PM_SLEEP
113 /*
114  * The following functions are used by the suspend/hibernate code to temporarily
115  * change gfp_allowed_mask in order to avoid using I/O during memory allocations
116  * while devices are suspended.  To avoid races with the suspend/hibernate code,
117  * they should always be called with pm_mutex held (gfp_allowed_mask also should
118  * only be modified with pm_mutex held, unless the suspend/hibernate code is
119  * guaranteed not to run in parallel with that modification).
120  */
121 
122 static gfp_t saved_gfp_mask;
123 
124 void pm_restore_gfp_mask(void)
125 {
126         WARN_ON(!mutex_is_locked(&pm_mutex));
127         if (saved_gfp_mask) {
128                 gfp_allowed_mask = saved_gfp_mask;
129                 saved_gfp_mask = 0;
130         }
131 }
132 
133 void pm_restrict_gfp_mask(void)
134 {
135         WARN_ON(!mutex_is_locked(&pm_mutex));
136         WARN_ON(saved_gfp_mask);
137         saved_gfp_mask = gfp_allowed_mask;
138         gfp_allowed_mask &= ~GFP_IOFS;
139 }
140 
141 bool pm_suspended_storage(void)
142 {
143         if ((gfp_allowed_mask & GFP_IOFS) == GFP_IOFS)
144                 return false;
145         return true;
146 }
147 #endif /* CONFIG_PM_SLEEP */
148 
149 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
150 int pageblock_order __read_mostly;
151 #endif
152 
153 static void __free_pages_ok(struct page *page, unsigned int order);
154 
155 /*
156  * results with 256, 32 in the lowmem_reserve sysctl:
157  *      1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
158  *      1G machine -> (16M dma, 784M normal, 224M high)
159  *      NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
160  *      HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
161  *      HIGHMEM allocation will (224M+784M)/256 of ram reserved in ZONE_DMA
162  *
163  * TBD: should special case ZONE_DMA32 machines here - in those we normally
164  * don't need any ZONE_NORMAL reservation
165  */
166 int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
167 #ifdef CONFIG_ZONE_DMA
168          256,
169 #endif
170 #ifdef CONFIG_ZONE_DMA32
171          256,
172 #endif
173 #ifdef CONFIG_HIGHMEM
174          32,
175 #endif
176          32,
177 };
178 
179 EXPORT_SYMBOL(totalram_pages);
180 
181 static char * const zone_names[MAX_NR_ZONES] = {
182 #ifdef CONFIG_ZONE_DMA
183          "DMA",
184 #endif
185 #ifdef CONFIG_ZONE_DMA32
186          "DMA32",
187 #endif
188          "Normal",
189 #ifdef CONFIG_HIGHMEM
190          "HighMem",
191 #endif
192          "Movable",
193 };
194 
195 int min_free_kbytes = 1024;
196 
197 static unsigned long __meminitdata nr_kernel_pages;
198 static unsigned long __meminitdata nr_all_pages;
199 static unsigned long __meminitdata dma_reserve;
200 
201 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
202 static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
203 static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
204 static unsigned long __initdata required_kernelcore;
205 static unsigned long __initdata required_movablecore;
206 static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
207 
208 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
209 int movable_zone;
210 EXPORT_SYMBOL(movable_zone);
211 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
212 
213 #if MAX_NUMNODES > 1
214 int nr_node_ids __read_mostly = MAX_NUMNODES;
215 int nr_online_nodes __read_mostly = 1;
216 EXPORT_SYMBOL(nr_node_ids);
217 EXPORT_SYMBOL(nr_online_nodes);
218 #endif
219 
220 int page_group_by_mobility_disabled __read_mostly;
221 
222 static void set_pageblock_migratetype(struct page *page, int migratetype)
223 {
224 
225         if (unlikely(page_group_by_mobility_disabled))
226                 migratetype = MIGRATE_UNMOVABLE;
227 
228         set_pageblock_flags_group(page, (unsigned long)migratetype,
229                                         PB_migrate, PB_migrate_end);
230 }
231 
232 bool oom_killer_disabled __read_mostly;
233 
234 #ifdef CONFIG_DEBUG_VM
235 static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
236 {
237         int ret = 0;
238         unsigned seq;
239         unsigned long pfn = page_to_pfn(page);
240 
241         do {
242                 seq = zone_span_seqbegin(zone);
243                 if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
244                         ret = 1;
245                 else if (pfn < zone->zone_start_pfn)
246                         ret = 1;
247         } while (zone_span_seqretry(zone, seq));
248 
249         return ret;
250 }
251 
252 static int page_is_consistent(struct zone *zone, struct page *page)
253 {
254         if (!pfn_valid_within(page_to_pfn(page)))
255                 return 0;
256         if (zone != page_zone(page))
257                 return 0;
258 
259         return 1;
260 }
261 /*
262  * Temporary debugging check for pages not lying within a given zone.
263  */
264 static int bad_range(struct zone *zone, struct page *page)
265 {
266         if (page_outside_zone_boundaries(zone, page))
267                 return 1;
268         if (!page_is_consistent(zone, page))
269                 return 1;
270 
271         return 0;
272 }
273 #else
274 static inline int bad_range(struct zone *zone, struct page *page)
275 {
276         return 0;
277 }
278 #endif
279 
280 static void bad_page(struct page *page)
281 {
282         static unsigned long resume;
283         static unsigned long nr_shown;
284         static unsigned long nr_unshown;
285 
286         /* Don't complain about poisoned pages */
287         if (PageHWPoison(page)) {
288                 reset_page_mapcount(page); /* remove PageBuddy */
289                 return;
290         }
291 
292         /*
293          * Allow a burst of 60 reports, then keep quiet for that minute;
294          * or allow a steady drip of one report per second.
295          */
296         if (nr_shown == 60) {
297                 if (time_before(jiffies, resume)) {
298                         nr_unshown++;
299                         goto out;
300                 }
301                 if (nr_unshown) {
302                         printk(KERN_ALERT
303                               "BUG: Bad page state: %lu messages suppressed\n",
304                                 nr_unshown);
305                         nr_unshown = 0;
306                 }
307                 nr_shown = 0;
308         }
309         if (nr_shown++ == 0)
310                 resume = jiffies + 60 * HZ;
311 
312         printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
313                 current->comm, page_to_pfn(page));
314         dump_page(page);
315 
316         print_modules();
317         dump_stack();
318 out:
319         /* Leave bad fields for debug, except PageBuddy could make trouble */
320         reset_page_mapcount(page); /* remove PageBuddy */
321         add_taint(TAINT_BAD_PAGE);
322 }
323 
324 /*
325  * Higher-order pages are called "compound pages".  They are structured thusly:
326  *
327  * The first PAGE_SIZE page is called the "head page".
328  *
329  * The remaining PAGE_SIZE pages are called "tail pages".
330  *
331  * All pages have PG_compound set.  All tail pages have their ->first_page
332  * pointing at the head page.
333  *
334  * The first tail page's ->lru.next holds the address of the compound page's
335  * put_page() function.  Its ->lru.prev holds the order of allocation.
336  * This usage means that zero-order pages may not be compound.
337  */
338 
339 static void free_compound_page(struct page *page)
340 {
341         __free_pages_ok(page, compound_order(page));
342 }
343 
344 void prep_compound_page(struct page *page, unsigned long order)
345 {
346         int i;
347         int nr_pages = 1 << order;
348 
349         set_compound_page_dtor(page, free_compound_page);
350         set_compound_order(page, order);
351         __SetPageHead(page);
352         for (i = 1; i < nr_pages; i++) {
353                 struct page *p = page + i;
354                 __SetPageTail(p);
355                 set_page_count(p, 0);
356                 p->first_page = page;
357         }
358 }
359 
360 /* update __split_huge_page_refcount if you change this function */
361 static int destroy_compound_page(struct page *page, unsigned long order)
362 {
363         int i;
364         int nr_pages = 1 << order;
365         int bad = 0;
366 
367         if (unlikely(compound_order(page) != order) ||
368             unlikely(!PageHead(page))) {
369                 bad_page(page);
370                 bad++;
371         }
372 
373         __ClearPageHead(page);
374 
375         for (i = 1; i < nr_pages; i++) {
376                 struct page *p = page + i;
377 
378                 if (unlikely(!PageTail(p) || (p->first_page != page))) {
379                         bad_page(page);
380                         bad++;
381                 }
382                 __ClearPageTail(p);
383         }
384 
385         return bad;
386 }
387 
388 static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
389 {
390         int i;
391 
392         /*
393          * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
394          * and __GFP_HIGHMEM from hard or soft interrupt context.
395          */
396         VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
397         for (i = 0; i < (1 << order); i++)
398                 clear_highpage(page + i);
399 }
400 
401 #ifdef CONFIG_DEBUG_PAGEALLOC
402 unsigned int _debug_guardpage_minorder;
403 
404 static int __init debug_guardpage_minorder_setup(char *buf)
405 {
406         unsigned long res;
407 
408         if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
409                 printk(KERN_ERR "Bad debug_guardpage_minorder value\n");
410                 return 0;
411         }
412         _debug_guardpage_minorder = res;
413         printk(KERN_INFO "Setting debug_guardpage_minorder to %lu\n", res);
414         return 0;
415 }
416 __setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
417 
418 static inline void set_page_guard_flag(struct page *page)
419 {
420         __set_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
421 }
422 
423 static inline void clear_page_guard_flag(struct page *page)
424 {
425         __clear_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
426 }
427 #else
428 static inline void set_page_guard_flag(struct page *page) { }
429 static inline void clear_page_guard_flag(struct page *page) { }
430 #endif
431 
432 static inline void set_page_order(struct page *page, int order)
433 {
434         set_page_private(page, order);
435         __SetPageBuddy(page);
436 }
437 
438 static inline void rmv_page_order(struct page *page)
439 {
440         __ClearPageBuddy(page);
441         set_page_private(page, 0);
442 }
443 
444 /*
445  * Locate the struct page for both the matching buddy in our
446  * pair (buddy1) and the combined O(n+1) page they form (page).
447  *
448  * 1) Any buddy B1 will have an order O twin B2 which satisfies
449  * the following equation:
450  *     B2 = B1 ^ (1 << O)
451  * For example, if the starting buddy (buddy2) is #8 its order
452  * 1 buddy is #10:
453  *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
454  *
455  * 2) Any buddy B will have an order O+1 parent P which
456  * satisfies the following equation:
457  *     P = B & ~(1 << O)
458  *
459  * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
460  */
461 static inline unsigned long
462 __find_buddy_index(unsigned long page_idx, unsigned int order)
463 {
464         return page_idx ^ (1 << order);
465 }
466 
467 /*
468  * This function checks whether a page is free && is the buddy
469  * we can do coalesce a page and its buddy if
470  * (a) the buddy is not in a hole &&
471  * (b) the buddy is in the buddy system &&
472  * (c) a page and its buddy have the same order &&
473  * (d) a page and its buddy are in the same zone.
474  *
475  * For recording whether a page is in the buddy system, we set ->_mapcount -2.
476  * Setting, clearing, and testing _mapcount -2 is serialized by zone->lock.
477  *
478  * For recording page's order, we use page_private(page).
479  */
480 static inline int page_is_buddy(struct page *page, struct page *buddy,
481                                                                 int order)
482 {
483         if (!pfn_valid_within(page_to_pfn(buddy)))
484                 return 0;
485 
486         if (page_zone_id(page) != page_zone_id(buddy))
487                 return 0;
488 
489         if (page_is_guard(buddy) && page_order(buddy) == order) {
490                 VM_BUG_ON(page_count(buddy) != 0);
491                 return 1;
492         }
493 
494         if (PageBuddy(buddy) && page_order(buddy) == order) {
495                 VM_BUG_ON(page_count(buddy) != 0);
496                 return 1;
497         }
498         return 0;
499 }
500 
501 /*
502  * Freeing function for a buddy system allocator.
503  *
504  * The concept of a buddy system is to maintain direct-mapped table
505  * (containing bit values) for memory blocks of various "orders".
506  * The bottom level table contains the map for the smallest allocatable
507  * units of memory (here, pages), and each level above it describes
508  * pairs of units from the levels below, hence, "buddies".
509  * At a high level, all that happens here is marking the table entry
510  * at the bottom level available, and propagating the changes upward
511  * as necessary, plus some accounting needed to play nicely with other
512  * parts of the VM system.
513  * At each level, we keep a list of pages, which are heads of continuous
514  * free pages of length of (1 << order) and marked with _mapcount -2. Page's
515  * order is recorded in page_private(page) field.
516  * So when we are allocating or freeing one, we can derive the state of the
517  * other.  That is, if we allocate a small block, and both were
518  * free, the remainder of the region must be split into blocks.
519  * If a block is freed, and its buddy is also free, then this
520  * triggers coalescing into a block of larger size.
521  *
522  * -- wli
523  */
524 
525 static inline void __free_one_page(struct page *page,
526                 struct zone *zone, unsigned int order,
527                 int migratetype)
528 {
529         unsigned long page_idx;
530         unsigned long combined_idx;
531         unsigned long uninitialized_var(buddy_idx);
532         struct page *buddy;
533 
534         if (unlikely(PageCompound(page)))
535                 if (unlikely(destroy_compound_page(page, order)))
536                         return;
537 
538         VM_BUG_ON(migratetype == -1);
539 
540         page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
541 
542         VM_BUG_ON(page_idx & ((1 << order) - 1));
543         VM_BUG_ON(bad_range(zone, page));
544 
545         while (order < MAX_ORDER-1) {
546                 buddy_idx = __find_buddy_index(page_idx, order);
547                 buddy = page + (buddy_idx - page_idx);
548                 if (!page_is_buddy(page, buddy, order))
549                         break;
550                 /*
551                  * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
552                  * merge with it and move up one order.
553                  */
554                 if (page_is_guard(buddy)) {
555                         clear_page_guard_flag(buddy);
556                         set_page_private(page, 0);
557                         __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
558                 } else {
559                         list_del(&buddy->lru);
560                         zone->free_area[order].nr_free--;
561                         rmv_page_order(buddy);
562                 }
563                 combined_idx = buddy_idx & page_idx;
564                 page = page + (combined_idx - page_idx);
565                 page_idx = combined_idx;
566                 order++;
567         }
568         set_page_order(page, order);
569 
570         /*
571          * If this is not the largest possible page, check if the buddy
572          * of the next-highest order is free. If it is, it's possible
573          * that pages are being freed that will coalesce soon. In case,
574          * that is happening, add the free page to the tail of the list
575          * so it's less likely to be used soon and more likely to be merged
576          * as a higher order page
577          */
578         if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) {
579                 struct page *higher_page, *higher_buddy;
580                 combined_idx = buddy_idx & page_idx;
581                 higher_page = page + (combined_idx - page_idx);
582                 buddy_idx = __find_buddy_index(combined_idx, order + 1);
583                 higher_buddy = higher_page + (buddy_idx - combined_idx);
584                 if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
585                         list_add_tail(&page->lru,
586                                 &zone->free_area[order].free_list[migratetype]);
587                         goto out;
588                 }
589         }
590 
591         list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
592 out:
593         zone->free_area[order].nr_free++;
594 }
595 
596 /*
597  * free_page_mlock() -- clean up attempts to free and mlocked() page.
598  * Page should not be on lru, so no need to fix that up.
599  * free_pages_check() will verify...
600  */
601 static inline void free_page_mlock(struct page *page)
602 {
603         __dec_zone_page_state(page, NR_MLOCK);
604         __count_vm_event(UNEVICTABLE_MLOCKFREED);
605 }
606 
607 static inline int free_pages_check(struct page *page)
608 {
609         if (unlikely(page_mapcount(page) |
610                 (page->mapping != NULL)  |
611                 (atomic_read(&page->_count) != 0) |
612                 (page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
613                 (mem_cgroup_bad_page_check(page)))) {
614                 bad_page(page);
615                 return 1;
616         }
617         if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
618                 page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
619         return 0;
620 }
621 
622 /*
623  * Frees a number of pages from the PCP lists
624  * Assumes all pages on list are in same zone, and of same order.
625  * count is the number of pages to free.
626  *
627  * If the zone was previously in an "all pages pinned" state then look to
628  * see if this freeing clears that state.
629  *
630  * And clear the zone's pages_scanned counter, to hold off the "all pages are
631  * pinned" detection logic.
632  */
633 static void free_pcppages_bulk(struct zone *zone, int count,
634                                         struct per_cpu_pages *pcp)
635 {
636         int migratetype = 0;
637         int batch_free = 0;
638         int to_free = count;
639 
640         spin_lock(&zone->lock);
641         zone->all_unreclaimable = 0;
642         zone->pages_scanned = 0;
643 
644         while (to_free) {
645                 struct page *page;
646                 struct list_head *list;
647 
648                 /*
649                  * Remove pages from lists in a round-robin fashion. A
650                  * batch_free count is maintained that is incremented when an
651                  * empty list is encountered.  This is so more pages are freed
652                  * off fuller lists instead of spinning excessively around empty
653                  * lists
654                  */
655                 do {
656                         batch_free++;
657                         if (++migratetype == MIGRATE_PCPTYPES)
658                                 migratetype = 0;
659                         list = &pcp->lists[migratetype];
660                 } while (list_empty(list));
661 
662                 /* This is the only non-empty list. Free them all. */
663                 if (batch_free == MIGRATE_PCPTYPES)
664                         batch_free = to_free;
665 
666                 do {
667                         page = list_entry(list->prev, struct page, lru);
668                         /* must delete as __free_one_page list manipulates */
669                         list_del(&page->lru);
670                         /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
671                         __free_one_page(page, zone, 0, page_private(page));
672                         trace_mm_page_pcpu_drain(page, 0, page_private(page));
673                 } while (--to_free && --batch_free && !list_empty(list));
674         }
675         __mod_zone_page_state(zone, NR_FREE_PAGES, count);
676         spin_unlock(&zone->lock);
677 }
678 
679 static void free_one_page(struct zone *zone, struct page *page, int order,
680                                 int migratetype)
681 {
682         spin_lock(&zone->lock);
683         zone->all_unreclaimable = 0;
684         zone->pages_scanned = 0;
685 
686         __free_one_page(page, zone, order, migratetype);
687         __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
688         spin_unlock(&zone->lock);
689 }
690 
691 static bool free_pages_prepare(struct page *page, unsigned int order)
692 {
693         int i;
694         int bad = 0;
695 
696         trace_mm_page_free(page, order);
697         kmemcheck_free_shadow(page, order);
698 
699         if (PageAnon(page))
700                 page->mapping = NULL;
701         for (i = 0; i < (1 << order); i++)
702                 bad += free_pages_check(page + i);
703         if (bad)
704                 return false;
705 
706         if (!PageHighMem(page)) {
707                 debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
708                 debug_check_no_obj_freed(page_address(page),
709                                            PAGE_SIZE << order);
710         }
711         arch_free_page(page, order);
712         kernel_map_pages(page, 1 << order, 0);
713 
714         return true;
715 }
716 
717 static void __free_pages_ok(struct page *page, unsigned int order)
718 {
719         unsigned long flags;
720         int wasMlocked = __TestClearPageMlocked(page);
721 
722         if (!free_pages_prepare(page, order))
723                 return;
724 
725         local_irq_save(flags);
726         if (unlikely(wasMlocked))
727                 free_page_mlock(page);
728         __count_vm_events(PGFREE, 1 << order);
729         free_one_page(page_zone(page), page, order,
730                                         get_pageblock_migratetype(page));
731         local_irq_restore(flags);
732 }
733 
734 void __meminit __free_pages_bootmem(struct page *page, unsigned int order)
735 {
736         unsigned int nr_pages = 1 << order;
737         unsigned int loop;
738 
739         prefetchw(page);
740         for (loop = 0; loop < nr_pages; loop++) {
741                 struct page *p = &page[loop];
742 
743                 if (loop + 1 < nr_pages)
744                         prefetchw(p + 1);
745                 __ClearPageReserved(p);
746                 set_page_count(p, 0);
747         }
748 
749         set_page_refcounted(page);
750         __free_pages(page, order);
751 }
752 
753 #ifdef CONFIG_CMA
754 /* Free whole pageblock and set it's migration type to MIGRATE_CMA. */
755 void __init init_cma_reserved_pageblock(struct page *page)
756 {
757         unsigned i = pageblock_nr_pages;
758         struct page *p = page;
759 
760         do {
761                 __ClearPageReserved(p);
762                 set_page_count(p, 0);
763         } while (++p, --i);
764 
765         set_page_refcounted(page);
766         set_pageblock_migratetype(page, MIGRATE_CMA);
767         __free_pages(page, pageblock_order);
768         totalram_pages += pageblock_nr_pages;
769 }
770 #endif
771 
772 /*
773  * The order of subdivision here is critical for the IO subsystem.
774  * Please do not alter this order without good reasons and regression
775  * testing. Specifically, as large blocks of memory are subdivided,
776  * the order in which smaller blocks are delivered depends on the order
777  * they're subdivided in this function. This is the primary factor
778  * influencing the order in which pages are delivered to the IO
779  * subsystem according to empirical testing, and this is also justified
780  * by considering the behavior of a buddy system containing a single
781  * large block of memory acted on by a series of small allocations.
782  * This behavior is a critical factor in sglist merging's success.
783  *
784  * -- wli
785  */
786 static inline void expand(struct zone *zone, struct page *page,
787         int low, int high, struct free_area *area,
788         int migratetype)
789 {
790         unsigned long size = 1 << high;
791 
792         while (high > low) {
793                 area--;
794                 high--;
795                 size >>= 1;
796                 VM_BUG_ON(bad_range(zone, &page[size]));
797 
798 #ifdef CONFIG_DEBUG_PAGEALLOC
799                 if (high < debug_guardpage_minorder()) {
800                         /*
801                          * Mark as guard pages (or page), that will allow to
802                          * merge back to allocator when buddy will be freed.
803                          * Corresponding page table entries will not be touched,
804                          * pages will stay not present in virtual address space
805                          */
806                         INIT_LIST_HEAD(&page[size].lru);
807                         set_page_guard_flag(&page[size]);
808                         set_page_private(&page[size], high);
809                         /* Guard pages are not available for any usage */
810                         __mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << high));
811                         continue;
812                 }
813 #endif
814                 list_add(&page[size].lru, &area->free_list[migratetype]);
815                 area->nr_free++;
816                 set_page_order(&page[size], high);
817         }
818 }
819 
820 /*
821  * This page is about to be returned from the page allocator
822  */
823 static inline int check_new_page(struct page *page)
824 {
825         if (unlikely(page_mapcount(page) |
826                 (page->mapping != NULL)  |
827                 (atomic_read(&page->_count) != 0)  |
828                 (page->flags & PAGE_FLAGS_CHECK_AT_PREP) |
829                 (mem_cgroup_bad_page_check(page)))) {
830                 bad_page(page);
831                 return 1;
832         }
833         return 0;
834 }
835 
836 static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
837 {
838         int i;
839 
840         for (i = 0; i < (1 << order); i++) {
841                 struct page *p = page + i;
842                 if (unlikely(check_new_page(p)))
843                         return 1;
844         }
845 
846         set_page_private(page, 0);
847         set_page_refcounted(page);
848 
849         arch_alloc_page(page, order);
850         kernel_map_pages(page, 1 << order, 1);
851 
852         if (gfp_flags & __GFP_ZERO)
853                 prep_zero_page(page, order, gfp_flags);
854 
855         if (order && (gfp_flags & __GFP_COMP))
856                 prep_compound_page(page, order);
857 
858         return 0;
859 }
860 
861 /*
862  * Go through the free lists for the given migratetype and remove
863  * the smallest available page from the freelists
864  */
865 static inline
866 struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
867                                                 int migratetype)
868 {
869         unsigned int current_order;
870         struct free_area * area;
871         struct page *page;
872 
873         /* Find a page of the appropriate size in the preferred list */
874         for (current_order = order; current_order < MAX_ORDER; ++current_order) {
875                 area = &(zone->free_area[current_order]);
876                 if (list_empty(&area->free_list[migratetype]))
877                         continue;
878 
879                 page = list_entry(area->free_list[migratetype].next,
880                                                         struct page, lru);
881                 list_del(&page->lru);
882                 rmv_page_order(page);
883                 area->nr_free--;
884                 expand(zone, page, order, current_order, area, migratetype);
885                 return page;
886         }
887 
888         return NULL;
889 }
890 
891 
892 /*
893  * This array describes the order lists are fallen back to when
894  * the free lists for the desirable migrate type are depleted
895  */
896 static int fallbacks[MIGRATE_TYPES][4] = {
897         [MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,     MIGRATE_RESERVE },
898         [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,     MIGRATE_RESERVE },
899 #ifdef CONFIG_CMA
900         [MIGRATE_MOVABLE]     = { MIGRATE_CMA,         MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
901         [MIGRATE_CMA]         = { MIGRATE_RESERVE }, /* Never used */
902 #else
903         [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,   MIGRATE_RESERVE },
904 #endif
905         [MIGRATE_RESERVE]     = { MIGRATE_RESERVE }, /* Never used */
906         [MIGRATE_ISOLATE]     = { MIGRATE_RESERVE }, /* Never used */
907 };
908 
909 /*
910  * Move the free pages in a range to the free lists of the requested type.
911  * Note that start_page and end_pages are not aligned on a pageblock
912  * boundary. If alignment is required, use move_freepages_block()
913  */
914 static int move_freepages(struct zone *zone,
915                           struct page *start_page, struct page *end_page,
916                           int migratetype)
917 {
918         struct page *page;
919         unsigned long order;
920         int pages_moved = 0;
921 
922 #ifndef CONFIG_HOLES_IN_ZONE
923         /*
924          * page_zone is not safe to call in this context when
925          * CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant
926          * anyway as we check zone boundaries in move_freepages_block().
927          * Remove at a later date when no bug reports exist related to
928          * grouping pages by mobility
929          */
930         BUG_ON(page_zone(start_page) != page_zone(end_page));
931 #endif
932 
933         for (page = start_page; page <= end_page;) {
934                 /* Make sure we are not inadvertently changing nodes */
935                 VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));
936 
937                 if (!pfn_valid_within(page_to_pfn(page))) {
938                         page++;
939                         continue;
940                 }
941 
942                 if (!PageBuddy(page)) {
943                         page++;
944                         continue;
945                 }
946 
947                 order = page_order(page);
948                 list_move(&page->lru,
949                           &zone->free_area[order].free_list[migratetype]);
950                 page += 1 << order;
951                 pages_moved += 1 << order;
952         }
953 
954         return pages_moved;
955 }
956 
957 static int move_freepages_block(struct zone *zone, struct page *page,
958                                 int migratetype)
959 {
960         unsigned long start_pfn, end_pfn;
961         struct page *start_page, *end_page;
962 
963         start_pfn = page_to_pfn(page);
964         start_pfn = start_pfn & ~(pageblock_nr_pages-1);
965         start_page = pfn_to_page(start_pfn);
966         end_page = start_page + pageblock_nr_pages - 1;
967         end_pfn = start_pfn + pageblock_nr_pages - 1;
968 
969         /* Do not cross zone boundaries */
970         if (start_pfn < zone->zone_start_pfn)
971                 start_page = page;
972         if (end_pfn >= zone->zone_start_pfn + zone->spanned_pages)
973                 return 0;
974 
975         return move_freepages(zone, start_page, end_page, migratetype);
976 }
977 
978 static void change_pageblock_range(struct page *pageblock_page,
979                                         int start_order, int migratetype)
980 {
981         int nr_pageblocks = 1 << (start_order - pageblock_order);
982 
983         while (nr_pageblocks--) {
984                 set_pageblock_migratetype(pageblock_page, migratetype);
985                 pageblock_page += pageblock_nr_pages;
986         }
987 }
988 
989 /* Remove an element from the buddy allocator from the fallback list */
990 static inline struct page *
991 __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
992 {
993         struct free_area * area;
994         int current_order;
995         struct page *page;
996         int migratetype, i;
997 
998         /* Find the largest possible block of pages in the other list */
999         for (current_order = MAX_ORDER-1; current_order >= order;
1000                                                 --current_order) {
1001                 for (i = 0;; i++) {
1002                         migratetype = fallbacks[start_migratetype][i];
1003 
1004                         /* MIGRATE_RESERVE handled later if necessary */
1005                         if (migratetype == MIGRATE_RESERVE)
1006                                 break;
1007 
1008                         area = &(zone->free_area[current_order]);
1009                         if (list_empty(&area->free_list[migratetype]))
1010                                 continue;
1011 
1012                         page = list_entry(area->free_list[migratetype].next,
1013                                         struct page, lru);
1014                         area->nr_free--;
1015 
1016                         /*
1017                          * If breaking a large block of pages, move all free
1018                          * pages to the preferred allocation list. If falling
1019                          * back for a reclaimable kernel allocation, be more
1020                          * aggressive about taking ownership of free pages
1021                          *
1022                          * On the other hand, never change migration
1023                          * type of MIGRATE_CMA pageblocks nor move CMA
1024                          * pages on different free lists. We don't
1025                          * want unmovable pages to be allocated from
1026                          * MIGRATE_CMA areas.
1027                          */
1028                         if (!is_migrate_cma(migratetype) &&
1029                             (unlikely(current_order >= pageblock_order / 2) ||
1030                              start_migratetype == MIGRATE_RECLAIMABLE ||
1031                              page_group_by_mobility_disabled)) {
1032                                 int pages;
1033                                 pages = move_freepages_block(zone, page,
1034                                                                 start_migratetype);
1035 
1036                                 /* Claim the whole block if over half of it is free */
1037                                 if (pages >= (1 << (pageblock_order-1)) ||
1038                                                 page_group_by_mobility_disabled)
1039                                         set_pageblock_migratetype(page,
1040                                                                 start_migratetype);
1041 
1042                                 migratetype = start_migratetype;
1043                         }
1044 
1045                         /* Remove the page from the freelists */
1046                         list_del(&page->lru);
1047                         rmv_page_order(page);
1048 
1049                         /* Take ownership for orders >= pageblock_order */
1050                         if (current_order >= pageblock_order &&
1051                             !is_migrate_cma(migratetype))
1052                                 change_pageblock_range(page, current_order,
1053                                                         start_migratetype);
1054 
1055                         expand(zone, page, order, current_order, area,
1056                                is_migrate_cma(migratetype)
1057                              ? migratetype : start_migratetype);
1058 
1059                         trace_mm_page_alloc_extfrag(page, order, current_order,
1060                                 start_migratetype, migratetype);
1061 
1062                         return page;
1063                 }
1064         }
1065 
1066         return NULL;
1067 }
1068 
1069 /*
1070  * Do the hard work of removing an element from the buddy allocator.
1071  * Call me with the zone->lock already held.
1072  */
1073 static struct page *__rmqueue(struct zone *zone, unsigned int order,
1074                                                 int migratetype)
1075 {
1076         struct page *page;
1077 
1078 retry_reserve:
1079         page = __rmqueue_smallest(zone, order, migratetype);
1080 
1081         if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
1082                 page = __rmqueue_fallback(zone, order, migratetype);
1083 
1084                 /*
1085                  * Use MIGRATE_RESERVE rather than fail an allocation. goto
1086                  * is used because __rmqueue_smallest is an inline function
1087                  * and we want just one call site
1088                  */
1089                 if (!page) {
1090                         migratetype = MIGRATE_RESERVE;
1091                         goto retry_reserve;
1092                 }
1093         }
1094 
1095         trace_mm_page_alloc_zone_locked(page, order, migratetype);
1096         return page;
1097 }
1098 
1099 /*
1100  * Obtain a specified number of elements from the buddy allocator, all under
1101  * a single hold of the lock, for efficiency.  Add them to the supplied list.
1102  * Returns the number of new pages which were placed at *list.
1103  */
1104 static int rmqueue_bulk(struct zone *zone, unsigned int order,
1105                         unsigned long count, struct list_head *list,
1106                         int migratetype, int cold)
1107 {
1108         int mt = migratetype, i;
1109 
1110         spin_lock(&zone->lock);
1111         for (i = 0; i < count; ++i) {
1112                 struct page *page = __rmqueue(zone, order, migratetype);
1113                 if (unlikely(page == NULL))
1114                         break;
1115 
1116                 /*
1117                  * Split buddy pages returned by expand() are received here
1118                  * in physical page order. The page is added to the callers and
1119                  * list and the list head then moves forward. From the callers
1120                  * perspective, the linked list is ordered by page number in
1121                  * some conditions. This is useful for IO devices that can
1122                  * merge IO requests if the physical pages are ordered
1123                  * properly.
1124                  */
1125                 if (likely(cold == 0))
1126                         list_add(&page->lru, list);
1127                 else
1128                         list_add_tail(&page->lru, list);
1129                 if (IS_ENABLED(CONFIG_CMA)) {
1130                         mt = get_pageblock_migratetype(page);
1131                         if (!is_migrate_cma(mt) && mt != MIGRATE_ISOLATE)
1132                                 mt = migratetype;
1133                 }
1134                 set_page_private(page, mt);
1135                 list = &page->lru;
1136         }
1137         __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
1138         spin_unlock(&zone->lock);
1139         return i;
1140 }
1141 
1142 #ifdef CONFIG_NUMA
1143 /*
1144  * Called from the vmstat counter updater to drain pagesets of this
1145  * currently executing processor on remote nodes after they have
1146  * expired.
1147  *
1148  * Note that this function must be called with the thread pinned to
1149  * a single processor.
1150  */
1151 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
1152 {
1153         unsigned long flags;
1154         int to_drain;
1155 
1156         local_irq_save(flags);
1157         if (pcp->count >= pcp->batch)
1158                 to_drain = pcp->batch;
1159         else
1160                 to_drain = pcp->count;
1161         free_pcppages_bulk(zone, to_drain, pcp);
1162         pcp->count -= to_drain;
1163         local_irq_restore(flags);
1164 }
1165 #endif
1166 
1167 /*
1168  * Drain pages of the indicated processor.
1169  *
1170  * The processor must either be the current processor and the
1171  * thread pinned to the current processor or a processor that
1172  * is not online.
1173  */
1174 static void drain_pages(unsigned int cpu)
1175 {
1176         unsigned long flags;
1177         struct zone *zone;
1178 
1179         for_each_populated_zone(zone) {
1180                 struct per_cpu_pageset *pset;
1181                 struct per_cpu_pages *pcp;
1182 
1183                 local_irq_save(flags);
1184                 pset = per_cpu_ptr(zone->pageset, cpu);
1185 
1186                 pcp = &pset->pcp;
1187                 if (pcp->count) {
1188                         free_pcppages_bulk(zone, pcp->count, pcp);
1189                         pcp->count = 0;
1190                 }
1191                 local_irq_restore(flags);
1192         }
1193 }
1194 
1195 /*
1196  * Spill all of this CPU's per-cpu pages back into the buddy allocator.
1197  */
1198 void drain_local_pages(void *arg)
1199 {
1200         drain_pages(smp_processor_id());
1201 }
1202 
1203 /*
1204  * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
1205  *
1206  * Note that this code is protected against sending an IPI to an offline
1207  * CPU but does not guarantee sending an IPI to newly hotplugged CPUs:
1208  * on_each_cpu_mask() blocks hotplug and won't talk to offlined CPUs but
1209  * nothing keeps CPUs from showing up after we populated the cpumask and
1210  * before the call to on_each_cpu_mask().
1211  */
1212 void drain_all_pages(void)
1213 {
1214         int cpu;
1215         struct per_cpu_pageset *pcp;
1216         struct zone *zone;
1217 
1218         /*
1219          * Allocate in the BSS so we wont require allocation in
1220          * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
1221          */
1222         static cpumask_t cpus_with_pcps;
1223 
1224         /*
1225          * We don't care about racing with CPU hotplug event
1226          * as offline notification will cause the notified
1227          * cpu to drain that CPU pcps and on_each_cpu_mask
1228          * disables preemption as part of its processing
1229          */
1230         for_each_online_cpu(cpu) {
1231                 bool has_pcps = false;
1232                 for_each_populated_zone(zone) {
1233                         pcp = per_cpu_ptr(zone->pageset, cpu);
1234                         if (pcp->pcp.count) {
1235                                 has_pcps = true;
1236                                 break;
1237                         }
1238                 }
1239                 if (has_pcps)
1240                         cpumask_set_cpu(cpu, &cpus_with_pcps);
1241                 else
1242                         cpumask_clear_cpu(cpu, &cpus_with_pcps);
1243         }
1244         on_each_cpu_mask(&cpus_with_pcps, drain_local_pages, NULL, 1);
1245 }
1246 
1247 #ifdef CONFIG_HIBERNATION
1248 
1249 void mark_free_pages(struct zone *zone)
1250 {
1251         unsigned long pfn, max_zone_pfn;
1252         unsigned long flags;
1253         int order, t;
1254         struct list_head *curr;
1255 
1256         if (!zone->spanned_pages)
1257                 return;
1258 
1259         spin_lock_irqsave(&zone->lock, flags);
1260 
1261         max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
1262         for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
1263                 if (pfn_valid(pfn)) {
1264                         struct page *page = pfn_to_page(pfn);
1265 
1266                         if (!swsusp_page_is_forbidden(page))
1267                                 swsusp_unset_page_free(page);
1268                 }
1269 
1270         for_each_migratetype_order(order, t) {
1271                 list_for_each(curr, &zone->free_area[order].free_list[t]) {
1272                         unsigned long i;
1273 
1274                         pfn = page_to_pfn(list_entry(curr, struct page, lru));
1275                         for (i = 0; i < (1UL << order); i++)
1276                                 swsusp_set_page_free(pfn_to_page(pfn + i));
1277                 }
1278         }
1279         spin_unlock_irqrestore(&zone->lock, flags);
1280 }
1281 #endif /* CONFIG_PM */
1282 
1283 /*
1284  * Free a 0-order page
1285  * cold == 1 ? free a cold page : free a hot page
1286  */
1287 void free_hot_cold_page(struct page *page, int cold)
1288 {
1289         struct zone *zone = page_zone(page);
1290         struct per_cpu_pages *pcp;
1291         unsigned long flags;
1292         int migratetype;
1293         int wasMlocked = __TestClearPageMlocked(page);
1294 
1295         if (!free_pages_prepare(page, 0))
1296                 return;
1297 
1298         migratetype = get_pageblock_migratetype(page);
1299         set_page_private(page, migratetype);
1300         local_irq_save(flags);
1301         if (unlikely(wasMlocked))
1302                 free_page_mlock(page);
1303         __count_vm_event(PGFREE);
1304 
1305         /*
1306          * We only track unmovable, reclaimable and movable on pcp lists.
1307          * Free ISOLATE pages back to the allocator because they are being
1308          * offlined but treat RESERVE as movable pages so we can get those
1309          * areas back if necessary. Otherwise, we may have to free
1310          * excessively into the page allocator
1311          */
1312         if (migratetype >= MIGRATE_PCPTYPES) {
1313                 if (unlikely(migratetype == MIGRATE_ISOLATE)) {
1314                         free_one_page(zone, page, 0, migratetype);
1315                         goto out;
1316                 }
1317                 migratetype = MIGRATE_MOVABLE;
1318         }
1319 
1320         pcp = &this_cpu_ptr(zone->pageset)->pcp;
1321         if (cold)
1322                 list_add_tail(&page->lru, &pcp->lists[migratetype]);
1323         else
1324                 list_add(&page->lru, &pcp->lists[migratetype]);
1325         pcp->count++;
1326         if (pcp->count >= pcp->high) {
1327                 free_pcppages_bulk(zone, pcp->batch, pcp);
1328                 pcp->count -= pcp->batch;
1329         }
1330 
1331 out:
1332         local_irq_restore(flags);
1333 }
1334 
1335 /*
1336  * Free a list of 0-order pages
1337  */
1338 void free_hot_cold_page_list(struct list_head *list, int cold)
1339 {
1340         struct page *page, *next;
1341 
1342         list_for_each_entry_safe(page, next, list, lru) {
1343                 trace_mm_page_free_batched(page, cold);
1344                 free_hot_cold_page(page, cold);
1345         }
1346 }
1347 
1348 /*
1349  * split_page takes a non-compound higher-order page, and splits it into
1350  * n (1<<order) sub-pages: page[0..n]
1351  * Each sub-page must be freed individually.
1352  *
1353  * Note: this is probably too low level an operation for use in drivers.
1354  * Please consult with lkml before using this in your driver.
1355  */
1356 void split_page(struct page *page, unsigned int order)
1357 {
1358         int i;
1359 
1360         VM_BUG_ON(PageCompound(page));
1361         VM_BUG_ON(!page_count(page));
1362 
1363 #ifdef CONFIG_KMEMCHECK
1364         /*
1365          * Split shadow pages too, because free(page[0]) would
1366          * otherwise free the whole shadow.
1367          */
1368         if (kmemcheck_page_is_tracked(page))
1369                 split_page(virt_to_page(page[0].shadow), order);
1370 #endif
1371 
1372         for (i = 1; i < (1 << order); i++)
1373                 set_page_refcounted(page + i);
1374 }
1375 
1376 /*
1377  * Similar to split_page except the page is already free. As this is only
1378  * being used for migration, the migratetype of the block also changes.
1379  * As this is called with interrupts disabled, the caller is responsible
1380  * for calling arch_alloc_page() and kernel_map_page() after interrupts
1381  * are enabled.
1382  *
1383  * Note: this is probably too low level an operation for use in drivers.
1384  * Please consult with lkml before using this in your driver.
1385  */
1386 int split_free_page(struct page *page)
1387 {
1388         unsigned int order;
1389         unsigned long watermark;
1390         struct zone *zone;
1391 
1392         BUG_ON(!PageBuddy(page));
1393 
1394         zone = page_zone(page);
1395         order = page_order(page);
1396 
1397         /* Obey watermarks as if the page was being allocated */
1398         watermark = low_wmark_pages(zone) + (1 << order);
1399         if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
1400                 return 0;
1401 
1402         /* Remove page from free list */
1403         list_del(&page->lru);
1404         zone->free_area[order].nr_free--;
1405         rmv_page_order(page);
1406         __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
1407 
1408         /* Split into individual pages */
1409         set_page_refcounted(page);
1410         split_page(page, order);
1411 
1412         if (order >= pageblock_order - 1) {
1413                 struct page *endpage = page + (1 << order) - 1;
1414                 for (; page < endpage; page += pageblock_nr_pages) {
1415                         int mt = get_pageblock_migratetype(page);
1416                         if (mt != MIGRATE_ISOLATE && !is_migrate_cma(mt))
1417                                 set_pageblock_migratetype(page,
1418                                                           MIGRATE_MOVABLE);
1419                 }
1420         }
1421 
1422         return 1 << order;
1423 }
1424 
1425 /*
1426  * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
1427  * we cheat by calling it from here, in the order > 0 path.  Saves a branch
1428  * or two.
1429  */
1430 static inline
1431 struct page *buffered_rmqueue(struct zone *preferred_zone,
1432                         struct zone *zone, int order, gfp_t gfp_flags,
1433                         int migratetype)
1434 {
1435         unsigned long flags;
1436         struct page *page;
1437         int cold = !!(gfp_flags & __GFP_COLD);
1438 
1439 again:
1440         if (likely(order == 0)) {
1441                 struct per_cpu_pages *pcp;
1442                 struct list_head *list;
1443 
1444                 local_irq_save(flags);
1445                 pcp = &this_cpu_ptr(zone->pageset)->pcp;
1446                 list = &pcp->lists[migratetype];
1447                 if (list_empty(list)) {
1448                         pcp->count += rmqueue_bulk(zone, 0,
1449                                         pcp->batch, list,
1450                                         migratetype, cold);
1451                         if (unlikely(list_empty(list)))
1452                                 goto failed;
1453                 }
1454 
1455                 if (cold)
1456                         page = list_entry(list->prev, struct page, lru);
1457                 else
1458                         page = list_entry(list->next, struct page, lru);
1459 
1460                 list_del(&page->lru);
1461                 pcp->count--;
1462         } else {
1463                 if (unlikely(gfp_flags & __GFP_NOFAIL)) {
1464                         /*
1465                          * __GFP_NOFAIL is not to be used in new code.
1466                          *
1467                          * All __GFP_NOFAIL callers should be fixed so that they
1468                          * properly detect and handle allocation failures.
1469                          *
1470                          * We most definitely don't want callers attempting to
1471                          * allocate greater than order-1 page units with
1472                          * __GFP_NOFAIL.
1473                          */
1474                         WARN_ON_ONCE(order > 1);
1475                 }
1476                 spin_lock_irqsave(&zone->lock, flags);
1477                 page = __rmqueue(zone, order, migratetype);
1478                 spin_unlock(&zone->lock);
1479                 if (!page)
1480                         goto failed;
1481                 __mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << order));
1482         }
1483 
1484         __count_zone_vm_events(PGALLOC, zone, 1 << order);
1485         zone_statistics(preferred_zone, zone, gfp_flags);
1486         local_irq_restore(flags);
1487 
1488         VM_BUG_ON(bad_range(zone, page));
1489         if (prep_new_page(page, order, gfp_flags))
1490                 goto again;
1491         return page;
1492 
1493 failed:
1494         local_irq_restore(flags);
1495         return NULL;
1496 }
1497 
1498 /* The ALLOC_WMARK bits are used as an index to zone->watermark */
1499 #define ALLOC_WMARK_MIN         WMARK_MIN
1500 #define ALLOC_WMARK_LOW         WMARK_LOW
1501 #define ALLOC_WMARK_HIGH        WMARK_HIGH
1502 #define ALLOC_NO_WATERMARKS     0x04 /* don't check watermarks at all */
1503 
1504 /* Mask to get the watermark bits */
1505 #define ALLOC_WMARK_MASK        (ALLOC_NO_WATERMARKS-1)
1506 
1507 #define ALLOC_HARDER            0x10 /* try to alloc harder */
1508 #define ALLOC_HIGH              0x20 /* __GFP_HIGH set */
1509 #define ALLOC_CPUSET            0x40 /* check for correct cpuset */
1510 
1511 #ifdef CONFIG_FAIL_PAGE_ALLOC
1512 
1513 static struct {
1514         struct fault_attr attr;
1515 
1516         u32 ignore_gfp_highmem;
1517         u32 ignore_gfp_wait;
1518         u32 min_order;
1519 } fail_page_alloc = {
1520         .attr = FAULT_ATTR_INITIALIZER,
1521         .ignore_gfp_wait = 1,
1522         .ignore_gfp_highmem = 1,
1523         .min_order = 1,
1524 };
1525 
1526 static int __init setup_fail_page_alloc(char *str)
1527 {
1528         return setup_fault_attr(&fail_page_alloc.attr, str);
1529 }
1530 __setup("fail_page_alloc=", setup_fail_page_alloc);
1531 
1532 static int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
1533 {
1534         if (order < fail_page_alloc.min_order)
1535                 return 0;
1536         if (gfp_mask & __GFP_NOFAIL)
1537                 return 0;
1538         if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
1539                 return 0;
1540         if (fail_page_alloc.ignore_gfp_wait && (gfp_mask & __GFP_WAIT))
1541                 return 0;
1542 
1543         return should_fail(&fail_page_alloc.attr, 1 << order);
1544 }
1545 
1546 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
1547 
1548 static int __init fail_page_alloc_debugfs(void)
1549 {
1550         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
1551         struct dentry *dir;
1552 
1553         dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
1554                                         &fail_page_alloc.attr);
1555         if (IS_ERR(dir))
1556                 return PTR_ERR(dir);
1557 
1558         if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
1559                                 &fail_page_alloc.ignore_gfp_wait))
1560                 goto fail;
1561         if (!debugfs_create_bool("ignore-gfp-highmem", mode, dir,
1562                                 &fail_page_alloc.ignore_gfp_highmem))
1563                 goto fail;
1564         if (!debugfs_create_u32("min-order", mode, dir,
1565                                 &fail_page_alloc.min_order))
1566                 goto fail;
1567 
1568         return 0;
1569 fail:
1570         debugfs_remove_recursive(dir);
1571 
1572         return -ENOMEM;
1573 }
1574 
1575 late_initcall(fail_page_alloc_debugfs);
1576 
1577 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
1578 
1579 #else /* CONFIG_FAIL_PAGE_ALLOC */
1580 
1581 static inline int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
1582 {
1583         return 0;
1584 }
1585 
1586 #endif /* CONFIG_FAIL_PAGE_ALLOC */
1587 
1588 /*
1589  * Return true if free pages are above 'mark'. This takes into account the order
1590  * of the allocation.
1591  */
1592 static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
1593                       int classzone_idx, int alloc_flags, long free_pages)
1594 {
1595         /* free_pages my go negative - that's OK */
1596         long min = mark;
1597         int o;
1598 
1599         free_pages -= (1 << order) - 1;
1600         if (alloc_flags & ALLOC_HIGH)
1601                 min -= min / 2;
1602         if (alloc_flags & ALLOC_HARDER)
1603                 min -= min / 4;
1604 
1605         if (free_pages <= min + z->lowmem_reserve[classzone_idx])
1606                 return false;
1607         for (o = 0; o < order; o++) {
1608                 /* At the next order, this order's pages become unavailable */
1609                 free_pages -= z->free_area[o].nr_free << o;
1610 
1611                 /* Require fewer higher order pages to be free */
1612                 min >>= 1;
1613 
1614                 if (free_pages <= min)
1615                         return false;
1616         }
1617         return true;
1618 }
1619 
1620 bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
1621                       int classzone_idx, int alloc_flags)
1622 {
1623         return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
1624                                         zone_page_state(z, NR_FREE_PAGES));
1625 }
1626 
1627 bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
1628                       int classzone_idx, int alloc_flags)
1629 {
1630         long free_pages = zone_page_state(z, NR_FREE_PAGES);
1631 
1632         if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
1633                 free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
1634 
1635         return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
1636                                                                 free_pages);
1637 }
1638 
1639 #ifdef CONFIG_NUMA
1640 /*
1641  * zlc_setup - Setup for "zonelist cache".  Uses cached zone data to
1642  * skip over zones that are not allowed by the cpuset, or that have
1643  * been recently (in last second) found to be nearly full.  See further
1644  * comments in mmzone.h.  Reduces cache footprint of zonelist scans
1645  * that have to skip over a lot of full or unallowed zones.
1646  *
1647  * If the zonelist cache is present in the passed in zonelist, then
1648  * returns a pointer to the allowed node mask (either the current
1649  * tasks mems_allowed, or node_states[N_HIGH_MEMORY].)
1650  *
1651  * If the zonelist cache is not available for this zonelist, does
1652  * nothing and returns NULL.
1653  *
1654  * If the fullzones BITMAP in the zonelist cache is stale (more than
1655  * a second since last zap'd) then we zap it out (clear its bits.)
1656  *
1657  * We hold off even calling zlc_setup, until after we've checked the
1658  * first zone in the zonelist, on the theory that most allocations will
1659  * be satisfied from that first zone, so best to examine that zone as
1660  * quickly as we can.
1661  */
1662 static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
1663 {
1664         struct zonelist_cache *zlc;     /* cached zonelist speedup info */
1665         nodemask_t *allowednodes;       /* zonelist_cache approximation */
1666 
1667         zlc = zonelist->zlcache_ptr;
1668         if (!zlc)
1669                 return NULL;
1670 
1671         if (time_after(jiffies, zlc->last_full_zap + HZ)) {
1672                 bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
1673                 zlc->last_full_zap = jiffies;
1674         }
1675 
1676         allowednodes = !in_interrupt() && (alloc_flags & ALLOC_CPUSET) ?
1677                                         &cpuset_current_mems_allowed :
1678                                         &node_states[N_HIGH_MEMORY];
1679         return allowednodes;
1680 }
1681 
1682 /*
1683  * Given 'z' scanning a zonelist, run a couple of quick checks to see
1684  * if it is worth looking at further for free memory:
1685  *  1) Check that the zone isn't thought to be full (doesn't have its
1686  *     bit set in the zonelist_cache fullzones BITMAP).
1687  *  2) Check that the zones node (obtained from the zonelist_cache
1688  *     z_to_n[] mapping) is allowed in the passed in allowednodes mask.
1689  * Return true (non-zero) if zone is worth looking at further, or
1690  * else return false (zero) if it is not.
1691  *
1692  * This check -ignores- the distinction between various watermarks,
1693  * such as GFP_HIGH, GFP_ATOMIC, PF_MEMALLOC, ...  If a zone is
1694  * found to be full for any variation of these watermarks, it will
1695  * be considered full for up to one second by all requests, unless
1696  * we are so low on memory on all allowed nodes that we are forced
1697  * into the second scan of the zonelist.
1698  *
1699  * In the second scan we ignore this zonelist cache and exactly
1700  * apply the watermarks to all zones, even it is slower to do so.
1701  * We are low on memory in the second scan, and should leave no stone
1702  * unturned looking for a free page.
1703  */
1704 static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zoneref *z,
1705                                                 nodemask_t *allowednodes)
1706 {
1707         struct zonelist_cache *zlc;     /* cached zonelist speedup info */
1708         int i;                          /* index of *z in zonelist zones */
1709         int n;                          /* node that zone *z is on */
1710 
1711         zlc = zonelist->zlcache_ptr;
1712         if (!zlc)
1713                 return 1;
1714 
1715         i = z - zonelist->_zonerefs;
1716         n = zlc->z_to_n[i];
1717 
1718         /* This zone is worth trying if it is allowed but not full */
1719         return node_isset(n, *allowednodes) && !test_bit(i, zlc->fullzones);
1720 }
1721 
1722 /*
1723  * Given 'z' scanning a zonelist, set the corresponding bit in
1724  * zlc->fullzones, so that subsequent attempts to allocate a page
1725  * from that zone don't waste time re-examining it.
1726  */
1727 static void zlc_mark_zone_full(struct zonelist *zonelist, struct zoneref *z)
1728 {
1729         struct zonelist_cache *zlc;     /* cached zonelist speedup info */
1730         int i;                          /* index of *z in zonelist zones */
1731 
1732         zlc = zonelist->zlcache_ptr;
1733         if (!zlc)
1734                 return;
1735 
1736         i = z - zonelist->_zonerefs;
1737 
1738         set_bit(i, zlc->fullzones);
1739 }
1740 
1741 /*
1742  * clear all zones full, called after direct reclaim makes progress so that
1743  * a zone that was recently full is not skipped over for up to a second
1744  */
1745 static void zlc_clear_zones_full(struct zonelist *zonelist)
1746 {
1747         struct zonelist_cache *zlc;     /* cached zonelist speedup info */
1748 
1749         zlc = zonelist->zlcache_ptr;
1750         if (!zlc)
1751                 return;
1752 
1753         bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
1754 }
1755 
1756 #else   /* CONFIG_NUMA */
1757 
1758 static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
1759 {
1760         return NULL;
1761 }
1762 
1763 static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zoneref *z,
1764                                 nodemask_t *allowednodes)
1765 {
1766         return 1;
1767 }
1768 
1769 static void zlc_mark_zone_full(struct zonelist *zonelist, struct zoneref *z)
1770 {
1771 }
1772 
1773 static void zlc_clear_zones_full(struct zonelist *zonelist)
1774 {
1775 }
1776 #endif  /* CONFIG_NUMA */
1777 
1778 /*
1779  * get_page_from_freelist goes through the zonelist trying to allocate
1780  * a page.
1781  */
1782 static struct page *
1783 get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
1784                 struct zonelist *zonelist, int high_zoneidx, int alloc_flags,
1785                 struct zone *preferred_zone, int migratetype)
1786 {
1787         struct zoneref *z;
1788         struct page *page = NULL;
1789         int classzone_idx;
1790         struct zone *zone;
1791         nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
1792         int zlc_active = 0;             /* set if using zonelist_cache */
1793         int did_zlc_setup = 0;          /* just call zlc_setup() one time */
1794 
1795         classzone_idx = zone_idx(preferred_zone);
1796 zonelist_scan:
1797         /*
1798          * Scan zonelist, looking for a zone with enough free.
1799          * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
1800          */
1801         for_each_zone_zonelist_nodemask(zone, z, zonelist,
1802                                                 high_zoneidx, nodemask) {
1803                 if (NUMA_BUILD && zlc_active &&
1804                         !zlc_zone_worth_trying(zonelist, z, allowednodes))
1805                                 continue;
1806                 if ((alloc_flags & ALLOC_CPUSET) &&
1807                         !cpuset_zone_allowed_softwall(zone, gfp_mask))
1808                                 continue;
1809                 /*
1810                  * When allocating a page cache page for writing, we
1811                  * want to get it from a zone that is within its dirty
1812                  * limit, such that no single zone holds more than its
1813                  * proportional share of globally allowed dirty pages.
1814                  * The dirty limits take into account the zone's
1815                  * lowmem reserves and high watermark so that kswapd
1816                  * should be able to balance it without having to
1817                  * write pages from its LRU list.
1818                  *
1819                  * This may look like it could increase pressure on
1820                  * lower zones by failing allocations in higher zones
1821                  * before they are full.  But the pages that do spill
1822                  * over are limited as the lower zones are protected
1823                  * by this very same mechanism.  It should not become
1824                  * a practical burden to them.
1825                  *
1826                  * XXX: For now, allow allocations to potentially
1827                  * exceed the per-zone dirty limit in the slowpath
1828                  * (ALLOC_WMARK_LOW unset) before going into reclaim,
1829                  * which is important when on a NUMA setup the allowed
1830                  * zones are together not big enough to reach the
1831                  * global limit.  The proper fix for these situations
1832                  * will require awareness of zones in the
1833                  * dirty-throttling and the flusher threads.
1834                  */
1835                 if ((alloc_flags & ALLOC_WMARK_LOW) &&
1836                     (gfp_mask & __GFP_WRITE) && !zone_dirty_ok(zone))
1837                         goto this_zone_full;
1838 
1839                 BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
1840                 if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
1841                         unsigned long mark;
1842                         int ret;
1843 
1844                         mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
1845                         if (zone_watermark_ok(zone, order, mark,
1846                                     classzone_idx, alloc_flags))
1847                                 goto try_this_zone;
1848 
1849                         if (NUMA_BUILD && !did_zlc_setup && nr_online_nodes > 1) {
1850                                 /*
1851                                  * we do zlc_setup if there are multiple nodes
1852                                  * and before considering the first zone allowed
1853                                  * by the cpuset.
1854                                  */
1855                                 allowednodes = zlc_setup(zonelist, alloc_flags);
1856                                 zlc_active = 1;
1857                                 did_zlc_setup = 1;
1858                         }
1859 
1860                         if (zone_reclaim_mode == 0)
1861                                 goto this_zone_full;
1862 
1863                         /*
1864                          * As we may have just activated ZLC, check if the first
1865                          * eligible zone has failed zone_reclaim recently.
1866                          */
1867                         if (NUMA_BUILD && zlc_active &&
1868                                 !zlc_zone_worth_trying(zonelist, z, allowednodes))
1869                                 continue;
1870 
1871                         ret = zone_reclaim(zone, gfp_mask, order);
1872                         switch (ret) {
1873                         case ZONE_RECLAIM_NOSCAN:
1874                                 /* did not scan */
1875                                 continue;
1876                         case ZONE_RECLAIM_FULL:
1877                                 /* scanned but unreclaimable */
1878                                 continue;
1879                         default:
1880                                 /* did we reclaim enough */
1881                                 if (!zone_watermark_ok(zone, order, mark,
1882                                                 classzone_idx, alloc_flags))
1883                                         goto this_zone_full;
1884                         }
1885                 }
1886 
1887 try_this_zone:
1888                 page = buffered_rmqueue(preferred_zone, zone, order,
1889                                                 gfp_mask, migratetype);
1890                 if (page)
1891                         break;
1892 this_zone_full:
1893                 if (NUMA_BUILD)
1894                         zlc_mark_zone_full(zonelist, z);
1895         }
1896 
1897         if (unlikely(NUMA_BUILD && page == NULL && zlc_active)) {
1898                 /* Disable zlc cache for second zonelist scan */
1899                 zlc_active = 0;
1900                 goto zonelist_scan;
1901         }
1902         return page;
1903 }
1904 
1905 /*
1906  * Large machines with many possible nodes should not always dump per-node
1907  * meminfo in irq context.
1908  */
1909 static inline bool should_suppress_show_mem(void)
1910 {
1911         bool ret = false;
1912 
1913 #if NODES_SHIFT > 8
1914         ret = in_interrupt();
1915 #endif
1916         return ret;
1917 }
1918 
1919 static DEFINE_RATELIMIT_STATE(nopage_rs,
1920                 DEFAULT_RATELIMIT_INTERVAL,
1921                 DEFAULT_RATELIMIT_BURST);
1922 
1923 void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...)
1924 {
1925         unsigned int filter = SHOW_MEM_FILTER_NODES;
1926 
1927         if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) ||
1928             debug_guardpage_minorder() > 0)
1929                 return;
1930 
1931         /*
1932          * This documents exceptions given to allocations in certain
1933          * contexts that are allowed to allocate outside current's set
1934          * of allowed nodes.
1935          */
1936         if (!(gfp_mask & __GFP_NOMEMALLOC))
1937                 if (test_thread_flag(TIF_MEMDIE) ||
1938                     (current->flags & (PF_MEMALLOC | PF_EXITING)))
1939                         filter &= ~SHOW_MEM_FILTER_NODES;
1940         if (in_interrupt() || !(gfp_mask & __GFP_WAIT))
1941                 filter &= ~SHOW_MEM_FILTER_NODES;
1942 
1943         if (fmt) {
1944                 struct va_format vaf;
1945                 va_list args;
1946 
1947                 va_start(args, fmt);
1948 
1949                 vaf.fmt = fmt;
1950                 vaf.va = &args;
1951 
1952                 pr_warn("%pV", &vaf);
1953 
1954                 va_end(args);
1955         }
1956 
1957         pr_warn("%s: page allocation failure: order:%d, mode:0x%x\n",
1958                 current->comm, order, gfp_mask);
1959 
1960         dump_stack();
1961         if (!should_suppress_show_mem())
1962                 show_mem(filter);
1963 }
1964 
1965 static inline int
1966 should_alloc_retry(gfp_t gfp_mask, unsigned int order,
1967                                 unsigned long did_some_progress,
1968                                 unsigned long pages_reclaimed)
1969 {
1970         /* Do not loop if specifically requested */
1971         if (gfp_mask & __GFP_NORETRY)
1972                 return 0;
1973 
1974         /* Always retry if specifically requested */
1975         if (gfp_mask & __GFP_NOFAIL)
1976                 return 1;
1977 
1978         /*
1979          * Suspend converts GFP_KERNEL to __GFP_WAIT which can prevent reclaim
1980          * making forward progress without invoking OOM. Suspend also disables
1981          * storage devices so kswapd will not help. Bail if we are suspending.
1982          */
1983         if (!did_some_progress && pm_suspended_storage())
1984                 return 0;
1985 
1986         /*
1987          * In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
1988          * means __GFP_NOFAIL, but that may not be true in other
1989          * implementations.
1990          */
1991         if (order <= PAGE_ALLOC_COSTLY_ORDER)
1992                 return 1;
1993 
1994         /*
1995          * For order > PAGE_ALLOC_COSTLY_ORDER, if __GFP_REPEAT is
1996          * specified, then we retry until we no longer reclaim any pages
1997          * (above), or we've reclaimed an order of pages at least as
1998          * large as the allocation's order. In both cases, if the
1999          * allocation still fails, we stop retrying.
2000          */
2001         if (gfp_mask & __GFP_REPEAT && pages_reclaimed < (1 << order))
2002                 return 1;
2003 
2004         return 0;
2005 }
2006 
2007 static inline struct page *
2008 __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
2009         struct zonelist *zonelist, enum zone_type high_zoneidx,
2010         nodemask_t *nodemask, struct zone *preferred_zone,
2011         int migratetype)
2012 {
2013         struct page *page;
2014 
2015         /* Acquire the OOM killer lock for the zones in zonelist */
2016         if (!try_set_zonelist_oom(zonelist, gfp_mask)) {
2017                 schedule_timeout_uninterruptible(1);
2018                 return NULL;
2019         }
2020 
2021         /*
2022          * Go through the zonelist yet one more time, keep very high watermark
2023          * here, this is only to catch a parallel oom killing, we must fail if
2024          * we're still under heavy pressure.
2025          */
2026         page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask,
2027                 order, zonelist, high_zoneidx,
2028                 ALLOC_WMARK_HIGH|ALLOC_CPUSET,
2029                 preferred_zone, migratetype);
2030         if (page)
2031                 goto out;
2032 
2033         if (!(gfp_mask & __GFP_NOFAIL)) {
2034                 /* The OOM killer will not help higher order allocs */
2035                 if (order > PAGE_ALLOC_COSTLY_ORDER)
2036                         goto out;
2037                 /* The OOM killer does not needlessly kill tasks for lowmem */
2038                 if (high_zoneidx < ZONE_NORMAL)
2039                         goto out;
2040                 /*
2041                  * GFP_THISNODE contains __GFP_NORETRY and we never hit this.
2042                  * Sanity check for bare calls of __GFP_THISNODE, not real OOM.
2043                  * The caller should handle page allocation failure by itself if
2044                  * it specifies __GFP_THISNODE.
2045                  * Note: Hugepage uses it but will hit PAGE_ALLOC_COSTLY_ORDER.
2046                  */
2047                 if (gfp_mask & __GFP_THISNODE)
2048                         goto out;
2049         }
2050         /* Exhausted what can be done so it's blamo time */
2051         out_of_memory(zonelist, gfp_mask, order, nodemask, false);
2052 
2053 out:
2054         clear_zonelist_oom(zonelist, gfp_mask);
2055         return page;
2056 }
2057 
2058 #ifdef CONFIG_COMPACTION
2059 /* Try memory compaction for high-order allocations before reclaim */
2060 static struct page *
2061 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
2062         struct zonelist *zonelist, enum zone_type high_zoneidx,
2063         nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
2064         int migratetype, bool sync_migration,
2065         bool *deferred_compaction,
2066         unsigned long *did_some_progress)
2067 {
2068         struct page *page;
2069 
2070         if (!order)
2071                 return NULL;
2072 
2073         if (compaction_deferred(preferred_zone, order)) {
2074                 *deferred_compaction = true;
2075                 return NULL;
2076         }
2077 
2078         current->flags |= PF_MEMALLOC;
2079         *did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask,
2080                                                 nodemask, sync_migration);
2081         current->flags &= ~PF_MEMALLOC;
2082         if (*did_some_progress != COMPACT_SKIPPED) {
2083 
2084                 /* Page migration frees to the PCP lists but we want merging */
2085                 drain_pages(get_cpu());
2086                 put_cpu();
2087 
2088                 page = get_page_from_freelist(gfp_mask, nodemask,
2089                                 order, zonelist, high_zoneidx,
2090                                 alloc_flags, preferred_zone,
2091                                 migratetype);
2092                 if (page) {
2093                         preferred_zone->compact_considered = 0;
2094                         preferred_zone->compact_defer_shift = 0;
2095                         if (order >= preferred_zone->compact_order_failed)
2096                                 preferred_zone->compact_order_failed = order + 1;
2097                         count_vm_event(COMPACTSUCCESS);
2098                         return page;
2099                 }
2100 
2101                 /*
2102                  * It's bad if compaction run occurs and fails.
2103                  * The most likely reason is that pages exist,
2104                  * but not enough to satisfy watermarks.
2105                  */
2106                 count_vm_event(COMPACTFAIL);
2107 
2108                 /*
2109                  * As async compaction considers a subset of pageblocks, only
2110                  * defer if the failure was a sync compaction failure.
2111                  */
2112                 if (sync_migration)
2113                         defer_compaction(preferred_zone, order);
2114 
2115                 cond_resched();
2116         }
2117 
2118         return NULL;
2119 }
2120 #else
2121 static inline struct page *
2122 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
2123         struct zonelist *zonelist, enum zone_type high_zoneidx,
2124         nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
2125         int migratetype, bool sync_migration,
2126         bool *deferred_compaction,
2127         unsigned long *did_some_progress)
2128 {
2129         return NULL;
2130 }
2131 #endif /* CONFIG_COMPACTION */
2132 
2133 /* Perform direct synchronous page reclaim */
2134 static int
2135 __perform_reclaim(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist,
2136                   nodemask_t *nodemask)
2137 {
2138         struct reclaim_state reclaim_state;
2139         int progress;
2140 
2141         cond_resched();
2142 
2143         /* We now go into synchronous reclaim */
2144         cpuset_memory_pressure_bump();
2145         current->flags |= PF_MEMALLOC;
2146         lockdep_set_current_reclaim_state(gfp_mask);
2147         reclaim_state.reclaimed_slab = 0;
2148         current->reclaim_state = &reclaim_state;
2149 
2150         progress = try_to_free_pages(zonelist, order, gfp_mask, nodemask);
2151 
2152         current->reclaim_state = NULL;
2153         lockdep_clear_current_reclaim_state();
2154         current->flags &= ~PF_MEMALLOC;
2155 
2156         cond_resched();
2157 
2158         return progress;
2159 }
2160 
2161 /* The really slow allocator path where we enter direct reclaim */
2162 static inline struct page *
2163 __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
2164         struct zonelist *zonelist, enum zone_type high_zoneidx,
2165         nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
2166         int migratetype, unsigned long *did_some_progress)
2167 {
2168         struct page *page = NULL;
2169         bool drained = false;
2170 
2171         *did_some_progress = __perform_reclaim(gfp_mask, order, zonelist,
2172                                                nodemask);
2173         if (unlikely(!(*did_some_progress)))
2174                 return NULL;
2175 
2176         /* After successful reclaim, reconsider all zones for allocation */
2177         if (NUMA_BUILD)
2178                 zlc_clear_zones_full(zonelist);
2179 
2180 retry:
2181         page = get_page_from_freelist(gfp_mask, nodemask, order,
2182                                         zonelist, high_zoneidx,
2183                                         alloc_flags, preferred_zone,
2184                                         migratetype);
2185 
2186         /*
2187          * If an allocation failed after direct reclaim, it could be because
2188          * pages are pinned on the per-cpu lists. Drain them and try again
2189          */
2190         if (!page && !drained) {
2191                 drain_all_pages();
2192                 drained = true;
2193                 goto retry;
2194         }
2195 
2196         return page;
2197 }
2198 
2199 /*
2200  * This is called in the allocator slow-path if the allocation request is of
2201  * sufficient urgency to ignore watermarks and take other desperate measures
2202  */
2203 static inline struct page *
2204 __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
2205         struct zonelist *zonelist, enum zone_type high_zoneidx,
2206         nodemask_t *nodemask, struct zone *preferred_zone,
2207         int migratetype)
2208 {
2209         struct page *page;
2210 
2211         do {
2212                 page = get_page_from_freelist(gfp_mask, nodemask, order,
2213                         zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,
2214                         preferred_zone, migratetype);
2215 
2216                 if (!page && gfp_mask & __GFP_NOFAIL)
2217                         wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
2218         } while (!page && (gfp_mask & __GFP_NOFAIL));
2219 
2220         return page;
2221 }
2222 
2223 static inline
2224 void wake_all_kswapd(unsigned int order, struct zonelist *zonelist,
2225                                                 enum zone_type high_zoneidx,
2226                                                 enum zone_type classzone_idx)
2227 {
2228         struct zoneref *z;
2229         struct zone *zone;
2230 
2231         for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
2232                 wakeup_kswapd(zone, order, classzone_idx);
2233 }
2234 
2235 static inline int
2236 gfp_to_alloc_flags(gfp_t gfp_mask)
2237 {
2238         int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
2239         const gfp_t wait = gfp_mask & __GFP_WAIT;
2240 
2241         /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
2242         BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
2243 
2244         /*
2245          * The caller may dip into page reserves a bit more if the caller
2246          * cannot run direct reclaim, or if the caller has realtime scheduling
2247          * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
2248          * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
2249          */
2250         alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
2251 
2252         if (!wait) {
2253                 /*
2254                  * Not worth trying to allocate harder for
2255                  * __GFP_NOMEMALLOC even if it can't schedule.
2256                  */
2257                 if  (!(gfp_mask & __GFP_NOMEMALLOC))
2258                         alloc_flags |= ALLOC_HARDER;
2259                 /*
2260                  * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
2261                  * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
2262                  */
2263                 alloc_flags &= ~ALLOC_CPUSET;
2264         } else if (unlikely(rt_task(current)) && !in_interrupt())
2265                 alloc_flags |= ALLOC_HARDER;
2266 
2267         if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {
2268                 if (!in_interrupt() &&
2269                     ((current->flags & PF_MEMALLOC) ||
2270                      unlikely(test_thread_flag(TIF_MEMDIE))))
2271                         alloc_flags |= ALLOC_NO_WATERMARKS;
2272         }
2273 
2274         return alloc_flags;
2275 }
2276 
2277 static inline struct page *
2278 __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
2279         struct zonelist *zonelist, enum zone_type high_zoneidx,
2280         nodemask_t *nodemask, struct zone *preferred_zone,
2281         int migratetype)
2282 {
2283         const gfp_t wait = gfp_mask & __GFP_WAIT;
2284         struct page *page = NULL;
2285         int alloc_flags;
2286         unsigned long pages_reclaimed = 0;
2287         unsigned long did_some_progress;
2288         bool sync_migration = false;
2289         bool deferred_compaction = false;
2290 
2291         /*
2292          * In the slowpath, we sanity check order to avoid ever trying to
2293          * reclaim >= MAX_ORDER areas which will never succeed. Callers may
2294          * be using allocators in order of preference for an area that is
2295          * too large.
2296          */
2297         if (order >= MAX_ORDER) {
2298                 WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
2299                 return NULL;
2300         }
2301 
2302         /*
2303          * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and
2304          * __GFP_NOWARN set) should not cause reclaim since the subsystem
2305          * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim
2306          * using a larger set of nodes after it has established that the
2307          * allowed per node queues are empty and that nodes are
2308          * over allocated.
2309          */
2310         if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
2311                 goto nopage;
2312 
2313 restart:
2314         if (!(gfp_mask & __GFP_NO_KSWAPD))
2315                 wake_all_kswapd(order, zonelist, high_zoneidx,
2316                                                 zone_idx(preferred_zone));
2317 
2318         /*
2319          * OK, we're below the kswapd watermark and have kicked background
2320          * reclaim. Now things get more complex, so set up alloc_flags according
2321          * to how we want to proceed.
2322          */
2323         alloc_flags = gfp_to_alloc_flags(gfp_mask);
2324 
2325         /*
2326          * Find the true preferred zone if the allocation is unconstrained by
2327          * cpusets.
2328          */
2329         if (!(alloc_flags & ALLOC_CPUSET) && !nodemask)
2330                 first_zones_zonelist(zonelist, high_zoneidx, NULL,
2331                                         &preferred_zone);
2332 
2333 rebalance:
2334         /* This is the last chance, in general, before the goto nopage. */
2335         page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist,
2336                         high_zoneidx, alloc_flags & ~ALLOC_NO_WATERMARKS,
2337                         preferred_zone, migratetype);
2338         if (page)
2339                 goto got_pg;
2340 
2341         /* Allocate without watermarks if the context allows */
2342         if (alloc_flags & ALLOC_NO_WATERMARKS) {
2343                 page = __alloc_pages_high_priority(gfp_mask, order,
2344                                 zonelist, high_zoneidx, nodemask,
2345                                 preferred_zone, migratetype);
2346                 if (page)
2347                         goto got_pg;
2348         }
2349 
2350         /* Atomic allocations - we can't balance anything */
2351         if (!wait)
2352                 goto nopage;
2353 
2354         /* Avoid recursion of direct reclaim */
2355         if (current->flags & PF_MEMALLOC)
2356                 goto nopage;
2357 
2358         /* Avoid allocations with no watermarks from looping endlessly */
2359         if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
2360                 goto nopage;
2361 
2362         /*
2363          * Try direct compaction. The first pass is asynchronous. Subsequent
2364          * attempts after direct reclaim are synchronous
2365          */
2366         page = __alloc_pages_direct_compact(gfp_mask, order,
2367                                         zonelist, high_zoneidx,
2368                                         nodemask,
2369                                         alloc_flags, preferred_zone,
2370                                         migratetype, sync_migration,
2371                                         &deferred_compaction,
2372                                         &did_some_progress);
2373         if (page)
2374                 goto got_pg;
2375         sync_migration = true;
2376 
2377         /*
2378          * If compaction is deferred for high-order allocations, it is because
2379          * sync compaction recently failed. In this is the case and the caller
2380          * has requested the system not be heavily disrupted, fail the
2381          * allocation now instead of entering direct reclaim
2382          */
2383         if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD))
2384                 goto nopage;
2385 
2386         /* Try direct reclaim and then allocating */
2387         page = __alloc_pages_direct_reclaim(gfp_mask, order,
2388                                         zonelist, high_zoneidx,
2389                                         nodemask,
2390                                         alloc_flags, preferred_zone,
2391                                         migratetype, &did_some_progress);
2392         if (page)
2393                 goto got_pg;
2394 
2395         /*
2396          * If we failed to make any progress reclaiming, then we are
2397          * running out of options and have to consider going OOM
2398          */
2399         if (!did_some_progress) {
2400                 if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
2401                         if (oom_killer_disabled)
2402                                 goto nopage;
2403                         /* Coredumps can quickly deplete all memory reserves */
2404                         if ((current->flags & PF_DUMPCORE) &&
2405                             !(gfp_mask & __GFP_NOFAIL))
2406                                 goto nopage;
2407                         page = __alloc_pages_may_oom(gfp_mask, order,
2408                                         zonelist, high_zoneidx,
2409                                         nodemask, preferred_zone,
2410                                         migratetype);
2411                         if (page)
2412                                 goto got_pg;
2413 
2414                         if (!(gfp_mask & __GFP_NOFAIL)) {
2415                                 /*
2416                                  * The oom killer is not called for high-order
2417                                  * allocations that may fail, so if no progress
2418                                  * is being made, there are no other options and
2419                                  * retrying is unlikely to help.
2420                                  */
2421                                 if (order > PAGE_ALLOC_COSTLY_ORDER)
2422                                         goto nopage;
2423                                 /*
2424                                  * The oom killer is not called for lowmem
2425                                  * allocations to prevent needlessly killing
2426                                  * innocent tasks.
2427                                  */
2428                                 if (high_zoneidx < ZONE_NORMAL)
2429                                         goto nopage;
2430                         }
2431 
2432                         goto restart;
2433                 }
2434         }
2435 
2436         /* Check if we should retry the allocation */
2437         pages_reclaimed += did_some_progress;
2438         if (should_alloc_retry(gfp_mask, order, did_some_progress,
2439                                                 pages_reclaimed)) {
2440                 /* Wait for some write requests to complete then retry */
2441                 wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
2442                 goto rebalance;
2443         } else {
2444                 /*
2445                  * High-order allocations do not necessarily loop after
2446                  * direct reclaim and reclaim/compaction depends on compaction
2447                  * being called after reclaim so call directly if necessary
2448                  */
2449                 page = __alloc_pages_direct_compact(gfp_mask, order,
2450                                         zonelist, high_zoneidx,
2451                                         nodemask,
2452                                         alloc_flags, preferred_zone,
2453                                         migratetype, sync_migration,
2454                                         &deferred_compaction,
2455                                         &did_some_progress);
2456                 if (page)
2457                         goto got_pg;
2458         }
2459 
2460 nopage:
2461         warn_alloc_failed(gfp_mask, order, NULL);
2462         return page;
2463 got_pg:
2464         if (kmemcheck_enabled)
2465                 kmemcheck_pagealloc_alloc(page, order, gfp_mask);
2466         return page;
2467 
2468 }
2469 
2470 /*
2471  * This is the 'heart' of the zoned buddy allocator.
2472  */
2473 struct page *
2474 __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
2475                         struct zonelist *zonelist, nodemask_t *nodemask)
2476 {
2477         enum zone_type high_zoneidx = gfp_zone(gfp_mask);
2478         struct zone *preferred_zone;
2479         struct page *page = NULL;
2480         int migratetype = allocflags_to_migratetype(gfp_mask);
2481         unsigned int cpuset_mems_cookie;
2482 
2483         gfp_mask &= gfp_allowed_mask;
2484 
2485         lockdep_trace_alloc(gfp_mask);
2486 
2487         might_sleep_if(gfp_mask & __GFP_WAIT);
2488 
2489         if (should_fail_alloc_page(gfp_mask, order))
2490                 return NULL;
2491 
2492         /*
2493          * Check the zones suitable for the gfp_mask contain at least one
2494          * valid zone. It's possible to have an empty zonelist as a result
2495          * of GFP_THISNODE and a memoryless node
2496          */
2497         if (unlikely(!zonelist->_zonerefs->zone))
2498                 return NULL;
2499 
2500 retry_cpuset:
2501         cpuset_mems_cookie = get_mems_allowed();
2502 
2503         /* The preferred zone is used for statistics later */
2504         first_zones_zonelist(zonelist, high_zoneidx,
2505                                 nodemask ? : &cpuset_current_mems_allowed,
2506                                 &preferred_zone);
2507         if (!preferred_zone)
2508                 goto out;
2509 
2510         /* First allocation attempt */
2511         page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
2512                         zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,
2513                         preferred_zone, migratetype);
2514         if (unlikely(!page))
2515                 page = __alloc_pages_slowpath(gfp_mask, order,
2516                                 zonelist, high_zoneidx, nodemask,
2517                                 preferred_zone, migratetype);
2518 
2519         trace_mm_page_alloc(page, order, gfp_mask, migratetype);
2520 
2521 out:
2522         /*
2523          * When updating a task's mems_allowed, it is possible to race with
2524          * parallel threads in such a way that an allocation can fail while
2525          * the mask is being updated. If a page allocation is about to fail,
2526          * check if the cpuset changed during allocation and if so, retry.
2527          */
2528         if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
2529                 goto retry_cpuset;
2530 
2531         return page;
2532 }
2533 EXPORT_SYMBOL(__alloc_pages_nodemask);
2534 
2535 /*
2536  * Common helper functions.
2537  */
2538 unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
2539 {
2540         struct page *page;
2541 
2542         /*
2543          * __get_free_pages() returns a 32-bit address, which cannot represent
2544          * a highmem page
2545          */
2546         VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
2547 
2548         page = alloc_pages(gfp_mask, order);
2549         if (!page)
2550                 return 0;
2551         return (unsigned long) page_address(page);
2552 }
2553 EXPORT_SYMBOL(__get_free_pages);
2554 
2555 unsigned long get_zeroed_page(gfp_t gfp_mask)
2556 {
2557         return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
2558 }
2559 EXPORT_SYMBOL(get_zeroed_page);
2560 
2561 void __free_pages(struct page *page, unsigned int order)
2562 {
2563         if (put_page_testzero(page)) {
2564                 if (order == 0)
2565                         free_hot_cold_page(page, 0);
2566                 else
2567                         __free_pages_ok(page, order);
2568         }
2569 }
2570 
2571 EXPORT_SYMBOL(__free_pages);
2572 
2573 void free_pages(unsigned long addr, unsigned int order)
2574 {
2575         if (addr != 0) {
2576                 VM_BUG_ON(!virt_addr_valid((void *)addr));
2577                 __free_pages(virt_to_page((void *)addr), order);
2578         }
2579 }
2580 
2581 EXPORT_SYMBOL(free_pages);
2582 
2583 static void *make_alloc_exact(unsigned long addr, unsigned order, size_t size)
2584 {
2585         if (addr) {
2586                 unsigned long alloc_end = addr + (PAGE_SIZE << order);
2587                 unsigned long used = addr + PAGE_ALIGN(size);
2588 
2589                 split_page(virt_to_page((void *)addr), order);
2590                 while (used < alloc_end) {
2591                         free_page(used);
2592                         used += PAGE_SIZE;
2593                 }
2594         }
2595         return (void *)addr;
2596 }
2597 
2598 /**
2599  * alloc_pages_exact - allocate an exact number physically-contiguous pages.
2600  * @size: the number of bytes to allocate
2601  * @gfp_mask: GFP flags for the allocation
2602  *
2603  * This function is similar to alloc_pages(), except that it allocates the
2604  * minimum number of pages to satisfy the request.  alloc_pages() can only
2605  * allocate memory in power-of-two pages.
2606  *
2607  * This function is also limited by MAX_ORDER.
2608  *
2609  * Memory allocated by this function must be released by free_pages_exact().
2610  */
2611 void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
2612 {
2613         unsigned int order = get_order(size);
2614         unsigned long addr;
2615 
2616         addr = __get_free_pages(gfp_mask, order);
2617         return make_alloc_exact(addr, order, size);
2618 }
2619 EXPORT_SYMBOL(alloc_pages_exact);
2620 
2621 /**
2622  * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
2623  *                         pages on a node.
2624  * @nid: the preferred node ID where memory should be allocated
2625  * @size: the number of bytes to allocate
2626  * @gfp_mask: GFP flags for the allocation
2627  *
2628  * Like alloc_pages_exact(), but try to allocate on node nid first before falling
2629  * back.
2630  * Note this is not alloc_pages_exact_node() which allocates on a specific node,
2631  * but is not exact.
2632  */
2633 void *alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
2634 {
2635         unsigned order = get_order(size);
2636         struct page *p = alloc_pages_node(nid, gfp_mask, order);
2637         if (!p)
2638                 return NULL;
2639         return make_alloc_exact((unsigned long)page_address(p), order, size);
2640 }
2641 EXPORT_SYMBOL(alloc_pages_exact_nid);
2642 
2643 /**
2644  * free_pages_exact - release memory allocated via alloc_pages_exact()
2645  * @virt: the value returned by alloc_pages_exact.
2646  * @size: size of allocation, same value as passed to alloc_pages_exact().
2647  *
2648  * Release the memory allocated by a previous call to alloc_pages_exact.
2649  */
2650 void free_pages_exact(void *virt, size_t size)
2651 {
2652         unsigned long addr = (unsigned long)virt;
2653         unsigned long end = addr + PAGE_ALIGN(size);
2654 
2655         while (addr < end) {
2656                 free_page(addr);
2657                 addr += PAGE_SIZE;
2658         }
2659 }
2660 EXPORT_SYMBOL(free_pages_exact);
2661 
2662 static unsigned int nr_free_zone_pages(int offset)
2663 {
2664         struct zoneref *z;
2665         struct zone *zone;
2666 
2667         /* Just pick one node, since fallback list is circular */
2668         unsigned int sum = 0;
2669 
2670         struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
2671 
2672         for_each_zone_zonelist(zone, z, zonelist, offset) {
2673                 unsigned long size = zone->present_pages;
2674                 unsigned long high = high_wmark_pages(zone);
2675                 if (size > high)
2676                         sum += size - high;
2677         }
2678 
2679         return sum;
2680 }
2681 
2682 /*
2683  * Amount of free RAM allocatable within ZONE_DMA and ZONE_NORMAL
2684  */
2685 unsigned int nr_free_buffer_pages(void)
2686 {
2687         return nr_free_zone_pages(gfp_zone(GFP_USER));
2688 }
2689 EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
2690 
2691 /*
2692  * Amount of free RAM allocatable within all zones
2693  */
2694 unsigned int nr_free_pagecache_pages(void)
2695 {
2696         return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
2697 }
2698 
2699 static inline void show_node(struct zone *zone)
2700 {
2701         if (NUMA_BUILD)
2702                 printk("Node %d ", zone_to_nid(zone));
2703 }
2704 
2705 void si_meminfo(struct sysinfo *val)
2706 {
2707         val->totalram = totalram_pages;
2708         val->sharedram = 0;
2709         val->freeram = global_page_state(NR_FREE_PAGES);
2710         val->bufferram = nr_blockdev_pages();
2711         val->totalhigh = totalhigh_pages;
2712         val->freehigh = nr_free_highpages();
2713         val->mem_unit = PAGE_SIZE;
2714 }
2715 
2716 EXPORT_SYMBOL(si_meminfo);
2717 
2718 #ifdef CONFIG_NUMA
2719 void si_meminfo_node(struct sysinfo *val, int nid)
2720 {
2721         pg_data_t *pgdat = NODE_DATA(nid);
2722 
2723         val->totalram = pgdat->node_present_pages;
2724         val->freeram = node_page_state(nid, NR_FREE_PAGES);
2725 #ifdef CONFIG_HIGHMEM
2726         val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
2727         val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
2728                         NR_FREE_PAGES);
2729 #else
2730         val->totalhigh = 0;
2731         val->freehigh = 0;
2732 #endif
2733         val->mem_unit = PAGE_SIZE;
2734 }
2735 #endif
2736 
2737 /*
2738  * Determine whether the node should be displayed or not, depending on whether
2739  * SHOW_MEM_FILTER_NODES was passed to show_free_areas().
2740  */
2741 bool skip_free_areas_node(unsigned int flags, int nid)
2742 {
2743         bool ret = false;
2744         unsigned int cpuset_mems_cookie;
2745 
2746         if (!(flags & SHOW_MEM_FILTER_NODES))
2747                 goto out;
2748 
2749         do {
2750                 cpuset_mems_cookie = get_mems_allowed();
2751                 ret = !node_isset(nid, cpuset_current_mems_allowed);
2752         } while (!put_mems_allowed(cpuset_mems_cookie));
2753 out:
2754         return ret;
2755 }
2756 
2757 #define K(x) ((x) << (PAGE_SHIFT-10))
2758 
2759 /*
2760  * Show free area list (used inside shift_scroll-lock stuff)
2761  * We also calculate the percentage fragmentation. We do this by counting the
2762  * memory on each free list with the exception of the first item on the list.
2763  * Suppresses nodes that are not allowed by current's cpuset if
2764  * SHOW_MEM_FILTER_NODES is passed.
2765  */
2766 void show_free_areas(unsigned int filter)
2767 {
2768         int cpu;
2769         struct zone *zone;
2770 
2771         for_each_populated_zone(zone) {
2772                 if (skip_free_areas_node(filter, zone_to_nid(zone)))
2773                         continue;
2774                 show_node(zone);
2775                 printk("%s per-cpu:\n", zone->name);
2776 
2777                 for_each_online_cpu(cpu) {
2778                         struct per_cpu_pageset *pageset;
2779 
2780                         pageset = per_cpu_ptr(zone->pageset, cpu);
2781 
2782                         printk("CPU %4d: hi:%5d, btch:%4d usd:%4d\n",
2783                                cpu, pageset->pcp.high,
2784                                pageset->pcp.batch, pageset->pcp.count);
2785                 }
2786         }
2787 
2788         printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
2789                 " active_file:%lu inactive_file:%lu isolated_file:%lu\n"
2790                 " unevictable:%lu"
2791                 " dirty:%lu writeback:%lu unstable:%lu\n"
2792                 " free:%lu slab_reclaimable:%lu slab_unreclaimable:%lu\n"
2793                 " mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n",
2794                 global_page_state(NR_ACTIVE_ANON),
2795                 global_page_state(NR_INACTIVE_ANON),
2796                 global_page_state(NR_ISOLATED_ANON),
2797                 global_page_state(NR_ACTIVE_FILE),
2798                 global_page_state(NR_INACTIVE_FILE),
2799                 global_page_state(NR_ISOLATED_FILE),
2800                 global_page_state(NR_UNEVICTABLE),
2801                 global_page_state(NR_FILE_DIRTY),
2802                 global_page_state(NR_WRITEBACK),
2803                 global_page_state(NR_UNSTABLE_NFS),
2804                 global_page_state(NR_FREE_PAGES),
2805                 global_page_state(NR_SLAB_RECLAIMABLE),
2806                 global_page_state(NR_SLAB_UNRECLAIMABLE),
2807                 global_page_state(NR_FILE_MAPPED),
2808                 global_page_state(NR_SHMEM),
2809                 global_page_state(NR_PAGETABLE),
2810                 global_page_state(NR_BOUNCE));
2811 
2812         for_each_populated_zone(zone) {
2813                 int i;
2814 
2815                 if (skip_free_areas_node(filter, zone_to_nid(zone)))
2816                         continue;
2817                 show_node(zone);
2818                 printk("%s"
2819                         " free:%lukB"
2820                         " min:%lukB"
2821                         " low:%lukB"
2822                         " high:%lukB"
2823                         " active_anon:%lukB"
2824                         " inactive_anon:%lukB"
2825                         " active_file:%lukB"
2826                         " inactive_file:%lukB"
2827                         " unevictable:%lukB"
2828                         " isolated(anon):%lukB"
2829                         " isolated(file):%lukB"
2830                         " present:%lukB"
2831                         " mlocked:%lukB"
2832                         " dirty:%lukB"
2833                         " writeback:%lukB"
2834                         " mapped:%lukB"
2835                         " shmem:%lukB"
2836                         " slab_reclaimable:%lukB"
2837                         " slab_unreclaimable:%lukB"
2838                         " kernel_stack:%lukB"
2839                         " pagetables:%lukB"
2840                         " unstable:%lukB"
2841                         " bounce:%lukB"
2842                         " writeback_tmp:%lukB"
2843                         " pages_scanned:%lu"
2844                         " all_unreclaimable? %s"
2845                         "\n",
2846                         zone->name,
2847                         K(zone_page_state(zone, NR_FREE_PAGES)),
2848                         K(min_wmark_pages(zone)),
2849                         K(low_wmark_pages(zone)),
2850                         K(high_wmark_pages(zone)),
2851                         K(zone_page_state(zone, NR_ACTIVE_ANON)),
2852                         K(zone_page_state(zone, NR_INACTIVE_ANON)),
2853                         K(zone_page_state(zone, NR_ACTIVE_FILE)),
2854                         K(zone_page_state(zone, NR_INACTIVE_FILE)),
2855                         K(zone_page_state(zone, NR_UNEVICTABLE)),
2856                         K(zone_page_state(zone, NR_ISOLATED_ANON)),
2857                         K(zone_page_state(zone, NR_ISOLATED_FILE)),
2858                         K(zone->present_pages),
2859                         K(zone_page_state(zone, NR_MLOCK)),
2860                         K(zone_page_state(zone, NR_FILE_DIRTY)),
2861                         K(zone_page_state(zone, NR_WRITEBACK)),
2862                         K(zone_page_state(zone, NR_FILE_MAPPED)),
2863                         K(zone_page_state(zone, NR_SHMEM)),
2864                         K(zone_page_state(zone, NR_SLAB_RECLAIMABLE)),
2865                         K(zone_page_state(zone, NR_SLAB_UNRECLAIMABLE)),
2866                         zone_page_state(zone, NR_KERNEL_STACK) *
2867                                 THREAD_SIZE / 1024,
2868                         K(zone_page_state(zone, NR_PAGETABLE)),
2869                         K(zone_page_state(zone, NR_UNSTABLE_NFS)),
2870                         K(zone_page_state(zone, NR_BOUNCE)),
2871                         K(zone_page_state(zone, NR_WRITEBACK_TEMP)),
2872                         zone->pages_scanned,
2873                         (zone->all_unreclaimable ? "yes" : "no")
2874                         );
2875                 printk("lowmem_reserve[]:");
2876                 for (i = 0; i < MAX_NR_ZONES; i++)
2877                         printk(" %lu", zone->lowmem_reserve[i]);
2878                 printk("\n");
2879         }
2880 
2881         for_each_populated_zone(zone) {
2882                 unsigned long nr[MAX_ORDER], flags, order, total = 0;
2883 
2884                 if (skip_free_areas_node(filter, zone_to_nid(zone)))
2885                         continue;
2886                 show_node(zone);
2887                 printk("%s: ", zone->name);
2888 
2889                 spin_lock_irqsave(&zone->lock, flags);
2890                 for (order = 0; order < MAX_ORDER; order++) {
2891                         nr[order] = zone->free_area[order].nr_free;
2892                         total += nr[order] << order;
2893                 }
2894                 spin_unlock_irqrestore(&zone->lock, flags);
2895                 for (order = 0; order < MAX_ORDER; order++)
2896                         printk("%lu*%lukB ", nr[order], K(1UL) << order);
2897                 printk("= %lukB\n", K(total));
2898         }
2899 
2900         printk("%ld total pagecache pages\n", global_page_state(NR_FILE_PAGES));
2901 
2902         show_swap_cache_info();
2903 }
2904 
2905 static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
2906 {
2907         zoneref->zone = zone;
2908         zoneref->zone_idx = zone_idx(zone);
2909 }
2910 
2911 /*
2912  * Builds allocation fallback zone lists.
2913  *
2914  * Add all populated zones of a node to the zonelist.
2915  */
2916 static int build_zonelists_node(pg_data_t *pgdat, struct zonelist *zonelist,
2917                                 int nr_zones, enum zone_type zone_type)
2918 {
2919         struct zone *zone;
2920 
2921         BUG_ON(zone_type >= MAX_NR_ZONES);
2922         zone_type++;
2923 
2924         do {
2925                 zone_type--;
2926                 zone = pgdat->node_zones + zone_type;
2927                 if (populated_zone(zone)) {
2928                         zoneref_set_zone(zone,
2929                                 &zonelist->_zonerefs[nr_zones++]);
2930                         check_highest_zone(zone_type);
2931                 }
2932 
2933         } while (zone_type);
2934         return nr_zones;
2935 }
2936 
2937 
2938 /*
2939  *  zonelist_order:
2940  *  0 = automatic detection of better ordering.
2941  *  1 = order by ([node] distance, -zonetype)
2942  *  2 = order by (-zonetype, [node] distance)
2943  *
2944  *  If not NUMA, ZONELIST_ORDER_ZONE and ZONELIST_ORDER_NODE will create
2945  *  the same zonelist. So only NUMA can configure this param.
2946  */
2947 #define ZONELIST_ORDER_DEFAULT  0
2948 #define ZONELIST_ORDER_NODE     1
2949 #define ZONELIST_ORDER_ZONE     2
2950 
2951 /* zonelist order in the kernel.
2952  * set_zonelist_order() will set this to NODE or ZONE.
2953  */
2954 static int current_zonelist_order = ZONELIST_ORDER_DEFAULT;
2955 static char zonelist_order_name[3][8] = {"Default", "Node", "Zone"};
2956 
2957 
2958 #ifdef CONFIG_NUMA
2959 /* The value user specified ....changed by config */
2960 static int user_zonelist_order = ZONELIST_ORDER_DEFAULT;
2961 /* string for sysctl */
2962 #define NUMA_ZONELIST_ORDER_LEN 16
2963 char numa_zonelist_order[16] = "default";
2964 
2965 /*
2966  * interface for configure zonelist ordering.
2967  * command line option "numa_zonelist_order"
2968  *      = "[dD]efault   - default, automatic configuration.
2969  *      = "[nN]ode      - order by node locality, then by zone within node
2970  *      = "[zZ]one      - order by zone, then by locality within zone
2971  */
2972 
2973 static int __parse_numa_zonelist_order(char *s)
2974 {
2975         if (*s == 'd' || *s == 'D') {
2976                 user_zonelist_order = ZONELIST_ORDER_DEFAULT;
2977         } else if (*s == 'n' || *s == 'N') {
2978                 user_zonelist_order = ZONELIST_ORDER_NODE;
2979         } else if (*s == 'z' || *s == 'Z') {
2980                 user_zonelist_order = ZONELIST_ORDER_ZONE;
2981         } else {
2982                 printk(KERN_WARNING
2983                         "Ignoring invalid numa_zonelist_order value:  "
2984                         "%s\n", s);
2985                 return -EINVAL;
2986         }
2987         return 0;
2988 }
2989 
2990 static __init int setup_numa_zonelist_order(char *s)
2991 {
2992         int ret;
2993 
2994         if (!s)
2995                 return 0;
2996 
2997         ret = __parse_numa_zonelist_order(s);
2998         if (ret == 0)
2999                 strlcpy(numa_zonelist_order, s, NUMA_ZONELIST_ORDER_LEN);
3000 
3001         return ret;
3002 }
3003 early_param("numa_zonelist_order", setup_numa_zonelist_order);
3004 
3005 /*
3006  * sysctl handler for numa_zonelist_order
3007  */
3008 int numa_zonelist_order_handler(ctl_table *table, int write,
3009                 void __user *buffer, size_t *length,
3010                 loff_t *ppos)
3011 {
3012         char saved_string[NUMA_ZONELIST_ORDER_LEN];
3013         int ret;
3014         static DEFINE_MUTEX(zl_order_mutex);
3015 
3016         mutex_lock(&zl_order_mutex);
3017         if (write)
3018                 strcpy(saved_string, (char*)table->data);
3019         ret = proc_dostring(table, write, buffer, length, ppos);
3020         if (ret)
3021                 goto out;
3022         if (write) {
3023                 int oldval = user_zonelist_order;
3024                 if (__parse_numa_zonelist_order((char*)table->data)) {
3025                         /*
3026                          * bogus value.  restore saved string
3027                          */
3028                         strncpy((char*)table->data, saved_string,
3029                                 NUMA_ZONELIST_ORDER_LEN);
3030                         user_zonelist_order = oldval;
3031                 } else if (oldval != user_zonelist_order) {
3032                         mutex_lock(&zonelists_mutex);
3033                         build_all_zonelists(NULL);
3034                         mutex_unlock(&zonelists_mutex);
3035                 }
3036         }
3037 out:
3038         mutex_unlock(&zl_order_mutex);
3039         return ret;
3040 }
3041 
3042 
3043 #define MAX_NODE_LOAD (nr_online_nodes)
3044 static int node_load[MAX_NUMNODES];
3045 
3046 /**
3047  * find_next_best_node - find the next node that should appear in a given node's fallback list
3048  * @node: node whose fallback list we're appending
3049  * @used_node_mask: nodemask_t of already used nodes
3050  *
3051  * We use a number of factors to determine which is the next node that should
3052  * appear on a given node's fallback list.  The node should not have appeared
3053  * already in @node's fallback list, and it should be the next closest node
3054  * according to the distance array (which contains arbitrary distance values
3055  * from each node to each node in the system), and should also prefer nodes
3056  * with no CPUs, since presumably they'll have very little allocation pressure
3057  * on them otherwise.
3058  * It returns -1 if no node is found.
3059  */
3060 static int find_next_best_node(int node, nodemask_t *used_node_mask)
3061 {
3062         int n, val;
3063         int min_val = INT_MAX;
3064         int best_node = -1;
3065         const struct cpumask *tmp = cpumask_of_node(0);
3066 
3067         /* Use the local node if we haven't already */
3068         if (!node_isset(node, *used_node_mask)) {
3069                 node_set(node, *used_node_mask);
3070                 return node;
3071         }
3072 
3073         for_each_node_state(n, N_HIGH_MEMORY) {
3074 
3075                 /* Don't want a node to appear more than once */
3076                 if (node_isset(n, *used_node_mask))
3077                         continue;
3078 
3079                 /* Use the distance array to find the distance */
3080                 val = node_distance(node, n);
3081 
3082                 /* Penalize nodes under us ("prefer the next node") */
3083                 val += (n < node);
3084 
3085                 /* Give preference to headless and unused nodes */
3086                 tmp = cpumask_of_node(n);
3087                 if (!cpumask_empty(tmp))
3088                         val += PENALTY_FOR_NODE_WITH_CPUS;
3089 
3090                 /* Slight preference for less loaded node */
3091                 val *= (MAX_NODE_LOAD*MAX_NUMNODES);
3092                 val += node_load[n];
3093 
3094                 if (val < min_val) {
3095                         min_val = val;
3096                         best_node = n;
3097                 }
3098         }
3099 
3100         if (best_node >= 0)
3101                 node_set(best_node, *used_node_mask);
3102 
3103         return best_node;
3104 }
3105 
3106 
3107 /*
3108  * Build zonelists ordered by node and zones within node.
3109  * This results in maximum locality--normal zone overflows into local
3110  * DMA zone, if any--but risks exhausting DMA zone.
3111  */
3112 static void build_zonelists_in_node_order(pg_data_t *pgdat, int node)
3113 {
3114         int j;
3115         struct zonelist *zonelist;
3116 
3117         zonelist = &pgdat->node_zonelists[0];
3118         for (j = 0; zonelist->_zonerefs[j].zone != NULL; j++)
3119                 ;
3120         j = build_zonelists_node(NODE_DATA(node), zonelist, j,
3121                                                         MAX_NR_ZONES - 1);
3122         zonelist->_zonerefs[j].zone = NULL;
3123         zonelist->_zonerefs[j].zone_idx = 0;
3124 }
3125 
3126 /*
3127  * Build gfp_thisnode zonelists
3128  */
3129 static void build_thisnode_zonelists(pg_data_t *pgdat)
3130 {
3131         int j;
3132         struct zonelist *zonelist;
3133 
3134         zonelist = &pgdat->node_zonelists[1];
3135         j = build_zonelists_node(pgdat, zonelist, 0, MAX_NR_ZONES - 1);
3136         zonelist->_zonerefs[j].zone = NULL;
3137         zonelist->_zonerefs[j].zone_idx = 0;
3138 }
3139 
3140 /*
3141  * Build zonelists ordered by zone and nodes within zones.
3142  * This results in conserving DMA zone[s] until all Normal memory is
3143  * exhausted, but results in overflowing to remote node while memory
3144  * may still exist in local DMA zone.
3145  */
3146 static int node_order[MAX_NUMNODES];
3147 
3148 static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
3149 {
3150         int pos, j, node;
3151         int zone_type;          /* needs to be signed */
3152         struct zone *z;
3153         struct zonelist *zonelist;
3154 
3155         zonelist = &pgdat->node_zonelists[0];
3156         pos = 0;
3157         for (zone_type = MAX_NR_ZONES - 1; zone_type >= 0; zone_type--) {
3158                 for (j = 0; j < nr_nodes; j++) {
3159                         node = node_order[j];
3160                         z = &NODE_DATA(node)->node_zones[zone_type];
3161                         if (populated_zone(z)) {
3162                                 zoneref_set_zone(z,
3163                                         &zonelist->_zonerefs[pos++]);
3164                                 check_highest_zone(zone_type);
3165                         }
3166                 }
3167         }
3168         zonelist->_zonerefs[pos].zone = NULL;
3169         zonelist->_zonerefs[pos].zone_idx = 0;
3170 }
3171 
3172 static int default_zonelist_order(void)
3173 {
3174         int nid, zone_type;
3175         unsigned long low_kmem_size,total_size;
3176         struct zone *z;
3177         int average_size;
3178         /*
3179          * ZONE_DMA and ZONE_DMA32 can be very small area in the system.
3180          * If they are really small and used heavily, the system can fall
3181          * into OOM very easily.
3182          * This function detect ZONE_DMA/DMA32 size and configures zone order.
3183          */
3184         /* Is there ZONE_NORMAL ? (ex. ppc has only DMA zone..) */
3185         low_kmem_size = 0;
3186         total_size = 0;
3187         for_each_online_node(nid) {
3188                 for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
3189                         z = &NODE_DATA(nid)->node_zones[zone_type];
3190                         if (populated_zone(z)) {
3191                                 if (zone_type < ZONE_NORMAL)
3192                                         low_kmem_size += z->present_pages;
3193                                 total_size += z->present_pages;
3194                         } else if (zone_type == ZONE_NORMAL) {
3195                                 /*
3196                                  * If any node has only lowmem, then node order
3197                                  * is preferred to allow kernel allocations
3198                                  * locally; otherwise, they can easily infringe
3199                                  * on other nodes when there is an abundance of
3200                                  * lowmem available to allocate from.
3201                                  */
3202                                 return ZONELIST_ORDER_NODE;
3203                         }
3204                 }
3205         }
3206         if (!low_kmem_size ||  /* there are no DMA area. */
3207             low_kmem_size > total_size/2) /* DMA/DMA32 is big. */
3208                 return ZONELIST_ORDER_NODE;
3209         /*
3210          * look into each node's config.
3211          * If there is a node whose DMA/DMA32 memory is very big area on
3212          * local memory, NODE_ORDER may be suitable.
3213          */
3214         average_size = total_size /
3215                                 (nodes_weight(node_states[N_HIGH_MEMORY]) + 1);
3216         for_each_online_node(nid) {
3217                 low_kmem_size = 0;
3218                 total_size = 0;
3219                 for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
3220                         z = &NODE_DATA(nid)->node_zones[zone_type];
3221                         if (populated_zone(z)) {
3222                                 if (zone_type < ZONE_NORMAL)
3223                                         low_kmem_size += z->present_pages;
3224                                 total_size += z->present_pages;
3225                         }
3226                 }
3227                 if (low_kmem_size &&
3228                     total_size > average_size && /* ignore small node */
3229                     low_kmem_size > total_size * 70/100)
3230                         return ZONELIST_ORDER_NODE;
3231         }
3232         return ZONELIST_ORDER_ZONE;
3233 }
3234 
3235 static void set_zonelist_order(void)
3236 {
3237         if (user_zonelist_order == ZONELIST_ORDER_DEFAULT)
3238                 current_zonelist_order = default_zonelist_order();
3239         else
3240                 current_zonelist_order = user_zonelist_order;
3241 }
3242 
3243 static void build_zonelists(pg_data_t *pgdat)
3244 {
3245         int j, node, load;
3246         enum zone_type i;
3247         nodemask_t used_mask;
3248         int local_node, prev_node;
3249         struct zonelist *zonelist;
3250         int order = current_zonelist_order;
3251 
3252         /* initialize zonelists */
3253         for (i = 0; i < MAX_ZONELISTS; i++) {
3254                 zonelist = pgdat->node_zonelists + i;
3255                 zonelist->_zonerefs[0].zone = NULL;
3256                 zonelist->_zonerefs[0].zone_idx = 0;
3257         }
3258 
3259         /* NUMA-aware ordering of nodes */
3260         local_node = pgdat->node_id;
3261         load = nr_online_nodes;
3262         prev_node = local_node;
3263         nodes_clear(used_mask);
3264 
3265         memset(node_order, 0, sizeof(node_order));
3266         j = 0;
3267 
3268         while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
3269                 int distance = node_distance(local_node, node);
3270 
3271                 /*
3272                  * If another node is sufficiently far away then it is better
3273                  * to reclaim pages in a zone before going off node.
3274                  */
3275                 if (distance > RECLAIM_DISTANCE)
3276                         zone_reclaim_mode = 1;
3277 
3278                 /*
3279                  * We don't want to pressure a particular node.
3280                  * So adding penalty to the first node in same
3281                  * distance group to make it round-robin.
3282                  */
3283                 if (distance != node_distance(local_node, prev_node))
3284                         node_load[node] = load;
3285 
3286                 prev_node = node;
3287                 load--;
3288                 if (order == ZONELIST_ORDER_NODE)
3289                         build_zonelists_in_node_order(pgdat, node);
3290                 else
3291                         node_order[j++] = node; /* remember order */
3292         }
3293 
3294         if (order == ZONELIST_ORDER_ZONE) {
3295                 /* calculate node order -- i.e., DMA last! */
3296                 build_zonelists_in_zone_order(pgdat, j);
3297         }
3298 
3299         build_thisnode_zonelists(pgdat);
3300 }
3301 
3302 /* Construct the zonelist performance cache - see further mmzone.h */
3303 static void build_zonelist_cache(pg_data_t *pgdat)
3304 {
3305         struct zonelist *zonelist;
3306         struct zonelist_cache *zlc;
3307         struct zoneref *z;
3308 
3309         zonelist = &pgdat->node_zonelists[0];
3310         zonelist->zlcache_ptr = zlc = &zonelist->zlcache;
3311         bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
3312         for (z = zonelist->_zonerefs; z->zone; z++)
3313                 zlc->z_to_n[z - zonelist->_zonerefs] = zonelist_node_idx(z);
3314 }
3315 
3316 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
3317 /*
3318  * Return node id of node used for "local" allocations.
3319  * I.e., first node id of first zone in arg node's generic zonelist.
3320  * Used for initializing percpu 'numa_mem', which is used primarily
3321  * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
3322  */
3323 int local_memory_node(int node)
3324 {
3325         struct zone *zone;
3326 
3327         (void)first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
3328                                    gfp_zone(GFP_KERNEL),
3329                                    NULL,
3330                                    &zone);
3331         return zone->node;
3332 }
3333 #endif
3334 
3335 #else   /* CONFIG_NUMA */
3336 
3337 static void set_zonelist_order(void)
3338 {
3339         current_zonelist_order = ZONELIST_ORDER_ZONE;
3340 }
3341 
3342 static void build_zonelists(pg_data_t *pgdat)
3343 {
3344         int node, local_node;
3345         enum zone_type j;
3346         struct zonelist *zonelist;
3347 
3348         local_node = pgdat->node_id;
3349 
3350         zonelist = &pgdat->node_zonelists[0];
3351         j = build_zonelists_node(pgdat, zonelist, 0, MAX_NR_ZONES - 1);
3352 
3353         /*
3354          * Now we build the zonelist so that it contains the zones
3355          * of all the other nodes.
3356          * We don't want to pressure a particular node, so when
3357          * building the zones for node N, we make sure that the
3358          * zones coming right after the local ones are those from
3359          * node N+1 (modulo N)
3360          */
3361         for (node = local_node + 1; node < MAX_NUMNODES; node++) {
3362                 if (!node_online(node))
3363                         continue;
3364                 j = build_zonelists_node(NODE_DATA(node), zonelist, j,
3365                                                         MAX_NR_ZONES - 1);
3366         }
3367         for (node = 0; node < local_node; node++) {
3368                 if (!node_online(node))
3369                         continue;
3370                 j = build_zonelists_node(NODE_DATA(node), zonelist, j,
3371                                                         MAX_NR_ZONES - 1);
3372         }
3373 
3374         zonelist->_zonerefs[j].zone = NULL;
3375         zonelist->_zonerefs[j].zone_idx = 0;
3376 }
3377 
3378 /* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
3379 static void build_zonelist_cache(pg_data_t *pgdat)
3380 {
3381         pgdat->node_zonelists[0].zlcache_ptr = NULL;
3382 }
3383 
3384 #endif  /* CONFIG_NUMA */
3385 
3386 /*
3387  * Boot pageset table. One per cpu which is going to be used for all
3388  * zones and all nodes. The parameters will be set in such a way
3389  * that an item put on a list will immediately be handed over to
3390  * the buddy list. This is safe since pageset manipulation is done
3391  * with interrupts disabled.
3392  *
3393  * The boot_pagesets must be kept even after bootup is complete for
3394  * unused processors and/or zones. They do play a role for bootstrapping
3395  * hotplugged processors.
3396  *
3397  * zoneinfo_show() and maybe other functions do
3398  * not check if the processor is online before following the pageset pointer.
3399  * Other parts of the kernel may not check if the zone is available.
3400  */
3401 static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
3402 static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
3403 static void setup_zone_pageset(struct zone *zone);
3404 
3405 /*
3406  * Global mutex to protect against size modification of zonelists
3407  * as well as to serialize pageset setup for the new populated zone.
3408  */
3409 DEFINE_MUTEX(zonelists_mutex);
3410 
3411 /* return values int ....just for stop_machine() */
3412 static __init_refok int __build_all_zonelists(void *data)
3413 {
3414         int nid;
3415         int cpu;
3416 
3417 #ifdef CONFIG_NUMA
3418         memset(node_load, 0, sizeof(node_load));
3419 #endif
3420         for_each_online_node(nid) {
3421                 pg_data_t *pgdat = NODE_DATA(nid);
3422 
3423                 build_zonelists(pgdat);
3424                 build_zonelist_cache(pgdat);
3425         }
3426 
3427         /*
3428          * Initialize the boot_pagesets that are going to be used
3429          * for bootstrapping processors. The real pagesets for
3430          * each zone will be allocated later when the per cpu
3431          * allocator is available.
3432          *
3433          * boot_pagesets are used also for bootstrapping offline
3434          * cpus if the system is already booted because the pagesets
3435          * are needed to initialize allocators on a specific cpu too.
3436          * F.e. the percpu allocator needs the page allocator which
3437          * needs the percpu allocator in order to allocate its pagesets
3438          * (a chicken-egg dilemma).
3439          */
3440         for_each_possible_cpu(cpu) {
3441                 setup_pageset(&per_cpu(boot_pageset, cpu), 0);
3442 
3443 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
3444                 /*
3445                  * We now know the "local memory node" for each node--
3446                  * i.e., the node of the first zone in the generic zonelist.
3447                  * Set up numa_mem percpu variable for on-line cpus.  During
3448                  * boot, only the boot cpu should be on-line;  we'll init the
3449                  * secondary cpus' numa_mem as they come on-line.  During
3450                  * node/memory hotplug, we'll fixup all on-line cpus.
3451                  */
3452                 if (cpu_online(cpu))
3453                         set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
3454 #endif
3455         }
3456 
3457         return 0;
3458 }
3459 
3460 /*
3461  * Called with zonelists_mutex held always
3462  * unless system_state == SYSTEM_BOOTING.
3463  */
3464 void __ref build_all_zonelists(void *data)
3465 {
3466         set_zonelist_order();
3467 
3468         if (system_state == SYSTEM_BOOTING) {
3469                 __build_all_zonelists(NULL);
3470                 mminit_verify_zonelist();
3471                 cpuset_init_current_mems_allowed();
3472         } else {
3473                 /* we have to stop all cpus to guarantee there is no user
3474                    of zonelist */
3475 #ifdef CONFIG_MEMORY_HOTPLUG
3476                 if (data)
3477                         setup_zone_pageset((struct zone *)data);
3478 #endif
3479                 stop_machine(__build_all_zonelists, NULL, NULL);
3480                 /* cpuset refresh routine should be here */
3481         }
3482         vm_total_pages = nr_free_pagecache_pages();
3483         /*
3484          * Disable grouping by mobility if the number of pages in the
3485          * system is too low to allow the mechanism to work. It would be
3486          * more accurate, but expensive to check per-zone. This check is
3487          * made on memory-hotadd so a system can start with mobility
3488          * disabled and enable it later
3489          */
3490         if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
3491                 page_group_by_mobility_disabled = 1;
3492         else
3493                 page_group_by_mobility_disabled = 0;
3494 
3495         printk("Built %i zonelists in %s order, mobility grouping %s.  "
3496                 "Total pages: %ld\n",
3497                         nr_online_nodes,
3498                         zonelist_order_name[current_zonelist_order],
3499                         page_group_by_mobility_disabled ? "off" : "on",
3500                         vm_total_pages);
3501 #ifdef CONFIG_NUMA
3502         printk("Policy zone: %s\n", zone_names[policy_zone]);
3503 #endif
3504 }
3505 
3506 /*
3507  * Helper functions to size the waitqueue hash table.
3508  * Essentially these want to choose hash table sizes sufficiently
3509  * large so that collisions trying to wait on pages are rare.
3510  * But in fact, the number of active page waitqueues on typical
3511  * systems is ridiculously low, less than 200. So this is even
3512  * conservative, even though it seems large.
3513  *
3514  * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to
3515  * waitqueues, i.e. the size of the waitq table given the number of pages.
3516  */
3517 #define PAGES_PER_WAITQUEUE     256
3518 
3519 #ifndef CONFIG_MEMORY_HOTPLUG
3520 static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
3521 {
3522         unsigned long size = 1;
3523 
3524         pages /= PAGES_PER_WAITQUEUE;
3525 
3526         while (size < pages)
3527                 size <<= 1;
3528 
3529         /*
3530          * Once we have dozens or even hundreds of threads sleeping
3531          * on IO we've got bigger problems than wait queue collision.
3532          * Limit the size of the wait table to a reasonable size.
3533          */
3534         size = min(size, 4096UL);
3535 
3536         return max(size, 4UL);
3537 }
3538 #else
3539 /*
3540  * A zone's size might be changed by hot-add, so it is not possible to determine
3541  * a suitable size for its wait_table.  So we use the maximum size now.
3542  *
3543  * The max wait table size = 4096 x sizeof(wait_queue_head_t).   ie:
3544  *
3545  *    i386 (preemption config)    : 4096 x 16 = 64Kbyte.
3546  *    ia64, x86-64 (no preemption): 4096 x 20 = 80Kbyte.
3547  *    ia64, x86-64 (preemption)   : 4096 x 24 = 96Kbyte.
3548  *
3549  * The maximum entries are prepared when a zone's memory is (512K + 256) pages
3550  * or more by the traditional way. (See above).  It equals:
3551  *
3552  *    i386, x86-64, powerpc(4K page size) : =  ( 2G + 1M)byte.
3553  *    ia64(16K page size)                 : =  ( 8G + 4M)byte.
3554  *    powerpc (64K page size)             : =  (32G +16M)byte.
3555  */
3556 static inline unsigned long wait_table_hash_nr_entries(unsigned long pages)
3557 {
3558         return 4096UL;
3559 }
3560 #endif
3561 
3562 /*
3563  * This is an integer logarithm so that shifts can be used later
3564  * to extract the more random high bits from the multiplicative
3565  * hash function before the remainder is taken.
3566  */
3567 static inline unsigned long wait_table_bits(unsigned long size)
3568 {
3569         return ffz(~size);
3570 }
3571 
3572 #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))
3573 
3574 /*
3575  * Check if a pageblock contains reserved pages
3576  */
3577 static int pageblock_is_reserved(unsigned long start_pfn, unsigned long end_pfn)
3578 {
3579         unsigned long pfn;
3580 
3581         for (pfn = start_pfn; pfn < end_pfn; pfn++) {
3582                 if (!pfn_valid_within(pfn) || PageReserved(pfn_to_page(pfn)))
3583                         return 1;
3584         }
3585         return 0;
3586 }
3587 
3588 /*
3589  * Mark a number of pageblocks as MIGRATE_RESERVE. The number
3590  * of blocks reserved is based on min_wmark_pages(zone). The memory within
3591  * the reserve will tend to store contiguous free pages. Setting min_free_kbytes
3592  * higher will lead to a bigger reserve which will get freed as contiguous
3593  * blocks as reclaim kicks in
3594  */
3595 static void setup_zone_migrate_reserve(struct zone *zone)
3596 {
3597         unsigned long start_pfn, pfn, end_pfn, block_end_pfn;
3598         struct page *page;
3599         unsigned long block_migratetype;
3600         int reserve;
3601 
3602         /*
3603          * Get the start pfn, end pfn and the number of blocks to reserve
3604          * We have to be careful to be aligned to pageblock_nr_pages to
3605          * make sure that we always check pfn_valid for the first page in
3606          * the block.
3607          */
3608         start_pfn = zone->zone_start_pfn;
3609         end_pfn = start_pfn + zone->spanned_pages;
3610         start_pfn = roundup(start_pfn, pageblock_nr_pages);
3611         reserve = roundup(min_wmark_pages(zone), pageblock_nr_pages) >>
3612                                                         pageblock_order;
3613 
3614         /*
3615          * Reserve blocks are generally in place to help high-order atomic
3616          * allocations that are short-lived. A min_free_kbytes value that
3617          * would result in more than 2 reserve blocks for atomic allocations
3618          * is assumed to be in place to help anti-fragmentation for the
3619          * future allocation of hugepages at runtime.
3620          */
3621         reserve = min(2, reserve);
3622 
3623         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
3624                 if (!pfn_valid(pfn))
3625                         continue;
3626                 page = pfn_to_page(pfn);
3627 
3628                 /* Watch out for overlapping nodes */
3629                 if (page_to_nid(page) != zone_to_nid(zone))
3630                         continue;
3631 
3632                 block_migratetype = get_pageblock_migratetype(page);
3633 
3634                 /* Only test what is necessary when the reserves are not met */
3635                 if (reserve > 0) {
3636                         /*
3637                          * Blocks with reserved pages will never free, skip
3638                          * them.
3639                          */
3640                         block_end_pfn = min(pfn + pageblock_nr_pages, end_pfn);
3641                         if (pageblock_is_reserved(pfn, block_end_pfn))
3642                                 continue;
3643 
3644                         /* If this block is reserved, account for it */
3645                         if (block_migratetype == MIGRATE_RESERVE) {
3646                                 reserve--;
3647                                 continue;
3648                         }
3649 
3650                         /* Suitable for reserving if this block is movable */
3651                         if (block_migratetype == MIGRATE_MOVABLE) {
3652                                 set_pageblock_migratetype(page,
3653                                                         MIGRATE_RESERVE);
3654                                 move_freepages_block(zone, page,
3655                                                         MIGRATE_RESERVE);
3656                                 reserve--;
3657                                 continue;
3658                         }
3659                 }
3660 
3661                 /*
3662                  * If the reserve is met and this is a previous reserved block,
3663                  * take it back
3664                  */
3665                 if (block_migratetype == MIGRATE_RESERVE) {
3666                         set_pageblock_migratetype(page, MIGRATE_MOVABLE);
3667                         move_freepages_block(zone, page, MIGRATE_MOVABLE);
3668                 }
3669         }
3670 }
3671 
3672 /*
3673  * Initially all pages are reserved - free ones are freed
3674  * up by free_all_bootmem() once the early boot process is
3675  * done. Non-atomic initialization, single-pass.
3676  */
3677 void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
3678                 unsigned long start_pfn, enum memmap_context context)
3679 {
3680         struct page *page;
3681         unsigned long end_pfn = start_pfn + size;
3682         unsigned long pfn;
3683         struct zone *z;
3684 
3685         if (highest_memmap_pfn < end_pfn - 1)
3686                 highest_memmap_pfn = end_pfn - 1;
3687 
3688         z = &NODE_DATA(nid)->node_zones[zone];
3689         for (pfn = start_pfn; pfn < end_pfn; pfn++) {
3690                 /*
3691                  * There can be holes in boot-time mem_map[]s
3692                  * handed to this function.  They do not
3693                  * exist on hotplugged memory.
3694                  */
3695                 if (context == MEMMAP_EARLY) {
3696                         if (!early_pfn_valid(pfn))
3697                                 continue;
3698                         if (!early_pfn_in_nid(pfn, nid))
3699                                 continue;
3700                 }
3701                 page = pfn_to_page(pfn);
3702                 set_page_links(page, zone, nid, pfn);
3703                 mminit_verify_page_links(page, zone, nid, pfn);
3704                 init_page_count(page);
3705                 reset_page_mapcount(page);
3706                 SetPageReserved(page);
3707                 /*
3708                  * Mark the block movable so that blocks are reserved for
3709                  * movable at startup. This will force kernel allocations
3710                  * to reserve their blocks rather than leaking throughout
3711                  * the address space during boot when many long-lived
3712                  * kernel allocations are made. Later some blocks near
3713                  * the start are marked MIGRATE_RESERVE by
3714                  * setup_zone_migrate_reserve()
3715                  *
3716                  * bitmap is created for zone's valid pfn range. but memmap
3717                  * can be created for invalid pages (for alignment)
3718                  * check here not to call set_pageblock_migratetype() against
3719                  * pfn out of zone.
3720                  */
3721                 if ((z->zone_start_pfn <= pfn)
3722                     && (pfn < z->zone_start_pfn + z->spanned_pages)
3723                     && !(pfn & (pageblock_nr_pages - 1)))
3724                         set_pageblock_migratetype(page, MIGRATE_MOVABLE);
3725 
3726                 INIT_LIST_HEAD(&page->lru);
3727 #ifdef WANT_PAGE_VIRTUAL
3728                 /* The shift won't overflow because ZONE_NORMAL is below 4G. */
3729                 if (!is_highmem_idx(zone))
3730                         set_page_address(page, __va(pfn << PAGE_SHIFT));
3731 #endif
3732         }
3733 }
3734 
3735 static void __meminit zone_init_free_lists(struct zone *zone)
3736 {
3737         int order, t;
3738         for_each_migratetype_order(order, t) {
3739                 INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
3740                 zone->free_area[order].nr_free = 0;
3741         }
3742 }
3743 
3744 #ifndef __HAVE_ARCH_MEMMAP_INIT
3745 #define memmap_init(size, nid, zone, start_pfn) \
3746         memmap_init_zone((size), (nid), (zone), (start_pfn), MEMMAP_EARLY)
3747 #endif
3748 
3749 static int zone_batchsize(struct zone *zone)
3750 {
3751 #ifdef CONFIG_MMU
3752         int batch;
3753 
3754         /*
3755          * The per-cpu-pages pools are set to around 1000th of the
3756          * size of the zone.  But no more than 1/2 of a meg.
3757          *
3758          * OK, so we don't know how big the cache is.  So guess.
3759          */
3760         batch = zone->present_pages / 1024;
3761         if (batch * PAGE_SIZE > 512 * 1024)
3762                 batch = (512 * 1024) / PAGE_SIZE;
3763         batch /= 4;             /* We effectively *= 4 below */
3764         if (batch < 1)
3765                 batch = 1;
3766 
3767         /*
3768          * Clamp the batch to a 2^n - 1 value. Having a power
3769          * of 2 value was found to be more likely to have
3770          * suboptimal cache aliasing properties in some cases.
3771          *
3772          * For example if 2 tasks are alternately allocating
3773          * batches of pages, one task can end up with a lot
3774          * of pages of one half of the possible page colors
3775          * and the other with pages of the other colors.
3776          */
3777         batch = rounddown_pow_of_two(batch + batch/2) - 1;
3778 
3779         return batch;
3780 
3781 #else
3782         /* The deferral and batching of frees should be suppressed under NOMMU
3783          * conditions.
3784          *
3785          * The problem is that NOMMU needs to be able to allocate large chunks
3786          * of contiguous memory as there's no hardware page translation to
3787          * assemble apparent contiguous memory from discontiguous pages.
3788          *
3789          * Queueing large contiguous runs of pages for batching, however,
3790          * causes the pages to actually be freed in smaller chunks.  As there
3791          * can be a significant delay between the individual batches being
3792          * recycled, this leads to the once large chunks of space being
3793          * fragmented and becoming unavailable for high-order allocations.
3794          */
3795         return 0;
3796 #endif
3797 }
3798 
3799 static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
3800 {
3801         struct per_cpu_pages *pcp;
3802         int migratetype;
3803 
3804         memset(p, 0, sizeof(*p));
3805 
3806         pcp = &p->pcp;
3807         pcp->count = 0;
3808         pcp->high = 6 * batch;
3809         pcp->batch = max(1UL, 1 * batch);
3810         for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
3811                 INIT_LIST_HEAD(&pcp->lists[migratetype]);
3812 }
3813 
3814 /*
3815  * setup_pagelist_highmark() sets the high water mark for hot per_cpu_pagelist
3816  * to the value high for the pageset p.
3817  */
3818 
3819 static void setup_pagelist_highmark(struct per_cpu_pageset *p,
3820                                 unsigned long high)
3821 {
3822         struct per_cpu_pages *pcp;
3823 
3824         pcp = &p->pcp;
3825         pcp->high = high;
3826         pcp->batch = max(1UL, high/4);
3827         if ((high/4) > (PAGE_SHIFT * 8))
3828                 pcp->batch = PAGE_SHIFT * 8;
3829 }
3830 
3831 static void setup_zone_pageset(struct zone *zone)
3832 {
3833         int cpu;
3834 
3835         zone->pageset = alloc_percpu(struct per_cpu_pageset);
3836 
3837         for_each_possible_cpu(cpu) {
3838                 struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu);
3839 
3840                 setup_pageset(pcp, zone_batchsize(zone));
3841 
3842                 if (percpu_pagelist_fraction)
3843                         setup_pagelist_highmark(pcp,
3844                                 (zone->present_pages /
3845                                         percpu_pagelist_fraction));
3846         }
3847 }
3848 
3849 /*
3850  * Allocate per cpu pagesets and initialize them.
3851  * Before this call only boot pagesets were available.
3852  */
3853 void __init setup_per_cpu_pageset(void)
3854 {
3855         struct zone *zone;
3856 
3857         for_each_populated_zone(zone)
3858                 setup_zone_pageset(zone);
3859 }
3860 
3861 static noinline __init_refok
3862 int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
3863 {
3864         int i;
3865         struct pglist_data *pgdat = zone->zone_pgdat;
3866         size_t alloc_size;
3867 
3868         /*
3869          * The per-page waitqueue mechanism uses hashed waitqueues
3870          * per zone.
3871          */
3872         zone->wait_table_hash_nr_entries =
3873                  wait_table_hash_nr_entries(zone_size_pages);
3874         zone->wait_table_bits =
3875                 wait_table_bits(zone->wait_table_hash_nr_entries);
3876         alloc_size = zone->wait_table_hash_nr_entries
3877                                         * sizeof(wait_queue_head_t);
3878 
3879         if (!slab_is_available()) {
3880                 zone->wait_table = (wait_queue_head_t *)
3881                         alloc_bootmem_node_nopanic(pgdat, alloc_size);
3882         } else {
3883                 /*
3884                  * This case means that a zone whose size was 0 gets new memory
3885                  * via memory hot-add.
3886                  * But it may be the case that a new node was hot-added.  In
3887                  * this case vmalloc() will not be able to use this new node's
3888                  * memory - this wait_table must be initialized to use this new
3889                  * node itself as well.
3890                  * To use this new node's memory, further consideration will be
3891                  * necessary.
3892                  */
3893                 zone->wait_table = vmalloc(alloc_size);
3894         }
3895         if (!zone->wait_table)
3896                 return -ENOMEM;
3897 
3898         for(i = 0; i < zone->wait_table_hash_nr_entries; ++i)
3899                 init_waitqueue_head(zone->wait_table + i);
3900 
3901         return 0;
3902 }
3903 
3904 static int __zone_pcp_update(void *data)
3905 {
3906         struct zone *zone = data;
3907         int cpu;
3908         unsigned long batch = zone_batchsize(zone), flags;
3909 
3910         for_each_possible_cpu(cpu) {
3911                 struct per_cpu_pageset *pset;
3912                 struct per_cpu_pages *pcp;
3913 
3914                 pset = per_cpu_ptr(zone->pageset, cpu);
3915                 pcp = &pset->pcp;
3916 
3917                 local_irq_save(flags);
3918                 free_pcppages_bulk(zone, pcp->count, pcp);
3919                 setup_pageset(pset, batch);
3920                 local_irq_restore(flags);
3921         }
3922         return 0;
3923 }
3924 
3925 void zone_pcp_update(struct zone *zone)
3926 {
3927         stop_machine(__zone_pcp_update, zone, NULL);
3928 }
3929 
3930 static __meminit void zone_pcp_init(struct zone *zone)
3931 {
3932         /*
3933          * per cpu subsystem is not up at this point. The following code
3934          * relies on the ability of the linker to provide the
3935          * offset of a (static) per cpu variable into the per cpu area.
3936          */
3937         zone->pageset = &boot_pageset;
3938 
3939         if (zone->present_pages)
3940                 printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%u\n",
3941                         zone->name, zone->present_pages,
3942                                          zone_batchsize(zone));
3943 }
3944 
3945 __meminit int init_currently_empty_zone(struct zone *zone,
3946                                         unsigned long zone_start_pfn,
3947                                         unsigned long size,
3948                                         enum memmap_context context)
3949 {
3950         struct pglist_data *pgdat = zone->zone_pgdat;
3951         int ret;
3952         ret = zone_wait_table_init(zone, size);
3953         if (ret)
3954                 return ret;
3955         pgdat->nr_zones = zone_idx(zone) + 1;
3956 
3957         zone->zone_start_pfn = zone_start_pfn;
3958 
3959         mminit_dprintk(MMINIT_TRACE, "memmap_init",
3960                         "Initialising map node %d zone %lu pfns %lu -> %lu\n",
3961                         pgdat->node_id,
3962                         (unsigned long)zone_idx(zone),
3963                         zone_start_pfn, (zone_start_pfn + size));
3964 
3965         zone_init_free_lists(zone);
3966 
3967         return 0;
3968 }
3969 
3970 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
3971 #ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
3972 /*
3973  * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
3974  * Architectures may implement their own version but if add_active_range()
3975  * was used and there are no special requirements, this is a convenient
3976  * alternative
3977  */
3978 int __meminit __early_pfn_to_nid(unsigned long pfn)
3979 {
3980         unsigned long start_pfn, end_pfn;
3981         int i, nid;
3982 
3983         for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
3984                 if (start_pfn <= pfn && pfn < end_pfn)
3985                         return nid;
3986         /* This is a memory hole */
3987         return -1;
3988 }
3989 #endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
3990 
3991 int __meminit early_pfn_to_nid(unsigned long pfn)
3992 {
3993         int nid;
3994 
3995         nid = __early_pfn_to_nid(pfn);
3996         if (nid >= 0)
3997                 return nid;
3998         /* just returns 0 */
3999         return 0;
4000 }
4001 
4002 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
4003 bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
4004 {
4005         int nid;
4006 
4007         nid = __early_pfn_to_nid(pfn);
4008         if (nid >= 0 && nid != node)
4009                 return false;
4010         return true;
4011 }
4012 #endif
4013 
4014 /**
4015  * free_bootmem_with_active_regions - Call free_bootmem_node for each active range
4016  * @nid: The node to free memory on. If MAX_NUMNODES, all nodes are freed.
4017  * @max_low_pfn: The highest PFN that will be passed to free_bootmem_node
4018  *
4019  * If an architecture guarantees that all ranges registered with
4020  * add_active_ranges() contain no holes and may be freed, this
4021  * this function may be used instead of calling free_bootmem() manually.
4022  */
4023 void __init free_bootmem_with_active_regions(int nid, unsigned long max_low_pfn)
4024 {
4025         unsigned long start_pfn, end_pfn;
4026         int i, this_nid;
4027 
4028         for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid) {
4029                 start_pfn = min(start_pfn, max_low_pfn);
4030                 end_pfn = min(end_pfn, max_low_pfn);
4031 
4032                 if (start_pfn < end_pfn)
4033                         free_bootmem_node(NODE_DATA(this_nid),
4034                                           PFN_PHYS(start_pfn),
4035                                           (end_pfn - start_pfn) << PAGE_SHIFT);
4036         }
4037 }
4038 
4039 /**
4040  * sparse_memory_present_with_active_regions - Call memory_present for each active range
4041  * @nid: The node to call memory_present for. If MAX_NUMNODES, all nodes will be used.
4042  *
4043  * If an architecture guarantees that all ranges registered with
4044  * add_active_ranges() contain no holes and may be freed, this
4045  * function may be used instead of calling memory_present() manually.
4046  */
4047 void __init sparse_memory_present_with_active_regions(int nid)
4048 {
4049         unsigned long start_pfn, end_pfn;
4050         int i, this_nid;
4051 
4052         for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid)
4053                 memory_present(this_nid, start_pfn, end_pfn);
4054 }
4055 
4056 /**
4057  * get_pfn_range_for_nid - Return the start and end page frames for a node
4058  * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
4059  * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
4060  * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
4061  *
4062  * It returns the start and end page frame of a node based on information
4063  * provided by an arch calling add_active_range(). If called for a node
4064  * with no available memory, a warning is printed and the start and end
4065  * PFNs will be 0.
4066  */
4067 void __meminit get_pfn_range_for_nid(unsigned int nid,
4068                         unsigned long *start_pfn, unsigned long *end_pfn)
4069 {
4070         unsigned long this_start_pfn, this_end_pfn;
4071         int i;
4072 
4073         *start_pfn = -1UL;
4074         *end_pfn = 0;
4075 
4076         for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
4077                 *start_pfn = min(*start_pfn, this_start_pfn);
4078                 *end_pfn = max(*end_pfn, this_end_pfn);
4079         }
4080 
4081         if (*start_pfn == -1UL)
4082                 *start_pfn = 0;
4083 }
4084 
4085 /*
4086  * This finds a zone that can be used for ZONE_MOVABLE pages. The
4087  * assumption is made that zones within a node are ordered in monotonic
4088  * increasing memory addresses so that the "highest" populated zone is used
4089  */
4090 static void __init find_usable_zone_for_movable(void)
4091 {
4092         int zone_index;
4093         for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
4094                 if (zone_index == ZONE_MOVABLE)
4095                         continue;
4096 
4097                 if (arch_zone_highest_possible_pfn[zone_index] >
4098                                 arch_zone_lowest_possible_pfn[zone_index])
4099                         break;
4100         }
4101 
4102         VM_BUG_ON(zone_index == -1);
4103         movable_zone = zone_index;
4104 }
4105 
4106 /*
4107  * The zone ranges provided by the architecture do not include ZONE_MOVABLE
4108  * because it is sized independent of architecture. Unlike the other zones,
4109  * the starting point for ZONE_MOVABLE is not fixed. It may be different
4110  * in each node depending on the size of each node and how evenly kernelcore
4111  * is distributed. This helper function adjusts the zone ranges
4112  * provided by the architecture for a given node by using the end of the
4113  * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
4114  * zones within a node are in order of monotonic increases memory addresses
4115  */
4116 static void __meminit adjust_zone_range_for_zone_movable(int nid,
4117                                         unsigned long zone_type,
4118                                         unsigned long node_start_pfn,
4119                                         unsigned long node_end_pfn,
4120                                         unsigned long *zone_start_pfn,
4121                                         unsigned long *zone_end_pfn)
4122 {
4123         /* Only adjust if ZONE_MOVABLE is on this node */
4124         if (zone_movable_pfn[nid]) {
4125                 /* Size ZONE_MOVABLE */
4126                 if (zone_type == ZONE_MOVABLE) {
4127                         *zone_start_pfn = zone_movable_pfn[nid];
4128                         *zone_end_pfn = min(node_end_pfn,
4129                                 arch_zone_highest_possible_pfn[movable_zone]);
4130 
4131                 /* Adjust for ZONE_MOVABLE starting within this range */
4132                 } else if (*zone_start_pfn < zone_movable_pfn[nid] &&
4133                                 *zone_end_pfn > zone_movable_pfn[nid]) {
4134                         *zone_end_pfn = zone_movable_pfn[nid];
4135 
4136                 /* Check if this whole range is within ZONE_MOVABLE */
4137                 } else if (*zone_start_pfn >= zone_movable_pfn[nid])
4138                         *zone_start_pfn = *zone_end_pfn;
4139         }
4140 }
4141 
4142 /*
4143  * Return the number of pages a zone spans in a node, including holes
4144  * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
4145  */
4146 static unsigned long __meminit zone_spanned_pages_in_node(int nid,
4147                                         unsigned long zone_type,
4148                                         unsigned long *ignored)
4149 {
4150         unsigned long node_start_pfn, node_end_pfn;
4151         unsigned long zone_start_pfn, zone_end_pfn;
4152 
4153         /* Get the start and end of the node and zone */
4154         get_pfn_range_for_nid(nid, &node_start_pfn, &node_end_pfn);
4155         zone_start_pfn = arch_zone_lowest_possible_pfn[zone_type];
4156         zone_end_pfn = arch_zone_highest_possible_pfn[zone_type];
4157         adjust_zone_range_for_zone_movable(nid, zone_type,
4158                                 node_start_pfn, node_end_pfn,
4159                                 &zone_start_pfn, &zone_end_pfn);
4160 
4161         /* Check that this node has pages within the zone's required range */
4162         if (zone_end_pfn < node_start_pfn || zone_start_pfn > node_end_pfn)
4163                 return 0;
4164 
4165         /* Move the zone boundaries inside the node if necessary */
4166         zone_end_pfn = min(zone_end_pfn, node_end_pfn);
4167         zone_start_pfn = max(zone_start_pfn, node_start_pfn);
4168 
4169         /* Return the spanned pages */
4170         return zone_end_pfn - zone_start_pfn;
4171 }
4172 
4173 /*
4174  * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
4175  * then all holes in the requested range will be accounted for.
4176  */
4177 unsigned long __meminit __absent_pages_in_range(int nid,
4178                                 unsigned long range_start_pfn,
4179                                 unsigned long range_end_pfn)
4180 {
4181         unsigned long nr_absent = range_end_pfn - range_start_pfn;
4182         unsigned long start_pfn, end_pfn;
4183         int i;
4184 
4185         for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
4186                 start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
4187                 end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
4188                 nr_absent -= end_pfn - start_pfn;
4189         }
4190         return nr_absent;
4191 }
4192 
4193 /**
4194  * absent_pages_in_range - Return number of page frames in holes within a range
4195  * @start_pfn: The start PFN to start searching for holes
4196  * @end_pfn: The end PFN to stop searching for holes
4197  *
4198  * It returns the number of pages frames in memory holes within a range.
4199  */
4200 unsigned long __init absent_pages_in_range(unsigned long start_pfn,
4201                                                         unsigned long end_pfn)
4202 {
4203         return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
4204 }
4205 
4206 /* Return the number of page frames in holes in a zone on a node */
4207 static unsigned long __meminit zone_absent_pages_in_node(int nid,
4208                                         unsigned long zone_type,
4209                                         unsigned long *ignored)
4210 {
4211         unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
4212         unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
4213         unsigned long node_start_pfn, node_end_pfn;
4214         unsigned long zone_start_pfn, zone_end_pfn;
4215 
4216         get_pfn_range_for_nid(nid, &node_start_pfn, &node_end_pfn);
4217         zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
4218         zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
4219 
4220         adjust_zone_range_for_zone_movable(nid, zone_type,
4221                         node_start_pfn, node_end_pfn,
4222                         &zone_start_pfn, &zone_end_pfn);
4223         return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
4224 }
4225 
4226 #else /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
4227 static inline unsigned long __meminit zone_spanned_pages_in_node(int nid,
4228                                         unsigned long zone_type,
4229                                         unsigned long *zones_size)
4230 {
4231         return zones_size[zone_type];
4232 }
4233 
4234 static inline unsigned long __meminit zone_absent_pages_in_node(int nid,
4235                                                 unsigned long zone_type,
4236                                                 unsigned long *zholes_size)
4237 {
4238         if (!zholes_size)
4239                 return 0;
4240 
4241         return zholes_size[zone_type];
4242 }
4243 
4244 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
4245 
4246 static void __meminit calculate_node_totalpages(struct pglist_data *pgdat,
4247                 unsigned long *zones_size, unsigned long *zholes_size)
4248 {
4249         unsigned long realtotalpages, totalpages = 0;
4250         enum zone_type i;
4251 
4252         for (i = 0; i < MAX_NR_ZONES; i++)
4253                 totalpages += zone_spanned_pages_in_node(pgdat->node_id, i,
4254                                                                 zones_size);
4255         pgdat->node_spanned_pages = totalpages;
4256 
4257         realtotalpages = totalpages;
4258         for (i = 0; i < MAX_NR_ZONES; i++)
4259                 realtotalpages -=
4260                         zone_absent_pages_in_node(pgdat->node_id, i,
4261                                                                 zholes_size);
4262         pgdat->node_present_pages = realtotalpages;
4263         printk(KERN_DEBUG "On node %d totalpages: %lu\n", pgdat->node_id,
4264                                                         realtotalpages);
4265 }
4266 
4267 #ifndef CONFIG_SPARSEMEM
4268 /*
4269  * Calculate the size of the zone->blockflags rounded to an unsigned long
4270  * Start by making sure zonesize is a multiple of pageblock_order by rounding
4271  * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
4272  * round what is now in bits to nearest long in bits, then return it in
4273  * bytes.
4274  */
4275 static unsigned long __init usemap_size(unsigned long zonesize)
4276 {
4277         unsigned long usemapsize;
4278 
4279         usemapsize = roundup(zonesize, pageblock_nr_pages);
4280         usemapsize = usemapsize >> pageblock_order;
4281         usemapsize *= NR_PAGEBLOCK_BITS;
4282         usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
4283 
4284         return usemapsize / 8;
4285 }
4286 
4287 static void __init setup_usemap(struct pglist_data *pgdat,
4288                                 struct zone *zone, unsigned long zonesize)
4289 {
4290         unsigned long usemapsize = usemap_size(zonesize);
4291         zone->pageblock_flags = NULL;
4292         if (usemapsize)
4293                 zone->pageblock_flags = alloc_bootmem_node_nopanic(pgdat,
4294                                                                    usemapsize);
4295 }
4296 #else
4297 static inline void setup_usemap(struct pglist_data *pgdat,
4298                                 struct zone *zone, unsigned long zonesize) {}
4299 #endif /* CONFIG_SPARSEMEM */
4300 
4301 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
4302 
4303 /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
4304 void __init set_pageblock_order(void)
4305 {
4306         unsigned int order;
4307 
4308         /* Check that pageblock_nr_pages has not already been setup */
4309         if (pageblock_order)
4310                 return;
4311 
4312         if (HPAGE_SHIFT > PAGE_SHIFT)
4313                 order = HUGETLB_PAGE_ORDER;
4314         else
4315                 order = MAX_ORDER - 1;
4316 
4317         /*
4318          * Assume the largest contiguous order of interest is a huge page.
4319          * This value may be variable depending on boot parameters on IA64 and
4320          * powerpc.
4321          */
4322         pageblock_order = order;
4323 }
4324 #else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
4325 
4326 /*
4327  * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
4328  * is unused as pageblock_order is set at compile-time. See
4329  * include/linux/pageblock-flags.h for the values of pageblock_order based on
4330  * the kernel config
4331  */
4332 void __init set_pageblock_order(void)
4333 {
4334 }
4335 
4336 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
4337 
4338 /*
4339  * Set up the zone data structures:
4340  *   - mark all pages reserved
4341  *   - mark all memory queues empty
4342  *   - clear the memory bitmaps
4343  */
4344 static void __paginginit free_area_init_core(struct pglist_data *pgdat,
4345                 unsigned long *zones_size, unsigned long *zholes_size)
4346 {
4347         enum zone_type j;
4348         int nid = pgdat->node_id;
4349         unsigned long zone_start_pfn = pgdat->node_start_pfn;
4350         int ret;
4351 
4352         pgdat_resize_init(pgdat);
4353         pgdat->nr_zones = 0;
4354         init_waitqueue_head(&pgdat->kswapd_wait);
4355         pgdat->kswapd_max_order = 0;
4356         pgdat_page_cgroup_init(pgdat);
4357 
4358         for (j = 0; j < MAX_NR_ZONES; j++) {
4359                 struct zone *zone = pgdat->node_zones + j;
4360                 unsigned long size, realsize, memmap_pages;
4361 
4362                 size = zone_spanned_pages_in_node(nid, j, zones_size);
4363                 realsize = size - zone_absent_pages_in_node(nid, j,
4364                                                                 zholes_size);
4365 
4366                 /*
4367                  * Adjust realsize so that it accounts for how much memory
4368                  * is used by this zone for memmap. This affects the watermark
4369                  * and per-cpu initialisations
4370                  */
4371                 memmap_pages =
4372                         PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT;
4373                 if (realsize >= memmap_pages) {
4374                         realsize -= memmap_pages;
4375                         if (memmap_pages)
4376                                 printk(KERN_DEBUG
4377                                        "  %s zone: %lu pages used for memmap\n",
4378                                        zone_names[j], memmap_pages);
4379                 } else
4380                         printk(KERN_WARNING
4381                                 "  %s zone: %lu pages exceeds realsize %lu\n",
4382                                 zone_names[j], memmap_pages, realsize);
4383 
4384                 /* Account for reserved pages */
4385                 if (j == 0 && realsize > dma_reserve) {
4386                         realsize -= dma_reserve;
4387                         printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
4388                                         zone_names[0], dma_reserve);
4389                 }
4390 
4391                 if (!is_highmem_idx(j))
4392                         nr_kernel_pages += realsize;
4393                 nr_all_pages += realsize;
4394 
4395                 zone->spanned_pages = size;
4396                 zone->present_pages = realsize;
4397 #ifdef CONFIG_NUMA
4398                 zone->node = nid;
4399                 zone->min_unmapped_pages = (realsize*sysctl_min_unmapped_ratio)
4400                                                 / 100;
4401                 zone->min_slab_pages = (realsize * sysctl_min_slab_ratio) / 100;
4402 #endif
4403                 zone->name = zone_names[j];
4404                 spin_lock_init(&zone->lock);
4405                 spin_lock_init(&zone->lru_lock);
4406                 zone_seqlock_init(zone);
4407                 zone->zone_pgdat = pgdat;
4408 
4409                 zone_pcp_init(zone);
4410                 lruvec_init(&zone->lruvec, zone);
4411                 zap_zone_vm_stats(zone);
4412                 zone->flags = 0;
4413                 if (!size)
4414                         continue;
4415 
4416                 set_pageblock_order();
4417                 setup_usemap(pgdat, zone, size);
4418                 ret = init_currently_empty_zone(zone, zone_start_pfn,
4419                                                 size, MEMMAP_EARLY);
4420                 BUG_ON(ret);
4421                 memmap_init(size, nid, j, zone_start_pfn);
4422                 zone_start_pfn += size;
4423         }
4424 }
4425 
4426 static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
4427 {
4428         /* Skip empty nodes */
4429         if (!pgdat->node_spanned_pages)
4430                 return;
4431 
4432 #ifdef CONFIG_FLAT_NODE_MEM_MAP
4433         /* ia64 gets its own node_mem_map, before this, without bootmem */
4434         if (!pgdat->node_mem_map) {
4435                 unsigned long size, start, end;
4436                 struct page *map;
4437 
4438                 /*
4439                  * The zone's endpoints aren't required to be MAX_ORDER
4440                  * aligned but the node_mem_map endpoints must be in order
4441                  * for the buddy allocator to function correctly.
4442                  */
4443                 start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
4444                 end = pgdat->node_start_pfn + pgdat->node_spanned_pages;
4445                 end = ALIGN(end, MAX_ORDER_NR_PAGES);
4446                 size =  (end - start) * sizeof(struct page);
4447                 map = alloc_remap(pgdat->node_id, size);
4448                 if (!map)
4449                         map = alloc_bootmem_node_nopanic(pgdat, size);
4450                 pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
4451         }
4452 #ifndef CONFIG_NEED_MULTIPLE_NODES
4453         /*
4454          * With no DISCONTIG, the global mem_map is just set as node 0's
4455          */
4456         if (pgdat == NODE_DATA(0)) {
4457                 mem_map = NODE_DATA(0)->node_mem_map;
4458 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
4459                 if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
4460                         mem_map -= (pgdat->node_start_pfn - ARCH_PFN_OFFSET);
4461 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
4462         }
4463 #endif
4464 #endif /* CONFIG_FLAT_NODE_MEM_MAP */
4465 }
4466 
4467 void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
4468                 unsigned long node_start_pfn, unsigned long *zholes_size)
4469 {
4470         pg_data_t *pgdat = NODE_DATA(nid);
4471 
4472         pgdat->node_id = nid;
4473         pgdat->node_start_pfn = node_start_pfn;
4474         calculate_node_totalpages(pgdat, zones_size, zholes_size);
4475 
4476         alloc_node_mem_map(pgdat);
4477 #ifdef CONFIG_FLAT_NODE_MEM_MAP
4478         printk(KERN_DEBUG "free_area_init_node: node %d, pgdat %08lx, node_mem_map %08lx\n",
4479                 nid, (unsigned long)pgdat,
4480                 (unsigned long)pgdat->node_mem_map);
4481 #endif
4482 
4483         free_area_init_core(pgdat, zones_size, zholes_size);
4484 }
4485 
4486 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
4487 
4488 #if MAX_NUMNODES > 1
4489 /*
4490  * Figure out the number of possible node ids.
4491  */
4492 static void __init setup_nr_node_ids(void)
4493 {
4494         unsigned int node;
4495         unsigned int highest = 0;
4496 
4497         for_each_node_mask(node, node_possible_map)
4498                 highest = node;
4499         nr_node_ids = highest + 1;
4500 }
4501 #else
4502 static inline void setup_nr_node_ids(void)
4503 {
4504 }
4505 #endif
4506 
4507 /**
4508  * node_map_pfn_alignment - determine the maximum internode alignment
4509  *
4510  * This function should be called after node map is populated and sorted.
4511  * It calculates the maximum power of two alignment which can distinguish
4512  * all the nodes.
4513  *
4514  * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
4515  * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
4516  * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
4517  * shifted, 1GiB is enough and this function will indicate so.
4518  *
4519  * This is used to test whether pfn -> nid mapping of the chosen memory
4520  * model has fine enough granularity to avoid incorrect mapping for the
4521  * populated node map.
4522  *
4523  * Returns the determined alignment in pfn's.  0 if there is no alignment
4524  * requirement (single node).
4525  */
4526 unsigned long __init node_map_pfn_alignment(void)
4527 {
4528         unsigned long accl_mask = 0, last_end = 0;
4529         unsigned long start, end, mask;
4530         int last_nid = -1;
4531         int i, nid;
4532 
4533         for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
4534                 if (!start || last_nid < 0 || last_nid == nid) {
4535                         last_nid = nid;
4536                         last_end = end;
4537                         continue;
4538                 }
4539 
4540                 /*
4541                  * Start with a mask granular enough to pin-point to the
4542                  * start pfn and tick off bits one-by-one until it becomes
4543                  * too coarse to separate the current node from the last.
4544                  */
4545                 mask = ~((1 << __ffs(start)) - 1);
4546                 while (mask && last_end <= (start & (mask << 1)))
4547                         mask <<= 1;
4548 
4549                 /* accumulate all internode masks */
4550                 accl_mask |= mask;
4551         }
4552 
4553         /* convert mask to number of pages */
4554         return ~accl_mask + 1;
4555 }
4556 
4557 /* Find the lowest pfn for a node */
4558 static unsigned long __init find_min_pfn_for_node(int nid)
4559 {
4560         unsigned long min_pfn = ULONG_MAX;
4561         unsigned long start_pfn;
4562         int i;
4563 
4564         for_each_mem_pfn_range(i, nid, &start_pfn, NULL, NULL)
4565                 min_pfn = min(min_pfn, start_pfn);
4566 
4567         if (min_pfn == ULONG_MAX) {
4568                 printk(KERN_WARNING
4569                         "Could not find start_pfn for node %d\n", nid);
4570                 return 0;
4571         }
4572 
4573         return min_pfn;
4574 }
4575 
4576 /**
4577  * find_min_pfn_with_active_regions - Find the minimum PFN registered
4578  *
4579  * It returns the minimum PFN based on information provided via
4580  * add_active_range().
4581  */
4582 unsigned long __init find_min_pfn_with_active_regions(void)
4583 {
4584         return find_min_pfn_for_node(MAX_NUMNODES);
4585 }
4586 
4587 /*
4588  * early_calculate_totalpages()
4589  * Sum pages in active regions for movable zone.
4590  * Populate N_HIGH_MEMORY for calculating usable_nodes.
4591  */
4592 static unsigned long __init early_calculate_totalpages(void)
4593 {
4594         unsigned long totalpages = 0;
4595         unsigned long start_pfn, end_pfn;
4596         int i, nid;
4597 
4598         for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
4599                 unsigned long pages = end_pfn - start_pfn;
4600 
4601                 totalpages += pages;
4602                 if (pages)
4603                         node_set_state(nid, N_HIGH_MEMORY);
4604         }
4605         return totalpages;
4606 }
4607 
4608 /*
4609  * Find the PFN the Movable zone begins in each node. Kernel memory
4610  * is spread evenly between nodes as long as the nodes have enough
4611  * memory. When they don't, some nodes will have more kernelcore than
4612  * others
4613  */
4614 static void __init find_zone_movable_pfns_for_nodes(void)
4615 {
4616         int i, nid;
4617         unsigned long usable_startpfn;
4618         unsigned long kernelcore_node, kernelcore_remaining;
4619         /* save the state before borrow the nodemask */
4620         nodemask_t saved_node_state = node_states[N_HIGH_MEMORY];
4621         unsigned long totalpages = early_calculate_totalpages();
4622         int usable_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
4623 
4624         /*
4625          * If movablecore was specified, calculate what size of
4626          * kernelcore that corresponds so that memory usable for
4627          * any allocation type is evenly spread. If both kernelcore
4628          * and movablecore are specified, then the value of kernelcore
4629          * will be used for required_kernelcore if it's greater than
4630          * what movablecore would have allowed.
4631          */
4632         if (required_movablecore) {
4633                 unsigned long corepages;
4634 
4635                 /*
4636                  * Round-up so that ZONE_MOVABLE is at least as large as what
4637                  * was requested by the user
4638                  */
4639                 required_movablecore =
4640                         roundup(required_movablecore, MAX_ORDER_NR_PAGES);
4641                 corepages = totalpages - required_movablecore;
4642 
4643                 required_kernelcore = max(required_kernelcore, corepages);
4644         }
4645 
4646         /* If kernelcore was not specified, there is no ZONE_MOVABLE */
4647         if (!required_kernelcore)
4648                 goto out;
4649 
4650         /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
4651         find_usable_zone_for_movable();
4652         usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
4653 
4654 restart:
4655         /* Spread kernelcore memory as evenly as possible throughout nodes */
4656         kernelcore_node = required_kernelcore / usable_nodes;
4657         for_each_node_state(nid, N_HIGH_MEMORY) {
4658                 unsigned long start_pfn, end_pfn;
4659 
4660                 /*
4661                  * Recalculate kernelcore_node if the division per node
4662                  * now exceeds what is necessary to satisfy the requested
4663                  * amount of memory for the kernel
4664                  */
4665                 if (required_kernelcore < kernelcore_node)
4666                         kernelcore_node = required_kernelcore / usable_nodes;
4667 
4668                 /*
4669                  * As the map is walked, we track how much memory is usable
4670                  * by the kernel using kernelcore_remaining. When it is
4671                  * 0, the rest of the node is usable by ZONE_MOVABLE
4672                  */
4673                 kernelcore_remaining = kernelcore_node;
4674 
4675                 /* Go through each range of PFNs within this node */
4676                 for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
4677                         unsigned long size_pages;
4678 
4679                         start_pfn = max(start_pfn, zone_movable_pfn[nid]);
4680                         if (start_pfn >= end_pfn)
4681                                 continue;
4682 
4683                         /* Account for what is only usable for kernelcore */
4684                         if (start_pfn < usable_startpfn) {
4685                                 unsigned long kernel_pages;
4686                                 kernel_pages = min(end_pfn, usable_startpfn)
4687                                                                 - start_pfn;
4688 
4689                                 kernelcore_remaining -= min(kernel_pages,
4690                                                         kernelcore_remaining);
4691                                 required_kernelcore -= min(kernel_pages,
4692                                                         required_kernelcore);
4693 
4694                                 /* Continue if range is now fully accounted */
4695                                 if (end_pfn <= usable_startpfn) {
4696 
4697                                         /*
4698                                          * Push zone_movable_pfn to the end so
4699                                          * that if we have to rebalance
4700                                          * kernelcore across nodes, we will
4701                                          * not double account here
4702                                          */
4703                                         zone_movable_pfn[nid] = end_pfn;
4704                                         continue;
4705                                 }
4706                                 start_pfn = usable_startpfn;
4707                         }
4708 
4709                         /*
4710                          * The usable PFN range for ZONE_MOVABLE is from
4711                          * start_pfn->end_pfn. Calculate size_pages as the
4712                          * number of pages used as kernelcore
4713                          */
4714                         size_pages = end_pfn - start_pfn;
4715                         if (size_pages > kernelcore_remaining)
4716                                 size_pages = kernelcore_remaining;
4717                         zone_movable_pfn[nid] = start_pfn + size_pages;
4718 
4719                         /*
4720                          * Some kernelcore has been met, update counts and
4721                          * break if the kernelcore for this node has been
4722                          * satisified
4723                          */
4724                         required_kernelcore -= min(required_kernelcore,
4725                                                                 size_pages);
4726                         kernelcore_remaining -= size_pages;
4727                         if (!kernelcore_remaining)
4728                                 break;
4729                 }
4730         }
4731 
4732         /*
4733          * If there is still required_kernelcore, we do another pass with one
4734          * less node in the count. This will push zone_movable_pfn[nid] further
4735          * along on the nodes that still have memory until kernelcore is
4736          * satisified
4737          */
4738         usable_nodes--;
4739         if (usable_nodes && required_kernelcore > usable_nodes)
4740                 goto restart;
4741 
4742         /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
4743         for (nid = 0; nid < MAX_NUMNODES; nid++)
4744                 zone_movable_pfn[nid] =
4745                         roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
4746 
4747 out:
4748         /* restore the node_state */
4749         node_states[N_HIGH_MEMORY] = saved_node_state;
4750 }
4751 
4752 /* Any regular memory on that node ? */
4753 static void check_for_regular_memory(pg_data_t *pgdat)
4754 {
4755 #ifdef CONFIG_HIGHMEM
4756         enum zone_type zone_type;
4757 
4758         for (zone_type = 0; zone_type <= ZONE_NORMAL; zone_type++) {
4759                 struct zone *zone = &pgdat->node_zones[zone_type];
4760                 if (zone->present_pages) {
4761                         node_set_state(zone_to_nid(zone), N_NORMAL_MEMORY);
4762                         break;
4763                 }
4764         }
4765 #endif
4766 }
4767 
4768 /**
4769  * free_area_init_nodes - Initialise all pg_data_t and zone data
4770  * @max_zone_pfn: an array of max PFNs for each zone
4771  *
4772  * This will call free_area_init_node() for each active node in the system.
4773  * Using the page ranges provided by add_active_range(), the size of each
4774  * zone in each node and their holes is calculated. If the maximum PFN
4775  * between two adjacent zones match, it is assumed that the zone is empty.
4776  * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
4777  * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
4778  * starts where the previous one ended. For example, ZONE_DMA32 starts
4779  * at arch_max_dma_pfn.
4780  */
4781 void __init free_area_init_nodes(unsigned long *max_zone_pfn)
4782 {
4783         unsigned long start_pfn, end_pfn;
4784         int i, nid;
4785 
4786         /* Record where the zone boundaries are */
4787         memset(arch_zone_lowest_possible_pfn, 0,
4788                                 sizeof(arch_zone_lowest_possible_pfn));
4789         memset(arch_zone_highest_possible_pfn, 0,
4790                                 sizeof(arch_zone_highest_possible_pfn));
4791         arch_zone_lowest_possible_pfn[0] = find_min_pfn_with_active_regions();
4792         arch_zone_highest_possible_pfn[0] = max_zone_pfn[0];
4793         for (i = 1; i < MAX_NR_ZONES; i++) {
4794                 if (i == ZONE_MOVABLE)
4795                         continue;
4796                 arch_zone_lowest_possible_pfn[i] =
4797                         arch_zone_highest_possible_pfn[i-1];
4798                 arch_zone_highest_possible_pfn[i] =
4799                         max(max_zone_pfn[i], arch_zone_lowest_possible_pfn[i]);
4800         }
4801         arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;
4802         arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;
4803 
4804         /* Find the PFNs that ZONE_MOVABLE begins at in each node */
4805         memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
4806         find_zone_movable_pfns_for_nodes();
4807 
4808         /* Print out the zone ranges */
4809         printk("Zone ranges:\n");
4810         for (i = 0; i < MAX_NR_ZONES; i++) {
4811                 if (i == ZONE_MOVABLE)
4812                         continue;
4813                 printk(KERN_CONT "  %-8s ", zone_names[i]);
4814                 if (arch_zone_lowest_possible_pfn[i] ==
4815                                 arch_zone_highest_possible_pfn[i])
4816                         printk(KERN_CONT "empty\n");
4817                 else
4818                         printk(KERN_CONT "[mem %0#10lx-%0#10lx]\n",
4819                                 arch_zone_lowest_possible_pfn[i] << PAGE_SHIFT,
4820                                 (arch_zone_highest_possible_pfn[i]
4821                                         << PAGE_SHIFT) - 1);
4822         }
4823 
4824         /* Print out the PFNs ZONE_MOVABLE begins at in each node */
4825         printk("Movable zone start for each node\n");
4826         for (i = 0; i < MAX_NUMNODES; i++) {
4827                 if (zone_movable_pfn[i])
4828                         printk("  Node %d: %#010lx\n", i,
4829                                zone_movable_pfn[i] << PAGE_SHIFT);
4830         }
4831 
4832         /* Print out the early_node_map[] */
4833         printk("Early memory node ranges\n");
4834         for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
4835                 printk("  node %3d: [mem %#010lx-%#010lx]\n", nid,
4836                        start_pfn << PAGE_SHIFT, (end_pfn << PAGE_SHIFT) - 1);
4837 
4838         /* Initialise every node */
4839         mminit_verify_pageflags_layout();
4840         setup_nr_node_ids();
4841         for_each_online_node(nid) {
4842                 pg_data_t *pgdat = NODE_DATA(nid);
4843                 free_area_init_node(nid, NULL,
4844                                 find_min_pfn_for_node(nid), NULL);
4845 
4846                 /* Any memory on that node */
4847                 if (pgdat->node_present_pages)
4848                         node_set_state(nid, N_HIGH_MEMORY);
4849                 check_for_regular_memory(pgdat);
4850         }
4851 }
4852 
4853 static int __init cmdline_parse_core(char *p, unsigned long *core)
4854 {
4855         unsigned long long coremem;
4856         if (!p)
4857                 return -EINVAL;
4858 
4859         coremem = memparse(p, &p);
4860         *core = coremem >> PAGE_SHIFT;
4861 
4862         /* Paranoid check that UL is enough for the coremem value */
4863         WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);
4864 
4865         return 0;
4866 }
4867 
4868 /*
4869  * kernelcore=size sets the amount of memory for use for allocations that
4870  * cannot be reclaimed or migrated.
4871  */
4872 static int __init cmdline_parse_kernelcore(char *p)
4873 {
4874         return cmdline_parse_core(p, &required_kernelcore);
4875 }
4876 
4877 /*
4878  * movablecore=size sets the amount of memory for use for allocations that
4879  * can be reclaimed or migrated.
4880  */
4881 static int __init cmdline_parse_movablecore(char *p)
4882 {
4883         return cmdline_parse_core(p, &required_movablecore);
4884 }
4885 
4886 early_param("kernelcore", cmdline_parse_kernelcore);
4887 early_param("movablecore", cmdline_parse_movablecore);
4888 
4889 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
4890 
4891 /**
4892  * set_dma_reserve - set the specified number of pages reserved in the first zone
4893  * @new_dma_reserve: The number of pages to mark reserved
4894  *
4895  * The per-cpu batchsize and zone watermarks are determined by present_pages.
4896  * In the DMA zone, a significant percentage may be consumed by kernel image
4897  * and other unfreeable allocations which can skew the watermarks badly. This
4898  * function may optionally be used to account for unfreeable pages in the
4899  * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
4900  * smaller per-cpu batchsize.
4901  */
4902 void __init set_dma_reserve(unsigned long new_dma_reserve)
4903 {
4904         dma_reserve = new_dma_reserve;
4905 }
4906 
4907 void __init free_area_init(unsigned long *zones_size)
4908 {
4909         free_area_init_node(0, zones_size,
4910                         __pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
4911 }
4912 
4913 static int page_alloc_cpu_notify(struct notifier_block *self,
4914                                  unsigned long action, void *hcpu)
4915 {
4916         int cpu = (unsigned long)hcpu;
4917 
4918         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
4919                 lru_add_drain_cpu(cpu);
4920                 drain_pages(cpu);
4921 
4922                 /*
4923                  * Spill the event counters of the dead processor
4924                  * into the current processors event counters.
4925                  * This artificially elevates the count of the current
4926                  * processor.
4927                  */
4928                 vm_events_fold_cpu(cpu);
4929 
4930                 /*
4931                  * Zero the differential counters of the dead processor
4932                  * so that the vm statistics are consistent.
4933                  *
4934                  * This is only okay since the processor is dead and cannot
4935                  * race with what we are doing.
4936                  */
4937                 refresh_cpu_vm_stats(cpu);
4938         }
4939         return NOTIFY_OK;
4940 }
4941 
4942 void __init page_alloc_init(void)
4943 {
4944         hotcpu_notifier(page_alloc_cpu_notify, 0);
4945 }
4946 
4947 /*
4948  * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
4949  *      or min_free_kbytes changes.
4950  */
4951 static void calculate_totalreserve_pages(void)
4952 {
4953         struct pglist_data *pgdat;
4954         unsigned long reserve_pages = 0;
4955         enum zone_type i, j;
4956 
4957         for_each_online_pgdat(pgdat) {
4958                 for (i = 0; i < MAX_NR_ZONES; i++) {
4959                         struct zone *zone = pgdat->node_zones + i;
4960                         unsigned long max = 0;
4961 
4962                         /* Find valid and maximum lowmem_reserve in the zone */
4963                         for (j = i; j < MAX_NR_ZONES; j++) {
4964                                 if (zone->lowmem_reserve[j] > max)
4965                                         max = zone->lowmem_reserve[j];
4966                         }
4967 
4968                         /* we treat the high watermark as reserved pages. */
4969                         max += high_wmark_pages(zone);
4970 
4971                         if (max > zone->present_pages)
4972                                 max = zone->present_pages;
4973                         reserve_pages += max;
4974                         /*
4975                          * Lowmem reserves are not available to
4976                          * GFP_HIGHUSER page cache allocations and
4977                          * kswapd tries to balance zones to their high
4978                          * watermark.  As a result, neither should be
4979                          * regarded as dirtyable memory, to prevent a
4980                          * situation where reclaim has to clean pages
4981                          * in order to balance the zones.
4982                          */
4983                         zone->dirty_balance_reserve = max;
4984                 }
4985         }
4986         dirty_balance_reserve = reserve_pages;
4987         totalreserve_pages = reserve_pages;
4988 }
4989 
4990 /*
4991  * setup_per_zone_lowmem_reserve - called whenever
4992  *      sysctl_lower_zone_reserve_ratio changes.  Ensures that each zone
4993  *      has a correct pages reserved value, so an adequate number of
4994  *      pages are left in the zone after a successful __alloc_pages().
4995  */
4996 static void setup_per_zone_lowmem_reserve(void)
4997 {
4998         struct pglist_data *pgdat;
4999         enum zone_type j, idx;
5000 
5001         for_each_online_pgdat(pgdat) {
5002                 for (j = 0; j < MAX_NR_ZONES; j++) {
5003                         struct zone *zone = pgdat->node_zones + j;
5004                         unsigned long present_pages = zone->present_pages;
5005 
5006                         zone->lowmem_reserve[j] = 0;
5007 
5008                         idx = j;
5009                         while (idx) {
5010                                 struct zone *lower_zone;
5011 
5012                                 idx--;
5013 
5014                                 if (sysctl_lowmem_reserve_ratio[idx] < 1)
5015                                         sysctl_lowmem_reserve_ratio[idx] = 1;
5016 
5017                                 lower_zone = pgdat->node_zones + idx;
5018                                 lower_zone->lowmem_reserve[j] = present_pages /
5019                                         sysctl_lowmem_reserve_ratio[idx];
5020                                 present_pages += lower_zone->present_pages;
5021                         }
5022                 }
5023         }
5024 
5025         /* update totalreserve_pages */
5026         calculate_totalreserve_pages();
5027 }
5028 
5029 static void __setup_per_zone_wmarks(void)
5030 {
5031         unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
5032         unsigned long lowmem_pages = 0;
5033         struct zone *zone;
5034         unsigned long flags;
5035 
5036         /* Calculate total number of !ZONE_HIGHMEM pages */
5037         for_each_zone(zone) {
5038                 if (!is_highmem(zone))
5039                         lowmem_pages += zone->present_pages;
5040         }
5041 
5042         for_each_zone(zone) {
5043                 u64 tmp;
5044 
5045                 spin_lock_irqsave(&zone->lock, flags);
5046                 tmp = (u64)pages_min * zone->present_pages;
5047                 do_div(tmp, lowmem_pages);
5048                 if (is_highmem(zone)) {
5049                         /*
5050                          * __GFP_HIGH and PF_MEMALLOC allocations usually don't
5051                          * need highmem pages, so cap pages_min to a small
5052                          * value here.
5053                          *
5054                          * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
5055                          * deltas controls asynch page reclaim, and so should
5056                          * not be capped for highmem.
5057                          */
5058                         int min_pages;
5059 
5060                         min_pages = zone->present_pages / 1024;
5061                         if (min_pages < SWAP_CLUSTER_MAX)
5062                                 min_pages = SWAP_CLUSTER_MAX;
5063                         if (min_pages > 128)
5064                                 min_pages = 128;
5065                         zone->watermark[WMARK_MIN] = min_pages;
5066                 } else {
5067                         /*
5068                          * If it's a lowmem zone, reserve a number of pages
5069                          * proportionate to the zone's size.
5070                          */
5071                         zone->watermark[WMARK_MIN] = tmp;
5072                 }
5073 
5074                 zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) + (tmp >> 2);
5075                 zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1);
5076 
5077                 zone->watermark[WMARK_MIN] += cma_wmark_pages(zone);
5078                 zone->watermark[WMARK_LOW] += cma_wmark_pages(zone);
5079                 zone->watermark[WMARK_HIGH] += cma_wmark_pages(zone);
5080 
5081                 setup_zone_migrate_reserve(zone);
5082                 spin_unlock_irqrestore(&zone->lock, flags);
5083         }
5084 
5085         /* update totalreserve_pages */
5086         calculate_totalreserve_pages();
5087 }
5088 
5089 /**
5090  * setup_per_zone_wmarks - called when min_free_kbytes changes
5091  * or when memory is hot-{added|removed}
5092  *
5093  * Ensures that the watermark[min,low,high] values for each zone are set
5094  * correctly with respect to min_free_kbytes.
5095  */
5096 void setup_per_zone_wmarks(void)
5097 {
5098         mutex_lock(&zonelists_mutex);
5099         __setup_per_zone_wmarks();
5100         mutex_unlock(&zonelists_mutex);
5101 }
5102 
5103 /*
5104  * The inactive anon list should be small enough that the VM never has to
5105  * do too much work, but large enough that each inactive page has a chance
5106  * to be referenced again before it is swapped out.
5107  *
5108  * The inactive_anon ratio is the target ratio of ACTIVE_ANON to
5109  * INACTIVE_ANON pages on this zone's LRU, maintained by the
5110  * pageout code. A zone->inactive_ratio of 3 means 3:1 or 25% of
5111  * the anonymous pages are kept on the inactive list.
5112  *
5113  * total     target    max
5114  * memory    ratio     inactive anon
5115  * -------------------------------------
5116  *   10MB       1         5MB
5117  *  100MB       1        50MB
5118  *    1GB       3       250MB
5119  *   10GB      10       0.9GB
5120  *  100GB      31         3GB
5121  *    1TB     101        10GB
5122  *   10TB     320        32GB
5123  */
5124 static void __meminit calculate_zone_inactive_ratio(struct zone *zone)
5125 {
5126         unsigned int gb, ratio;
5127 
5128         /* Zone size in gigabytes */
5129         gb = zone->present_pages >> (30 - PAGE_SHIFT);
5130         if (gb)
5131                 ratio = int_sqrt(10 * gb);
5132         else
5133                 ratio = 1;
5134 
5135         zone->inactive_ratio = ratio;
5136 }
5137 
5138 static void __meminit setup_per_zone_inactive_ratio(void)
5139 {
5140         struct zone *zone;
5141 
5142         for_each_zone(zone)
5143                 calculate_zone_inactive_ratio(zone);
5144 }
5145 
5146 /*
5147  * Initialise min_free_kbytes.
5148  *
5149  * For small machines we want it small (128k min).  For large machines
5150  * we want it large (64MB max).  But it is not linear, because network
5151  * bandwidth does not increase linearly with machine size.  We use
5152  *
5153  *      min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
5154  *      min_free_kbytes = sqrt(lowmem_kbytes * 16)
5155  *
5156  * which yields
5157  *
5158  * 16MB:        512k
5159  * 32MB:        724k
5160  * 64MB:        1024k
5161  * 128MB:       1448k
5162  * 256MB:       2048k
5163  * 512MB:       2896k
5164  * 1024MB:      4096k
5165  * 2048MB:      5792k
5166  * 4096MB:      8192k
5167  * 8192MB:      11584k
5168  * 16384MB:     16384k
5169  */
5170 int __meminit init_per_zone_wmark_min(void)
5171 {
5172         unsigned long lowmem_kbytes;
5173 
5174         lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
5175 
5176         min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
5177         if (min_free_kbytes < 128)
5178                 min_free_kbytes = 128;
5179         if (min_free_kbytes > 65536)
5180                 min_free_kbytes = 65536;
5181         setup_per_zone_wmarks();
5182         refresh_zone_stat_thresholds();
5183         setup_per_zone_lowmem_reserve();
5184         setup_per_zone_inactive_ratio();
5185         return 0;
5186 }
5187 module_init(init_per_zone_wmark_min)
5188 
5189 /*
5190  * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so 
5191  *      that we can call two helper functions whenever min_free_kbytes
5192  *      changes.
5193  */
5194 int min_free_kbytes_sysctl_handler(ctl_table *table, int write, 
5195         void __user *buffer, size_t *length, loff_t *ppos)
5196 {
5197         proc_dointvec(table, write, buffer, length, ppos);
5198         if (write)
5199                 setup_per_zone_wmarks();
5200         return 0;
5201 }
5202 
5203 #ifdef CONFIG_NUMA
5204 int sysctl_min_unmapped_ratio_sysctl_handler(ctl_table *table, int write,
5205         void __user *buffer, size_t *length, loff_t *ppos)
5206 {
5207         struct zone *zone;
5208         int rc;
5209 
5210         rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
5211         if (rc)
5212                 return rc;
5213 
5214         for_each_zone(zone)
5215                 zone->min_unmapped_pages = (zone->present_pages *
5216                                 sysctl_min_unmapped_ratio) / 100;
5217         return 0;
5218 }
5219 
5220 int sysctl_min_slab_ratio_sysctl_handler(ctl_table *table, int write,
5221         void __user *buffer, size_t *length, loff_t *ppos)
5222 {
5223         struct zone *zone;
5224         int rc;
5225 
5226         rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
5227         if (rc)
5228                 return rc;
5229 
5230         for_each_zone(zone)
5231                 zone->min_slab_pages = (zone->present_pages *
5232                                 sysctl_min_slab_ratio) / 100;
5233         return 0;
5234 }
5235 #endif
5236 
5237 /*
5238  * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
5239  *      proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
5240  *      whenever sysctl_lowmem_reserve_ratio changes.
5241  *
5242  * The reserve ratio obviously has absolutely no relation with the
5243  * minimum watermarks. The lowmem reserve ratio can only make sense
5244  * if in function of the boot time zone sizes.
5245  */
5246 int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write,
5247         void __user *buffer, size_t *length, loff_t *ppos)
5248 {
5249         proc_dointvec_minmax(table, write, buffer, length, ppos);
5250         setup_per_zone_lowmem_reserve();
5251         return 0;
5252 }
5253 
5254 /*
5255  * percpu_pagelist_fraction - changes the pcp->high for each zone on each
5256  * cpu.  It is the fraction of total pages in each zone that a hot per cpu pagelist
5257  * can have before it gets flushed back to buddy allocator.
5258  */
5259 
5260 int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
5261         void __user *buffer, size_t *length, loff_t *ppos)
5262 {
5263         struct zone *zone;
5264         unsigned int cpu;
5265         int ret;
5266 
5267         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
5268         if (!write || (ret < 0))
5269                 return ret;
5270         for_each_populated_zone(zone) {
5271                 for_each_possible_cpu(cpu) {
5272                         unsigned long  high;
5273                         high = zone->present_pages / percpu_pagelist_fraction;
5274                         setup_pagelist_highmark(
5275                                 per_cpu_ptr(zone->pageset, cpu), high);
5276                 }
5277         }
5278         return 0;
5279 }
5280 
5281 int hashdist = HASHDIST_DEFAULT;
5282 
5283 #ifdef CONFIG_NUMA
5284 static int __init set_hashdist(char *str)
5285 {
5286         if (!str)
5287                 return 0;
5288         hashdist = simple_strtoul(str, &str, 0);
5289         return 1;
5290 }
5291 __setup("hashdist=", set_hashdist);
5292 #endif
5293 
5294 /*
5295  * allocate a large system hash table from bootmem
5296  * - it is assumed that the hash table must contain an exact power-of-2
5297  *   quantity of entries
5298  * - limit is the number of hash buckets, not the total allocation size
5299  */
5300 void *__init alloc_large_system_hash(const char *tablename,
5301                                      unsigned long bucketsize,
5302                                      unsigned long numentries,
5303                                      int scale,
5304                                      int flags,
5305                                      unsigned int *_hash_shift,
5306                                      unsigned int *_hash_mask,
5307                                      unsigned long low_limit,
5308                                      unsigned long high_limit)
5309 {
5310         unsigned long long max = high_limit;
5311         unsigned long log2qty, size;
5312         void *table = NULL;
5313 
5314         /* allow the kernel cmdline to have a say */
5315         if (!numentries) {
5316                 /* round applicable memory size up to nearest megabyte */
5317                 numentries = nr_kernel_pages;
5318                 numentries += (1UL << (20 - PAGE_SHIFT)) - 1;
5319                 numentries >>= 20 - PAGE_SHIFT;
5320                 numentries <<= 20 - PAGE_SHIFT;
5321 
5322                 /* limit to 1 bucket per 2^scale bytes of low memory */
5323                 if (scale > PAGE_SHIFT)
5324                         numentries >>= (scale - PAGE_SHIFT);
5325                 else
5326                         numentries <<= (PAGE_SHIFT - scale);
5327 
5328                 /* Make sure we've got at least a 0-order allocation.. */
5329                 if (unlikely(flags & HASH_SMALL)) {
5330                         /* Makes no sense without HASH_EARLY */
5331                         WARN_ON(!(flags & HASH_EARLY));
5332                         if (!(numentries >> *_hash_shift)) {
5333                                 numentries = 1UL << *_hash_shift;
5334                                 BUG_ON(!numentries);
5335                         }
5336                 } else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
5337                         numentries = PAGE_SIZE / bucketsize;
5338         }
5339         numentries = roundup_pow_of_two(numentries);
5340 
5341         /* limit allocation size to 1/16 total memory by default */
5342         if (max == 0) {
5343                 max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
5344                 do_div(max, bucketsize);
5345         }
5346         max = min(max, 0x80000000ULL);
5347 
5348         if (numentries < low_limit)
5349                 numentries = low_limit;
5350         if (numentries > max)
5351                 numentries = max;
5352 
5353         log2qty = ilog2(numentries);
5354 
5355         do {
5356                 size = bucketsize << log2qty;
5357                 if (flags & HASH_EARLY)
5358                         table = alloc_bootmem_nopanic(size);
5359                 else if (hashdist)
5360                         table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
5361                 else {
5362                         /*
5363                          * If bucketsize is not a power-of-two, we may free
5364                          * some pages at the end of hash table which
5365                          * alloc_pages_exact() automatically does
5366                          */
5367                         if (get_order(size) < MAX_ORDER) {
5368                                 table = alloc_pages_exact(size, GFP_ATOMIC);
5369                                 kmemleak_alloc(table, size, 1, GFP_ATOMIC);
5370                         }
5371                 }
5372         } while (!table && size > PAGE_SIZE && --log2qty);
5373 
5374         if (!table)
5375                 panic("Failed to allocate %s hash table\n", tablename);
5376 
5377         printk(KERN_INFO "%s hash table entries: %ld (order: %d, %lu bytes)\n",
5378                tablename,
5379                (1UL << log2qty),
5380                ilog2(size) - PAGE_SHIFT,
5381                size);
5382 
5383         if (_hash_shift)
5384                 *_hash_shift = log2qty;
5385         if (_hash_mask)
5386                 *_hash_mask = (1 << log2qty) - 1;
5387 
5388         return table;
5389 }
5390 
5391 /* Return a pointer to the bitmap storing bits affecting a block of pages */
5392 static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
5393                                                         unsigned long pfn)
5394 {
5395 #ifdef CONFIG_SPARSEMEM
5396         return __pfn_to_section(pfn)->pageblock_flags;
5397 #else
5398         return zone->pageblock_flags;
5399 #endif /* CONFIG_SPARSEMEM */
5400 }
5401 
5402 static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
5403 {
5404 #ifdef CONFIG_SPARSEMEM
5405         pfn &= (PAGES_PER_SECTION-1);
5406         return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
5407 #else
5408         pfn = pfn - zone->zone_start_pfn;
5409         return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
5410 #endif /* CONFIG_SPARSEMEM */
5411 }
5412 
5413 /**
5414  * get_pageblock_flags_group - Return the requested group of flags for the pageblock_nr_pages block of pages
5415  * @page: The page within the block of interest
5416  * @start_bitidx: The first bit of interest to retrieve
5417  * @end_bitidx: The last bit of interest
5418  * returns pageblock_bits flags
5419  */
5420 unsigned long get_pageblock_flags_group(struct page *page,
5421                                         int start_bitidx, int end_bitidx)
5422 {
5423         struct zone *zone;
5424         unsigned long *bitmap;
5425         unsigned long pfn, bitidx;
5426         unsigned long flags = 0;
5427         unsigned long value = 1;
5428 
5429         zone = page_zone(page);
5430         pfn = page_to_pfn(page);
5431         bitmap = get_pageblock_bitmap(zone, pfn);
5432         bitidx = pfn_to_bitidx(zone, pfn);
5433 
5434         for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
5435                 if (test_bit(bitidx + start_bitidx, bitmap))
5436                         flags |= value;
5437 
5438         return flags;
5439 }
5440 
5441 /**
5442  * set_pageblock_flags_group - Set the requested group of flags for a pageblock_nr_pages block of pages
5443  * @page: The page within the block of interest
5444  * @start_bitidx: The first bit of interest
5445  * @end_bitidx: The last bit of interest
5446  * @flags: The flags to set
5447  */
5448 void set_pageblock_flags_group(struct page *page, unsigned long flags,
5449                                         int start_bitidx, int end_bitidx)
5450 {
5451         struct zone *zone;
5452         unsigned long *bitmap;
5453         unsigned long pfn, bitidx;
5454         unsigned long value = 1;
5455 
5456         zone = page_zone(page);
5457         pfn = page_to_pfn(page);
5458         bitmap = get_pageblock_bitmap(zone, pfn);
5459         bitidx = pfn_to_bitidx(zone, pfn);
5460         VM_BUG_ON(pfn < zone->zone_start_pfn);
5461         VM_BUG_ON(pfn >= zone->zone_start_pfn + zone->spanned_pages);
5462 
5463         for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
5464                 if (flags & value)
5465                         __set_bit(bitidx + start_bitidx, bitmap);
5466                 else
5467                         __clear_bit(bitidx + start_bitidx, bitmap);
5468 }
5469 
5470 /*
5471  * This is designed as sub function...plz see page_isolation.c also.
5472  * set/clear page block's type to be ISOLATE.
5473  * page allocater never alloc memory from ISOLATE block.
5474  */
5475 
5476 static int
5477 __count_immobile_pages(struct zone *zone, struct page *page, int count)
5478 {
5479         unsigned long pfn, iter, found;
5480         int mt;
5481 
5482         /*
5483          * For avoiding noise data, lru_add_drain_all() should be called
5484          * If ZONE_MOVABLE, the zone never contains immobile pages
5485          */
5486         if (zone_idx(zone) == ZONE_MOVABLE)
5487                 return true;
5488         mt = get_pageblock_migratetype(page);
5489         if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
5490                 return true;
5491 
5492         pfn = page_to_pfn(page);
5493         for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
5494                 unsigned long check = pfn + iter;
5495 
5496                 if (!pfn_valid_within(check))
5497                         continue;
5498 
5499                 page = pfn_to_page(check);
5500                 if (!page_count(page)) {
5501                         if (PageBuddy(page))
5502                                 iter += (1 << page_order(page)) - 1;
5503                         continue;
5504                 }
5505                 if (!PageLRU(page))
5506                         found++;
5507                 /*
5508                  * If there are RECLAIMABLE pages, we need to check it.
5509                  * But now, memory offline itself doesn't call shrink_slab()
5510                  * and it still to be fixed.
5511                  */
5512                 /*
5513                  * If the page is not RAM, page_count()should be 0.
5514                  * we don't need more check. This is an _used_ not-movable page.
5515                  *
5516                  * The problematic thing here is PG_reserved pages. PG_reserved
5517                  * is set to both of a memory hole page and a _used_ kernel
5518                  * page at boot.
5519                  */
5520                 if (found > count)
5521                         return false;
5522         }
5523         return true;
5524 }
5525 
5526 bool is_pageblock_removable_nolock(struct page *page)
5527 {
5528         struct zone *zone;
5529         unsigned long pfn;
5530 
5531         /*
5532          * We have to be careful here because we are iterating over memory
5533          * sections which are not zone aware so we might end up outside of
5534          * the zone but still within the section.
5535          * We have to take care about the node as well. If the node is offline
5536          * its NODE_DATA will be NULL - see page_zone.
5537          */
5538         if (!node_online(page_to_nid(page)))
5539                 return false;
5540 
5541         zone = page_zone(page);
5542         pfn = page_to_pfn(page);
5543         if (zone->zone_start_pfn > pfn ||
5544                         zone->zone_start_pfn + zone->spanned_pages <= pfn)
5545                 return false;
5546 
5547         return __count_immobile_pages(zone, page, 0);
5548 }
5549 
5550 int set_migratetype_isolate(struct page *page)
5551 {
5552         struct zone *zone;
5553         unsigned long flags, pfn;
5554         struct memory_isolate_notify arg;
5555         int notifier_ret;
5556         int ret = -EBUSY;
5557 
5558         zone = page_zone(page);
5559 
5560         spin_lock_irqsave(&zone->lock, flags);
5561 
5562         pfn = page_to_pfn(page);
5563         arg.start_pfn = pfn;
5564         arg.nr_pages = pageblock_nr_pages;
5565         arg.pages_found = 0;
5566 
5567         /*
5568          * It may be possible to isolate a pageblock even if the
5569          * migratetype is not MIGRATE_MOVABLE. The memory isolation
5570          * notifier chain is used by balloon drivers to return the
5571          * number of pages in a range that are held by the balloon
5572          * driver to shrink memory. If all the pages are accounted for
5573          * by balloons, are free, or on the LRU, isolation can continue.
5574          * Later, for example, when memory hotplug notifier runs, these
5575          * pages reported as "can be isolated" should be isolated(freed)
5576          * by the balloon driver through the memory notifier chain.
5577          */
5578         notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
5579         notifier_ret = notifier_to_errno(notifier_ret);
5580         if (notifier_ret)
5581                 goto out;
5582         /*
5583          * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
5584          * We just check MOVABLE pages.
5585          */
5586         if (__count_immobile_pages(zone, page, arg.pages_found))
5587                 ret = 0;
5588 
5589         /*
5590          * immobile means "not-on-lru" paes. If immobile is larger than
5591          * removable-by-driver pages reported by notifier, we'll fail.
5592          */
5593 
5594 out:
5595         if (!ret) {
5596                 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
5597                 move_freepages_block(zone, page, MIGRATE_ISOLATE);
5598         }
5599 
5600         spin_unlock_irqrestore(&zone->lock, flags);
5601         if (!ret)
5602                 drain_all_pages();
5603         return ret;
5604 }
5605 
5606 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
5607 {
5608         struct zone *zone;
5609         unsigned long flags;
5610         zone = page_zone(page);
5611         spin_lock_irqsave(&zone->lock, flags);
5612         if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
5613                 goto out;
5614         set_pageblock_migratetype(page, migratetype);
5615         move_freepages_block(zone, page, migratetype);
5616 out:
5617         spin_unlock_irqrestore(&zone->lock, flags);
5618 }
5619 
5620 #ifdef CONFIG_CMA
5621 
5622 static unsigned long pfn_max_align_down(unsigned long pfn)
5623 {
5624         return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
5625                              pageblock_nr_pages) - 1);
5626 }
5627 
5628 static unsigned long pfn_max_align_up(unsigned long pfn)
5629 {
5630         return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES,
5631                                 pageblock_nr_pages));
5632 }
5633 
5634 static struct page *
5635 __alloc_contig_migrate_alloc(struct page *page, unsigned long private,
5636                              int **resultp)
5637 {
5638         gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
5639 
5640         if (PageHighMem(page))
5641                 gfp_mask |= __GFP_HIGHMEM;
5642 
5643         return alloc_page(gfp_mask);
5644 }
5645 
5646 /* [start, end) must belong to a single zone. */
5647 static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
5648 {
5649         /* This function is based on compact_zone() from compaction.c. */
5650 
5651         unsigned long pfn = start;
5652         unsigned int tries = 0;
5653         int ret = 0;
5654 
5655         struct compact_control cc = {
5656                 .nr_migratepages = 0,
5657                 .order = -1,
5658                 .zone = page_zone(pfn_to_page(start)),
5659                 .sync = true,
5660         };
5661         INIT_LIST_HEAD(&cc.migratepages);
5662 
5663         migrate_prep_local();
5664 
5665         while (pfn < end || !list_empty(&cc.migratepages)) {
5666                 if (fatal_signal_pending(current)) {
5667                         ret = -EINTR;
5668                         break;
5669                 }
5670 
5671                 if (list_empty(&cc.migratepages)) {
5672                         cc.nr_migratepages = 0;
5673                         pfn = isolate_migratepages_range(cc.zone, &cc,
5674                                                          pfn, end);
5675                         if (!pfn) {
5676                                 ret = -EINTR;
5677                                 break;
5678                         }
5679                         tries = 0;
5680                 } else if (++tries == 5) {
5681                         ret = ret < 0 ? ret : -EBUSY;
5682                         break;
5683                 }
5684 
5685                 ret = migrate_pages(&cc.migratepages,
5686                                     __alloc_contig_migrate_alloc,
5687                                     0, false, MIGRATE_SYNC);
5688         }
5689 
5690         putback_lru_pages(&cc.migratepages);
5691         return ret > 0 ? 0 : ret;
5692 }
5693 
5694 /*
5695  * Update zone's cma pages counter used for watermark level calculation.
5696  */
5697 static inline void __update_cma_watermarks(struct zone *zone, int count)
5698 {
5699         unsigned long flags;
5700         spin_lock_irqsave(&zone->lock, flags);
5701         zone->min_cma_pages += count;
5702         spin_unlock_irqrestore(&zone->lock, flags);
5703         setup_per_zone_wmarks();
5704 }
5705 
5706 /*
5707  * Trigger memory pressure bump to reclaim some pages in order to be able to
5708  * allocate 'count' pages in single page units. Does similar work as
5709  *__alloc_pages_slowpath() function.
5710  */
5711 static int __reclaim_pages(struct zone *zone, gfp_t gfp_mask, int count)
5712 {
5713         enum zone_type high_zoneidx = gfp_zone(gfp_mask);
5714         struct zonelist *zonelist = node_zonelist(0, gfp_mask);
5715         int did_some_progress = 0;
5716         int order = 1;
5717 
5718         /*
5719          * Increase level of watermarks to force kswapd do his job
5720          * to stabilise at new watermark level.
5721          */
5722         __update_cma_watermarks(zone, count);
5723 
5724         /* Obey watermarks as if the page was being allocated */
5725         while (!zone_watermark_ok(zone, 0, low_wmark_pages(zone), 0, 0)) {
5726                 wake_all_kswapd(order, zonelist, high_zoneidx, zone_idx(zone));
5727 
5728                 did_some_progress = __perform_reclaim(gfp_mask, order, zonelist,
5729                                                       NULL);
5730                 if (!did_some_progress) {
5731                         /* Exhausted what can be done so it's blamo time */
5732                         out_of_memory(zonelist, gfp_mask, order, NULL, false);
5733                 }
5734         }
5735 
5736         /* Restore original watermark levels. */
5737         __update_cma_watermarks(zone, -count);
5738 
5739         return count;
5740 }
5741 
5742 /**
5743  * alloc_contig_range() -- tries to allocate given range of pages
5744  * @start:      start PFN to allocate
5745  * @end:        one-past-the-last PFN to allocate
5746  * @migratetype:        migratetype of the underlaying pageblocks (either
5747  *                      #MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
5748  *                      in range must have the same migratetype and it must
5749  *                      be either of the two.
5750  *
5751  * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
5752  * aligned, however it's the caller's responsibility to guarantee that
5753  * we are the only thread that changes migrate type of pageblocks the
5754  * pages fall in.
5755  *
5756  * The PFN range must belong to a single zone.
5757  *
5758  * Returns zero on success or negative error code.  On success all
5759  * pages which PFN is in [start, end) are allocated for the caller and
5760  * need to be freed with free_contig_range().
5761  */
5762 int alloc_contig_range(unsigned long start, unsigned long end,
5763                        unsigned migratetype)
5764 {
5765         struct zone *zone = page_zone(pfn_to_page(start));
5766         unsigned long outer_start, outer_end;
5767         int ret = 0, order;
5768 
5769         /*
5770          * What we do here is we mark all pageblocks in range as
5771          * MIGRATE_ISOLATE.  Because pageblock and max order pages may
5772          * have different sizes, and due to the way page allocator
5773          * work, we align the range to biggest of the two pages so
5774          * that page allocator won't try to merge buddies from
5775          * different pageblocks and change MIGRATE_ISOLATE to some
5776          * other migration type.
5777          *
5778          * Once the pageblocks are marked as MIGRATE_ISOLATE, we
5779          * migrate the pages from an unaligned range (ie. pages that
5780          * we are interested in).  This will put all the pages in
5781          * range back to page allocator as MIGRATE_ISOLATE.
5782          *
5783          * When this is done, we take the pages in range from page
5784          * allocator removing them from the buddy system.  This way
5785          * page allocator will never consider using them.
5786          *
5787          * This lets us mark the pageblocks back as
5788          * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
5789          * aligned range but not in the unaligned, original range are
5790          * put back to page allocator so that buddy can use them.
5791          */
5792 
5793         ret = start_isolate_page_range(pfn_max_align_down(start),
5794                                        pfn_max_align_up(end), migratetype);
5795         if (ret)
5796                 goto done;
5797 
5798         ret = __alloc_contig_migrate_range(start, end);
5799         if (ret)
5800                 goto done;
5801 
5802         /*
5803          * Pages from [start, end) are within a MAX_ORDER_NR_PAGES
5804          * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
5805          * more, all pages in [start, end) are free in page allocator.
5806          * What we are going to do is to allocate all pages from
5807          * [start, end) (that is remove them from page allocator).
5808          *
5809          * The only problem is that pages at the beginning and at the
5810          * end of interesting range may be not aligned with pages that
5811          * page allocator holds, ie. they can be part of higher order
5812          * pages.  Because of this, we reserve the bigger range and
5813          * once this is done free the pages we are not interested in.
5814          *
5815          * We don't have to hold zone->lock here because the pages are
5816          * isolated thus they won't get removed from buddy.
5817          */
5818 
5819         lru_add_drain_all();
5820         drain_all_pages();
5821 
5822         order = 0;
5823         outer_start = start;
5824         while (!PageBuddy(pfn_to_page(outer_start))) {
5825                 if (++order >= MAX_ORDER) {
5826                         ret = -EBUSY;
5827                         goto done;
5828                 }
5829                 outer_start &= ~0UL << order;
5830         }
5831 
5832         /* Make sure the range is really isolated. */
5833         if (test_pages_isolated(outer_start, end)) {
5834                 pr_warn("alloc_contig_range test_pages_isolated(%lx, %lx) failed\n",
5835                        outer_start, end);
5836                 ret = -EBUSY;
5837                 goto done;
5838         }
5839 
5840         /*
5841          * Reclaim enough pages to make sure that contiguous allocation
5842          * will not starve the system.
5843          */
5844         __reclaim_pages(zone, GFP_HIGHUSER_MOVABLE, end-start);
5845 
5846         /* Grab isolated pages from freelists. */
5847         outer_end = isolate_freepages_range(outer_start, end);
5848         if (!outer_end) {
5849                 ret = -EBUSY;
5850                 goto done;
5851         }
5852 
5853         /* Free head and tail (if any) */
5854         if (start != outer_start)
5855                 free_contig_range(outer_start, start - outer_start);
5856         if (end != outer_end)
5857                 free_contig_range(end, outer_end - end);
5858 
5859 done:
5860         undo_isolate_page_range(pfn_max_align_down(start),
5861                                 pfn_max_align_up(end), migratetype);
5862         return ret;
5863 }
5864 
5865 void free_contig_range(unsigned long pfn, unsigned nr_pages)
5866 {
5867         for (; nr_pages--; ++pfn)
5868                 __free_page(pfn_to_page(pfn));
5869 }
5870 #endif
5871 
5872 #ifdef CONFIG_MEMORY_HOTREMOVE
5873 /*
5874  * All pages in the range must be isolated before calling this.
5875  */
5876 void
5877 __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
5878 {
5879         struct page *page;
5880         struct zone *zone;
5881         int order, i;
5882         unsigned long pfn;
5883         unsigned long flags;
5884         /* find the first valid pfn */
5885         for (pfn = start_pfn; pfn < end_pfn; pfn++)
5886                 if (pfn_valid(pfn))
5887                         break;
5888         if (pfn == end_pfn)
5889                 return;
5890         zone = page_zone(pfn_to_page(pfn));
5891         spin_lock_irqsave(&zone->lock, flags);
5892         pfn = start_pfn;
5893         while (pfn < end_pfn) {
5894                 if (!pfn_valid(pfn)) {
5895                         pfn++;
5896                         continue;
5897                 }
5898                 page = pfn_to_page(pfn);
5899                 BUG_ON(page_count(page));
5900                 BUG_ON(!PageBuddy(page));
5901                 order = page_order(page);
5902 #ifdef CONFIG_DEBUG_VM
5903                 printk(KERN_INFO "remove from free list %lx %d %lx\n",
5904                        pfn, 1 << order, end_pfn);
5905 #endif
5906                 list_del(&page->lru);
5907                 rmv_page_order(page);
5908                 zone->free_area[order].nr_free--;
5909                 __mod_zone_page_state(zone, NR_FREE_PAGES,
5910                                       - (1UL << order));
5911                 for (i = 0; i < (1 << order); i++)
5912                         SetPageReserved((page+i));
5913                 pfn += (1 << order);
5914         }
5915         spin_unlock_irqrestore(&zone->lock, flags);
5916 }
5917 #endif
5918 
5919 #ifdef CONFIG_MEMORY_FAILURE
5920 bool is_free_buddy_page(struct page *page)
5921 {
5922         struct zone *zone = page_zone(page);
5923         unsigned long pfn = page_to_pfn(page);
5924         unsigned long flags;
5925         int order;
5926 
5927         spin_lock_irqsave(&zone->lock, flags);
5928         for (order = 0; order < MAX_ORDER; order++) {
5929                 struct page *page_head = page - (pfn & ((1 << order) - 1));
5930 
5931                 if (PageBuddy(page_head) && page_order(page_head) >= order)
5932                         break;
5933         }
5934         spin_unlock_irqrestore(&zone->lock, flags);
5935 
5936         return order < MAX_ORDER;
5937 }
5938 #endif
5939 
5940 static const struct trace_print_flags pageflag_names[] = {
5941         {1UL << PG_locked,              "locked"        },
5942         {1UL << PG_error,               "error"         },
5943         {1UL << PG_referenced,          "referenced"    },
5944         {1UL << PG_uptodate,            "uptodate"      },
5945         {1UL << PG_dirty,               "dirty"         },
5946         {1UL << PG_lru,                 "lru"           },
5947         {1UL << PG_active,              "active"        },
5948         {1UL << PG_slab,                "slab"          },
5949         {1UL << PG_owner_priv_1,        "owner_priv_1"  },
5950         {1UL << PG_arch_1,              "arch_1"        },
5951         {1UL << PG_reserved,            "reserved"      },
5952         {1UL << PG_private,             "private"       },
5953         {1UL << PG_private_2,           "private_2"     },
5954         {1UL << PG_writeback,           "writeback"     },
5955 #ifdef CONFIG_PAGEFLAGS_EXTENDED
5956         {1UL << PG_head,                "head"          },
5957         {1UL << PG_tail,                "tail"          },
5958 #else
5959         {1UL << PG_compound,            "compound"      },
5960 #endif
5961         {1UL << PG_swapcache,           "swapcache"     },
5962         {1UL << PG_mappedtodisk,        "mappedtodisk"  },
5963         {1UL << PG_reclaim,             "reclaim"       },
5964         {1UL << PG_swapbacked,          "swapbacked"    },
5965         {1UL << PG_unevictable,         "unevictable"   },
5966 #ifdef CONFIG_MMU
5967         {1UL << PG_mlocked,             "mlocked"       },
5968 #endif
5969 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
5970         {1UL << PG_uncached,            "uncached"      },
5971 #endif
5972 #ifdef CONFIG_MEMORY_FAILURE
5973         {1UL << PG_hwpoison,            "hwpoison"      },
5974 #endif
5975 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5976         {1UL << PG_compound_lock,       "compound_lock" },
5977 #endif
5978 };
5979 
5980 static void dump_page_flags(unsigned long flags)
5981 {
5982         const char *delim = "";
5983         unsigned long mask;
5984         int i;
5985 
5986         BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
5987 
5988         printk(KERN_ALERT "page flags: %#lx(", flags);
5989 
5990         /* remove zone id */
5991         flags &= (1UL << NR_PAGEFLAGS) - 1;
5992 
5993         for (i = 0; i < ARRAY_SIZE(pageflag_names) && flags; i++) {
5994 
5995                 mask = pageflag_names[i].mask;
5996                 if ((flags & mask) != mask)
5997                         continue;
5998 
5999                 flags &= ~mask;
6000                 printk("%s%s", delim, pageflag_names[i].name);
6001                 delim = "|";
6002         }
6003 
6004         /* check for left over flags */
6005         if (flags)
6006                 printk("%s%#lx", delim, flags);
6007 
6008         printk(")\n");
6009 }
6010 
6011 void dump_page(struct page *page)
6012 {
6013         printk(KERN_ALERT
6014                "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
6015                 page, atomic_read(&page->_count), page_mapcount(page),
6016                 page->mapping, page->index);
6017         dump_page_flags(page->flags);
6018         mem_cgroup_print_bad_page(page);
6019 }
6020 

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