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Linux/include/linux/mmzone.h

  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 #define NR_MIGRATETYPE_BITS (PB_migrate_end - PB_migrate + 1)
 79 #define MIGRATETYPE_MASK ((1UL << NR_MIGRATETYPE_BITS) - 1)
 80 
 81 #define get_pageblock_migratetype(page)                                 \
 82         get_pfnblock_flags_mask(page, page_to_pfn(page),                \
 83                         PB_migrate_end, MIGRATETYPE_MASK)
 84 
 85 static inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
 86 {
 87         BUILD_BUG_ON(PB_migrate_end - PB_migrate != 2);
 88         return get_pfnblock_flags_mask(page, pfn, PB_migrate_end,
 89                                         MIGRATETYPE_MASK);
 90 }
 91 
 92 struct free_area {
 93         struct list_head        free_list[MIGRATE_TYPES];
 94         unsigned long           nr_free;
 95 };
 96 
 97 struct pglist_data;
 98 
 99 /*
100  * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
101  * So add a wild amount of padding here to ensure that they fall into separate
102  * cachelines.  There are very few zone structures in the machine, so space
103  * consumption is not a concern here.
104  */
105 #if defined(CONFIG_SMP)
106 struct zone_padding {
107         char x[0];
108 } ____cacheline_internodealigned_in_smp;
109 #define ZONE_PADDING(name)      struct zone_padding name;
110 #else
111 #define ZONE_PADDING(name)
112 #endif
113 
114 enum zone_stat_item {
115         /* First 128 byte cacheline (assuming 64 bit words) */
116         NR_FREE_PAGES,
117         NR_ALLOC_BATCH,
118         NR_LRU_BASE,
119         NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
120         NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
121         NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
122         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
123         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
124         NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
125         NR_ANON_PAGES,  /* Mapped anonymous pages */
126         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
127                            only modified from process context */
128         NR_FILE_PAGES,
129         NR_FILE_DIRTY,
130         NR_WRITEBACK,
131         NR_SLAB_RECLAIMABLE,
132         NR_SLAB_UNRECLAIMABLE,
133         NR_PAGETABLE,           /* used for pagetables */
134         NR_KERNEL_STACK,
135         /* Second 128 byte cacheline */
136         NR_UNSTABLE_NFS,        /* NFS unstable pages */
137         NR_BOUNCE,
138         NR_VMSCAN_WRITE,
139         NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
140         NR_WRITEBACK_TEMP,      /* Writeback using temporary buffers */
141         NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
142         NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
143         NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
144         NR_DIRTIED,             /* page dirtyings since bootup */
145         NR_WRITTEN,             /* page writings since bootup */
146 #ifdef CONFIG_NUMA
147         NUMA_HIT,               /* allocated in intended node */
148         NUMA_MISS,              /* allocated in non intended node */
149         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
150         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
151         NUMA_LOCAL,             /* allocation from local node */
152         NUMA_OTHER,             /* allocation from other node */
153 #endif
154         WORKINGSET_REFAULT,
155         WORKINGSET_ACTIVATE,
156         WORKINGSET_NODERECLAIM,
157         NR_ANON_TRANSPARENT_HUGEPAGES,
158         NR_FREE_CMA_PAGES,
159         NR_VM_ZONE_STAT_ITEMS };
160 
161 /*
162  * We do arithmetic on the LRU lists in various places in the code,
163  * so it is important to keep the active lists LRU_ACTIVE higher in
164  * the array than the corresponding inactive lists, and to keep
165  * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
166  *
167  * This has to be kept in sync with the statistics in zone_stat_item
168  * above and the descriptions in vmstat_text in mm/vmstat.c
169  */
170 #define LRU_BASE 0
171 #define LRU_ACTIVE 1
172 #define LRU_FILE 2
173 
174 enum lru_list {
175         LRU_INACTIVE_ANON = LRU_BASE,
176         LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
177         LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
178         LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
179         LRU_UNEVICTABLE,
180         NR_LRU_LISTS
181 };
182 
183 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
184 
185 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
186 
187 static inline int is_file_lru(enum lru_list lru)
188 {
189         return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
190 }
191 
192 static inline int is_active_lru(enum lru_list lru)
193 {
194         return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
195 }
196 
197 static inline int is_unevictable_lru(enum lru_list lru)
198 {
199         return (lru == LRU_UNEVICTABLE);
200 }
201 
202 struct zone_reclaim_stat {
203         /*
204          * The pageout code in vmscan.c keeps track of how many of the
205          * mem/swap backed and file backed pages are referenced.
206          * The higher the rotated/scanned ratio, the more valuable
207          * that cache is.
208          *
209          * The anon LRU stats live in [0], file LRU stats in [1]
210          */
211         unsigned long           recent_rotated[2];
212         unsigned long           recent_scanned[2];
213 };
214 
215 struct lruvec {
216         struct list_head lists[NR_LRU_LISTS];
217         struct zone_reclaim_stat reclaim_stat;
218 #ifdef CONFIG_MEMCG
219         struct zone *zone;
220 #endif
221 };
222 
223 /* Mask used at gathering information at once (see memcontrol.c) */
224 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
225 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
226 #define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
227 
228 /* Isolate clean file */
229 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
230 /* Isolate unmapped file */
231 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
232 /* Isolate for asynchronous migration */
233 #define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
234 /* Isolate unevictable pages */
235 #define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
236 
237 /* LRU Isolation modes. */
238 typedef unsigned __bitwise__ isolate_mode_t;
239 
240 enum zone_watermarks {
241         WMARK_MIN,
242         WMARK_LOW,
243         WMARK_HIGH,
244         NR_WMARK
245 };
246 
247 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
248 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
249 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
250 
251 struct per_cpu_pages {
252         int count;              /* number of pages in the list */
253         int high;               /* high watermark, emptying needed */
254         int batch;              /* chunk size for buddy add/remove */
255 
256         /* Lists of pages, one per migrate type stored on the pcp-lists */
257         struct list_head lists[MIGRATE_PCPTYPES];
258 };
259 
260 struct per_cpu_pageset {
261         struct per_cpu_pages pcp;
262 #ifdef CONFIG_NUMA
263         s8 expire;
264 #endif
265 #ifdef CONFIG_SMP
266         s8 stat_threshold;
267         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
268 #endif
269 };
270 
271 #endif /* !__GENERATING_BOUNDS.H */
272 
273 enum zone_type {
274 #ifdef CONFIG_ZONE_DMA
275         /*
276          * ZONE_DMA is used when there are devices that are not able
277          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
278          * carve out the portion of memory that is needed for these devices.
279          * The range is arch specific.
280          *
281          * Some examples
282          *
283          * Architecture         Limit
284          * ---------------------------
285          * parisc, ia64, sparc  <4G
286          * s390                 <2G
287          * arm                  Various
288          * alpha                Unlimited or 0-16MB.
289          *
290          * i386, x86_64 and multiple other arches
291          *                      <16M.
292          */
293         ZONE_DMA,
294 #endif
295 #ifdef CONFIG_ZONE_DMA32
296         /*
297          * x86_64 needs two ZONE_DMAs because it supports devices that are
298          * only able to do DMA to the lower 16M but also 32 bit devices that
299          * can only do DMA areas below 4G.
300          */
301         ZONE_DMA32,
302 #endif
303         /*
304          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
305          * performed on pages in ZONE_NORMAL if the DMA devices support
306          * transfers to all addressable memory.
307          */
308         ZONE_NORMAL,
309 #ifdef CONFIG_HIGHMEM
310         /*
311          * A memory area that is only addressable by the kernel through
312          * mapping portions into its own address space. This is for example
313          * used by i386 to allow the kernel to address the memory beyond
314          * 900MB. The kernel will set up special mappings (page
315          * table entries on i386) for each page that the kernel needs to
316          * access.
317          */
318         ZONE_HIGHMEM,
319 #endif
320         ZONE_MOVABLE,
321         __MAX_NR_ZONES
322 };
323 
324 #ifndef __GENERATING_BOUNDS_H
325 
326 struct zone {
327         /* Fields commonly accessed by the page allocator */
328 
329         /* zone watermarks, access with *_wmark_pages(zone) macros */
330         unsigned long watermark[NR_WMARK];
331 
332         /*
333          * When free pages are below this point, additional steps are taken
334          * when reading the number of free pages to avoid per-cpu counter
335          * drift allowing watermarks to be breached
336          */
337         unsigned long percpu_drift_mark;
338 
339         /*
340          * We don't know if the memory that we're going to allocate will be freeable
341          * or/and it will be released eventually, so to avoid totally wasting several
342          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
343          * to run OOM on the lower zones despite there's tons of freeable ram
344          * on the higher zones). This array is recalculated at runtime if the
345          * sysctl_lowmem_reserve_ratio sysctl changes.
346          */
347         unsigned long           lowmem_reserve[MAX_NR_ZONES];
348 
349         /*
350          * This is a per-zone reserve of pages that should not be
351          * considered dirtyable memory.
352          */
353         unsigned long           dirty_balance_reserve;
354 
355 #ifdef CONFIG_NUMA
356         int node;
357         /*
358          * zone reclaim becomes active if more unmapped pages exist.
359          */
360         unsigned long           min_unmapped_pages;
361         unsigned long           min_slab_pages;
362 #endif
363         struct per_cpu_pageset __percpu *pageset;
364         /*
365          * free areas of different sizes
366          */
367         spinlock_t              lock;
368 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
369         /* Set to true when the PG_migrate_skip bits should be cleared */
370         bool                    compact_blockskip_flush;
371 
372         /* pfn where compaction free scanner should start */
373         unsigned long           compact_cached_free_pfn;
374         /* pfn where async and sync compaction migration scanner should start */
375         unsigned long           compact_cached_migrate_pfn[2];
376 #endif
377 #ifdef CONFIG_MEMORY_HOTPLUG
378         /* see spanned/present_pages for more description */
379         seqlock_t               span_seqlock;
380 #endif
381         struct free_area        free_area[MAX_ORDER];
382 
383 #ifndef CONFIG_SPARSEMEM
384         /*
385          * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
386          * In SPARSEMEM, this map is stored in struct mem_section
387          */
388         unsigned long           *pageblock_flags;
389 #endif /* CONFIG_SPARSEMEM */
390 
391 #ifdef CONFIG_COMPACTION
392         /*
393          * On compaction failure, 1<<compact_defer_shift compactions
394          * are skipped before trying again. The number attempted since
395          * last failure is tracked with compact_considered.
396          */
397         unsigned int            compact_considered;
398         unsigned int            compact_defer_shift;
399         int                     compact_order_failed;
400 #endif
401 
402         ZONE_PADDING(_pad1_)
403 
404         /* Fields commonly accessed by the page reclaim scanner */
405         spinlock_t              lru_lock;
406         struct lruvec           lruvec;
407 
408         /* Evictions & activations on the inactive file list */
409         atomic_long_t           inactive_age;
410 
411         unsigned long           pages_scanned;     /* since last reclaim */
412         unsigned long           flags;             /* zone flags, see below */
413 
414         /* Zone statistics */
415         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
416 
417         /*
418          * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
419          * this zone's LRU.  Maintained by the pageout code.
420          */
421         unsigned int inactive_ratio;
422 
423 
424         ZONE_PADDING(_pad2_)
425         /* Rarely used or read-mostly fields */
426 
427         /*
428          * wait_table           -- the array holding the hash table
429          * wait_table_hash_nr_entries   -- the size of the hash table array
430          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
431          *
432          * The purpose of all these is to keep track of the people
433          * waiting for a page to become available and make them
434          * runnable again when possible. The trouble is that this
435          * consumes a lot of space, especially when so few things
436          * wait on pages at a given time. So instead of using
437          * per-page waitqueues, we use a waitqueue hash table.
438          *
439          * The bucket discipline is to sleep on the same queue when
440          * colliding and wake all in that wait queue when removing.
441          * When something wakes, it must check to be sure its page is
442          * truly available, a la thundering herd. The cost of a
443          * collision is great, but given the expected load of the
444          * table, they should be so rare as to be outweighed by the
445          * benefits from the saved space.
446          *
447          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
448          * primary users of these fields, and in mm/page_alloc.c
449          * free_area_init_core() performs the initialization of them.
450          */
451         wait_queue_head_t       * wait_table;
452         unsigned long           wait_table_hash_nr_entries;
453         unsigned long           wait_table_bits;
454 
455         /*
456          * Discontig memory support fields.
457          */
458         struct pglist_data      *zone_pgdat;
459         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
460         unsigned long           zone_start_pfn;
461 
462         /*
463          * spanned_pages is the total pages spanned by the zone, including
464          * holes, which is calculated as:
465          *      spanned_pages = zone_end_pfn - zone_start_pfn;
466          *
467          * present_pages is physical pages existing within the zone, which
468          * is calculated as:
469          *      present_pages = spanned_pages - absent_pages(pages in holes);
470          *
471          * managed_pages is present pages managed by the buddy system, which
472          * is calculated as (reserved_pages includes pages allocated by the
473          * bootmem allocator):
474          *      managed_pages = present_pages - reserved_pages;
475          *
476          * So present_pages may be used by memory hotplug or memory power
477          * management logic to figure out unmanaged pages by checking
478          * (present_pages - managed_pages). And managed_pages should be used
479          * by page allocator and vm scanner to calculate all kinds of watermarks
480          * and thresholds.
481          *
482          * Locking rules:
483          *
484          * zone_start_pfn and spanned_pages are protected by span_seqlock.
485          * It is a seqlock because it has to be read outside of zone->lock,
486          * and it is done in the main allocator path.  But, it is written
487          * quite infrequently.
488          *
489          * The span_seq lock is declared along with zone->lock because it is
490          * frequently read in proximity to zone->lock.  It's good to
491          * give them a chance of being in the same cacheline.
492          *
493          * Write access to present_pages at runtime should be protected by
494          * mem_hotplug_begin/end(). Any reader who can't tolerant drift of
495          * present_pages should get_online_mems() to get a stable value.
496          *
497          * Read access to managed_pages should be safe because it's unsigned
498          * long. Write access to zone->managed_pages and totalram_pages are
499          * protected by managed_page_count_lock at runtime. Idealy only
500          * adjust_managed_page_count() should be used instead of directly
501          * touching zone->managed_pages and totalram_pages.
502          */
503         unsigned long           spanned_pages;
504         unsigned long           present_pages;
505         unsigned long           managed_pages;
506 
507         /*
508          * Number of MIGRATE_RESEVE page block. To maintain for just
509          * optimization. Protected by zone->lock.
510          */
511         int                     nr_migrate_reserve_block;
512 
513         /*
514          * rarely used fields:
515          */
516         const char              *name;
517 } ____cacheline_internodealigned_in_smp;
518 
519 typedef enum {
520         ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
521         ZONE_OOM_LOCKED,                /* zone is in OOM killer zonelist */
522         ZONE_CONGESTED,                 /* zone has many dirty pages backed by
523                                          * a congested BDI
524                                          */
525         ZONE_TAIL_LRU_DIRTY,            /* reclaim scanning has recently found
526                                          * many dirty file pages at the tail
527                                          * of the LRU.
528                                          */
529         ZONE_WRITEBACK,                 /* reclaim scanning has recently found
530                                          * many pages under writeback
531                                          */
532 } zone_flags_t;
533 
534 static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
535 {
536         set_bit(flag, &zone->flags);
537 }
538 
539 static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
540 {
541         return test_and_set_bit(flag, &zone->flags);
542 }
543 
544 static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
545 {
546         clear_bit(flag, &zone->flags);
547 }
548 
549 static inline int zone_is_reclaim_congested(const struct zone *zone)
550 {
551         return test_bit(ZONE_CONGESTED, &zone->flags);
552 }
553 
554 static inline int zone_is_reclaim_dirty(const struct zone *zone)
555 {
556         return test_bit(ZONE_TAIL_LRU_DIRTY, &zone->flags);
557 }
558 
559 static inline int zone_is_reclaim_writeback(const struct zone *zone)
560 {
561         return test_bit(ZONE_WRITEBACK, &zone->flags);
562 }
563 
564 static inline int zone_is_reclaim_locked(const struct zone *zone)
565 {
566         return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
567 }
568 
569 static inline int zone_is_oom_locked(const struct zone *zone)
570 {
571         return test_bit(ZONE_OOM_LOCKED, &zone->flags);
572 }
573 
574 static inline unsigned long zone_end_pfn(const struct zone *zone)
575 {
576         return zone->zone_start_pfn + zone->spanned_pages;
577 }
578 
579 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
580 {
581         return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
582 }
583 
584 static inline bool zone_is_initialized(struct zone *zone)
585 {
586         return !!zone->wait_table;
587 }
588 
589 static inline bool zone_is_empty(struct zone *zone)
590 {
591         return zone->spanned_pages == 0;
592 }
593 
594 /*
595  * The "priority" of VM scanning is how much of the queues we will scan in one
596  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
597  * queues ("queue_length >> 12") during an aging round.
598  */
599 #define DEF_PRIORITY 12
600 
601 /* Maximum number of zones on a zonelist */
602 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
603 
604 #ifdef CONFIG_NUMA
605 
606 /*
607  * The NUMA zonelists are doubled because we need zonelists that restrict the
608  * allocations to a single node for __GFP_THISNODE.
609  *
610  * [0]  : Zonelist with fallback
611  * [1]  : No fallback (__GFP_THISNODE)
612  */
613 #define MAX_ZONELISTS 2
614 
615 
616 /*
617  * We cache key information from each zonelist for smaller cache
618  * footprint when scanning for free pages in get_page_from_freelist().
619  *
620  * 1) The BITMAP fullzones tracks which zones in a zonelist have come
621  *    up short of free memory since the last time (last_fullzone_zap)
622  *    we zero'd fullzones.
623  * 2) The array z_to_n[] maps each zone in the zonelist to its node
624  *    id, so that we can efficiently evaluate whether that node is
625  *    set in the current tasks mems_allowed.
626  *
627  * Both fullzones and z_to_n[] are one-to-one with the zonelist,
628  * indexed by a zones offset in the zonelist zones[] array.
629  *
630  * The get_page_from_freelist() routine does two scans.  During the
631  * first scan, we skip zones whose corresponding bit in 'fullzones'
632  * is set or whose corresponding node in current->mems_allowed (which
633  * comes from cpusets) is not set.  During the second scan, we bypass
634  * this zonelist_cache, to ensure we look methodically at each zone.
635  *
636  * Once per second, we zero out (zap) fullzones, forcing us to
637  * reconsider nodes that might have regained more free memory.
638  * The field last_full_zap is the time we last zapped fullzones.
639  *
640  * This mechanism reduces the amount of time we waste repeatedly
641  * reexaming zones for free memory when they just came up low on
642  * memory momentarilly ago.
643  *
644  * The zonelist_cache struct members logically belong in struct
645  * zonelist.  However, the mempolicy zonelists constructed for
646  * MPOL_BIND are intentionally variable length (and usually much
647  * shorter).  A general purpose mechanism for handling structs with
648  * multiple variable length members is more mechanism than we want
649  * here.  We resort to some special case hackery instead.
650  *
651  * The MPOL_BIND zonelists don't need this zonelist_cache (in good
652  * part because they are shorter), so we put the fixed length stuff
653  * at the front of the zonelist struct, ending in a variable length
654  * zones[], as is needed by MPOL_BIND.
655  *
656  * Then we put the optional zonelist cache on the end of the zonelist
657  * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
658  * the fixed length portion at the front of the struct.  This pointer
659  * both enables us to find the zonelist cache, and in the case of
660  * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
661  * to know that the zonelist cache is not there.
662  *
663  * The end result is that struct zonelists come in two flavors:
664  *  1) The full, fixed length version, shown below, and
665  *  2) The custom zonelists for MPOL_BIND.
666  * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
667  *
668  * Even though there may be multiple CPU cores on a node modifying
669  * fullzones or last_full_zap in the same zonelist_cache at the same
670  * time, we don't lock it.  This is just hint data - if it is wrong now
671  * and then, the allocator will still function, perhaps a bit slower.
672  */
673 
674 
675 struct zonelist_cache {
676         unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];          /* zone->nid */
677         DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);      /* zone full? */
678         unsigned long last_full_zap;            /* when last zap'd (jiffies) */
679 };
680 #else
681 #define MAX_ZONELISTS 1
682 struct zonelist_cache;
683 #endif
684 
685 /*
686  * This struct contains information about a zone in a zonelist. It is stored
687  * here to avoid dereferences into large structures and lookups of tables
688  */
689 struct zoneref {
690         struct zone *zone;      /* Pointer to actual zone */
691         int zone_idx;           /* zone_idx(zoneref->zone) */
692 };
693 
694 /*
695  * One allocation request operates on a zonelist. A zonelist
696  * is a list of zones, the first one is the 'goal' of the
697  * allocation, the other zones are fallback zones, in decreasing
698  * priority.
699  *
700  * If zlcache_ptr is not NULL, then it is just the address of zlcache,
701  * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
702  * *
703  * To speed the reading of the zonelist, the zonerefs contain the zone index
704  * of the entry being read. Helper functions to access information given
705  * a struct zoneref are
706  *
707  * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
708  * zonelist_zone_idx()  - Return the index of the zone for an entry
709  * zonelist_node_idx()  - Return the index of the node for an entry
710  */
711 struct zonelist {
712         struct zonelist_cache *zlcache_ptr;                  // NULL or &zlcache
713         struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
714 #ifdef CONFIG_NUMA
715         struct zonelist_cache zlcache;                       // optional ...
716 #endif
717 };
718 
719 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
720 struct node_active_region {
721         unsigned long start_pfn;
722         unsigned long end_pfn;
723         int nid;
724 };
725 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
726 
727 #ifndef CONFIG_DISCONTIGMEM
728 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
729 extern struct page *mem_map;
730 #endif
731 
732 /*
733  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
734  * (mostly NUMA machines?) to denote a higher-level memory zone than the
735  * zone denotes.
736  *
737  * On NUMA machines, each NUMA node would have a pg_data_t to describe
738  * it's memory layout.
739  *
740  * Memory statistics and page replacement data structures are maintained on a
741  * per-zone basis.
742  */
743 struct bootmem_data;
744 typedef struct pglist_data {
745         struct zone node_zones[MAX_NR_ZONES];
746         struct zonelist node_zonelists[MAX_ZONELISTS];
747         int nr_zones;
748 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
749         struct page *node_mem_map;
750 #ifdef CONFIG_MEMCG
751         struct page_cgroup *node_page_cgroup;
752 #endif
753 #endif
754 #ifndef CONFIG_NO_BOOTMEM
755         struct bootmem_data *bdata;
756 #endif
757 #ifdef CONFIG_MEMORY_HOTPLUG
758         /*
759          * Must be held any time you expect node_start_pfn, node_present_pages
760          * or node_spanned_pages stay constant.  Holding this will also
761          * guarantee that any pfn_valid() stays that way.
762          *
763          * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
764          * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG.
765          *
766          * Nests above zone->lock and zone->span_seqlock
767          */
768         spinlock_t node_size_lock;
769 #endif
770         unsigned long node_start_pfn;
771         unsigned long node_present_pages; /* total number of physical pages */
772         unsigned long node_spanned_pages; /* total size of physical page
773                                              range, including holes */
774         int node_id;
775         wait_queue_head_t kswapd_wait;
776         wait_queue_head_t pfmemalloc_wait;
777         struct task_struct *kswapd;     /* Protected by
778                                            mem_hotplug_begin/end() */
779         int kswapd_max_order;
780         enum zone_type classzone_idx;
781 #ifdef CONFIG_NUMA_BALANCING
782         /* Lock serializing the migrate rate limiting window */
783         spinlock_t numabalancing_migrate_lock;
784 
785         /* Rate limiting time interval */
786         unsigned long numabalancing_migrate_next_window;
787 
788         /* Number of pages migrated during the rate limiting time interval */
789         unsigned long numabalancing_migrate_nr_pages;
790 #endif
791 } pg_data_t;
792 
793 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
794 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
795 #ifdef CONFIG_FLAT_NODE_MEM_MAP
796 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
797 #else
798 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
799 #endif
800 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
801 
802 #define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
803 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
804 
805 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
806 {
807         return pgdat->node_start_pfn + pgdat->node_spanned_pages;
808 }
809 
810 static inline bool pgdat_is_empty(pg_data_t *pgdat)
811 {
812         return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
813 }
814 
815 #include <linux/memory_hotplug.h>
816 
817 extern struct mutex zonelists_mutex;
818 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
819 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
820 bool zone_watermark_ok(struct zone *z, unsigned int order,
821                 unsigned long mark, int classzone_idx, int alloc_flags);
822 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
823                 unsigned long mark, int classzone_idx, int alloc_flags);
824 enum memmap_context {
825         MEMMAP_EARLY,
826         MEMMAP_HOTPLUG,
827 };
828 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
829                                      unsigned long size,
830                                      enum memmap_context context);
831 
832 extern void lruvec_init(struct lruvec *lruvec);
833 
834 static inline struct zone *lruvec_zone(struct lruvec *lruvec)
835 {
836 #ifdef CONFIG_MEMCG
837         return lruvec->zone;
838 #else
839         return container_of(lruvec, struct zone, lruvec);
840 #endif
841 }
842 
843 #ifdef CONFIG_HAVE_MEMORY_PRESENT
844 void memory_present(int nid, unsigned long start, unsigned long end);
845 #else
846 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
847 #endif
848 
849 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
850 int local_memory_node(int node_id);
851 #else
852 static inline int local_memory_node(int node_id) { return node_id; };
853 #endif
854 
855 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
856 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
857 #endif
858 
859 /*
860  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
861  */
862 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
863 
864 static inline int populated_zone(struct zone *zone)
865 {
866         return (!!zone->present_pages);
867 }
868 
869 extern int movable_zone;
870 
871 static inline int zone_movable_is_highmem(void)
872 {
873 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
874         return movable_zone == ZONE_HIGHMEM;
875 #else
876         return 0;
877 #endif
878 }
879 
880 static inline int is_highmem_idx(enum zone_type idx)
881 {
882 #ifdef CONFIG_HIGHMEM
883         return (idx == ZONE_HIGHMEM ||
884                 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
885 #else
886         return 0;
887 #endif
888 }
889 
890 /**
891  * is_highmem - helper function to quickly check if a struct zone is a 
892  *              highmem zone or not.  This is an attempt to keep references
893  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
894  * @zone - pointer to struct zone variable
895  */
896 static inline int is_highmem(struct zone *zone)
897 {
898 #ifdef CONFIG_HIGHMEM
899         int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
900         return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
901                (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
902                 zone_movable_is_highmem());
903 #else
904         return 0;
905 #endif
906 }
907 
908 /* These two functions are used to setup the per zone pages min values */
909 struct ctl_table;
910 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
911                                         void __user *, size_t *, loff_t *);
912 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
913 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
914                                         void __user *, size_t *, loff_t *);
915 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
916                                         void __user *, size_t *, loff_t *);
917 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
918                         void __user *, size_t *, loff_t *);
919 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
920                         void __user *, size_t *, loff_t *);
921 
922 extern int numa_zonelist_order_handler(struct ctl_table *, int,
923                         void __user *, size_t *, loff_t *);
924 extern char numa_zonelist_order[];
925 #define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
926 
927 #ifndef CONFIG_NEED_MULTIPLE_NODES
928 
929 extern struct pglist_data contig_page_data;
930 #define NODE_DATA(nid)          (&contig_page_data)
931 #define NODE_MEM_MAP(nid)       mem_map
932 
933 #else /* CONFIG_NEED_MULTIPLE_NODES */
934 
935 #include <asm/mmzone.h>
936 
937 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
938 
939 extern struct pglist_data *first_online_pgdat(void);
940 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
941 extern struct zone *next_zone(struct zone *zone);
942 
943 /**
944  * for_each_online_pgdat - helper macro to iterate over all online nodes
945  * @pgdat - pointer to a pg_data_t variable
946  */
947 #define for_each_online_pgdat(pgdat)                    \
948         for (pgdat = first_online_pgdat();              \
949              pgdat;                                     \
950              pgdat = next_online_pgdat(pgdat))
951 /**
952  * for_each_zone - helper macro to iterate over all memory zones
953  * @zone - pointer to struct zone variable
954  *
955  * The user only needs to declare the zone variable, for_each_zone
956  * fills it in.
957  */
958 #define for_each_zone(zone)                             \
959         for (zone = (first_online_pgdat())->node_zones; \
960              zone;                                      \
961              zone = next_zone(zone))
962 
963 #define for_each_populated_zone(zone)                   \
964         for (zone = (first_online_pgdat())->node_zones; \
965              zone;                                      \
966              zone = next_zone(zone))                    \
967                 if (!populated_zone(zone))              \
968                         ; /* do nothing */              \
969                 else
970 
971 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
972 {
973         return zoneref->zone;
974 }
975 
976 static inline int zonelist_zone_idx(struct zoneref *zoneref)
977 {
978         return zoneref->zone_idx;
979 }
980 
981 static inline int zonelist_node_idx(struct zoneref *zoneref)
982 {
983 #ifdef CONFIG_NUMA
984         /* zone_to_nid not available in this context */
985         return zoneref->zone->node;
986 #else
987         return 0;
988 #endif /* CONFIG_NUMA */
989 }
990 
991 /**
992  * 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
993  * @z - The cursor used as a starting point for the search
994  * @highest_zoneidx - The zone index of the highest zone to return
995  * @nodes - An optional nodemask to filter the zonelist with
996  * @zone - The first suitable zone found is returned via this parameter
997  *
998  * This function returns the next zone at or below a given zone index that is
999  * within the allowed nodemask using a cursor as the starting point for the
1000  * search. The zoneref returned is a cursor that represents the current zone
1001  * being examined. It should be advanced by one before calling
1002  * next_zones_zonelist again.
1003  */
1004 struct zoneref *next_zones_zonelist(struct zoneref *z,
1005                                         enum zone_type highest_zoneidx,
1006                                         nodemask_t *nodes,
1007                                         struct zone **zone);
1008 
1009 /**
1010  * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
1011  * @zonelist - The zonelist to search for a suitable zone
1012  * @highest_zoneidx - The zone index of the highest zone to return
1013  * @nodes - An optional nodemask to filter the zonelist with
1014  * @zone - The first suitable zone found is returned via this parameter
1015  *
1016  * This function returns the first zone at or below a given zone index that is
1017  * within the allowed nodemask. The zoneref returned is a cursor that can be
1018  * used to iterate the zonelist with next_zones_zonelist by advancing it by
1019  * one before calling.
1020  */
1021 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
1022                                         enum zone_type highest_zoneidx,
1023                                         nodemask_t *nodes,
1024                                         struct zone **zone)
1025 {
1026         return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
1027                                                                 zone);
1028 }
1029 
1030 /**
1031  * 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
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  * @nodemask - Nodemask allowed by the allocator
1037  *
1038  * This iterator iterates though all zones at or below a given zone index and
1039  * within a given nodemask
1040  */
1041 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1042         for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
1043                 zone;                                                   \
1044                 z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
1045 
1046 /**
1047  * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1048  * @zone - The current zone in the iterator
1049  * @z - The current pointer within zonelist->zones being iterated
1050  * @zlist - The zonelist being iterated
1051  * @highidx - The zone index of the highest zone to return
1052  *
1053  * This iterator iterates though all zones at or below a given zone index.
1054  */
1055 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1056         for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1057 
1058 #ifdef CONFIG_SPARSEMEM
1059 #include <asm/sparsemem.h>
1060 #endif
1061 
1062 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1063         !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1064 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1065 {
1066         return 0;
1067 }
1068 #endif
1069 
1070 #ifdef CONFIG_FLATMEM
1071 #define pfn_to_nid(pfn)         (0)
1072 #endif
1073 
1074 #ifdef CONFIG_SPARSEMEM
1075 
1076 /*
1077  * SECTION_SHIFT                #bits space required to store a section #
1078  *
1079  * PA_SECTION_SHIFT             physical address to/from section number
1080  * PFN_SECTION_SHIFT            pfn to/from section number
1081  */
1082 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1083 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1084 
1085 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1086 
1087 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1088 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1089 
1090 #define SECTION_BLOCKFLAGS_BITS \
1091         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1092 
1093 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1094 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1095 #endif
1096 
1097 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1098 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1099 
1100 #define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1101 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1102 
1103 struct page;
1104 struct page_cgroup;
1105 struct mem_section {
1106         /*
1107          * This is, logically, a pointer to an array of struct
1108          * pages.  However, it is stored with some other magic.
1109          * (see sparse.c::sparse_init_one_section())
1110          *
1111          * Additionally during early boot we encode node id of
1112          * the location of the section here to guide allocation.
1113          * (see sparse.c::memory_present())
1114          *
1115          * Making it a UL at least makes someone do a cast
1116          * before using it wrong.
1117          */
1118         unsigned long section_mem_map;
1119 
1120         /* See declaration of similar field in struct zone */
1121         unsigned long *pageblock_flags;
1122 #ifdef CONFIG_MEMCG
1123         /*
1124          * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1125          * section. (see memcontrol.h/page_cgroup.h about this.)
1126          */
1127         struct page_cgroup *page_cgroup;
1128         unsigned long pad;
1129 #endif
1130         /*
1131          * WARNING: mem_section must be a power-of-2 in size for the
1132          * calculation and use of SECTION_ROOT_MASK to make sense.
1133          */
1134 };
1135 
1136 #ifdef CONFIG_SPARSEMEM_EXTREME
1137 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1138 #else
1139 #define SECTIONS_PER_ROOT       1
1140 #endif
1141 
1142 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1143 #define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1144 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1145 
1146 #ifdef CONFIG_SPARSEMEM_EXTREME
1147 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1148 #else
1149 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1150 #endif
1151 
1152 static inline struct mem_section *__nr_to_section(unsigned long nr)
1153 {
1154         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1155                 return NULL;
1156         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1157 }
1158 extern int __section_nr(struct mem_section* ms);
1159 extern unsigned long usemap_size(void);
1160 
1161 /*
1162  * We use the lower bits of the mem_map pointer to store
1163  * a little bit of information.  There should be at least
1164  * 3 bits here due to 32-bit alignment.
1165  */
1166 #define SECTION_MARKED_PRESENT  (1UL<<0)
1167 #define SECTION_HAS_MEM_MAP     (1UL<<1)
1168 #define SECTION_MAP_LAST_BIT    (1UL<<2)
1169 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1170 #define SECTION_NID_SHIFT       2
1171 
1172 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1173 {
1174         unsigned long map = section->section_mem_map;
1175         map &= SECTION_MAP_MASK;
1176         return (struct page *)map;
1177 }
1178 
1179 static inline int present_section(struct mem_section *section)
1180 {
1181         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1182 }
1183 
1184 static inline int present_section_nr(unsigned long nr)
1185 {
1186         return present_section(__nr_to_section(nr));
1187 }
1188 
1189 static inline int valid_section(struct mem_section *section)
1190 {
1191         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1192 }
1193 
1194 static inline int valid_section_nr(unsigned long nr)
1195 {
1196         return valid_section(__nr_to_section(nr));
1197 }
1198 
1199 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1200 {
1201         return __nr_to_section(pfn_to_section_nr(pfn));
1202 }
1203 
1204 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1205 static inline int pfn_valid(unsigned long pfn)
1206 {
1207         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1208                 return 0;
1209         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1210 }
1211 #endif
1212 
1213 static inline int pfn_present(unsigned long pfn)
1214 {
1215         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1216                 return 0;
1217         return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1218 }
1219 
1220 /*
1221  * These are _only_ used during initialisation, therefore they
1222  * can use __initdata ...  They could have names to indicate
1223  * this restriction.
1224  */
1225 #ifdef CONFIG_NUMA
1226 #define pfn_to_nid(pfn)                                                 \
1227 ({                                                                      \
1228         unsigned long __pfn_to_nid_pfn = (pfn);                         \
1229         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1230 })
1231 #else
1232 #define pfn_to_nid(pfn)         (0)
1233 #endif
1234 
1235 #define early_pfn_valid(pfn)    pfn_valid(pfn)
1236 void sparse_init(void);
1237 #else
1238 #define sparse_init()   do {} while (0)
1239 #define sparse_index_init(_sec, _nid)  do {} while (0)
1240 #endif /* CONFIG_SPARSEMEM */
1241 
1242 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
1243 bool early_pfn_in_nid(unsigned long pfn, int nid);
1244 #else
1245 #define early_pfn_in_nid(pfn, nid)      (1)
1246 #endif
1247 
1248 #ifndef early_pfn_valid
1249 #define early_pfn_valid(pfn)    (1)
1250 #endif
1251 
1252 void memory_present(int nid, unsigned long start, unsigned long end);
1253 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1254 
1255 /*
1256  * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1257  * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1258  * pfn_valid_within() should be used in this case; we optimise this away
1259  * when we have no holes within a MAX_ORDER_NR_PAGES block.
1260  */
1261 #ifdef CONFIG_HOLES_IN_ZONE
1262 #define pfn_valid_within(pfn) pfn_valid(pfn)
1263 #else
1264 #define pfn_valid_within(pfn) (1)
1265 #endif
1266 
1267 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1268 /*
1269  * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1270  * associated with it or not. In FLATMEM, it is expected that holes always
1271  * have valid memmap as long as there is valid PFNs either side of the hole.
1272  * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1273  * entire section.
1274  *
1275  * However, an ARM, and maybe other embedded architectures in the future
1276  * free memmap backing holes to save memory on the assumption the memmap is
1277  * never used. The page_zone linkages are then broken even though pfn_valid()
1278  * returns true. A walker of the full memmap must then do this additional
1279  * check to ensure the memmap they are looking at is sane by making sure
1280  * the zone and PFN linkages are still valid. This is expensive, but walkers
1281  * of the full memmap are extremely rare.
1282  */
1283 int memmap_valid_within(unsigned long pfn,
1284                                         struct page *page, struct zone *zone);
1285 #else
1286 static inline int memmap_valid_within(unsigned long pfn,
1287                                         struct page *page, struct zone *zone)
1288 {
1289         return 1;
1290 }
1291 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1292 
1293 #endif /* !__GENERATING_BOUNDS.H */
1294 #endif /* !__ASSEMBLY__ */
1295 #endif /* _LINUX_MMZONE_H */
1296 

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