linux/include/linux/mmzone.h
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   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 <generated/bounds.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
  38enum {
  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        MIGRATE_ISOLATE,        /* can't allocate from here */
  61        MIGRATE_TYPES
  62};
  63
  64#ifdef CONFIG_CMA
  65#  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
  66#  define cma_wmark_pages(zone) zone->min_cma_pages
  67#else
  68#  define is_migrate_cma(migratetype) false
  69#  define cma_wmark_pages(zone) 0
  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
  76extern int page_group_by_mobility_disabled;
  77
  78static inline int get_pageblock_migratetype(struct page *page)
  79{
  80        return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
  81}
  82
  83struct free_area {
  84        struct list_head        free_list[MIGRATE_TYPES];
  85        unsigned long           nr_free;
  86};
  87
  88struct 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)
  97struct 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
 105enum zone_stat_item {
 106        /* First 128 byte cacheline (assuming 64 bit words) */
 107        NR_FREE_PAGES,
 108        NR_LRU_BASE,
 109        NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
 110        NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
 111        NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
 112        NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
 113        NR_UNEVICTABLE,         /*  "     "     "   "       "         */
 114        NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
 115        NR_ANON_PAGES,  /* Mapped anonymous pages */
 116        NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
 117                           only modified from process context */
 118        NR_FILE_PAGES,
 119        NR_FILE_DIRTY,
 120        NR_WRITEBACK,
 121        NR_SLAB_RECLAIMABLE,
 122        NR_SLAB_UNRECLAIMABLE,
 123        NR_PAGETABLE,           /* used for pagetables */
 124        NR_KERNEL_STACK,
 125        /* Second 128 byte cacheline */
 126        NR_UNSTABLE_NFS,        /* NFS unstable pages */
 127        NR_BOUNCE,
 128        NR_VMSCAN_WRITE,
 129        NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
 130        NR_WRITEBACK_TEMP,      /* Writeback using temporary buffers */
 131        NR_ISOLATED_ANON,       /* Temporary isolated pages from anon lru */
 132        NR_ISOLATED_FILE,       /* Temporary isolated pages from file lru */
 133        NR_SHMEM,               /* shmem pages (included tmpfs/GEM pages) */
 134        NR_DIRTIED,             /* page dirtyings since bootup */
 135        NR_WRITTEN,             /* page writings since bootup */
 136#ifdef CONFIG_NUMA
 137        NUMA_HIT,               /* allocated in intended node */
 138        NUMA_MISS,              /* allocated in non intended node */
 139        NUMA_FOREIGN,           /* was intended here, hit elsewhere */
 140        NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
 141        NUMA_LOCAL,             /* allocation from local node */
 142        NUMA_OTHER,             /* allocation from other node */
 143#endif
 144        NR_ANON_TRANSPARENT_HUGEPAGES,
 145        NR_FREE_CMA_PAGES,
 146        NR_VM_ZONE_STAT_ITEMS };
 147
 148/*
 149 * We do arithmetic on the LRU lists in various places in the code,
 150 * so it is important to keep the active lists LRU_ACTIVE higher in
 151 * the array than the corresponding inactive lists, and to keep
 152 * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
 153 *
 154 * This has to be kept in sync with the statistics in zone_stat_item
 155 * above and the descriptions in vmstat_text in mm/vmstat.c
 156 */
 157#define LRU_BASE 0
 158#define LRU_ACTIVE 1
 159#define LRU_FILE 2
 160
 161enum lru_list {
 162        LRU_INACTIVE_ANON = LRU_BASE,
 163        LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
 164        LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
 165        LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
 166        LRU_UNEVICTABLE,
 167        NR_LRU_LISTS
 168};
 169
 170#define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)
 171
 172#define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)
 173
 174static inline int is_file_lru(enum lru_list lru)
 175{
 176        return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
 177}
 178
 179static inline int is_active_lru(enum lru_list lru)
 180{
 181        return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
 182}
 183
 184static inline int is_unevictable_lru(enum lru_list lru)
 185{
 186        return (lru == LRU_UNEVICTABLE);
 187}
 188
 189struct zone_reclaim_stat {
 190        /*
 191         * The pageout code in vmscan.c keeps track of how many of the
 192         * mem/swap backed and file backed pages are referenced.
 193         * The higher the rotated/scanned ratio, the more valuable
 194         * that cache is.
 195         *
 196         * The anon LRU stats live in [0], file LRU stats in [1]
 197         */
 198        unsigned long           recent_rotated[2];
 199        unsigned long           recent_scanned[2];
 200};
 201
 202struct lruvec {
 203        struct list_head lists[NR_LRU_LISTS];
 204        struct zone_reclaim_stat reclaim_stat;
 205#ifdef CONFIG_MEMCG
 206        struct zone *zone;
 207#endif
 208};
 209
 210/* Mask used at gathering information at once (see memcontrol.c) */
 211#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
 212#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
 213#define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)
 214
 215/* Isolate clean file */
 216#define ISOLATE_CLEAN           ((__force isolate_mode_t)0x1)
 217/* Isolate unmapped file */
 218#define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x2)
 219/* Isolate for asynchronous migration */
 220#define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
 221/* Isolate unevictable pages */
 222#define ISOLATE_UNEVICTABLE     ((__force isolate_mode_t)0x8)
 223
 224/* LRU Isolation modes. */
 225typedef unsigned __bitwise__ isolate_mode_t;
 226
 227enum zone_watermarks {
 228        WMARK_MIN,
 229        WMARK_LOW,
 230        WMARK_HIGH,
 231        NR_WMARK
 232};
 233
 234#define min_wmark_pages(z) (z->watermark[WMARK_MIN])
 235#define low_wmark_pages(z) (z->watermark[WMARK_LOW])
 236#define high_wmark_pages(z) (z->watermark[WMARK_HIGH])
 237
 238struct per_cpu_pages {
 239        int count;              /* number of pages in the list */
 240        int high;               /* high watermark, emptying needed */
 241        int batch;              /* chunk size for buddy add/remove */
 242
 243        /* Lists of pages, one per migrate type stored on the pcp-lists */
 244        struct list_head lists[MIGRATE_PCPTYPES];
 245};
 246
 247struct per_cpu_pageset {
 248        struct per_cpu_pages pcp;
 249#ifdef CONFIG_NUMA
 250        s8 expire;
 251#endif
 252#ifdef CONFIG_SMP
 253        s8 stat_threshold;
 254        s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
 255#endif
 256};
 257
 258#endif /* !__GENERATING_BOUNDS.H */
 259
 260enum zone_type {
 261#ifdef CONFIG_ZONE_DMA
 262        /*
 263         * ZONE_DMA is used when there are devices that are not able
 264         * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
 265         * carve out the portion of memory that is needed for these devices.
 266         * The range is arch specific.
 267         *
 268         * Some examples
 269         *
 270         * Architecture         Limit
 271         * ---------------------------
 272         * parisc, ia64, sparc  <4G
 273         * s390                 <2G
 274         * arm                  Various
 275         * alpha                Unlimited or 0-16MB.
 276         *
 277         * i386, x86_64 and multiple other arches
 278         *                      <16M.
 279         */
 280        ZONE_DMA,
 281#endif
 282#ifdef CONFIG_ZONE_DMA32
 283        /*
 284         * x86_64 needs two ZONE_DMAs because it supports devices that are
 285         * only able to do DMA to the lower 16M but also 32 bit devices that
 286         * can only do DMA areas below 4G.
 287         */
 288        ZONE_DMA32,
 289#endif
 290        /*
 291         * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
 292         * performed on pages in ZONE_NORMAL if the DMA devices support
 293         * transfers to all addressable memory.
 294         */
 295        ZONE_NORMAL,
 296#ifdef CONFIG_HIGHMEM
 297        /*
 298         * A memory area that is only addressable by the kernel through
 299         * mapping portions into its own address space. This is for example
 300         * used by i386 to allow the kernel to address the memory beyond
 301         * 900MB. The kernel will set up special mappings (page
 302         * table entries on i386) for each page that the kernel needs to
 303         * access.
 304         */
 305        ZONE_HIGHMEM,
 306#endif
 307        ZONE_MOVABLE,
 308        __MAX_NR_ZONES
 309};
 310
 311#ifndef __GENERATING_BOUNDS_H
 312
 313/*
 314 * When a memory allocation must conform to specific limitations (such
 315 * as being suitable for DMA) the caller will pass in hints to the
 316 * allocator in the gfp_mask, in the zone modifier bits.  These bits
 317 * are used to select a priority ordered list of memory zones which
 318 * match the requested limits. See gfp_zone() in include/linux/gfp.h
 319 */
 320
 321#if MAX_NR_ZONES < 2
 322#define ZONES_SHIFT 0
 323#elif MAX_NR_ZONES <= 2
 324#define ZONES_SHIFT 1
 325#elif MAX_NR_ZONES <= 4
 326#define ZONES_SHIFT 2
 327#else
 328#error ZONES_SHIFT -- too many zones configured adjust calculation
 329#endif
 330
 331struct zone {
 332        /* Fields commonly accessed by the page allocator */
 333
 334        /* zone watermarks, access with *_wmark_pages(zone) macros */
 335        unsigned long watermark[NR_WMARK];
 336
 337        /*
 338         * When free pages are below this point, additional steps are taken
 339         * when reading the number of free pages to avoid per-cpu counter
 340         * drift allowing watermarks to be breached
 341         */
 342        unsigned long percpu_drift_mark;
 343
 344        /*
 345         * We don't know if the memory that we're going to allocate will be freeable
 346         * or/and it will be released eventually, so to avoid totally wasting several
 347         * GB of ram we must reserve some of the lower zone memory (otherwise we risk
 348         * to run OOM on the lower zones despite there's tons of freeable ram
 349         * on the higher zones). This array is recalculated at runtime if the
 350         * sysctl_lowmem_reserve_ratio sysctl changes.
 351         */
 352        unsigned long           lowmem_reserve[MAX_NR_ZONES];
 353
 354        /*
 355         * This is a per-zone reserve of pages that should not be
 356         * considered dirtyable memory.
 357         */
 358        unsigned long           dirty_balance_reserve;
 359
 360#ifdef CONFIG_NUMA
 361        int node;
 362        /*
 363         * zone reclaim becomes active if more unmapped pages exist.
 364         */
 365        unsigned long           min_unmapped_pages;
 366        unsigned long           min_slab_pages;
 367#endif
 368        struct per_cpu_pageset __percpu *pageset;
 369        /*
 370         * free areas of different sizes
 371         */
 372        spinlock_t              lock;
 373        int                     all_unreclaimable; /* All pages pinned */
 374#if defined CONFIG_COMPACTION || defined CONFIG_CMA
 375        /* Set to true when the PG_migrate_skip bits should be cleared */
 376        bool                    compact_blockskip_flush;
 377
 378        /* pfns where compaction scanners should start */
 379        unsigned long           compact_cached_free_pfn;
 380        unsigned long           compact_cached_migrate_pfn;
 381#endif
 382#ifdef CONFIG_MEMORY_HOTPLUG
 383        /* see spanned/present_pages for more description */
 384        seqlock_t               span_seqlock;
 385#endif
 386#ifdef CONFIG_CMA
 387        /*
 388         * CMA needs to increase watermark levels during the allocation
 389         * process to make sure that the system is not starved.
 390         */
 391        unsigned long           min_cma_pages;
 392#endif
 393        struct free_area        free_area[MAX_ORDER];
 394
 395#ifndef CONFIG_SPARSEMEM
 396        /*
 397         * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
 398         * In SPARSEMEM, this map is stored in struct mem_section
 399         */
 400        unsigned long           *pageblock_flags;
 401#endif /* CONFIG_SPARSEMEM */
 402
 403#ifdef CONFIG_COMPACTION
 404        /*
 405         * On compaction failure, 1<<compact_defer_shift compactions
 406         * are skipped before trying again. The number attempted since
 407         * last failure is tracked with compact_considered.
 408         */
 409        unsigned int            compact_considered;
 410        unsigned int            compact_defer_shift;
 411        int                     compact_order_failed;
 412#endif
 413
 414        ZONE_PADDING(_pad1_)
 415
 416        /* Fields commonly accessed by the page reclaim scanner */
 417        spinlock_t              lru_lock;
 418        struct lruvec           lruvec;
 419
 420        unsigned long           pages_scanned;     /* since last reclaim */
 421        unsigned long           flags;             /* zone flags, see below */
 422
 423        /* Zone statistics */
 424        atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
 425
 426        /*
 427         * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
 428         * this zone's LRU.  Maintained by the pageout code.
 429         */
 430        unsigned int inactive_ratio;
 431
 432
 433        ZONE_PADDING(_pad2_)
 434        /* Rarely used or read-mostly fields */
 435
 436        /*
 437         * wait_table           -- the array holding the hash table
 438         * wait_table_hash_nr_entries   -- the size of the hash table array
 439         * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
 440         *
 441         * The purpose of all these is to keep track of the people
 442         * waiting for a page to become available and make them
 443         * runnable again when possible. The trouble is that this
 444         * consumes a lot of space, especially when so few things
 445         * wait on pages at a given time. So instead of using
 446         * per-page waitqueues, we use a waitqueue hash table.
 447         *
 448         * The bucket discipline is to sleep on the same queue when
 449         * colliding and wake all in that wait queue when removing.
 450         * When something wakes, it must check to be sure its page is
 451         * truly available, a la thundering herd. The cost of a
 452         * collision is great, but given the expected load of the
 453         * table, they should be so rare as to be outweighed by the
 454         * benefits from the saved space.
 455         *
 456         * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
 457         * primary users of these fields, and in mm/page_alloc.c
 458         * free_area_init_core() performs the initialization of them.
 459         */
 460        wait_queue_head_t       * wait_table;
 461        unsigned long           wait_table_hash_nr_entries;
 462        unsigned long           wait_table_bits;
 463
 464        /*
 465         * Discontig memory support fields.
 466         */
 467        struct pglist_data      *zone_pgdat;
 468        /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
 469        unsigned long           zone_start_pfn;
 470
 471        /*
 472         * zone_start_pfn, spanned_pages and present_pages are all
 473         * protected by span_seqlock.  It is a seqlock because it has
 474         * to be read outside of zone->lock, and it is done in the main
 475         * allocator path.  But, it is written quite infrequently.
 476         *
 477         * The lock is declared along with zone->lock because it is
 478         * frequently read in proximity to zone->lock.  It's good to
 479         * give them a chance of being in the same cacheline.
 480         */
 481        unsigned long           spanned_pages;  /* total size, including holes */
 482        unsigned long           present_pages;  /* amount of memory (excluding holes) */
 483
 484        /*
 485         * rarely used fields:
 486         */
 487        const char              *name;
 488#ifdef CONFIG_MEMORY_ISOLATION
 489        /*
 490         * the number of MIGRATE_ISOLATE *pageblock*.
 491         * We need this for free page counting. Look at zone_watermark_ok_safe.
 492         * It's protected by zone->lock
 493         */
 494        int             nr_pageblock_isolate;
 495#endif
 496} ____cacheline_internodealigned_in_smp;
 497
 498typedef enum {
 499        ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
 500        ZONE_OOM_LOCKED,                /* zone is in OOM killer zonelist */
 501        ZONE_CONGESTED,                 /* zone has many dirty pages backed by
 502                                         * a congested BDI
 503                                         */
 504} zone_flags_t;
 505
 506static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
 507{
 508        set_bit(flag, &zone->flags);
 509}
 510
 511static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
 512{
 513        return test_and_set_bit(flag, &zone->flags);
 514}
 515
 516static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
 517{
 518        clear_bit(flag, &zone->flags);
 519}
 520
 521static inline int zone_is_reclaim_congested(const struct zone *zone)
 522{
 523        return test_bit(ZONE_CONGESTED, &zone->flags);
 524}
 525
 526static inline int zone_is_reclaim_locked(const struct zone *zone)
 527{
 528        return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
 529}
 530
 531static inline int zone_is_oom_locked(const struct zone *zone)
 532{
 533        return test_bit(ZONE_OOM_LOCKED, &zone->flags);
 534}
 535
 536/*
 537 * The "priority" of VM scanning is how much of the queues we will scan in one
 538 * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
 539 * queues ("queue_length >> 12") during an aging round.
 540 */
 541#define DEF_PRIORITY 12
 542
 543/* Maximum number of zones on a zonelist */
 544#define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
 545
 546#ifdef CONFIG_NUMA
 547
 548/*
 549 * The NUMA zonelists are doubled because we need zonelists that restrict the
 550 * allocations to a single node for GFP_THISNODE.
 551 *
 552 * [0]  : Zonelist with fallback
 553 * [1]  : No fallback (GFP_THISNODE)
 554 */
 555#define MAX_ZONELISTS 2
 556
 557
 558/*
 559 * We cache key information from each zonelist for smaller cache
 560 * footprint when scanning for free pages in get_page_from_freelist().
 561 *
 562 * 1) The BITMAP fullzones tracks which zones in a zonelist have come
 563 *    up short of free memory since the last time (last_fullzone_zap)
 564 *    we zero'd fullzones.
 565 * 2) The array z_to_n[] maps each zone in the zonelist to its node
 566 *    id, so that we can efficiently evaluate whether that node is
 567 *    set in the current tasks mems_allowed.
 568 *
 569 * Both fullzones and z_to_n[] are one-to-one with the zonelist,
 570 * indexed by a zones offset in the zonelist zones[] array.
 571 *
 572 * The get_page_from_freelist() routine does two scans.  During the
 573 * first scan, we skip zones whose corresponding bit in 'fullzones'
 574 * is set or whose corresponding node in current->mems_allowed (which
 575 * comes from cpusets) is not set.  During the second scan, we bypass
 576 * this zonelist_cache, to ensure we look methodically at each zone.
 577 *
 578 * Once per second, we zero out (zap) fullzones, forcing us to
 579 * reconsider nodes that might have regained more free memory.
 580 * The field last_full_zap is the time we last zapped fullzones.
 581 *
 582 * This mechanism reduces the amount of time we waste repeatedly
 583 * reexaming zones for free memory when they just came up low on
 584 * memory momentarilly ago.
 585 *
 586 * The zonelist_cache struct members logically belong in struct
 587 * zonelist.  However, the mempolicy zonelists constructed for
 588 * MPOL_BIND are intentionally variable length (and usually much
 589 * shorter).  A general purpose mechanism for handling structs with
 590 * multiple variable length members is more mechanism than we want
 591 * here.  We resort to some special case hackery instead.
 592 *
 593 * The MPOL_BIND zonelists don't need this zonelist_cache (in good
 594 * part because they are shorter), so we put the fixed length stuff
 595 * at the front of the zonelist struct, ending in a variable length
 596 * zones[], as is needed by MPOL_BIND.
 597 *
 598 * Then we put the optional zonelist cache on the end of the zonelist
 599 * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
 600 * the fixed length portion at the front of the struct.  This pointer
 601 * both enables us to find the zonelist cache, and in the case of
 602 * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
 603 * to know that the zonelist cache is not there.
 604 *
 605 * The end result is that struct zonelists come in two flavors:
 606 *  1) The full, fixed length version, shown below, and
 607 *  2) The custom zonelists for MPOL_BIND.
 608 * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
 609 *
 610 * Even though there may be multiple CPU cores on a node modifying
 611 * fullzones or last_full_zap in the same zonelist_cache at the same
 612 * time, we don't lock it.  This is just hint data - if it is wrong now
 613 * and then, the allocator will still function, perhaps a bit slower.
 614 */
 615
 616
 617struct zonelist_cache {
 618        unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];          /* zone->nid */
 619        DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);      /* zone full? */
 620        unsigned long last_full_zap;            /* when last zap'd (jiffies) */
 621};
 622#else
 623#define MAX_ZONELISTS 1
 624struct zonelist_cache;
 625#endif
 626
 627/*
 628 * This struct contains information about a zone in a zonelist. It is stored
 629 * here to avoid dereferences into large structures and lookups of tables
 630 */
 631struct zoneref {
 632        struct zone *zone;      /* Pointer to actual zone */
 633        int zone_idx;           /* zone_idx(zoneref->zone) */
 634};
 635
 636/*
 637 * One allocation request operates on a zonelist. A zonelist
 638 * is a list of zones, the first one is the 'goal' of the
 639 * allocation, the other zones are fallback zones, in decreasing
 640 * priority.
 641 *
 642 * If zlcache_ptr is not NULL, then it is just the address of zlcache,
 643 * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
 644 * *
 645 * To speed the reading of the zonelist, the zonerefs contain the zone index
 646 * of the entry being read. Helper functions to access information given
 647 * a struct zoneref are
 648 *
 649 * zonelist_zone()      - Return the struct zone * for an entry in _zonerefs
 650 * zonelist_zone_idx()  - Return the index of the zone for an entry
 651 * zonelist_node_idx()  - Return the index of the node for an entry
 652 */
 653struct zonelist {
 654        struct zonelist_cache *zlcache_ptr;                  // NULL or &zlcache
 655        struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
 656#ifdef CONFIG_NUMA
 657        struct zonelist_cache zlcache;                       // optional ...
 658#endif
 659};
 660
 661#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 662struct node_active_region {
 663        unsigned long start_pfn;
 664        unsigned long end_pfn;
 665        int nid;
 666};
 667#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 668
 669#ifndef CONFIG_DISCONTIGMEM
 670/* The array of struct pages - for discontigmem use pgdat->lmem_map */
 671extern struct page *mem_map;
 672#endif
 673
 674/*
 675 * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
 676 * (mostly NUMA machines?) to denote a higher-level memory zone than the
 677 * zone denotes.
 678 *
 679 * On NUMA machines, each NUMA node would have a pg_data_t to describe
 680 * it's memory layout.
 681 *
 682 * Memory statistics and page replacement data structures are maintained on a
 683 * per-zone basis.
 684 */
 685struct bootmem_data;
 686typedef struct pglist_data {
 687        struct zone node_zones[MAX_NR_ZONES];
 688        struct zonelist node_zonelists[MAX_ZONELISTS];
 689        int nr_zones;
 690#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
 691        struct page *node_mem_map;
 692#ifdef CONFIG_MEMCG
 693        struct page_cgroup *node_page_cgroup;
 694#endif
 695#endif
 696#ifndef CONFIG_NO_BOOTMEM
 697        struct bootmem_data *bdata;
 698#endif
 699#ifdef CONFIG_MEMORY_HOTPLUG
 700        /*
 701         * Must be held any time you expect node_start_pfn, node_present_pages
 702         * or node_spanned_pages stay constant.  Holding this will also
 703         * guarantee that any pfn_valid() stays that way.
 704         *
 705         * Nests above zone->lock and zone->size_seqlock.
 706         */
 707        spinlock_t node_size_lock;
 708#endif
 709        unsigned long node_start_pfn;
 710        unsigned long node_present_pages; /* total number of physical pages */
 711        unsigned long node_spanned_pages; /* total size of physical page
 712                                             range, including holes */
 713        int node_id;
 714        nodemask_t reclaim_nodes;       /* Nodes allowed to reclaim from */
 715        wait_queue_head_t kswapd_wait;
 716        wait_queue_head_t pfmemalloc_wait;
 717        struct task_struct *kswapd;     /* Protected by lock_memory_hotplug() */
 718        int kswapd_max_order;
 719        enum zone_type classzone_idx;
 720} pg_data_t;
 721
 722#define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
 723#define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
 724#ifdef CONFIG_FLAT_NODE_MEM_MAP
 725#define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
 726#else
 727#define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
 728#endif
 729#define nid_page_nr(nid, pagenr)        pgdat_page_nr(NODE_DATA(nid),(pagenr))
 730
 731#define node_start_pfn(nid)     (NODE_DATA(nid)->node_start_pfn)
 732
 733#define node_end_pfn(nid) ({\
 734        pg_data_t *__pgdat = NODE_DATA(nid);\
 735        __pgdat->node_start_pfn + __pgdat->node_spanned_pages;\
 736})
 737
 738#include <linux/memory_hotplug.h>
 739
 740extern struct mutex zonelists_mutex;
 741void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
 742void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
 743bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 744                int classzone_idx, int alloc_flags);
 745bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
 746                int classzone_idx, int alloc_flags);
 747enum memmap_context {
 748        MEMMAP_EARLY,
 749        MEMMAP_HOTPLUG,
 750};
 751extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
 752                                     unsigned long size,
 753                                     enum memmap_context context);
 754
 755extern void lruvec_init(struct lruvec *lruvec);
 756
 757static inline struct zone *lruvec_zone(struct lruvec *lruvec)
 758{
 759#ifdef CONFIG_MEMCG
 760        return lruvec->zone;
 761#else
 762        return container_of(lruvec, struct zone, lruvec);
 763#endif
 764}
 765
 766#ifdef CONFIG_HAVE_MEMORY_PRESENT
 767void memory_present(int nid, unsigned long start, unsigned long end);
 768#else
 769static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
 770#endif
 771
 772#ifdef CONFIG_HAVE_MEMORYLESS_NODES
 773int local_memory_node(int node_id);
 774#else
 775static inline int local_memory_node(int node_id) { return node_id; };
 776#endif
 777
 778#ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
 779unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 780#endif
 781
 782/*
 783 * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
 784 */
 785#define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
 786
 787static inline int populated_zone(struct zone *zone)
 788{
 789        return (!!zone->present_pages);
 790}
 791
 792extern int movable_zone;
 793
 794static inline int zone_movable_is_highmem(void)
 795{
 796#if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
 797        return movable_zone == ZONE_HIGHMEM;
 798#else
 799        return 0;
 800#endif
 801}
 802
 803static inline int is_highmem_idx(enum zone_type idx)
 804{
 805#ifdef CONFIG_HIGHMEM
 806        return (idx == ZONE_HIGHMEM ||
 807                (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
 808#else
 809        return 0;
 810#endif
 811}
 812
 813static inline int is_normal_idx(enum zone_type idx)
 814{
 815        return (idx == ZONE_NORMAL);
 816}
 817
 818/**
 819 * is_highmem - helper function to quickly check if a struct zone is a 
 820 *              highmem zone or not.  This is an attempt to keep references
 821 *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
 822 * @zone - pointer to struct zone variable
 823 */
 824static inline int is_highmem(struct zone *zone)
 825{
 826#ifdef CONFIG_HIGHMEM
 827        int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
 828        return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
 829               (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
 830                zone_movable_is_highmem());
 831#else
 832        return 0;
 833#endif
 834}
 835
 836static inline int is_normal(struct zone *zone)
 837{
 838        return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
 839}
 840
 841static inline int is_dma32(struct zone *zone)
 842{
 843#ifdef CONFIG_ZONE_DMA32
 844        return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
 845#else
 846        return 0;
 847#endif
 848}
 849
 850static inline int is_dma(struct zone *zone)
 851{
 852#ifdef CONFIG_ZONE_DMA
 853        return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
 854#else
 855        return 0;
 856#endif
 857}
 858
 859/* These two functions are used to setup the per zone pages min values */
 860struct ctl_table;
 861int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
 862                                        void __user *, size_t *, loff_t *);
 863extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 864int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
 865                                        void __user *, size_t *, loff_t *);
 866int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
 867                                        void __user *, size_t *, loff_t *);
 868int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
 869                        void __user *, size_t *, loff_t *);
 870int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
 871                        void __user *, size_t *, loff_t *);
 872
 873extern int numa_zonelist_order_handler(struct ctl_table *, int,
 874                        void __user *, size_t *, loff_t *);
 875extern char numa_zonelist_order[];
 876#define NUMA_ZONELIST_ORDER_LEN 16      /* string buffer size */
 877
 878#ifndef CONFIG_NEED_MULTIPLE_NODES
 879
 880extern struct pglist_data contig_page_data;
 881#define NODE_DATA(nid)          (&contig_page_data)
 882#define NODE_MEM_MAP(nid)       mem_map
 883
 884#else /* CONFIG_NEED_MULTIPLE_NODES */
 885
 886#include <asm/mmzone.h>
 887
 888#endif /* !CONFIG_NEED_MULTIPLE_NODES */
 889
 890extern struct pglist_data *first_online_pgdat(void);
 891extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
 892extern struct zone *next_zone(struct zone *zone);
 893
 894/**
 895 * for_each_online_pgdat - helper macro to iterate over all online nodes
 896 * @pgdat - pointer to a pg_data_t variable
 897 */
 898#define for_each_online_pgdat(pgdat)                    \
 899        for (pgdat = first_online_pgdat();              \
 900             pgdat;                                     \
 901             pgdat = next_online_pgdat(pgdat))
 902/**
 903 * for_each_zone - helper macro to iterate over all memory zones
 904 * @zone - pointer to struct zone variable
 905 *
 906 * The user only needs to declare the zone variable, for_each_zone
 907 * fills it in.
 908 */
 909#define for_each_zone(zone)                             \
 910        for (zone = (first_online_pgdat())->node_zones; \
 911             zone;                                      \
 912             zone = next_zone(zone))
 913
 914#define for_each_populated_zone(zone)                   \
 915        for (zone = (first_online_pgdat())->node_zones; \
 916             zone;                                      \
 917             zone = next_zone(zone))                    \
 918                if (!populated_zone(zone))              \
 919                        ; /* do nothing */              \
 920                else
 921
 922static inline struct zone *zonelist_zone(struct zoneref *zoneref)
 923{
 924        return zoneref->zone;
 925}
 926
 927static inline int zonelist_zone_idx(struct zoneref *zoneref)
 928{
 929        return zoneref->zone_idx;
 930}
 931
 932static inline int zonelist_node_idx(struct zoneref *zoneref)
 933{
 934#ifdef CONFIG_NUMA
 935        /* zone_to_nid not available in this context */
 936        return zoneref->zone->node;
 937#else
 938        return 0;
 939#endif /* CONFIG_NUMA */
 940}
 941
 942/**
 943 * 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
 944 * @z - The cursor used as a starting point for the search
 945 * @highest_zoneidx - The zone index of the highest zone to return
 946 * @nodes - An optional nodemask to filter the zonelist with
 947 * @zone - The first suitable zone found is returned via this parameter
 948 *
 949 * This function returns the next zone at or below a given zone index that is
 950 * within the allowed nodemask using a cursor as the starting point for the
 951 * search. The zoneref returned is a cursor that represents the current zone
 952 * being examined. It should be advanced by one before calling
 953 * next_zones_zonelist again.
 954 */
 955struct zoneref *next_zones_zonelist(struct zoneref *z,
 956                                        enum zone_type highest_zoneidx,
 957                                        nodemask_t *nodes,
 958                                        struct zone **zone);
 959
 960/**
 961 * first_zones_zonelist - Returns the first zone at or below highest_zoneidx within the allowed nodemask in a zonelist
 962 * @zonelist - The zonelist to search for a suitable zone
 963 * @highest_zoneidx - The zone index of the highest zone to return
 964 * @nodes - An optional nodemask to filter the zonelist with
 965 * @zone - The first suitable zone found is returned via this parameter
 966 *
 967 * This function returns the first zone at or below a given zone index that is
 968 * within the allowed nodemask. The zoneref returned is a cursor that can be
 969 * used to iterate the zonelist with next_zones_zonelist by advancing it by
 970 * one before calling.
 971 */
 972static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
 973                                        enum zone_type highest_zoneidx,
 974                                        nodemask_t *nodes,
 975                                        struct zone **zone)
 976{
 977        return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
 978                                                                zone);
 979}
 980
 981/**
 982 * 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
 983 * @zone - The current zone in the iterator
 984 * @z - The current pointer within zonelist->zones being iterated
 985 * @zlist - The zonelist being iterated
 986 * @highidx - The zone index of the highest zone to return
 987 * @nodemask - Nodemask allowed by the allocator
 988 *
 989 * This iterator iterates though all zones at or below a given zone index and
 990 * within a given nodemask
 991 */
 992#define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
 993        for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
 994                zone;                                                   \
 995                z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \
 996
 997/**
 998 * for_each_zone_zonelist - helper macro to iterate over valid zones in a zonelist at or below a given zone index
 999 * @zone - The current zone in the iterator
1000 * @z - The current pointer within zonelist->zones being iterated
1001 * @zlist - The zonelist being iterated
1002 * @highidx - The zone index of the highest zone to return
1003 *
1004 * This iterator iterates though all zones at or below a given zone index.
1005 */
1006#define for_each_zone_zonelist(zone, z, zlist, highidx) \
1007        for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)
1008
1009#ifdef CONFIG_SPARSEMEM
1010#include <asm/sparsemem.h>
1011#endif
1012
1013#if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
1014        !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
1015static inline unsigned long early_pfn_to_nid(unsigned long pfn)
1016{
1017        return 0;
1018}
1019#endif
1020
1021#ifdef CONFIG_FLATMEM
1022#define pfn_to_nid(pfn)         (0)
1023#endif
1024
1025#ifdef CONFIG_SPARSEMEM
1026
1027/*
1028 * SECTION_SHIFT                #bits space required to store a section #
1029 *
1030 * PA_SECTION_SHIFT             physical address to/from section number
1031 * PFN_SECTION_SHIFT            pfn to/from section number
1032 */
1033#define SECTIONS_SHIFT          (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
1034
1035#define PA_SECTION_SHIFT        (SECTION_SIZE_BITS)
1036#define PFN_SECTION_SHIFT       (SECTION_SIZE_BITS - PAGE_SHIFT)
1037
1038#define NR_MEM_SECTIONS         (1UL << SECTIONS_SHIFT)
1039
1040#define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
1041#define PAGE_SECTION_MASK       (~(PAGES_PER_SECTION-1))
1042
1043#define SECTION_BLOCKFLAGS_BITS \
1044        ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
1045
1046#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
1047#error Allocator MAX_ORDER exceeds SECTION_SIZE
1048#endif
1049
1050#define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
1051#define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)
1052
1053#define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
1054#define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)
1055
1056struct page;
1057struct page_cgroup;
1058struct mem_section {
1059        /*
1060         * This is, logically, a pointer to an array of struct
1061         * pages.  However, it is stored with some other magic.
1062         * (see sparse.c::sparse_init_one_section())
1063         *
1064         * Additionally during early boot we encode node id of
1065         * the location of the section here to guide allocation.
1066         * (see sparse.c::memory_present())
1067         *
1068         * Making it a UL at least makes someone do a cast
1069         * before using it wrong.
1070         */
1071        unsigned long section_mem_map;
1072
1073        /* See declaration of similar field in struct zone */
1074        unsigned long *pageblock_flags;
1075#ifdef CONFIG_MEMCG
1076        /*
1077         * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
1078         * section. (see memcontrol.h/page_cgroup.h about this.)
1079         */
1080        struct page_cgroup *page_cgroup;
1081        unsigned long pad;
1082#endif
1083};
1084
1085#ifdef CONFIG_SPARSEMEM_EXTREME
1086#define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
1087#else
1088#define SECTIONS_PER_ROOT       1
1089#endif
1090
1091#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
1092#define NR_SECTION_ROOTS        DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
1093#define SECTION_ROOT_MASK       (SECTIONS_PER_ROOT - 1)
1094
1095#ifdef CONFIG_SPARSEMEM_EXTREME
1096extern struct mem_section *mem_section[NR_SECTION_ROOTS];
1097#else
1098extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
1099#endif
1100
1101static inline struct mem_section *__nr_to_section(unsigned long nr)
1102{
1103        if (!mem_section[SECTION_NR_TO_ROOT(nr)])
1104                return NULL;
1105        return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
1106}
1107extern int __section_nr(struct mem_section* ms);
1108extern unsigned long usemap_size(void);
1109
1110/*
1111 * We use the lower bits of the mem_map pointer to store
1112 * a little bit of information.  There should be at least
1113 * 3 bits here due to 32-bit alignment.
1114 */
1115#define SECTION_MARKED_PRESENT  (1UL<<0)
1116#define SECTION_HAS_MEM_MAP     (1UL<<1)
1117#define SECTION_MAP_LAST_BIT    (1UL<<2)
1118#define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
1119#define SECTION_NID_SHIFT       2
1120
1121static inline struct page *__section_mem_map_addr(struct mem_section *section)
1122{
1123        unsigned long map = section->section_mem_map;
1124        map &= SECTION_MAP_MASK;
1125        return (struct page *)map;
1126}
1127
1128static inline int present_section(struct mem_section *section)
1129{
1130        return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
1131}
1132
1133static inline int present_section_nr(unsigned long nr)
1134{
1135        return present_section(__nr_to_section(nr));
1136}
1137
1138static inline int valid_section(struct mem_section *section)
1139{
1140        return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
1141}
1142
1143static inline int valid_section_nr(unsigned long nr)
1144{
1145        return valid_section(__nr_to_section(nr));
1146}
1147
1148static inline struct mem_section *__pfn_to_section(unsigned long pfn)
1149{
1150        return __nr_to_section(pfn_to_section_nr(pfn));
1151}
1152
1153#ifndef CONFIG_HAVE_ARCH_PFN_VALID
1154static inline int pfn_valid(unsigned long pfn)
1155{
1156        if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1157                return 0;
1158        return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
1159}
1160#endif
1161
1162static inline int pfn_present(unsigned long pfn)
1163{
1164        if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
1165                return 0;
1166        return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
1167}
1168
1169/*
1170 * These are _only_ used during initialisation, therefore they
1171 * can use __initdata ...  They could have names to indicate
1172 * this restriction.
1173 */
1174#ifdef CONFIG_NUMA
1175#define pfn_to_nid(pfn)                                                 \
1176({                                                                      \
1177        unsigned long __pfn_to_nid_pfn = (pfn);                         \
1178        page_to_nid(pfn_to_page(__pfn_to_nid_pfn));                     \
1179})
1180#else
1181#define pfn_to_nid(pfn)         (0)
1182#endif
1183
1184#define early_pfn_valid(pfn)    pfn_valid(pfn)
1185void sparse_init(void);
1186#else
1187#define sparse_init()   do {} while (0)
1188#define sparse_index_init(_sec, _nid)  do {} while (0)
1189#endif /* CONFIG_SPARSEMEM */
1190
1191#ifdef CONFIG_NODES_SPAN_OTHER_NODES
1192bool early_pfn_in_nid(unsigned long pfn, int nid);
1193#else
1194#define early_pfn_in_nid(pfn, nid)      (1)
1195#endif
1196
1197#ifndef early_pfn_valid
1198#define early_pfn_valid(pfn)    (1)
1199#endif
1200
1201void memory_present(int nid, unsigned long start, unsigned long end);
1202unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
1203
1204/*
1205 * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
1206 * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
1207 * pfn_valid_within() should be used in this case; we optimise this away
1208 * when we have no holes within a MAX_ORDER_NR_PAGES block.
1209 */
1210#ifdef CONFIG_HOLES_IN_ZONE
1211#define pfn_valid_within(pfn) pfn_valid(pfn)
1212#else
1213#define pfn_valid_within(pfn) (1)
1214#endif
1215
1216#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
1217/*
1218 * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
1219 * associated with it or not. In FLATMEM, it is expected that holes always
1220 * have valid memmap as long as there is valid PFNs either side of the hole.
1221 * In SPARSEMEM, it is assumed that a valid section has a memmap for the
1222 * entire section.
1223 *
1224 * However, an ARM, and maybe other embedded architectures in the future
1225 * free memmap backing holes to save memory on the assumption the memmap is
1226 * never used. The page_zone linkages are then broken even though pfn_valid()
1227 * returns true. A walker of the full memmap must then do this additional
1228 * check to ensure the memmap they are looking at is sane by making sure
1229 * the zone and PFN linkages are still valid. This is expensive, but walkers
1230 * of the full memmap are extremely rare.
1231 */
1232int memmap_valid_within(unsigned long pfn,
1233                                        struct page *page, struct zone *zone);
1234#else
1235static inline int memmap_valid_within(unsigned long pfn,
1236                                        struct page *page, struct zone *zone)
1237{
1238        return 1;
1239}
1240#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
1241
1242#endif /* !__GENERATING_BOUNDS.H */
1243#endif /* !__ASSEMBLY__ */
1244#endif /* _LINUX_MMZONE_H */
1245
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