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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         NR_PAGES_SCANNED,       /* pages scanned since last reclaim */
147 #ifdef CONFIG_NUMA
148         NUMA_HIT,               /* allocated in intended node */
149         NUMA_MISS,              /* allocated in non intended node */
150         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
151         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
152         NUMA_LOCAL,             /* allocation from local node */
153         NUMA_OTHER,             /* allocation from other node */
154 #endif
155         WORKINGSET_REFAULT,
156         WORKINGSET_ACTIVATE,
157         WORKINGSET_NODERECLAIM,
158         NR_ANON_TRANSPARENT_HUGEPAGES,
159         NR_FREE_CMA_PAGES,
160         NR_VM_ZONE_STAT_ITEMS };
161 
162 /*
163  * We do arithmetic on the LRU lists in various places in the code,
164  * so it is important to keep the active lists LRU_ACTIVE higher in
165  * the array than the corresponding inactive lists, and to keep
166  * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
167  *
168  * This has to be kept in sync with the statistics in zone_stat_item
169  * above and the descriptions in vmstat_text in mm/vmstat.c
170  */
171 #define LRU_BASE 0
172 #define LRU_ACTIVE 1
173 #define LRU_FILE 2
174 
175 enum lru_list {
176         LRU_INACTIVE_ANON = LRU_BASE,
177         LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
178         LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
179         LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
180         LRU_UNEVICTABLE,
181         NR_LRU_LISTS
182 };
183 
184 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
185 
186 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
187 
188 static inline int is_file_lru(enum lru_list lru)
189 {
190         return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
191 }
192 
193 static inline int is_active_lru(enum lru_list lru)
194 {
195         return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
196 }
197 
198 static inline int is_unevictable_lru(enum lru_list lru)
199 {
200         return (lru == LRU_UNEVICTABLE);
201 }
202 
203 struct zone_reclaim_stat {
204         /*
205          * The pageout code in vmscan.c keeps track of how many of the
206          * mem/swap backed and file backed pages are referenced.
207          * The higher the rotated/scanned ratio, the more valuable
208          * that cache is.
209          *
210          * The anon LRU stats live in [0], file LRU stats in [1]
211          */
212         unsigned long           recent_rotated[2];
213         unsigned long           recent_scanned[2];
214 };
215 
216 struct lruvec {
217         struct list_head lists[NR_LRU_LISTS];
218         struct zone_reclaim_stat reclaim_stat;
219 #ifdef CONFIG_MEMCG
220         struct zone *zone;
221 #endif
222 };
223 
224 /* Mask used at gathering information at once (see memcontrol.c) */
225 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
226 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
227 #define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
228 
229 /* Isolate clean file */
230 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
231 /* Isolate unmapped file */
232 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
233 /* Isolate for asynchronous migration */
234 #define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
235 /* Isolate unevictable pages */
236 #define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
237 
238 /* LRU Isolation modes. */
239 typedef unsigned __bitwise__ isolate_mode_t;
240 
241 enum zone_watermarks {
242         WMARK_MIN,
243         WMARK_LOW,
244         WMARK_HIGH,
245         NR_WMARK
246 };
247 
248 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
249 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
250 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
251 
252 struct per_cpu_pages {
253         int count;              /* number of pages in the list */
254         int high;               /* high watermark, emptying needed */
255         int batch;              /* chunk size for buddy add/remove */
256 
257         /* Lists of pages, one per migrate type stored on the pcp-lists */
258         struct list_head lists[MIGRATE_PCPTYPES];
259 };
260 
261 struct per_cpu_pageset {
262         struct per_cpu_pages pcp;
263 #ifdef CONFIG_NUMA
264         s8 expire;
265 #endif
266 #ifdef CONFIG_SMP
267         s8 stat_threshold;
268         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
269 #endif
270 };
271 
272 #endif /* !__GENERATING_BOUNDS.H */
273 
274 enum zone_type {
275 #ifdef CONFIG_ZONE_DMA
276         /*
277          * ZONE_DMA is used when there are devices that are not able
278          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
279          * carve out the portion of memory that is needed for these devices.
280          * The range is arch specific.
281          *
282          * Some examples
283          *
284          * Architecture         Limit
285          * ---------------------------
286          * parisc, ia64, sparc  <4G
287          * s390                 <2G
288          * arm                  Various
289          * alpha                Unlimited or 0-16MB.
290          *
291          * i386, x86_64 and multiple other arches
292          *                      <16M.
293          */
294         ZONE_DMA,
295 #endif
296 #ifdef CONFIG_ZONE_DMA32
297         /*
298          * x86_64 needs two ZONE_DMAs because it supports devices that are
299          * only able to do DMA to the lower 16M but also 32 bit devices that
300          * can only do DMA areas below 4G.
301          */
302         ZONE_DMA32,
303 #endif
304         /*
305          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
306          * performed on pages in ZONE_NORMAL if the DMA devices support
307          * transfers to all addressable memory.
308          */
309         ZONE_NORMAL,
310 #ifdef CONFIG_HIGHMEM
311         /*
312          * A memory area that is only addressable by the kernel through
313          * mapping portions into its own address space. This is for example
314          * used by i386 to allow the kernel to address the memory beyond
315          * 900MB. The kernel will set up special mappings (page
316          * table entries on i386) for each page that the kernel needs to
317          * access.
318          */
319         ZONE_HIGHMEM,
320 #endif
321         ZONE_MOVABLE,
322         __MAX_NR_ZONES
323 };
324 
325 #ifndef __GENERATING_BOUNDS_H
326 
327 struct zone {
328         /* Read-mostly fields */
329 
330         /* zone watermarks, access with *_wmark_pages(zone) macros */
331         unsigned long watermark[NR_WMARK];
332 
333         /*
334          * We don't know if the memory that we're going to allocate will be freeable
335          * or/and it will be released eventually, so to avoid totally wasting several
336          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
337          * to run OOM on the lower zones despite there's tons of freeable ram
338          * on the higher zones). This array is recalculated at runtime if the
339          * sysctl_lowmem_reserve_ratio sysctl changes.
340          */
341         long lowmem_reserve[MAX_NR_ZONES];
342 
343 #ifdef CONFIG_NUMA
344         int node;
345 #endif
346 
347         /*
348          * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
349          * this zone's LRU.  Maintained by the pageout code.
350          */
351         unsigned int inactive_ratio;
352 
353         struct pglist_data      *zone_pgdat;
354         struct per_cpu_pageset __percpu *pageset;
355 
356         /*
357          * This is a per-zone reserve of pages that should not be
358          * considered dirtyable memory.
359          */
360         unsigned long           dirty_balance_reserve;
361 
362 #ifndef CONFIG_SPARSEMEM
363         /*
364          * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
365          * In SPARSEMEM, this map is stored in struct mem_section
366          */
367         unsigned long           *pageblock_flags;
368 #endif /* CONFIG_SPARSEMEM */
369 
370 #ifdef CONFIG_NUMA
371         /*
372          * zone reclaim becomes active if more unmapped pages exist.
373          */
374         unsigned long           min_unmapped_pages;
375         unsigned long           min_slab_pages;
376 #endif /* CONFIG_NUMA */
377 
378         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
379         unsigned long           zone_start_pfn;
380 
381         /*
382          * spanned_pages is the total pages spanned by the zone, including
383          * holes, which is calculated as:
384          *      spanned_pages = zone_end_pfn - zone_start_pfn;
385          *
386          * present_pages is physical pages existing within the zone, which
387          * is calculated as:
388          *      present_pages = spanned_pages - absent_pages(pages in holes);
389          *
390          * managed_pages is present pages managed by the buddy system, which
391          * is calculated as (reserved_pages includes pages allocated by the
392          * bootmem allocator):
393          *      managed_pages = present_pages - reserved_pages;
394          *
395          * So present_pages may be used by memory hotplug or memory power
396          * management logic to figure out unmanaged pages by checking
397          * (present_pages - managed_pages). And managed_pages should be used
398          * by page allocator and vm scanner to calculate all kinds of watermarks
399          * and thresholds.
400          *
401          * Locking rules:
402          *
403          * zone_start_pfn and spanned_pages are protected by span_seqlock.
404          * It is a seqlock because it has to be read outside of zone->lock,
405          * and it is done in the main allocator path.  But, it is written
406          * quite infrequently.
407          *
408          * The span_seq lock is declared along with zone->lock because it is
409          * frequently read in proximity to zone->lock.  It's good to
410          * give them a chance of being in the same cacheline.
411          *
412          * Write access to present_pages at runtime should be protected by
413          * mem_hotplug_begin/end(). Any reader who can't tolerant drift of
414          * present_pages should get_online_mems() to get a stable value.
415          *
416          * Read access to managed_pages should be safe because it's unsigned
417          * long. Write access to zone->managed_pages and totalram_pages are
418          * protected by managed_page_count_lock at runtime. Idealy only
419          * adjust_managed_page_count() should be used instead of directly
420          * touching zone->managed_pages and totalram_pages.
421          */
422         unsigned long           managed_pages;
423         unsigned long           spanned_pages;
424         unsigned long           present_pages;
425 
426         const char              *name;
427 
428         /*
429          * Number of MIGRATE_RESEVE page block. To maintain for just
430          * optimization. Protected by zone->lock.
431          */
432         int                     nr_migrate_reserve_block;
433 
434 #ifdef CONFIG_MEMORY_ISOLATION
435         /*
436          * Number of isolated pageblock. It is used to solve incorrect
437          * freepage counting problem due to racy retrieving migratetype
438          * of pageblock. Protected by zone->lock.
439          */
440         unsigned long           nr_isolate_pageblock;
441 #endif
442 
443 #ifdef CONFIG_MEMORY_HOTPLUG
444         /* see spanned/present_pages for more description */
445         seqlock_t               span_seqlock;
446 #endif
447 
448         /*
449          * wait_table           -- the array holding the hash table
450          * wait_table_hash_nr_entries   -- the size of the hash table array
451          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
452          *
453          * The purpose of all these is to keep track of the people
454          * waiting for a page to become available and make them
455          * runnable again when possible. The trouble is that this
456          * consumes a lot of space, especially when so few things
457          * wait on pages at a given time. So instead of using
458          * per-page waitqueues, we use a waitqueue hash table.
459          *
460          * The bucket discipline is to sleep on the same queue when
461          * colliding and wake all in that wait queue when removing.
462          * When something wakes, it must check to be sure its page is
463          * truly available, a la thundering herd. The cost of a
464          * collision is great, but given the expected load of the
465          * table, they should be so rare as to be outweighed by the
466          * benefits from the saved space.
467          *
468          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
469          * primary users of these fields, and in mm/page_alloc.c
470          * free_area_init_core() performs the initialization of them.
471          */
472         wait_queue_head_t       *wait_table;
473         unsigned long           wait_table_hash_nr_entries;
474         unsigned long           wait_table_bits;
475 
476         ZONE_PADDING(_pad1_)
477 
478         /* Write-intensive fields used from the page allocator */
479         spinlock_t              lock;
480 
481         /* free areas of different sizes */
482         struct free_area        free_area[MAX_ORDER];
483 
484         /* zone flags, see below */
485         unsigned long           flags;
486 
487         ZONE_PADDING(_pad2_)
488 
489         /* Write-intensive fields used by page reclaim */
490 
491         /* Fields commonly accessed by the page reclaim scanner */
492         spinlock_t              lru_lock;
493         struct lruvec           lruvec;
494 
495         /* Evictions & activations on the inactive file list */
496         atomic_long_t           inactive_age;
497 
498         /*
499          * When free pages are below this point, additional steps are taken
500          * when reading the number of free pages to avoid per-cpu counter
501          * drift allowing watermarks to be breached
502          */
503         unsigned long percpu_drift_mark;
504 
505 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
506         /* pfn where compaction free scanner should start */
507         unsigned long           compact_cached_free_pfn;
508         /* pfn where async and sync compaction migration scanner should start */
509         unsigned long           compact_cached_migrate_pfn[2];
510 #endif
511 
512 #ifdef CONFIG_COMPACTION
513         /*
514          * On compaction failure, 1<<compact_defer_shift compactions
515          * are skipped before trying again. The number attempted since
516          * last failure is tracked with compact_considered.
517          */
518         unsigned int            compact_considered;
519         unsigned int            compact_defer_shift;
520         int                     compact_order_failed;
521 #endif
522 
523 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
524         /* Set to true when the PG_migrate_skip bits should be cleared */
525         bool                    compact_blockskip_flush;
526 #endif
527 
528         ZONE_PADDING(_pad3_)
529         /* Zone statistics */
530         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
531 } ____cacheline_internodealigned_in_smp;
532 
533 enum zone_flags {
534         ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
535         ZONE_OOM_LOCKED,                /* zone is in OOM killer zonelist */
536         ZONE_CONGESTED,                 /* zone has many dirty pages backed by
537                                          * a congested BDI
538                                          */
539         ZONE_DIRTY,                     /* reclaim scanning has recently found
540                                          * many dirty file pages at the tail
541                                          * of the LRU.
542                                          */
543         ZONE_WRITEBACK,                 /* reclaim scanning has recently found
544                                          * many pages under writeback
545                                          */
546         ZONE_FAIR_DEPLETED,             /* fair zone policy batch depleted */
547 };
548 
549 static inline unsigned long zone_end_pfn(const struct zone *zone)
550 {
551         return zone->zone_start_pfn + zone->spanned_pages;
552 }
553 
554 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
555 {
556         return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
557 }
558 
559 static inline bool zone_is_initialized(struct zone *zone)
560 {
561         return !!zone->wait_table;
562 }
563 
564 static inline bool zone_is_empty(struct zone *zone)
565 {
566         return zone->spanned_pages == 0;
567 }
568 
569 /*
570  * The "priority" of VM scanning is how much of the queues we will scan in one
571  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
572  * queues ("queue_length >> 12") during an aging round.
573  */
574 #define DEF_PRIORITY 12
575 
576 /* Maximum number of zones on a zonelist */
577 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
578 
579 #ifdef CONFIG_NUMA
580 
581 /*
582  * The NUMA zonelists are doubled because we need zonelists that restrict the
583  * allocations to a single node for __GFP_THISNODE.
584  *
585  * [0]  : Zonelist with fallback
586  * [1]  : No fallback (__GFP_THISNODE)
587  */
588 #define MAX_ZONELISTS 2
589 
590 
591 /*
592  * We cache key information from each zonelist for smaller cache
593  * footprint when scanning for free pages in get_page_from_freelist().
594  *
595  * 1) The BITMAP fullzones tracks which zones in a zonelist have come
596  *    up short of free memory since the last time (last_fullzone_zap)
597  *    we zero'd fullzones.
598  * 2) The array z_to_n[] maps each zone in the zonelist to its node
599  *    id, so that we can efficiently evaluate whether that node is
600  *    set in the current tasks mems_allowed.
601  *
602  * Both fullzones and z_to_n[] are one-to-one with the zonelist,
603  * indexed by a zones offset in the zonelist zones[] array.
604  *
605  * The get_page_from_freelist() routine does two scans.  During the
606  * first scan, we skip zones whose corresponding bit in 'fullzones'
607  * is set or whose corresponding node in current->mems_allowed (which
608  * comes from cpusets) is not set.  During the second scan, we bypass
609  * this zonelist_cache, to ensure we look methodically at each zone.
610  *
611  * Once per second, we zero out (zap) fullzones, forcing us to
612  * reconsider nodes that might have regained more free memory.
613  * The field last_full_zap is the time we last zapped fullzones.
614  *
615  * This mechanism reduces the amount of time we waste repeatedly
616  * reexaming zones for free memory when they just came up low on
617  * memory momentarilly ago.
618  *
619  * The zonelist_cache struct members logically belong in struct
620  * zonelist.  However, the mempolicy zonelists constructed for
621  * MPOL_BIND are intentionally variable length (and usually much
622  * shorter).  A general purpose mechanism for handling structs with
623  * multiple variable length members is more mechanism than we want
624  * here.  We resort to some special case hackery instead.
625  *
626  * The MPOL_BIND zonelists don't need this zonelist_cache (in good
627  * part because they are shorter), so we put the fixed length stuff
628  * at the front of the zonelist struct, ending in a variable length
629  * zones[], as is needed by MPOL_BIND.
630  *
631  * Then we put the optional zonelist cache on the end of the zonelist
632  * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
633  * the fixed length portion at the front of the struct.  This pointer
634  * both enables us to find the zonelist cache, and in the case of
635  * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
636  * to know that the zonelist cache is not there.
637  *
638  * The end result is that struct zonelists come in two flavors:
639  *  1) The full, fixed length version, shown below, and
640  *  2) The custom zonelists for MPOL_BIND.
641  * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
642  *
643  * Even though there may be multiple CPU cores on a node modifying
644  * fullzones or last_full_zap in the same zonelist_cache at the same
645  * time, we don't lock it.  This is just hint data - if it is wrong now
646  * and then, the allocator will still function, perhaps a bit slower.
647  */
648 
649 
650 struct zonelist_cache {
651         unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];          /* zone->nid */
652         DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);      /* zone full? */
653         unsigned long last_full_zap;            /* when last zap'd (jiffies) */
654 };
655 #else
656 #define MAX_ZONELISTS 1
657 struct zonelist_cache;
658 #endif
659 
660 /*
661  * This struct contains information about a zone in a zonelist. It is stored
662  * here to avoid dereferences into large structures and lookups of tables
663  */
664 struct zoneref {
665         struct zone *zone;      /* Pointer to actual zone */
666         int zone_idx;           /* zone_idx(zoneref->zone) */
667 };
668 
669 /*
670  * One allocation request operates on a zonelist. A zonelist
671  * is a list of zones, the first one is the 'goal' of the
672  * allocation, the other zones are fallback zones, in decreasing
673  * priority.
674  *
675  * If zlcache_ptr is not NULL, then it is just the address of zlcache,
676  * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
677  * *
678  * To speed the reading of the zonelist, the zonerefs contain the zone index
679  * of the entry being read. Helper functions to access information given
680  * a struct zoneref are
681  *
682  * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
683  * zonelist_zone_idx()  - Return the index of the zone for an entry
684  * zonelist_node_idx()  - Return the index of the node for an entry
685  */
686 struct zonelist {
687         struct zonelist_cache *zlcache_ptr;                  // NULL or &zlcache
688         struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
689 #ifdef CONFIG_NUMA
690         struct zonelist_cache zlcache;                       // optional ...
691 #endif
692 };
693 
694 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
695 struct node_active_region {
696         unsigned long start_pfn;
697         unsigned long end_pfn;
698         int nid;
699 };
700 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
701 
702 #ifndef CONFIG_DISCONTIGMEM
703 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
704 extern struct page *mem_map;
705 #endif
706 
707 /*
708  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
709  * (mostly NUMA machines?) to denote a higher-level memory zone than the
710  * zone denotes.
711  *
712  * On NUMA machines, each NUMA node would have a pg_data_t to describe
713  * it's memory layout.
714  *
715  * Memory statistics and page replacement data structures are maintained on a
716  * per-zone basis.
717  */
718 struct bootmem_data;
719 typedef struct pglist_data {
720         struct zone node_zones[MAX_NR_ZONES];
721         struct zonelist node_zonelists[MAX_ZONELISTS];
722         int nr_zones;
723 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
724         struct page *node_mem_map;
725 #ifdef CONFIG_MEMCG
726         struct page_cgroup *node_page_cgroup;
727 #endif
728 #endif
729 #ifndef CONFIG_NO_BOOTMEM
730         struct bootmem_data *bdata;
731 #endif
732 #ifdef CONFIG_MEMORY_HOTPLUG
733         /*
734          * Must be held any time you expect node_start_pfn, node_present_pages
735          * or node_spanned_pages stay constant.  Holding this will also
736          * guarantee that any pfn_valid() stays that way.
737          *
738          * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
739          * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG.
740          *
741          * Nests above zone->lock and zone->span_seqlock
742          */
743         spinlock_t node_size_lock;
744 #endif
745         unsigned long node_start_pfn;
746         unsigned long node_present_pages; /* total number of physical pages */
747         unsigned long node_spanned_pages; /* total size of physical page
748                                              range, including holes */
749         int node_id;
750         wait_queue_head_t kswapd_wait;
751         wait_queue_head_t pfmemalloc_wait;
752         struct task_struct *kswapd;     /* Protected by
753                                            mem_hotplug_begin/end() */
754         int kswapd_max_order;
755         enum zone_type classzone_idx;
756 #ifdef CONFIG_NUMA_BALANCING
757         /* Lock serializing the migrate rate limiting window */
758         spinlock_t numabalancing_migrate_lock;
759 
760         /* Rate limiting time interval */
761         unsigned long numabalancing_migrate_next_window;
762 
763         /* Number of pages migrated during the rate limiting time interval */
764         unsigned long numabalancing_migrate_nr_pages;
765 #endif
766 } pg_data_t;
767 
768 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
769 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
770 #ifdef CONFIG_FLAT_NODE_MEM_MAP
771 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
772 #else
773 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
774 #endif
775 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
776 
777 #define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
778 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
779 
780 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
781 {
782         return pgdat->node_start_pfn + pgdat->node_spanned_pages;
783 }
784 
785 static inline bool pgdat_is_empty(pg_data_t *pgdat)
786 {
787         return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
788 }
789 
790 #include <linux/memory_hotplug.h>
791 
792 extern struct mutex zonelists_mutex;
793 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
794 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
795 bool zone_watermark_ok(struct zone *z, unsigned int order,
796                 unsigned long mark, int classzone_idx, int alloc_flags);
797 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
798                 unsigned long mark, int classzone_idx, int alloc_flags);
799 enum memmap_context {
800         MEMMAP_EARLY,
801         MEMMAP_HOTPLUG,
802 };
803 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
804                                      unsigned long size,
805                                      enum memmap_context context);
806 
807 extern void lruvec_init(struct lruvec *lruvec);
808 
809 static inline struct zone *lruvec_zone(struct lruvec *lruvec)
810 {
811 #ifdef CONFIG_MEMCG
812         return lruvec->zone;
813 #else
814         return container_of(lruvec, struct zone, lruvec);
815 #endif
816 }
817 
818 #ifdef CONFIG_HAVE_MEMORY_PRESENT
819 void memory_present(int nid, unsigned long start, unsigned long end);
820 #else
821 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
822 #endif
823 
824 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
825 int local_memory_node(int node_id);
826 #else
827 static inline int local_memory_node(int node_id) { return node_id; };
828 #endif
829 
830 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
831 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
832 #endif
833 
834 /*
835  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
836  */
837 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
838 
839 static inline int populated_zone(struct zone *zone)
840 {
841         return (!!zone->present_pages);
842 }
843 
844 extern int movable_zone;
845 
846 static inline int zone_movable_is_highmem(void)
847 {
848 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
849         return movable_zone == ZONE_HIGHMEM;
850 #elif defined(CONFIG_HIGHMEM)
851         return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM;
852 #else
853         return 0;
854 #endif
855 }
856 
857 static inline int is_highmem_idx(enum zone_type idx)
858 {
859 #ifdef CONFIG_HIGHMEM
860         return (idx == ZONE_HIGHMEM ||
861                 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
862 #else
863         return 0;
864 #endif
865 }
866 
867 /**
868  * is_highmem - helper function to quickly check if a struct zone is a 
869  *              highmem zone or not.  This is an attempt to keep references
870  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
871  * @zone - pointer to struct zone variable
872  */
873 static inline int is_highmem(struct zone *zone)
874 {
875 #ifdef CONFIG_HIGHMEM
876         int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
877         return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
878                (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
879                 zone_movable_is_highmem());
880 #else
881         return 0;
882 #endif
883 }
884 
885 /* These two functions are used to setup the per zone pages min values */
886 struct ctl_table;
887 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
888                                         void __user *, size_t *, loff_t *);
889 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
890 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
891                                         void __user *, size_t *, loff_t *);
892 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
893                                         void __user *, size_t *, loff_t *);
894 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
895                         void __user *, size_t *, loff_t *);
896 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
897                         void __user *, size_t *, loff_t *);
898 
899 extern int numa_zonelist_order_handler(struct ctl_table *, int,
900                         void __user *, size_t *, loff_t *);
901 extern char numa_zonelist_order[];
902 #define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
903 
904 #ifndef CONFIG_NEED_MULTIPLE_NODES
905 
906 extern struct pglist_data contig_page_data;
907 #define NODE_DATA(nid)          (&contig_page_data)
908 #define NODE_MEM_MAP(nid)       mem_map
909 
910 #else /* CONFIG_NEED_MULTIPLE_NODES */
911 
912 #include <asm/mmzone.h>
913 
914 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
915 
916 extern struct pglist_data *first_online_pgdat(void);
917 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
918 extern struct zone *next_zone(struct zone *zone);
919 
920 /**
921  * for_each_online_pgdat - helper macro to iterate over all online nodes
922  * @pgdat - pointer to a pg_data_t variable
923  */
924 #define for_each_online_pgdat(pgdat)                    \
925         for (pgdat = first_online_pgdat();              \
926              pgdat;                                     \
927              pgdat = next_online_pgdat(pgdat))
928 /**
929  * for_each_zone - helper macro to iterate over all memory zones
930  * @zone - pointer to struct zone variable
931  *
932  * The user only needs to declare the zone variable, for_each_zone
933  * fills it in.
934  */
935 #define for_each_zone(zone)                             \
936         for (zone = (first_online_pgdat())->node_zones; \
937              zone;                                      \
938              zone = next_zone(zone))
939 
940 #define for_each_populated_zone(zone)                   \
941         for (zone = (first_online_pgdat())->node_zones; \
942              zone;                                      \
943              zone = next_zone(zone))                    \
944                 if (!populated_zone(zone))              \
945                         ; /* do nothing */              \
946                 else
947 
948 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
949 {
950         return zoneref->zone;
951 }
952 
953 static inline int zonelist_zone_idx(struct zoneref *zoneref)
954 {
955         return zoneref->zone_idx;
956 }
957 
958 static inline int zonelist_node_idx(struct zoneref *zoneref)
959 {
960 #ifdef CONFIG_NUMA
961         /* zone_to_nid not available in this context */
962         return zoneref->zone->node;
963 #else
964         return 0;
965 #endif /* CONFIG_NUMA */
966 }
967 
968 /**
969  * 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
970  * @z - The cursor used as a starting point for the search
971  * @highest_zoneidx - The zone index of the highest zone to return
972  * @nodes - An optional nodemask to filter the zonelist with
973  * @zone - The first suitable zone found is returned via this parameter
974  *
975  * This function returns the next zone at or below a given zone index that is
976  * within the allowed nodemask using a cursor as the starting point for the
977  * search. The zoneref returned is a cursor that represents the current zone
978  * being examined. It should be advanced by one before calling
979  * next_zones_zonelist again.
980  */
981 struct zoneref *next_zones_zonelist(struct zoneref *z,
982                                         enum zone_type highest_zoneidx,
983                                         nodemask_t *nodes,
984                                         struct zone **zone);
985 
986 /**
987  * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
988  * @zonelist - The zonelist to search for a suitable zone
989  * @highest_zoneidx - The zone index of the highest zone to return
990  * @nodes - An optional nodemask to filter the zonelist with
991  * @zone - The first suitable zone found is returned via this parameter
992  *
993  * This function returns the first zone at or below a given zone index that is
994  * within the allowed nodemask. The zoneref returned is a cursor that can be
995  * used to iterate the zonelist with next_zones_zonelist by advancing it by
996  * one before calling.
997  */
998 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
999                                         enum zone_type highest_zoneidx,
1000                                         nodemask_t *nodes,
1001                                         struct zone **zone)
1002 {
1003         return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
1004                                                                 zone);
1005 }
1006 
1007 /**
1008  * 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
1009  * @zone - The current zone in the iterator
1010  * @z - The current pointer within zonelist->zones being iterated
1011  * @zlist - The zonelist being iterated
1012  * @highidx - The zone index of the highest zone to return
1013  * @nodemask - Nodemask allowed by the allocator
1014  *
1015  * This iterator iterates though all zones at or below a given zone index and
1016  * within a given nodemask
1017  */
1018 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1019         for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
1020                 zone;                                                   \
1021                 z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
1022 
1023 /**
1024  * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1025  * @zone - The current zone in the iterator
1026  * @z - The current pointer within zonelist->zones being iterated
1027  * @zlist - The zonelist being iterated
1028  * @highidx - The zone index of the highest zone to return
1029  *
1030  * This iterator iterates though all zones at or below a given zone index.
1031  */
1032 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1033         for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1034 
1035 #ifdef CONFIG_SPARSEMEM
1036 #include <asm/sparsemem.h>
1037 #endif
1038 
1039 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1040         !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1041 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1042 {
1043         return 0;
1044 }
1045 #endif
1046 
1047 #ifdef CONFIG_FLATMEM
1048 #define pfn_to_nid(pfn)         (0)
1049 #endif
1050 
1051 #ifdef CONFIG_SPARSEMEM
1052 
1053 /*
1054  * SECTION_SHIFT                #bits space required to store a section #
1055  *
1056  * PA_SECTION_SHIFT             physical address to/from section number
1057  * PFN_SECTION_SHIFT            pfn to/from section number
1058  */
1059 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1060 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1061 
1062 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1063 
1064 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1065 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1066 
1067 #define SECTION_BLOCKFLAGS_BITS \
1068         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1069 
1070 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1071 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1072 #endif
1073 
1074 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1075 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1076 
1077 #define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1078 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1079 
1080 struct page;
1081 struct page_cgroup;
1082 struct mem_section {
1083         /*
1084          * This is, logically, a pointer to an array of struct
1085          * pages.  However, it is stored with some other magic.
1086          * (see sparse.c::sparse_init_one_section())
1087          *
1088          * Additionally during early boot we encode node id of
1089          * the location of the section here to guide allocation.
1090          * (see sparse.c::memory_present())
1091          *
1092          * Making it a UL at least makes someone do a cast
1093          * before using it wrong.
1094          */
1095         unsigned long section_mem_map;
1096 
1097         /* See declaration of similar field in struct zone */
1098         unsigned long *pageblock_flags;
1099 #ifdef CONFIG_MEMCG
1100         /*
1101          * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1102          * section. (see memcontrol.h/page_cgroup.h about this.)
1103          */
1104         struct page_cgroup *page_cgroup;
1105         unsigned long pad;
1106 #endif
1107         /*
1108          * WARNING: mem_section must be a power-of-2 in size for the
1109          * calculation and use of SECTION_ROOT_MASK to make sense.
1110          */
1111 };
1112 
1113 #ifdef CONFIG_SPARSEMEM_EXTREME
1114 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1115 #else
1116 #define SECTIONS_PER_ROOT       1
1117 #endif
1118 
1119 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1120 #define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1121 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1122 
1123 #ifdef CONFIG_SPARSEMEM_EXTREME
1124 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1125 #else
1126 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1127 #endif
1128 
1129 static inline struct mem_section *__nr_to_section(unsigned long nr)
1130 {
1131         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1132                 return NULL;
1133         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1134 }
1135 extern int __section_nr(struct mem_section* ms);
1136 extern unsigned long usemap_size(void);
1137 
1138 /*
1139  * We use the lower bits of the mem_map pointer to store
1140  * a little bit of information.  There should be at least
1141  * 3 bits here due to 32-bit alignment.
1142  */
1143 #define SECTION_MARKED_PRESENT  (1UL<<0)
1144 #define SECTION_HAS_MEM_MAP     (1UL<<1)
1145 #define SECTION_MAP_LAST_BIT    (1UL<<2)
1146 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1147 #define SECTION_NID_SHIFT       2
1148 
1149 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1150 {
1151         unsigned long map = section->section_mem_map;
1152         map &= SECTION_MAP_MASK;
1153         return (struct page *)map;
1154 }
1155 
1156 static inline int present_section(struct mem_section *section)
1157 {
1158         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1159 }
1160 
1161 static inline int present_section_nr(unsigned long nr)
1162 {
1163         return present_section(__nr_to_section(nr));
1164 }
1165 
1166 static inline int valid_section(struct mem_section *section)
1167 {
1168         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1169 }
1170 
1171 static inline int valid_section_nr(unsigned long nr)
1172 {
1173         return valid_section(__nr_to_section(nr));
1174 }
1175 
1176 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1177 {
1178         return __nr_to_section(pfn_to_section_nr(pfn));
1179 }
1180 
1181 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1182 static inline int pfn_valid(unsigned long pfn)
1183 {
1184         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1185                 return 0;
1186         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1187 }
1188 #endif
1189 
1190 static inline int pfn_present(unsigned long pfn)
1191 {
1192         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1193                 return 0;
1194         return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1195 }
1196 
1197 /*
1198  * These are _only_ used during initialisation, therefore they
1199  * can use __initdata ...  They could have names to indicate
1200  * this restriction.
1201  */
1202 #ifdef CONFIG_NUMA
1203 #define pfn_to_nid(pfn)                                                 \
1204 ({                                                                      \
1205         unsigned long __pfn_to_nid_pfn = (pfn);                         \
1206         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1207 })
1208 #else
1209 #define pfn_to_nid(pfn)         (0)
1210 #endif
1211 
1212 #define early_pfn_valid(pfn)    pfn_valid(pfn)
1213 void sparse_init(void);
1214 #else
1215 #define sparse_init()   do {} while (0)
1216 #define sparse_index_init(_sec, _nid)  do {} while (0)
1217 #endif /* CONFIG_SPARSEMEM */
1218 
1219 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
1220 bool early_pfn_in_nid(unsigned long pfn, int nid);
1221 #else
1222 #define early_pfn_in_nid(pfn, nid)      (1)
1223 #endif
1224 
1225 #ifndef early_pfn_valid
1226 #define early_pfn_valid(pfn)    (1)
1227 #endif
1228 
1229 void memory_present(int nid, unsigned long start, unsigned long end);
1230 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1231 
1232 /*
1233  * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1234  * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1235  * pfn_valid_within() should be used in this case; we optimise this away
1236  * when we have no holes within a MAX_ORDER_NR_PAGES block.
1237  */
1238 #ifdef CONFIG_HOLES_IN_ZONE
1239 #define pfn_valid_within(pfn) pfn_valid(pfn)
1240 #else
1241 #define pfn_valid_within(pfn) (1)
1242 #endif
1243 
1244 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1245 /*
1246  * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1247  * associated with it or not. In FLATMEM, it is expected that holes always
1248  * have valid memmap as long as there is valid PFNs either side of the hole.
1249  * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1250  * entire section.
1251  *
1252  * However, an ARM, and maybe other embedded architectures in the future
1253  * free memmap backing holes to save memory on the assumption the memmap is
1254  * never used. The page_zone linkages are then broken even though pfn_valid()
1255  * returns true. A walker of the full memmap must then do this additional
1256  * check to ensure the memmap they are looking at is sane by making sure
1257  * the zone and PFN linkages are still valid. This is expensive, but walkers
1258  * of the full memmap are extremely rare.
1259  */
1260 int memmap_valid_within(unsigned long pfn,
1261                                         struct page *page, struct zone *zone);
1262 #else
1263 static inline int memmap_valid_within(unsigned long pfn,
1264                                         struct page *page, struct zone *zone)
1265 {
1266         return 1;
1267 }
1268 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1269 
1270 #endif /* !__GENERATING_BOUNDS.H */
1271 #endif /* !__ASSEMBLY__ */
1272 #endif /* _LINUX_MMZONE_H */
1273 

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