mmzone.h

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#ifndef _LINUX_MMZONE_H
#define _LINUX_MMZONE_H

#ifndef __ASSEMBLY__
#ifndef __GENERATING_BOUNDS_H

#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/cache.h>
#include <linux/threads.h>
#include <linux/numa.h>
#include <linux/init.h>
#include <linux/seqlock.h>
#include <linux/nodemask.h>
#include <linux/pageblock-flags.h>
#include <generated/bounds.h>
#include <linux/atomic.h>
#include <asm/page.h>

/* Free memory management - zoned buddy allocator.  */
#ifndef CONFIG_FORCE_MAX_ZONEORDER
#define MAX_ORDER 11
#else
#define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
#endif
#define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1))

/*
 * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
 * costly to service.  That is between allocation orders which should
 * coalesce naturally under reasonable reclaim pressure and those which
 * will not.
 */
#define PAGE_ALLOC_COSTLY_ORDER 3

enum {
    MIGRATE_UNMOVABLE,
    MIGRATE_RECLAIMABLE,
    MIGRATE_MOVABLE,
    MIGRATE_PCPTYPES,   /* the number of types on the pcp lists */
    MIGRATE_RESERVE = MIGRATE_PCPTYPES,
#ifdef CONFIG_CMA
    /*
     * MIGRATE_CMA migration type is designed to mimic the way
     * ZONE_MOVABLE works.  Only movable pages can be allocated
     * from MIGRATE_CMA pageblocks and page allocator never
     * implicitly change migration type of MIGRATE_CMA pageblock.
     *
     * The way to use it is to change migratetype of a range of
     * pageblocks to MIGRATE_CMA which can be done by
     * __free_pageblock_cma() function.  What is important though
     * is that a range of pageblocks must be aligned to
     * MAX_ORDER_NR_PAGES should biggest page be bigger then
     * a single pageblock.
     */
    MIGRATE_CMA,
#endif
    MIGRATE_ISOLATE,    /* can't allocate from here */
    MIGRATE_TYPES
};

#ifdef CONFIG_CMA
#  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)
#  define cma_wmark_pages(zone) zone->min_cma_pages
#else
#  define is_migrate_cma(migratetype) false
#  define cma_wmark_pages(zone) 0
#endif

#define for_each_migratetype_order(order, type) \
    for (order = 0; order < MAX_ORDER; order++) \
        for (type = 0; type < MIGRATE_TYPES; type++)

extern int page_group_by_mobility_disabled;

static inline int get_pageblock_migratetype(struct page *page)
{
    return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
}

struct free_area {
    struct list_head    free_list[MIGRATE_TYPES];
    unsigned long       nr_free;
};

struct pglist_data;

/*
 * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
 * So add a wild amount of padding here to ensure that they fall into separate
 * cachelines.  There are very few zone structures in the machine, so space
 * consumption is not a concern here.
 */
#if defined(CONFIG_SMP)
struct zone_padding {
    char x[0];
} ____cacheline_internodealigned_in_smp;
#define ZONE_PADDING(name)  struct zone_padding name;
#else
#define ZONE_PADDING(name)
#endif

enum zone_stat_item {
    /* First 128 byte cacheline (assuming 64 bit words) */
    NR_FREE_PAGES,
    NR_LRU_BASE,
    NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
    NR_ACTIVE_ANON,     /*  "     "     "   "       "         */
    NR_INACTIVE_FILE,   /*  "     "     "   "       "         */
    NR_ACTIVE_FILE,     /*  "     "     "   "       "         */
    NR_UNEVICTABLE,     /*  "     "     "   "       "         */
    NR_MLOCK,       /* mlock()ed pages found and moved off LRU */
    NR_ANON_PAGES,  /* Mapped anonymous pages */
    NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
               only modified from process context */
    NR_FILE_PAGES,
    NR_FILE_DIRTY,
    NR_WRITEBACK,
    NR_SLAB_RECLAIMABLE,
    NR_SLAB_UNRECLAIMABLE,
    NR_PAGETABLE,       /* used for pagetables */
    NR_KERNEL_STACK,
    /* Second 128 byte cacheline */
    NR_UNSTABLE_NFS,    /* NFS unstable pages */
    NR_BOUNCE,
    NR_VMSCAN_WRITE,
    NR_VMSCAN_IMMEDIATE,    /* Prioritise for reclaim when writeback ends */
    NR_WRITEBACK_TEMP,  /* Writeback using temporary buffers */
    NR_ISOLATED_ANON,   /* Temporary isolated pages from anon lru */
    NR_ISOLATED_FILE,   /* Temporary isolated pages from file lru */
    NR_SHMEM,       /* shmem pages (included tmpfs/GEM pages) */
    NR_DIRTIED,     /* page dirtyings since bootup */
    NR_WRITTEN,     /* page writings since bootup */
#ifdef CONFIG_NUMA
    NUMA_HIT,       /* allocated in intended node */
    NUMA_MISS,      /* allocated in non intended node */
    NUMA_FOREIGN,       /* was intended here, hit elsewhere */
    NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
    NUMA_LOCAL,     /* allocation from local node */
    NUMA_OTHER,     /* allocation from other node */
#endif
    NR_ANON_TRANSPARENT_HUGEPAGES,
    NR_FREE_CMA_PAGES,
    NR_VM_ZONE_STAT_ITEMS };

/*
 * We do arithmetic on the LRU lists in various places in the code,
 * so it is important to keep the active lists LRU_ACTIVE higher in
 * the array than the corresponding inactive lists, and to keep
 * the *_FILE lists LRU_FILE higher than the corresponding _ANON lists.
 *
 * This has to be kept in sync with the statistics in zone_stat_item
 * above and the descriptions in vmstat_text in mm/vmstat.c
 */
#define LRU_BASE 0
#define LRU_ACTIVE 1
#define LRU_FILE 2

enum lru_list {
    LRU_INACTIVE_ANON = LRU_BASE,
    LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
    LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
    LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
    LRU_UNEVICTABLE,
    NR_LRU_LISTS
};

#define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++)

#define for_each_evictable_lru(lru) for (lru = 0; lru <= LRU_ACTIVE_FILE; lru++)

static inline int is_file_lru(enum lru_list lru)
{
    return (lru == LRU_INACTIVE_FILE || lru == LRU_ACTIVE_FILE);
}

static inline int is_active_lru(enum lru_list lru)
{
    return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
}

static inline int is_unevictable_lru(enum lru_list lru)
{
    return (lru == LRU_UNEVICTABLE);
}

struct zone_reclaim_stat {
    /*
     * The pageout code in vmscan.c keeps track of how many of the
     * mem/swap backed and file backed pages are referenced.
     * The higher the rotated/scanned ratio, the more valuable
     * that cache is.
     *
     * The anon LRU stats live in [0], file LRU stats in [1]
     */
    unsigned long       recent_rotated[2];
    unsigned long       recent_scanned[2];
};

struct lruvec {
    struct list_head lists[NR_LRU_LISTS];
    struct zone_reclaim_stat reclaim_stat;
#ifdef CONFIG_MEMCG
    struct zone *zone;
#endif
};

/* Mask used at gathering information at once (see memcontrol.c) */
#define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
#define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
#define LRU_ALL      ((1 << NR_LRU_LISTS) - 1)

/* Isolate clean file */
#define ISOLATE_CLEAN       ((__force isolate_mode_t)0x1)
/* Isolate unmapped file */
#define ISOLATE_UNMAPPED    ((__force isolate_mode_t)0x2)
/* Isolate for asynchronous migration */
#define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x4)
/* Isolate unevictable pages */
#define ISOLATE_UNEVICTABLE ((__force isolate_mode_t)0x8)

/* LRU Isolation modes. */
typedef unsigned __bitwise__ isolate_mode_t;

enum zone_watermarks {
    WMARK_MIN,
    WMARK_LOW,
    WMARK_HIGH,
    NR_WMARK
};

#define min_wmark_pages(z) (z->watermark[WMARK_MIN])
#define low_wmark_pages(z) (z->watermark[WMARK_LOW])
#define high_wmark_pages(z) (z->watermark[WMARK_HIGH])

struct per_cpu_pages {
    int count;      /* number of pages in the list */
    int high;       /* high watermark, emptying needed */
    int batch;      /* chunk size for buddy add/remove */

    /* Lists of pages, one per migrate type stored on the pcp-lists */
    struct list_head lists[MIGRATE_PCPTYPES];
};

struct per_cpu_pageset {
    struct per_cpu_pages pcp;
#ifdef CONFIG_NUMA
    s8 expire;
#endif
#ifdef CONFIG_SMP
    s8 stat_threshold;
    s8 vm_stat_diff[NR_VM_ZONE_STAT_ITEMS];
#endif
};

#endif /* !__GENERATING_BOUNDS.H */

enum zone_type {
#ifdef CONFIG_ZONE_DMA
    /*
     * ZONE_DMA is used when there are devices that are not able
     * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
     * carve out the portion of memory that is needed for these devices.
     * The range is arch specific.
     *
     * Some examples
     *
     * Architecture     Limit
     * ---------------------------
     * parisc, ia64, sparc  <4G
     * s390         <2G
     * arm          Various
     * alpha        Unlimited or 0-16MB.
     *
     * i386, x86_64 and multiple other arches
     *          <16M.
     */
    ZONE_DMA,
#endif
#ifdef CONFIG_ZONE_DMA32
    /*
     * x86_64 needs two ZONE_DMAs because it supports devices that are
     * only able to do DMA to the lower 16M but also 32 bit devices that
     * can only do DMA areas below 4G.
     */
    ZONE_DMA32,
#endif
    /*
     * Normal addressable memory is in ZONE_NORMAL. DMA operations can be
     * performed on pages in ZONE_NORMAL if the DMA devices support
     * transfers to all addressable memory.
     */
    ZONE_NORMAL,
#ifdef CONFIG_HIGHMEM
    /*
     * A memory area that is only addressable by the kernel through
     * mapping portions into its own address space. This is for example
     * used by i386 to allow the kernel to address the memory beyond
     * 900MB. The kernel will set up special mappings (page
     * table entries on i386) for each page that the kernel needs to
     * access.
     */
    ZONE_HIGHMEM,
#endif
    ZONE_MOVABLE,
    __MAX_NR_ZONES
};

#ifndef __GENERATING_BOUNDS_H

/*
 * When a memory allocation must conform to specific limitations (such
 * as being suitable for DMA) the caller will pass in hints to the
 * allocator in the gfp_mask, in the zone modifier bits.  These bits
 * are used to select a priority ordered list of memory zones which
 * match the requested limits. See gfp_zone() in include/linux/gfp.h
 */

#if MAX_NR_ZONES < 2
#define ZONES_SHIFT 0
#elif MAX_NR_ZONES <= 2
#define ZONES_SHIFT 1
#elif MAX_NR_ZONES <= 4
#define ZONES_SHIFT 2
#else
#error ZONES_SHIFT -- too many zones configured adjust calculation
#endif

struct zone {
    /* Fields commonly accessed by the page allocator */

    /* zone watermarks, access with *_wmark_pages(zone) macros */
    unsigned long watermark[NR_WMARK];

    /*
     * When free pages are below this point, additional steps are taken
     * when reading the number of free pages to avoid per-cpu counter
     * drift allowing watermarks to be breached
     */
    unsigned long percpu_drift_mark;

    /*
     * We don't know if the memory that we're going to allocate will be freeable
     * or/and it will be released eventually, so to avoid totally wasting several
     * GB of ram we must reserve some of the lower zone memory (otherwise we risk
     * to run OOM on the lower zones despite there's tons of freeable ram
     * on the higher zones). This array is recalculated at runtime if the
     * sysctl_lowmem_reserve_ratio sysctl changes.
     */
    unsigned long       lowmem_reserve[MAX_NR_ZONES];

    /*
     * This is a per-zone reserve of pages that should not be
     * considered dirtyable memory.
     */
    unsigned long       dirty_balance_reserve;

#ifdef CONFIG_NUMA
    int node;
    /*
     * zone reclaim becomes active if more unmapped pages exist.
     */
    unsigned long       min_unmapped_pages;
    unsigned long       min_slab_pages;
#endif
    struct per_cpu_pageset __percpu *pageset;
    /*
     * free areas of different sizes
     */
    spinlock_t      lock;
    int                     all_unreclaimable; /* All pages pinned */
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
    /* Set to true when the PG_migrate_skip bits should be cleared */
    bool            compact_blockskip_flush;

    /* pfns where compaction scanners should start */
    unsigned long       compact_cached_free_pfn;
    unsigned long       compact_cached_migrate_pfn;
#endif
#ifdef CONFIG_MEMORY_HOTPLUG
    /* see spanned/present_pages for more description */
    seqlock_t       span_seqlock;
#endif
#ifdef CONFIG_CMA
    /*
     * CMA needs to increase watermark levels during the allocation
     * process to make sure that the system is not starved.
     */
    unsigned long       min_cma_pages;
#endif
    struct free_area    free_area[MAX_ORDER];

#ifndef CONFIG_SPARSEMEM
    /*
     * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
     * In SPARSEMEM, this map is stored in struct mem_section
     */
    unsigned long       *pageblock_flags;
#endif /* CONFIG_SPARSEMEM */

#ifdef CONFIG_COMPACTION
    /*
     * On compaction failure, 1<<compact_defer_shift compactions
     * are skipped before trying again. The number attempted since
     * last failure is tracked with compact_considered.
     */
    unsigned int        compact_considered;
    unsigned int        compact_defer_shift;
    int         compact_order_failed;
#endif

    ZONE_PADDING(_pad1_)

    /* Fields commonly accessed by the page reclaim scanner */
    spinlock_t      lru_lock;
    struct lruvec       lruvec;

    unsigned long       pages_scanned;     /* since last reclaim */
    unsigned long       flags;         /* zone flags, see below */

    /* Zone statistics */
    atomic_long_t       vm_stat[NR_VM_ZONE_STAT_ITEMS];

    /*
     * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
     * this zone's LRU.  Maintained by the pageout code.
     */
    unsigned int inactive_ratio;


    ZONE_PADDING(_pad2_)
    /* Rarely used or read-mostly fields */

    /*
     * wait_table       -- the array holding the hash table
     * wait_table_hash_nr_entries   -- the size of the hash table array
     * wait_table_bits  -- wait_table_size == (1 << wait_table_bits)
     *
     * The purpose of all these is to keep track of the people
     * waiting for a page to become available and make them
     * runnable again when possible. The trouble is that this
     * consumes a lot of space, especially when so few things
     * wait on pages at a given time. So instead of using
     * per-page waitqueues, we use a waitqueue hash table.
     *
     * The bucket discipline is to sleep on the same queue when
     * colliding and wake all in that wait queue when removing.
     * When something wakes, it must check to be sure its page is
     * truly available, a la thundering herd. The cost of a
     * collision is great, but given the expected load of the
     * table, they should be so rare as to be outweighed by the
     * benefits from the saved space.
     *
     * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
     * primary users of these fields, and in mm/page_alloc.c
     * free_area_init_core() performs the initialization of them.
     */
    wait_queue_head_t   * wait_table;
    unsigned long       wait_table_hash_nr_entries;
    unsigned long       wait_table_bits;

    /*
     * Discontig memory support fields.
     */
    struct pglist_data  *zone_pgdat;
    /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
    unsigned long       zone_start_pfn;

    /*
     * zone_start_pfn, spanned_pages and present_pages are all
     * protected by span_seqlock.  It is a seqlock because it has
     * to be read outside of zone->lock, and it is done in the main
     * allocator path.  But, it is written quite infrequently.
     *
     * The lock is declared along with zone->lock because it is
     * frequently read in proximity to zone->lock.  It's good to
     * give them a chance of being in the same cacheline.
     */
    unsigned long       spanned_pages;  /* total size, including holes */
    unsigned long       present_pages;  /* amount of memory (excluding holes) */

    /*
     * rarely used fields:
     */
    const char      *name;
#ifdef CONFIG_MEMORY_ISOLATION
    /*
     * the number of MIGRATE_ISOLATE *pageblock*.
     * We need this for free page counting. Look at zone_watermark_ok_safe.
     * It's protected by zone->lock
     */
    int     nr_pageblock_isolate;
#endif
} ____cacheline_internodealigned_in_smp;

typedef enum {
    ZONE_RECLAIM_LOCKED,        /* prevents concurrent reclaim */
    ZONE_OOM_LOCKED,        /* zone is in OOM killer zonelist */
    ZONE_CONGESTED,         /* zone has many dirty pages backed by
                     * a congested BDI
                     */
} zone_flags_t;

static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
{
    set_bit(flag, &zone->flags);
}

static inline int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
{
    return test_and_set_bit(flag, &zone->flags);
}

static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
{
    clear_bit(flag, &zone->flags);
}

static inline int zone_is_reclaim_congested(const struct zone *zone)
{
    return test_bit(ZONE_CONGESTED, &zone->flags);
}

static inline int zone_is_reclaim_locked(const struct zone *zone)
{
    return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
}

static inline int zone_is_oom_locked(const struct zone *zone)
{
    return test_bit(ZONE_OOM_LOCKED, &zone->flags);
}

/*
 * The "priority" of VM scanning is how much of the queues we will scan in one
 * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
 * queues ("queue_length >> 12") during an aging round.
 */
#define DEF_PRIORITY 12

/* Maximum number of zones on a zonelist */
#define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)

#ifdef CONFIG_NUMA

/*
 * The NUMA zonelists are doubled because we need zonelists that restrict the
 * allocations to a single node for GFP_THISNODE.
 *
 * [0]  : Zonelist with fallback
 * [1]  : No fallback (GFP_THISNODE)
 */
#define MAX_ZONELISTS 2


/*
 * We cache key information from each zonelist for smaller cache
 * footprint when scanning for free pages in get_page_from_freelist().
 *
 * 1) The BITMAP fullzones tracks which zones in a zonelist have come
 *    up short of free memory since the last time (last_fullzone_zap)
 *    we zero'd fullzones.
 * 2) The array z_to_n[] maps each zone in the zonelist to its node
 *    id, so that we can efficiently evaluate whether that node is
 *    set in the current tasks mems_allowed.
 *
 * Both fullzones and z_to_n[] are one-to-one with the zonelist,
 * indexed by a zones offset in the zonelist zones[] array.
 *
 * The get_page_from_freelist() routine does two scans.  During the
 * first scan, we skip zones whose corresponding bit in 'fullzones'
 * is set or whose corresponding node in current->mems_allowed (which
 * comes from cpusets) is not set.  During the second scan, we bypass
 * this zonelist_cache, to ensure we look methodically at each zone.
 *
 * Once per second, we zero out (zap) fullzones, forcing us to
 * reconsider nodes that might have regained more free memory.
 * The field last_full_zap is the time we last zapped fullzones.
 *
 * This mechanism reduces the amount of time we waste repeatedly
 * reexaming zones for free memory when they just came up low on
 * memory momentarilly ago.
 *
 * The zonelist_cache struct members logically belong in struct
 * zonelist.  However, the mempolicy zonelists constructed for
 * MPOL_BIND are intentionally variable length (and usually much
 * shorter).  A general purpose mechanism for handling structs with
 * multiple variable length members is more mechanism than we want
 * here.  We resort to some special case hackery instead.
 *
 * The MPOL_BIND zonelists don't need this zonelist_cache (in good
 * part because they are shorter), so we put the fixed length stuff
 * at the front of the zonelist struct, ending in a variable length
 * zones[], as is needed by MPOL_BIND.
 *
 * Then we put the optional zonelist cache on the end of the zonelist
 * struct.  This optional stuff is found by a 'zlcache_ptr' pointer in
 * the fixed length portion at the front of the struct.  This pointer
 * both enables us to find the zonelist cache, and in the case of
 * MPOL_BIND zonelists, (which will just set the zlcache_ptr to NULL)
 * to know that the zonelist cache is not there.
 *
 * The end result is that struct zonelists come in two flavors:
 *  1) The full, fixed length version, shown below, and
 *  2) The custom zonelists for MPOL_BIND.
 * The custom MPOL_BIND zonelists have a NULL zlcache_ptr and no zlcache.
 *
 * Even though there may be multiple CPU cores on a node modifying
 * fullzones or last_full_zap in the same zonelist_cache at the same
 * time, we don't lock it.  This is just hint data - if it is wrong now
 * and then, the allocator will still function, perhaps a bit slower.
 */


struct zonelist_cache {
    unsigned short z_to_n[MAX_ZONES_PER_ZONELIST];      /* zone->nid */
    DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST);  /* zone full? */
    unsigned long last_full_zap;        /* when last zap'd (jiffies) */
};
#else
#define MAX_ZONELISTS 1
struct zonelist_cache;
#endif

/*
 * This struct contains information about a zone in a zonelist. It is stored
 * here to avoid dereferences into large structures and lookups of tables
 */
struct zoneref {
    struct zone *zone;  /* Pointer to actual zone */
    int zone_idx;       /* zone_idx(zoneref->zone) */
};

/*
 * One allocation request operates on a zonelist. A zonelist
 * is a list of zones, the first one is the 'goal' of the
 * allocation, the other zones are fallback zones, in decreasing
 * priority.
 *
 * If zlcache_ptr is not NULL, then it is just the address of zlcache,
 * as explained above.  If zlcache_ptr is NULL, there is no zlcache.
 * *
 * To speed the reading of the zonelist, the zonerefs contain the zone index
 * of the entry being read. Helper functions to access information given
 * a struct zoneref are
 *
 * zonelist_zone()  - Return the struct zone * for an entry in _zonerefs
 * zonelist_zone_idx()  - Return the index of the zone for an entry
 * zonelist_node_idx()  - Return the index of the node for an entry
 */
struct zonelist {
    struct zonelist_cache *zlcache_ptr;          // NULL or &zlcache
    struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
#ifdef CONFIG_NUMA
    struct zonelist_cache zlcache;               // optional ...
#endif
};

#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
struct node_active_region {
    unsigned long start_pfn;
    unsigned long end_pfn;
    int nid;
};
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */

#ifndef CONFIG_DISCONTIGMEM
/* The array of struct pages - for discontigmem use pgdat->lmem_map */
extern struct page *mem_map;
#endif

/*
 * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
 * (mostly NUMA machines?) to denote a higher-level memory zone than the
 * zone denotes.
 *
 * On NUMA machines, each NUMA node would have a pg_data_t to describe
 * it's memory layout.
 *
 * Memory statistics and page replacement data structures are maintained on a
 * per-zone basis.
 */
struct bootmem_data;
typedef struct pglist_data {
    struct zone node_zones[MAX_NR_ZONES];
    struct zonelist node_zonelists[MAX_ZONELISTS];
    int nr_zones;
#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
    struct page *node_mem_map;
#ifdef CONFIG_MEMCG
    struct page_cgroup *node_page_cgroup;
#endif
#endif
#ifndef CONFIG_NO_BOOTMEM
    struct bootmem_data *bdata;
#endif
#ifdef CONFIG_MEMORY_HOTPLUG
    /*
     * Must be held any time you expect node_start_pfn, node_present_pages
     * or node_spanned_pages stay constant.  Holding this will also
     * guarantee that any pfn_valid() stays that way.
     *
     * Nests above zone->lock and zone->size_seqlock.
     */
    spinlock_t node_size_lock;
#endif
    unsigned long node_start_pfn;
    unsigned long node_present_pages; /* total number of physical pages */
    unsigned long node_spanned_pages; /* total size of physical page
                         range, including holes */
    int node_id;
    nodemask_t reclaim_nodes;   /* Nodes allowed to reclaim from */
    wait_queue_head_t kswapd_wait;
    wait_queue_head_t pfmemalloc_wait;
    struct task_struct *kswapd; /* Protected by lock_memory_hotplug() */
    int kswapd_max_order;
    enum zone_type classzone_idx;
} pg_data_t;

#define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
#define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
#ifdef CONFIG_FLAT_NODE_MEM_MAP
#define pgdat_page_nr(pgdat, pagenr)    ((pgdat)->node_mem_map + (pagenr))
#else
#define pgdat_page_nr(pgdat, pagenr)    pfn_to_page((pgdat)->node_start_pfn + (pagenr))
#endif
#define nid_page_nr(nid, pagenr)    pgdat_page_nr(NODE_DATA(nid),(pagenr))

#define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn)

#define node_end_pfn(nid) ({\
    pg_data_t *__pgdat = NODE_DATA(nid);\
    __pgdat->node_start_pfn + __pgdat->node_spanned_pages;\
})

#include <linux/memory_hotplug.h>

extern struct mutex zonelists_mutex;
void build_all_zonelists(pg_data_t *pgdat, struct zone *zone);
void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx);
bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
        int classzone_idx, int alloc_flags);
bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
        int classzone_idx, int alloc_flags);
enum memmap_context {
    MEMMAP_EARLY,
    MEMMAP_HOTPLUG,
};
extern int init_currently_empty_zone(struct zone *zone, unsigned long start_pfn,
                     unsigned long size,
                     enum memmap_context context);

extern void lruvec_init(struct lruvec *lruvec);

static inline struct zone *lruvec_zone(struct lruvec *lruvec)
{
#ifdef CONFIG_MEMCG
    return lruvec->zone;
#else
    return container_of(lruvec, struct zone, lruvec);
#endif
}

#ifdef CONFIG_HAVE_MEMORY_PRESENT
void memory_present(int nid, unsigned long start, unsigned long end);
#else
static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
#endif

#ifdef CONFIG_HAVE_MEMORYLESS_NODES
int local_memory_node(int node_id);
#else
static inline int local_memory_node(int node_id) { return node_id; };
#endif

#ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
#endif

/*
 * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
 */
#define zone_idx(zone)      ((zone) - (zone)->zone_pgdat->node_zones)

static inline int populated_zone(struct zone *zone)
{
    return (!!zone->present_pages);
}

extern int movable_zone;

static inline int zone_movable_is_highmem(void)
{
#if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
    return movable_zone == ZONE_HIGHMEM;
#else
    return 0;
#endif
}

static inline int is_highmem_idx(enum zone_type idx)
{
#ifdef CONFIG_HIGHMEM
    return (idx == ZONE_HIGHMEM ||
        (idx == ZONE_MOVABLE && zone_movable_is_highmem()));
#else
    return 0;
#endif
}

static inline int is_normal_idx(enum zone_type idx)
{
    return (idx == ZONE_NORMAL);
}

static inline int is_highmem(struct zone *zone)
{
#ifdef CONFIG_HIGHMEM
    int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
    return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
           (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
        zone_movable_is_highmem());
#else
    return 0;
#endif
}

static inline int is_normal(struct zone *zone)
{
    return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
}

static inline int is_dma32(struct zone *zone)
{
#ifdef CONFIG_ZONE_DMA32
    return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
#else
    return 0;
#endif
}

static inline int is_dma(struct zone *zone)
{
#ifdef CONFIG_ZONE_DMA
    return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
#else
    return 0;
#endif
}

/* These two functions are used to setup the per zone pages min values */
struct ctl_table;
int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
                    void __user *, size_t *, loff_t *);
extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
                    void __user *, size_t *, loff_t *);
int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
                    void __user *, size_t *, loff_t *);
int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
            void __user *, size_t *, loff_t *);
int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
            void __user *, size_t *, loff_t *);

extern int numa_zonelist_order_handler(struct ctl_table *, int,
            void __user *, size_t *, loff_t *);
extern char numa_zonelist_order[];
#define NUMA_ZONELIST_ORDER_LEN 16  /* string buffer size */

#ifndef CONFIG_NEED_MULTIPLE_NODES

extern struct pglist_data contig_page_data;
#define NODE_DATA(nid)      (&contig_page_data)
#define NODE_MEM_MAP(nid)   mem_map

#else /* CONFIG_NEED_MULTIPLE_NODES */

#include <asm/mmzone.h>

#endif /* !CONFIG_NEED_MULTIPLE_NODES */

extern struct pglist_data *first_online_pgdat(void);
extern struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
extern struct zone *next_zone(struct zone *zone);

#define for_each_online_pgdat(pgdat)            \
    for (pgdat = first_online_pgdat();      \
         pgdat;                 \
         pgdat = next_online_pgdat(pgdat))

#define for_each_zone(zone)                 \
    for (zone = (first_online_pgdat())->node_zones; \
         zone;                  \
         zone = next_zone(zone))

#define for_each_populated_zone(zone)               \
    for (zone = (first_online_pgdat())->node_zones; \
         zone;                  \
         zone = next_zone(zone))            \
        if (!populated_zone(zone))      \
            ; /* do nothing */      \
        else

static inline struct zone *zonelist_zone(struct zoneref *zoneref)
{
    return zoneref->zone;
}

static inline int zonelist_zone_idx(struct zoneref *zoneref)
{
    return zoneref->zone_idx;
}

static inline int zonelist_node_idx(struct zoneref *zoneref)
{
#ifdef CONFIG_NUMA
    /* zone_to_nid not available in this context */
    return zoneref->zone->node;
#else
    return 0;
#endif /* CONFIG_NUMA */
}

struct zoneref *next_zones_zonelist(struct zoneref *z,
                    enum zone_type highest_zoneidx,
                    nodemask_t *nodes,
                    struct zone **zone);

static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist,
                    enum zone_type highest_zoneidx,
                    nodemask_t *nodes,
                    struct zone **zone)
{
    return next_zones_zonelist(zonelist->_zonerefs, highest_zoneidx, nodes,
                                zone);
}

#define for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, nodemask) \
    for (z = first_zones_zonelist(zlist, highidx, nodemask, &zone); \
        zone;                           \
        z = next_zones_zonelist(++z, highidx, nodemask, &zone)) \


#define for_each_zone_zonelist(zone, z, zlist, highidx) \
    for_each_zone_zonelist_nodemask(zone, z, zlist, highidx, NULL)

#ifdef CONFIG_SPARSEMEM
#include <asm/sparsemem.h>
#endif

#if !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID) && \
    !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
static inline unsigned long early_pfn_to_nid(unsigned long pfn)
{
    return 0;
}
#endif

#ifdef CONFIG_FLATMEM
#define pfn_to_nid(pfn)     (0)
#endif

#ifdef CONFIG_SPARSEMEM

/*
 * SECTION_SHIFT            #bits space required to store a section #
 *
 * PA_SECTION_SHIFT     physical address to/from section number
 * PFN_SECTION_SHIFT        pfn to/from section number
 */
#define SECTIONS_SHIFT      (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

#define PA_SECTION_SHIFT    (SECTION_SIZE_BITS)
#define PFN_SECTION_SHIFT   (SECTION_SIZE_BITS - PAGE_SHIFT)

#define NR_MEM_SECTIONS     (1UL << SECTIONS_SHIFT)

#define PAGES_PER_SECTION       (1UL << PFN_SECTION_SHIFT)
#define PAGE_SECTION_MASK   (~(PAGES_PER_SECTION-1))

#define SECTION_BLOCKFLAGS_BITS \
    ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)

#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
#error Allocator MAX_ORDER exceeds SECTION_SIZE
#endif

#define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT)
#define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT)

#define SECTION_ALIGN_UP(pfn)   (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK)
#define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK)

struct page;
struct page_cgroup;
struct mem_section {
    /*
     * This is, logically, a pointer to an array of struct
     * pages.  However, it is stored with some other magic.
     * (see sparse.c::sparse_init_one_section())
     *
     * Additionally during early boot we encode node id of
     * the location of the section here to guide allocation.
     * (see sparse.c::memory_present())
     *
     * Making it a UL at least makes someone do a cast
     * before using it wrong.
     */
    unsigned long section_mem_map;

    /* See declaration of similar field in struct zone */
    unsigned long *pageblock_flags;
#ifdef CONFIG_MEMCG
    /*
     * If !SPARSEMEM, pgdat doesn't have page_cgroup pointer. We use
     * section. (see memcontrol.h/page_cgroup.h about this.)
     */
    struct page_cgroup *page_cgroup;
    unsigned long pad;
#endif
};

#ifdef CONFIG_SPARSEMEM_EXTREME
#define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
#else
#define SECTIONS_PER_ROOT   1
#endif

#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
#define NR_SECTION_ROOTS    DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
#define SECTION_ROOT_MASK   (SECTIONS_PER_ROOT - 1)

#ifdef CONFIG_SPARSEMEM_EXTREME
extern struct mem_section *mem_section[NR_SECTION_ROOTS];
#else
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif

static inline struct mem_section *__nr_to_section(unsigned long nr)
{
    if (!mem_section[SECTION_NR_TO_ROOT(nr)])
        return NULL;
    return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
}
extern int __section_nr(struct mem_section* ms);
extern unsigned long usemap_size(void);

/*
 * We use the lower bits of the mem_map pointer to store
 * a little bit of information.  There should be at least
 * 3 bits here due to 32-bit alignment.
 */
#define SECTION_MARKED_PRESENT  (1UL<<0)
#define SECTION_HAS_MEM_MAP (1UL<<1)
#define SECTION_MAP_LAST_BIT    (1UL<<2)
#define SECTION_MAP_MASK    (~(SECTION_MAP_LAST_BIT-1))
#define SECTION_NID_SHIFT   2

static inline struct page *__section_mem_map_addr(struct mem_section *section)
{
    unsigned long map = section->section_mem_map;
    map &= SECTION_MAP_MASK;
    return (struct page *)map;
}

static inline int present_section(struct mem_section *section)
{
    return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
}

static inline int present_section_nr(unsigned long nr)
{
    return present_section(__nr_to_section(nr));
}

static inline int valid_section(struct mem_section *section)
{
    return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
}

static inline int valid_section_nr(unsigned long nr)
{
    return valid_section(__nr_to_section(nr));
}

static inline struct mem_section *__pfn_to_section(unsigned long pfn)
{
    return __nr_to_section(pfn_to_section_nr(pfn));
}

#ifndef CONFIG_HAVE_ARCH_PFN_VALID
static inline int pfn_valid(unsigned long pfn)
{
    if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
        return 0;
    return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
}
#endif

static inline int pfn_present(unsigned long pfn)
{
    if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
        return 0;
    return present_section(__nr_to_section(pfn_to_section_nr(pfn)));
}

/*
 * These are _only_ used during initialisation, therefore they
 * can use __initdata ...  They could have names to indicate
 * this restriction.
 */
#ifdef CONFIG_NUMA
#define pfn_to_nid(pfn)                         \
({                                  \
    unsigned long __pfn_to_nid_pfn = (pfn);             \
    page_to_nid(pfn_to_page(__pfn_to_nid_pfn));         \
})
#else
#define pfn_to_nid(pfn)     (0)
#endif

#define early_pfn_valid(pfn)    pfn_valid(pfn)
void sparse_init(void);
#else
#define sparse_init()   do {} while (0)
#define sparse_index_init(_sec, _nid)  do {} while (0)
#endif /* CONFIG_SPARSEMEM */

#ifdef CONFIG_NODES_SPAN_OTHER_NODES
bool early_pfn_in_nid(unsigned long pfn, int nid);
#else
#define early_pfn_in_nid(pfn, nid)  (1)
#endif

#ifndef early_pfn_valid
#define early_pfn_valid(pfn)    (1)
#endif

void memory_present(int nid, unsigned long start, unsigned long end);
unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);

/*
 * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
 * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
 * pfn_valid_within() should be used in this case; we optimise this away
 * when we have no holes within a MAX_ORDER_NR_PAGES block.
 */
#ifdef CONFIG_HOLES_IN_ZONE
#define pfn_valid_within(pfn) pfn_valid(pfn)
#else
#define pfn_valid_within(pfn) (1)
#endif

#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
/*
 * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
 * associated with it or not. In FLATMEM, it is expected that holes always
 * have valid memmap as long as there is valid PFNs either side of the hole.
 * In SPARSEMEM, it is assumed that a valid section has a memmap for the
 * entire section.
 *
 * However, an ARM, and maybe other embedded architectures in the future
 * free memmap backing holes to save memory on the assumption the memmap is
 * never used. The page_zone linkages are then broken even though pfn_valid()
 * returns true. A walker of the full memmap must then do this additional
 * check to ensure the memmap they are looking at is sane by making sure
 * the zone and PFN linkages are still valid. This is expensive, but walkers
 * of the full memmap are extremely rare.
 */
int memmap_valid_within(unsigned long pfn,
                    struct page *page, struct zone *zone);
#else
static inline int memmap_valid_within(unsigned long pfn,
                    struct page *page, struct zone *zone)
{
    return 1;
}
#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */

#endif /* !__GENERATING_BOUNDS.H */
#endif /* !__ASSEMBLY__ */
#endif /* _LINUX_MMZONE_H */