Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

Linux/include/linux/mmzone.h

  1 #ifndef _LINUX_MMZONE_H
  2 #define _LINUX_MMZONE_H
  3 
  4 #ifndef __ASSEMBLY__
  5 #ifndef __GENERATING_BOUNDS_H
  6 
  7 #include <linux/spinlock.h>
  8 #include <linux/list.h>
  9 #include <linux/wait.h>
 10 #include <linux/bitops.h>
 11 #include <linux/cache.h>
 12 #include <linux/threads.h>
 13 #include <linux/numa.h>
 14 #include <linux/init.h>
 15 #include <linux/seqlock.h>
 16 #include <linux/nodemask.h>
 17 #include <linux/pageblock-flags.h>
 18 #include <linux/page-flags-layout.h>
 19 #include <linux/atomic.h>
 20 #include <asm/page.h>
 21 
 22 /* Free memory management - zoned buddy allocator.  */
 23 #ifndef CONFIG_FORCE_MAX_ZONEORDER
 24 #define MAX_ORDER 11
 25 #else
 26 #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
 27 #endif
 28 #define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1))
 29 
 30 /*
 31  * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
 32  * costly to service.  That is between allocation orders which should
 33  * coalesce naturally under reasonable reclaim pressure and those which
 34  * will not.
 35  */
 36 #define PAGE_ALLOC_COSTLY_ORDER 3
 37 
 38 enum {
 39         MIGRATE_UNMOVABLE,
 40         MIGRATE_RECLAIMABLE,
 41         MIGRATE_MOVABLE,
 42         MIGRATE_PCPTYPES,       /* the number of types on the pcp lists */
 43         MIGRATE_RESERVE = MIGRATE_PCPTYPES,
 44 #ifdef CONFIG_CMA
 45         /*
 46          * MIGRATE_CMA migration type is designed to mimic the way
 47          * ZONE_MOVABLE works.  Only movable pages can be allocated
 48          * from MIGRATE_CMA pageblocks and page allocator never
 49          * implicitly change migration type of MIGRATE_CMA pageblock.
 50          *
 51          * The way to use it is to change migratetype of a range of
 52          * pageblocks to MIGRATE_CMA which can be done by
 53          * __free_pageblock_cma() function.  What is important though
 54          * is that a range of pageblocks must be aligned to
 55          * MAX_ORDER_NR_PAGES should biggest page be bigger then
 56          * a single pageblock.
 57          */
 58         MIGRATE_CMA,
 59 #endif
 60 #ifdef CONFIG_MEMORY_ISOLATION
 61         MIGRATE_ISOLATE,        /* can't allocate from here */
 62 #endif
 63         MIGRATE_TYPES
 64 };
 65 
 66 #ifdef CONFIG_CMA
 67 #  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
 68 #else
 69 #  define is_migrate_cma(migratetype) false
 70 #endif
 71 
 72 #define for_each_migratetype_order(order, type) \
 73         for (order = 0; order < MAX_ORDER; order++) \
 74                 for (type = 0; type < MIGRATE_TYPES; type++)
 75 
 76 extern int page_group_by_mobility_disabled;
 77 
 78 static inline int get_pageblock_migratetype(struct page *page)
 79 {
 80         return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
 81 }
 82 
 83 struct free_area {
 84         struct list_head        free_list[MIGRATE_TYPES];
 85         unsigned long           nr_free;
 86 };
 87 
 88 struct pglist_data;
 89 
 90 /*
 91  * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
 92  * So add a wild amount of padding here to ensure that they fall into separate
 93  * cachelines.  There are very few zone structures in the machine, so space
 94  * consumption is not a concern here.
 95  */
 96 #if defined(CONFIG_SMP)
 97 struct zone_padding {
 98         char x[0];
 99 } ____cacheline_internodealigned_in_smp;
100 #define ZONE_PADDING(name)      struct zone_padding name;
101 #else
102 #define ZONE_PADDING(name)
103 #endif
104 
105 enum zone_stat_item {
106         /* First 128 byte cacheline (assuming 64 bit words) */
107         NR_FREE_PAGES,
108         NR_ALLOC_BATCH,
109         NR_LRU_BASE,
110         NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
111         NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
112         NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
113         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
114         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
115         NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
116         NR_ANON_PAGES,  /* Mapped anonymous pages */
117         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
118                            only modified from process context */
119         NR_FILE_PAGES,
120         NR_FILE_DIRTY,
121         NR_WRITEBACK,
122         NR_SLAB_RECLAIMABLE,
123         NR_SLAB_UNRECLAIMABLE,
124         NR_PAGETABLE,           /* used for pagetables */
125         NR_KERNEL_STACK,
126         /* Second 128 byte cacheline */
127         NR_UNSTABLE_NFS,        /* NFS unstable pages */
128         NR_BOUNCE,
129         NR_VMSCAN_WRITE,
130         NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
131         NR_WRITEBACK_TEMP,      /* Writeback using temporary buffers */
132         NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
133         NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
134         NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
135         NR_DIRTIED,             /* page dirtyings since bootup */
136         NR_WRITTEN,             /* page writings since bootup */
137 #ifdef CONFIG_NUMA
138         NUMA_HIT,               /* allocated in intended node */
139         NUMA_MISS,              /* allocated in non intended node */
140         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
141         NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
142         NUMA_LOCAL,             /* allocation from local node */
143         NUMA_OTHER,             /* allocation from other node */
144 #endif
145         WORKINGSET_REFAULT,
146         WORKINGSET_ACTIVATE,
147         WORKINGSET_NODERECLAIM,
148         NR_ANON_TRANSPARENT_HUGEPAGES,
149         NR_FREE_CMA_PAGES,
150         NR_VM_ZONE_STAT_ITEMS };
151 
152 /*
153  * We do arithmetic on the LRU lists in various places in the code,
154  * so it is important to keep the active lists LRU_ACTIVE higher in
155  * the array than the corresponding inactive lists, and to keep
156  * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
157  *
158  * This has to be kept in sync with the statistics in zone_stat_item
159  * above and the descriptions in vmstat_text in mm/vmstat.c
160  */
161 #define LRU_BASE 0
162 #define LRU_ACTIVE 1
163 #define LRU_FILE 2
164 
165 enum lru_list {
166         LRU_INACTIVE_ANON = LRU_BASE,
167         LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
168         LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
169         LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
170         LRU_UNEVICTABLE,
171         NR_LRU_LISTS
172 };
173 
174 #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
175 
176 #define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
177 
178 static inline int is_file_lru(enum lru_list lru)
179 {
180         return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
181 }
182 
183 static inline int is_active_lru(enum lru_list lru)
184 {
185         return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
186 }
187 
188 static inline int is_unevictable_lru(enum lru_list lru)
189 {
190         return (lru == LRU_UNEVICTABLE);
191 }
192 
193 struct zone_reclaim_stat {
194         /*
195          * The pageout code in vmscan.c keeps track of how many of the
196          * mem/swap backed and file backed pages are referenced.
197          * The higher the rotated/scanned ratio, the more valuable
198          * that cache is.
199          *
200          * The anon LRU stats live in [0], file LRU stats in [1]
201          */
202         unsigned long           recent_rotated[2];
203         unsigned long           recent_scanned[2];
204 };
205 
206 struct lruvec {
207         struct list_head lists[NR_LRU_LISTS];
208         struct zone_reclaim_stat reclaim_stat;
209 #ifdef CONFIG_MEMCG
210         struct zone *zone;
211 #endif
212 };
213 
214 /* Mask used at gathering information at once (see memcontrol.c) */
215 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
216 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
217 #define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
218 
219 /* Isolate clean file */
220 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
221 /* Isolate unmapped file */
222 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
223 /* Isolate for asynchronous migration */
224 #define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
225 /* Isolate unevictable pages */
226 #define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
227 
228 /* LRU Isolation modes. */
229 typedef unsigned __bitwise__ isolate_mode_t;
230 
231 enum zone_watermarks {
232         WMARK_MIN,
233         WMARK_LOW,
234         WMARK_HIGH,
235         NR_WMARK
236 };
237 
238 #define min_wmark_pages(z) (z->watermark[WMARK_MIN])
239 #define low_wmark_pages(z) (z->watermark[WMARK_LOW])
240 #define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
241 
242 struct per_cpu_pages {
243         int count;              /* number of pages in the list */
244         int high;               /* high watermark, emptying needed */
245         int batch;              /* chunk size for buddy add/remove */
246 
247         /* Lists of pages, one per migrate type stored on the pcp-lists */
248         struct list_head lists[MIGRATE_PCPTYPES];
249 };
250 
251 struct per_cpu_pageset {
252         struct per_cpu_pages pcp;
253 #ifdef CONFIG_NUMA
254         s8 expire;
255 #endif
256 #ifdef CONFIG_SMP
257         s8 stat_threshold;
258         s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
259 #endif
260 };
261 
262 #endif /* !__GENERATING_BOUNDS.H */
263 
264 enum zone_type {
265 #ifdef CONFIG_ZONE_DMA
266         /*
267          * ZONE_DMA is used when there are devices that are not able
268          * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
269          * carve out the portion of memory that is needed for these devices.
270          * The range is arch specific.
271          *
272          * Some examples
273          *
274          * Architecture         Limit
275          * ---------------------------
276          * parisc, ia64, sparc  <4G
277          * s390                 <2G
278          * arm                  Various
279          * alpha                Unlimited or 0-16MB.
280          *
281          * i386, x86_64 and multiple other arches
282          *                      <16M.
283          */
284         ZONE_DMA,
285 #endif
286 #ifdef CONFIG_ZONE_DMA32
287         /*
288          * x86_64 needs two ZONE_DMAs because it supports devices that are
289          * only able to do DMA to the lower 16M but also 32 bit devices that
290          * can only do DMA areas below 4G.
291          */
292         ZONE_DMA32,
293 #endif
294         /*
295          * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
296          * performed on pages in ZONE_NORMAL if the DMA devices support
297          * transfers to all addressable memory.
298          */
299         ZONE_NORMAL,
300 #ifdef CONFIG_HIGHMEM
301         /*
302          * A memory area that is only addressable by the kernel through
303          * mapping portions into its own address space. This is for example
304          * used by i386 to allow the kernel to address the memory beyond
305          * 900MB. The kernel will set up special mappings (page
306          * table entries on i386) for each page that the kernel needs to
307          * access.
308          */
309         ZONE_HIGHMEM,
310 #endif
311         ZONE_MOVABLE,
312         __MAX_NR_ZONES
313 };
314 
315 #ifndef __GENERATING_BOUNDS_H
316 
317 struct zone {
318         /* Fields commonly accessed by the page allocator */
319 
320         /* zone watermarks, access with *_wmark_pages(zone) macros */
321         unsigned long watermark[NR_WMARK];
322 
323         /*
324          * When free pages are below this point, additional steps are taken
325          * when reading the number of free pages to avoid per-cpu counter
326          * drift allowing watermarks to be breached
327          */
328         unsigned long percpu_drift_mark;
329 
330         /*
331          * We don't know if the memory that we're going to allocate will be freeable
332          * or/and it will be released eventually, so to avoid totally wasting several
333          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
334          * to run OOM on the lower zones despite there's tons of freeable ram
335          * on the higher zones). This array is recalculated at runtime if the
336          * sysctl_lowmem_reserve_ratio sysctl changes.
337          */
338         unsigned long           lowmem_reserve[MAX_NR_ZONES];
339 
340         /*
341          * This is a per-zone reserve of pages that should not be
342          * considered dirtyable memory.
343          */
344         unsigned long           dirty_balance_reserve;
345 
346 #ifdef CONFIG_NUMA
347         int node;
348         /*
349          * zone reclaim becomes active if more unmapped pages exist.
350          */
351         unsigned long           min_unmapped_pages;
352         unsigned long           min_slab_pages;
353 #endif
354         struct per_cpu_pageset __percpu *pageset;
355         /*
356          * free areas of different sizes
357          */
358         spinlock_t              lock;
359 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
360         /* Set to true when the PG_migrate_skip bits should be cleared */
361         bool                    compact_blockskip_flush;
362 
363         /* pfns where compaction scanners should start */
364         unsigned long           compact_cached_free_pfn;
365         unsigned long           compact_cached_migrate_pfn;
366 #endif
367 #ifdef CONFIG_MEMORY_HOTPLUG
368         /* see spanned/present_pages for more description */
369         seqlock_t               span_seqlock;
370 #endif
371         struct free_area        free_area[MAX_ORDER];
372 
373 #ifndef CONFIG_SPARSEMEM
374         /*
375          * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
376          * In SPARSEMEM, this map is stored in struct mem_section
377          */
378         unsigned long           *pageblock_flags;
379 #endif /* CONFIG_SPARSEMEM */
380 
381 #ifdef CONFIG_COMPACTION
382         /*
383          * On compaction failure, 1<<compact_defer_shift compactions
384          * are skipped before trying again. The number attempted since
385          * last failure is tracked with compact_considered.
386          */
387         unsigned int            compact_considered;
388         unsigned int            compact_defer_shift;
389         int                     compact_order_failed;
390 #endif
391 
392         ZONE_PADDING(_pad1_)
393 
394         /* Fields commonly accessed by the page reclaim scanner */
395         spinlock_t              lru_lock;
396         struct lruvec           lruvec;
397 
398         /* Evictions & activations on the inactive file list */
399         atomic_long_t           inactive_age;
400 
401         unsigned long           pages_scanned;     /* since last reclaim */
402         unsigned long           flags;             /* zone flags, see below */
403 
404         /* Zone statistics */
405         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
406 
407         /*
408          * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
409          * this zone's LRU.  Maintained by the pageout code.
410          */
411         unsigned int inactive_ratio;
412 
413 
414         ZONE_PADDING(_pad2_)
415         /* Rarely used or read-mostly fields */
416 
417         /*
418          * wait_table           -- the array holding the hash table
419          * wait_table_hash_nr_entries   -- the size of the hash table array
420          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
421          *
422          * The purpose of all these is to keep track of the people
423          * waiting for a page to become available and make them
424          * runnable again when possible. The trouble is that this
425          * consumes a lot of space, especially when so few things
426          * wait on pages at a given time. So instead of using
427          * per-page waitqueues, we use a waitqueue hash table.
428          *
429          * The bucket discipline is to sleep on the same queue when
430          * colliding and wake all in that wait queue when removing.
431          * When something wakes, it must check to be sure its page is
432          * truly available, a la thundering herd. The cost of a
433          * collision is great, but given the expected load of the
434          * table, they should be so rare as to be outweighed by the
435          * benefits from the saved space.
436          *
437          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
438          * primary users of these fields, and in mm/page_alloc.c
439          * free_area_init_core() performs the initialization of them.
440          */
441         wait_queue_head_t       * wait_table;
442         unsigned long           wait_table_hash_nr_entries;
443         unsigned long           wait_table_bits;
444 
445         /*
446          * Discontig memory support fields.
447          */
448         struct pglist_data      *zone_pgdat;
449         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
450         unsigned long           zone_start_pfn;
451 
452         /*
453          * spanned_pages is the total pages spanned by the zone, including
454          * holes, which is calculated as:
455          *      spanned_pages = zone_end_pfn - zone_start_pfn;
456          *
457          * present_pages is physical pages existing within the zone, which
458          * is calculated as:
459          *      present_pages = spanned_pages - absent_pages(pages in holes);
460          *
461          * managed_pages is present pages managed by the buddy system, which
462          * is calculated as (reserved_pages includes pages allocated by the
463          * bootmem allocator):
464          *      managed_pages = present_pages - reserved_pages;
465          *
466          * So present_pages may be used by memory hotplug or memory power
467          * management logic to figure out unmanaged pages by checking
468          * (present_pages - managed_pages). And managed_pages should be used
469          * by page allocator and vm scanner to calculate all kinds of watermarks
470          * and thresholds.
471          *
472          * Locking rules:
473          *
474          * zone_start_pfn and spanned_pages are protected by span_seqlock.
475          * It is a seqlock because it has to be read outside of zone->lock,
476          * and it is done in the main allocator path.  But, it is written
477          * quite infrequently.
478          *
479          * The span_seq lock is declared along with zone->lock because it is
480          * frequently read in proximity to zone->lock.  It's good to
481          * give them a chance of being in the same cacheline.
482          *
483          * Write access to present_pages at runtime should be protected by
484          * lock_memory_hotplug()/unlock_memory_hotplug().  Any reader who can't
485          * tolerant drift of present_pages should hold memory hotplug lock to
486          * get a stable value.
487          *
488          * Read access to managed_pages should be safe because it's unsigned
489          * long. Write access to zone->managed_pages and totalram_pages are
490          * protected by managed_page_count_lock at runtime. Idealy only
491          * adjust_managed_page_count() should be used instead of directly
492          * touching zone->managed_pages and totalram_pages.
493          */
494         unsigned long           spanned_pages;
495         unsigned long           present_pages;
496         unsigned long           managed_pages;
497 
498         /*
499          * Number of MIGRATE_RESEVE page block. To maintain for just
500          * optimization. Protected by zone->lock.
501          */
502         int                     nr_migrate_reserve_block;
503 
504         /*
505          * rarely used fields:
506          */
507         const char              *name;
508 } ____cacheline_internodealigned_in_smp;
509 
510 typedef enum {
511         ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
512         ZONE_OOM_LOCKED,                /* zone is in OOM killer zonelist */
513         ZONE_CONGESTED,                 /* zone has many dirty pages backed by
514                                          * a congested BDI
515                                          */
516         ZONE_TAIL_LRU_DIRTY,            /* reclaim scanning has recently found
517                                          * many dirty file pages at the tail
518                                          * of the LRU.
519                                          */
520         ZONE_WRITEBACK,                 /* reclaim scanning has recently found
521                                          * many pages under writeback
522                                          */
523 } zone_flags_t;
524 
525 static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
526 {
527         set_bit(flag, &zone->flags);
528 }
529 
530 static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
531 {
532         return test_and_set_bit(flag, &zone->flags);
533 }
534 
535 static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
536 {
537         clear_bit(flag, &zone->flags);
538 }
539 
540 static inline int zone_is_reclaim_congested(const struct zone *zone)
541 {
542         return test_bit(ZONE_CONGESTED, &zone->flags);
543 }
544 
545 static inline int zone_is_reclaim_dirty(const struct zone *zone)
546 {
547         return test_bit(ZONE_TAIL_LRU_DIRTY, &zone->flags);
548 }
549 
550 static inline int zone_is_reclaim_writeback(const struct zone *zone)
551 {
552         return test_bit(ZONE_WRITEBACK, &zone->flags);
553 }
554 
555 static inline int zone_is_reclaim_locked(const struct zone *zone)
556 {
557         return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
558 }
559 
560 static inline int zone_is_oom_locked(const struct zone *zone)
561 {
562         return test_bit(ZONE_OOM_LOCKED, &zone->flags);
563 }
564 
565 static inline unsigned long zone_end_pfn(const struct zone *zone)
566 {
567         return zone->zone_start_pfn + zone->spanned_pages;
568 }
569 
570 static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
571 {
572         return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
573 }
574 
575 static inline bool zone_is_initialized(struct zone *zone)
576 {
577         return !!zone->wait_table;
578 }
579 
580 static inline bool zone_is_empty(struct zone *zone)
581 {
582         return zone->spanned_pages == 0;
583 }
584 
585 /*
586  * The "priority" of VM scanning is how much of the queues we will scan in one
587  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
588  * queues ("queue_length >> 12") during an aging round.
589  */
590 #define DEF_PRIORITY 12
591 
592 /* Maximum number of zones on a zonelist */
593 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
594 
595 #ifdef CONFIG_NUMA
596 
597 /*
598  * The NUMA zonelists are doubled because we need zonelists that restrict the
599  * allocations to a single node for __GFP_THISNODE.
600  *
601  * [0]  : Zonelist with fallback
602  * [1]  : No fallback (__GFP_THISNODE)
603  */
604 #define MAX_ZONELISTS 2
605 
606 
607 /*
608  * We cache key information from each zonelist for smaller cache
609  * footprint when scanning for free pages in get_page_from_freelist().
610  *
611  * 1) The BITMAP fullzones tracks which zones in a zonelist have come
612  *    up short of free memory since the last time (last_fullzone_zap)
613  *    we zero'd fullzones.
614  * 2) The array z_to_n[] maps each zone in the zonelist to its node
615  *    id, so that we can efficiently evaluate whether that node is
616  *    set in the current tasks mems_allowed.
617  *
618  * Both fullzones and z_to_n[] are one-to-one with the zonelist,
619  * indexed by a zones offset in the zonelist zones[] array.
620  *
621  * The get_page_from_freelist() routine does two scans.  During the
622  * first scan, we skip zones whose corresponding bit in 'fullzones'
623  * is set or whose corresponding node in current->mems_allowed (which
624  * comes from cpusets) is not set.  During the second scan, we bypass
625  * this zonelist_cache, to ensure we look methodically at each zone.
626  *
627  * Once per second, we zero out (zap) fullzones, forcing us to
628  * reconsider nodes that might have regained more free memory.
629  * The field last_full_zap is the time we last zapped fullzones.
630  *
631  * This mechanism reduces the amount of time we waste repeatedly
632  * reexaming zones for free memory when they just came up low on
633  * memory momentarilly ago.
634  *
635  * The zonelist_cache struct members logically belong in struct
636  * zonelist.  However, the mempolicy zonelists constructed for
637  * MPOL_BIND are intentionally variable length (and usually much
638  * shorter).  A general purpose mechanism for handling structs with
639  * multiple variable length members is more mechanism than we want
640  * here.  We resort to some special case hackery instead.
641  *
642  * The MPOL_BIND zonelists don't need this zonelist_cache (in good
643  * part because they are shorter), so we put the fixed length stuff
644  * at the front of the zonelist struct, ending in a variable length
645  * zones[], as is needed by MPOL_BIND.
646  *
647  * Then we put the optional zonelist cache on the end of the zonelist
648  * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
649  * the fixed length portion at the front of the struct.  This pointer
650  * both enables us to find the zonelist cache, and in the case of
651  * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
652  * to know that the zonelist cache is not there.
653  *
654  * The end result is that struct zonelists come in two flavors:
655  *  1) The full, fixed length version, shown below, and
656  *  2) The custom zonelists for MPOL_BIND.
657  * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
658  *
659  * Even though there may be multiple CPU cores on a node modifying
660  * fullzones or last_full_zap in the same zonelist_cache at the same
661  * time, we don't lock it.  This is just hint data - if it is wrong now
662  * and then, the allocator will still function, perhaps a bit slower.
663  */
664 
665 
666 struct zonelist_cache {
667         unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];          /* zone->nid */
668         DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);      /* zone full? */
669         unsigned long last_full_zap;            /* when last zap'd (jiffies) */
670 };
671 #else
672 #define MAX_ZONELISTS 1
673 struct zonelist_cache;
674 #endif
675 
676 /*
677  * This struct contains information about a zone in a zonelist. It is stored
678  * here to avoid dereferences into large structures and lookups of tables
679  */
680 struct zoneref {
681         struct zone *zone;      /* Pointer to actual zone */
682         int zone_idx;           /* zone_idx(zoneref->zone) */
683 };
684 
685 /*
686  * One allocation request operates on a zonelist. A zonelist
687  * is a list of zones, the first one is the 'goal' of the
688  * allocation, the other zones are fallback zones, in decreasing
689  * priority.
690  *
691  * If zlcache_ptr is not NULL, then it is just the address of zlcache,
692  * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
693  * *
694  * To speed the reading of the zonelist, the zonerefs contain the zone index
695  * of the entry being read. Helper functions to access information given
696  * a struct zoneref are
697  *
698  * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
699  * zonelist_zone_idx()  - Return the index of the zone for an entry
700  * zonelist_node_idx()  - Return the index of the node for an entry
701  */
702 struct zonelist {
703         struct zonelist_cache *zlcache_ptr;                  // NULL or &zlcache
704         struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
705 #ifdef CONFIG_NUMA
706         struct zonelist_cache zlcache;                       // optional ...
707 #endif
708 };
709 
710 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
711 struct node_active_region {
712         unsigned long start_pfn;
713         unsigned long end_pfn;
714         int nid;
715 };
716 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
717 
718 #ifndef CONFIG_DISCONTIGMEM
719 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
720 extern struct page *mem_map;
721 #endif
722 
723 /*
724  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
725  * (mostly NUMA machines?) to denote a higher-level memory zone than the
726  * zone denotes.
727  *
728  * On NUMA machines, each NUMA node would have a pg_data_t to describe
729  * it's memory layout.
730  *
731  * Memory statistics and page replacement data structures are maintained on a
732  * per-zone basis.
733  */
734 struct bootmem_data;
735 typedef struct pglist_data {
736         struct zone node_zones[MAX_NR_ZONES];
737         struct zonelist node_zonelists[MAX_ZONELISTS];
738         int nr_zones;
739 #ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
740         struct page *node_mem_map;
741 #ifdef CONFIG_MEMCG
742         struct page_cgroup *node_page_cgroup;
743 #endif
744 #endif
745 #ifndef CONFIG_NO_BOOTMEM
746         struct bootmem_data *bdata;
747 #endif
748 #ifdef CONFIG_MEMORY_HOTPLUG
749         /*
750          * Must be held any time you expect node_start_pfn, node_present_pages
751          * or node_spanned_pages stay constant.  Holding this will also
752          * guarantee that any pfn_valid() stays that way.
753          *
754          * pgdat_resize_lock() and pgdat_resize_unlock() are provided to
755          * manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG.
756          *
757          * Nests above zone->lock and zone->span_seqlock
758          */
759         spinlock_t node_size_lock;
760 #endif
761         unsigned long node_start_pfn;
762         unsigned long node_present_pages; /* total number of physical pages */
763         unsigned long node_spanned_pages; /* total size of physical page
764                                              range, including holes */
765         int node_id;
766         nodemask_t reclaim_nodes;       /* Nodes allowed to reclaim from */
767         wait_queue_head_t kswapd_wait;
768         wait_queue_head_t pfmemalloc_wait;
769         struct task_struct *kswapd;     /* Protected by lock_memory_hotplug() */
770         int kswapd_max_order;
771         enum zone_type classzone_idx;
772 #ifdef CONFIG_NUMA_BALANCING
773         /* Lock serializing the migrate rate limiting window */
774         spinlock_t numabalancing_migrate_lock;
775 
776         /* Rate limiting time interval */
777         unsigned long numabalancing_migrate_next_window;
778 
779         /* Number of pages migrated during the rate limiting time interval */
780         unsigned long numabalancing_migrate_nr_pages;
781 #endif
782 } pg_data_t;
783 
784 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
785 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
786 #ifdef CONFIG_FLAT_NODE_MEM_MAP
787 #define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
788 #else
789 #define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
790 #endif
791 #define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
792 
793 #define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
794 #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
795 
796 static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
797 {
798         return pgdat->node_start_pfn + pgdat->node_spanned_pages;
799 }
800 
801 static inline bool pgdat_is_empty(pg_data_t *pgdat)
802 {
803         return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
804 }
805 
806 #include <linux/memory_hotplug.h>
807 
808 extern struct mutex zonelists_mutex;
809 void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
810 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
811 bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
812                 int classzone_idx, int alloc_flags);
813 bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
814                 int classzone_idx, int alloc_flags);
815 enum memmap_context {
816         MEMMAP_EARLY,
817         MEMMAP_HOTPLUG,
818 };
819 extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
820                                      unsigned long size,
821                                      enum memmap_context context);
822 
823 extern void lruvec_init(struct lruvec *lruvec);
824 
825 static inline struct zone *lruvec_zone(struct lruvec *lruvec)
826 {
827 #ifdef CONFIG_MEMCG
828         return lruvec->zone;
829 #else
830         return container_of(lruvec, struct zone, lruvec);
831 #endif
832 }
833 
834 #ifdef CONFIG_HAVE_MEMORY_PRESENT
835 void memory_present(int nid, unsigned long start, unsigned long end);
836 #else
837 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
838 #endif
839 
840 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
841 int local_memory_node(int node_id);
842 #else
843 static inline int local_memory_node(int node_id) { return node_id; };
844 #endif
845 
846 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
847 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
848 #endif
849 
850 /*
851  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
852  */
853 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
854 
855 static inline int populated_zone(struct zone *zone)
856 {
857         return (!!zone->present_pages);
858 }
859 
860 extern int movable_zone;
861 
862 static inline int zone_movable_is_highmem(void)
863 {
864 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
865         return movable_zone == ZONE_HIGHMEM;
866 #else
867         return 0;
868 #endif
869 }
870 
871 static inline int is_highmem_idx(enum zone_type idx)
872 {
873 #ifdef CONFIG_HIGHMEM
874         return (idx == ZONE_HIGHMEM ||
875                 (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
876 #else
877         return 0;
878 #endif
879 }
880 
881 /**
882  * is_highmem - helper function to quickly check if a struct zone is a 
883  *              highmem zone or not.  This is an attempt to keep references
884  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
885  * @zone - pointer to struct zone variable
886  */
887 static inline int is_highmem(struct zone *zone)
888 {
889 #ifdef CONFIG_HIGHMEM
890         int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
891         return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
892                (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
893                 zone_movable_is_highmem());
894 #else
895         return 0;
896 #endif
897 }
898 
899 /* These two functions are used to setup the per zone pages min values */
900 struct ctl_table;
901 int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
902                                         void __user *, size_t *, loff_t *);
903 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
904 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
905                                         void __user *, size_t *, loff_t *);
906 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
907                                         void __user *, size_t *, loff_t *);
908 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
909                         void __user *, size_t *, loff_t *);
910 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
911                         void __user *, size_t *, loff_t *);
912 
913 extern int numa_zonelist_order_handler(struct ctl_table *, int,
914                         void __user *, size_t *, loff_t *);
915 extern char numa_zonelist_order[];
916 #define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
917 
918 #ifndef CONFIG_NEED_MULTIPLE_NODES
919 
920 extern struct pglist_data contig_page_data;
921 #define NODE_DATA(nid)          (&contig_page_data)
922 #define NODE_MEM_MAP(nid)       mem_map
923 
924 #else /* CONFIG_NEED_MULTIPLE_NODES */
925 
926 #include <asm/mmzone.h>
927 
928 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
929 
930 extern struct pglist_data *first_online_pgdat(void);
931 extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
932 extern struct zone *next_zone(struct zone *zone);
933 
934 /**
935  * for_each_online_pgdat - helper macro to iterate over all online nodes
936  * @pgdat - pointer to a pg_data_t variable
937  */
938 #define for_each_online_pgdat(pgdat)                    \
939         for (pgdat = first_online_pgdat();              \
940              pgdat;                                     \
941              pgdat = next_online_pgdat(pgdat))
942 /**
943  * for_each_zone - helper macro to iterate over all memory zones
944  * @zone - pointer to struct zone variable
945  *
946  * The user only needs to declare the zone variable, for_each_zone
947  * fills it in.
948  */
949 #define for_each_zone(zone)                             \
950         for (zone = (first_online_pgdat())->node_zones; \
951              zone;                                      \
952              zone = next_zone(zone))
953 
954 #define for_each_populated_zone(zone)                   \
955         for (zone = (first_online_pgdat())->node_zones; \
956              zone;                                      \
957              zone = next_zone(zone))                    \
958                 if (!populated_zone(zone))              \
959                         ; /* do nothing */              \
960                 else
961 
962 static inline struct zone *zonelist_zone(struct zoneref *zoneref)
963 {
964         return zoneref->zone;
965 }
966 
967 static inline int zonelist_zone_idx(struct zoneref *zoneref)
968 {
969         return zoneref->zone_idx;
970 }
971 
972 static inline int zonelist_node_idx(struct zoneref *zoneref)
973 {
974 #ifdef CONFIG_NUMA
975         /* zone_to_nid not available in this context */
976         return zoneref->zone->node;
977 #else
978         return 0;
979 #endif /* CONFIG_NUMA */
980 }
981 
982 /**
983  * 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
984  * @z - The cursor used as a starting point for the search
985  * @highest_zoneidx - The zone index of the highest zone to return
986  * @nodes - An optional nodemask to filter the zonelist with
987  * @zone - The first suitable zone found is returned via this parameter
988  *
989  * This function returns the next zone at or below a given zone index that is
990  * within the allowed nodemask using a cursor as the starting point for the
991  * search. The zoneref returned is a cursor that represents the current zone
992  * being examined. It should be advanced by one before calling
993  * next_zones_zonelist again.
994  */
995 struct zoneref *next_zones_zonelist(struct zoneref *z,
996                                         enum zone_type highest_zoneidx,
997                                         nodemask_t *nodes,
998                                         struct zone **zone);
999 
1000 /**
1001  * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
1002  * @zonelist - The zonelist to search for a suitable zone
1003  * @highest_zoneidx - The zone index of the highest zone to return
1004  * @nodes - An optional nodemask to filter the zonelist with
1005  * @zone - The first suitable zone found is returned via this parameter
1006  *
1007  * This function returns the first zone at or below a given zone index that is
1008  * within the allowed nodemask. The zoneref returned is a cursor that can be
1009  * used to iterate the zonelist with next_zones_zonelist by advancing it by
1010  * one before calling.
1011  */
1012 static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
1013                                         enum zone_type highest_zoneidx,
1014                                         nodemask_t *nodes,
1015                                         struct zone **zone)
1016 {
1017         return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
1018                                                                 zone);
1019 }
1020 
1021 /**
1022  * 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
1023  * @zone - The current zone in the iterator
1024  * @z - The current pointer within zonelist->zones being iterated
1025  * @zlist - The zonelist being iterated
1026  * @highidx - The zone index of the highest zone to return
1027  * @nodemask - Nodemask allowed by the allocator
1028  *
1029  * This iterator iterates though all zones at or below a given zone index and
1030  * within a given nodemask
1031  */
1032 #define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
1033         for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
1034                 zone;                                                   \
1035                 z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
1036 
1037 /**
1038  * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
1039  * @zone - The current zone in the iterator
1040  * @z - The current pointer within zonelist->zones being iterated
1041  * @zlist - The zonelist being iterated
1042  * @highidx - The zone index of the highest zone to return
1043  *
1044  * This iterator iterates though all zones at or below a given zone index.
1045  */
1046 #define for_each_zone_zonelist(zone, z, zlist, highidx) \
1047         for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1048 
1049 #ifdef CONFIG_SPARSEMEM
1050 #include <asm/sparsemem.h>
1051 #endif
1052 
1053 #if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1054         !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1055 static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1056 {
1057         return 0;
1058 }
1059 #endif
1060 
1061 #ifdef CONFIG_FLATMEM
1062 #define pfn_to_nid(pfn)         (0)
1063 #endif
1064 
1065 #ifdef CONFIG_SPARSEMEM
1066 
1067 /*
1068  * SECTION_SHIFT                #bits space required to store a section #
1069  *
1070  * PA_SECTION_SHIFT             physical address to/from section number
1071  * PFN_SECTION_SHIFT            pfn to/from section number
1072  */
1073 #define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1074 #define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1075 
1076 #define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1077 
1078 #define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1079 #define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1080 
1081 #define SECTION_BLOCKFLAGS_BITS \
1082         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1083 
1084 #if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1085 #error Allocator MAX_ORDER exceeds SECTION_SIZE
1086 #endif
1087 
1088 #define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1089 #define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1090 
1091 #define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1092 #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1093 
1094 struct page;
1095 struct page_cgroup;
1096 struct mem_section {
1097         /*
1098          * This is, logically, a pointer to an array of struct
1099          * pages.  However, it is stored with some other magic.
1100          * (see sparse.c::sparse_init_one_section())
1101          *
1102          * Additionally during early boot we encode node id of
1103          * the location of the section here to guide allocation.
1104          * (see sparse.c::memory_present())
1105          *
1106          * Making it a UL at least makes someone do a cast
1107          * before using it wrong.
1108          */
1109         unsigned long section_mem_map;
1110 
1111         /* See declaration of similar field in struct zone */
1112         unsigned long *pageblock_flags;
1113 #ifdef CONFIG_MEMCG
1114         /*
1115          * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1116          * section. (see memcontrol.h/page_cgroup.h about this.)
1117          */
1118         struct page_cgroup *page_cgroup;
1119         unsigned long pad;
1120 #endif
1121         /*
1122          * WARNING: mem_section must be a power-of-2 in size for the
1123          * calculation and use of SECTION_ROOT_MASK to make sense.
1124          */
1125 };
1126 
1127 #ifdef CONFIG_SPARSEMEM_EXTREME
1128 #define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1129 #else
1130 #define SECTIONS_PER_ROOT       1
1131 #endif
1132 
1133 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1134 #define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1135 #define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1136 
1137 #ifdef CONFIG_SPARSEMEM_EXTREME
1138 extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1139 #else
1140 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1141 #endif
1142 
1143 static inline struct mem_section *__nr_to_section(unsigned long nr)
1144 {
1145         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1146                 return NULL;
1147         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1148 }
1149 extern int __section_nr(struct mem_section* ms);
1150 extern unsigned long usemap_size(void);
1151 
1152 /*
1153  * We use the lower bits of the mem_map pointer to store
1154  * a little bit of information.  There should be at least
1155  * 3 bits here due to 32-bit alignment.
1156  */
1157 #define SECTION_MARKED_PRESENT  (1UL<<0)
1158 #define SECTION_HAS_MEM_MAP     (1UL<<1)
1159 #define SECTION_MAP_LAST_BIT    (1UL<<2)
1160 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1161 #define SECTION_NID_SHIFT       2
1162 
1163 static inline struct page *__section_mem_map_addr(struct mem_section *section)
1164 {
1165         unsigned long map = section->section_mem_map;
1166         map &= SECTION_MAP_MASK;
1167         return (struct page *)map;
1168 }
1169 
1170 static inline int present_section(struct mem_section *section)
1171 {
1172         return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1173 }
1174 
1175 static inline int present_section_nr(unsigned long nr)
1176 {
1177         return present_section(__nr_to_section(nr));
1178 }
1179 
1180 static inline int valid_section(struct mem_section *section)
1181 {
1182         return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1183 }
1184 
1185 static inline int valid_section_nr(unsigned long nr)
1186 {
1187         return valid_section(__nr_to_section(nr));
1188 }
1189 
1190 static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1191 {
1192         return __nr_to_section(pfn_to_section_nr(pfn));
1193 }
1194 
1195 #ifndef CONFIG_HAVE_ARCH_PFN_VALID
1196 static inline int pfn_valid(unsigned long pfn)
1197 {
1198         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1199                 return 0;
1200         return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1201 }
1202 #endif
1203 
1204 static inline int pfn_present(unsigned long pfn)
1205 {
1206         if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1207                 return 0;
1208         return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1209 }
1210 
1211 /*
1212  * These are _only_ used during initialisation, therefore they
1213  * can use __initdata ...  They could have names to indicate
1214  * this restriction.
1215  */
1216 #ifdef CONFIG_NUMA
1217 #define pfn_to_nid(pfn)                                                 \
1218 ({                                                                      \
1219         unsigned long __pfn_to_nid_pfn = (pfn);                         \
1220         page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1221 })
1222 #else
1223 #define pfn_to_nid(pfn)         (0)
1224 #endif
1225 
1226 #define early_pfn_valid(pfn)    pfn_valid(pfn)
1227 void sparse_init(void);
1228 #else
1229 #define sparse_init()   do {} while (0)
1230 #define sparse_index_init(_sec, _nid)  do {} while (0)
1231 #endif /* CONFIG_SPARSEMEM */
1232 
1233 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
1234 bool early_pfn_in_nid(unsigned long pfn, int nid);
1235 #else
1236 #define early_pfn_in_nid(pfn, nid)      (1)
1237 #endif
1238 
1239 #ifndef early_pfn_valid
1240 #define early_pfn_valid(pfn)    (1)
1241 #endif
1242 
1243 void memory_present(int nid, unsigned long start, unsigned long end);
1244 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1245 
1246 /*
1247  * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1248  * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1249  * pfn_valid_within() should be used in this case; we optimise this away
1250  * when we have no holes within a MAX_ORDER_NR_PAGES block.
1251  */
1252 #ifdef CONFIG_HOLES_IN_ZONE
1253 #define pfn_valid_within(pfn) pfn_valid(pfn)
1254 #else
1255 #define pfn_valid_within(pfn) (1)
1256 #endif
1257 
1258 #ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1259 /*
1260  * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1261  * associated with it or not. In FLATMEM, it is expected that holes always
1262  * have valid memmap as long as there is valid PFNs either side of the hole.
1263  * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1264  * entire section.
1265  *
1266  * However, an ARM, and maybe other embedded architectures in the future
1267  * free memmap backing holes to save memory on the assumption the memmap is
1268  * never used. The page_zone linkages are then broken even though pfn_valid()
1269  * returns true. A walker of the full memmap must then do this additional
1270  * check to ensure the memmap they are looking at is sane by making sure
1271  * the zone and PFN linkages are still valid. This is expensive, but walkers
1272  * of the full memmap are extremely rare.
1273  */
1274 int memmap_valid_within(unsigned long pfn,
1275                                         struct page *page, struct zone *zone);
1276 #else
1277 static inline int memmap_valid_within(unsigned long pfn,
1278                                         struct page *page, struct zone *zone)
1279 {
1280         return 1;
1281 }
1282 #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1283 
1284 #endif /* !__GENERATING_BOUNDS.H */
1285 #endif /* !__ASSEMBLY__ */
1286 #endif /* _LINUX_MMZONE_H */
1287 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us