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TOMOYO Linux Cross Reference
Linux/include/linux/mmzone.h

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  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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