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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_MOVABLE,
 41         MIGRATE_RECLAIMABLE,
 42         MIGRATE_PCPTYPES,       /* the number of types on the pcp lists */
 43         MIGRATE_HIGHATOMIC = 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 /* In mm/page_alloc.c; keep in sync also with show_migration_types() there */
 67 extern char * const migratetype_names[MIGRATE_TYPES];
 68 
 69 #ifdef CONFIG_CMA
 70 #  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
 71 #  define is_migrate_cma_page(_page) (get_pageblock_migratetype(_page) == MIGRATE_CMA)
 72 #else
 73 #  define is_migrate_cma(migratetype) false
 74 #  define is_migrate_cma_page(_page) false
 75 #endif
 76 
 77 #define for_each_migratetype_order(order, type) \
 78         for (order = 0; order < MAX_ORDER; order++) \
 79                 for (type = 0; type < MIGRATE_TYPES; type++)
 80 
 81 extern int page_group_by_mobility_disabled;
 82 
 83 #define NR_MIGRATETYPE_BITS (PB_migrate_end - PB_migrate + 1)
 84 #define MIGRATETYPE_MASK ((1UL << NR_MIGRATETYPE_BITS) - 1)
 85 
 86 #define get_pageblock_migratetype(page)                                 \
 87         get_pfnblock_flags_mask(page, page_to_pfn(page),                \
 88                         PB_migrate_end, MIGRATETYPE_MASK)
 89 
 90 struct free_area {
 91         struct list_head        free_list[MIGRATE_TYPES];
 92         unsigned long           nr_free;
 93 };
 94 
 95 struct pglist_data;
 96 
 97 /*
 98  * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
 99  * So add a wild amount of padding here to ensure that they fall into separate
100  * cachelines.  There are very few zone structures in the machine, so space
101  * consumption is not a concern here.
102  */
103 #if defined(CONFIG_SMP)
104 struct zone_padding {
105         char x[0];
106 } ____cacheline_internodealigned_in_smp;
107 #define ZONE_PADDING(name)      struct zone_padding name;
108 #else
109 #define ZONE_PADDING(name)
110 #endif
111 
112 enum zone_stat_item {
113         /* First 128 byte cacheline (assuming 64 bit words) */
114         NR_FREE_PAGES,
115         NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
116         NR_ZONE_INACTIVE_ANON = NR_ZONE_LRU_BASE,
117         NR_ZONE_ACTIVE_ANON,
118         NR_ZONE_INACTIVE_FILE,
119         NR_ZONE_ACTIVE_FILE,
120         NR_ZONE_UNEVICTABLE,
121         NR_ZONE_WRITE_PENDING,  /* Count of dirty, writeback and unstable pages */
122         NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
123         NR_SLAB_RECLAIMABLE,
124         NR_SLAB_UNRECLAIMABLE,
125         NR_PAGETABLE,           /* used for pagetables */
126         NR_KERNEL_STACK_KB,     /* measured in KiB */
127         /* Second 128 byte cacheline */
128         NR_BOUNCE,
129 #if IS_ENABLED(CONFIG_ZSMALLOC)
130         NR_ZSPAGES,             /* allocated in zsmalloc */
131 #endif
132 #ifdef CONFIG_NUMA
133         NUMA_HIT,               /* allocated in intended node */
134         NUMA_MISS,              /* allocated in non intended node */
135         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
136         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
137         NUMA_LOCAL,             /* allocation from local node */
138         NUMA_OTHER,             /* allocation from other node */
139 #endif
140         NR_FREE_CMA_PAGES,
141         NR_VM_ZONE_STAT_ITEMS };
142 
143 enum node_stat_item {
144         NR_LRU_BASE,
145         NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
146         NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
147         NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
148         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
149         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
150         NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
151         NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
152         NR_PAGES_SCANNED,       /* pages scanned since last reclaim */
153         WORKINGSET_REFAULT,
154         WORKINGSET_ACTIVATE,
155         WORKINGSET_NODERECLAIM,
156         NR_ANON_MAPPED, /* Mapped anonymous pages */
157         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
158                            only modified from process context */
159         NR_FILE_PAGES,
160         NR_FILE_DIRTY,
161         NR_WRITEBACK,
162         NR_WRITEBACK_TEMP,      /* Writeback using temporary buffers */
163         NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
164         NR_SHMEM_THPS,
165         NR_SHMEM_PMDMAPPED,
166         NR_ANON_THPS,
167         NR_UNSTABLE_NFS,        /* NFS unstable pages */
168         NR_VMSCAN_WRITE,
169         NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
170         NR_DIRTIED,             /* page dirtyings since bootup */
171         NR_WRITTEN,             /* page writings since bootup */
172         NR_VM_NODE_STAT_ITEMS
173 };
174 
175 /*
176  * We do arithmetic on the LRU lists in various places in the code,
177  * so it is important to keep the active lists LRU_ACTIVE higher in
178  * the array than the corresponding inactive lists, and to keep
179  * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
180  *
181  * This has to be kept in sync with the statistics in zone_stat_item
182  * above and the descriptions in vmstat_text in mm/vmstat.c
183  */
184 #define LRU_BASE 0
185 #define LRU_ACTIVE 1
186 #define LRU_FILE 2
187 
188 enum lru_list {
189         LRU_INACTIVE_ANON = LRU_BASE,
190         LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
191         LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
192         LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
193         LRU_UNEVICTABLE,
194         NR_LRU_LISTS
195 };
196 
197 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
198 
199 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
200 
201 static inline int is_file_lru(enum lru_list lru)
202 {
203         return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
204 }
205 
206 static inline int is_active_lru(enum lru_list lru)
207 {
208         return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
209 }
210 
211 struct zone_reclaim_stat {
212         /*
213          * The pageout code in vmscan.c keeps track of how many of the
214          * mem/swap backed and file backed pages are referenced.
215          * The higher the rotated/scanned ratio, the more valuable
216          * that cache is.
217          *
218          * The anon LRU stats live in [0], file LRU stats in [1]
219          */
220         unsigned long           recent_rotated[2];
221         unsigned long           recent_scanned[2];
222 };
223 
224 struct lruvec {
225         struct list_head                lists[NR_LRU_LISTS];
226         struct zone_reclaim_stat        reclaim_stat;
227         /* Evictions & activations on the inactive file list */
228         atomic_long_t                   inactive_age;
229 #ifdef CONFIG_MEMCG
230         struct pglist_data *pgdat;
231 #endif
232 };
233 
234 /* Mask used at gathering information at once (see memcontrol.c) */
235 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
236 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
237 #define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
238 
239 /* Isolate clean file */
240 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
241 /* Isolate unmapped file */
242 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
243 /* Isolate for asynchronous migration */
244 #define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
245 /* Isolate unevictable pages */
246 #define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
247 
248 /* LRU Isolation modes. */
249 typedef unsigned __bitwise__ isolate_mode_t;
250 
251 enum zone_watermarks {
252         WMARK_MIN,
253         WMARK_LOW,
254         WMARK_HIGH,
255         NR_WMARK
256 };
257 
258 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
259 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
260 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
261 
262 struct per_cpu_pages {
263         int count;              /* number of pages in the list */
264         int high;               /* high watermark, emptying needed */
265         int batch;              /* chunk size for buddy add/remove */
266 
267         /* Lists of pages, one per migrate type stored on the pcp-lists */
268         struct list_head lists[MIGRATE_PCPTYPES];
269 };
270 
271 struct per_cpu_pageset {
272         struct per_cpu_pages pcp;
273 #ifdef CONFIG_NUMA
274         s8 expire;
275 #endif
276 #ifdef CONFIG_SMP
277         s8 stat_threshold;
278         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
279 #endif
280 };
281 
282 struct per_cpu_nodestat {
283         s8 stat_threshold;
284         s8 vm_node_stat_diff[NR_VM_NODE_STAT_ITEMS];
285 };
286 
287 #endif /* !__GENERATING_BOUNDS.H */
288 
289 enum zone_type {
290 #ifdef CONFIG_ZONE_DMA
291         /*
292          * ZONE_DMA is used when there are devices that are not able
293          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
294          * carve out the portion of memory that is needed for these devices.
295          * The range is arch specific.
296          *
297          * Some examples
298          *
299          * Architecture         Limit
300          * ---------------------------
301          * parisc, ia64, sparc  <4G
302          * s390                 <2G
303          * arm                  Various
304          * alpha                Unlimited or 0-16MB.
305          *
306          * i386, x86_64 and multiple other arches
307          *                      <16M.
308          */
309         ZONE_DMA,
310 #endif
311 #ifdef CONFIG_ZONE_DMA32
312         /*
313          * x86_64 needs two ZONE_DMAs because it supports devices that are
314          * only able to do DMA to the lower 16M but also 32 bit devices that
315          * can only do DMA areas below 4G.
316          */
317         ZONE_DMA32,
318 #endif
319         /*
320          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
321          * performed on pages in ZONE_NORMAL if the DMA devices support
322          * transfers to all addressable memory.
323          */
324         ZONE_NORMAL,
325 #ifdef CONFIG_HIGHMEM
326         /*
327          * A memory area that is only addressable by the kernel through
328          * mapping portions into its own address space. This is for example
329          * used by i386 to allow the kernel to address the memory beyond
330          * 900MB. The kernel will set up special mappings (page
331          * table entries on i386) for each page that the kernel needs to
332          * access.
333          */
334         ZONE_HIGHMEM,
335 #endif
336         ZONE_MOVABLE,
337 #ifdef CONFIG_ZONE_DEVICE
338         ZONE_DEVICE,
339 #endif
340         __MAX_NR_ZONES
341 
342 };
343 
344 #ifndef __GENERATING_BOUNDS_H
345 
346 struct zone {
347         /* Read-mostly fields */
348 
349         /* zone watermarks, access with *_wmark_pages(zone) macros */
350         unsigned long watermark[NR_WMARK];
351 
352         unsigned long nr_reserved_highatomic;
353 
354         /*
355          * We don't know if the memory that we're going to allocate will be
356          * freeable or/and it will be released eventually, so to avoid totally
357          * wasting several GB of ram we must reserve some of the lower zone
358          * memory (otherwise we risk to run OOM on the lower zones despite
359          * there being tons of freeable ram on the higher zones).  This array is
360          * recalculated at runtime if the sysctl_lowmem_reserve_ratio sysctl
361          * changes.
362          */
363         long lowmem_reserve[MAX_NR_ZONES];
364 
365 #ifdef CONFIG_NUMA
366         int node;
367 #endif
368         struct pglist_data      *zone_pgdat;
369         struct per_cpu_pageset __percpu *pageset;
370 
371 #ifndef CONFIG_SPARSEMEM
372         /*
373          * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
374          * In SPARSEMEM, this map is stored in struct mem_section
375          */
376         unsigned long           *pageblock_flags;
377 #endif /* CONFIG_SPARSEMEM */
378 
379         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
380         unsigned long           zone_start_pfn;
381 
382         /*
383          * spanned_pages is the total pages spanned by the zone, including
384          * holes, which is calculated as:
385          *      spanned_pages = zone_end_pfn - zone_start_pfn;
386          *
387          * present_pages is physical pages existing within the zone, which
388          * is calculated as:
389          *      present_pages = spanned_pages - absent_pages(pages in holes);
390          *
391          * managed_pages is present pages managed by the buddy system, which
392          * is calculated as (reserved_pages includes pages allocated by the
393          * bootmem allocator):
394          *      managed_pages = present_pages - reserved_pages;
395          *
396          * So present_pages may be used by memory hotplug or memory power
397          * management logic to figure out unmanaged pages by checking
398          * (present_pages - managed_pages). And managed_pages should be used
399          * by page allocator and vm scanner to calculate all kinds of watermarks
400          * and thresholds.
401          *
402          * Locking rules:
403          *
404          * zone_start_pfn and spanned_pages are protected by span_seqlock.
405          * It is a seqlock because it has to be read outside of zone->lock,
406          * and it is done in the main allocator path.  But, it is written
407          * quite infrequently.
408          *
409          * The span_seq lock is declared along with zone->lock because it is
410          * frequently read in proximity to zone->lock.  It's good to
411          * give them a chance of being in the same cacheline.
412          *
413          * Write access to present_pages at runtime should be protected by
414          * mem_hotplug_begin/end(). Any reader who can't tolerant drift of
415          * present_pages should get_online_mems() to get a stable value.
416          *
417          * Read access to managed_pages should be safe because it's unsigned
418          * long. Write access to zone->managed_pages and totalram_pages are
419          * protected by managed_page_count_lock at runtime. Idealy only
420          * adjust_managed_page_count() should be used instead of directly
421          * touching zone->managed_pages and totalram_pages.
422          */
423         unsigned long           managed_pages;
424         unsigned long           spanned_pages;
425         unsigned long           present_pages;
426 
427         const char              *name;
428 
429 #ifdef CONFIG_MEMORY_ISOLATION
430         /*
431          * Number of isolated pageblock. It is used to solve incorrect
432          * freepage counting problem due to racy retrieving migratetype
433          * of pageblock. Protected by zone->lock.
434          */
435         unsigned long           nr_isolate_pageblock;
436 #endif
437 
438 #ifdef CONFIG_MEMORY_HOTPLUG
439         /* see spanned/present_pages for more description */
440         seqlock_t               span_seqlock;
441 #endif
442 
443         /*
444          * wait_table           -- the array holding the hash table
445          * wait_table_hash_nr_entries   -- the size of the hash table array
446          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
447          *
448          * The purpose of all these is to keep track of the people
449          * waiting for a page to become available and make them
450          * runnable again when possible. The trouble is that this
451          * consumes a lot of space, especially when so few things
452          * wait on pages at a given time. So instead of using
453          * per-page waitqueues, we use a waitqueue hash table.
454          *
455          * The bucket discipline is to sleep on the same queue when
456          * colliding and wake all in that wait queue when removing.
457          * When something wakes, it must check to be sure its page is
458          * truly available, a la thundering herd. The cost of a
459          * collision is great, but given the expected load of the
460          * table, they should be so rare as to be outweighed by the
461          * benefits from the saved space.
462          *
463          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
464          * primary users of these fields, and in mm/page_alloc.c
465          * free_area_init_core() performs the initialization of them.
466          */
467         wait_queue_head_t       *wait_table;
468         unsigned long           wait_table_hash_nr_entries;
469         unsigned long           wait_table_bits;
470 
471         /* Write-intensive fields used from the page allocator */
472         ZONE_PADDING(_pad1_)
473 
474         /* free areas of different sizes */
475         struct free_area        free_area[MAX_ORDER];
476 
477         /* zone flags, see below */
478         unsigned long           flags;
479 
480         /* Primarily protects free_area */
481         spinlock_t              lock;
482 
483         /* Write-intensive fields used by compaction and vmstats. */
484         ZONE_PADDING(_pad2_)
485 
486         /*
487          * When free pages are below this point, additional steps are taken
488          * when reading the number of free pages to avoid per-cpu counter
489          * drift allowing watermarks to be breached
490          */
491         unsigned long percpu_drift_mark;
492 
493 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
494         /* pfn where compaction free scanner should start */
495         unsigned long           compact_cached_free_pfn;
496         /* pfn where async and sync compaction migration scanner should start */
497         unsigned long           compact_cached_migrate_pfn[2];
498 #endif
499 
500 #ifdef CONFIG_COMPACTION
501         /*
502          * On compaction failure, 1<<compact_defer_shift compactions
503          * are skipped before trying again. The number attempted since
504          * last failure is tracked with compact_considered.
505          */
506         unsigned int            compact_considered;
507         unsigned int            compact_defer_shift;
508         int                     compact_order_failed;
509 #endif
510 
511 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
512         /* Set to true when the PG_migrate_skip bits should be cleared */
513         bool                    compact_blockskip_flush;
514 #endif
515 
516         bool                    contiguous;
517 
518         ZONE_PADDING(_pad3_)
519         /* Zone statistics */
520         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
521 } ____cacheline_internodealigned_in_smp;
522 
523 enum pgdat_flags {
524         PGDAT_CONGESTED,                /* pgdat has many dirty pages backed by
525                                          * a congested BDI
526                                          */
527         PGDAT_DIRTY,                    /* reclaim scanning has recently found
528                                          * many dirty file pages at the tail
529                                          * of the LRU.
530                                          */
531         PGDAT_WRITEBACK,                /* reclaim scanning has recently found
532                                          * many pages under writeback
533                                          */
534         PGDAT_RECLAIM_LOCKED,           /* prevents concurrent reclaim */
535 };
536 
537 static inline unsigned long zone_end_pfn(const struct zone *zone)
538 {
539         return zone->zone_start_pfn + zone->spanned_pages;
540 }
541 
542 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
543 {
544         return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
545 }
546 
547 static inline bool zone_is_initialized(struct zone *zone)
548 {
549         return !!zone->wait_table;
550 }
551 
552 static inline bool zone_is_empty(struct zone *zone)
553 {
554         return zone->spanned_pages == 0;
555 }
556 
557 /*
558  * The "priority" of VM scanning is how much of the queues we will scan in one
559  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
560  * queues ("queue_length >> 12") during an aging round.
561  */
562 #define DEF_PRIORITY 12
563 
564 /* Maximum number of zones on a zonelist */
565 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
566 
567 enum {
568         ZONELIST_FALLBACK,      /* zonelist with fallback */
569 #ifdef CONFIG_NUMA
570         /*
571          * The NUMA zonelists are doubled because we need zonelists that
572          * restrict the allocations to a single node for __GFP_THISNODE.
573          */
574         ZONELIST_NOFALLBACK,    /* zonelist without fallback (__GFP_THISNODE) */
575 #endif
576         MAX_ZONELISTS
577 };
578 
579 /*
580  * This struct contains information about a zone in a zonelist. It is stored
581  * here to avoid dereferences into large structures and lookups of tables
582  */
583 struct zoneref {
584         struct zone *zone;      /* Pointer to actual zone */
585         int zone_idx;           /* zone_idx(zoneref->zone) */
586 };
587 
588 /*
589  * One allocation request operates on a zonelist. A zonelist
590  * is a list of zones, the first one is the 'goal' of the
591  * allocation, the other zones are fallback zones, in decreasing
592  * priority.
593  *
594  * To speed the reading of the zonelist, the zonerefs contain the zone index
595  * of the entry being read. Helper functions to access information given
596  * a struct zoneref are
597  *
598  * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
599  * zonelist_zone_idx()  - Return the index of the zone for an entry
600  * zonelist_node_idx()  - Return the index of the node for an entry
601  */
602 struct zonelist {
603         struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
604 };
605 
606 #ifndef CONFIG_DISCONTIGMEM
607 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
608 extern struct page *mem_map;
609 #endif
610 
611 /*
612  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
613  * (mostly NUMA machines?) to denote a higher-level memory zone than the
614  * zone denotes.
615  *
616  * On NUMA machines, each NUMA node would have a pg_data_t to describe
617  * it's memory layout.
618  *
619  * Memory statistics and page replacement data structures are maintained on a
620  * per-zone basis.
621  */
622 struct bootmem_data;
623 typedef struct pglist_data {
624         struct zone node_zones[MAX_NR_ZONES];
625         struct zonelist node_zonelists[MAX_ZONELISTS];
626         int nr_zones;
627 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
628         struct page *node_mem_map;
629 #ifdef CONFIG_PAGE_EXTENSION
630         struct page_ext *node_page_ext;
631 #endif
632 #endif
633 #ifndef CONFIG_NO_BOOTMEM
634         struct bootmem_data *bdata;
635 #endif
636 #ifdef CONFIG_MEMORY_HOTPLUG
637         /*
638          * Must be held any time you expect node_start_pfn, node_present_pages
639          * or node_spanned_pages stay constant.  Holding this will also
640          * guarantee that any pfn_valid() stays that way.
641          *
642          * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
643          * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG.
644          *
645          * Nests above zone->lock and zone->span_seqlock
646          */
647         spinlock_t node_size_lock;
648 #endif
649         unsigned long node_start_pfn;
650         unsigned long node_present_pages; /* total number of physical pages */
651         unsigned long node_spanned_pages; /* total size of physical page
652                                              range, including holes */
653         int node_id;
654         wait_queue_head_t kswapd_wait;
655         wait_queue_head_t pfmemalloc_wait;
656         struct task_struct *kswapd;     /* Protected by
657                                            mem_hotplug_begin/end() */
658         int kswapd_order;
659         enum zone_type kswapd_classzone_idx;
660 
661 #ifdef CONFIG_COMPACTION
662         int kcompactd_max_order;
663         enum zone_type kcompactd_classzone_idx;
664         wait_queue_head_t kcompactd_wait;
665         struct task_struct *kcompactd;
666 #endif
667 #ifdef CONFIG_NUMA_BALANCING
668         /* Lock serializing the migrate rate limiting window */
669         spinlock_t numabalancing_migrate_lock;
670 
671         /* Rate limiting time interval */
672         unsigned long numabalancing_migrate_next_window;
673 
674         /* Number of pages migrated during the rate limiting time interval */
675         unsigned long numabalancing_migrate_nr_pages;
676 #endif
677         /*
678          * This is a per-node reserve of pages that are not available
679          * to userspace allocations.
680          */
681         unsigned long           totalreserve_pages;
682 
683 #ifdef CONFIG_NUMA
684         /*
685          * zone reclaim becomes active if more unmapped pages exist.
686          */
687         unsigned long           min_unmapped_pages;
688         unsigned long           min_slab_pages;
689 #endif /* CONFIG_NUMA */
690 
691         /* Write-intensive fields used by page reclaim */
692         ZONE_PADDING(_pad1_)
693         spinlock_t              lru_lock;
694 
695 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
696         /*
697          * If memory initialisation on large machines is deferred then this
698          * is the first PFN that needs to be initialised.
699          */
700         unsigned long first_deferred_pfn;
701 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
702 
703 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
704         spinlock_t split_queue_lock;
705         struct list_head split_queue;
706         unsigned long split_queue_len;
707 #endif
708 
709         /* Fields commonly accessed by the page reclaim scanner */
710         struct lruvec           lruvec;
711 
712         /*
713          * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
714          * this node's LRU.  Maintained by the pageout code.
715          */
716         unsigned int inactive_ratio;
717 
718         unsigned long           flags;
719 
720         ZONE_PADDING(_pad2_)
721 
722         /* Per-node vmstats */
723         struct per_cpu_nodestat __percpu *per_cpu_nodestats;
724         atomic_long_t           vm_stat[NR_VM_NODE_STAT_ITEMS];
725 } pg_data_t;
726 
727 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
728 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
729 #ifdef CONFIG_FLAT_NODE_MEM_MAP
730 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
731 #else
732 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
733 #endif
734 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
735 
736 #define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
737 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
738 static inline spinlock_t *zone_lru_lock(struct zone *zone)
739 {
740         return &zone->zone_pgdat->lru_lock;
741 }
742 
743 static inline struct lruvec *node_lruvec(struct pglist_data *pgdat)
744 {
745         return &pgdat->lruvec;
746 }
747 
748 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
749 {
750         return pgdat->node_start_pfn + pgdat->node_spanned_pages;
751 }
752 
753 static inline bool pgdat_is_empty(pg_data_t *pgdat)
754 {
755         return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
756 }
757 
758 static inline int zone_id(const struct zone *zone)
759 {
760         struct pglist_data *pgdat = zone->zone_pgdat;
761 
762         return zone - pgdat->node_zones;
763 }
764 
765 #ifdef CONFIG_ZONE_DEVICE
766 static inline bool is_dev_zone(const struct zone *zone)
767 {
768         return zone_id(zone) == ZONE_DEVICE;
769 }
770 #else
771 static inline bool is_dev_zone(const struct zone *zone)
772 {
773         return false;
774 }
775 #endif
776 
777 #include <linux/memory_hotplug.h>
778 
779 extern struct mutex zonelists_mutex;
780 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
781 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
782 bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
783                          int classzone_idx, unsigned int alloc_flags,
784                          long free_pages);
785 bool zone_watermark_ok(struct zone *z, unsigned int order,
786                 unsigned long mark, int classzone_idx,
787                 unsigned int alloc_flags);
788 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
789                 unsigned long mark, int classzone_idx);
790 enum memmap_context {
791         MEMMAP_EARLY,
792         MEMMAP_HOTPLUG,
793 };
794 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
795                                      unsigned long size);
796 
797 extern void lruvec_init(struct lruvec *lruvec);
798 
799 static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
800 {
801 #ifdef CONFIG_MEMCG
802         return lruvec->pgdat;
803 #else
804         return container_of(lruvec, struct pglist_data, lruvec);
805 #endif
806 }
807 
808 extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
809 
810 #ifdef CONFIG_HAVE_MEMORY_PRESENT
811 void memory_present(int nid, unsigned long start, unsigned long end);
812 #else
813 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
814 #endif
815 
816 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
817 int local_memory_node(int node_id);
818 #else
819 static inline int local_memory_node(int node_id) { return node_id; };
820 #endif
821 
822 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
823 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
824 #endif
825 
826 /*
827  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
828  */
829 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
830 
831 /*
832  * Returns true if a zone has pages managed by the buddy allocator.
833  * All the reclaim decisions have to use this function rather than
834  * populated_zone(). If the whole zone is reserved then we can easily
835  * end up with populated_zone() && !managed_zone().
836  */
837 static inline bool managed_zone(struct zone *zone)
838 {
839         return zone->managed_pages;
840 }
841 
842 /* Returns true if a zone has memory */
843 static inline bool populated_zone(struct zone *zone)
844 {
845         return zone->present_pages;
846 }
847 
848 extern int movable_zone;
849 
850 #ifdef CONFIG_HIGHMEM
851 static inline int zone_movable_is_highmem(void)
852 {
853 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
854         return movable_zone == ZONE_HIGHMEM;
855 #else
856         return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM;
857 #endif
858 }
859 #endif
860 
861 static inline int is_highmem_idx(enum zone_type idx)
862 {
863 #ifdef CONFIG_HIGHMEM
864         return (idx == ZONE_HIGHMEM ||
865                 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
866 #else
867         return 0;
868 #endif
869 }
870 
871 /**
872  * is_highmem - helper function to quickly check if a struct zone is a 
873  *              highmem zone or not.  This is an attempt to keep references
874  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
875  * @zone - pointer to struct zone variable
876  */
877 static inline int is_highmem(struct zone *zone)
878 {
879 #ifdef CONFIG_HIGHMEM
880         return is_highmem_idx(zone_idx(zone));
881 #else
882         return 0;
883 #endif
884 }
885 
886 /* These two functions are used to setup the per zone pages min values */
887 struct ctl_table;
888 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
889                                         void __user *, size_t *, loff_t *);
890 int watermark_scale_factor_sysctl_handler(struct ctl_table *, int,
891                                         void __user *, size_t *, loff_t *);
892 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
893 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
894                                         void __user *, size_t *, loff_t *);
895 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
896                                         void __user *, size_t *, loff_t *);
897 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
898                         void __user *, size_t *, loff_t *);
899 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
900                         void __user *, size_t *, loff_t *);
901 
902 extern int numa_zonelist_order_handler(struct ctl_table *, int,
903                         void __user *, size_t *, loff_t *);
904 extern char numa_zonelist_order[];
905 #define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
906 
907 #ifndef CONFIG_NEED_MULTIPLE_NODES
908 
909 extern struct pglist_data contig_page_data;
910 #define NODE_DATA(nid)          (&contig_page_data)
911 #define NODE_MEM_MAP(nid)       mem_map
912 
913 #else /* CONFIG_NEED_MULTIPLE_NODES */
914 
915 #include <asm/mmzone.h>
916 
917 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
918 
919 extern struct pglist_data *first_online_pgdat(void);
920 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
921 extern struct zone *next_zone(struct zone *zone);
922 
923 /**
924  * for_each_online_pgdat - helper macro to iterate over all online nodes
925  * @pgdat - pointer to a pg_data_t variable
926  */
927 #define for_each_online_pgdat(pgdat)                    \
928         for (pgdat = first_online_pgdat();              \
929              pgdat;                                     \
930              pgdat = next_online_pgdat(pgdat))
931 /**
932  * for_each_zone - helper macro to iterate over all memory zones
933  * @zone - pointer to struct zone variable
934  *
935  * The user only needs to declare the zone variable, for_each_zone
936  * fills it in.
937  */
938 #define for_each_zone(zone)                             \
939         for (zone = (first_online_pgdat())->node_zones; \
940              zone;                                      \
941              zone = next_zone(zone))
942 
943 #define for_each_populated_zone(zone)                   \
944         for (zone = (first_online_pgdat())->node_zones; \
945              zone;                                      \
946              zone = next_zone(zone))                    \
947                 if (!populated_zone(zone))              \
948                         ; /* do nothing */              \
949                 else
950 
951 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
952 {
953         return zoneref->zone;
954 }
955 
956 static inline int zonelist_zone_idx(struct zoneref *zoneref)
957 {
958         return zoneref->zone_idx;
959 }
960 
961 static inline int zonelist_node_idx(struct zoneref *zoneref)
962 {
963 #ifdef CONFIG_NUMA
964         /* zone_to_nid not available in this context */
965         return zoneref->zone->node;
966 #else
967         return 0;
968 #endif /* CONFIG_NUMA */
969 }
970 
971 struct zoneref *__next_zones_zonelist(struct zoneref *z,
972                                         enum zone_type highest_zoneidx,
973                                         nodemask_t *nodes);
974 
975 /**
976  * next_zones_zonelist - Returns the next zone at or below highest_zoneidx within the allowed nodemask using a cursor within a zonelist as a starting point
977  * @z - The cursor used as a starting point for the search
978  * @highest_zoneidx - The zone index of the highest zone to return
979  * @nodes - An optional nodemask to filter the zonelist with
980  *
981  * This function returns the next zone at or below a given zone index that is
982  * within the allowed nodemask using a cursor as the starting point for the
983  * search. The zoneref returned is a cursor that represents the current zone
984  * being examined. It should be advanced by one before calling
985  * next_zones_zonelist again.
986  */
987 static __always_inline struct zoneref *next_zones_zonelist(struct zoneref *z,
988                                         enum zone_type highest_zoneidx,
989                                         nodemask_t *nodes)
990 {
991         if (likely(!nodes && zonelist_zone_idx(z) <= highest_zoneidx))
992                 return z;
993         return __next_zones_zonelist(z, highest_zoneidx, nodes);
994 }
995 
996 /**
997  * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
998  * @zonelist - The zonelist to search for a suitable zone
999  * @highest_zoneidx - The zone index of the highest zone to return
1000  * @nodes - An optional nodemask to filter the zonelist with
1001  * @zone - The first suitable zone found is returned via this parameter
1002  *
1003  * This function returns the first zone at or below a given zone index that is
1004  * within the allowed nodemask. The zoneref returned is a cursor that can be
1005  * used to iterate the zonelist with next_zones_zonelist by advancing it by
1006  * one before calling.
1007  */
1008 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
1009                                         enum zone_type highest_zoneidx,
1010                                         nodemask_t *nodes)
1011 {
1012         return next_zones_zonelist(zonelist->_zonerefs,
1013                                                         highest_zoneidx, nodes);
1014 }
1015 
1016 /**
1017  * 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
1018  * @zone - The current zone in the iterator
1019  * @z - The current pointer within zonelist->zones being iterated
1020  * @zlist - The zonelist being iterated
1021  * @highidx - The zone index of the highest zone to return
1022  * @nodemask - Nodemask allowed by the allocator
1023  *
1024  * This iterator iterates though all zones at or below a given zone index and
1025  * within a given nodemask
1026  */
1027 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1028         for (z = first_zones_zonelist(zlist, highidx, nodemask), zone = zonelist_zone(z);       \
1029                 zone;                                                   \
1030                 z = next_zones_zonelist(++z, highidx, nodemask),        \
1031                         zone = zonelist_zone(z))
1032 
1033 #define for_next_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1034         for (zone = z->zone;    \
1035                 zone;                                                   \
1036                 z = next_zones_zonelist(++z, highidx, nodemask),        \
1037                         zone = zonelist_zone(z))
1038 
1039 
1040 /**
1041  * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1042  * @zone - The current zone in the iterator
1043  * @z - The current pointer within zonelist->zones being iterated
1044  * @zlist - The zonelist being iterated
1045  * @highidx - The zone index of the highest zone to return
1046  *
1047  * This iterator iterates though all zones at or below a given zone index.
1048  */
1049 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1050         for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1051 
1052 #ifdef CONFIG_SPARSEMEM
1053 #include <asm/sparsemem.h>
1054 #endif
1055 
1056 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1057         !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1058 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1059 {
1060         return 0;
1061 }
1062 #endif
1063 
1064 #ifdef CONFIG_FLATMEM
1065 #define pfn_to_nid(pfn)         (0)
1066 #endif
1067 
1068 #ifdef CONFIG_SPARSEMEM
1069 
1070 /*
1071  * SECTION_SHIFT                #bits space required to store a section #
1072  *
1073  * PA_SECTION_SHIFT             physical address to/from section number
1074  * PFN_SECTION_SHIFT            pfn to/from section number
1075  */
1076 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1077 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1078 
1079 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1080 
1081 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1082 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1083 
1084 #define SECTION_BLOCKFLAGS_BITS \
1085         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1086 
1087 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1088 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1089 #endif
1090 
1091 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1092 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1093 
1094 #define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1095 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1096 
1097 struct page;
1098 struct page_ext;
1099 struct mem_section {
1100         /*
1101          * This is, logically, a pointer to an array of struct
1102          * pages.  However, it is stored with some other magic.
1103          * (see sparse.c::sparse_init_one_section())
1104          *
1105          * Additionally during early boot we encode node id of
1106          * the location of the section here to guide allocation.
1107          * (see sparse.c::memory_present())
1108          *
1109          * Making it a UL at least makes someone do a cast
1110          * before using it wrong.
1111          */
1112         unsigned long section_mem_map;
1113 
1114         /* See declaration of similar field in struct zone */
1115         unsigned long *pageblock_flags;
1116 #ifdef CONFIG_PAGE_EXTENSION
1117         /*
1118          * If SPARSEMEM, pgdat doesn't have page_ext pointer. We use
1119          * section. (see page_ext.h about this.)
1120          */
1121         struct page_ext *page_ext;
1122         unsigned long pad;
1123 #endif
1124         /*
1125          * WARNING: mem_section must be a power-of-2 in size for the
1126          * calculation and use of SECTION_ROOT_MASK to make sense.
1127          */
1128 };
1129 
1130 #ifdef CONFIG_SPARSEMEM_EXTREME
1131 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1132 #else
1133 #define SECTIONS_PER_ROOT       1
1134 #endif
1135 
1136 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1137 #define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1138 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1139 
1140 #ifdef CONFIG_SPARSEMEM_EXTREME
1141 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1142 #else
1143 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1144 #endif
1145 
1146 static inline struct mem_section *__nr_to_section(unsigned long nr)
1147 {
1148         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1149                 return NULL;
1150         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1151 }
1152 extern int __section_nr(struct mem_section* ms);
1153 extern unsigned long usemap_size(void);
1154 
1155 /*
1156  * We use the lower bits of the mem_map pointer to store
1157  * a little bit of information.  There should be at least
1158  * 3 bits here due to 32-bit alignment.
1159  */
1160 #define SECTION_MARKED_PRESENT  (1UL<<0)
1161 #define SECTION_HAS_MEM_MAP     (1UL<<1)
1162 #define SECTION_MAP_LAST_BIT    (1UL<<2)
1163 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1164 #define SECTION_NID_SHIFT       2
1165 
1166 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1167 {
1168         unsigned long map = section->section_mem_map;
1169         map &= SECTION_MAP_MASK;
1170         return (struct page *)map;
1171 }
1172 
1173 static inline int present_section(struct mem_section *section)
1174 {
1175         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1176 }
1177 
1178 static inline int present_section_nr(unsigned long nr)
1179 {
1180         return present_section(__nr_to_section(nr));
1181 }
1182 
1183 static inline int valid_section(struct mem_section *section)
1184 {
1185         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1186 }
1187 
1188 static inline int valid_section_nr(unsigned long nr)
1189 {
1190         return valid_section(__nr_to_section(nr));
1191 }
1192 
1193 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1194 {
1195         return __nr_to_section(pfn_to_section_nr(pfn));
1196 }
1197 
1198 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1199 static inline int pfn_valid(unsigned long pfn)
1200 {
1201         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1202                 return 0;
1203         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1204 }
1205 #endif
1206 
1207 static inline int pfn_present(unsigned long pfn)
1208 {
1209         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1210                 return 0;
1211         return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1212 }
1213 
1214 /*
1215  * These are _only_ used during initialisation, therefore they
1216  * can use __initdata ...  They could have names to indicate
1217  * this restriction.
1218  */
1219 #ifdef CONFIG_NUMA
1220 #define pfn_to_nid(pfn)                                                 \
1221 ({                                                                      \
1222         unsigned long __pfn_to_nid_pfn = (pfn);                         \
1223         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1224 })
1225 #else
1226 #define pfn_to_nid(pfn)         (0)
1227 #endif
1228 
1229 #define early_pfn_valid(pfn)    pfn_valid(pfn)
1230 void sparse_init(void);
1231 #else
1232 #define sparse_init()   do {} while (0)
1233 #define sparse_index_init(_sec, _nid)  do {} while (0)
1234 #endif /* CONFIG_SPARSEMEM */
1235 
1236 /*
1237  * During memory init memblocks map pfns to nids. The search is expensive and
1238  * this caches recent lookups. The implementation of __early_pfn_to_nid
1239  * may treat start/end as pfns or sections.
1240  */
1241 struct mminit_pfnnid_cache {
1242         unsigned long last_start;
1243         unsigned long last_end;
1244         int last_nid;
1245 };
1246 
1247 #ifndef early_pfn_valid
1248 #define early_pfn_valid(pfn)    (1)
1249 #endif
1250 
1251 void memory_present(int nid, unsigned long start, unsigned long end);
1252 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1253 
1254 /*
1255  * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1256  * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1257  * pfn_valid_within() should be used in this case; we optimise this away
1258  * when we have no holes within a MAX_ORDER_NR_PAGES block.
1259  */
1260 #ifdef CONFIG_HOLES_IN_ZONE
1261 #define pfn_valid_within(pfn) pfn_valid(pfn)
1262 #else
1263 #define pfn_valid_within(pfn) (1)
1264 #endif
1265 
1266 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1267 /*
1268  * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1269  * associated with it or not. In FLATMEM, it is expected that holes always
1270  * have valid memmap as long as there is valid PFNs either side of the hole.
1271  * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1272  * entire section.
1273  *
1274  * However, an ARM, and maybe other embedded architectures in the future
1275  * free memmap backing holes to save memory on the assumption the memmap is
1276  * never used. The page_zone linkages are then broken even though pfn_valid()
1277  * returns true. A walker of the full memmap must then do this additional
1278  * check to ensure the memmap they are looking at is sane by making sure
1279  * the zone and PFN linkages are still valid. This is expensive, but walkers
1280  * of the full memmap are extremely rare.
1281  */
1282 bool memmap_valid_within(unsigned long pfn,
1283                                         struct page *page, struct zone *zone);
1284 #else
1285 static inline bool memmap_valid_within(unsigned long pfn,
1286                                         struct page *page, struct zone *zone)
1287 {
1288         return true;
1289 }
1290 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1291 
1292 #endif /* !__GENERATING_BOUNDS.H */
1293 #endif /* !__ASSEMBLY__ */
1294 #endif /* _LINUX_MMZONE_H */
1295 

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