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Version: 2.6.8   2.6.16   2.6.25   2.6.30   2.6.34  

Architecture: i386   arm   mips   ppc   alpha   m68k   sparc   sparc64  

   /*
    * 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 kmem_cache_t 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 semaphore 'cache_chain_sem'.
   *      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.
   *
   */
  
  #include        <linux/config.h>
  #include        <linux/slab.h>
  #include        <linux/mm.h>
  #include        <linux/swap.h>
  #include        <linux/cache.h>
  #include        <linux/interrupt.h>
  #include        <linux/init.h>
  #include        <linux/compiler.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        <asm/uaccess.h>
  #include        <asm/cacheflush.h>
  #include        <asm/tlbflush.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
 #define ARCH_KMALLOC_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_NO_REAP | SLAB_CACHE_DMA | \
                          SLAB_MUST_HWCACHE_ALIGN | SLAB_STORE_USER | \
                          SLAB_RECLAIM_ACCOUNT | SLAB_PANIC)
 #else
 # define CREATE_MASK    (SLAB_HWCACHE_ALIGN | SLAB_NO_REAP | \
                          SLAB_CACHE_DMA | SLAB_MUST_HWCACHE_ALIGN | \
                          SLAB_RECLAIM_ACCOUNT | SLAB_PANIC)
 #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.
  */
 
 #define BUFCTL_END      (((kmem_bufctl_t)(~0U))-0)
 #define BUFCTL_FREE     (((kmem_bufctl_t)(~0U))-1)
 #define SLAB_LIMIT      (((kmem_bufctl_t)(~0U))-2)
 
 /* Max number of objs-per-slab for caches which use off-slab slabs.
  * Needed to avoid a possible looping condition in cache_grow().
  */
 static unsigned long offslab_limit;
 
 /*
  * 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;
 };
 
 /*
  * struct array_cache
  *
  * Per cpu structures
  * 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;
 };
 
 /* 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 of all objects.
  * Hopefully reduce the internal fragmentation
  * NUMA: The spinlock could be moved from the kmem_cache_t
  * into this structure, too. Figure out what causes
  * fewer cross-node spinlock operations.
  */
 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;
         int             free_touched;
         unsigned long   next_reap;
         struct array_cache      *shared;
 };
 
 #define LIST3_INIT(parent) \
         { \
                 .slabs_full     = LIST_HEAD_INIT(parent.slabs_full), \
                 .slabs_partial  = LIST_HEAD_INIT(parent.slabs_partial), \
                 .slabs_free     = LIST_HEAD_INIT(parent.slabs_free) \
         }
 #define list3_data(cachep) \
         (&(cachep)->lists)
 
 /* NUMA: per-node */
 #define list3_data_ptr(cachep, ptr) \
                 list3_data(cachep)
 
 /*
  * kmem_cache_t
  *
  * manages a cache.
  */
         
 struct kmem_cache_s {
 /* 1) per-cpu data, touched during every alloc/free */
         struct array_cache      *array[NR_CPUS];
         unsigned int            batchcount;
         unsigned int            limit;
 /* 2) touched by every alloc & free from the backend */
         struct kmem_list3       lists;
         /* NUMA: kmem_3list_t   *nodelists[MAX_NUMNODES] */
         unsigned int            objsize;
         unsigned int            flags;  /* constant flags */
         unsigned int            num;    /* # of objs per slab */
         unsigned int            free_limit; /* upper limit of objects in the lists */
         spinlock_t              spinlock;
 
 /* 3) cache_grow/shrink */
         /* order of pgs per slab (2^n) */
         unsigned int            gfporder;
 
         /* force GFP flags, e.g. GFP_DMA */
         unsigned int            gfpflags;
 
         size_t                  colour;         /* cache colouring range */
         unsigned int            colour_off;     /* colour offset */
         unsigned int            colour_next;    /* cache colouring */
         kmem_cache_t            *slabp_cache;
         unsigned int            slab_size;
         unsigned int            dflags;         /* dynamic flags */
 
         /* constructor func */
         void (*ctor)(void *, kmem_cache_t *, unsigned long);
 
         /* de-constructor func */
         void (*dtor)(void *, kmem_cache_t *, unsigned long);
 
 /* 4) cache creation/removal */
         const char              *name;
         struct list_head        next;
 
 /* 5) 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;
         atomic_t                allochit;
         atomic_t                allocmiss;
         atomic_t                freehit;
         atomic_t                freemiss;
 #endif
 #if DEBUG
         int                     dbghead;
         int                     reallen;
 #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.
  *
  * OTHO 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_INC_REAPED(x)     ((x)->reaped++)
 #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_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_INC_REAPED(x)     do { } while (0)
 #define STATS_SET_HIGH(x)       do { } while (0)
 #define STATS_INC_ERR(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
 /* Magic nums for obj red zoning.
  * Placed in the first word before and the first word after an obj.
  */
 #define RED_INACTIVE    0x5A2CF071UL    /* when obj is inactive */
 #define RED_ACTIVE      0x170FC2A5UL    /* when obj is active */
 
 /* ...and for poisoning */
 #define POISON_INUSE    0x5a    /* for use-uninitialised poisoning */
 #define POISON_FREE     0x6b    /* for use-after-free poisoning */
 #define POISON_END      0xa5    /* end-byte of poisoning */
 
 /* memory layout of objects:
  * 0            : objp
  * 0 .. cachep->dbghead - 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->dbghead - BYTES_PER_WORD .. cachep->dbghead - 1:
  *              redzone word.
  * cachep->dbghead: The real object.
  * cachep->objsize - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
  * cachep->objsize - 1* BYTES_PER_WORD: last caller address [BYTES_PER_WORD long]
  */
 static int obj_dbghead(kmem_cache_t *cachep)
 {
         return cachep->dbghead;
 }
 
 static int obj_reallen(kmem_cache_t *cachep)
 {
         return cachep->reallen;
 }
 
 static unsigned long *dbg_redzone1(kmem_cache_t *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
         return (unsigned long*) (objp+obj_dbghead(cachep)-BYTES_PER_WORD);
 }
 
 static unsigned long *dbg_redzone2(kmem_cache_t *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
         if (cachep->flags & SLAB_STORE_USER)
                 return (unsigned long*) (objp+cachep->objsize-2*BYTES_PER_WORD);
         return (unsigned long*) (objp+cachep->objsize-BYTES_PER_WORD);
 }
 
 static void **dbg_userword(kmem_cache_t *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_STORE_USER));
         return (void**)(objp+cachep->objsize-BYTES_PER_WORD);
 }
 
 #else
 
 #define obj_dbghead(x)                  0
 #define obj_reallen(cachep)             (cachep->objsize)
 #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;
 
 /* Macros for storing/retrieving the cachep and or slab from the
  * global 'mem_map'. 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.
  */
 #define SET_PAGE_CACHE(pg,x)  ((pg)->lru.next = (struct list_head *)(x))
 #define GET_PAGE_CACHE(pg)    ((kmem_cache_t *)(pg)->lru.next)
 #define SET_PAGE_SLAB(pg,x)   ((pg)->lru.prev = (struct list_head *)(x))
 #define GET_PAGE_SLAB(pg)     ((struct slab *)(pg)->lru.prev)
 
 /* 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>
         { 0, }
 #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
 };
 
 struct arraycache_init initarray_cache __initdata = { { 0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
 struct arraycache_init initarray_generic __initdata = { { 0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
 
 /* internal cache of cache description objs */
 static kmem_cache_t cache_cache = {
         .lists          = LIST3_INIT(cache_cache.lists),
         .batchcount     = 1,
         .limit          = BOOT_CPUCACHE_ENTRIES,
         .objsize        = sizeof(kmem_cache_t),
         .flags          = SLAB_NO_REAP,
         .spinlock       = SPIN_LOCK_UNLOCKED,
         .name           = "kmem_cache",
 #if DEBUG
         .reallen        = sizeof(kmem_cache_t),
 #endif
 };
 
 /* Guard access to the cache-chain. */
 static struct semaphore cache_chain_sem;
 
 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;
 EXPORT_SYMBOL(slab_reclaim_pages);
 
 /*
  * chicken and egg problem: delay the per-cpu array allocation
  * until the general caches are up.
  */
 enum {
         NONE,
         PARTIAL,
         FULL
 } g_cpucache_up;
 
 static DEFINE_PER_CPU(struct timer_list, reap_timers);
 
 static void reap_timer_fnc(unsigned long data);
 static void free_block(kmem_cache_t* cachep, void** objpp, int len);
 static void enable_cpucache (kmem_cache_t *cachep);
 
 static inline void ** ac_entry(struct array_cache *ac)
 {
         return (void**)(ac+1);
 }
 
 static inline struct array_cache *ac_data(kmem_cache_t *cachep)
 {
         return cachep->array[smp_processor_id()];
 }
 
 /* Cal the num objs, wastage, and bytes left over for a given slab size. */
 static void cache_estimate (unsigned long gfporder, size_t size, size_t align,
                  int flags, size_t *left_over, unsigned int *num)
 {
         int i;
         size_t wastage = PAGE_SIZE<<gfporder;
         size_t extra = 0;
         size_t base = 0;
 
         if (!(flags & CFLGS_OFF_SLAB)) {
                 base = sizeof(struct slab);
                 extra = sizeof(kmem_bufctl_t);
         }
         i = 0;
         while (i*size + ALIGN(base+i*extra, align) <= wastage)
                 i++;
         if (i > 0)
                 i--;
 
         if (i > SLAB_LIMIT)
                 i = SLAB_LIMIT;
 
         *num = i;
         wastage -= i*size;
         wastage -= ALIGN(base+i*extra, align);
         *left_over = wastage;
 }
 
 #define slab_error(cachep, msg) __slab_error(__FUNCTION__, cachep, msg)
 
 static void __slab_error(const char *function, kmem_cache_t *cachep, char *msg)
 {
         printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
                 function, cachep->name, msg);
         dump_stack();
 }
 
 /*
  * Start the reap timer running on the target CPU.  We run at around 1 to 2Hz.
  * Add the CPU number into the expiry 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 timer_list *rt = &per_cpu(reap_timers, cpu);
 
         if (rt->function == NULL) {
                 init_timer(rt);
                 rt->expires = jiffies + HZ + 3*cpu;
                 rt->data = cpu;
                 rt->function = reap_timer_fnc;
                 add_timer_on(rt, cpu);
         }
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
 static void stop_cpu_timer(int cpu)
 {
         struct timer_list *rt = &per_cpu(reap_timers, cpu);
 
         if (rt->function) {
                 del_timer_sync(rt);
                 WARN_ON(timer_pending(rt));
                 rt->function = NULL;
         }
 }
 #endif
 
 static struct array_cache *alloc_arraycache(int cpu, int entries, int batchcount)
 {
         int memsize = sizeof(void*)*entries+sizeof(struct array_cache);
         struct array_cache *nc = NULL;
 
         if (cpu != -1) {
                 nc = kmem_cache_alloc_node(kmem_find_general_cachep(memsize,
                                         GFP_KERNEL), cpu_to_node(cpu));
         }
         if (!nc)
                 nc = kmalloc(memsize, GFP_KERNEL);
         if (nc) {
                 nc->avail = 0;
                 nc->limit = entries;
                 nc->batchcount = batchcount;
                 nc->touched = 0;
         }
         return nc;
 }
 
 static int __devinit cpuup_callback(struct notifier_block *nfb,
                                   unsigned long action,
                                   void *hcpu)
 {
         long cpu = (long)hcpu;
         kmem_cache_t* cachep;
 
         switch (action) {
         case CPU_UP_PREPARE:
                 down(&cache_chain_sem);
                 list_for_each_entry(cachep, &cache_chain, next) {
                         struct array_cache *nc;
 
                         nc = alloc_arraycache(cpu, cachep->limit, cachep->batchcount);
                         if (!nc)
                                 goto bad;
 
                         spin_lock_irq(&cachep->spinlock);
                         cachep->array[cpu] = nc;
                         cachep->free_limit = (1+num_online_cpus())*cachep->batchcount
                                                 + cachep->num;
                         spin_unlock_irq(&cachep->spinlock);
 
                 }
                 up(&cache_chain_sem);
                 break;
         case CPU_ONLINE:
                 start_cpu_timer(cpu);
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
         case CPU_DEAD:
                 stop_cpu_timer(cpu);
                 /* fall thru */
         case CPU_UP_CANCELED:
                 down(&cache_chain_sem);
 
                 list_for_each_entry(cachep, &cache_chain, next) {
                         struct array_cache *nc;
 
                         spin_lock_irq(&cachep->spinlock);
                         /* cpu is dead; no one can alloc from it. */
                         nc = cachep->array[cpu];
                         cachep->array[cpu] = NULL;
                         cachep->free_limit -= cachep->batchcount;
                         free_block(cachep, ac_entry(nc), nc->avail);
                         spin_unlock_irq(&cachep->spinlock);
                         kfree(nc);
                 }
                 up(&cache_chain_sem);
                 break;
 #endif
         }
         return NOTIFY_OK;
 bad:
         up(&cache_chain_sem);
         return NOTIFY_BAD;
 }
 
 static struct notifier_block cpucache_notifier = { &cpuup_callback, NULL, 0 };
 
 /* Initialisation.
  * Called after the gfp() functions have been enabled, and before smp_init().
  */
 void __init kmem_cache_init(void)
 {
         size_t left_over;
         struct cache_sizes *sizes;
         struct cache_names *names;
 
         /*
          * 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 kmem_cache_t
          *    structures of all caches, except cache_cache itself: cache_cache
          *    is statically allocated.
          *    Initially an __init data area is used for the head array, it's
          *    replaced with a kmalloc allocated array at the end of the bootstrap.
          * 2) Create the first kmalloc cache.
          *    The kmem_cache_t 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) Resize the head arrays of the kmalloc caches to their final sizes.
          */
 
         /* 1) create the cache_cache */
         init_MUTEX(&cache_chain_sem);
         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.objsize = ALIGN(cache_cache.objsize, cache_line_size());
 
         cache_estimate(0, cache_cache.objsize, cache_line_size(), 0,
                                 &left_over, &cache_cache.num);
         if (!cache_cache.num)
                 BUG();
 
         cache_cache.colour = left_over/cache_cache.colour_off;
         cache_cache.colour_next = 0;
         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;
 
         while (sizes->cs_size) {
                 /* 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. */
                 sizes->cs_cachep = kmem_cache_create(names->name,
                         sizes->cs_size, ARCH_KMALLOC_MINALIGN,
                         (ARCH_KMALLOC_FLAGS | SLAB_PANIC), NULL, NULL);
 
                 /* Inc off-slab bufctl limit until the ceiling is hit. */
                 if (!(OFF_SLAB(sizes->cs_cachep))) {
                         offslab_limit = sizes->cs_size-sizeof(struct slab);
                         offslab_limit /= sizeof(kmem_bufctl_t);
                 }
 
                 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 */
         {
                 void * ptr;
                 
                 ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
                 local_irq_disable();
                 BUG_ON(ac_data(&cache_cache) != &initarray_cache.cache);
                 memcpy(ptr, ac_data(&cache_cache), sizeof(struct arraycache_init));
                 cache_cache.array[smp_processor_id()] = ptr;
                 local_irq_enable();
         
                 ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
                 local_irq_disable();
                 BUG_ON(ac_data(malloc_sizes[0].cs_cachep) != &initarray_generic.cache);
                 memcpy(ptr, ac_data(malloc_sizes[0].cs_cachep),
                                 sizeof(struct arraycache_init));
                 malloc_sizes[0].cs_cachep->array[smp_processor_id()] = ptr;
                 local_irq_enable();
         }
 
         /* 5) resize the head arrays to their final sizes */
         {
                 kmem_cache_t *cachep;
                 down(&cache_chain_sem);
                 list_for_each_entry(cachep, &cache_chain, next)
                         enable_cpucache(cachep);
                 up(&cache_chain_sem);
         }
 
         /* Done! */
         g_cpucache_up = FULL;
 
         /* Register a cpu startup notifier callback
          * that initializes ac_data 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.
          */
 }
 
 int __init cpucache_init(void)
 {
         int cpu;
 
         /* 
          * Register the timers that return unneeded
          * pages to gfp.
          */
         for (cpu = 0; cpu < NR_CPUS; cpu++) {
                 if (cpu_online(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(kmem_cache_t *cachep, int flags, int nodeid)
 {
         struct page *page;
         void *addr;
         int i;
 
         flags |= cachep->gfpflags;
         if (likely(nodeid == -1)) {
                 addr = (void*)__get_free_pages(flags, cachep->gfporder);
                 if (!addr)
                         return NULL;
                 page = virt_to_page(addr);
         } else {
                 page = alloc_pages_node(nodeid, flags, cachep->gfporder);
                 if (!page)
                         return NULL;
                 addr = page_address(page);
         }
 
         i = (1 << cachep->gfporder);
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                 atomic_add(i, &slab_reclaim_pages);
         add_page_state(nr_slab, i);
         while (i--) {
                 SetPageSlab(page);
                 page++;
         }
         return addr;
 }
 
 /*
  * Interface to system's page release.
  */
 static void kmem_freepages(kmem_cache_t *cachep, void *addr)
 {
         unsigned long i = (1<<cachep->gfporder);
         struct page *page = virt_to_page(addr);
         const unsigned long nr_freed = i;
 
         while (i--) {
                 if (!TestClearPageSlab(page))
                         BUG();
                 page++;
         }
         sub_page_state(nr_slab, nr_freed);
         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);
 }
 
 #if DEBUG
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static void store_stackinfo(kmem_cache_t *cachep, unsigned long *addr, unsigned long caller)
 {
         int size = obj_reallen(cachep);
 
         addr = (unsigned long *)&((char*)addr)[obj_dbghead(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(kmem_cache_t *cachep, void *addr, unsigned char val)
 {
         int size = obj_reallen(cachep);
         addr = &((char*)addr)[obj_dbghead(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
 
 static void print_objinfo(kmem_cache_t *cachep, void *objp, int lines)
 {
 #if DEBUG
         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_dbghead(cachep);
         size = obj_reallen(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);
         }
 #endif
 }
 
 #if DEBUG
 
 static void check_poison_obj(kmem_cache_t *cachep, void *objp)
 {
         char *realobj;
         int size, i;
         int lines = 0;
 
         realobj = (char*)objp+obj_dbghead(cachep);
         size = obj_reallen(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 = GET_PAGE_SLAB(virt_to_page(objp));
                 int objnr;
 
                 objnr = (objp-slabp->s_mem)/cachep->objsize;
                 if (objnr) {
                         objp = slabp->s_mem+(objnr-1)*cachep->objsize;
                         realobj = (char*)objp+obj_dbghead(cachep);
                         printk(KERN_ERR "Prev obj: start=%p, len=%d\n",
                                                 realobj, size);
                         print_objinfo(cachep, objp, 2);
                 }
                 if (objnr+1 < cachep->num) {
                         objp = slabp->s_mem+(objnr+1)*cachep->objsize;
                         realobj = (char*)objp+obj_dbghead(cachep);
                         printk(KERN_ERR "Next obj: start=%p, len=%d\n",
                                                 realobj, size);
                         print_objinfo(cachep, objp, 2);
                 }
         }
 }
 #endif
 
 /* 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 (kmem_cache_t *cachep, struct slab *slabp)
 {
 #if DEBUG
         int i;
         for (i = 0; i < cachep->num; i++) {
                 void *objp = slabp->s_mem + cachep->objsize * i;
 
                 if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                         if ((cachep->objsize%PAGE_SIZE)==0 && OFF_SLAB(cachep))
                                 kernel_map_pages(virt_to_page(objp), cachep->objsize/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_dbghead(cachep), cachep, 0);
         }
 #else
         if (cachep->dtor) {
                 int i;
                 for (i = 0; i < cachep->num; i++) {
                         void* objp = slabp->s_mem+cachep->objsize*i;
                         (cachep->dtor)(objp, cachep, 0);
                 }
         }
 #endif
         
         kmem_freepages(cachep, slabp->s_mem-slabp->colouroff);
         if (OFF_SLAB(cachep))
                 kmem_cache_free(cachep->slabp_cache, slabp);
 }
 
 /**
  * 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_NO_REAP - Don't automatically reap this cache when we're under
  * memory pressure.
  *
  * %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.
  */
 kmem_cache_t *
 kmem_cache_create (const char *name, size_t size, size_t align,
         unsigned long flags, void (*ctor)(void*, kmem_cache_t *, unsigned long),
         void (*dtor)(void*, kmem_cache_t *, unsigned long))
 {
         size_t left_over, slab_size;
         kmem_cache_t *cachep = NULL;
 
         /*
          * 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();
                 }
 
 #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;
         flags |= SLAB_POISON;
 #endif
 #endif
         /*
          * Always checks flags, a caller might be expecting debug
          * support which isn't available.
          */
         if (flags & ~CREATE_MASK)
                 BUG();
 
         if (align) {
                 /* combinations of forced alignment and advanced debugging is
                  * not yet implemented.
                  */
                 flags &= ~(SLAB_RED_ZONE|SLAB_STORE_USER);
         } else {
                 if (flags & SLAB_HWCACHE_ALIGN) {
                         /* Default alignment: as specified by the arch code.
                          * Except if an object is really small, then squeeze multiple
                          * into one cacheline.
                          */
                         align = cache_line_size();
                         while (size <= align/2)
                                 align /= 2;
                 } else {
                         align = BYTES_PER_WORD;
                 }
         }
 
         /* Get cache's description obj. */
         cachep = (kmem_cache_t *) kmem_cache_alloc(&cache_cache, SLAB_KERNEL);
         if (!cachep)
                 goto opps;
         memset(cachep, 0, sizeof(kmem_cache_t));
 
         /* 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);
         }
         
 #if DEBUG
         cachep->reallen = size;
 
         if (flags & SLAB_RED_ZONE) {
                 /* redzoning only works with word aligned caches */
                 align = BYTES_PER_WORD;
 
                 /* add space for red zone words */
                 cachep->dbghead += 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 > 128 && cachep->reallen > cache_line_size() && size < PAGE_SIZE) {
                 cachep->dbghead += PAGE_SIZE - size;
                 size = PAGE_SIZE;
         }
 #endif
 #endif
 
         /* Determine if the slab management is 'on' or 'off' slab. */
         if (size >= (PAGE_SIZE>>3))
                 /*
                  * 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);
 
         if ((flags & SLAB_RECLAIM_ACCOUNT) && size <= PAGE_SIZE) {
                 /*
                  * 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.
                  */
                 cachep->gfporder = 0;
                 cache_estimate(cachep->gfporder, size, align, flags,
                                         &left_over, &cachep->num);
         } else {
                 /*
                  * Calculate size (in pages) of slabs, and the num of objs per
                  * slab.  This could be made much more intelligent.  For now,
                  * try to avoid using high page-orders for slabs.  When the
                  * gfp() funcs are more friendly towards high-order requests,
                  * this should be changed.
                  */
                 do {
                         unsigned int break_flag = 0;
 cal_wastage:
                         cache_estimate(cachep->gfporder, size, align, flags,
                                                 &left_over, &cachep->num);
                         if (break_flag)
                                 break;
                         if (cachep->gfporder >= MAX_GFP_ORDER)
                                 break;
                         if (!cachep->num)
                                 goto next;
                         if (flags & CFLGS_OFF_SLAB &&
                                         cachep->num > offslab_limit) {
                                 /* This num of objs will cause problems. */
                                 cachep->gfporder--;
                                 break_flag++;
                                 goto cal_wastage;
                         }
 
                         /*
                          * Large num of objs is good, but v. large slabs are
                          * currently bad for the gfp()s.
                          */
                         if (cachep->gfporder >= slab_break_gfp_order)
                                 break;
 
                         if ((left_over*8) <= (PAGE_SIZE<<cachep->gfporder))
                                 break;  /* Acceptable internal fragmentation. */
 next:
                         cachep->gfporder++;
                 } while (1);
         }
 
         if (!cachep->num) {
                 printk("kmem_cache_create: couldn't create cache %s.\n", name);
                 kmem_cache_free(&cache_cache, cachep);
                 cachep = NULL;
                 goto opps;
         }
         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;
         spin_lock_init(&cachep->spinlock);
         cachep->objsize = size;
         /* NUMA */
         INIT_LIST_HEAD(&cachep->lists.slabs_full);
         INIT_LIST_HEAD(&cachep->lists.slabs_partial);
         INIT_LIST_HEAD(&cachep->lists.slabs_free);
 
         if (flags & CFLGS_OFF_SLAB)
                 cachep->slabp_cache = kmem_find_general_cachep(slab_size,0);
         cachep->ctor = ctor;
         cachep->dtor = dtor;
         cachep->name = name;
 
         /* Don't let CPUs to come and go */
         lock_cpu_hotplug();
 
         if (g_cpucache_up == FULL) {
                 enable_cpucache(cachep);
         } else {
                 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;
                         g_cpucache_up = PARTIAL;
                 } else {
                         cachep->array[smp_processor_id()] = kmalloc(sizeof(struct arraycache_init),GFP_KERNEL);
                 }
                 BUG_ON(!ac_data(cachep));
                 ac_data(cachep)->avail = 0;
                 ac_data(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
                 ac_data(cachep)->batchcount = 1;
                 ac_data(cachep)->touched = 0;
                 cachep->batchcount = 1;
                 cachep->limit = BOOT_CPUCACHE_ENTRIES;
                 cachep->free_limit = (1+num_online_cpus())*cachep->batchcount
                                         + cachep->num;
         } 
 
         cachep->lists.next_reap = jiffies + REAPTIMEOUT_LIST3 +
                                         ((unsigned long)cachep)%REAPTIMEOUT_LIST3;
 
         /* Need the semaphore to access the chain. */
         down(&cache_chain_sem);
         {
                 struct list_head *p;
                 mm_segment_t old_fs;
 
                 old_fs = get_fs();
                 set_fs(KERNEL_DS);
                 list_for_each(p, &cache_chain) {
                         kmem_cache_t *pc = list_entry(p, kmem_cache_t, next);
                         char tmp;
                         /* This happens when the module gets unloaded and doesn't
                            destroy its slab cache and noone else reuses the vmalloc
                            area of the module. Print a warning. */
                         if (__get_user(tmp,pc->name)) { 
                                 printk("SLAB: cache with size %d has lost its name\n", 
                                         pc->objsize); 
                                 continue; 
                         }       
                         if (!strcmp(pc->name,name)) { 
                                 printk("kmem_cache_create: duplicate cache %s\n",name); 
                                 up(&cache_chain_sem); 
                                 unlock_cpu_hotplug();
                                 BUG(); 
                         }       
                 }
                 set_fs(old_fs);
         }
 
         /* cache setup completed, link it into the list */
         list_add(&cachep->next, &cache_chain);
         up(&cache_chain_sem);
         unlock_cpu_hotplug();
 opps:
         if (!cachep && (flags & SLAB_PANIC))
                 panic("kmem_cache_create(): failed to create slab `%s'\n",
                         name);
         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(kmem_cache_t *cachep)
 {
 #ifdef CONFIG_SMP
         check_irq_off();
         BUG_ON(spin_trylock(&cachep->spinlock));
 #endif
 }
 #else
 #define check_irq_off() do { } while(0)
 #define check_irq_on()  do { } while(0)
 #define check_spinlock_acquired(x) do { } while(0)
 #endif
 
 /*
  * Waits for all CPUs to execute func().
  */
 static void smp_call_function_all_cpus(void (*func) (void *arg), void *arg)
 {
         check_irq_on();
         preempt_disable();
 
         local_irq_disable();
         func(arg);
         local_irq_enable();
 
         if (smp_call_function(func, arg, 1, 1))
                 BUG();
 
         preempt_enable();
 }
 
 static void drain_array_locked(kmem_cache_t* cachep,
                                 struct array_cache *ac, int force);
 
 static void do_drain(void *arg)
 {
         kmem_cache_t *cachep = (kmem_cache_t*)arg;
         struct array_cache *ac;
 
         check_irq_off();
         ac = ac_data(cachep);
         spin_lock(&cachep->spinlock);
         free_block(cachep, &ac_entry(ac)[0], ac->avail);
         spin_unlock(&cachep->spinlock);
         ac->avail = 0;
 }
 
 static void drain_cpu_caches(kmem_cache_t *cachep)
 {
         smp_call_function_all_cpus(do_drain, cachep);
         check_irq_on();
         spin_lock_irq(&cachep->spinlock);
         if (cachep->lists.shared)
                 drain_array_locked(cachep, cachep->lists.shared, 1);
         spin_unlock_irq(&cachep->spinlock);
 }
 
 
 /* NUMA shrink all list3s */
 static int __cache_shrink(kmem_cache_t *cachep)
 {
         struct slab *slabp;
         int ret;
 
         drain_cpu_caches(cachep);
 
         check_irq_on();
         spin_lock_irq(&cachep->spinlock);
 
         for(;;) {
                 struct list_head *p;
 
                 p = cachep->lists.slabs_free.prev;
                 if (p == &cachep->lists.slabs_free)
                         break;
 
                 slabp = list_entry(cachep->lists.slabs_free.prev, struct slab, list);
 #if DEBUG
                 if (slabp->inuse)
                         BUG();
 #endif
                 list_del(&slabp->list);
 
                 cachep->lists.free_objects -= cachep->num;
                 spin_unlock_irq(&cachep->spinlock);
                 slab_destroy(cachep, slabp);
                 spin_lock_irq(&cachep->spinlock);
         }
         ret = !list_empty(&cachep->lists.slabs_full) ||
                 !list_empty(&cachep->lists.slabs_partial);
         spin_unlock_irq(&cachep->spinlock);
         return ret;
 }
 
 /**
  * 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(kmem_cache_t *cachep)
 {
         if (!cachep || in_interrupt())
                 BUG();
 
         return __cache_shrink(cachep);
 }
 
 EXPORT_SYMBOL(kmem_cache_shrink);
 
 /**
  * kmem_cache_destroy - delete a cache
  * @cachep: the cache to destroy
  *
  * Remove a kmem_cache_t 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 (kmem_cache_t * cachep)
 {
         int i;
 
         if (!cachep || in_interrupt())
                 BUG();
 
         /* Don't let CPUs to come and go */
         lock_cpu_hotplug();
 
         /* Find the cache in the chain of caches. */
         down(&cache_chain_sem);
         /*
          * the chain is never empty, cache_cache is never destroyed
          */
         list_del(&cachep->next);
         up(&cache_chain_sem);
 
         if (__cache_shrink(cachep)) {
                 slab_error(cachep, "Can't free all objects");
                 down(&cache_chain_sem);
                 list_add(&cachep->next,&cache_chain);
                 up(&cache_chain_sem);
                 unlock_cpu_hotplug();
                 return 1;
         }
 
         /* no cpu_online check required here since we clear the percpu
          * array on cpu offline and set this to NULL.
          */
         for (i = 0; i < NR_CPUS; i++)
                 kfree(cachep->array[i]);
 
         /* NUMA: free the list3 structures */
         kfree(cachep->lists.shared);
         cachep->lists.shared = NULL;
         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 (kmem_cache_t *cachep,
                         void *objp, int colour_off, int local_flags)
 {
         struct slab *slabp;
         
         if (OFF_SLAB(cachep)) {
                 /* Slab management obj is off-slab. */
                 slabp = kmem_cache_alloc(cachep->slabp_cache, local_flags);
                 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;
 
         return slabp;
 }
 
 static inline kmem_bufctl_t *slab_bufctl(struct slab *slabp)
 {
         return (kmem_bufctl_t *)(slabp+1);
 }
 
 static void cache_init_objs (kmem_cache_t * cachep,
                         struct slab * slabp, unsigned long ctor_flags)
 {
         int i;
 
         for (i = 0; i < cachep->num; i++) {
                 void* objp = slabp->s_mem+cachep->objsize*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_dbghead(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->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
                         kernel_map_pages(virt_to_page(objp), cachep->objsize/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(kmem_cache_t *cachep, int flags)
 {
         if (flags & SLAB_DMA) {
                 if (!(cachep->gfpflags & GFP_DMA))
                         BUG();
         } else {
                 if (cachep->gfpflags & GFP_DMA)
                         BUG();
         }
 }
 
 static void set_slab_attr(kmem_cache_t *cachep, struct slab *slabp, void *objp)
 {
         int i;
         struct page *page;
 
         /* Nasty!!!!!! I hope this is OK. */
         i = 1 << cachep->gfporder;
         page = virt_to_page(objp);
         do {
                 SET_PAGE_CACHE(page, cachep);
                 SET_PAGE_SLAB(page, slabp);
                 page++;
         } while (--i);
 }
 
 /*
  * 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 (kmem_cache_t * cachep, int flags)
 {
         struct slab     *slabp;
         void            *objp;
         size_t           offset;
         int              local_flags;
         unsigned long    ctor_flags;
 
         /* Be lazy and only check for valid flags here,
          * keeping it out of the critical path in kmem_cache_alloc().
          */
         if (flags & ~(SLAB_DMA|SLAB_LEVEL_MASK|SLAB_NO_GROW))
                 BUG();
         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;
 
         /* About to mess with non-constant members - lock. */
         check_irq_off();
         spin_lock(&cachep->spinlock);
 
         /* Get colour for the slab, and cal the next value. */
         offset = cachep->colour_next;
         cachep->colour_next++;
         if (cachep->colour_next >= cachep->colour)
                 cachep->colour_next = 0;
         offset *= cachep->colour_off;
 
         spin_unlock(&cachep->spinlock);
 
         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. */
         if (!(objp = kmem_getpages(cachep, flags, -1)))
                 goto failed;
 
         /* Get slab management. */
         if (!(slabp = alloc_slabmgmt(cachep, objp, offset, local_flags)))
                 goto opps1;
 
         set_slab_attr(cachep, slabp, objp);
 
         cache_init_objs(cachep, slabp, ctor_flags);
 
         if (local_flags & __GFP_WAIT)
                 local_irq_disable();
         check_irq_off();
         spin_lock(&cachep->spinlock);
 
         /* Make slab active. */
         list_add_tail(&slabp->list, &(list3_data(cachep)->slabs_free));
         STATS_INC_GROWN(cachep);
         list3_data(cachep)->free_objects += cachep->num;
         spin_unlock(&cachep->spinlock);
         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 void *cache_free_debugcheck (kmem_cache_t * cachep, void * objp, void *caller)
 {
         struct page *page;
         unsigned int objnr;
         struct slab *slabp;
 
         objp -= obj_dbghead(cachep);
         kfree_debugcheck(objp);
         page = virt_to_page(objp);
 
         if (GET_PAGE_CACHE(page) != cachep) {
                 printk(KERN_ERR "mismatch in kmem_cache_free: expected cache %p, got %p\n",
                                 GET_PAGE_CACHE(page),cachep);
                 printk(KERN_ERR "%p is %s.\n", cachep, cachep->name);
                 printk(KERN_ERR "%p is %s.\n", GET_PAGE_CACHE(page), GET_PAGE_CACHE(page)->name);
                 WARN_ON(1);
         }
         slabp = GET_PAGE_SLAB(page);
 
         if (cachep->flags & SLAB_RED_ZONE) {
                 if (*dbg_redzone1(cachep, objp) != RED_ACTIVE || *dbg_redzone2(cachep, objp) != RED_ACTIVE) {
                         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_INACTIVE;
                 *dbg_redzone2(cachep, objp) = RED_INACTIVE;
         }
         if (cachep->flags & SLAB_STORE_USER)
                 *dbg_userword(cachep, objp) = caller;
 
         objnr = (objp-slabp->s_mem)/cachep->objsize;
 
         BUG_ON(objnr >= cachep->num);
         BUG_ON(objp != slabp->s_mem + objnr*cachep->objsize);
 
         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_dbghead(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_dbghead(cachep), cachep, 0);
         }
         if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                 if ((cachep->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep)) {
                         store_stackinfo(cachep, objp, (unsigned long)caller);
                         kernel_map_pages(virt_to_page(objp), cachep->objsize/PAGE_SIZE, 0);
                 } else {
                         poison_obj(cachep, objp, POISON_FREE);
                 }
 #else
                 poison_obj(cachep, objp, POISON_FREE);
 #endif
         }
         return objp;
 }
 
 static void check_slabp(kmem_cache_t *cachep, struct slab *slabp)
 {
         int i;
         int entries = 0;
         
         check_spinlock_acquired(cachep);
         /* 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 < 0 || i >= cachep->num)
                         goto bad;
         }
         if (entries != cachep->num - slabp->inuse) {
                 int i;
 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(kmem_cache_t* cachep, int flags)
 {
         int batchcount;
         struct kmem_list3 *l3;
         struct array_cache *ac;
 
         check_irq_off();
         ac = ac_data(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 = list3_data(cachep);
 
         BUG_ON(ac->avail > 0);
         spin_lock(&cachep->spinlock);
         if (l3->shared) {
                 struct array_cache *shared_array = l3->shared;
                 if (shared_array->avail) {
                         if (batchcount > shared_array->avail)
                                 batchcount = shared_array->avail;
                         shared_array->avail -= batchcount;
                         ac->avail = batchcount;
                         memcpy(ac_entry(ac), &ac_entry(shared_array)[shared_array->avail],
                                         sizeof(void*)*batchcount);
                         shared_array->touched = 1;
                         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--) {
                         kmem_bufctl_t next;
                         STATS_INC_ALLOCED(cachep);
                         STATS_INC_ACTIVE(cachep);
                         STATS_SET_HIGH(cachep);
 
                         /* get obj pointer */
                         ac_entry(ac)[ac->avail++] = slabp->s_mem + slabp->free*cachep->objsize;
 
                         slabp->inuse++;
                         next = slab_bufctl(slabp)[slabp->free];
 #if DEBUG
                         slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE;
 #endif
                         slabp->free = next;
                 }
                 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(&cachep->spinlock);
 
         if (unlikely(!ac->avail)) {
                 int x;
                 x = cache_grow(cachep, flags);
                 
                 // cache_grow can reenable interrupts, then ac could change.
                 ac = ac_data(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)[--ac->avail];
 }
 
 static inline void
 cache_alloc_debugcheck_before(kmem_cache_t *cachep, int flags)
 {
         might_sleep_if(flags & __GFP_WAIT);
 #if DEBUG
         kmem_flagcheck(cachep, flags);
 #endif
 }
 
 #if DEBUG
 static void *
 cache_alloc_debugcheck_after(kmem_cache_t *cachep,
                         unsigned long flags, void *objp, void *caller)
 {
         if (!objp)      
                 return objp;
         if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                 if ((cachep->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep))
                         kernel_map_pages(virt_to_page(objp), cachep->objsize/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;
         }
         objp += obj_dbghead(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 (kmem_cache_t *cachep, int flags)
 {
         unsigned long save_flags;
         void* objp;
         struct array_cache *ac;
 
         cache_alloc_debugcheck_before(cachep, flags);
 
         local_irq_save(save_flags);
         ac = ac_data(cachep);
         if (likely(ac->avail)) {
                 STATS_INC_ALLOCHIT(cachep);
                 ac->touched = 1;
                 objp = ac_entry(ac)[--ac->avail];
         } else {
                 STATS_INC_ALLOCMISS(cachep);
                 objp = cache_alloc_refill(cachep, flags);
         }
         local_irq_restore(save_flags);
         objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0));
         return objp;
 }
 
 /* 
  * NUMA: different approach needed if the spinlock is moved into
  * the l3 structure
  */
 
 static void free_block(kmem_cache_t *cachep, void **objpp, int nr_objects)
 {
         int i;
 
         check_spinlock_acquired(cachep);
 
         /* NUMA: move add into loop */
         cachep->lists.free_objects += nr_objects;
 
         for (i = 0; i < nr_objects; i++) {
                 void *objp = objpp[i];
                 struct slab *slabp;
                 unsigned int objnr;
 
                 slabp = GET_PAGE_SLAB(virt_to_page(objp));
                 list_del(&slabp->list);
                 objnr = (objp - slabp->s_mem) / cachep->objsize;
                 check_slabp(cachep, slabp);
 #if DEBUG
                 if (slab_bufctl(slabp)[objnr] != BUFCTL_FREE) {
                         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;
                 STATS_DEC_ACTIVE(cachep);
                 slabp->inuse--;
                 check_slabp(cachep, slabp);
 
                 /* fixup slab chains */
                 if (slabp->inuse == 0) {
                         if (cachep->lists.free_objects > cachep->free_limit) {
                                 cachep->lists.free_objects -= cachep->num;
                                 slab_destroy(cachep, slabp);
                         } else {
                                 list_add(&slabp->list,
                                 &list3_data_ptr(cachep, objp)->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,
                                 &list3_data_ptr(cachep, objp)->slabs_partial);
                 }
         }
 }
 
 static void cache_flusharray (kmem_cache_t* cachep, struct array_cache *ac)
 {
         int batchcount;
 
         batchcount = ac->batchcount;
 #if DEBUG
         BUG_ON(!batchcount || batchcount > ac->avail);
 #endif
         check_irq_off();
         spin_lock(&cachep->spinlock);
         if (cachep->lists.shared) {
                 struct array_cache *shared_array = cachep->lists.shared;
                 int max = shared_array->limit-shared_array->avail;
                 if (max) {
                         if (batchcount > max)
                                 batchcount = max;
                         memcpy(&ac_entry(shared_array)[shared_array->avail],
                                         &ac_entry(ac)[0],
                                         sizeof(void*)*batchcount);
                         shared_array->avail += batchcount;
                         goto free_done;
                 }
         }
 
         free_block(cachep, &ac_entry(ac)[0], batchcount);
 free_done:
 #if STATS
         {
                 int i = 0;
                 struct list_head *p;
 
                 p = list3_data(cachep)->slabs_free.next;
                 while (p != &(list3_data(cachep)->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(&cachep->spinlock);
         ac->avail -= batchcount;
         memmove(&ac_entry(ac)[0], &ac_entry(ac)[batchcount],
                         sizeof(void*)*ac->avail);
 }
 
 /*
  * __cache_free
  * 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 (kmem_cache_t *cachep, void* objp)
 {
         struct array_cache *ac = ac_data(cachep);
 
         check_irq_off();
         objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));
 
         if (likely(ac->avail < ac->limit)) {
                 STATS_INC_FREEHIT(cachep);
                 ac_entry(ac)[ac->avail++] = objp;
                 return;
         } else {
                 STATS_INC_FREEMISS(cachep);
                 cache_flusharray(cachep, ac);
                 ac_entry(ac)[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 (kmem_cache_t *cachep, int flags)
 {
         return __cache_alloc(cachep, flags);
 }
 
 EXPORT_SYMBOL(kmem_cache_alloc);
 
 /**
  * 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(kmem_cache_t *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->objsize;
         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(GET_PAGE_CACHE(page) != cachep))
                 goto out;
         return 1;
 out:
         return 0;
 }
 
 /**
  * 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.
  */
 void *kmem_cache_alloc_node(kmem_cache_t *cachep, int nodeid)
 {
         size_t offset;
         void *objp;
         struct slab *slabp;
         kmem_bufctl_t next;
 
         /* The main algorithms are not node aware, thus we have to cheat:
          * We bypass all caches and allocate a new slab.
          * The following code is a streamlined copy of cache_grow().
          */
 
         /* Get colour for the slab, and update the next value. */
         spin_lock_irq(&cachep->spinlock);
         offset = cachep->colour_next;
         cachep->colour_next++;
         if (cachep->colour_next >= cachep->colour)
                 cachep->colour_next = 0;
         offset *= cachep->colour_off;
         spin_unlock_irq(&cachep->spinlock);
 
         /* Get mem for the objs. */
         if (!(objp = kmem_getpages(cachep, GFP_KERNEL, nodeid)))
                 goto failed;
 
         /* Get slab management. */
         if (!(slabp = alloc_slabmgmt(cachep, objp, offset, GFP_KERNEL)))
                 goto opps1;
 
         set_slab_attr(cachep, slabp, objp);
         cache_init_objs(cachep, slabp, SLAB_CTOR_CONSTRUCTOR);
 
         /* The first object is ours: */
         objp = slabp->s_mem + slabp->free*cachep->objsize;
         slabp->inuse++;
         next = slab_bufctl(slabp)[slabp->free];
 #if DEBUG
         slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE;
 #endif
         slabp->free = next;
 
         /* add the remaining objects into the cache */
         spin_lock_irq(&cachep->spinlock);
         check_slabp(cachep, slabp);
         STATS_INC_GROWN(cachep);
         /* Make slab active. */
         if (slabp->free == BUFCTL_END) {
                 list_add_tail(&slabp->list, &(list3_data(cachep)->slabs_full));
         } else {
                 list_add_tail(&slabp->list,
                                 &(list3_data(cachep)->slabs_partial));
                 list3_data(cachep)->free_objects += cachep->num-1;
         }
         spin_unlock_irq(&cachep->spinlock);
         objp = cache_alloc_debugcheck_after(cachep, GFP_KERNEL, objp,
                                         __builtin_return_address(0));
         return objp;
 opps1:
         kmem_freepages(cachep, objp);
 failed:
         return NULL;
 
 }
 EXPORT_SYMBOL(kmem_cache_alloc_node);
 
 /**
  * kmalloc - allocate memory
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate.
  *
  * kmalloc is the normal method of allocating memory
  * in the kernel.
  *
  * The @flags argument may be one of:
  *
  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
  *
  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
  *
  * %GFP_ATOMIC - Allocation will not sleep.  Use inside interrupt handlers.
  *
  * Additionally, the %GFP_DMA flag may be set to indicate the memory
  * must be suitable for DMA.  This can mean different things on different
  * platforms.  For example, on i386, it means that the memory must come
  * from the first 16MB.
  */
 void * __kmalloc (size_t size, int flags)
 {
         struct cache_sizes *csizep = malloc_sizes;
 
         for (; csizep->cs_size; csizep++) {
                 if (size > csizep->cs_size)
                         continue;
 #if DEBUG
                 /* This happens if someone tries to call
                  * kmem_cache_create(), or kmalloc(), before
                  * the generic caches are initialized.
                  */
                 BUG_ON(csizep->cs_cachep == NULL);
 #endif
                 return __cache_alloc(flags & GFP_DMA ?
                          csizep->cs_dmacachep : csizep->cs_cachep, flags);
         }
         return NULL;
 }
 
 EXPORT_SYMBOL(__kmalloc);
 
 #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 per_cpu_ptr/get_cpu_ptr
  * macros only.
  *
  * @size: how many bytes of memory are required.
  * @align: the alignment, which can't be greater than SMP_CACHE_BYTES.
  */
 void *__alloc_percpu(size_t size, size_t align)
 {
         int i;
         struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL);
 
         if (!pdata)
                 return NULL;
 
         for (i = 0; i < NR_CPUS; i++) {
                 if (!cpu_possible(i))
                         continue;
                 pdata->ptrs[i] = kmem_cache_alloc_node(
                                 kmem_find_general_cachep(size, GFP_KERNEL),
                                 cpu_to_node(i));
 
                 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 (kmem_cache_t *cachep, void *objp)
 {
         unsigned long flags;
 
         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.
  *
  * Don't free memory not originally allocated by kmalloc()
  * or you will run into trouble.
  */
 void kfree (const void *objp)
 {
         kmem_cache_t *c;
         unsigned long flags;
 
         if (!objp)
                 return;
         local_irq_save(flags);
         kfree_debugcheck(objp);
         c = GET_PAGE_CACHE(virt_to_page(objp));
         __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);
 
         for (i = 0; i < NR_CPUS; i++) {
                 if (!cpu_possible(i))
                         continue;
                 kfree(p->ptrs[i]);
         }
 }
 
 EXPORT_SYMBOL(free_percpu);
 #endif
 
 unsigned int kmem_cache_size(kmem_cache_t *cachep)
 {
         return obj_reallen(cachep);
 }
 
 EXPORT_SYMBOL(kmem_cache_size);
 
 kmem_cache_t * kmem_find_general_cachep (size_t size, int gfpflags)
 {
         struct cache_sizes *csizep = malloc_sizes;
 
         /* This function could be moved to the header file, and
          * made inline so consumers can quickly determine what
          * cache pointer they require.
          */
         for ( ; csizep->cs_size; csizep++) {
                 if (size > csizep->cs_size)
                         continue;
                 break;
         }
         return (gfpflags & GFP_DMA) ? csizep->cs_dmacachep : csizep->cs_cachep;
 }
 
 EXPORT_SYMBOL(kmem_find_general_cachep);
 
 struct ccupdate_struct {
         kmem_cache_t *cachep;
         struct array_cache *new[NR_CPUS];
 };
 
 static void do_ccupdate_local(void *info)
 {
         struct ccupdate_struct *new = (struct ccupdate_struct *)info;
         struct array_cache *old;
 
         check_irq_off();
         old = ac_data(new->cachep);
         
         new->cachep->array[smp_processor_id()] = new->new[smp_processor_id()];
         new->new[smp_processor_id()] = old;
 }
 
 
 static int do_tune_cpucache (kmem_cache_t* cachep, int limit, int batchcount, int shared)
 {
         struct ccupdate_struct new;
         struct array_cache *new_shared;
         int i;
 
         memset(&new.new,0,sizeof(new.new));
         for (i = 0; i < NR_CPUS; i++) {
                 if (cpu_online(i)) {
                         new.new[i] = alloc_arraycache(i, limit, batchcount);
                         if (!new.new[i]) {
                                 for (i--; i >= 0; i--) kfree(new.new[i]);
                                 return -ENOMEM;
                         }
                 } else {
                         new.new[i] = NULL;
                 }
         }
         new.cachep = cachep;
 
         smp_call_function_all_cpus(do_ccupdate_local, (void *)&new);
         
         check_irq_on();
         spin_lock_irq(&cachep->spinlock);
         cachep->batchcount = batchcount;
         cachep->limit = limit;
         cachep->free_limit = (1+num_online_cpus())*cachep->batchcount + cachep->num;
         spin_unlock_irq(&cachep->spinlock);
 
         for (i = 0; i < NR_CPUS; i++) {
                 struct array_cache *ccold = new.new[i];
                 if (!ccold)
                         continue;
                 spin_lock_irq(&cachep->spinlock);
                 free_block(cachep, ac_entry(ccold), ccold->avail);
                 spin_unlock_irq(&cachep->spinlock);
                 kfree(ccold);
         }
         new_shared = alloc_arraycache(-1, batchcount*shared, 0xbaadf00d);
         if (new_shared) {
                 struct array_cache *old;
 
                 spin_lock_irq(&cachep->spinlock);
                 old = cachep->lists.shared;
                 cachep->lists.shared = new_shared;
                 if (old)
                         free_block(cachep, ac_entry(old), old->avail);
                 spin_unlock_irq(&cachep->spinlock);
                 kfree(old);
         }
 
         return 0;
 }
 
 
 static void enable_cpucache (kmem_cache_t *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->objsize > 131072)
                 limit = 1;
         else if (cachep->objsize > PAGE_SIZE)
                 limit = 8;
         else if (cachep->objsize > 1024)
                 limit = 24;
         else if (cachep->objsize > 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->objsize <= 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);
 }
 
 static void drain_array(kmem_cache_t *cachep, struct array_cache *ac)
 {
         int tofree;
 
         check_irq_off();
         if (ac->touched) {
                 ac->touched = 0;
         } else if (ac->avail) {
                 tofree = (ac->limit+4)/5;
                 if (tofree > ac->avail) {
                         tofree = (ac->avail+1)/2;
                 }
                 spin_lock(&cachep->spinlock);
                 free_block(cachep, ac_entry(ac), tofree);
                 spin_unlock(&cachep->spinlock);
                 ac->avail -= tofree;
                 memmove(&ac_entry(ac)[0], &ac_entry(ac)[tofree],
                                         sizeof(void*)*ac->avail);
         }
 }
 
 static void drain_array_locked(kmem_cache_t *cachep,
                                 struct array_cache *ac, int force)
 {
         int tofree;
 
         check_spinlock_acquired(cachep);
         if (ac->touched && !force) {
                 ac->touched = 0;
         } else 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(ac), tofree);
                 ac->avail -= tofree;
                 memmove(&ac_entry(ac)[0], &ac_entry(ac)[tofree],
                                         sizeof(void*)*ac->avail);
         }
 }
 
 /**
  * cache_reap - Reclaim memory from caches.
  *
  * Called from a timer, 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 semaphore then just give up - we'll
  * try again next timer interrupt.
  */
 static void cache_reap (void)
 {
         struct list_head *walk;
 
 #if DEBUG
         BUG_ON(!in_interrupt());
         BUG_ON(in_irq());
 #endif
         if (down_trylock(&cache_chain_sem))
                 return;
 
         list_for_each(walk, &cache_chain) {
                 kmem_cache_t *searchp;
                 struct list_head* p;
                 int tofree;
                 struct slab *slabp;
 
                 searchp = list_entry(walk, kmem_cache_t, next);
 
                 if (searchp->flags & SLAB_NO_REAP)
                         goto next;
 
                 check_irq_on();
                 local_irq_disable();
                 drain_array(searchp, ac_data(searchp));
 
                 if(time_after(searchp->lists.next_reap, jiffies))
                         goto next_irqon;
 
                 spin_lock(&searchp->spinlock);
                 if(time_after(searchp->lists.next_reap, jiffies)) {
                         goto next_unlock;
                 }
                 searchp->lists.next_reap = jiffies + REAPTIMEOUT_LIST3;
 
                 if (searchp->lists.shared)
                         drain_array_locked(searchp, searchp->lists.shared, 0);
 
                 if (searchp->lists.free_touched) {
                         searchp->lists.free_touched = 0;
                         goto next_unlock;
                 }
 
                 tofree = (searchp->free_limit+5*searchp->num-1)/(5*searchp->num);
                 do {
                         p = list3_data(searchp)->slabs_free.next;
                         if (p == &(list3_data(searchp)->slabs_free))
                                 break;
 
                         slabp = list_entry(p, struct slab, list);
                         BUG_ON(slabp->inuse);
                         list_del(&slabp->list);
                         STATS_INC_REAPED(searchp);
 
                         /* Safe to drop the lock. The slab is no longer
                          * linked to the cache.
                          * searchp cannot disappear, we hold
                          * cache_chain_lock
                          */
                         searchp->lists.free_objects -= searchp->num;
                         spin_unlock_irq(&searchp->spinlock);
                         slab_destroy(searchp, slabp);
                         spin_lock_irq(&searchp->spinlock);
                 } while(--tofree > 0);
 next_unlock:
                 spin_unlock(&searchp->spinlock);
 next_irqon:
                 local_irq_enable();
 next:
                 ;
         }
         check_irq_on();
         up(&cache_chain_sem);
 }
 
 /*
  * This is a timer handler.  There is one per CPU.  It is called periodially
  * to shrink this CPU's caches.  Otherwise there could be memory tied up
  * for long periods (or for ever) due to load changes.
  */
 static void reap_timer_fnc(unsigned long cpu)
 {
         struct timer_list *rt = &__get_cpu_var(reap_timers);
 
         /* CPU hotplug can drag us off cpu: don't run on wrong CPU */
         if (!cpu_is_offline(cpu)) {
                 cache_reap();
                 mod_timer(rt, jiffies + REAPTIMEOUT_CPUC + cpu);
         }
 }
 
 #ifdef CONFIG_PROC_FS
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
         loff_t n = *pos;
         struct list_head *p;
 
         down(&cache_chain_sem);
         if (!n) {
                 /*
                  * Output format version, so at least we can change it
                  * without _too_ many complaints.
                  */
 #if STATS
                 seq_puts(m, "slabinfo - version: 2.0 (statistics)\n");
 #else
                 seq_puts(m, "slabinfo - version: 2.0\n");
 #endif
                 seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
                 seq_puts(m, " : tunables <batchcount> <limit> <sharedfactor>");
                 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
 #if STATS
                 seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <freelimit>");
                 seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
 #endif
                 seq_putc(m, '\n');
         }
         p = cache_chain.next;
         while (n--) {
                 p = p->next;
                 if (p == &cache_chain)
                         return NULL;
         }
         return list_entry(p, kmem_cache_t, next);
 }
 
 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 {
         kmem_cache_t *cachep = p;
         ++*pos;
         return cachep->next.next == &cache_chain ? NULL
                 : list_entry(cachep->next.next, kmem_cache_t, next);
 }
 
 static void s_stop(struct seq_file *m, void *p)
 {
         up(&cache_chain_sem);
 }
 
 static int s_show(struct seq_file *m, void *p)
 {
         kmem_cache_t *cachep = p;
         struct list_head *q;
         struct slab     *slabp;
         unsigned long   active_objs;
         unsigned long   num_objs;
         unsigned long   active_slabs = 0;
         unsigned long   num_slabs;
         const char *name; 
         char *error = NULL;
 
         check_irq_on();
         spin_lock_irq(&cachep->spinlock);
         active_objs = 0;
         num_slabs = 0;
         list_for_each(q,&cachep->lists.slabs_full) {
                 slabp = list_entry(q, struct slab, list);
                 if (slabp->inuse != cachep->num && !error)
                         error = "slabs_full accounting error";
                 active_objs += cachep->num;
                 active_slabs++;
         }
         list_for_each(q,&cachep->lists.slabs_partial) {
                 slabp = list_entry(q, struct slab, 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(q,&cachep->lists.slabs_free) {
                 slabp = list_entry(q, struct slab, list);
                 if (slabp->inuse && !error)
                         error = "slabs_free/inuse accounting error";
                 num_slabs++;
         }
         num_slabs+=active_slabs;
         num_objs = num_slabs*cachep->num;
         if (num_objs - active_objs != cachep->lists.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->objsize,
                 cachep->num, (1<<cachep->gfporder));
         seq_printf(m, " : tunables %4u %4u %4u",
                         cachep->limit, cachep->batchcount,
                         cachep->lists.shared->limit/cachep->batchcount);
         seq_printf(m, " : slabdata %6lu %6lu %6u",
                         active_slabs, num_slabs, cachep->lists.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 free_limit = cachep->free_limit;
 
                 seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu",
                                 allocs, high, grown, reaped, errors, 
                                 max_freeable, free_limit);
         }
         /* 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');
         spin_unlock_irq(&cachep->spinlock);
         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 list_head *p;
         
         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. */
         down(&cache_chain_sem);
         res = -EINVAL;
         list_for_each(p,&cache_chain) {
                 kmem_cache_t *cachep = list_entry(p, kmem_cache_t, next);
 
                 if (!strcmp(cachep->name, kbuf)) {
                         if (limit < 1 ||
                             batchcount < 1 ||
                             batchcount > limit ||
                             shared < 0) {
                                 res = -EINVAL;
                         } else {
                                 res = do_tune_cpucache(cachep, limit, batchcount, shared);
                         }
                         break;
                 }
         }
         up(&cache_chain_sem);
         if (res >= 0)
                 res = count;
         return res;
 }
 #endif
 
 unsigned int ksize(const void *objp)
 {
         kmem_cache_t *c;
         unsigned long flags;
         unsigned int size = 0;
 
         if (likely(objp != NULL)) {
                 local_irq_save(flags);
                 c = GET_PAGE_CACHE(virt_to_page(objp));
                 size = kmem_cache_size(c);
                 local_irq_restore(flags);
         }
 
         return size;
 }
 
 void ptrinfo(unsigned long addr)
 {
         struct page *page;
 
         printk("Dumping data about address %p.\n", (void*)addr);
         if (!virt_addr_valid((void*)addr)) {
                 printk("virt addr invalid.\n");
                 return;
         }
 #ifdef CONFIG_MMU
         do {
                 pgd_t *pgd = pgd_offset_k(addr);
                 pmd_t *pmd;
                 if (pgd_none(*pgd)) {
                         printk("No pgd.\n");
                         break;
                 }
                 pmd = pmd_offset(pgd, addr);
                 if (pmd_none(*pmd)) {
                         printk("No pmd.\n");
                         break;
                 }
 #ifdef CONFIG_X86
                 if (pmd_large(*pmd)) {
                         printk("Large page.\n");
                         break;
                 }
 #endif
                 printk("normal page, pte_val 0x%llx\n",
                   (unsigned long long)pte_val(*pte_offset_kernel(pmd, addr)));
         } while(0);
 #endif
 
         page = virt_to_page((void*)addr);
         printk("struct page at %p, flags %08lx\n",
                         page, (unsigned long)page->flags);
         if (PageSlab(page)) {
                 kmem_cache_t *c;
                 struct slab *s;
                 unsigned long flags;
                 int objnr;
                 void *objp;
 
                 c = GET_PAGE_CACHE(page);
                 printk("belongs to cache %s.\n",c->name);
 
                 spin_lock_irqsave(&c->spinlock, flags);
                 s = GET_PAGE_SLAB(page);
                 printk("slabp %p with %d inuse objects (from %d).\n",
                         s, s->inuse, c->num);
                 check_slabp(c,s);
 
                 objnr = (addr-(unsigned long)s->s_mem)/c->objsize;
                 objp = s->s_mem+c->objsize*objnr;
                 printk("points into object no %d, starting at %p, len %d.\n",
                         objnr, objp, c->objsize);
                 if (objnr >= c->num) {
                         printk("Bad obj number.\n");
                 } else {
                         kernel_map_pages(virt_to_page(objp),
                                         c->objsize/PAGE_SIZE, 1);
 
                         print_objinfo(c, objp, 2);
                 }
                 spin_unlock_irqrestore(&c->spinlock, flags);
 
         }
 }
 

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