1 #ifndef _LINUX_MMZONE_H
2 #define _LINUX_MMZONE_H
3
4 #ifndef __ASSEMBLY__
5 #ifndef __GENERATING_BOUNDS_H
6
7 #include <linux/spinlock.h>
8 #include <linux/list.h>
9 #include <linux/wait.h>
10 #include <linux/bitops.h>
11 #include <linux/cache.h>
12 #include <linux/threads.h>
13 #include <linux/numa.h>
14 #include <linux/init.h>
15 #include <linux/seqlock.h>
16 #include <linux/nodemask.h>
17 #include <linux/pageblock-flags.h>
18 #include <linux/page-flags-layout.h>
19 #include <linux/atomic.h>
20 #include <asm/page.h>
21
22 /* Free memory management - zoned buddy allocator. */
23 #ifndef CONFIG_FORCE_MAX_ZONEORDER
24 #define MAX_ORDER 11
25 #else
26 #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
27 #endif
28 #define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1))
29
30 /*
31 * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
32 * costly to service. That is between allocation orders which should
33 * coalesce naturally under reasonable reclaim pressure and those which
34 * will not.
35 */
36 #define PAGE_ALLOC_COSTLY_ORDER 3
37
38 enum {
39 MIGRATE_UNMOVABLE,
40 MIGRATE_RECLAIMABLE,
41 MIGRATE_MOVABLE,
42 MIGRATE_PCPTYPES, /* the number of types on the pcp lists */
43 MIGRATE_RESERVE = MIGRATE_PCPTYPES,
44 #ifdef CONFIG_CMA
45 /*
46 * MIGRATE_CMA migration type is designed to mimic the way
47 * ZONE_MOVABLE works. Only movable pages can be allocated
48 * from MIGRATE_CMA pageblocks and page allocator never
49 * implicitly change migration type of MIGRATE_CMA pageblock.
50 *
51 * The way to use it is to change migratetype of a range of
52 * pageblocks to MIGRATE_CMA which can be done by
53 * __free_pageblock_cma() function. What is important though
54 * is that a range of pageblocks must be aligned to
55 * MAX_ORDER_NR_PAGES should biggest page be bigger then
56 * a single pageblock.
57 */
58 MIGRATE_CMA,
59 #endif
60 #ifdef CONFIG_MEMORY_ISOLATION
61 MIGRATE_ISOLATE, /* can't allocate from here */
62 #endif
63 MIGRATE_TYPES
64 };
65
66 #ifdef CONFIG_CMA
67 # define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
68 #else
69 # define is_migrate_cma(migratetype) false
70 #endif
71
72 #define for_each_migratetype_order(order, type) \
73 for (order = 0; order < MAX_ORDER; order++) \
74 for (type = 0; type < MIGRATE_TYPES; type++)
75
76 extern int page_group_by_mobility_disabled;
77
78 static inline int get_pageblock_migratetype(struct page *page)
79 {
80 return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
81 }
82
83 struct free_area {
84 struct list_head free_list[MIGRATE_TYPES];
85 unsigned long nr_free;
86 };
87
88 struct pglist_data;
89
90 /*
91 * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
92 * So add a wild amount of padding here to ensure that they fall into separate
93 * cachelines. There are very few zone structures in the machine, so space
94 * consumption is not a concern here.
95 */
96 #if defined(CONFIG_SMP)
97 struct zone_padding {
98 char x[0];
99 } ____cacheline_internodealigned_in_smp;
100 #define ZONE_PADDING(name) struct zone_padding name;
101 #else
102 #define ZONE_PADDING(name)
103 #endif
104
105 enum zone_stat_item {
106 /* First 128 byte cacheline (assuming 64 bit words) */
107 NR_FREE_PAGES,
108 NR_LRU_BASE,
109 NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
110 NR_ACTIVE_ANON, /* " " " " " */
111 NR_INACTIVE_FILE, /* " " " " " */
112 NR_ACTIVE_FILE, /* " " " " " */
113 NR_UNEVICTABLE, /* " " " " " */
114 NR_MLOCK, /* mlock()ed pages found and moved off LRU */
115 NR_ANON_PAGES, /* Mapped anonymous pages */
116 NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
117 only modified from process context */
118 NR_FILE_PAGES,
119 NR_FILE_DIRTY,
120 NR_WRITEBACK,
121 NR_SLAB_RECLAIMABLE,
122 NR_SLAB_UNRECLAIMABLE,
123 NR_PAGETABLE, /* used for pagetables */
124 NR_KERNEL_STACK,
125 /* Second 128 byte cacheline */
126 NR_UNSTABLE_NFS, /* NFS unstable pages */
127 NR_BOUNCE,
128 NR_VMSCAN_WRITE,
129 NR_VMSCAN_IMMEDIATE, /* Prioritise for reclaim when writeback ends */
130 NR_WRITEBACK_TEMP, /* Writeback using temporary buffers */
131 NR_ISOLATED_ANON, /* Temporary isolated pages from anon lru */
132 NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */
133 NR_SHMEM, /* shmem pages (included tmpfs/GEM pages) */
134 NR_DIRTIED, /* page dirtyings since bootup */
135 NR_WRITTEN, /* page writings since bootup */
136 #ifdef CONFIG_NUMA
137 NUMA_HIT, /* allocated in intended node */
138 NUMA_MISS, /* allocated in non intended node */
139 NUMA_FOREIGN, /* was intended here, hit elsewhere */
140 NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
141 NUMA_LOCAL, /* allocation from local node */
142 NUMA_OTHER, /* allocation from other node */
143 #endif
144 NR_ANON_TRANSPARENT_HUGEPAGES,
145 NR_FREE_CMA_PAGES,
146 NR_VM_ZONE_STAT_ITEMS };
147
148 /*
149 * We do arithmetic on the LRU lists in various places in the code,
150 * so it is important to keep the active lists LRU_ACTIVE higher in
151 * the array than the corresponding inactive lists, and to keep
152 * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
153 *
154 * This has to be kept in sync with the statistics in zone_stat_item
155 * above and the descriptions in vmstat_text in mm/vmstat.c
156 */
157 #define LRU_BASE 0
158 #define LRU_ACTIVE 1
159 #define LRU_FILE 2
160
161 enum lru_list {
162 LRU_INACTIVE_ANON = LRU_BASE,
163 LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
164 LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
165 LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
166 LRU_UNEVICTABLE,
167 NR_LRU_LISTS
168 };
169
170 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
171
172 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
173
174 static inline int is_file_lru(enum lru_list lru)
175 {
176 return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
177 }
178
179 static inline int is_active_lru(enum lru_list lru)
180 {
181 return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
182 }
183
184 static inline int is_unevictable_lru(enum lru_list lru)
185 {
186 return (lru == LRU_UNEVICTABLE);
187 }
188
189 struct zone_reclaim_stat {
190 /*
191 * The pageout code in vmscan.c keeps track of how many of the
192 * mem/swap backed and file backed pages are referenced.
193 * The higher the rotated/scanned ratio, the more valuable
194 * that cache is.
195 *
196 * The anon LRU stats live in [0], file LRU stats in [1]
197 */
198 unsigned long recent_rotated[2];
199 unsigned long recent_scanned[2];
200 };
201
202 struct lruvec {
203 struct list_head lists[NR_LRU_LISTS];
204 struct zone_reclaim_stat reclaim_stat;
205 #ifdef CONFIG_MEMCG
206 struct zone *zone;
207 #endif
208 };
209
210 /* Mask used at gathering information at once (see memcontrol.c) */
211 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
212 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
213 #define LRU_ALL ((1 << NR_LRU_LISTS) - 1)
214
215 /* Isolate clean file */
216 #define ISOLATE_CLEAN ((__force isolate_mode_t)0x1)
217 /* Isolate unmapped file */
218 #define ISOLATE_UNMAPPED ((__force isolate_mode_t)0x2)
219 /* Isolate for asynchronous migration */
220 #define ISOLATE_ASYNC_MIGRATE ((__force isolate_mode_t)0x4)
221 /* Isolate unevictable pages */
222 #define ISOLATE_UNEVICTABLE ((__force isolate_mode_t)0x8)
223
224 /* LRU Isolation modes. */
225 typedef unsigned __bitwise__ isolate_mode_t;
226
227 enum zone_watermarks {
228 WMARK_MIN,
229 WMARK_LOW,
230 WMARK_HIGH,
231 NR_WMARK
232 };
233
234 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
235 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
236 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
237
238 struct per_cpu_pages {
239 int count; /* number of pages in the list */
240 int high; /* high watermark, emptying needed */
241 int batch; /* chunk size for buddy add/remove */
242
243 /* Lists of pages, one per migrate type stored on the pcp-lists */
244 struct list_head lists[MIGRATE_PCPTYPES];
245 };
246
247 struct per_cpu_pageset {
248 struct per_cpu_pages pcp;
249 #ifdef CONFIG_NUMA
250 s8 expire;
251 #endif
252 #ifdef CONFIG_SMP
253 s8 stat_threshold;
254 s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
255 #endif
256 };
257
258 #endif /* !__GENERATING_BOUNDS.H */
259
260 enum zone_type {
261 #ifdef CONFIG_ZONE_DMA
262 /*
263 * ZONE_DMA is used when there are devices that are not able
264 * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
265 * carve out the portion of memory that is needed for these devices.
266 * The range is arch specific.
267 *
268 * Some examples
269 *
270 * Architecture Limit
271 * ---------------------------
272 * parisc, ia64, sparc <4G
273 * s390 <2G
274 * arm Various
275 * alpha Unlimited or 0-16MB.
276 *
277 * i386, x86_64 and multiple other arches
278 * <16M.
279 */
280 ZONE_DMA,
281 #endif
282 #ifdef CONFIG_ZONE_DMA32
283 /*
284 * x86_64 needs two ZONE_DMAs because it supports devices that are
285 * only able to do DMA to the lower 16M but also 32 bit devices that
286 * can only do DMA areas below 4G.
287 */
288 ZONE_DMA32,
289 #endif
290 /*
291 * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
292 * performed on pages in ZONE_NORMAL if the DMA devices support
293 * transfers to all addressable memory.
294 */
295 ZONE_NORMAL,
296 #ifdef CONFIG_HIGHMEM
297 /*
298 * A memory area that is only addressable by the kernel through
299 * mapping portions into its own address space. This is for example
300 * used by i386 to allow the kernel to address the memory beyond
301 * 900MB. The kernel will set up special mappings (page
302 * table entries on i386) for each page that the kernel needs to
303 * access.
304 */
305 ZONE_HIGHMEM,
306 #endif
307 ZONE_MOVABLE,
308 __MAX_NR_ZONES
309 };
310
311 #ifndef __GENERATING_BOUNDS_H
312
313 struct zone {
314 /* Fields commonly accessed by the page allocator */
315
316 /* zone watermarks, access with *_wmark_pages(zone) macros */
317 unsigned long watermark[NR_WMARK];
318
319 /*
320 * When free pages are below this point, additional steps are taken
321 * when reading the number of free pages to avoid per-cpu counter
322 * drift allowing watermarks to be breached
323 */
324 unsigned long percpu_drift_mark;
325
326 /*
327 * We don't know if the memory that we're going to allocate will be freeable
328 * or/and it will be released eventually, so to avoid totally wasting several
329 * GB of ram we must reserve some of the lower zone memory (otherwise we risk
330 * to run OOM on the lower zones despite there's tons of freeable ram
331 * on the higher zones). This array is recalculated at runtime if the
332 * sysctl_lowmem_reserve_ratio sysctl changes.
333 */
334 unsigned long lowmem_reserve[MAX_NR_ZONES];
335
336 /*
337 * This is a per-zone reserve of pages that should not be
338 * considered dirtyable memory.
339 */
340 unsigned long dirty_balance_reserve;
341
342 #ifdef CONFIG_NUMA
343 int node;
344 /*
345 * zone reclaim becomes active if more unmapped pages exist.
346 */
347 unsigned long min_unmapped_pages;
348 unsigned long min_slab_pages;
349 #endif
350 struct per_cpu_pageset __percpu *pageset;
351 /*
352 * free areas of different sizes
353 */
354 spinlock_t lock;
355 int all_unreclaimable; /* All pages pinned */
356 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
357 /* Set to true when the PG_migrate_skip bits should be cleared */
358 bool compact_blockskip_flush;
359
360 /* pfns where compaction scanners should start */
361 unsigned long compact_cached_free_pfn;
362 unsigned long compact_cached_migrate_pfn;
363 #endif
364 #ifdef CONFIG_MEMORY_HOTPLUG
365 /* see spanned/present_pages for more description */
366 seqlock_t span_seqlock;
367 #endif
368 struct free_area free_area[MAX_ORDER];
369
370 #ifndef CONFIG_SPARSEMEM
371 /*
372 * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
373 * In SPARSEMEM, this map is stored in struct mem_section
374 */
375 unsigned long *pageblock_flags;
376 #endif /* CONFIG_SPARSEMEM */
377
378 #ifdef CONFIG_COMPACTION
379 /*
380 * On compaction failure, 1<<compact_defer_shift compactions
381 * are skipped before trying again. The number attempted since
382 * last failure is tracked with compact_considered.
383 */
384 unsigned int compact_considered;
385 unsigned int compact_defer_shift;
386 int compact_order_failed;
387 #endif
388
389 ZONE_PADDING(_pad1_)
390
391 /* Fields commonly accessed by the page reclaim scanner */
392 spinlock_t lru_lock;
393 struct lruvec lruvec;
394
395 unsigned long pages_scanned; /* since last reclaim */
396 unsigned long flags; /* zone flags, see below */
397
398 /* Zone statistics */
399 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
400
401 /*
402 * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
403 * this zone's LRU. Maintained by the pageout code.
404 */
405 unsigned int inactive_ratio;
406
407
408 ZONE_PADDING(_pad2_)
409 /* Rarely used or read-mostly fields */
410
411 /*
412 * wait_table -- the array holding the hash table
413 * wait_table_hash_nr_entries -- the size of the hash table array
414 * wait_table_bits -- wait_table_size == (1 << wait_table_bits)
415 *
416 * The purpose of all these is to keep track of the people
417 * waiting for a page to become available and make them
418 * runnable again when possible. The trouble is that this
419 * consumes a lot of space, especially when so few things
420 * wait on pages at a given time. So instead of using
421 * per-page waitqueues, we use a waitqueue hash table.
422 *
423 * The bucket discipline is to sleep on the same queue when
424 * colliding and wake all in that wait queue when removing.
425 * When something wakes, it must check to be sure its page is
426 * truly available, a la thundering herd. The cost of a
427 * collision is great, but given the expected load of the
428 * table, they should be so rare as to be outweighed by the
429 * benefits from the saved space.
430 *
431 * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
432 * primary users of these fields, and in mm/page_alloc.c
433 * free_area_init_core() performs the initialization of them.
434 */
435 wait_queue_head_t * wait_table;
436 unsigned long wait_table_hash_nr_entries;
437 unsigned long wait_table_bits;
438
439 /*
440 * Discontig memory support fields.
441 */
442 struct pglist_data *zone_pgdat;
443 /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
444 unsigned long zone_start_pfn;
445
446 /*
447 * spanned_pages is the total pages spanned by the zone, including
448 * holes, which is calculated as:
449 * spanned_pages = zone_end_pfn - zone_start_pfn;
450 *
451 * present_pages is physical pages existing within the zone, which
452 * is calculated as:
453 * present_pages = spanned_pages - absent_pages(pages in holes);
454 *
455 * managed_pages is present pages managed by the buddy system, which
456 * is calculated as (reserved_pages includes pages allocated by the
457 * bootmem allocator):
458 * managed_pages = present_pages - reserved_pages;
459 *
460 * So present_pages may be used by memory hotplug or memory power
461 * management logic to figure out unmanaged pages by checking
462 * (present_pages - managed_pages). And managed_pages should be used
463 * by page allocator and vm scanner to calculate all kinds of watermarks
464 * and thresholds.
465 *
466 * Locking rules:
467 *
468 * zone_start_pfn and spanned_pages are protected by span_seqlock.
469 * It is a seqlock because it has to be read outside of zone->lock,
470 * and it is done in the main allocator path. But, it is written
471 * quite infrequently.
472 *
473 * The span_seq lock is declared along with zone->lock because it is
474 * frequently read in proximity to zone->lock. It's good to
475 * give them a chance of being in the same cacheline.
476 *
477 * Write access to present_pages and managed_pages at runtime should
478 * be protected by lock_memory_hotplug()/unlock_memory_hotplug().
479 * Any reader who can't tolerant drift of present_pages and
480 * managed_pages should hold memory hotplug lock to get a stable value.
481 */
482 unsigned long spanned_pages;
483 unsigned long present_pages;
484 unsigned long managed_pages;
485
486 /*
487 * rarely used fields:
488 */
489 const char *name;
490 } ____cacheline_internodealigned_in_smp;
491
492 typedef enum {
493 ZONE_RECLAIM_LOCKED, /* prevents concurrent reclaim */
494 ZONE_OOM_LOCKED, /* zone is in OOM killer zonelist */
495 ZONE_CONGESTED, /* zone has many dirty pages backed by
496 * a congested BDI
497 */
498 } zone_flags_t;
499
500 static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
501 {
502 set_bit(flag, &zone->flags);
503 }
504
505 static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
506 {
507 return test_and_set_bit(flag, &zone->flags);
508 }
509
510 static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
511 {
512 clear_bit(flag, &zone->flags);
513 }
514
515 static inline int zone_is_reclaim_congested(const struct zone *zone)
516 {
517 return test_bit(ZONE_CONGESTED, &zone->flags);
518 }
519
520 static inline int zone_is_reclaim_locked(const struct zone *zone)
521 {
522 return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
523 }
524
525 static inline int zone_is_oom_locked(const struct zone *zone)
526 {
527 return test_bit(ZONE_OOM_LOCKED, &zone->flags);
528 }
529
530 static inline unsigned long zone_end_pfn(const struct zone *zone)
531 {
532 return zone->zone_start_pfn + zone->spanned_pages;
533 }
534
535 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
536 {
537 return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
538 }
539
540 static inline bool zone_is_initialized(struct zone *zone)
541 {
542 return !!zone->wait_table;
543 }
544
545 static inline bool zone_is_empty(struct zone *zone)
546 {
547 return zone->spanned_pages == 0;
548 }
549
550 /*
551 * The "priority" of VM scanning is how much of the queues we will scan in one
552 * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
553 * queues ("queue_length >> 12") during an aging round.
554 */
555 #define DEF_PRIORITY 12
556
557 /* Maximum number of zones on a zonelist */
558 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
559
560 #ifdef CONFIG_NUMA
561
562 /*
563 * The NUMA zonelists are doubled because we need zonelists that restrict the
564 * allocations to a single node for GFP_THISNODE.
565 *
566 * [0] : Zonelist with fallback
567 * [1] : No fallback (GFP_THISNODE)
568 */
569 #define MAX_ZONELISTS 2
570
571
572 /*
573 * We cache key information from each zonelist for smaller cache
574 * footprint when scanning for free pages in get_page_from_freelist().
575 *
576 * 1) The BITMAP fullzones tracks which zones in a zonelist have come
577 * up short of free memory since the last time (last_fullzone_zap)
578 * we zero'd fullzones.
579 * 2) The array z_to_n[] maps each zone in the zonelist to its node
580 * id, so that we can efficiently evaluate whether that node is
581 * set in the current tasks mems_allowed.
582 *
583 * Both fullzones and z_to_n[] are one-to-one with the zonelist,
584 * indexed by a zones offset in the zonelist zones[] array.
585 *
586 * The get_page_from_freelist() routine does two scans. During the
587 * first scan, we skip zones whose corresponding bit in 'fullzones'
588 * is set or whose corresponding node in current->mems_allowed (which
589 * comes from cpusets) is not set. During the second scan, we bypass
590 * this zonelist_cache, to ensure we look methodically at each zone.
591 *
592 * Once per second, we zero out (zap) fullzones, forcing us to
593 * reconsider nodes that might have regained more free memory.
594 * The field last_full_zap is the time we last zapped fullzones.
595 *
596 * This mechanism reduces the amount of time we waste repeatedly
597 * reexaming zones for free memory when they just came up low on
598 * memory momentarilly ago.
599 *
600 * The zonelist_cache struct members logically belong in struct
601 * zonelist. However, the mempolicy zonelists constructed for
602 * MPOL_BIND are intentionally variable length (and usually much
603 * shorter). A general purpose mechanism for handling structs with
604 * multiple variable length members is more mechanism than we want
605 * here. We resort to some special case hackery instead.
606 *
607 * The MPOL_BIND zonelists don't need this zonelist_cache (in good
608 * part because they are shorter), so we put the fixed length stuff
609 * at the front of the zonelist struct, ending in a variable length
610 * zones[], as is needed by MPOL_BIND.
611 *
612 * Then we put the optional zonelist cache on the end of the zonelist
613 * struct. This optional stuff is found by a 'zlcache_ptr' pointer in
614 * the fixed length portion at the front of the struct. This pointer
615 * both enables us to find the zonelist cache, and in the case of
616 * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
617 * to know that the zonelist cache is not there.
618 *
619 * The end result is that struct zonelists come in two flavors:
620 * 1) The full, fixed length version, shown below, and
621 * 2) The custom zonelists for MPOL_BIND.
622 * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
623 *
624 * Even though there may be multiple CPU cores on a node modifying
625 * fullzones or last_full_zap in the same zonelist_cache at the same
626 * time, we don't lock it. This is just hint data - if it is wrong now
627 * and then, the allocator will still function, perhaps a bit slower.
628 */
629
630
631 struct zonelist_cache {
632 unsigned short z_to_n[MAX_ZONES_PER_ZONELIST]; /* zone->nid */
633 DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST); /* zone full? */
634 unsigned long last_full_zap; /* when last zap'd (jiffies) */
635 };
636 #else
637 #define MAX_ZONELISTS 1
638 struct zonelist_cache;
639 #endif
640
641 /*
642 * This struct contains information about a zone in a zonelist. It is stored
643 * here to avoid dereferences into large structures and lookups of tables
644 */
645 struct zoneref {
646 struct zone *zone; /* Pointer to actual zone */
647 int zone_idx; /* zone_idx(zoneref->zone) */
648 };
649
650 /*
651 * One allocation request operates on a zonelist. A zonelist
652 * is a list of zones, the first one is the 'goal' of the
653 * allocation, the other zones are fallback zones, in decreasing
654 * priority.
655 *
656 * If zlcache_ptr is not NULL, then it is just the address of zlcache,
657 * as explained above. If zlcache_ptr is NULL, there is no zlcache.
658 * *
659 * To speed the reading of the zonelist, the zonerefs contain the zone index
660 * of the entry being read. Helper functions to access information given
661 * a struct zoneref are
662 *
663 * zonelist_zone() - Return the struct zone * for an entry in _zonerefs
664 * zonelist_zone_idx() - Return the index of the zone for an entry
665 * zonelist_node_idx() - Return the index of the node for an entry
666 */
667 struct zonelist {
668 struct zonelist_cache *zlcache_ptr; // NULL or &zlcache
669 struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
670 #ifdef CONFIG_NUMA
671 struct zonelist_cache zlcache; // optional ...
672 #endif
673 };
674
675 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
676 struct node_active_region {
677 unsigned long start_pfn;
678 unsigned long end_pfn;
679 int nid;
680 };
681 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
682
683 #ifndef CONFIG_DISCONTIGMEM
684 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
685 extern struct page *mem_map;
686 #endif
687
688 /*
689 * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
690 * (mostly NUMA machines?) to denote a higher-level memory zone than the
691 * zone denotes.
692 *
693 * On NUMA machines, each NUMA node would have a pg_data_t to describe
694 * it's memory layout.
695 *
696 * Memory statistics and page replacement data structures are maintained on a
697 * per-zone basis.
698 */
699 struct bootmem_data;
700 typedef struct pglist_data {
701 struct zone node_zones[MAX_NR_ZONES];
702 struct zonelist node_zonelists[MAX_ZONELISTS];
703 int nr_zones;
704 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
705 struct page *node_mem_map;
706 #ifdef CONFIG_MEMCG
707 struct page_cgroup *node_page_cgroup;
708 #endif
709 #endif
710 #ifndef CONFIG_NO_BOOTMEM
711 struct bootmem_data *bdata;
712 #endif
713 #ifdef CONFIG_MEMORY_HOTPLUG
714 /*
715 * Must be held any time you expect node_start_pfn, node_present_pages
716 * or node_spanned_pages stay constant. Holding this will also
717 * guarantee that any pfn_valid() stays that way.
718 *
719 * Nests above zone->lock and zone->size_seqlock.
720 */
721 spinlock_t node_size_lock;
722 #endif
723 unsigned long node_start_pfn;
724 unsigned long node_present_pages; /* total number of physical pages */
725 unsigned long node_spanned_pages; /* total size of physical page
726 range, including holes */
727 int node_id;
728 nodemask_t reclaim_nodes; /* Nodes allowed to reclaim from */
729 wait_queue_head_t kswapd_wait;
730 wait_queue_head_t pfmemalloc_wait;
731 struct task_struct *kswapd; /* Protected by lock_memory_hotplug() */
732 int kswapd_max_order;
733 enum zone_type classzone_idx;
734 #ifdef CONFIG_NUMA_BALANCING
735 /*
736 * Lock serializing the per destination node AutoNUMA memory
737 * migration rate limiting data.
738 */
739 spinlock_t numabalancing_migrate_lock;
740
741 /* Rate limiting time interval */
742 unsigned long numabalancing_migrate_next_window;
743
744 /* Number of pages migrated during the rate limiting time interval */
745 unsigned long numabalancing_migrate_nr_pages;
746 #endif
747 } pg_data_t;
748
749 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
750 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
751 #ifdef CONFIG_FLAT_NODE_MEM_MAP
752 #define pgdat_page_nr(pgdat, pagenr) ((pgdat)->node_mem_map + (pagenr))
753 #else
754 #define pgdat_page_nr(pgdat, pagenr) pfn_to_page((pgdat)->node_start_pfn + (pagenr))
755 #endif
756 #define nid_page_nr(nid, pagenr) pgdat_page_nr(NODE_DATA(nid),(pagenr))
757
758 #define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn)
759 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
760
761 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
762 {
763 return pgdat->node_start_pfn + pgdat->node_spanned_pages;
764 }
765
766 static inline bool pgdat_is_empty(pg_data_t *pgdat)
767 {
768 return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
769 }
770
771 #include <linux/memory_hotplug.h>
772
773 extern struct mutex zonelists_mutex;
774 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
775 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
776 bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
777 int classzone_idx, int alloc_flags);
778 bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
779 int classzone_idx, int alloc_flags);
780 enum memmap_context {
781 MEMMAP_EARLY,
782 MEMMAP_HOTPLUG,
783 };
784 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
785 unsigned long size,
786 enum memmap_context context);
787
788 extern void lruvec_init(struct lruvec *lruvec);
789
790 static inline struct zone *lruvec_zone(struct lruvec *lruvec)
791 {
792 #ifdef CONFIG_MEMCG
793 return lruvec->zone;
794 #else
795 return container_of(lruvec, struct zone, lruvec);
796 #endif
797 }
798
799 #ifdef CONFIG_HAVE_MEMORY_PRESENT
800 void memory_present(int nid, unsigned long start, unsigned long end);
801 #else
802 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
803 #endif
804
805 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
806 int local_memory_node(int node_id);
807 #else
808 static inline int local_memory_node(int node_id) { return node_id; };
809 #endif
810
811 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
812 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
813 #endif
814
815 /*
816 * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
817 */
818 #define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones)
819
820 static inline int populated_zone(struct zone *zone)
821 {
822 return (!!zone->present_pages);
823 }
824
825 extern int movable_zone;
826
827 static inline int zone_movable_is_highmem(void)
828 {
829 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
830 return movable_zone == ZONE_HIGHMEM;
831 #else
832 return 0;
833 #endif
834 }
835
836 static inline int is_highmem_idx(enum zone_type idx)
837 {
838 #ifdef CONFIG_HIGHMEM
839 return (idx == ZONE_HIGHMEM ||
840 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
841 #else
842 return 0;
843 #endif
844 }
845
846 static inline int is_normal_idx(enum zone_type idx)
847 {
848 return (idx == ZONE_NORMAL);
849 }
850
851 /**
852 * is_highmem - helper function to quickly check if a struct zone is a
853 * highmem zone or not. This is an attempt to keep references
854 * to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
855 * @zone - pointer to struct zone variable
856 */
857 static inline int is_highmem(struct zone *zone)
858 {
859 #ifdef CONFIG_HIGHMEM
860 int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
861 return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
862 (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
863 zone_movable_is_highmem());
864 #else
865 return 0;
866 #endif
867 }
868
869 static inline int is_normal(struct zone *zone)
870 {
871 return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
872 }
873
874 static inline int is_dma32(struct zone *zone)
875 {
876 #ifdef CONFIG_ZONE_DMA32
877 return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
878 #else
879 return 0;
880 #endif
881 }
882
883 static inline int is_dma(struct zone *zone)
884 {
885 #ifdef CONFIG_ZONE_DMA
886 return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
887 #else
888 return 0;
889 #endif
890 }
891
892 /* These two functions are used to setup the per zone pages min values */
893 struct ctl_table;
894 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
895 void __user *, size_t *, loff_t *);
896 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
897 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
898 void __user *, size_t *, loff_t *);
899 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
900 void __user *, size_t *, loff_t *);
901 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
902 void __user *, size_t *, loff_t *);
903 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
904 void __user *, size_t *, loff_t *);
905
906 extern int numa_zonelist_order_handler(struct ctl_table *, int,
907 void __user *, size_t *, loff_t *);
908 extern char numa_zonelist_order[];
909 #define NUMA_ZONELIST_ORDER_LEN 16 /* string buffer size */
910
911 #ifndef CONFIG_NEED_MULTIPLE_NODES
912
913 extern struct pglist_data contig_page_data;
914 #define NODE_DATA(nid) (&contig_page_data)
915 #define NODE_MEM_MAP(nid) mem_map
916
917 #else /* CONFIG_NEED_MULTIPLE_NODES */
918
919 #include <asm/mmzone.h>
920
921 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
922
923 extern struct pglist_data *first_online_pgdat(void);
924 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
925 extern struct zone *next_zone(struct zone *zone);
926
927 /**
928 * for_each_online_pgdat - helper macro to iterate over all online nodes
929 * @pgdat - pointer to a pg_data_t variable
930 */
931 #define for_each_online_pgdat(pgdat) \
932 for (pgdat = first_online_pgdat(); \
933 pgdat; \
934 pgdat = next_online_pgdat(pgdat))
935 /**
936 * for_each_zone - helper macro to iterate over all memory zones
937 * @zone - pointer to struct zone variable
938 *
939 * The user only needs to declare the zone variable, for_each_zone
940 * fills it in.
941 */
942 #define for_each_zone(zone) \
943 for (zone = (first_online_pgdat())->node_zones; \
944 zone; \
945 zone = next_zone(zone))
946
947 #define for_each_populated_zone(zone) \
948 for (zone = (first_online_pgdat())->node_zones; \
949 zone; \
950 zone = next_zone(zone)) \
951 if (!populated_zone(zone)) \
952 ; /* do nothing */ \
953 else
954
955 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
956 {
957 return zoneref->zone;
958 }
959
960 static inline int zonelist_zone_idx(struct zoneref *zoneref)
961 {
962 return zoneref->zone_idx;
963 }
964
965 static inline int zonelist_node_idx(struct zoneref *zoneref)
966 {
967 #ifdef CONFIG_NUMA
968 /* zone_to_nid not available in this context */
969 return zoneref->zone->node;
970 #else
971 return 0;
972 #endif /* CONFIG_NUMA */
973 }
974
975 /**
976 * next_zones_zonelist - Returns the next zone at or below highest_zoneidx within the allowed nodemask using a cursor within a zonelist as a starting point
977 * @z - The cursor used as a starting point for the search
978 * @highest_zoneidx - The zone index of the highest zone to return
979 * @nodes - An optional nodemask to filter the zonelist with
980 * @zone - The first suitable zone found is returned via this parameter
981 *
982 * This function returns the next zone at or below a given zone index that is
983 * within the allowed nodemask using a cursor as the starting point for the
984 * search. The zoneref returned is a cursor that represents the current zone
985 * being examined. It should be advanced by one before calling
986 * next_zones_zonelist again.
987 */
988 struct zoneref *next_zones_zonelist(struct zoneref *z,
989 enum zone_type highest_zoneidx,
990 nodemask_t *nodes,
991 struct zone **zone);
992
993 /**
994 * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
995 * @zonelist - The zonelist to search for a suitable zone
996 * @highest_zoneidx - The zone index of the highest zone to return
997 * @nodes - An optional nodemask to filter the zonelist with
998 * @zone - The first suitable zone found is returned via this parameter
999 *
1000 * This function returns the first zone at or below a given zone index that is
1001 * within the allowed nodemask. The zoneref returned is a cursor that can be
1002 * used to iterate the zonelist with next_zones_zonelist by advancing it by
1003 * one before calling.
1004 */
1005 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
1006 enum zone_type highest_zoneidx,
1007 nodemask_t *nodes,
1008 struct zone **zone)
1009 {
1010 return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
1011 zone);
1012 }
1013
1014 /**
1015 * for_each_zone_zonelist_nodemask - helper macro to iterate over valid zones in a zonelist at or below a given zone index and within a nodemask
1016 * @zone - The current zone in the iterator
1017 * @z - The current pointer within zonelist->zones being iterated
1018 * @zlist - The zonelist being iterated
1019 * @highidx - The zone index of the highest zone to return
1020 * @nodemask - Nodemask allowed by the allocator
1021 *
1022 * This iterator iterates though all zones at or below a given zone index and
1023 * within a given nodemask
1024 */
1025 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1026 for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
1027 zone; \
1028 z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
1029
1030 /**
1031 * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1032 * @zone - The current zone in the iterator
1033 * @z - The current pointer within zonelist->zones being iterated
1034 * @zlist - The zonelist being iterated
1035 * @highidx - The zone index of the highest zone to return
1036 *
1037 * This iterator iterates though all zones at or below a given zone index.
1038 */
1039 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1040 for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1041
1042 #ifdef CONFIG_SPARSEMEM
1043 #include <asm/sparsemem.h>
1044 #endif
1045
1046 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1047 !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1048 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1049 {
1050 return 0;
1051 }
1052 #endif
1053
1054 #ifdef CONFIG_FLATMEM
1055 #define pfn_to_nid(pfn) (0)
1056 #endif
1057
1058 #ifdef CONFIG_SPARSEMEM
1059
1060 /*
1061 * SECTION_SHIFT #bits space required to store a section #
1062 *
1063 * PA_SECTION_SHIFT physical address to/from section number
1064 * PFN_SECTION_SHIFT pfn to/from section number
1065 */
1066 #define PA_SECTION_SHIFT (SECTION_SIZE_BITS)
1067 #define PFN_SECTION_SHIFT (SECTION_SIZE_BITS - PAGE_SHIFT)
1068
1069 #define NR_MEM_SECTIONS (1UL << SECTIONS_SHIFT)
1070
1071 #define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT)
1072 #define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1))
1073
1074 #define SECTION_BLOCKFLAGS_BITS \
1075 ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1076
1077 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1078 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1079 #endif
1080
1081 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1082 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1083
1084 #define SECTION_ALIGN_UP(pfn) (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1085 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1086
1087 struct page;
1088 struct page_cgroup;
1089 struct mem_section {
1090 /*
1091 * This is, logically, a pointer to an array of struct
1092 * pages. However, it is stored with some other magic.
1093 * (see sparse.c::sparse_init_one_section())
1094 *
1095 * Additionally during early boot we encode node id of
1096 * the location of the section here to guide allocation.
1097 * (see sparse.c::memory_present())
1098 *
1099 * Making it a UL at least makes someone do a cast
1100 * before using it wrong.
1101 */
1102 unsigned long section_mem_map;
1103
1104 /* See declaration of similar field in struct zone */
1105 unsigned long *pageblock_flags;
1106 #ifdef CONFIG_MEMCG
1107 /*
1108 * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1109 * section. (see memcontrol.h/page_cgroup.h about this.)
1110 */
1111 struct page_cgroup *page_cgroup;
1112 unsigned long pad;
1113 #endif
1114 };
1115
1116 #ifdef CONFIG_SPARSEMEM_EXTREME
1117 #define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section))
1118 #else
1119 #define SECTIONS_PER_ROOT 1
1120 #endif
1121
1122 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1123 #define NR_SECTION_ROOTS DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1124 #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
1125
1126 #ifdef CONFIG_SPARSEMEM_EXTREME
1127 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1128 #else
1129 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1130 #endif
1131
1132 static inline struct mem_section *__nr_to_section(unsigned long nr)
1133 {
1134 if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1135 return NULL;
1136 return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1137 }
1138 extern int __section_nr(struct mem_section* ms);
1139 extern unsigned long usemap_size(void);
1140
1141 /*
1142 * We use the lower bits of the mem_map pointer to store
1143 * a little bit of information. There should be at least
1144 * 3 bits here due to 32-bit alignment.
1145 */
1146 #define SECTION_MARKED_PRESENT (1UL<<0)
1147 #define SECTION_HAS_MEM_MAP (1UL<<1)
1148 #define SECTION_MAP_LAST_BIT (1UL<<2)
1149 #define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1))
1150 #define SECTION_NID_SHIFT 2
1151
1152 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1153 {
1154 unsigned long map = section->section_mem_map;
1155 map &= SECTION_MAP_MASK;
1156 return (struct page *)map;
1157 }
1158
1159 static inline int present_section(struct mem_section *section)
1160 {
1161 return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1162 }
1163
1164 static inline int present_section_nr(unsigned long nr)
1165 {
1166 return present_section(__nr_to_section(nr));
1167 }
1168
1169 static inline int valid_section(struct mem_section *section)
1170 {
1171 return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1172 }
1173
1174 static inline int valid_section_nr(unsigned long nr)
1175 {
1176 return valid_section(__nr_to_section(nr));
1177 }
1178
1179 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1180 {
1181 return __nr_to_section(pfn_to_section_nr(pfn));
1182 }
1183
1184 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1185 static inline int pfn_valid(unsigned long pfn)
1186 {
1187 if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1188 return 0;
1189 return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1190 }
1191 #endif
1192
1193 static inline int pfn_present(unsigned long pfn)
1194 {
1195 if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1196 return 0;
1197 return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1198 }
1199
1200 /*
1201 * These are _only_ used during initialisation, therefore they
1202 * can use __initdata ... They could have names to indicate
1203 * this restriction.
1204 */
1205 #ifdef CONFIG_NUMA
1206 #define pfn_to_nid(pfn) \
1207 ({ \
1208 unsigned long __pfn_to_nid_pfn = (pfn); \
1209 page_to_nid(pfn_to_page(__pfn_to_nid_pfn)); \
1210 })
1211 #else
1212 #define pfn_to_nid(pfn) (0)
1213 #endif
1214
1215 #define early_pfn_valid(pfn) pfn_valid(pfn)
1216 void sparse_init(void);
1217 #else
1218 #define sparse_init() do {} while (0)
1219 #define sparse_index_init(_sec, _nid) do {} while (0)
1220 #endif /* CONFIG_SPARSEMEM */
1221
1222 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
1223 bool early_pfn_in_nid(unsigned long pfn, int nid);
1224 #else
1225 #define early_pfn_in_nid(pfn, nid) (1)
1226 #endif
1227
1228 #ifndef early_pfn_valid
1229 #define early_pfn_valid(pfn) (1)
1230 #endif
1231
1232 void memory_present(int nid, unsigned long start, unsigned long end);
1233 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1234
1235 /*
1236 * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1237 * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1238 * pfn_valid_within() should be used in this case; we optimise this away
1239 * when we have no holes within a MAX_ORDER_NR_PAGES block.
1240 */
1241 #ifdef CONFIG_HOLES_IN_ZONE
1242 #define pfn_valid_within(pfn) pfn_valid(pfn)
1243 #else
1244 #define pfn_valid_within(pfn) (1)
1245 #endif
1246
1247 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1248 /*
1249 * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1250 * associated with it or not. In FLATMEM, it is expected that holes always
1251 * have valid memmap as long as there is valid PFNs either side of the hole.
1252 * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1253 * entire section.
1254 *
1255 * However, an ARM, and maybe other embedded architectures in the future
1256 * free memmap backing holes to save memory on the assumption the memmap is
1257 * never used. The page_zone linkages are then broken even though pfn_valid()
1258 * returns true. A walker of the full memmap must then do this additional
1259 * check to ensure the memmap they are looking at is sane by making sure
1260 * the zone and PFN linkages are still valid. This is expensive, but walkers
1261 * of the full memmap are extremely rare.
1262 */
1263 int memmap_valid_within(unsigned long pfn,
1264 struct page *page, struct zone *zone);
1265 #else
1266 static inline int memmap_valid_within(unsigned long pfn,
1267 struct page *page, struct zone *zone)
1268 {
1269 return 1;
1270 }
1271 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1272
1273 #endif /* !__GENERATING_BOUNDS.H */
1274 #endif /* !__ASSEMBLY__ */
1275 #endif /* _LINUX_MMZONE_H */
1276
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