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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 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_ALLOC_BATCH,
109         NR_LRU_BASE,
110         NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
111         NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
112         NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
113         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
114         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
115         NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
116         NR_ANON_PAGES,  /* Mapped anonymous pages */
117         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
118                            only modified from process context */
119         NR_FILE_PAGES,
120         NR_FILE_DIRTY,
121         NR_WRITEBACK,
122         NR_SLAB_RECLAIMABLE,
123         NR_SLAB_UNRECLAIMABLE,
124         NR_PAGETABLE,           /* used for pagetables */
125         NR_KERNEL_STACK,
126         /* Second 128 byte cacheline */
127         NR_UNSTABLE_NFS,        /* NFS unstable pages */
128         NR_BOUNCE,
129         NR_VMSCAN_WRITE,
130         NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
131         NR_WRITEBACK_TEMP,      /* Writeback using temporary buffers */
132         NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
133         NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
134         NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
135         NR_DIRTIED,             /* page dirtyings since bootup */
136         NR_WRITTEN,             /* page writings since bootup */
137 #ifdef CONFIG_NUMA
138         NUMA_HIT,               /* allocated in intended node */
139         NUMA_MISS,              /* allocated in non intended node */
140         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
141         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
142         NUMA_LOCAL,             /* allocation from local node */
143         NUMA_OTHER,             /* allocation from other node */
144 #endif
145         NR_ANON_TRANSPARENT_HUGEPAGES,
146         NR_FREE_CMA_PAGES,
147         NR_VM_ZONE_STAT_ITEMS };
148 
149 /*
150  * We do arithmetic on the LRU lists in various places in the code,
151  * so it is important to keep the active lists LRU_ACTIVE higher in
152  * the array than the corresponding inactive lists, and to keep
153  * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
154  *
155  * This has to be kept in sync with the statistics in zone_stat_item
156  * above and the descriptions in vmstat_text in mm/vmstat.c
157  */
158 #define LRU_BASE 0
159 #define LRU_ACTIVE 1
160 #define LRU_FILE 2
161 
162 enum lru_list {
163         LRU_INACTIVE_ANON = LRU_BASE,
164         LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
165         LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
166         LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
167         LRU_UNEVICTABLE,
168         NR_LRU_LISTS
169 };
170 
171 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
172 
173 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
174 
175 static inline int is_file_lru(enum lru_list lru)
176 {
177         return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
178 }
179 
180 static inline int is_active_lru(enum lru_list lru)
181 {
182         return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
183 }
184 
185 static inline int is_unevictable_lru(enum lru_list lru)
186 {
187         return (lru == LRU_UNEVICTABLE);
188 }
189 
190 struct zone_reclaim_stat {
191         /*
192          * The pageout code in vmscan.c keeps track of how many of the
193          * mem/swap backed and file backed pages are referenced.
194          * The higher the rotated/scanned ratio, the more valuable
195          * that cache is.
196          *
197          * The anon LRU stats live in [0], file LRU stats in [1]
198          */
199         unsigned long           recent_rotated[2];
200         unsigned long           recent_scanned[2];
201 };
202 
203 struct lruvec {
204         struct list_head lists[NR_LRU_LISTS];
205         struct zone_reclaim_stat reclaim_stat;
206 #ifdef CONFIG_MEMCG
207         struct zone *zone;
208 #endif
209 };
210 
211 /* Mask used at gathering information at once (see memcontrol.c) */
212 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
213 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
214 #define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
215 
216 /* Isolate clean file */
217 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
218 /* Isolate unmapped file */
219 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
220 /* Isolate for asynchronous migration */
221 #define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
222 /* Isolate unevictable pages */
223 #define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
224 
225 /* LRU Isolation modes. */
226 typedef unsigned __bitwise__ isolate_mode_t;
227 
228 enum zone_watermarks {
229         WMARK_MIN,
230         WMARK_LOW,
231         WMARK_HIGH,
232         NR_WMARK
233 };
234 
235 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
236 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
237 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
238 
239 struct per_cpu_pages {
240         int count;              /* number of pages in the list */
241         int high;               /* high watermark, emptying needed */
242         int batch;              /* chunk size for buddy add/remove */
243 
244         /* Lists of pages, one per migrate type stored on the pcp-lists */
245         struct list_head lists[MIGRATE_PCPTYPES];
246 };
247 
248 struct per_cpu_pageset {
249         struct per_cpu_pages pcp;
250 #ifdef CONFIG_NUMA
251         s8 expire;
252 #endif
253 #ifdef CONFIG_SMP
254         s8 stat_threshold;
255         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
256 #endif
257 };
258 
259 #endif /* !__GENERATING_BOUNDS.H */
260 
261 enum zone_type {
262 #ifdef CONFIG_ZONE_DMA
263         /*
264          * ZONE_DMA is used when there are devices that are not able
265          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
266          * carve out the portion of memory that is needed for these devices.
267          * The range is arch specific.
268          *
269          * Some examples
270          *
271          * Architecture         Limit
272          * ---------------------------
273          * parisc, ia64, sparc  <4G
274          * s390                 <2G
275          * arm                  Various
276          * alpha                Unlimited or 0-16MB.
277          *
278          * i386, x86_64 and multiple other arches
279          *                      <16M.
280          */
281         ZONE_DMA,
282 #endif
283 #ifdef CONFIG_ZONE_DMA32
284         /*
285          * x86_64 needs two ZONE_DMAs because it supports devices that are
286          * only able to do DMA to the lower 16M but also 32 bit devices that
287          * can only do DMA areas below 4G.
288          */
289         ZONE_DMA32,
290 #endif
291         /*
292          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
293          * performed on pages in ZONE_NORMAL if the DMA devices support
294          * transfers to all addressable memory.
295          */
296         ZONE_NORMAL,
297 #ifdef CONFIG_HIGHMEM
298         /*
299          * A memory area that is only addressable by the kernel through
300          * mapping portions into its own address space. This is for example
301          * used by i386 to allow the kernel to address the memory beyond
302          * 900MB. The kernel will set up special mappings (page
303          * table entries on i386) for each page that the kernel needs to
304          * access.
305          */
306         ZONE_HIGHMEM,
307 #endif
308         ZONE_MOVABLE,
309         __MAX_NR_ZONES
310 };
311 
312 #ifndef __GENERATING_BOUNDS_H
313 
314 struct zone {
315         /* Fields commonly accessed by the page allocator */
316 
317         /* zone watermarks, access with *_wmark_pages(zone) macros */
318         unsigned long watermark[NR_WMARK];
319 
320         /*
321          * When free pages are below this point, additional steps are taken
322          * when reading the number of free pages to avoid per-cpu counter
323          * drift allowing watermarks to be breached
324          */
325         unsigned long percpu_drift_mark;
326 
327         /*
328          * We don't know if the memory that we're going to allocate will be freeable
329          * or/and it will be released eventually, so to avoid totally wasting several
330          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
331          * to run OOM on the lower zones despite there's tons of freeable ram
332          * on the higher zones). This array is recalculated at runtime if the
333          * sysctl_lowmem_reserve_ratio sysctl changes.
334          */
335         unsigned long           lowmem_reserve[MAX_NR_ZONES];
336 
337         /*
338          * This is a per-zone reserve of pages that should not be
339          * considered dirtyable memory.
340          */
341         unsigned long           dirty_balance_reserve;
342 
343 #ifdef CONFIG_NUMA
344         int node;
345         /*
346          * zone reclaim becomes active if more unmapped pages exist.
347          */
348         unsigned long           min_unmapped_pages;
349         unsigned long           min_slab_pages;
350 #endif
351         struct per_cpu_pageset __percpu *pageset;
352         /*
353          * free areas of different sizes
354          */
355         spinlock_t              lock;
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 at runtime should be protected by
478          * lock_memory_hotplug()/unlock_memory_hotplug().  Any reader who can't
479          * tolerant drift of present_pages should hold memory hotplug lock to
480          * get a stable value.
481          *
482          * Read access to managed_pages should be safe because it's unsigned
483          * long. Write access to zone->managed_pages and totalram_pages are
484          * protected by managed_page_count_lock at runtime. Idealy only
485          * adjust_managed_page_count() should be used instead of directly
486          * touching zone->managed_pages and totalram_pages.
487          */
488         unsigned long           spanned_pages;
489         unsigned long           present_pages;
490         unsigned long           managed_pages;
491 
492         /*
493          * Number of MIGRATE_RESEVE page block. To maintain for just
494          * optimization. Protected by zone->lock.
495          */
496         int                     nr_migrate_reserve_block;
497 
498         /*
499          * rarely used fields:
500          */
501         const char              *name;
502 } ____cacheline_internodealigned_in_smp;
503 
504 typedef enum {
505         ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
506         ZONE_OOM_LOCKED,                /* zone is in OOM killer zonelist */
507         ZONE_CONGESTED,                 /* zone has many dirty pages backed by
508                                          * a congested BDI
509                                          */
510         ZONE_TAIL_LRU_DIRTY,            /* reclaim scanning has recently found
511                                          * many dirty file pages at the tail
512                                          * of the LRU.
513                                          */
514         ZONE_WRITEBACK,                 /* reclaim scanning has recently found
515                                          * many pages under writeback
516                                          */
517 } zone_flags_t;
518 
519 static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
520 {
521         set_bit(flag, &zone->flags);
522 }
523 
524 static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
525 {
526         return test_and_set_bit(flag, &zone->flags);
527 }
528 
529 static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
530 {
531         clear_bit(flag, &zone->flags);
532 }
533 
534 static inline int zone_is_reclaim_congested(const struct zone *zone)
535 {
536         return test_bit(ZONE_CONGESTED, &zone->flags);
537 }
538 
539 static inline int zone_is_reclaim_dirty(const struct zone *zone)
540 {
541         return test_bit(ZONE_TAIL_LRU_DIRTY, &zone->flags);
542 }
543 
544 static inline int zone_is_reclaim_writeback(const struct zone *zone)
545 {
546         return test_bit(ZONE_WRITEBACK, &zone->flags);
547 }
548 
549 static inline int zone_is_reclaim_locked(const struct zone *zone)
550 {
551         return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
552 }
553 
554 static inline int zone_is_oom_locked(const struct zone *zone)
555 {
556         return test_bit(ZONE_OOM_LOCKED, &zone->flags);
557 }
558 
559 static inline unsigned long zone_end_pfn(const struct zone *zone)
560 {
561         return zone->zone_start_pfn + zone->spanned_pages;
562 }
563 
564 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
565 {
566         return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
567 }
568 
569 static inline bool zone_is_initialized(struct zone *zone)
570 {
571         return !!zone->wait_table;
572 }
573 
574 static inline bool zone_is_empty(struct zone *zone)
575 {
576         return zone->spanned_pages == 0;
577 }
578 
579 /*
580  * The "priority" of VM scanning is how much of the queues we will scan in one
581  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
582  * queues ("queue_length >> 12") during an aging round.
583  */
584 #define DEF_PRIORITY 12
585 
586 /* Maximum number of zones on a zonelist */
587 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
588 
589 #ifdef CONFIG_NUMA
590 
591 /*
592  * The NUMA zonelists are doubled because we need zonelists that restrict the
593  * allocations to a single node for __GFP_THISNODE.
594  *
595  * [0]  : Zonelist with fallback
596  * [1]  : No fallback (__GFP_THISNODE)
597  */
598 #define MAX_ZONELISTS 2
599 
600 
601 /*
602  * We cache key information from each zonelist for smaller cache
603  * footprint when scanning for free pages in get_page_from_freelist().
604  *
605  * 1) The BITMAP fullzones tracks which zones in a zonelist have come
606  *    up short of free memory since the last time (last_fullzone_zap)
607  *    we zero'd fullzones.
608  * 2) The array z_to_n[] maps each zone in the zonelist to its node
609  *    id, so that we can efficiently evaluate whether that node is
610  *    set in the current tasks mems_allowed.
611  *
612  * Both fullzones and z_to_n[] are one-to-one with the zonelist,
613  * indexed by a zones offset in the zonelist zones[] array.
614  *
615  * The get_page_from_freelist() routine does two scans.  During the
616  * first scan, we skip zones whose corresponding bit in 'fullzones'
617  * is set or whose corresponding node in current->mems_allowed (which
618  * comes from cpusets) is not set.  During the second scan, we bypass
619  * this zonelist_cache, to ensure we look methodically at each zone.
620  *
621  * Once per second, we zero out (zap) fullzones, forcing us to
622  * reconsider nodes that might have regained more free memory.
623  * The field last_full_zap is the time we last zapped fullzones.
624  *
625  * This mechanism reduces the amount of time we waste repeatedly
626  * reexaming zones for free memory when they just came up low on
627  * memory momentarilly ago.
628  *
629  * The zonelist_cache struct members logically belong in struct
630  * zonelist.  However, the mempolicy zonelists constructed for
631  * MPOL_BIND are intentionally variable length (and usually much
632  * shorter).  A general purpose mechanism for handling structs with
633  * multiple variable length members is more mechanism than we want
634  * here.  We resort to some special case hackery instead.
635  *
636  * The MPOL_BIND zonelists don't need this zonelist_cache (in good
637  * part because they are shorter), so we put the fixed length stuff
638  * at the front of the zonelist struct, ending in a variable length
639  * zones[], as is needed by MPOL_BIND.
640  *
641  * Then we put the optional zonelist cache on the end of the zonelist
642  * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
643  * the fixed length portion at the front of the struct.  This pointer
644  * both enables us to find the zonelist cache, and in the case of
645  * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
646  * to know that the zonelist cache is not there.
647  *
648  * The end result is that struct zonelists come in two flavors:
649  *  1) The full, fixed length version, shown below, and
650  *  2) The custom zonelists for MPOL_BIND.
651  * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
652  *
653  * Even though there may be multiple CPU cores on a node modifying
654  * fullzones or last_full_zap in the same zonelist_cache at the same
655  * time, we don't lock it.  This is just hint data - if it is wrong now
656  * and then, the allocator will still function, perhaps a bit slower.
657  */
658 
659 
660 struct zonelist_cache {
661         unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];          /* zone->nid */
662         DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);      /* zone full? */
663         unsigned long last_full_zap;            /* when last zap'd (jiffies) */
664 };
665 #else
666 #define MAX_ZONELISTS 1
667 struct zonelist_cache;
668 #endif
669 
670 /*
671  * This struct contains information about a zone in a zonelist. It is stored
672  * here to avoid dereferences into large structures and lookups of tables
673  */
674 struct zoneref {
675         struct zone *zone;      /* Pointer to actual zone */
676         int zone_idx;           /* zone_idx(zoneref->zone) */
677 };
678 
679 /*
680  * One allocation request operates on a zonelist. A zonelist
681  * is a list of zones, the first one is the 'goal' of the
682  * allocation, the other zones are fallback zones, in decreasing
683  * priority.
684  *
685  * If zlcache_ptr is not NULL, then it is just the address of zlcache,
686  * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
687  * *
688  * To speed the reading of the zonelist, the zonerefs contain the zone index
689  * of the entry being read. Helper functions to access information given
690  * a struct zoneref are
691  *
692  * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
693  * zonelist_zone_idx()  - Return the index of the zone for an entry
694  * zonelist_node_idx()  - Return the index of the node for an entry
695  */
696 struct zonelist {
697         struct zonelist_cache *zlcache_ptr;                  // NULL or &zlcache
698         struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
699 #ifdef CONFIG_NUMA
700         struct zonelist_cache zlcache;                       // optional ...
701 #endif
702 };
703 
704 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
705 struct node_active_region {
706         unsigned long start_pfn;
707         unsigned long end_pfn;
708         int nid;
709 };
710 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
711 
712 #ifndef CONFIG_DISCONTIGMEM
713 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
714 extern struct page *mem_map;
715 #endif
716 
717 /*
718  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
719  * (mostly NUMA machines?) to denote a higher-level memory zone than the
720  * zone denotes.
721  *
722  * On NUMA machines, each NUMA node would have a pg_data_t to describe
723  * it's memory layout.
724  *
725  * Memory statistics and page replacement data structures are maintained on a
726  * per-zone basis.
727  */
728 struct bootmem_data;
729 typedef struct pglist_data {
730         struct zone node_zones[MAX_NR_ZONES];
731         struct zonelist node_zonelists[MAX_ZONELISTS];
732         int nr_zones;
733 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
734         struct page *node_mem_map;
735 #ifdef CONFIG_MEMCG
736         struct page_cgroup *node_page_cgroup;
737 #endif
738 #endif
739 #ifndef CONFIG_NO_BOOTMEM
740         struct bootmem_data *bdata;
741 #endif
742 #ifdef CONFIG_MEMORY_HOTPLUG
743         /*
744          * Must be held any time you expect node_start_pfn, node_present_pages
745          * or node_spanned_pages stay constant.  Holding this will also
746          * guarantee that any pfn_valid() stays that way.
747          *
748          * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
749          * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG.
750          *
751          * Nests above zone->lock and zone->span_seqlock
752          */
753         spinlock_t node_size_lock;
754 #endif
755         unsigned long node_start_pfn;
756         unsigned long node_present_pages; /* total number of physical pages */
757         unsigned long node_spanned_pages; /* total size of physical page
758                                              range, including holes */
759         int node_id;
760         nodemask_t reclaim_nodes;       /* Nodes allowed to reclaim from */
761         wait_queue_head_t kswapd_wait;
762         wait_queue_head_t pfmemalloc_wait;
763         struct task_struct *kswapd;     /* Protected by lock_memory_hotplug() */
764         int kswapd_max_order;
765         enum zone_type classzone_idx;
766 #ifdef CONFIG_NUMA_BALANCING
767         /* Lock serializing the migrate rate limiting window */
768         spinlock_t numabalancing_migrate_lock;
769 
770         /* Rate limiting time interval */
771         unsigned long numabalancing_migrate_next_window;
772 
773         /* Number of pages migrated during the rate limiting time interval */
774         unsigned long numabalancing_migrate_nr_pages;
775 #endif
776 } pg_data_t;
777 
778 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
779 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
780 #ifdef CONFIG_FLAT_NODE_MEM_MAP
781 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
782 #else
783 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
784 #endif
785 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
786 
787 #define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
788 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
789 
790 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
791 {
792         return pgdat->node_start_pfn + pgdat->node_spanned_pages;
793 }
794 
795 static inline bool pgdat_is_empty(pg_data_t *pgdat)
796 {
797         return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
798 }
799 
800 #include <linux/memory_hotplug.h>
801 
802 extern struct mutex zonelists_mutex;
803 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
804 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
805 bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
806                 int classzone_idx, int alloc_flags);
807 bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
808                 int classzone_idx, int alloc_flags);
809 enum memmap_context {
810         MEMMAP_EARLY,
811         MEMMAP_HOTPLUG,
812 };
813 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
814                                      unsigned long size,
815                                      enum memmap_context context);
816 
817 extern void lruvec_init(struct lruvec *lruvec);
818 
819 static inline struct zone *lruvec_zone(struct lruvec *lruvec)
820 {
821 #ifdef CONFIG_MEMCG
822         return lruvec->zone;
823 #else
824         return container_of(lruvec, struct zone, lruvec);
825 #endif
826 }
827 
828 #ifdef CONFIG_HAVE_MEMORY_PRESENT
829 void memory_present(int nid, unsigned long start, unsigned long end);
830 #else
831 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
832 #endif
833 
834 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
835 int local_memory_node(int node_id);
836 #else
837 static inline int local_memory_node(int node_id) { return node_id; };
838 #endif
839 
840 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
841 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
842 #endif
843 
844 /*
845  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
846  */
847 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
848 
849 static inline int populated_zone(struct zone *zone)
850 {
851         return (!!zone->present_pages);
852 }
853 
854 extern int movable_zone;
855 
856 static inline int zone_movable_is_highmem(void)
857 {
858 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
859         return movable_zone == ZONE_HIGHMEM;
860 #else
861         return 0;
862 #endif
863 }
864 
865 static inline int is_highmem_idx(enum zone_type idx)
866 {
867 #ifdef CONFIG_HIGHMEM
868         return (idx == ZONE_HIGHMEM ||
869                 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
870 #else
871         return 0;
872 #endif
873 }
874 
875 /**
876  * is_highmem - helper function to quickly check if a struct zone is a 
877  *              highmem zone or not.  This is an attempt to keep references
878  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
879  * @zone - pointer to struct zone variable
880  */
881 static inline int is_highmem(struct zone *zone)
882 {
883 #ifdef CONFIG_HIGHMEM
884         int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
885         return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
886                (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
887                 zone_movable_is_highmem());
888 #else
889         return 0;
890 #endif
891 }
892 
893 /* These two functions are used to setup the per zone pages min values */
894 struct ctl_table;
895 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
896                                         void __user *, size_t *, loff_t *);
897 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
898 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
899                                         void __user *, size_t *, loff_t *);
900 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
901                                         void __user *, size_t *, loff_t *);
902 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
903                         void __user *, size_t *, loff_t *);
904 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
905                         void __user *, size_t *, loff_t *);
906 
907 extern int numa_zonelist_order_handler(struct ctl_table *, int,
908                         void __user *, size_t *, loff_t *);
909 extern char numa_zonelist_order[];
910 #define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
911 
912 #ifndef CONFIG_NEED_MULTIPLE_NODES
913 
914 extern struct pglist_data contig_page_data;
915 #define NODE_DATA(nid)          (&contig_page_data)
916 #define NODE_MEM_MAP(nid)       mem_map
917 
918 #else /* CONFIG_NEED_MULTIPLE_NODES */
919 
920 #include <asm/mmzone.h>
921 
922 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
923 
924 extern struct pglist_data *first_online_pgdat(void);
925 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
926 extern struct zone *next_zone(struct zone *zone);
927 
928 /**
929  * for_each_online_pgdat - helper macro to iterate over all online nodes
930  * @pgdat - pointer to a pg_data_t variable
931  */
932 #define for_each_online_pgdat(pgdat)                    \
933         for (pgdat = first_online_pgdat();              \
934              pgdat;                                     \
935              pgdat = next_online_pgdat(pgdat))
936 /**
937  * for_each_zone - helper macro to iterate over all memory zones
938  * @zone - pointer to struct zone variable
939  *
940  * The user only needs to declare the zone variable, for_each_zone
941  * fills it in.
942  */
943 #define for_each_zone(zone)                             \
944         for (zone = (first_online_pgdat())->node_zones; \
945              zone;                                      \
946              zone = next_zone(zone))
947 
948 #define for_each_populated_zone(zone)                   \
949         for (zone = (first_online_pgdat())->node_zones; \
950              zone;                                      \
951              zone = next_zone(zone))                    \
952                 if (!populated_zone(zone))              \
953                         ; /* do nothing */              \
954                 else
955 
956 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
957 {
958         return zoneref->zone;
959 }
960 
961 static inline int zonelist_zone_idx(struct zoneref *zoneref)
962 {
963         return zoneref->zone_idx;
964 }
965 
966 static inline int zonelist_node_idx(struct zoneref *zoneref)
967 {
968 #ifdef CONFIG_NUMA
969         /* zone_to_nid not available in this context */
970         return zoneref->zone->node;
971 #else
972         return 0;
973 #endif /* CONFIG_NUMA */
974 }
975 
976 /**
977  * 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
978  * @z - The cursor used as a starting point for the search
979  * @highest_zoneidx - The zone index of the highest zone to return
980  * @nodes - An optional nodemask to filter the zonelist with
981  * @zone - The first suitable zone found is returned via this parameter
982  *
983  * This function returns the next zone at or below a given zone index that is
984  * within the allowed nodemask using a cursor as the starting point for the
985  * search. The zoneref returned is a cursor that represents the current zone
986  * being examined. It should be advanced by one before calling
987  * next_zones_zonelist again.
988  */
989 struct zoneref *next_zones_zonelist(struct zoneref *z,
990                                         enum zone_type highest_zoneidx,
991                                         nodemask_t *nodes,
992                                         struct zone **zone);
993 
994 /**
995  * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
996  * @zonelist - The zonelist to search for a suitable zone
997  * @highest_zoneidx - The zone index of the highest zone to return
998  * @nodes - An optional nodemask to filter the zonelist with
999  * @zone - The first suitable zone found is returned via this parameter
1000  *
1001  * This function returns the first zone at or below a given zone index that is
1002  * within the allowed nodemask. The zoneref returned is a cursor that can be
1003  * used to iterate the zonelist with next_zones_zonelist by advancing it by
1004  * one before calling.
1005  */
1006 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
1007                                         enum zone_type highest_zoneidx,
1008                                         nodemask_t *nodes,
1009                                         struct zone **zone)
1010 {
1011         return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
1012                                                                 zone);
1013 }
1014 
1015 /**
1016  * 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
1017  * @zone - The current zone in the iterator
1018  * @z - The current pointer within zonelist->zones being iterated
1019  * @zlist - The zonelist being iterated
1020  * @highidx - The zone index of the highest zone to return
1021  * @nodemask - Nodemask allowed by the allocator
1022  *
1023  * This iterator iterates though all zones at or below a given zone index and
1024  * within a given nodemask
1025  */
1026 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1027         for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
1028                 zone;                                                   \
1029                 z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
1030 
1031 /**
1032  * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1033  * @zone - The current zone in the iterator
1034  * @z - The current pointer within zonelist->zones being iterated
1035  * @zlist - The zonelist being iterated
1036  * @highidx - The zone index of the highest zone to return
1037  *
1038  * This iterator iterates though all zones at or below a given zone index.
1039  */
1040 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1041         for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1042 
1043 #ifdef CONFIG_SPARSEMEM
1044 #include <asm/sparsemem.h>
1045 #endif
1046 
1047 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1048         !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1049 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1050 {
1051         return 0;
1052 }
1053 #endif
1054 
1055 #ifdef CONFIG_FLATMEM
1056 #define pfn_to_nid(pfn)         (0)
1057 #endif
1058 
1059 #ifdef CONFIG_SPARSEMEM
1060 
1061 /*
1062  * SECTION_SHIFT                #bits space required to store a section #
1063  *
1064  * PA_SECTION_SHIFT             physical address to/from section number
1065  * PFN_SECTION_SHIFT            pfn to/from section number
1066  */
1067 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1068 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1069 
1070 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1071 
1072 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1073 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1074 
1075 #define SECTION_BLOCKFLAGS_BITS \
1076         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1077 
1078 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1079 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1080 #endif
1081 
1082 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1083 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1084 
1085 #define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1086 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1087 
1088 struct page;
1089 struct page_cgroup;
1090 struct mem_section {
1091         /*
1092          * This is, logically, a pointer to an array of struct
1093          * pages.  However, it is stored with some other magic.
1094          * (see sparse.c::sparse_init_one_section())
1095          *
1096          * Additionally during early boot we encode node id of
1097          * the location of the section here to guide allocation.
1098          * (see sparse.c::memory_present())
1099          *
1100          * Making it a UL at least makes someone do a cast
1101          * before using it wrong.
1102          */
1103         unsigned long section_mem_map;
1104 
1105         /* See declaration of similar field in struct zone */
1106         unsigned long *pageblock_flags;
1107 #ifdef CONFIG_MEMCG
1108         /*
1109          * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1110          * section. (see memcontrol.h/page_cgroup.h about this.)
1111          */
1112         struct page_cgroup *page_cgroup;
1113         unsigned long pad;
1114 #endif
1115         /*
1116          * WARNING: mem_section must be a power-of-2 in size for the
1117          * calculation and use of SECTION_ROOT_MASK to make sense.
1118          */
1119 };
1120 
1121 #ifdef CONFIG_SPARSEMEM_EXTREME
1122 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1123 #else
1124 #define SECTIONS_PER_ROOT       1
1125 #endif
1126 
1127 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1128 #define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1129 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1130 
1131 #ifdef CONFIG_SPARSEMEM_EXTREME
1132 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1133 #else
1134 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1135 #endif
1136 
1137 static inline struct mem_section *__nr_to_section(unsigned long nr)
1138 {
1139         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1140                 return NULL;
1141         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1142 }
1143 extern int __section_nr(struct mem_section* ms);
1144 extern unsigned long usemap_size(void);
1145 
1146 /*
1147  * We use the lower bits of the mem_map pointer to store
1148  * a little bit of information.  There should be at least
1149  * 3 bits here due to 32-bit alignment.
1150  */
1151 #define SECTION_MARKED_PRESENT  (1UL<<0)
1152 #define SECTION_HAS_MEM_MAP     (1UL<<1)
1153 #define SECTION_MAP_LAST_BIT    (1UL<<2)
1154 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1155 #define SECTION_NID_SHIFT       2
1156 
1157 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1158 {
1159         unsigned long map = section->section_mem_map;
1160         map &= SECTION_MAP_MASK;
1161         return (struct page *)map;
1162 }
1163 
1164 static inline int present_section(struct mem_section *section)
1165 {
1166         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1167 }
1168 
1169 static inline int present_section_nr(unsigned long nr)
1170 {
1171         return present_section(__nr_to_section(nr));
1172 }
1173 
1174 static inline int valid_section(struct mem_section *section)
1175 {
1176         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1177 }
1178 
1179 static inline int valid_section_nr(unsigned long nr)
1180 {
1181         return valid_section(__nr_to_section(nr));
1182 }
1183 
1184 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1185 {
1186         return __nr_to_section(pfn_to_section_nr(pfn));
1187 }
1188 
1189 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1190 static inline int pfn_valid(unsigned long pfn)
1191 {
1192         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1193                 return 0;
1194         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1195 }
1196 #endif
1197 
1198 static inline int pfn_present(unsigned long pfn)
1199 {
1200         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1201                 return 0;
1202         return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1203 }
1204 
1205 /*
1206  * These are _only_ used during initialisation, therefore they
1207  * can use __initdata ...  They could have names to indicate
1208  * this restriction.
1209  */
1210 #ifdef CONFIG_NUMA
1211 #define pfn_to_nid(pfn)                                                 \
1212 ({                                                                      \
1213         unsigned long __pfn_to_nid_pfn = (pfn);                         \
1214         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1215 })
1216 #else
1217 #define pfn_to_nid(pfn)         (0)
1218 #endif
1219 
1220 #define early_pfn_valid(pfn)    pfn_valid(pfn)
1221 void sparse_init(void);
1222 #else
1223 #define sparse_init()   do {} while (0)
1224 #define sparse_index_init(_sec, _nid)  do {} while (0)
1225 #endif /* CONFIG_SPARSEMEM */
1226 
1227 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
1228 bool early_pfn_in_nid(unsigned long pfn, int nid);
1229 #else
1230 #define early_pfn_in_nid(pfn, nid)      (1)
1231 #endif
1232 
1233 #ifndef early_pfn_valid
1234 #define early_pfn_valid(pfn)    (1)
1235 #endif
1236 
1237 void memory_present(int nid, unsigned long start, unsigned long end);
1238 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1239 
1240 /*
1241  * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1242  * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1243  * pfn_valid_within() should be used in this case; we optimise this away
1244  * when we have no holes within a MAX_ORDER_NR_PAGES block.
1245  */
1246 #ifdef CONFIG_HOLES_IN_ZONE
1247 #define pfn_valid_within(pfn) pfn_valid(pfn)
1248 #else
1249 #define pfn_valid_within(pfn) (1)
1250 #endif
1251 
1252 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1253 /*
1254  * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1255  * associated with it or not. In FLATMEM, it is expected that holes always
1256  * have valid memmap as long as there is valid PFNs either side of the hole.
1257  * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1258  * entire section.
1259  *
1260  * However, an ARM, and maybe other embedded architectures in the future
1261  * free memmap backing holes to save memory on the assumption the memmap is
1262  * never used. The page_zone linkages are then broken even though pfn_valid()
1263  * returns true. A walker of the full memmap must then do this additional
1264  * check to ensure the memmap they are looking at is sane by making sure
1265  * the zone and PFN linkages are still valid. This is expensive, but walkers
1266  * of the full memmap are extremely rare.
1267  */
1268 int memmap_valid_within(unsigned long pfn,
1269                                         struct page *page, struct zone *zone);
1270 #else
1271 static inline int memmap_valid_within(unsigned long pfn,
1272                                         struct page *page, struct zone *zone)
1273 {
1274         return 1;
1275 }
1276 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1277 
1278 #endif /* !__GENERATING_BOUNDS.H */
1279 #endif /* !__ASSEMBLY__ */
1280 #endif /* _LINUX_MMZONE_H */
1281 

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