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slab.c

/*
 * 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 intializations 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/config.h>
#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/seq_file.h>
#include    <linux/notifier.h>
#include    <linux/kallsyms.h>
#include    <linux/cpu.h>
#include    <linux/sysctl.h>
#include    <linux/module.h>
#include    <linux/rcupdate.h>
#include    <linux/string.h>
#include    <linux/nodemask.h>
#include    <linux/mempolicy.h>
#include    <linux/mutex.h>
#include    <linux/rtmutex.h>

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

/*
 * DEBUG    - 1 for kmem_cache_create() to honour; SLAB_DEBUG_INITIAL,
 *            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 *)

#ifndef cache_line_size
#define cache_line_size()     L1_CACHE_BYTES
#endif

#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 BYTES_PER_WORD. ARCH_KMALLOC_MINALIGN allows that.
 * Note that this flag disables some debug features.
 */
#define ARCH_KMALLOC_MINALIGN 0
#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_DEBUG_INITIAL | SLAB_RED_ZONE | \
                   SLAB_POISON | SLAB_HWCACHE_ALIGN | \
                   SLAB_CACHE_DMA | \
                   SLAB_MUST_HWCACHE_ALIGN | SLAB_STORE_USER | \
                   SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                   SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD)
#else
# define CREATE_MASK    (SLAB_HWCACHE_ALIGN | \
                   SLAB_CACHE_DMA | SLAB_MUST_HWCACHE_ALIGN | \
                   SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                   SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD)
#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[0];   /*
                   * Must have this definition in here for the proper
                   * alignment of array_cache. Also simplifies accessing
                   * the entries.
                   * [0] is for gcc 2.95. It should really be [].
                   */
};

/*
 * 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 (2 * MAX_NUMNODES + 1)
struct kmem_list3 __initdata initkmem_list3[NUM_INIT_LISTS];
#define     CACHE_CACHE 0
#define     SIZE_AC 1
#define     SIZE_L3 (1 + 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 void enable_cpucache(struct kmem_cache *cachep);
static void cache_reap(void *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;
/* 3) touched by every alloc & free from the backend */
      struct kmem_list3 *nodelists[MAX_NUMNODES];

      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 *, struct kmem_cache *, unsigned long);

      /* de-constructor func */
      void (*dtor) (void *, struct kmem_cache *, unsigned long);

/* 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
};

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

static unsigned 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 *)(objp + cachep->buffer_size -
                               2 * BYTES_PER_WORD);
      return (unsigned long *)(objp + cachep->buffer_size - BYTES_PER_WORD);
}

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 *)NULL;})
#define dbg_redzone2(cachep, objp)  ({BUG(); (unsigned long *)NULL;})
#define dbg_userword(cachep, objp)  ({BUG(); (void **)NULL;})

#endif

/*
 * Maximum size of an obj (in 2^order pages) and absolute limit for the gfp
 * order.
 */
#if defined(CONFIG_LARGE_ALLOCS)
#define     MAX_OBJ_ORDER     13    /* up to 32Mb */
#define     MAX_GFP_ORDER     13    /* up to 32Mb */
#elif defined(CONFIG_MMU)
#define     MAX_OBJ_ORDER     5     /* 32 pages */
#define     MAX_GFP_ORDER     5     /* 32 pages */
#else
#define     MAX_OBJ_ORDER     8     /* up to 1Mb */
#define     MAX_GFP_ORDER     8     /* up to 1Mb */
#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)
{
      if (unlikely(PageCompound(page)))
            page = (struct page *)page_private(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)
{
      if (unlikely(PageCompound(page)))
            page = (struct page *)page_private(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_page(obj);
      return page_get_cache(page);
}

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

static inline unsigned int obj_to_index(struct kmem_cache *cache,
                              struct slab *slab, void *obj)
{
      return (unsigned)(obj - slab->s_mem) / cache->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",
#if DEBUG
      .obj_size = sizeof(struct kmem_cache),
#endif
};

#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.
 */
static struct lock_class_key on_slab_key;

static inline void init_lock_keys(struct cache_sizes *s)
{
      int q;

      for (q = 0; q < MAX_NUMNODES; q++) {
            if (!s->cs_cachep->nodelists[q] || OFF_SLAB(s->cs_cachep))
                  continue;
            lockdep_set_class(&s->cs_cachep->nodelists[q]->list_lock,
                          &on_slab_key);
      }
}

#else
static inline void init_lock_keys(struct cache_sizes *s)
{
}
#endif



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

/*
 * vm_enough_memory() looks at this to determine how many slab-allocated pages
 * are possibly freeable under pressure
 *
 * SLAB_RECLAIM_ACCOUNT turns this on per-slab
 */
atomic_t slab_reclaim_pages;

/*
 * 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 work_struct, 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
      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.
       */
      if (unlikely(gfpflags & GFP_DMA))
            return csizep->cs_dmacachep;
      return csizep->cs_cachep;
}

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

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(__FUNCTION__, 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();
}

#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);

      __get_cpu_var(reap_node) = node;
}

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

      /*
       * Also drain per cpu pages on remote zones
       */
      if (node != numa_node_id())
            drain_node_pages(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 __devinit start_cpu_timer(int cpu)
{
      struct work_struct *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->func == NULL) {
            init_reap_node(cpu);
            INIT_WORK(reap_work, cache_reap, NULL);
            schedule_delayed_work_on(cpu, reap_work, HZ + 3 * 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;
}

#ifdef 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 *) * MAX_NUMNODES;
      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;

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

      l3 = cachep->nodelists[numa_node_id()];
      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;
}

#else

#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 **) 0x01020304ul;
}

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;
}

#endif

static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                            unsigned long action, void *hcpu)
{
      long cpu = (long)hcpu;
      struct kmem_cache *cachep;
      struct kmem_list3 *l3 = NULL;
      int node = cpu_to_node(cpu);
      int memsize = sizeof(struct kmem_list3);

      switch (action) {
      case CPU_UP_PREPARE:
            mutex_lock(&cache_chain_mutex);
            /*
             * 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;
                  struct array_cache **alien;

                  nc = alloc_arraycache(node, cachep->limit,
                                    cachep->batchcount);
                  if (!nc)
                        goto bad;
                  shared = alloc_arraycache(node,
                              cachep->shared * cachep->batchcount,
                              0xbaadf00d);
                  if (!shared)
                        goto bad;

                  alien = alloc_alien_cache(node, cachep->limit);
                  if (!alien)
                        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);
            }
            mutex_unlock(&cache_chain_mutex);
            break;
      case CPU_ONLINE:
            start_cpu_timer(cpu);
            break;
#ifdef CONFIG_HOTPLUG_CPU
      case CPU_DEAD:
            /*
             * 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 thru */
      case CPU_UP_CANCELED:
            mutex_lock(&cache_chain_mutex);
            list_for_each_entry(cachep, &cache_chain, next) {
                  struct array_cache *nc;
                  struct array_cache *shared;
                  struct array_cache **alien;
                  cpumask_t mask;

                  mask = node_to_cpumask(node);
                  /* 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, l3->shared->entry,
                                 l3->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);
            }
            mutex_unlock(&cache_chain_mutex);
            break;
#endif
      }
      return NOTIFY_OK;
bad:
      mutex_unlock(&cache_chain_mutex);
      return NOTIFY_BAD;
}

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;

      BUG_ON(cachep->nodelists[nodeid] != list);
      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();
}

/*
 * 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;

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

      /*
       * 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.
       */

      /* 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[numa_node_id()] = &initkmem_list3[CACHE_CACHE];

      cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
                              cache_line_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, 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, 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, NULL);
            }
            init_lock_keys(sizes);

            sizes->cs_dmacachep = kmem_cache_create(names->name_dma,
                              sizes->cs_size,
                              ARCH_KMALLOC_MINALIGN,
                              ARCH_KMALLOC_FLAGS|SLAB_CACHE_DMA|
                                    SLAB_PANIC,
                              NULL, NULL);
            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 node;
            /* Replace the static kmem_list3 structures for the boot cpu */
            init_list(&cache_cache, &initkmem_list3[CACHE_CACHE],
                    numa_node_id());

            for_each_online_node(node) {
                  init_list(malloc_sizes[INDEX_AC].cs_cachep,
                          &initkmem_list3[SIZE_AC + node], node);

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

      /* 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)
                  enable_cpucache(cachep);
            mutex_unlock(&cache_chain_mutex);
      }

      /* 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;

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

      nr_pages = (1 << cachep->gfporder);
      if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
            atomic_add(nr_pages, &slab_reclaim_pages);
      add_zone_page_state(page_zone(page), NR_SLAB, 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;

      sub_zone_page_state(page_zone(page), NR_SLAB, 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);
      if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
            atomic_sub(1 << cachep->gfporder, &slab_reclaim_pages);
}

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;
      printk(KERN_ERR "%03x:", offset);
      for (i = 0; i < limit; i++)
            printk(" %02x", (unsigned char)data[offset + i]);
      printk("\n");
}
#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%lx/0x%lx.\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: start=%p, len=%d\n",
                              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
/**
 * slab_destroy_objs - destroy a slab and its objects
 * @cachep: cache pointer being destroyed
 * @slabp: slab pointer being destroyed
 *
 * Call the registered destructor for each object in a slab that is being
 * destroyed.
 */
static void slab_destroy_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 (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");
            }
            if (cachep->dtor && !(cachep->flags & SLAB_POISON))
                  (cachep->dtor) (objp + obj_offset(cachep), cachep, 0);
      }
}
#else
static void slab_destroy_objs(struct kmem_cache *cachep, struct slab *slabp)
{
      if (cachep->dtor) {
            int i;
            for (i = 0; i < cachep->num; i++) {
                  void *objp = index_to_obj(cachep, slabp, i);
                  (cachep->dtor) (objp, cachep, 0);
            }
      }
}
#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_objs(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);
      }
}

/*
 * For setting up all the kmem_list3s for cache whose buffer_size is same as
 * size of kmem_list3.
 */
static void 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;
      }
}

/**
 * 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 <= MAX_GFP_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 void setup_cpu_cache(struct kmem_cache *cachep)
{
      if (g_cpucache_up == FULL) {
            enable_cpucache(cachep);
            return;
      }
      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;
}

/**
 * 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.
 * @dtor: A destructor 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
 * and the @dtor is run before the pages are handed back.
 *
 * @name must be valid until the cache is destroyed. This implies that
 * the module calling this has to destroy the cache before getting unloaded.
 *
 * 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*, struct kmem_cache *, unsigned long),
      void (*dtor)(void*, struct kmem_cache *, unsigned long))
{
      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 > (1 << MAX_OBJ_ORDER) * PAGE_SIZE) || (dtor && !ctor)) {
            printk(KERN_ERR "%s: Early error in slab %s\n", __FUNCTION__,
                        name);
            BUG();
      }

      /*
       * Prevent CPUs from coming and going.
       * lock_cpu_hotplug() nests outside cache_chain_mutex
       */
      lock_cpu_hotplug();

      mutex_lock(&cache_chain_mutex);

      list_for_each_entry(pc, &cache_chain, next) {
            mm_segment_t old_fs = get_fs();
            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.
             */
            set_fs(KERNEL_DS);
            res = __get_user(tmp, pc->name);
            set_fs(old_fs);
            if (res) {
                  printk("SLAB: cache with size %d has lost its name\n",
                         pc->buffer_size);
                  continue;
            }

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

#if DEBUG
      WARN_ON(strchr(name, ' '));   /* It confuses parsers */
      if ((flags & SLAB_DEBUG_INITIAL) && !ctor) {
            /* No constructor, but inital state check requested */
            printk(KERN_ERR "%s: No con, but init state check "
                   "requested - %s\n", __FUNCTION__, name);
            flags &= ~SLAB_DEBUG_INITIAL;
      }
#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 + 3 * BYTES_PER_WORD))
            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
      if (flags & SLAB_DESTROY_BY_RCU)
            BUG_ON(dtor);

      /*
       * 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;
      }
      /* 2) arch mandated alignment: disables debug if necessary */
      if (ralign < ARCH_SLAB_MINALIGN) {
            ralign = ARCH_SLAB_MINALIGN;
            if (ralign > BYTES_PER_WORD)
                  flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
      }
      /* 3) caller mandated alignment: disables debug if necessary */
      if (ralign < align) {
            ralign = align;
            if (ralign > BYTES_PER_WORD)
                  flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
      }
      /*
       * 4) Store it. Note that the debug code below can reduce
       *    the alignment to BYTES_PER_WORD.
       */
      align = ralign;

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

#if DEBUG
      cachep->obj_size = size;

      if (flags & SLAB_RED_ZONE) {
            /* redzoning only works with word aligned caches */
            align = BYTES_PER_WORD;

            /* add space for red zone words */
            cachep->obj_offset += BYTES_PER_WORD;
            size += 2 * BYTES_PER_WORD;
      }
      if (flags & SLAB_STORE_USER) {
            /* user store requires word alignment and
             * one word storage behind the end of the real
             * object.
             */
            align = BYTES_PER_WORD;
            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("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 (flags & SLAB_CACHE_DMA)
            cachep->gfpflags |= GFP_DMA;
      cachep->buffer_size = size;

      if (flags & CFLGS_OFF_SLAB)
            cachep->slabp_cache = kmem_find_general_cachep(slab_size, 0u);
      cachep->ctor = ctor;
      cachep->dtor = dtor;
      cachep->name = name;


      setup_cpu_cache(cachep);

      /* 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);
      unlock_cpu_hotplug();
      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, 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;
}

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)
{
      BUG_ON(!cachep || in_interrupt());

      return __cache_shrink(cachep);
}
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.
 * Returns 0 on success.
 *
 * 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().
 */
int kmem_cache_destroy(struct kmem_cache *cachep)
{
      int i;
      struct kmem_list3 *l3;

      BUG_ON(!cachep || in_interrupt());

      /* Don't let CPUs to come and go */
      lock_cpu_hotplug();

      /* Find the cache in the chain of caches. */
      mutex_lock(&cache_chain_mutex);
      /*
       * the chain is never empty, cache_cache is never destroyed
       */
      list_del(&cachep->next);
      mutex_unlock(&cache_chain_mutex);

      if (__cache_shrink(cachep)) {
            slab_error(cachep, "Can't free all objects");
            mutex_lock(&cache_chain_mutex);
            list_add(&cachep->next, &cache_chain);
            mutex_unlock(&cache_chain_mutex);
            unlock_cpu_hotplug();
            return 1;
      }

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

      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);
      unlock_cpu_hotplug();
      return 0;
}
EXPORT_SYMBOL(kmem_cache_destroy);

/* Get the memory for a slab management obj. */
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;
      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, unsigned long ctor_flags)
{
      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), cachep,
                             ctor_flags);

            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, cachep, ctor_flags);
#endif
            slab_bufctl(slabp)[i] = i + 1;
      }
      slab_bufctl(slabp)[i - 1] = BUFCTL_END;
      slabp->free = 0;
}

static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
{
      if (flags & SLAB_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)
{
      struct slab *slabp;
      void *objp;
      size_t offset;
      gfp_t local_flags;
      unsigned long ctor_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 & ~(SLAB_DMA | SLAB_LEVEL_MASK | SLAB_NO_GROW));
      if (flags & SLAB_NO_GROW)
            return 0;

      ctor_flags = SLAB_CTOR_CONSTRUCTOR;
      local_flags = (flags & SLAB_LEVEL_MASK);
      if (!(local_flags & __GFP_WAIT))
            /*
             * Not allowed to sleep.  Need to tell a constructor about
             * this - it might need to know...
             */
            ctor_flags |= SLAB_CTOR_ATOMIC;

      /* 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'.
       */
      objp = kmem_getpages(cachep, flags, nodeid);
      if (!objp)
            goto failed;

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

      slabp->nodeid = nodeid;
      slab_map_pages(cachep, slabp, objp);

      cache_init_objs(cachep, slabp, ctor_flags);

      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
 * - destructor calls, for caches with POISON+dtor
 */
static void kfree_debugcheck(const void *objp)
{
      struct page *page;

      if (!virt_addr_valid(objp)) {
            printk(KERN_ERR "kfree_debugcheck: out of range ptr %lxh.\n",
                   (unsigned long)objp);
            BUG();
      }
      page = virt_to_page(objp);
      if (!PageSlab(page)) {
            printk(KERN_ERR "kfree_debugcheck: bad ptr %lxh.\n",
                   (unsigned long)objp);
            BUG();
      }
}

static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
{
      unsigned 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%lx, redzone 2:0x%lx.\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;

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

      if (cachep->flags & SLAB_DEBUG_INITIAL) {
            /*
             * Need to call the slab's constructor so the caller can
             * perform a verify of its state (debugging).  Called without
             * the cache-lock held.
             */
            cachep->ctor(objp + obj_offset(cachep),
                       cachep, SLAB_CTOR_CONSTRUCTOR | SLAB_CTOR_VERIFY);
      }
      if (cachep->flags & SLAB_POISON && cachep->dtor) {
            /* we want to cache poison the object,
             * call the destruction callback
             */
            cachep->dtor(objp + obj_offset(cachep), cachep, 0);
      }
#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;

      check_irq_off();
      ac = cpu_cache_get(cachep);
retry:
      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[numa_node_id()];

      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;
            }

            slabp = list_entry(entry, struct slab, list);
            check_slabp(cachep, slabp);
            check_spinlock_acquired(cachep);
            while (slabp->inuse < cachep->num && batchcount--) {
                  STATS_INC_ALLOCED(cachep);
                  STATS_INC_ACTIVE(cachep);
                  STATS_SET_HIGH(cachep);

                  ac->entry[ac->avail++] = slab_get_obj(cachep, slabp,
                                              numa_node_id());
            }
            check_slabp(cachep, slabp);

            /* move slabp to correct slabp list: */
            list_del(&slabp->list);
            if (slabp->free == BUFCTL_END)
                  list_add(&slabp->list, &l3->slabs_full);
            else
                  list_add(&slabp->list, &l3->slabs_partial);
      }

must_grow:
      l3->free_objects -= ac->avail;
alloc_done:
      spin_unlock(&l3->list_lock);

      if (unlikely(!ac->avail)) {
            int x;
            x = cache_grow(cachep, flags, numa_node_id());

            /* cache_grow can reenable interrupts, then ac could change. */
            ac = cpu_cache_get(cachep);
            if (!x && ac->avail == 0)     /* no objects in sight? abort */
                  return NULL;

            if (!ac->avail)         /* objects refilled by interrupt? */
                  goto retry;
      }
      ac->touched = 1;
      return ac->entry[--ac->avail];
}

static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
                                    gfp_t flags)
{
      might_sleep_if(flags & __GFP_WAIT);
#if DEBUG
      kmem_flagcheck(cachep, flags);
#endif
}

#if DEBUG
static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
                        gfp_t flags, void *objp, void *caller)
{
      if (!objp)
            return objp;
      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
            poison_obj(cachep, objp, POISON_INUSE);
      }
      if (cachep->flags & SLAB_STORE_USER)
            *dbg_userword(cachep, objp) = caller;

      if (cachep->flags & SLAB_RED_ZONE) {
            if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
                        *dbg_redzone2(cachep, objp) != RED_INACTIVE) {
                  slab_error(cachep, "double free, or memory outside"
                                    " object was overwritten");
                  printk(KERN_ERR
                        "%p: redzone 1:0x%lx, redzone 2:0x%lx\n",
                        objp, *dbg_redzone1(cachep, objp),
                        *dbg_redzone2(cachep, objp));
            }
            *dbg_redzone1(cachep, objp) = RED_ACTIVE;
            *dbg_redzone2(cachep, objp) = RED_ACTIVE;
      }
#ifdef CONFIG_DEBUG_SLAB_LEAK
      {
            struct slab *slabp;
            unsigned objnr;

            slabp = page_get_slab(virt_to_page(objp));
            objnr = (unsigned)(objp - slabp->s_mem) / cachep->buffer_size;
            slab_bufctl(slabp)[objnr] = BUFCTL_ACTIVE;
      }
#endif
      objp += obj_offset(cachep);
      if (cachep->ctor && cachep->flags & SLAB_POISON) {
            unsigned long ctor_flags = SLAB_CTOR_CONSTRUCTOR;

            if (!(flags & __GFP_WAIT))
                  ctor_flags |= SLAB_CTOR_ATOMIC;

            cachep->ctor(objp, cachep, ctor_flags);
      }
      return objp;
}
#else
#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
#endif

static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
      void *objp;
      struct array_cache *ac;

#ifdef CONFIG_NUMA
      if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
            objp = alternate_node_alloc(cachep, flags);
            if (objp != NULL)
                  return objp;
      }
#endif

      check_irq_off();
      ac = cpu_cache_get(cachep);
      if (likely(ac->avail)) {
            STATS_INC_ALLOCHIT(cachep);
            ac->touched = 1;
            objp = ac->entry[--ac->avail];
      } else {
            STATS_INC_ALLOCMISS(cachep);
            objp = cache_alloc_refill(cachep, flags);
      }
      return objp;
}

static __always_inline void *__cache_alloc(struct kmem_cache *cachep,
                                    gfp_t flags, void *caller)
{
      unsigned long save_flags;
      void *objp;

      cache_alloc_debugcheck_before(cachep, flags);

      local_irq_save(save_flags);
      objp = ____cache_alloc(cachep, flags);
      local_irq_restore(save_flags);
      objp = cache_alloc_debugcheck_after(cachep, flags, objp,
                                  caller);
      prefetchw(objp);
      return objp;
}

#ifdef CONFIG_NUMA
/*
 * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.
 *
 * If we are in_interrupt, then process context, including cpusets and
 * mempolicy, may not apply and should not be used for allocation policy.
 */
static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
{
      int nid_alloc, nid_here;

      if (in_interrupt())
            return NULL;
      nid_alloc = nid_here = numa_node_id();
      if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
            nid_alloc = cpuset_mem_spread_node();
      else if (current->mempolicy)
            nid_alloc = slab_node(current->mempolicy);
      if (nid_alloc != nid_here)
            return __cache_alloc_node(cachep, flags, nid_alloc);
      return NULL;
}

/*
 * A interface to enable slab creation on nodeid
 */
static void *__cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
                        int nodeid)
{
      struct list_head *entry;
      struct slab *slabp;
      struct kmem_list3 *l3;
      void *obj;
      int x;

      l3 = cachep->nodelists[nodeid];
      BUG_ON(!l3);

retry:
      check_irq_off();
      spin_lock(&l3->list_lock);
      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;
      }

      slabp = list_entry(entry, struct slab, list);
      check_spinlock_acquired_node(cachep, nodeid);
      check_slabp(cachep, slabp);

      STATS_INC_NODEALLOCS(cachep);
      STATS_INC_ACTIVE(cachep);
      STATS_SET_HIGH(cachep);

      BUG_ON(slabp->inuse == cachep->num);

      obj = slab_get_obj(cachep, slabp, nodeid);
      check_slabp(cachep, slabp);
      l3->free_objects--;
      /* move slabp to correct slabp list: */
      list_del(&slabp->list);

      if (slabp->free == BUFCTL_END)
            list_add(&slabp->list, &l3->slabs_full);
      else
            list_add(&slabp->list, &l3->slabs_partial);

      spin_unlock(&l3->list_lock);
      goto done;

must_grow:
      spin_unlock(&l3->list_lock);
      x = cache_grow(cachep, flags, nodeid);

      if (!x)
            return NULL;

      goto retry;
done:
      return obj;
}
#endif

/*
 * Caller needs to acquire correct kmem_list's list_lock
 */
static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
                   int node)
{
      int i;
      struct kmem_list3 *l3;

      for (i = 0; i < nr_objects; i++) {
            void *objp = objpp[i];
            struct slab *slabp;

            slabp = virt_to_slab(objp);
            l3 = cachep->nodelists[node];
            list_del(&slabp->list);
            check_spinlock_acquired_node(cachep, node);
            check_slabp(cachep, slabp);
            slab_put_obj(cachep, slabp, objp, node);
            STATS_DEC_ACTIVE(cachep);
            l3->free_objects++;
            check_slabp(cachep, slabp);

            /* fixup slab chains */
            if (slabp->inuse == 0) {
                  if (l3->free_objects > l3->free_limit) {
                        l3->free_objects -= cachep->num;
                        slab_destroy(cachep, slabp);
                  } else {
                        list_add(&slabp->list, &l3->slabs_free);
                  }
            } else {
                  /* Unconditionally move a slab to the end of the
                   * partial list on free - maximum time for the
                   * other objects to be freed, too.
                   */
                  list_add_tail(&slabp->list, &l3->slabs_partial);
            }
      }
}

static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
{
      int batchcount;
      struct kmem_list3 *l3;
      int node = numa_node_id();

      batchcount = ac->batchcount;
#if DEBUG
      BUG_ON(!batchcount || batchcount > ac->avail);
#endif
      check_irq_off();
      l3 = cachep->nodelists[node];
      spin_lock(&l3->list_lock);
      if (l3->shared) {
            struct array_cache *shared_array = l3->shared;
            int max = shared_array->limit - shared_array->avail;
            if (max) {
                  if (batchcount > max)
                        batchcount = max;
                  memcpy(&(shared_array->entry[shared_array->avail]),
                         ac->entry, sizeof(void *) * batchcount);
                  shared_array->avail += batchcount;
                  goto free_done;
            }
      }

      free_block(cachep, ac->entry, batchcount, node);
free_done:
#if STATS
      {
            int i = 0;
            struct list_head *p;

            p = l3->slabs_free.next;
            while (p != &(l3->slabs_free)) {
                  struct slab *slabp;

                  slabp = list_entry(p, struct slab, list);
                  BUG_ON(slabp->inuse);

                  i++;
                  p = p->next;
            }
            STATS_SET_FREEABLE(cachep, i);
      }
#endif
      spin_unlock(&l3->list_lock);
      ac->avail -= batchcount;
      memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
}

/*
 * Release an obj back to its cache. If the obj has a constructed state, it must
 * be in this state _before_ it is released.  Called with disabled ints.
 */
static inline void __cache_free(struct kmem_cache *cachep, void *objp)
{
      struct array_cache *ac = cpu_cache_get(cachep);

      check_irq_off();
      objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));

      if (cache_free_alien(cachep, objp))
            return;

      if (likely(ac->avail < ac->limit)) {
            STATS_INC_FREEHIT(cachep);
            ac->entry[ac->avail++] = objp;
            return;
      } else {
            STATS_INC_FREEMISS(cachep);
            cache_flusharray(cachep, ac);
            ac->entry[ac->avail++] = objp;
      }
}

/**
 * kmem_cache_alloc - Allocate an object
 * @cachep: The cache to allocate from.
 * @flags: See kmalloc().
 *
 * Allocate an object from this cache.  The flags are only relevant
 * if the cache has no available objects.
 */
void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
      return __cache_alloc(cachep, flags, __builtin_return_address(0));
}
EXPORT_SYMBOL(kmem_cache_alloc);

/**
 * kmem_cache_zalloc - Allocate an object. The memory is set to zero.
 * @cache: The cache to allocate from.
 * @flags: See kmalloc().
 *
 * Allocate an object from this cache and set the allocated memory to zero.
 * The flags are only relevant if the cache has no available objects.
 */
void *kmem_cache_zalloc(struct kmem_cache *cache, gfp_t flags)
{
      void *ret = __cache_alloc(cache, flags, __builtin_return_address(0));
      if (ret)
            memset(ret, 0, obj_size(cache));
      return ret;
}
EXPORT_SYMBOL(kmem_cache_zalloc);

/**
 * kmem_ptr_validate - check if an untrusted pointer might
 *    be a slab entry.
 * @cachep: the cache we're checking against
 * @ptr: pointer to validate
 *
 * This verifies that the untrusted pointer looks sane:
 * it is _not_ a guarantee that the pointer is actually
 * part of the slab cache in question, but it at least
 * validates that the pointer can be dereferenced and
 * looks half-way sane.
 *
 * Currently only used for dentry validation.
 */
int fastcall kmem_ptr_validate(struct kmem_cache *cachep, void *ptr)
{
      unsigned long addr = (unsigned long)ptr;
      unsigned long min_addr = PAGE_OFFSET;
      unsigned long align_mask = BYTES_PER_WORD - 1;
      unsigned long size = cachep->buffer_size;
      struct page *page;

      if (unlikely(addr < min_addr))
            goto out;
      if (unlikely(addr > (unsigned long)high_memory - size))
            goto out;
      if (unlikely(addr & align_mask))
            goto out;
      if (unlikely(!kern_addr_valid(addr)))
            goto out;
      if (unlikely(!kern_addr_valid(addr + size - 1)))
            goto out;
      page = virt_to_page(ptr);
      if (unlikely(!PageSlab(page)))
            goto out;
      if (unlikely(page_get_cache(page) != cachep))
            goto out;
      return 1;
out:
      return 0;
}

#ifdef CONFIG_NUMA
/**
 * kmem_cache_alloc_node - Allocate an object on the specified node
 * @cachep: The cache to allocate from.
 * @flags: See kmalloc().
 * @nodeid: node number of the target node.
 *
 * Identical to kmem_cache_alloc, except that this function is slow
 * and can sleep. And it will allocate memory on the given node, which
 * can improve the performance for cpu bound structures.
 * New and improved: it will now make sure that the object gets
 * put on the correct node list so that there is no false sharing.
 */
void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
{
      unsigned long save_flags;
      void *ptr;

      cache_alloc_debugcheck_before(cachep, flags);
      local_irq_save(save_flags);

      if (nodeid == -1 || nodeid == numa_node_id() ||
                  !cachep->nodelists[nodeid])
            ptr = ____cache_alloc(cachep, flags);
      else
            ptr = __cache_alloc_node(cachep, flags, nodeid);
      local_irq_restore(save_flags);

      ptr = cache_alloc_debugcheck_after(cachep, flags, ptr,
                                 __builtin_return_address(0));

      return ptr;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);

void *kmalloc_node(size_t size, gfp_t flags, int node)
{
      struct kmem_cache *cachep;

      cachep = kmem_find_general_cachep(size, flags);
      if (unlikely(cachep == NULL))
            return NULL;
      return kmem_cache_alloc_node(cachep, flags, node);
}
EXPORT_SYMBOL(kmalloc_node);
#endif

/**
 * __do_kmalloc - allocate memory
 * @size: how many bytes of memory are required.
 * @flags: the type of memory to allocate (see kmalloc).
 * @caller: function caller for debug tracking of the caller
 */
static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
                                void *caller)
{
      struct kmem_cache *cachep;

      /* If you want to save a few bytes .text space: replace
       * __ with kmem_.
       * Then kmalloc uses the uninlined functions instead of the inline
       * functions.
       */
      cachep = __find_general_cachep(size, flags);
      if (unlikely(cachep == NULL))
            return NULL;
      return __cache_alloc(cachep, flags, caller);
}


void *__kmalloc(size_t size, gfp_t flags)
{
#ifndef CONFIG_DEBUG_SLAB
      return __do_kmalloc(size, flags, NULL);
#else
      return __do_kmalloc(size, flags, __builtin_return_address(0));
#endif
}
EXPORT_SYMBOL(__kmalloc);

#ifdef CONFIG_DEBUG_SLAB
void *__kmalloc_track_caller(size_t size, gfp_t flags, void *caller)
{
      return __do_kmalloc(size, flags, caller);
}
EXPORT_SYMBOL(__kmalloc_track_caller);
#endif

#ifdef CONFIG_SMP
/**
 * __alloc_percpu - allocate one copy of the object for every present
 * cpu in the system, zeroing them.
 * Objects should be dereferenced using the per_cpu_ptr macro only.
 *
 * @size: how many bytes of memory are required.
 */
void *__alloc_percpu(size_t size)
{
      int i;
      struct percpu_data *pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);

      if (!pdata)
            return NULL;

      /*
       * Cannot use for_each_online_cpu since a cpu may come online
       * and we have no way of figuring out how to fix the array
       * that we have allocated then....
       */
      for_each_possible_cpu(i) {
            int node = cpu_to_node(i);

            if (node_online(node))
                  pdata->ptrs[i] = kmalloc_node(size, GFP_KERNEL, node);
            else
                  pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);

            if (!pdata->ptrs[i])
                  goto unwind_oom;
            memset(pdata->ptrs[i], 0, size);
      }

      /* Catch derefs w/o wrappers */
      return (void *)(~(unsigned long)pdata);

unwind_oom:
      while (--i >= 0) {
            if (!cpu_possible(i))
                  continue;
            kfree(pdata->ptrs[i]);
      }
      kfree(pdata);
      return NULL;
}
EXPORT_SYMBOL(__alloc_percpu);
#endif

/**
 * kmem_cache_free - Deallocate an object
 * @cachep: The cache the allocation was from.
 * @objp: The previously allocated object.
 *
 * Free an object which was previously allocated from this
 * cache.
 */
void kmem_cache_free(struct kmem_cache *cachep, void *objp)
{
      unsigned long flags;

      BUG_ON(virt_to_cache(objp) != cachep);

      local_irq_save(flags);
      __cache_free(cachep, objp);
      local_irq_restore(flags);
}
EXPORT_SYMBOL(kmem_cache_free);

/**
 * kfree - free previously allocated memory
 * @objp: pointer returned by kmalloc.
 *
 * If @objp is NULL, no operation is performed.
 *
 * Don't free memory not originally allocated by kmalloc()
 * or you will run into trouble.
 */
void kfree(const void *objp)
{
      struct kmem_cache *c;
      unsigned long flags;

      if (unlikely(!objp))
            return;
      local_irq_save(flags);
      kfree_debugcheck(objp);
      c = virt_to_cache(objp);
      debug_check_no_locks_freed(objp, obj_size(c));
      __cache_free(c, (void *)objp);
      local_irq_restore(flags);
}
EXPORT_SYMBOL(kfree);

#ifdef CONFIG_SMP
/**
 * free_percpu - free previously allocated percpu memory
 * @objp: pointer returned by alloc_percpu.
 *
 * Don't free memory not originally allocated by alloc_percpu()
 * The complemented objp is to check for that.
 */
void free_percpu(const void *objp)
{
      int i;
      struct percpu_data *p = (struct percpu_data *)(~(unsigned long)objp);

      /*
       * We allocate for all cpus so we cannot use for online cpu here.
       */
      for_each_possible_cpu(i)
          kfree(p->ptrs[i]);
      kfree(p);
}
EXPORT_SYMBOL(free_percpu);
#endif

unsigned int kmem_cache_size(struct kmem_cache *cachep)
{
      return obj_size(cachep);
}
EXPORT_SYMBOL(kmem_cache_size);

const char *kmem_cache_name(struct kmem_cache *cachep)
{
      return cachep->name;
}
EXPORT_SYMBOL_GPL(kmem_cache_name);

/*
 * This initializes kmem_list3 or resizes varioius caches for all nodes.
 */
static int alloc_kmemlist(struct kmem_cache *cachep)
{
      int node;
      struct kmem_list3 *l3;
      struct array_cache *new_shared;
      struct array_cache **new_alien;

      for_each_online_node(node) {

            new_alien = alloc_alien_cache(node, cachep->limit);
            if (!new_alien)
                  goto fail;

            new_shared = alloc_arraycache(node,
                        cachep->shared*cachep->batchcount,
                              0xbaadf00d);
            if (!new_shared) {
                  free_alien_cache(new_alien);
                  goto fail;
            }

            l3 = cachep->nodelists[node];
            if (l3) {
                  struct array_cache *shared = l3->shared;

                  spin_lock_irq(&l3->list_lock);

                  if (shared)
                        free_block(cachep, shared->entry,
                                    shared->avail, node);

                  l3->shared = new_shared;
                  if (!l3->alien) {
                        l3->alien = new_alien;
                        new_alien = NULL;
                  }
                  l3->free_limit = (1 + nr_cpus_node(node)) *
                              cachep->batchcount + cachep->num;
                  spin_unlock_irq(&l3->list_lock);
                  kfree(shared);
                  free_alien_cache(new_alien);
                  continue;
            }
            l3 = kmalloc_node(sizeof(struct kmem_list3), GFP_KERNEL, node);
            if (!l3) {
                  free_alien_cache(new_alien);
                  kfree(new_shared);
                  goto fail;
            }

            kmem_list3_init(l3);
            l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
                        ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
            l3->shared = new_shared;
            l3->alien = new_alien;
            l3->free_limit = (1 + nr_cpus_node(node)) *
                              cachep->batchcount + cachep->num;
            cachep->nodelists[node] = l3;
      }
      return 0;

fail:
      if (!cachep->next.next) {
            /* Cache is not active yet. Roll back what we did */
            node--;
            while (node >= 0) {
                  if (cachep->nodelists[node]) {
                        l3 = cachep->nodelists[node];

                        kfree(l3->shared);
                        free_alien_cache(l3->alien);
                        kfree(l3);
                        cachep->nodelists[node] = NULL;
                  }
                  node--;
            }
      }
      return -ENOMEM;
}

struct ccupdate_struct {
      struct kmem_cache *cachep;
      struct array_cache *new[NR_CPUS];
};

static void do_ccupdate_local(void *info)
{
      struct ccupdate_struct *new = info;
      struct array_cache *old;

      check_irq_off();
      old = cpu_cache_get(new->cachep);

      new->cachep->array[smp_processor_id()] = new->new[smp_processor_id()];
      new->new[smp_processor_id()] = old;
}

/* Always called with the cache_chain_mutex held */
static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
                        int batchcount, int shared)
{
      struct ccupdate_struct new;
      int i, err;

      memset(&new.new, 0, sizeof(new.new));
      for_each_online_cpu(i) {
            new.new[i] = alloc_arraycache(cpu_to_node(i), limit,
                                    batchcount);
            if (!new.new[i]) {
                  for (i--; i >= 0; i--)
                        kfree(new.new[i]);
                  return -ENOMEM;
            }
      }
      new.cachep = cachep;

      on_each_cpu(do_ccupdate_local, (void *)&new, 1, 1);

      check_irq_on();
      cachep->batchcount = batchcount;
      cachep->limit = limit;
      cachep->shared = shared;

      for_each_online_cpu(i) {
            struct array_cache *ccold = new.new[i];
            if (!ccold)
                  continue;
            spin_lock_irq(&cachep->nodelists[cpu_to_node(i)]->list_lock);
            free_block(cachep, ccold->entry, ccold->avail, cpu_to_node(i));
            spin_unlock_irq(&cachep->nodelists[cpu_to_node(i)]->list_lock);
            kfree(ccold);
      }

      err = alloc_kmemlist(cachep);
      if (err) {
            printk(KERN_ERR "alloc_kmemlist failed for %s, error %d.\n",
                   cachep->name, -err);
            BUG();
      }
      return 0;
}

/* Called with cache_chain_mutex held always */
static void enable_cpucache(struct kmem_cache *cachep)
{
      int err;
      int limit, shared;

      /*
       * The head array serves three purposes:
       * - create a LIFO ordering, i.e. return objects that are cache-warm
       * - reduce the number of spinlock operations.
       * - reduce the number of linked list operations on the slab and
       *   bufctl chains: array operations are cheaper.
       * The numbers are guessed, we should auto-tune as described by
       * Bonwick.
       */
      if (cachep->buffer_size > 131072)
            limit = 1;
      else if (cachep->buffer_size > PAGE_SIZE)
            limit = 8;
      else if (cachep->buffer_size > 1024)
            limit = 24;
      else if (cachep->buffer_size > 256)
            limit = 54;
      else
            limit = 120;

      /*
       * CPU bound tasks (e.g. network routing) can exhibit cpu bound
       * allocation behaviour: Most allocs on one cpu, most free operations
       * on another cpu. For these cases, an efficient object passing between
       * cpus is necessary. This is provided by a shared array. The array
       * replaces Bonwick's magazine layer.
       * On uniprocessor, it's functionally equivalent (but less efficient)
       * to a larger limit. Thus disabled by default.
       */
      shared = 0;
#ifdef CONFIG_SMP
      if (cachep->buffer_size <= PAGE_SIZE)
            shared = 8;
#endif

#if DEBUG
      /*
       * With debugging enabled, large batchcount lead to excessively long
       * periods with disabled local interrupts. Limit the batchcount
       */
      if (limit > 32)
            limit = 32;
#endif
      err = do_tune_cpucache(cachep, limit, (limit + 1) / 2, shared);
      if (err)
            printk(KERN_ERR "enable_cpucache failed for %s, error %d.\n",
                   cachep->name, -err);
}

/*
 * Drain an array if it contains any elements taking the l3 lock only if
 * necessary. Note that the l3 listlock also protects the array_cache
 * if drain_array() is used on the shared array.
 */
void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
                   struct array_cache *ac, int force, int node)
{
      int tofree;

      if (!ac || !ac->avail)
            return;
      if (ac->touched && !force) {
            ac->touched = 0;
      } else {
            spin_lock_irq(&l3->list_lock);
            if (ac->avail) {
                  tofree = force ? ac->avail : (ac->limit + 4) / 5;
                  if (tofree > ac->avail)
                        tofree = (ac->avail + 1) / 2;
                  free_block(cachep, ac->entry, tofree, node);
                  ac->avail -= tofree;
                  memmove(ac->entry, &(ac->entry[tofree]),
                        sizeof(void *) * ac->avail);
            }
            spin_unlock_irq(&l3->list_lock);
      }
}

/**
 * cache_reap - Reclaim memory from caches.
 * @unused: unused parameter
 *
 * Called from workqueue/eventd every few seconds.
 * Purpose:
 * - clear the per-cpu caches for this CPU.
 * - return freeable pages to the main free memory pool.
 *
 * If we cannot acquire the cache chain mutex then just give up - we'll try
 * again on the next iteration.
 */
static void cache_reap(void *unused)
{
      struct kmem_cache *searchp;
      struct kmem_list3 *l3;
      int node = numa_node_id();

      if (!mutex_trylock(&cache_chain_mutex)) {
            /* Give up. Setup the next iteration. */
            schedule_delayed_work(&__get_cpu_var(reap_work),
                              REAPTIMEOUT_CPUC);
            return;
      }

      list_for_each_entry(searchp, &cache_chain, next) {
            check_irq_on();

            /*
             * We only take the l3 lock if absolutely necessary and we
             * have established with reasonable certainty that
             * we can do some work if the lock was obtained.
             */
            l3 = searchp->nodelists[node];

            reap_alien(searchp, l3);

            drain_array(searchp, l3, cpu_cache_get(searchp), 0, node);

            /*
             * These are racy checks but it does not matter
             * if we skip one check or scan twice.
             */
            if (time_after(l3->next_reap, jiffies))
                  goto next;

            l3->next_reap = jiffies + REAPTIMEOUT_LIST3;

            drain_array(searchp, l3, l3->shared, 0, node);

            if (l3->free_touched)
                  l3->free_touched = 0;
            else {
                  int freed;

                  freed = drain_freelist(searchp, l3, (l3->free_limit +
                        5 * searchp->num - 1) / (5 * searchp->num));
                  STATS_ADD_REAPED(searchp, freed);
            }
next:
            cond_resched();
      }
      check_irq_on();
      mutex_unlock(&cache_chain_mutex);
      next_reap_node();
      refresh_cpu_vm_stats(smp_processor_id());
      /* Set up the next iteration */
      schedule_delayed_work(&__get_cpu_var(reap_work), REAPTIMEOUT_CPUC);
}

#ifdef CONFIG_PROC_FS

static void print_slabinfo_header(struct seq_file *m)
{
      /*
       * Output format version, so at least we can change it
       * without _too_ many complaints.
       */
#if STATS
      seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
#else
      seq_puts(m, "slabinfo - version: 2.1\n");
#endif
      seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
             "<objperslab> <pagesperslab>");
      seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
      seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
#if STATS
      seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
             "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
      seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
#endif
      seq_putc(m, '\n');
}

static void *s_start(struct seq_file *m, loff_t *pos)
{
      loff_t n = *pos;
      struct list_head *p;

      mutex_lock(&cache_chain_mutex);
      if (!n)
            print_slabinfo_header(m);
      p = cache_chain.next;
      while (n--) {
            p = p->next;
            if (p == &cache_chain)
                  return NULL;
      }
      return list_entry(p, struct kmem_cache, next);
}

static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
      struct kmem_cache *cachep = p;
      ++*pos;
      return cachep->next.next == &cache_chain ?
            NULL : list_entry(cachep->next.next, struct kmem_cache, next);
}

static void s_stop(struct seq_file *m, void *p)
{
      mutex_unlock(&cache_chain_mutex);
}

static int s_show(struct seq_file *m, void *p)
{
      struct kmem_cache *cachep = p;
      struct slab *slabp;
      unsigned long active_objs;
      unsigned long num_objs;
      unsigned long active_slabs = 0;
      unsigned long num_slabs, free_objects = 0, shared_avail = 0;
      const char *name;
      char *error = NULL;
      int node;
      struct kmem_list3 *l3;

      active_objs = 0;
      num_slabs = 0;
      for_each_online_node(node) {
            l3 = cachep->nodelists[node];
            if (!l3)
                  continue;

            check_irq_on();
            spin_lock_irq(&l3->list_lock);

            list_for_each_entry(slabp, &l3->slabs_full, list) {
                  if (slabp->inuse != cachep->num && !error)
                        error = "slabs_full accounting error";
                  active_objs += cachep->num;
                  active_slabs++;
            }
            list_for_each_entry(slabp, &l3->slabs_partial, list) {
                  if (slabp->inuse == cachep->num && !error)
                        error = "slabs_partial inuse accounting error";
                  if (!slabp->inuse && !error)
                        error = "slabs_partial/inuse accounting error";
                  active_objs += slabp->inuse;
                  active_slabs++;
            }
            list_for_each_entry(slabp, &l3->slabs_free, list) {
                  if (slabp->inuse && !error)
                        error = "slabs_free/inuse accounting error";
                  num_slabs++;
            }
            free_objects += l3->free_objects;
            if (l3->shared)
                  shared_avail += l3->shared->avail;

            spin_unlock_irq(&l3->list_lock);
      }
      num_slabs += active_slabs;
      num_objs = num_slabs * cachep->num;
      if (num_objs - active_objs != free_objects && !error)
            error = "free_objects accounting error";

      name = cachep->name;
      if (error)
            printk(KERN_ERR "slab: cache %s error: %s\n", name, error);

      seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
               name, active_objs, num_objs, cachep->buffer_size,
               cachep->num, (1 << cachep->gfporder));
      seq_printf(m, " : tunables %4u %4u %4u",
               cachep->limit, cachep->batchcount, cachep->shared);
      seq_printf(m, " : slabdata %6lu %6lu %6lu",
               active_slabs, num_slabs, shared_avail);
#if STATS
      {                 /* list3 stats */
            unsigned long high = cachep->high_mark;
            unsigned long allocs = cachep->num_allocations;
            unsigned long grown = cachep->grown;
            unsigned long reaped = cachep->reaped;
            unsigned long errors = cachep->errors;
            unsigned long max_freeable = cachep->max_freeable;
            unsigned long node_allocs = cachep->node_allocs;
            unsigned long node_frees = cachep->node_frees;
            unsigned long overflows = cachep->node_overflow;

            seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu \
                        %4lu %4lu %4lu %4lu %4lu", allocs, high, grown,
                        reaped, errors, max_freeable, node_allocs,
                        node_frees, overflows);
      }
      /* cpu stats */
      {
            unsigned long allochit = atomic_read(&cachep->allochit);
            unsigned long allocmiss = atomic_read(&cachep->allocmiss);
            unsigned long freehit = atomic_read(&cachep->freehit);
            unsigned long freemiss = atomic_read(&cachep->freemiss);

            seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
                     allochit, allocmiss, freehit, freemiss);
      }
#endif
      seq_putc(m, '\n');
      return 0;
}

/*
 * slabinfo_op - iterator that generates /proc/slabinfo
 *
 * Output layout:
 * cache-name
 * num-active-objs
 * total-objs
 * object size
 * num-active-slabs
 * total-slabs
 * num-pages-per-slab
 * + further values on SMP and with statistics enabled
 */

struct seq_operations slabinfo_op = {
      .start = s_start,
      .next = s_next,
      .stop = s_stop,
      .show = s_show,
};

#define MAX_SLABINFO_WRITE 128
/**
 * slabinfo_write - Tuning for the slab allocator
 * @file: unused
 * @buffer: user buffer
 * @count: data length
 * @ppos: unused
 */
ssize_t slabinfo_write(struct file *file, const char __user * buffer,
                   size_t count, loff_t *ppos)
{
      char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
      int limit, batchcount, shared, res;
      struct kmem_cache *cachep;

      if (count > MAX_SLABINFO_WRITE)
            return -EINVAL;
      if (copy_from_user(&kbuf, buffer, count))
            return -EFAULT;
      kbuf[MAX_SLABINFO_WRITE] = '\0';

      tmp = strchr(kbuf, ' ');
      if (!tmp)
            return -EINVAL;
      *tmp = '\0';
      tmp++;
      if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
            return -EINVAL;

      /* Find the cache in the chain of caches. */
      mutex_lock(&cache_chain_mutex);
      res = -EINVAL;
      list_for_each_entry(cachep, &cache_chain, next) {
            if (!strcmp(cachep->name, kbuf)) {
                  if (limit < 1 || batchcount < 1 ||
                              batchcount > limit || shared < 0) {
                        res = 0;
                  } else {
                        res = do_tune_cpucache(cachep, limit,
                                           batchcount, shared);
                  }
                  break;
            }
      }
      mutex_unlock(&cache_chain_mutex);
      if (res >= 0)
            res = count;
      return res;
}

#ifdef CONFIG_DEBUG_SLAB_LEAK

static void *leaks_start(struct seq_file *m, loff_t *pos)
{
      loff_t n = *pos;
      struct list_head *p;

      mutex_lock(&cache_chain_mutex);
      p = cache_chain.next;
      while (n--) {
            p = p->next;
            if (p == &cache_chain)
                  return NULL;
      }
      return list_entry(p, struct kmem_cache, next);
}

static inline int add_caller(unsigned long *n, unsigned long v)
{
      unsigned long *p;
      int l;
      if (!v)
            return 1;
      l = n[1];
      p = n + 2;
      while (l) {
            int i = l/2;
            unsigned long *q = p + 2 * i;
            if (*q == v) {
                  q[1]++;
                  return 1;
            }
            if (*q > v) {
                  l = i;
            } else {
                  p = q + 2;
                  l -= i + 1;
            }
      }
      if (++n[1] == n[0])
            return 0;
      memmove(p + 2, p, n[1] * 2 * sizeof(unsigned long) - ((void *)p - (void *)n));
      p[0] = v;
      p[1] = 1;
      return 1;
}

static void handle_slab(unsigned long *n, struct kmem_cache *c, struct slab *s)
{
      void *p;
      int i;
      if (n[0] == n[1])
            return;
      for (i = 0, p = s->s_mem; i < c->num; i++, p += c->buffer_size) {
            if (slab_bufctl(s)[i] != BUFCTL_ACTIVE)
                  continue;
            if (!add_caller(n, (unsigned long)*dbg_userword(c, p)))
                  return;
      }
}

static void show_symbol(struct seq_file *m, unsigned long address)
{
#ifdef CONFIG_KALLSYMS
      char *modname;
      const char *name;
      unsigned long offset, size;
      char namebuf[KSYM_NAME_LEN+1];

      name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);

      if (name) {
            seq_printf(m, "%s+%#lx/%#lx", name, offset, size);
            if (modname)
                  seq_printf(m, " [%s]", modname);
            return;
      }
#endif
      seq_printf(m, "%p", (void *)address);
}

static int leaks_show(struct seq_file *m, void *p)
{
      struct kmem_cache *cachep = p;
      struct slab *slabp;
      struct kmem_list3 *l3;
      const char *name;
      unsigned long *n = m->private;
      int node;
      int i;

      if (!(cachep->flags & SLAB_STORE_USER))
            return 0;
      if (!(cachep->flags & SLAB_RED_ZONE))
            return 0;

      /* OK, we can do it */

      n[1] = 0;

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

            check_irq_on();
            spin_lock_irq(&l3->list_lock);

            list_for_each_entry(slabp, &l3->slabs_full, list)
                  handle_slab(n, cachep, slabp);
            list_for_each_entry(slabp, &l3->slabs_partial, list)
                  handle_slab(n, cachep, slabp);
            spin_unlock_irq(&l3->list_lock);
      }
      name = cachep->name;
      if (n[0] == n[1]) {
            /* Increase the buffer size */
            mutex_unlock(&cache_chain_mutex);
            m->private = kzalloc(n[0] * 4 * sizeof(unsigned long), GFP_KERNEL);
            if (!m->private) {
                  /* Too bad, we are really out */
                  m->private = n;
                  mutex_lock(&cache_chain_mutex);
                  return -ENOMEM;
            }
            *(unsigned long *)m->private = n[0] * 2;
            kfree(n);
            mutex_lock(&cache_chain_mutex);
            /* Now make sure this entry will be retried */
            m->count = m->size;
            return 0;
      }
      for (i = 0; i < n[1]; i++) {
            seq_printf(m, "%s: %lu ", name, n[2*i+3]);
            show_symbol(m, n[2*i+2]);
            seq_putc(m, '\n');
      }
      return 0;
}

struct seq_operations slabstats_op = {
      .start = leaks_start,
      .next = s_next,
      .stop = s_stop,
      .show = leaks_show,
};
#endif
#endif

/**
 * ksize - get the actual amount of memory allocated for a given object
 * @objp: Pointer to the object
 *
 * kmalloc may internally round up allocations and return more memory
 * than requested. ksize() can be used to determine the actual amount of
 * memory allocated. The caller may use this additional memory, even though
 * a smaller amount of memory was initially specified with the kmalloc call.
 * The caller must guarantee that objp points to a valid object previously
 * allocated with either kmalloc() or kmem_cache_alloc(). The object
 * must not be freed during the duration of the call.
 */
unsigned int ksize(const void *objp)
{
      if (unlikely(objp == NULL))
            return 0;

      return obj_size(virt_to_cache(objp));
}

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