/*
 * linux/mm/slab.c
 * Written by Mark Hemment, 1996/97.
 * (markhe@nextd.demon.co.uk)
 *
 * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
 *
 * Major cleanup, different bufctl logic, per-cpu arrays
 *      (c) 2000 Manfred Spraul
 *
 * Cleanup, make the head arrays unconditional, preparation for NUMA
 *      (c) 2002 Manfred Spraul
 *
 * An implementation of the Slab Allocator as described in outline in;
 *      UNIX Internals: The New Frontiers by Uresh Vahalia
 *      Pub: Prentice Hall      ISBN 0-13-101908-2
 * or with a little more detail in;
 *      The Slab Allocator: An Object-Caching Kernel Memory Allocator
 *      Jeff Bonwick (Sun Microsystems).
 *      Presented at: USENIX Summer 1994 Technical Conference
 *
 * The memory is organized in caches, one cache for each object type.
 * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
 * Each cache consists out of many slabs (they are small (usually one
 * page long) and always contiguous), and each slab contains multiple
 * initialized objects.
 *
 * This means, that your constructor is used only for newly allocated
 * slabs and you must pass objects with the same initializations to
 * kmem_cache_free.
 *
 * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
 * normal). If you need a special memory type, then must create a new
 * cache for that memory type.
 *
 * In order to reduce fragmentation, the slabs are sorted in 3 groups:
 *   full slabs with 0 free objects
 *   partial slabs
 *   empty slabs with no allocated objects
 *
 * If partial slabs exist, then new allocations come from these slabs,
 * otherwise from empty slabs or new slabs are allocated.
 *
 * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
 * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
 *
 * Each cache has a short per-cpu head array, most allocs
 * and frees go into that array, and if that array overflows, then 1/2
 * of the entries in the array are given back into the global cache.
 * The head array is strictly LIFO and should improve the cache hit rates.
 * On SMP, it additionally reduces the spinlock operations.
 *
 * The c_cpuarray may not be read with enabled local interrupts -
 * it's changed with a smp_call_function().
 *
 * SMP synchronization:
 *  constructors and destructors are called without any locking.
 *  Several members in struct kmem_cache and struct slab never change, they
 *      are accessed without any locking.
 *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
 *      and local interrupts are disabled so slab code is preempt-safe.
 *  The non-constant members are protected with a per-cache irq spinlock.
 *
 * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
 * in 2000 - many ideas in the current implementation are derived from
 * his patch.
 *
 * Further notes from the original documentation:
 *
 * 11 April '97.  Started multi-threading - markhe
 *      The global cache-chain is protected by the mutex 'cache_chain_mutex'.
 *      The sem is only needed when accessing/extending the cache-chain, which
 *      can never happen inside an interrupt (kmem_cache_create(),
 *      kmem_cache_shrink() and kmem_cache_reap()).
 *
 *      At present, each engine can be growing a cache.  This should be blocked.
 *
 * 15 March 2005. NUMA slab allocator.
 *      Shai Fultheim <shai@scalex86.org>.
 *      Shobhit Dayal <shobhit@calsoftinc.com>
 *      Alok N Kataria <alokk@calsoftinc.com>
 *      Christoph Lameter <christoph@lameter.com>
 *
 *      Modified the slab allocator to be node aware on NUMA systems.
 *      Each node has its own list of partial, free and full slabs.
 *      All object allocations for a node occur from node specific slab lists.
 */

#include        <linux/slab.h>
#include        <linux/mm.h>
#include        <linux/poison.h>
#include        <linux/swap.h>
#include        <linux/cache.h>
#include        <linux/interrupt.h>
#include        <linux/init.h>
#include        <linux/compiler.h>
#include        <linux/cpuset.h>
#include        <linux/proc_fs.h>
#include        <linux/seq_file.h>
#include        <linux/notifier.h>
#include        <linux/kallsyms.h>
#include        <linux/cpu.h>
#include        <linux/sysctl.h>
#include        <linux/module.h>
#include        <trace/kmemtrace.h>
#include        <linux/rcupdate.h>
#include        <linux/string.h>
#include        <linux/uaccess.h>
#include        <linux/nodemask.h>
#include        <linux/mempolicy.h>
#include        <linux/mutex.h>
#include        <linux/fault-inject.h>
#include        <linux/rtmutex.h>
#include        <linux/reciprocal_div.h>
#include        <linux/debugobjects.h>

#include        <asm/cacheflush.h>
#include        <asm/tlbflush.h>
#include        <asm/page.h>

/*
 * DEBUG        - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
 *                0 for faster, smaller code (especially in the critical paths).
 *
 * STATS        - 1 to collect stats for /proc/slabinfo.
 *                0 for faster, smaller code (especially in the critical paths).
 *
 * FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
 */

#ifdef CONFIG_DEBUG_SLAB
#define DEBUG           1
#define STATS           1
#define FORCED_DEBUG    1
#else
#define DEBUG           0
#define STATS           0
#define FORCED_DEBUG    0
#endif

/* Shouldn't this be in a header file somewhere? */
#define BYTES_PER_WORD          sizeof(void *)
#define REDZONE_ALIGN           max(BYTES_PER_WORD, __alignof__(unsigned long long))

#ifndef ARCH_KMALLOC_MINALIGN
/*
 * Enforce a minimum alignment for the kmalloc caches.
 * Usually, the kmalloc caches are cache_line_size() aligned, except when
 * DEBUG and FORCED_DEBUG are enabled, then they are BYTES_PER_WORD aligned.
 * Some archs want to perform DMA into kmalloc caches and need a guaranteed
 * alignment larger than the alignment of a 64-bit integer.
 * ARCH_KMALLOC_MINALIGN allows that.
 * Note that increasing this value may disable some debug features.
 */
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
#endif

#ifndef ARCH_SLAB_MINALIGN
/*
 * Enforce a minimum alignment for all caches.
 * Intended for archs that get misalignment faults even for BYTES_PER_WORD
 * aligned buffers. Includes ARCH_KMALLOC_MINALIGN.
 * If possible: Do not enable this flag for CONFIG_DEBUG_SLAB, it disables
 * some debug features.
 */
#define ARCH_SLAB_MINALIGN 0
#endif

#ifndef ARCH_KMALLOC_FLAGS
#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
#endif

/* Legal flag mask for kmem_cache_create(). */
#if DEBUG
# define CREATE_MASK    (SLAB_RED_ZONE | \
                         SLAB_POISON | SLAB_HWCACHE_ALIGN | \
                         SLAB_CACHE_DMA | \
                         SLAB_STORE_USER | \
                         SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                         SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \
                         SLAB_DEBUG_OBJECTS)
#else
# define CREATE_MASK    (SLAB_HWCACHE_ALIGN | \
                         SLAB_CACHE_DMA | \
                         SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                         SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \
                         SLAB_DEBUG_OBJECTS)
#endif

/*
 * kmem_bufctl_t:
 *
 * Bufctl's are used for linking objs within a slab
 * linked offsets.
 *
 * This implementation relies on "struct page" for locating the cache &
 * slab an object belongs to.
 * This allows the bufctl structure to be small (one int), but limits
 * the number of objects a slab (not a cache) can contain when off-slab
 * bufctls are used. The limit is the size of the largest general cache
 * that does not use off-slab slabs.
 * For 32bit archs with 4 kB pages, is this 56.
 * This is not serious, as it is only for large objects, when it is unwise
 * to have too many per slab.
 * Note: This limit can be raised by introducing a general cache whose size
 * is less than 512 (PAGE_SIZE<<3), but greater than 256.
 */

typedef unsigned int kmem_bufctl_t;
#define BUFCTL_END      (((kmem_bufctl_t)(~0U))-0)
#define BUFCTL_FREE     (((kmem_bufctl_t)(~0U))-1)
#define BUFCTL_ACTIVE   (((kmem_bufctl_t)(~0U))-2)
#define SLAB_LIMIT      (((kmem_bufctl_t)(~0U))-3)

/*
 * struct slab
 *
 * Manages the objs in a slab. Placed either at the beginning of mem allocated
 * for a slab, or allocated from an general cache.
 * Slabs are chained into three list: fully used, partial, fully free slabs.
 */
struct slab {
        struct list_head list;
        unsigned long colouroff;
        void *s_mem;            /* including colour offset */
        unsigned int inuse;     /* num of objs active in slab */
        kmem_bufctl_t free;
        unsigned short nodeid;
};

/*
 * struct slab_rcu
 *
 * slab_destroy on a SLAB_DESTROY_BY_RCU cache uses this structure to
 * arrange for kmem_freepages to be called via RCU.  This is useful if
 * we need to approach a kernel structure obliquely, from its address
 * obtained without the usual locking.  We can lock the structure to
 * stabilize it and check it's still at the given address, only if we
 * can be sure that the memory has not been meanwhile reused for some
 * other kind of object (which our subsystem's lock might corrupt).
 *
 * rcu_read_lock before reading the address, then rcu_read_unlock after
 * taking the spinlock within the structure expected at that address.
 *
 * We assume struct slab_rcu can overlay struct slab when destroying.
 */
struct slab_rcu {
        struct rcu_head head;
        struct kmem_cache *cachep;
        void *addr;
};

/*
 * struct array_cache
 *
 * Purpose:
 * - LIFO ordering, to hand out cache-warm objects from _alloc
 * - reduce the number of linked list operations
 * - reduce spinlock operations
 *
 * The limit is stored in the per-cpu structure to reduce the data cache
 * footprint.
 *
 */
struct array_cache {
        unsigned int avail;
        unsigned int limit;
        unsigned int batchcount;
        unsigned int touched;
        spinlock_t lock;
        void *entry[];  /*
                         * Must have this definition in here for the proper
                         * alignment of array_cache. Also simplifies accessing
                         * the entries.
                         */
};

/*
 * bootstrap: The caches do not work without cpuarrays anymore, but the
 * cpuarrays are allocated from the generic caches...
 */
#define BOOT_CPUCACHE_ENTRIES   1
struct arraycache_init {
        struct array_cache cache;
        void *entries[BOOT_CPUCACHE_ENTRIES];
};

/*
 * The slab lists for all objects.
 */
struct kmem_list3 {
        struct list_head slabs_partial; /* partial list first, better asm code */
        struct list_head slabs_full;
        struct list_head slabs_free;
        unsigned long free_objects;
        unsigned int free_limit;
        unsigned int colour_next;       /* Per-node cache coloring */
        spinlock_t list_lock;
        struct array_cache *shared;     /* shared per node */
        struct array_cache **alien;     /* on other nodes */
        unsigned long next_reap;        /* updated without locking */
        int free_touched;               /* updated without locking */
};

/*
 * Need this for bootstrapping a per node allocator.
 */
#define NUM_INIT_LISTS (3 * MAX_NUMNODES)
struct kmem_list3 __initdata initkmem_list3[NUM_INIT_LISTS];
#define CACHE_CACHE 0
#define SIZE_AC MAX_NUMNODES
#define SIZE_L3 (2 * MAX_NUMNODES)

static int drain_freelist(struct kmem_cache *cache,
                        struct kmem_list3 *l3, int tofree);
static void free_block(struct kmem_cache *cachep, void **objpp, int len,
                        int node);
static int enable_cpucache(struct kmem_cache *cachep);
static void cache_reap(struct work_struct *unused);

/*
 * This function must be completely optimized away if a constant is passed to
 * it.  Mostly the same as what is in linux/slab.h except it returns an index.
 */
static __always_inline int index_of(const size_t size)
{
        extern void __bad_size(void);

        if (__builtin_constant_p(size)) {
                int i = 0;

#define CACHE(x) \
        if (size <=x) \
                return i; \
        else \
                i++;
#include <linux/kmalloc_sizes.h>
#undef CACHE
                __bad_size();
        } else
                __bad_size();
        return 0;
}

static int slab_early_init = 1;

#define INDEX_AC index_of(sizeof(struct arraycache_init))
#define INDEX_L3 index_of(sizeof(struct kmem_list3))

static void kmem_list3_init(struct kmem_list3 *parent)
{
        INIT_LIST_HEAD(&parent->slabs_full);
        INIT_LIST_HEAD(&parent->slabs_partial);
        INIT_LIST_HEAD(&parent->slabs_free);
        parent->shared = NULL;
        parent->alien = NULL;
        parent->colour_next = 0;
        spin_lock_init(&parent->list_lock);
        parent->free_objects = 0;
        parent->free_touched = 0;
}

#define MAKE_LIST(cachep, listp, slab, nodeid)                          \
        do {                                                            \
                INIT_LIST_HEAD(listp);                                  \
                list_splice(&(cachep->nodelists[nodeid]->slab), listp); \
        } while (0)

#define MAKE_ALL_LISTS(cachep, ptr, nodeid)                             \
        do {                                                            \
        MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);  \
        MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
        MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);  \
        } while (0)

/*
 * struct kmem_cache
 *
 * manages a cache.
 */

struct kmem_cache {
/* 1) per-cpu data, touched during every alloc/free */
        struct array_cache *array[NR_CPUS];
/* 2) Cache tunables. Protected by cache_chain_mutex */
        unsigned int batchcount;
        unsigned int limit;
        unsigned int shared;

        unsigned int buffer_size;
        u32 reciprocal_buffer_size;
/* 3) touched by every alloc & free from the backend */

        unsigned int flags;             /* constant flags */
        unsigned int num;               /* # of objs per slab */

/* 4) cache_grow/shrink */
        /* order of pgs per slab (2^n) */
        unsigned int gfporder;

        /* force GFP flags, e.g. GFP_DMA */
        gfp_t gfpflags;

        size_t colour;                  /* cache colouring range */
        unsigned int colour_off;        /* colour offset */
        struct kmem_cache *slabp_cache;
        unsigned int slab_size;
        unsigned int dflags;            /* dynamic flags */

        /* constructor func */
        void (*ctor)(void *obj);

/* 5) cache creation/removal */
        const char *name;
        struct list_head next;

/* 6) statistics */
#if STATS
        unsigned long num_active;
        unsigned long num_allocations;
        unsigned long high_mark;
        unsigned long grown;
        unsigned long reaped;
        unsigned long errors;
        unsigned long max_freeable;
        unsigned long node_allocs;
        unsigned long node_frees;
        unsigned long node_overflow;
        atomic_t allochit;
        atomic_t allocmiss;
        atomic_t freehit;
        atomic_t freemiss;
#endif
#if DEBUG
        /*
         * If debugging is enabled, then the allocator can add additional
         * fields and/or padding to every object. buffer_size contains the total
         * object size including these internal fields, the following two
         * variables contain the offset to the user object and its size.
         */
        int obj_offset;
        int obj_size;
#endif
        /*
         * We put nodelists[] at the end of kmem_cache, because we want to size
         * this array to nr_node_ids slots instead of MAX_NUMNODES
         * (see kmem_cache_init())
         * We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
         * is statically defined, so we reserve the max number of nodes.
         */
        struct kmem_list3 *nodelists[MAX_NUMNODES];
        /*
         * Do not add fields after nodelists[]
         */
};

#define CFLGS_OFF_SLAB          (0x80000000UL)
#define OFF_SLAB(x)     ((x)->flags & CFLGS_OFF_SLAB)

#define BATCHREFILL_LIMIT       16
/*
 * Optimization question: fewer reaps means less probability for unnessary
 * cpucache drain/refill cycles.
 *
 * OTOH the cpuarrays can contain lots of objects,
 * which could lock up otherwise freeable slabs.
 */
#define REAPTIMEOUT_CPUC        (2*HZ)
#define REAPTIMEOUT_LIST3       (4*HZ)

#if STATS
#define STATS_INC_ACTIVE(x)     ((x)->num_active++)
#define STATS_DEC_ACTIVE(x)     ((x)->num_active--)
#define STATS_INC_ALLOCED(x)    ((x)->num_allocations++)
#define STATS_INC_GROWN(x)      ((x)->grown++)
#define STATS_ADD_REAPED(x,y)   ((x)->reaped += (y))
#define STATS_SET_HIGH(x)                                               \
        do {                                                            \
                if ((x)->num_active > (x)->high_mark)                   \
                        (x)->high_mark = (x)->num_active;               \
        } while (0)
#define STATS_INC_ERR(x)        ((x)->errors++)
#define STATS_INC_NODEALLOCS(x) ((x)->node_allocs++)
#define STATS_INC_NODEFREES(x)  ((x)->node_frees++)
#define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
#define STATS_SET_FREEABLE(x, i)                                        \
        do {                                                            \
                if ((x)->max_freeable < i)                              \
                        (x)->max_freeable = i;                          \
        } while (0)
#define STATS_INC_ALLOCHIT(x)   atomic_inc(&(x)->allochit)
#define STATS_INC_ALLOCMISS(x)  atomic_inc(&(x)->allocmiss)
#define STATS_INC_FREEHIT(x)    atomic_inc(&(x)->freehit)
#define STATS_INC_FREEMISS(x)   atomic_inc(&(x)->freemiss)
#else
#define STATS_INC_ACTIVE(x)     do { } while (0)
#define STATS_DEC_ACTIVE(x)     do { } while (0)
#define STATS_INC_ALLOCED(x)    do { } while (0)
#define STATS_INC_GROWN(x)      do { } while (0)
#define STATS_ADD_REAPED(x,y)   do { } while (0)
#define STATS_SET_HIGH(x)       do { } while (0)
#define STATS_INC_ERR(x)        do { } while (0)
#define STATS_INC_NODEALLOCS(x) do { } while (0)
#define STATS_INC_NODEFREES(x)  do { } while (0)
#define STATS_INC_ACOVERFLOW(x)   do { } while (0)
#define STATS_SET_FREEABLE(x, i) do { } while (0)
#define STATS_INC_ALLOCHIT(x)   do { } while (0)
#define STATS_INC_ALLOCMISS(x)  do { } while (0)
#define STATS_INC_FREEHIT(x)    do { } while (0)
#define STATS_INC_FREEMISS(x)   do { } while (0)
#endif

#if DEBUG

/*
 * memory layout of objects:
 * 0            : objp
 * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
 *              the end of an object is aligned with the end of the real
 *              allocation. Catches writes behind the end of the allocation.
 * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
 *              redzone word.
 * cachep->obj_offset: The real object.
 * cachep->buffer_size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
 * cachep->buffer_size - 1* BYTES_PER_WORD: last caller address
 *                                      [BYTES_PER_WORD long]
 */
static int obj_offset(struct kmem_cache *cachep)
{
        return cachep->obj_offset;
}

static int obj_size(struct kmem_cache *cachep)
{
        return cachep->obj_size;
}

static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
{
        BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
        return (unsigned long long*) (objp + obj_offset(cachep) -
                                      sizeof(unsigned long long));
}

static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
{
        BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
        if (cachep->flags & SLAB_STORE_USER)
                return (unsigned long long *)(objp + cachep->buffer_size -
                                              sizeof(unsigned long long) -
                                              REDZONE_ALIGN);
        return (unsigned long long *) (objp + cachep->buffer_size -
                                       sizeof(unsigned long long));
}

static void **dbg_userword(struct kmem_cache *cachep, void *objp)
{
        BUG_ON(!(cachep->flags & SLAB_STORE_USER));
        return (void **)(objp + cachep->buffer_size - BYTES_PER_WORD);
}

#else

#define obj_offset(x)                   0
#define obj_size(cachep)                (cachep->buffer_size)
#define dbg_redzone1(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
#define dbg_redzone2(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
#define dbg_userword(cachep, objp)      ({BUG(); (void **)NULL;})

#endif

#ifdef CONFIG_KMEMTRACE
size_t slab_buffer_size(struct kmem_cache *cachep)
{
        return cachep->buffer_size;
}
EXPORT_SYMBOL(slab_buffer_size);
#endif

/*
 * Do not go above this order unless 0 objects fit into the slab.
 */
#define BREAK_GFP_ORDER_HI      1
#define BREAK_GFP_ORDER_LO      0
static int slab_break_gfp_order = BREAK_GFP_ORDER_LO;

/*
 * Functions for storing/retrieving the cachep and or slab from the page
 * allocator.  These are used to find the slab an obj belongs to.  With kfree(),
 * these are used to find the cache which an obj belongs to.
 */
static inline void page_set_cache(struct page *page, struct kmem_cache *cache)
{
        page->lru.next = (struct list_head *)cache;
}

static inline struct kmem_cache *page_get_cache(struct page *page)
{
        page = compound_head(page);
        BUG_ON(!PageSlab(page));
        return (struct kmem_cache *)page->lru.next;
}

static inline void page_set_slab(struct page *page, struct slab *slab)
{
        page->lru.prev = (struct list_head *)slab;
}

static inline struct slab *page_get_slab(struct page *page)
{
        BUG_ON(!PageSlab(page));
        return (struct slab *)page->lru.prev;
}

static inline struct kmem_cache *virt_to_cache(const void *obj)
{
        struct page *page = virt_to_head_page(obj);
        return page_get_cache(page);
}

static inline struct slab *virt_to_slab(const void *obj)
{
        struct page *page = virt_to_head_page(obj);
        return page_get_slab(page);
}

static inline void *index_to_obj(struct kmem_cache *cache, struct slab *slab,
                                 unsigned int idx)
{
        return slab->s_mem + cache->buffer_size * idx;
}

/*
 * We want to avoid an expensive divide : (offset / cache->buffer_size)
 *   Using the fact that buffer_size is a constant for a particular cache,
 *   we can replace (offset / cache->buffer_size) by
 *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
 */
static inline unsigned int obj_to_index(const struct kmem_cache *cache,
                                        const struct slab *slab, void *obj)
{
        u32 offset = (obj - slab->s_mem);
        return reciprocal_divide(offset, cache->reciprocal_buffer_size);
}

/*
 * These are the default caches for kmalloc. Custom caches can have other sizes.
 */
struct cache_sizes malloc_sizes[] = {
#define CACHE(x) { .cs_size = (x) },
#include <linux/kmalloc_sizes.h>
        CACHE(ULONG_MAX)
#undef CACHE
};
EXPORT_SYMBOL(malloc_sizes);

/* Must match cache_sizes above. Out of line to keep cache footprint low. */
struct cache_names {
        char *name;
        char *name_dma;
};

static struct cache_names __initdata cache_names[] = {
#define CACHE(x) { .name = "size-" #x, .name_dma = "size-" #x "(DMA)" },
#include <linux/kmalloc_sizes.h>
        {NULL,}
#undef CACHE
};

static struct arraycache_init initarray_cache __initdata =
    { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
static struct arraycache_init initarray_generic =
    { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };

/* internal cache of cache description objs */
static struct kmem_cache cache_cache = {
        .batchcount = 1,
        .limit = BOOT_CPUCACHE_ENTRIES,
        .shared = 1,
        .buffer_size = sizeof(struct kmem_cache),
        .name = "kmem_cache",
};

#define BAD_ALIEN_MAGIC 0x01020304ul

#ifdef CONFIG_LOCKDEP

/*
 * Slab sometimes uses the kmalloc slabs to store the slab headers
 * for other slabs "off slab".
 * The locking for this is tricky in that it nests within the locks
 * of all other slabs in a few places; to deal with this special
 * locking we put on-slab caches into a separate lock-class.
 *
 * We set lock class for alien array caches which are up during init.
 * The lock annotation will be lost if all cpus of a node goes down and
 * then comes back up during hotplug
 */
static struct lock_class_key on_slab_l3_key;
static struct lock_class_key on_slab_alc_key;

static inline void init_lock_keys(void)

{
        int q;
        struct cache_sizes *s = malloc_sizes;

        while (s->cs_size != ULONG_MAX) {
                for_each_node(q) {
                        struct array_cache **alc;
                        int r;
                        struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];
                        if (!l3 || OFF_SLAB(s->cs_cachep))
                                continue;
                        lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
                        alc = l3->alien;
                        /*
                         * FIXME: This check for BAD_ALIEN_MAGIC
                         * should go away when common slab code is taught to
                         * work even without alien caches.
                         * Currently, non NUMA code returns BAD_ALIEN_MAGIC
                         * for alloc_alien_cache,
                         */
                        if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
                                continue;
                        for_each_node(r) {
                                if (alc[r])
                                        lockdep_set_class(&alc[r]->lock,
                                             &on_slab_alc_key);
                        }
                }
                s++;
        }
}
#else
static inline void init_lock_keys(void)
{
}
#endif

/*
 * Guard access to the cache-chain.
 */
static DEFINE_MUTEX(cache_chain_mutex);
static struct list_head cache_chain;

/*
 * chicken and egg problem: delay the per-cpu array allocation
 * until the general caches are up.
 */
static enum {
        NONE,
        PARTIAL_AC,
        PARTIAL_L3,
        FULL
} g_cpucache_up;

/*
 * used by boot code to determine if it can use slab based allocator
 */
int slab_is_available(void)
{
        return g_cpucache_up == FULL;
}

static DEFINE_PER_CPU(struct delayed_work, reap_work);

static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
{
        return cachep->array[smp_processor_id()];
}

static inline struct kmem_cache *__find_general_cachep(size_t size,
                                                        gfp_t gfpflags)
{
        struct cache_sizes *csizep = malloc_sizes;

#if DEBUG
        /* This happens if someone tries to call
         * kmem_cache_create(), or __kmalloc(), before
         * the generic caches are initialized.
         */
        BUG_ON(malloc_sizes[INDEX_AC].cs_cachep == NULL);
#endif
        if (!size)
                return ZERO_SIZE_PTR;

        while (size > csizep->cs_size)
                csizep++;

        /*
         * Really subtle: The last entry with cs->cs_size==ULONG_MAX
         * has cs_{dma,}cachep==NULL. Thus no special case
         * for large kmalloc calls required.
         */
#ifdef CONFIG_ZONE_DMA
        if (unlikely(gfpflags & GFP_DMA))
                return csizep->cs_dmacachep;
#endif
        return csizep->cs_cachep;
}

static struct kmem_cache *kmem_find_general_cachep(size_t size, gfp_t gfpflags)
{
        return __find_general_cachep(size, gfpflags);
}

static size_t slab_mgmt_size(size_t nr_objs, size_t align)
{
        return ALIGN(sizeof(struct slab)+nr_objs*sizeof(kmem_bufctl_t), align);
}

/*
 * Calculate the number of objects and left-over bytes for a given buffer size.
 */
static void cache_estimate(unsigned long gfporder, size_t buffer_size,
                           size_t align, int flags, size_t *left_over,
                           unsigned int *num)
{
        int nr_objs;
        size_t mgmt_size;
        size_t slab_size = PAGE_SIZE << gfporder;

        /*
         * The slab management structure can be either off the slab or
         * on it. For the latter case, the memory allocated for a
         * slab is used for:
         *
         * - The struct slab
         * - One kmem_bufctl_t for each object
         * - Padding to respect alignment of @align
         * - @buffer_size bytes for each object
         *
         * If the slab management structure is off the slab, then the
         * alignment will already be calculated into the size. Because
         * the slabs are all pages aligned, the objects will be at the
         * correct alignment when allocated.
         */
        if (flags & CFLGS_OFF_SLAB) {
                mgmt_size = 0;
                nr_objs = slab_size / buffer_size;

                if (nr_objs > SLAB_LIMIT)
                        nr_objs = SLAB_LIMIT;
        } else {
                /*
                 * Ignore padding for the initial guess. The padding
                 * is at most @align-1 bytes, and @buffer_size is at
                 * least @align. In the worst case, this result will
                 * be one greater than the number of objects that fit
                 * into the memory allocation when taking the padding
                 * into account.
                 */
                nr_objs = (slab_size - sizeof(struct slab)) /
                          (buffer_size + sizeof(kmem_bufctl_t));

                /*
                 * This calculated number will be either the right
                 * amount, or one greater than what we want.
                 */
                if (slab_mgmt_size(nr_objs, align) + nr_objs*buffer_size
                       > slab_size)
                        nr_objs--;

                if (nr_objs > SLAB_LIMIT)
                        nr_objs = SLAB_LIMIT;

                mgmt_size = slab_mgmt_size(nr_objs, align);
        }
        *num = nr_objs;
        *left_over = slab_size - nr_objs*buffer_size - mgmt_size;
}

#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)

static void __slab_error(const char *function, struct kmem_cache *cachep,
                        char *msg)
{
        printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
               function, cachep->name, msg);
        dump_stack();
}

/*
 * By default on NUMA we use alien caches to stage the freeing of
 * objects allocated from other nodes. This causes massive memory
 * inefficiencies when using fake NUMA setup to split memory into a
 * large number of small nodes, so it can be disabled on the command
 * line
  */

static int use_alien_caches __read_mostly = 1;
static int numa_platform __read_mostly = 1;
static int __init noaliencache_setup(char *s)
{
        use_alien_caches = 0;
        return 1;
}
__setup("noaliencache", noaliencache_setup);

#ifdef CONFIG_NUMA
/*
 * Special reaping functions for NUMA systems called from cache_reap().
 * These take care of doing round robin flushing of alien caches (containing
 * objects freed on different nodes from which they were allocated) and the
 * flushing of remote pcps by calling drain_node_pages.
 */
static DEFINE_PER_CPU(unsigned long, reap_node);

static void init_reap_node(int cpu)
{
        int node;

        node = next_node(cpu_to_node(cpu), node_online_map);
        if (node == MAX_NUMNODES)
                node = first_node(node_online_map);

        per_cpu(reap_node, cpu) = node;
}

static void next_reap_node(void)
{
        int node = __get_cpu_var(reap_node);

        node = next_node(node, node_online_map);
        if (unlikely(node >= MAX_NUMNODES))
                node = first_node(node_online_map);
        __get_cpu_var(reap_node) = node;
}

#else
#define init_reap_node(cpu) do { } while (0)
#define next_reap_node(void) do { } while (0)
#endif

/*
 * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
 * via the workqueue/eventd.
 * Add the CPU number into the expiration time to minimize the possibility of
 * the CPUs getting into lockstep and contending for the global cache chain
 * lock.
 */
static void __cpuinit start_cpu_timer(int cpu)
{
        struct delayed_work *reap_work = &per_cpu(reap_work, cpu);

        /*
         * When this gets called from do_initcalls via cpucache_init(),
         * init_workqueues() has already run, so keventd will be setup
         * at that time.
         */
        if (keventd_up() && reap_work->work.func == NULL) {
                init_reap_node(cpu);
                INIT_DELAYED_WORK(reap_work, cache_reap);
                schedule_delayed_work_on(cpu, reap_work,
                                        __round_jiffies_relative(HZ, cpu));
        }
}

static struct array_cache *alloc_arraycache(int node, int entries,
                                            int batchcount)
{
        int memsize = sizeof(void *) * entries + sizeof(struct array_cache);
        struct array_cache *nc = NULL;

        nc = kmalloc_node(memsize, GFP_KERNEL, node);
        if (nc) {
                nc->avail = 0;
                nc->limit = entries;
                nc->batchcount = batchcount;
                nc->touched = 0;
                spin_lock_init(&nc->lock);
        }
        return nc;
}

/*
 * Transfer objects in one arraycache to another.
 * Locking must be handled by the caller.
 *
 * Return the number of entries transferred.
 */
static int transfer_objects(struct array_cache *to,
                struct array_cache *from, unsigned int max)
{
        /* Figure out how many entries to transfer */
        int nr = min(min(from->avail, max), to->limit - to->avail);

        if (!nr)
                return 0;

        memcpy(to->entry + to->avail, from->entry + from->avail -nr,
                        sizeof(void *) *nr);

        from->avail -= nr;
        to->avail += nr;
        to->touched = 1;
        return nr;
}

#ifndef CONFIG_NUMA

#define drain_alien_cache(cachep, alien) do { } while (0)
#define reap_alien(cachep, l3) do { } while (0)

static inline struct array_cache **alloc_alien_cache(int node, int limit)
{
        return (struct array_cache **)BAD_ALIEN_MAGIC;
}

static inline void free_alien_cache(struct array_cache **ac_ptr)
{
}

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
        return 0;
}

static inline void *alternate_node_alloc(struct kmem_cache *cachep,
                gfp_t flags)
{
        return NULL;
}

static inline void *____cache_alloc_node(struct kmem_cache *cachep,
                 gfp_t flags, int nodeid)
{
        return NULL;
}

#else   /* CONFIG_NUMA */

static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
static void *alternate_node_alloc(struct kmem_cache *, gfp_t);

static struct array_cache **alloc_alien_cache(int node, int limit)
{
        struct array_cache **ac_ptr;
        int memsize = sizeof(void *) * nr_node_ids;
        int i;

        if (limit > 1)
                limit = 12;
        ac_ptr = kmalloc_node(memsize, GFP_KERNEL, node);
        if (ac_ptr) {
                for_each_node(i) {
                        if (i == node || !node_online(i)) {
                                ac_ptr[i] = NULL;
                                continue;
                        }
                        ac_ptr[i] = alloc_arraycache(node, limit, 0xbaadf00d);
                        if (!ac_ptr[i]) {
                                for (i--; i >= 0; i--)
                                        kfree(ac_ptr[i]);
                                kfree(ac_ptr);
                                return NULL;
                        }
                }
        }
        return ac_ptr;
}

static void free_alien_cache(struct array_cache **ac_ptr)
{
        int i;

        if (!ac_ptr)
                return;
        for_each_node(i)
            kfree(ac_ptr[i]);
        kfree(ac_ptr);
}

static void __drain_alien_cache(struct kmem_cache *cachep,
                                struct array_cache *ac, int node)
{
        struct kmem_list3 *rl3 = cachep->nodelists[node];

        if (ac->avail) {
                spin_lock(&rl3->list_lock);
                /*
                 * Stuff objects into the remote nodes shared array first.
                 * That way we could avoid the overhead of putting the objects
                 * into the free lists and getting them back later.
                 */
                if (rl3->shared)
                        transfer_objects(rl3->shared, ac, ac->limit);

                free_block(cachep, ac->entry, ac->avail, node);
                ac->avail = 0;
                spin_unlock(&rl3->list_lock);
        }
}

/*
 * Called from cache_reap() to regularly drain alien caches round robin.
 */
static void reap_alien(struct kmem_cache *cachep, struct kmem_list3 *l3)
{
        int node = __get_cpu_var(reap_node);

        if (l3->alien) {
                struct array_cache *ac = l3->alien[node];

                if (ac && ac->avail && spin_trylock_irq(&ac->lock)) {
                        __drain_alien_cache(cachep, ac, node);
                        spin_unlock_irq(&ac->lock);
                }
        }
}

static void drain_alien_cache(struct kmem_cache *cachep,
                                struct array_cache **alien)
{
        int i = 0;
        struct array_cache *ac;
        unsigned long flags;

        for_each_online_node(i) {
                ac = alien[i];
                if (ac) {
                        spin_lock_irqsave(&ac->lock, flags);
                        __drain_alien_cache(cachep, ac, i);
                        spin_unlock_irqrestore(&ac->lock, flags);
                }
        }
}

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
        struct slab *slabp = virt_to_slab(objp);
        int nodeid = slabp->nodeid;
        struct kmem_list3 *l3;
        struct array_cache *alien = NULL;
        int node;

        node = numa_node_id();

        /*
         * Make sure we are not freeing a object from another node to the array
         * cache on this cpu.
         */
        if (likely(slabp->nodeid == node))
                return 0;

        l3 = cachep->nodelists[node];
        STATS_INC_NODEFREES(cachep);
        if (l3->alien && l3->alien[nodeid]) {
                alien = l3->alien[nodeid];
                spin_lock(&alien->lock);
                if (unlikely(alien->avail == alien->limit)) {
                        STATS_INC_ACOVERFLOW(cachep);
                        __drain_alien_cache(cachep, alien, nodeid);
                }
                alien->entry[alien->avail++] = objp;
                spin_unlock(&alien->lock);
        } else {
                spin_lock(&(cachep->nodelists[nodeid])->list_lock);
                free_block(cachep, &objp, 1, nodeid);
                spin_unlock(&(cachep->nodelists[nodeid])->list_lock);
        }
        return 1;
}
#endif

static void __cpuinit cpuup_canceled(long cpu)
{
        struct kmem_cache *cachep;
        struct kmem_list3 *l3 = NULL;
        int node = cpu_to_node(cpu);
        const struct cpumask *mask = cpumask_of_node(node);

        list_for_each_entry(cachep, &cache_chain, next) {
                struct array_cache *nc;
                struct array_cache *shared;
                struct array_cache **alien;

                /* cpu is dead; no one can alloc from it. */
                nc = cachep->array[cpu];
                cachep->array[cpu] = NULL;
                l3 = cachep->nodelists[node];

                if (!l3)
                        goto free_array_cache;

                spin_lock_irq(&l3->list_lock);

                /* Free limit for this kmem_list3 */
                l3->free_limit -= cachep->batchcount;
                if (nc)
                        free_block(cachep, nc->entry, nc->avail, node);

                if (!cpus_empty(*mask)) {
                        spin_unlock_irq(&l3->list_lock);
                        goto free_array_cache;
                }

                shared = l3->shared;
                if (shared) {
                        free_block(cachep, shared->entry,
                                   shared->avail, node);
                        l3->shared = NULL;
                }

                alien = l3->alien;
                l3->alien = NULL;

                spin_unlock_irq(&l3->list_lock);

                kfree(shared);
                if (alien) {
                        drain_alien_cache(cachep, alien);
                        free_alien_cache(alien);
                }
free_array_cache:
                kfree(nc);
        }
        /*
         * In the previous loop, all the objects were freed to
         * the respective cache's slabs,  now we can go ahead and
         * shrink each nodelist to its limit.
         */
        list_for_each_entry(cachep, &cache_chain, next) {
                l3 = cachep->nodelists[node];
                if (!l3)
                        continue;
                drain_freelist(cachep, l3, l3->free_objects);
        }
}

static int __cpuinit cpuup_prepare(long cpu)
{
        struct kmem_cache *cachep;
        struct kmem_list3 *l3 = NULL;
        int node = cpu_to_node(cpu);
        const int memsize = sizeof(struct kmem_list3);

        /*
         * We need to do this right in the beginning since
         * alloc_arraycache's are going to use this list.
         * kmalloc_node allows us to add the slab to the right
         * kmem_list3 and not this cpu's kmem_list3
         */

        list_for_each_entry(cachep, &cache_chain, next) {
                /*
                 * Set up the size64 kmemlist for cpu before we can
                 * begin anything. Make sure some other cpu on this
                 * node has not already allocated this
                 */
                if (!cachep->nodelists[node]) {
                        l3 = kmalloc_node(memsize, GFP_KERNEL, node);
                        if (!l3)
                                goto bad;
                        kmem_list3_init(l3);
                        l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
                            ((unsigned long)cachep) % REAPTIMEOUT_LIST3;

                        /*
                         * The l3s don't come and go as CPUs come and
                         * go.  cache_chain_mutex is sufficient
                         * protection here.
                         */
                        cachep->nodelists[node] = l3;
                }

                spin_lock_irq(&cachep->nodelists[node]->list_lock);
                cachep->nodelists[node]->free_limit =
                        (1 + nr_cpus_node(node)) *
                        cachep->batchcount + cachep->num;
                spin_unlock_irq(&cachep->nodelists[node]->list_lock);
        }

        /*
         * Now we can go ahead with allocating the shared arrays and
         * array caches
         */
        list_for_each_entry(cachep, &cache_chain, next) {
                struct array_cache *nc;
                struct array_cache *shared = NULL;
                struct array_cache **alien = NULL;

                nc = alloc_arraycache(node, cachep->limit,
                                        cachep->batchcount);
                if (!nc)
                        goto bad;
                if (cachep->shared) {
                        shared = alloc_arraycache(node,
                                cachep->shared * cachep->batchcount,
                                0xbaadf00d);
                        if (!shared) {
                                kfree(nc);
                                goto bad;
                        }
                }
                if (use_alien_caches) {
                        alien = alloc_alien_cache(node, cachep->limit);
                        if (!alien) {
                                kfree(shared);
                                kfree(nc);
                                goto bad;
                        }
                }
                cachep->array[cpu] = nc;
                l3 = cachep->nodelists[node];
                BUG_ON(!l3);

                spin_lock_irq(&l3->list_lock);
                if (!l3->shared) {
                        /*
                         * We are serialised from CPU_DEAD or
                         * CPU_UP_CANCELLED by the cpucontrol lock
                         */
                        l3->shared = shared;
                        shared = NULL;
                }
#ifdef CONFIG_NUMA
                if (!l3->alien) {
                        l3->alien = alien;
                        alien = NULL;
                }
#endif
                spin_unlock_irq(&l3->list_lock);
                kfree(shared);
                free_alien_cache(alien);
        }
        return 0;
bad:
        cpuup_canceled(cpu);
        return -ENOMEM;
}

static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                                    unsigned long action, void *hcpu)
{
        long cpu = (long)hcpu;
        int err = 0;

        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
                mutex_lock(&cache_chain_mutex);
                err = cpuup_prepare(cpu);
                mutex_unlock(&cache_chain_mutex);
                break;
        case CPU_ONLINE:
        case CPU_ONLINE_FROZEN:
                start_cpu_timer(cpu);
                break;
#ifdef CONFIG_HOTPLUG_CPU
        case CPU_DOWN_PREPARE:
        case CPU_DOWN_PREPARE_FROZEN:
                /*
                 * Shutdown cache reaper. Note that the cache_chain_mutex is
                 * held so that if cache_reap() is invoked it cannot do
                 * anything expensive but will only modify reap_work
                 * and reschedule the timer.
                */
                cancel_rearming_delayed_work(&per_cpu(reap_work, cpu));
                /* Now the cache_reaper is guaranteed to be not running. */
                per_cpu(reap_work, cpu).work.func = NULL;
                break;
        case CPU_DOWN_FAILED:
        case CPU_DOWN_FAILED_FROZEN:
                start_cpu_timer(cpu);
                break;
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                /*
                 * Even if all the cpus of a node are down, we don't free the
                 * kmem_list3 of any cache. This to avoid a race between
                 * cpu_down, and a kmalloc allocation from another cpu for
                 * memory from the node of the cpu going down.  The list3
                 * structure is usually allocated from kmem_cache_create() and
                 * gets destroyed at kmem_cache_destroy().
                 */
                /* fall through */
#endif
        case CPU_UP_CANCELED:
        case CPU_UP_CANCELED_FROZEN:
                mutex_lock(&cache_chain_mutex);
                cpuup_canceled(cpu);
                mutex_unlock(&cache_chain_mutex);
                break;
        }
        return err ? NOTIFY_BAD : NOTIFY_OK;
}

static struct notifier_block __cpuinitdata cpucache_notifier = {
        &cpuup_callback, NULL, 0
};

/*
 * swap the static kmem_list3 with kmalloced memory
 */
static void init_list(struct kmem_cache *cachep, struct kmem_list3 *list,
                        int nodeid)
{
        struct kmem_list3 *ptr;

        ptr = kmalloc_node(sizeof(struct kmem_list3), GFP_KERNEL, nodeid);
        BUG_ON(!ptr);

        local_irq_disable();
        memcpy(ptr, list, sizeof(struct kmem_list3));
        /*
         * Do not assume that spinlocks can be initialized via memcpy:
         */
        spin_lock_init(&ptr->list_lock);

        MAKE_ALL_LISTS(cachep, ptr, nodeid);
        cachep->nodelists[nodeid] = ptr;
        local_irq_enable();
}

/*
 * For setting up all the kmem_list3s for cache whose buffer_size is same as
 * size of kmem_list3.
 */
static void __init set_up_list3s(struct kmem_cache *cachep, int index)
{
        int node;

        for_each_online_node(node) {
                cachep->nodelists[node] = &initkmem_list3[index + node];
                cachep->nodelists[node]->next_reap = jiffies +
                    REAPTIMEOUT_LIST3 +
                    ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
        }
}

/*
 * Initialisation.  Called after the page allocator have been initialised and
 * before smp_init().
 */
void __init kmem_cache_init(void)
{
        size_t left_over;
        struct cache_sizes *sizes;
        struct cache_names *names;
        int i;
        int order;
        int node;

        if (num_possible_nodes() == 1) {
                use_alien_caches = 0;
                numa_platform = 0;
        }

        for (i = 0; i < NUM_INIT_LISTS; i++) {
                kmem_list3_init(&initkmem_list3[i]);
                if (i < MAX_NUMNODES)
                        cache_cache.nodelists[i] = NULL;
        }
        set_up_list3s(&cache_cache, CACHE_CACHE);

        /*
         * Fragmentation resistance on low memory - only use bigger
         * page orders on machines with more than 32MB of memory.
         */
        if (num_physpages > (32 << 20) >> PAGE_SHIFT)
                slab_break_gfp_order = BREAK_GFP_ORDER_HI;

        /* Bootstrap is tricky, because several objects are allocated
         * from caches that do not exist yet:
         * 1) initialize the cache_cache cache: it contains the struct
         *    kmem_cache structures of all caches, except cache_cache itself:
         *    cache_cache is statically allocated.
         *    Initially an __init data area is used for the head array and the
         *    kmem_list3 structures, it's replaced with a kmalloc allocated
         *    array at the end of the bootstrap.
         * 2) Create the first kmalloc cache.
         *    The struct kmem_cache for the new cache is allocated normally.
         *    An __init data area is used for the head array.
         * 3) Create the remaining kmalloc caches, with minimally sized
         *    head arrays.
         * 4) Replace the __init data head arrays for cache_cache and the first
         *    kmalloc cache with kmalloc allocated arrays.
         * 5) Replace the __init data for kmem_list3 for cache_cache and
         *    the other cache's with kmalloc allocated memory.
         * 6) Resize the head arrays of the kmalloc caches to their final sizes.
         */

        node = numa_node_id();

        /* 1) create the cache_cache */
        INIT_LIST_HEAD(&cache_chain);
        list_add(&cache_cache.next, &cache_chain);
        cache_cache.colour_off = cache_line_size();
        cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
        cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];

        /*
         * struct kmem_cache size depends on nr_node_ids, which
         * can be less than MAX_NUMNODES.
         */
        cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
                                 nr_node_ids * sizeof(struct kmem_list3 *);
#if DEBUG
        cache_cache.obj_size = cache_cache.buffer_size;
#endif
        cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
                                        cache_line_size());
        cache_cache.reciprocal_buffer_size =
                reciprocal_value(cache_cache.buffer_size);

        for (order = 0; order < MAX_ORDER; order++) {
                cache_estimate(order, cache_cache.buffer_size,
                        cache_line_size(), 0, &left_over, &cache_cache.num);
                if (cache_cache.num)
                        break;
        }
        BUG_ON(!cache_cache.num);
        cache_cache.gfporder = order;
        cache_cache.colour = left_over / cache_cache.colour_off;
        cache_cache.slab_size = ALIGN(cache_cache.num * sizeof(kmem_bufctl_t) +
                                      sizeof(struct slab), cache_line_size());

        /* 2+3) create the kmalloc caches */
        sizes = malloc_sizes;
        names = cache_names;

        /*
         * Initialize the caches that provide memory for the array cache and the
         * kmem_list3 structures first.  Without this, further allocations will
         * bug.
         */

        sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
                                        sizes[INDEX_AC].cs_size,
                                        ARCH_KMALLOC_MINALIGN,
                                        ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                        NULL);

        if (INDEX_AC != INDEX_L3) {
                sizes[INDEX_L3].cs_cachep =
                        kmem_cache_create(names[INDEX_L3].name,
                                sizes[INDEX_L3].cs_size,
                                ARCH_KMALLOC_MINALIGN,
                                ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                NULL);
        }

        slab_early_init = 0;

        while (sizes->cs_size != ULONG_MAX) {
                /*
                 * For performance, all the general caches are L1 aligned.
                 * This should be particularly beneficial on SMP boxes, as it
                 * eliminates "false sharing".
                 * Note for systems short on memory removing the alignment will
                 * allow tighter packing of the smaller caches.
                 */
                if (!sizes->cs_cachep) {
                        sizes->cs_cachep = kmem_cache_create(names->name,
                                        sizes->cs_size,
                                        ARCH_KMALLOC_MINALIGN,
                                        ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                        NULL);
                }
#ifdef CONFIG_ZONE_DMA
                sizes->cs_dmacachep = kmem_cache_create(
                                        names->name_dma,
                                        sizes->cs_size,
                                        ARCH_KMALLOC_MINALIGN,
                                        ARCH_KMALLOC_FLAGS|SLAB_CACHE_DMA|
                                                SLAB_PANIC,
                                        NULL);
#endif
                sizes++;
                names++;
        }
        /* 4) Replace the bootstrap head arrays */
        {
                struct array_cache *ptr;

                ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);

                local_irq_disable();
                BUG_ON(cpu_cache_get(&cache_cache) != &initarray_cache.cache);
                memcpy(ptr, cpu_cache_get(&cache_cache),
                       sizeof(struct arraycache_init));
                /*
                 * Do not assume that spinlocks can be initialized via memcpy:
                 */
                spin_lock_init(&ptr->lock);

                cache_cache.array[smp_processor_id()] = ptr;
                local_irq_enable();

                ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);

                local_irq_disable();
                BUG_ON(cpu_cache_get(malloc_sizes[INDEX_AC].cs_cachep)
                       != &initarray_generic.cache);
                memcpy(ptr, cpu_cache_get(malloc_sizes[INDEX_AC].cs_cachep),
                       sizeof(struct arraycache_init));
                /*
                 * Do not assume that spinlocks can be initialized via memcpy:
                 */
                spin_lock_init(&ptr->lock);

                malloc_sizes[INDEX_AC].cs_cachep->array[smp_processor_id()] =
                    ptr;
                local_irq_enable();
        }
        /* 5) Replace the bootstrap kmem_list3's */
        {
                int nid;

                for_each_online_node(nid) {
                        init_list(&cache_cache, &initkmem_list3[CACHE_CACHE + nid], nid);

                        init_list(malloc_sizes[INDEX_AC].cs_cachep,
                                  &initkmem_list3[SIZE_AC + nid], nid);

                        if (INDEX_AC != INDEX_L3) {
                                init_list(malloc_sizes[INDEX_L3].cs_cachep,
                                          &initkmem_list3[SIZE_L3 + nid], nid);
                        }
                }
        }

        /* 6) resize the head arrays to their final sizes */
        {
                struct kmem_cache *cachep;
                mutex_lock(&cache_chain_mutex);
                list_for_each_entry(cachep, &cache_chain, next)
                        if (enable_cpucache(cachep))
                                BUG();
                mutex_unlock(&cache_chain_mutex);
        }

        /* Annotate slab for lockdep -- annotate the malloc caches */
        init_lock_keys();


        /* Done! */
        g_cpucache_up = FULL;

        /*
         * Register a cpu startup notifier callback that initializes
         * cpu_cache_get for all new cpus
         */
        register_cpu_notifier(&cpucache_notifier);

        /*
         * The reap timers are started later, with a module init call: That part
         * of the kernel is not yet operational.
         */
}

static int __init cpucache_init(void)
{
        int cpu;

        /*
         * Register the timers that return unneeded pages to the page allocator
         */
        for_each_online_cpu(cpu)
                start_cpu_timer(cpu);
        return 0;
}
__initcall(cpucache_init);

/*
 * Interface to system's page allocator. No need to hold the cache-lock.
 *
 * If we requested dmaable memory, we will get it. Even if we
 * did not request dmaable memory, we might get it, but that
 * would be relatively rare and ignorable.
 */
static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
{
        struct page *page;
        int nr_pages;
        int i;

#ifndef CONFIG_MMU
        /*
         * Nommu uses slab's for process anonymous memory allocations, and thus
         * requires __GFP_COMP to properly refcount higher order allocations
         */
        flags |= __GFP_COMP;
#endif

        flags |= cachep->gfpflags;
        if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                flags |= __GFP_RECLAIMABLE;

        page = alloc_pages_node(nodeid, flags, cachep->gfporder);
        if (!page)
                return NULL;

        nr_pages = (1 << cachep->gfporder);
        if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                add_zone_page_state(page_zone(page),
                        NR_SLAB_RECLAIMABLE, nr_pages);
        else
                add_zone_page_state(page_zone(page),
                        NR_SLAB_UNRECLAIMABLE, nr_pages);
        for (i = 0; i < nr_pages; i++)
                __SetPageSlab(page + i);
        return page_address(page);
}

/*
 * Interface to system's page release.
 */
static void kmem_freepages(struct kmem_cache *cachep, void *addr)
{
        unsigned long i = (1 << cachep->gfporder);
        struct page *page = virt_to_page(addr);
        const unsigned long nr_freed = i;

        if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                sub_zone_page_state(page_zone(page),
                                NR_SLAB_RECLAIMABLE, nr_freed);
        else
                sub_zone_page_state(page_zone(page),
                                NR_SLAB_UNRECLAIMABLE, nr_freed);
        while (i--) {
                BUG_ON(!PageSlab(page));
                __ClearPageSlab(page);
                page++;
        }
        if (current->reclaim_state)
                current->reclaim_state->reclaimed_slab += nr_freed;
        free_pages((unsigned long)addr, cachep->gfporder);
}

static void kmem_rcu_free(struct rcu_head *head)
{
        struct slab_rcu *slab_rcu = (struct slab_rcu *)head;
        struct kmem_cache *cachep = slab_rcu->cachep;

        kmem_freepages(cachep, slab_rcu->addr);
        if (OFF_SLAB(cachep))
                kmem_cache_free(cachep->slabp_cache, slab_rcu);
}

#if DEBUG

#ifdef CONFIG_DEBUG_PAGEALLOC
static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
                            unsigned long caller)
{
        int size = obj_size(cachep);

        addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];

        if (size < 5 * sizeof(unsigned long))
                return;

        *addr++ = 0x12345678;
        *addr++ = caller;
        *addr++ = smp_processor_id();
        size -= 3 * sizeof(unsigned long);
        {
                unsigned long *sptr = &caller;
                unsigned long svalue;

                while (!kstack_end(sptr)) {
                        svalue = *sptr++;
                        if (kernel_text_address(svalue)) {
                                *addr++ = svalue;
                                size -= sizeof(unsigned long);
                                if (size <= sizeof(unsigned long))
                                        break;
                        }
                }

        }
        *addr++ = 0x87654321;
}
#endif

static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
{
        int size = obj_size(cachep);
        addr = &((char *)addr)[obj_offset(cachep)];

        memset(addr, val, size);
        *(unsigned char *)(addr + size - 1) = POISON_END;
}

static void dump_line(char *data, int offset, int limit)
{
        int i;
        unsigned char error = 0;
        int bad_count = 0;

        printk(KERN_ERR "%03x:", offset);
        for (i = 0; i < limit; i++) {
                if (data[offset + i] != POISON_FREE) {
                        error = data[offset + i];
                        bad_count++;
                }
                printk(" %02x", (unsigned char)data[offset + i]);
        }
        printk("\n");

        if (bad_count == 1) {
                error ^= POISON_FREE;
                if (!(error & (error - 1))) {
                        printk(KERN_ERR "Single bit error detected. Probably "
                                        "bad RAM.\n");
#ifdef CONFIG_X86
                        printk(KERN_ERR "Run memtest86+ or a similar memory "
                                        "test tool.\n");
#else
                        printk(KERN_ERR "Run a memory test tool.\n");
#endif
                }
        }
}
#endif

#if DEBUG

static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
{
        int i, size;
        char *realobj;

        if (cachep->flags & SLAB_RED_ZONE) {
                printk(KERN_ERR "Redzone: 0x%llx/0x%llx.\n",
                        *dbg_redzone1(cachep, objp),
                        *dbg_redzone2(cachep, objp));
        }

        if (cachep->flags & SLAB_STORE_USER) {
                printk(KERN_ERR "Last user: [<%p>]",
                        *dbg_userword(cachep, objp));
                print_symbol("(%s)",
                                (unsigned long)*dbg_userword(cachep, objp));
                printk("\n");
        }
        realobj = (char *)objp + obj_offset(cachep);
        size = obj_size(cachep);
        for (i = 0; i < size && lines; i += 16, lines--) {
                int limit;
                limit = 16;
                if (i + limit > size)
                        limit = size - i;
                dump_line(realobj, i, limit);
        }
}

static void check_poison_obj(struct kmem_cache *cachep, void *objp)
{
        char *realobj;
        int size, i;
        int lines = 0;

        realobj = (char *)objp + obj_offset(cachep);
        size = obj_size(cachep);

        for (i = 0; i < size; i++) {
                char exp = POISON_FREE;
                if (i == size - 1)
                        exp = POISON_END;
                if (realobj[i] != exp) {
                        int limit;
                        /* Mismatch ! */
                        /* Print header */
                        if (lines == 0) {
                                printk(KERN_ERR
                                        "Slab corruption: %s start=%p, len=%d\n",
                                        cachep->name, realobj, size);
                                print_objinfo(cachep, objp, 0);
                        }
                        /* Hexdump the affected line */
                        i = (i / 16) * 16;
                        limit = 16;
                        if (i + limit > size)
                                limit = size - i;
                        dump_line(realobj, i, limit);
                        i += 16;
                        lines++;
                        /* Limit to 5 lines */
                        if (lines > 5)
                                break;
                }
        }
        if (lines != 0) {
                /* Print some data about the neighboring objects, if they
                 * exist:
                 */
                struct slab *slabp = virt_to_slab(objp);
                unsigned int objnr;

                objnr = obj_to_index(cachep, slabp, objp);
                if (objnr) {
                        objp = index_to_obj(cachep, slabp, objnr - 1);
                        realobj = (char *)objp + obj_offset(cachep);
                        printk(KERN_ERR "Prev obj: start=%p, len=%d\n",
                               realobj, size);
                        print_objinfo(cachep, objp, 2);
                }
                if (objnr + 1 < cachep->num) {
                        objp = index_to_obj(cachep, slabp, objnr + 1);
                        realobj = (char *)objp + obj_offset(cachep);
                        printk(KERN_ERR "Next obj: start=%p, len=%d\n",
                               realobj, size);
                        print_objinfo(cachep, objp, 2);
                }
        }
}
#endif

#if DEBUG
static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slabp)
{
        int i;
        for (i = 0; i < cachep->num; i++) {
                void *objp = index_to_obj(cachep, slabp, i);

                if (cachep->flags & SLAB_POISON) {
#ifdef CONFIG_DEBUG_PAGEALLOC
                        if (cachep->buffer_size % PAGE_SIZE == 0 &&
                                        OFF_SLAB(cachep))
                                kernel_map_pages(virt_to_page(objp),
                                        cachep->buffer_size / PAGE_SIZE, 1);
                        else
                                check_poison_obj(cachep, objp);
#else
                        check_poison_obj(cachep, objp);
#endif
                }
                if (cachep->flags & SLAB_RED_ZONE) {
                        if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
                                slab_error(cachep, "start of a freed object "
                                           "was overwritten");
                        if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
                                slab_error(cachep, "end of a freed object "
                                           "was overwritten");
                }
        }
}
#else
static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slabp)
{
}
#endif

/**
 * slab_destroy - destroy and release all objects in a slab
 * @cachep: cache pointer being destroyed
 * @slabp: slab pointer being destroyed
 *
 * Destroy all the objs in a slab, and release the mem back to the system.
 * Before calling the slab must have been unlinked from the cache.  The
 * cache-lock is not held/needed.
 */
static void slab_destroy(struct kmem_cache *cachep, struct slab *slabp)
{
        void *addr = slabp->s_mem - slabp->colouroff;

        slab_destroy_debugcheck(cachep, slabp);
        if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) {
                struct slab_rcu *slab_rcu;

                slab_rcu = (struct slab_rcu *)slabp;
                slab_rcu->cachep = cachep;
                slab_rcu->addr = addr;
                call_rcu(&slab_rcu->head, kmem_rcu_free);
        } else {
                kmem_freepages(cachep, addr);
                if (OFF_SLAB(cachep))
                        kmem_cache_free(cachep->slabp_cache, slabp);
        }
}

static void __kmem_cache_destroy(struct kmem_cache *cachep)
{
        int i;
        struct kmem_list3 *l3;

        for_each_online_cpu(i)
            kfree(cachep->array[i]);

        /* NUMA: free the list3 structures */
        for_each_online_node(i) {
                l3 = cachep->nodelists[i];
                if (l3) {
                        kfree(l3->shared);
                        free_alien_cache(l3->alien);
                        kfree(l3);
                }
        }
        kmem_cache_free(&cache_cache, cachep);
}


/**
 * calculate_slab_order - calculate size (page order) of slabs
 * @cachep: pointer to the cache that is being created
 * @size: size of objects to be created in this cache.

 * @align: required alignment for the objects.
 * @flags: slab allocation flags
 *
 * Also calculates the number of objects per slab.
 *
 * This could be made much more intelligent.  For now, try to avoid using
 * high order pages for slabs.  When the gfp() functions are more friendly
 * towards high-order requests, this should be changed.
 */
static size_t calculate_slab_order(struct kmem_cache *cachep,
                        size_t size, size_t align, unsigned long flags)
{
        unsigned long offslab_limit;
        size_t left_over = 0;
        int gfporder;

        for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
                unsigned int num;
                size_t remainder;

                cache_estimate(gfporder, size, align, flags, &remainder, &num);
                if (!num)
                        continue;

                if (flags & CFLGS_OFF_SLAB) {
                        /*
                         * Max number of objs-per-slab for caches which
                         * use off-slab slabs. Needed to avoid a possible
                         * looping condition in cache_grow().
                         */
                        offslab_limit = size - sizeof(struct slab);
                        offslab_limit /= sizeof(kmem_bufctl_t);

                        if (num > offslab_limit)
                                break;
                }

                /* Found something acceptable - save it away */
                cachep->num = num;
                cachep->gfporder = gfporder;
                left_over = remainder;

                /*
                 * A VFS-reclaimable slab tends to have most allocations
                 * as GFP_NOFS and we really don't want to have to be allocating
                 * higher-order pages when we are unable to shrink dcache.
                 */
                if (flags & SLAB_RECLAIM_ACCOUNT)
                        break;

                /*
                 * Large number of objects is good, but very large slabs are
                 * currently bad for the gfp()s.
                 */
                if (gfporder >= slab_break_gfp_order)
                        break;

                /*
                 * Acceptable internal fragmentation?
                 */
                if (left_over * 8 <= (PAGE_SIZE << gfporder))
                        break;
        }
        return left_over;
}

static int __init_refok setup_cpu_cache(struct kmem_cache *cachep)
{
        if (g_cpucache_up == FULL)
                return enable_cpucache(cachep);

        if (g_cpucache_up == NONE) {
                /*
                 * Note: the first kmem_cache_create must create the cache
                 * that's used by kmalloc(24), otherwise the creation of
                 * further caches will BUG().
                 */
                cachep->array[smp_processor_id()] = &initarray_generic.cache;

                /*
                 * If the cache that's used by kmalloc(sizeof(kmem_list3)) is
                 * the first cache, then we need to set up all its list3s,
                 * otherwise the creation of further caches will BUG().
                 */
                set_up_list3s(cachep, SIZE_AC);
                if (INDEX_AC == INDEX_L3)
                        g_cpucache_up = PARTIAL_L3;
                else
                        g_cpucache_up = PARTIAL_AC;
        } else {
                cachep->array[smp_processor_id()] =
                        kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);

                if (g_cpucache_up == PARTIAL_AC) {
                        set_up_list3s(cachep, SIZE_L3);
                        g_cpucache_up = PARTIAL_L3;
                } else {
                        int node;
                        for_each_online_node(node) {
                                cachep->nodelists[node] =
                                    kmalloc_node(sizeof(struct kmem_list3),
                                                GFP_KERNEL, node);
                                BUG_ON(!cachep->nodelists[node]);
                                kmem_list3_init(cachep->nodelists[node]);
                        }
                }
        }
        cachep->nodelists[numa_node_id()]->next_reap =
                        jiffies + REAPTIMEOUT_LIST3 +
                        ((unsigned long)cachep) % REAPTIMEOUT_LIST3;

        cpu_cache_get(cachep)->avail = 0;
        cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
        cpu_cache_get(cachep)->batchcount = 1;
        cpu_cache_get(cachep)->touched = 0;
        cachep->batchcount = 1;
        cachep->limit = BOOT_CPUCACHE_ENTRIES;
        return 0;
}

/**
 * kmem_cache_create - Create a cache.
 * @name: A string which is used in /proc/slabinfo to identify this cache.
 * @size: The size of objects to be created in this cache.
 * @align: The required alignment for the objects.
 * @flags: SLAB flags
 * @ctor: A constructor for the objects.
 *
 * Returns a ptr to the cache on success, NULL on failure.
 * Cannot be called within a int, but can be interrupted.
 * The @ctor is run when new pages are allocated by the cache.
 *
 * @name must be valid until the cache is destroyed. This implies that
 * the module calling this has to destroy the cache before getting unloaded.
 * Note that kmem_cache_name() is not guaranteed to return the same pointer,
 * therefore applications must manage it themselves.
 *
 * The flags are
 *
 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
 * to catch references to uninitialised memory.
 *
 * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
 * for buffer overruns.
 *
 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
 * cacheline.  This can be beneficial if you're counting cycles as closely
 * as davem.
 */
struct kmem_cache *
kmem_cache_create (const char *name, size_t size, size_t align,
        unsigned long flags, void (*ctor)(void *))
{
        size_t left_over, slab_size, ralign;
        struct kmem_cache *cachep = NULL, *pc;

        /*
         * Sanity checks... these are all serious usage bugs.
         */
        if (!name || in_interrupt() || (size < BYTES_PER_WORD) ||
            size > KMALLOC_MAX_SIZE) {
                printk(KERN_ERR "%s: Early error in slab %s\n", __func__,
                                name);
                BUG();
        }

        /*
         * We use cache_chain_mutex to ensure a consistent view of
         * cpu_online_mask as well.  Please see cpuup_callback
         */
        get_online_cpus();
        mutex_lock(&cache_chain_mutex);

        list_for_each_entry(pc, &cache_chain, next) {
                char tmp;
                int res;

                /*
                 * This happens when the module gets unloaded and doesn't
                 * destroy its slab cache and no-one else reuses the vmalloc
                 * area of the module.  Print a warning.
                 */
                res = probe_kernel_address(pc->name, tmp);
                if (res) {
                        printk(KERN_ERR
                               "SLAB: cache with size %d has lost its name\n",
                               pc->buffer_size);
                        continue;
                }

                if (!strcmp(pc->name, name)) {
                        printk(KERN_ERR
                               "kmem_cache_create: duplicate cache %s\n", name);
                        dump_stack();
                        goto oops;
                }
        }

#if DEBUG
        WARN_ON(strchr(name, ' '));     /* It confuses parsers */
#if FORCED_DEBUG
        /*
         * Enable redzoning and last user accounting, except for caches with
         * large objects, if the increased size would increase the object size
         * above the next power of two: caches with object sizes just above a
         * power of two have a significant amount of internal fragmentation.
         */
        if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
                                                2 * sizeof(unsigned long long)))
                flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
        if (!(flags & SLAB_DESTROY_BY_RCU))
                flags |= SLAB_POISON;
#endif
        if (flags & SLAB_DESTROY_BY_RCU)
                BUG_ON(flags & SLAB_POISON);
#endif
        /*
         * Always checks flags, a caller might be expecting debug support which
         * isn't available.
         */
        BUG_ON(flags & ~CREATE_MASK);

        /*
         * Check that size is in terms of words.  This is needed to avoid
         * unaligned accesses for some archs when redzoning is used, and makes
         * sure any on-slab bufctl's are also correctly aligned.
         */
        if (size & (BYTES_PER_WORD - 1)) {
                size += (BYTES_PER_WORD - 1);
                size &= ~(BYTES_PER_WORD - 1);
        }

        /* calculate the final buffer alignment: */

        /* 1) arch recommendation: can be overridden for debug */
        if (flags & SLAB_HWCACHE_ALIGN) {
                /*
                 * Default alignment: as specified by the arch code.  Except if
                 * an object is really small, then squeeze multiple objects into
                 * one cacheline.
                 */
                ralign = cache_line_size();
                while (size <= ralign / 2)
                        ralign /= 2;
        } else {
                ralign = BYTES_PER_WORD;
        }

        /*
         * Redzoning and user store require word alignment or possibly larger.
         * Note this will be overridden by architecture or caller mandated
         * alignment if either is greater than BYTES_PER_WORD.
         */
        if (flags & SLAB_STORE_USER)
                ralign = BYTES_PER_WORD;

        if (flags & SLAB_RED_ZONE) {
                ralign = REDZONE_ALIGN;
                /* If redzoning, ensure that the second redzone is suitably
                 * aligned, by adjusting the object size accordingly. */
                size += REDZONE_ALIGN - 1;
                size &= ~(REDZONE_ALIGN - 1);
        }

        /* 2) arch mandated alignment */
        if (ralign < ARCH_SLAB_MINALIGN) {
                ralign = ARCH_SLAB_MINALIGN;
        }
        /* 3) caller mandated alignment */
        if (ralign < align) {
                ralign = align;
        }
        /* disable debug if necessary */
        if (ralign > __alignof__(unsigned long long))
                flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
        /*
         * 4) Store it.
         */
        align = ralign;

        /* Get cache's description obj. */
        cachep = kmem_cache_zalloc(&cache_cache, GFP_KERNEL);
        if (!cachep)
                goto oops;

#if DEBUG
        cachep->obj_size = size;

        /*
         * Both debugging options require word-alignment which is calculated
         * into align above.
         */
        if (flags & SLAB_RED_ZONE) {
                /* add space for red zone words */
                cachep->obj_offset += sizeof(unsigned long long);
                size += 2 * sizeof(unsigned long long);
        }
        if (flags & SLAB_STORE_USER) {
                /* user store requires one word storage behind the end of
                 * the real object. But if the second red zone needs to be
                 * aligned to 64 bits, we must allow that much space.
                 */
                if (flags & SLAB_RED_ZONE)
                        size += REDZONE_ALIGN;
                else
                        size += BYTES_PER_WORD;
        }
#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)
        if (size >= malloc_sizes[INDEX_L3 + 1].cs_size
            && cachep->obj_size > cache_line_size() && size < PAGE_SIZE) {
                cachep->obj_offset += PAGE_SIZE - size;
                size = PAGE_SIZE;
        }
#endif
#endif

        /*
         * Determine if the slab management is 'on' or 'off' slab.
         * (bootstrapping cannot cope with offslab caches so don't do
         * it too early on.)
         */
        if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init)
                /*
                 * Size is large, assume best to place the slab management obj
                 * off-slab (should allow better packing of objs).
                 */
                flags |= CFLGS_OFF_SLAB;

        size = ALIGN(size, align);

        left_over = calculate_slab_order(cachep, size, align, flags);

        if (!cachep->num) {
                printk(KERN_ERR
                       "kmem_cache_create: couldn't create cache %s.\n", name);
                kmem_cache_free(&cache_cache, cachep);
                cachep = NULL;
                goto oops;
        }
        slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
                          + sizeof(struct slab), align);

        /*
         * If the slab has been placed off-slab, and we have enough space then
         * move it on-slab. This is at the expense of any extra colouring.
         */
        if (flags & CFLGS_OFF_SLAB && left_over >= slab_size) {
                flags &= ~CFLGS_OFF_SLAB;
                left_over -= slab_size;
        }

        if (flags & CFLGS_OFF_SLAB) {
                /* really off slab. No need for manual alignment */
                slab_size =
                    cachep->num * sizeof(kmem_bufctl_t) + sizeof(struct slab);
        }

        cachep->colour_off = cache_line_size();
        /* Offset must be a multiple of the alignment. */
        if (cachep->colour_off < align)
                cachep->colour_off = align;
        cachep->colour = left_over / cachep->colour_off;
        cachep->slab_size = slab_size;
        cachep->flags = flags;
        cachep->gfpflags = 0;
        if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA))
                cachep->gfpflags |= GFP_DMA;
        cachep->buffer_size = size;
        cachep->reciprocal_buffer_size = reciprocal_value(size);

        if (flags & CFLGS_OFF_SLAB) {
                cachep->slabp_cache = kmem_find_general_cachep(slab_size, 0u);
                /*
                 * This is a possibility for one of the malloc_sizes caches.
                 * But since we go off slab only for object size greater than
                 * PAGE_SIZE/8, and malloc_sizes gets created in ascending order,
                 * this should not happen at all.
                 * But leave a BUG_ON for some lucky dude.
                 */
                BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));
        }
        cachep->ctor = ctor;
        cachep->name = name;

        if (setup_cpu_cache(cachep)) {
                __kmem_cache_destroy(cachep);
                cachep = NULL;
                goto oops;
        }

        /* cache setup completed, link it into the list */
        list_add(&cachep->next, &cache_chain);
oops:
        if (!cachep && (flags & SLAB_PANIC))
                panic("kmem_cache_create(): failed to create slab `%s'\n",
                      name);
        mutex_unlock(&cache_chain_mutex);
        put_online_cpus();
        return cachep;
}
EXPORT_SYMBOL(kmem_cache_create);

#if DEBUG
static void check_irq_off(void)
{
        BUG_ON(!irqs_disabled());
}

static void check_irq_on(void)
{
        BUG_ON(irqs_disabled());
}

static void check_spinlock_acquired(struct kmem_cache *cachep)
{
#ifdef CONFIG_SMP
        check_irq_off();
        assert_spin_locked(&cachep->nodelists[numa_node_id()]->list_lock);
#endif
}

static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
{
#ifdef CONFIG_SMP
        check_irq_off();
        assert_spin_locked(&cachep->nodelists[node]->list_lock);
#endif
}

#else
#define check_irq_off() do { } while(0)
#define check_irq_on()  do { } while(0)
#define check_spinlock_acquired(x) do { } while(0)
#define check_spinlock_acquired_node(x, y) do { } while(0)
#endif

static void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
                        struct array_cache *ac,
                        int force, int node);

static void do_drain(void *arg)
{
        struct kmem_cache *cachep = arg;
        struct array_cache *ac;
        int node = numa_node_id();

        check_irq_off();
        ac = cpu_cache_get(cachep);
        spin_lock(&cachep->nodelists[node]->list_lock);
        free_block(cachep, ac->entry, ac->avail, node);
        spin_unlock(&cachep->nodelists[node]->list_lock);
        ac->avail = 0;
}

static void drain_cpu_caches(struct kmem_cache *cachep)
{
        struct kmem_list3 *l3;
        int node;

        on_each_cpu(do_drain, cachep, 1);
        check_irq_on();
        for_each_online_node(node) {
                l3 = cachep->nodelists[node];
                if (l3 && l3->alien)
                        drain_alien_cache(cachep, l3->alien);
        }

        for_each_online_node(node) {
                l3 = cachep->nodelists[node];
                if (l3)
                        drain_array(cachep, l3, l3->shared, 1, node);
        }
}

/*
 * Remove slabs from the list of free slabs.
 * Specify the number of slabs to drain in tofree.
 *
 * Returns the actual number of slabs released.
 */
static int drain_freelist(struct kmem_cache *cache,
                        struct kmem_list3 *l3, int tofree)
{
        struct list_head *p;
        int nr_freed;
        struct slab *slabp;

        nr_freed = 0;
        while (nr_freed < tofree && !list_empty(&l3->slabs_free)) {

                spin_lock_irq(&l3->list_lock);
                p = l3->slabs_free.prev;
                if (p == &l3->slabs_free) {
                        spin_unlock_irq(&l3->list_lock);
                        goto out;
                }

                slabp = list_entry(p, struct slab, list);
#if DEBUG
                BUG_ON(slabp->inuse);
#endif
                list_del(&slabp->list);
                /*
                 * Safe to drop the lock. The slab is no longer linked
                 * to the cache.
                 */
                l3->free_objects -= cache->num;
                spin_unlock_irq(&l3->list_lock);
                slab_destroy(cache, slabp);
                nr_freed++;
        }
out:
        return nr_freed;
}

/* Called with cache_chain_mutex held to protect against cpu hotplug */
static int __cache_shrink(struct kmem_cache *cachep)
{
        int ret = 0, i = 0;
        struct kmem_list3 *l3;

        drain_cpu_caches(cachep);

        check_irq_on();
        for_each_online_node(i) {
                l3 = cachep->nodelists[i];
                if (!l3)
                        continue;

                drain_freelist(cachep, l3, l3->free_objects);

                ret += !list_empty(&l3->slabs_full) ||
                        !list_empty(&l3->slabs_partial);
        }
        return (ret ? 1 : 0);
}

/**
 * kmem_cache_shrink - Shrink a cache.
 * @cachep: The cache to shrink.
 *
 * Releases as many slabs as possible for a cache.
 * To help debugging, a zero exit status indicates all slabs were released.
 */
int kmem_cache_shrink(struct kmem_cache *cachep)
{
        int ret;
        BUG_ON(!cachep || in_interrupt());

        get_online_cpus();
        mutex_lock(&cache_chain_mutex);
        ret = __cache_shrink(cachep);
        mutex_unlock(&cache_chain_mutex);
        put_online_cpus();
        return ret;
}
EXPORT_SYMBOL(kmem_cache_shrink);

/**
 * kmem_cache_destroy - delete a cache
 * @cachep: the cache to destroy
 *
 * Remove a &struct kmem_cache object from the slab cache.
 *
 * It is expected this function will be called by a module when it is
 * unloaded.  This will remove the cache completely, and avoid a duplicate
 * cache being allocated each time a module is loaded and unloaded, if the
 * module doesn't have persistent in-kernel storage across loads and unloads.
 *
 * The cache must be empty before calling this function.
 *
 * The caller must guarantee that noone will allocate memory from the cache
 * during the kmem_cache_destroy().
 */
void kmem_cache_destroy(struct kmem_cache *cachep)
{
        BUG_ON(!cachep || in_interrupt());

        /* Find the cache in the chain of caches. */
        get_online_cpus();
        mutex_lock(&cache_chain_mutex);
        /*
         * the chain is never empty, cache_cache is never destroyed
         */
        list_del(&cachep->next);
        if (__cache_shrink(cachep)) {
                slab_error(cachep, "Can't free all objects");
                list_add(&cachep->next, &cache_chain);
                mutex_unlock(&cache_chain_mutex);
                put_online_cpus();
                return;
        }

        if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
                rcu_barrier();

        __kmem_cache_destroy(cachep);
        mutex_unlock(&cache_chain_mutex);
        put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_destroy);

/*
 * Get the memory for a slab management obj.
 * For a slab cache when the slab descriptor is off-slab, slab descriptors
 * always come from malloc_sizes caches.  The slab descriptor cannot
 * come from the same cache which is getting created because,
 * when we are searching for an appropriate cache for these
 * descriptors in kmem_cache_create, we search through the malloc_sizes array.
 * If we are creating a malloc_sizes cache here it would not be visible to
 * kmem_find_general_cachep till the initialization is complete.
 * Hence we cannot have slabp_cache same as the original cache.
 */
static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
                                   int colour_off, gfp_t local_flags,
                                   int nodeid)
{
        struct slab *slabp;

        if (OFF_SLAB(cachep)) {
                /* Slab management obj is off-slab. */
                slabp = kmem_cache_alloc_node(cachep->slabp_cache,
                                              local_flags, nodeid);
                if (!slabp)
                        return NULL;
        } else {
                slabp = objp + colour_off;
                colour_off += cachep->slab_size;
        }
        slabp->inuse = 0;
        slabp->colouroff = colour_off;
        slabp->s_mem = objp + colour_off;
        slabp->nodeid = nodeid;
        slabp->free = 0;
        return slabp;
}

static inline kmem_bufctl_t *slab_bufctl(struct slab *slabp)
{
        return (kmem_bufctl_t *) (slabp + 1);
}

static void cache_init_objs(struct kmem_cache *cachep,
                            struct slab *slabp)
{
        int i;

        for (i = 0; i < cachep->num; i++) {
                void *objp = index_to_obj(cachep, slabp, i);
#if DEBUG
                /* need to poison the objs? */
                if (cachep->flags & SLAB_POISON)
                        poison_obj(cachep, objp, POISON_FREE);
                if (cachep->flags & SLAB_STORE_USER)
                        *dbg_userword(cachep, objp) = NULL;

                if (cachep->flags & SLAB_RED_ZONE) {
                        *dbg_redzone1(cachep, objp) = RED_INACTIVE;
                        *dbg_redzone2(cachep, objp) = RED_INACTIVE;
                }
                /*
                 * Constructors are not allowed to allocate memory from the same
                 * cache which they are a constructor for.  Otherwise, deadlock.
                 * They must also be threaded.
                 */
                if (cachep->ctor && !(cachep->flags & SLAB_POISON))
                        cachep->ctor(objp + obj_offset(cachep));

                if (cachep->flags & SLAB_RED_ZONE) {
                        if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
                                slab_error(cachep, "constructor overwrote the"
                                           " end of an object");
                        if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
                                slab_error(cachep, "constructor overwrote the"
                                           " start of an object");
                }
                if ((cachep->buffer_size % PAGE_SIZE) == 0 &&
                            OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
                        kernel_map_pages(virt_to_page(objp),
                                         cachep->buffer_size / PAGE_SIZE, 0);
#else
                if (cachep->ctor)
                        cachep->ctor(objp);
#endif
                slab_bufctl(slabp)[i] = i + 1;
        }
        slab_bufctl(slabp)[i - 1] = BUFCTL_END;
}

static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
{
        if (CONFIG_ZONE_DMA_FLAG) {
                if (flags & GFP_DMA)
                        BUG_ON(!(cachep->gfpflags & GFP_DMA));
                else
                        BUG_ON(cachep->gfpflags & GFP_DMA);
        }
}

static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slabp,
                                int nodeid)
{
        void *objp = index_to_obj(cachep, slabp, slabp->free);
        kmem_bufctl_t next;

        slabp->inuse++;
        next = slab_bufctl(slabp)[slabp->free];
#if DEBUG
        slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE;
        WARN_ON(slabp->nodeid != nodeid);
#endif
        slabp->free = next;

        return objp;
}

static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
                                void *objp, int nodeid)
{
        unsigned int objnr = obj_to_index(cachep, slabp, objp);

#if DEBUG
        /* Verify that the slab belongs to the intended node */
        WARN_ON(slabp->nodeid != nodeid);

        if (slab_bufctl(slabp)[objnr] + 1 <= SLAB_LIMIT + 1) {
                printk(KERN_ERR "slab: double free detected in cache "
                                "'%s', objp %p\n", cachep->name, objp);
                BUG();
        }
#endif
        slab_bufctl(slabp)[objnr] = slabp->free;
        slabp->free = objnr;
        slabp->inuse--;
}

/*
 * Map pages beginning at addr to the given cache and slab. This is required
 * for the slab allocator to be able to lookup the cache and slab of a
 * virtual address for kfree, ksize, kmem_ptr_validate, and slab debugging.
 */
static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
                           void *addr)
{
        int nr_pages;
        struct page *page;

        page = virt_to_page(addr);

        nr_pages = 1;
        if (likely(!PageCompound(page)))
                nr_pages <<= cache->gfporder;

        do {
                page_set_cache(page, cache);
                page_set_slab(page, slab);
                page++;
        } while (--nr_pages);
}

/*
 * Grow (by 1) the number of slabs within a cache.  This is called by
 * kmem_cache_alloc() when there are no active objs left in a cache.
 */
static int cache_grow(struct kmem_cache *cachep,
                gfp_t flags, int nodeid, void *objp)
{
        struct slab *slabp;
        size_t offset;
        gfp_t local_flags;
        struct kmem_list3 *l3;

        /*
         * Be lazy and only check for valid flags here,  keeping it out of the
         * critical path in kmem_cache_alloc().
         */
        BUG_ON(flags & GFP_SLAB_BUG_MASK);
        local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);

        /* Take the l3 list lock to change the colour_next on this node */
        check_irq_off();
        l3 = cachep->nodelists[nodeid];
        spin_lock(&l3->list_lock);

        /* Get colour for the slab, and cal the next value. */
        offset = l3->colour_next;
        l3->colour_next++;
        if (l3->colour_next >= cachep->colour)
                l3->colour_next = 0;
        spin_unlock(&l3->list_lock);

        offset *= cachep->colour_off;

        if (local_flags & __GFP_WAIT)
                local_irq_enable();

        /*
         * The test for missing atomic flag is performed here, rather than
         * the more obvious place, simply to reduce the critical path length
         * in kmem_cache_alloc(). If a caller is seriously mis-behaving they
         * will eventually be caught here (where it matters).
         */
        kmem_flagcheck(cachep, flags);

        /*
         * Get mem for the objs.  Attempt to allocate a physical page from
         * 'nodeid'.
         */
        if (!objp)
                objp = kmem_getpages(cachep, local_flags, nodeid);
        if (!objp)
                goto failed;

        /* Get slab management. */
        slabp = alloc_slabmgmt(cachep, objp, offset,
                        local_flags & ~GFP_CONSTRAINT_MASK, nodeid);
        if (!slabp)
                goto opps1;

        slab_map_pages(cachep, slabp, objp);

        cache_init_objs(cachep, slabp);

        if (local_flags & __GFP_WAIT)
                local_irq_disable();
        check_irq_off();
        spin_lock(&l3->list_lock);

        /* Make slab active. */
        list_add_tail(&slabp->list, &(l3->slabs_free));
        STATS_INC_GROWN(cachep);
        l3->free_objects += cachep->num;
        spin_unlock(&l3->list_lock);
        return 1;
opps1:
        kmem_freepages(cachep, objp);
failed:
        if (local_flags & __GFP_WAIT)
                local_irq_disable();
        return 0;
}

#if DEBUG

/*
 * Perform extra freeing checks:
 * - detect bad pointers.
 * - POISON/RED_ZONE checking
 */
static void kfree_debugcheck(const void *objp)
{
        if (!virt_addr_valid(objp)) {
                printk(KERN_ERR "kfree_debugcheck: out of range ptr %lxh.\n",
                       (unsigned long)objp);
                BUG();
        }
}

static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
{
        unsigned long long redzone1, redzone2;

        redzone1 = *dbg_redzone1(cache, obj);
        redzone2 = *dbg_redzone2(cache, obj);

        /*
         * Redzone is ok.
         */
        if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
                return;

        if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
                slab_error(cache, "double free detected");
        else
                slab_error(cache, "memory outside object was overwritten");

        printk(KERN_ERR "%p: redzone 1:0x%llx, redzone 2:0x%llx.\n",
                        obj, redzone1, redzone2);
}

static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
                                   void *caller)
{
        struct page *page;
        unsigned int objnr;
        struct slab *slabp;

        BUG_ON(virt_to_cache(objp) != cachep);

        objp -= obj_offset(cachep);
        kfree_debugcheck(objp);
        page = virt_to_head_page(objp);

        slabp = page_get_slab(page);

        if (cachep->flags & SLAB_RED_ZONE) {
                verify_redzone_free(cachep, objp);
                *dbg_redzone1(cachep, objp) = RED_INACTIVE;
                *dbg_redzone2(cachep, objp) = RED_INACTIVE;
        }
        if (cachep->flags & SLAB_STORE_USER)
                *dbg_userword(cachep, objp) = caller;

        objnr = obj_to_index(cachep, slabp, objp);

        BUG_ON(objnr >= cachep->num);
        BUG_ON(objp != index_to_obj(cachep, slabp, objnr));

#ifdef CONFIG_DEBUG_SLAB_LEAK
        slab_bufctl(slabp)[objnr] = BUFCTL_FREE;
#endif
        if (cachep->flags & SLAB_POISON) {
#ifdef CONFIG_DEBUG_PAGEALLOC
                if ((cachep->buffer_size % PAGE_SIZE)==0 && OFF_SLAB(cachep)) {
                        store_stackinfo(cachep, objp, (unsigned long)caller);
                        kernel_map_pages(virt_to_page(objp),
                                         cachep->buffer_size / PAGE_SIZE, 0);
                } else {
                        poison_obj(cachep, objp, POISON_FREE);
                }
#else
                poison_obj(cachep, objp, POISON_FREE);
#endif
        }
        return objp;
}

static void check_slabp(struct kmem_cache *cachep, struct slab *slabp)
{
        kmem_bufctl_t i;
        int entries = 0;

        /* Check slab's freelist to see if this obj is there. */
        for (i = slabp->free; i != BUFCTL_END; i = slab_bufctl(slabp)[i]) {
                entries++;
                if (entries > cachep->num || i >= cachep->num)
                        goto bad;
        }
        if (entries != cachep->num - slabp->inuse) {
bad:
                printk(KERN_ERR "slab: Internal list corruption detected in "
                                "cache '%s'(%d), slabp %p(%d). Hexdump:\n",
                        cachep->name, cachep->num, slabp, slabp->inuse);
                for (i = 0;
                     i < sizeof(*slabp) + cachep->num * sizeof(kmem_bufctl_t);
                     i++) {
                        if (i % 16 == 0)
                                printk("\n%03x:", i);
                        printk(" %02x", ((unsigned char *)slabp)[i]);
                }
                printk("\n");
                BUG();
        }
}
#else
#define kfree_debugcheck(x) do { } while(0)
#define cache_free_debugcheck(x,objp,z) (objp)
#define check_slabp(x,y) do { } while(0)
#endif

static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
{
        int batchcount;
        struct kmem_list3 *l3;
        struct array_cache *ac;
        int node;

retry:
        check_irq_off();
        node = numa_node_id();
        ac = cpu_cache_get(cachep);
        batchcount = ac->batchcount;
        if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
                /*
                 * If there was little recent activity on this cache, then
                 * perform only a partial refill.  Otherwise we could generate
                 * refill bouncing.
                 */
                batchcount = BATCHREFILL_LIMIT;
        }
        l3 = cachep->nodelists[node];

        BUG_ON(ac->avail > 0 || !l3);
        spin_lock(&l3->list_lock);

        /* See if we can refill from the shared array */
        if (l3->shared && transfer_objects(ac, l3->shared, batchcount))
                goto alloc_done;

        while (batchcount > 0) {
                struct list_head *entry;
                struct slab *slabp;
                /* Get slab alloc is to come from. */
                entry = l3->slabs_partial.next;
                if (entry == &l3->slabs_partial) {
                        l3->free_touched = 1;
                        entry = l3->slabs_free.next;
                        if (entry == &l3->slabs_free)
                                goto must_grow;
                }