Cross-Referenced Linux and Device Driver Code

   /*
    * linux/mm/slab.c
    * Written by Mark Hemment, 1996/97.
    * (markhe@nextd.demon.co.uk)
    *
    * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
    *
    * Major cleanup, different bufctl logic, per-cpu arrays
    *      (c) 2000 Manfred Spraul
   *
   * Cleanup, make the head arrays unconditional, preparation for NUMA
   *      (c) 2002 Manfred Spraul
   *
   * An implementation of the Slab Allocator as described in outline in;
   *      UNIX Internals: The New Frontiers by Uresh Vahalia
   *      Pub: Prentice Hall      ISBN 0-13-101908-2
   * or with a little more detail in;
   *      The Slab Allocator: An Object-Caching Kernel Memory Allocator
   *      Jeff Bonwick (Sun Microsystems).
   *      Presented at: USENIX Summer 1994 Technical Conference
   *
   * The memory is organized in caches, one cache for each object type.
   * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
   * Each cache consists out of many slabs (they are small (usually one
   * page long) and always contiguous), and each slab contains multiple
   * initialized objects.
   *
   * This means, that your constructor is used only for newly allocated
   * slabs and you must pass objects with the same initializations to
   * kmem_cache_free.
   *
   * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
   * normal). If you need a special memory type, then must create a new
   * cache for that memory type.
   *
   * In order to reduce fragmentation, the slabs are sorted in 3 groups:
   *   full slabs with 0 free objects
   *   partial slabs
   *   empty slabs with no allocated objects
   *
   * If partial slabs exist, then new allocations come from these slabs,
   * otherwise from empty slabs or new slabs are allocated.
   *
   * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
   * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
   *
   * Each cache has a short per-cpu head array, most allocs
   * and frees go into that array, and if that array overflows, then 1/2
   * of the entries in the array are given back into the global cache.
   * The head array is strictly LIFO and should improve the cache hit rates.
   * On SMP, it additionally reduces the spinlock operations.
   *
   * The c_cpuarray may not be read with enabled local interrupts -
   * it's changed with a smp_call_function().
   *
   * SMP synchronization:
   *  constructors and destructors are called without any locking.
   *  Several members in struct kmem_cache and struct slab never change, they
   *      are accessed without any locking.
   *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
   *      and local interrupts are disabled so slab code is preempt-safe.
   *  The non-constant members are protected with a per-cache irq spinlock.
   *
   * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
   * in 2000 - many ideas in the current implementation are derived from
   * his patch.
   *
   * Further notes from the original documentation:
   *
   * 11 April '97.  Started multi-threading - markhe
   *      The global cache-chain is protected by the mutex 'cache_chain_mutex'.
   *      The sem is only needed when accessing/extending the cache-chain, which
   *      can never happen inside an interrupt (kmem_cache_create(),
   *      kmem_cache_shrink() and kmem_cache_reap()).
   *
   *      At present, each engine can be growing a cache.  This should be blocked.
   *
   * 15 March 2005. NUMA slab allocator.
   *      Shai Fultheim <shai@scalex86.org>.
   *      Shobhit Dayal <shobhit@calsoftinc.com>
   *      Alok N Kataria <alokk@calsoftinc.com>
   *      Christoph Lameter <christoph@lameter.com>
   *
   *      Modified the slab allocator to be node aware on NUMA systems.
   *      Each node has its own list of partial, free and full slabs.
   *      All object allocations for a node occur from node specific slab lists.
   */
  
  #include        <linux/slab.h>
  #include        <linux/mm.h>
  #include        <linux/poison.h>
  #include        <linux/swap.h>
  #include        <linux/cache.h>
  #include        <linux/interrupt.h>
  #include        <linux/init.h>
  #include        <linux/compiler.h>
  #include        <linux/cpuset.h>
  #include        <linux/seq_file.h>
  #include        <linux/notifier.h>
 #include        <linux/kallsyms.h>
 #include        <linux/cpu.h>
 #include        <linux/sysctl.h>
 #include        <linux/module.h>
 #include        <linux/rcupdate.h>
 #include        <linux/string.h>
 #include        <linux/uaccess.h>
 #include        <linux/nodemask.h>
 #include        <linux/mempolicy.h>
 #include        <linux/mutex.h>
 #include        <linux/fault-inject.h>
 #include        <linux/rtmutex.h>
 #include        <linux/reciprocal_div.h>
 
 #include        <asm/cacheflush.h>
 #include        <asm/tlbflush.h>
 #include        <asm/page.h>
 
 /*
  * On !PREEMPT_RT, raw irq flags are used as a per-CPU locking
  * mechanism.
  *
  * On PREEMPT_RT, we use per-CPU locks for this. That's why the
  * calling convention is changed slightly: a new 'flags' argument
  * is passed to 'irq disable/enable' - the PREEMPT_RT code stores
  * the CPU number of the lock there.
  */
 #ifndef CONFIG_PREEMPT_RT
 # define slab_irq_disable(cpu) \
         do { local_irq_disable(); (cpu) = smp_processor_id(); } while (0)
 # define slab_irq_enable(cpu)           local_irq_enable()
 # define slab_irq_save(flags, cpu) \
         do { local_irq_save(flags); (cpu) = smp_processor_id(); } while (0)
 # define slab_irq_restore(flags, cpu)   local_irq_restore(flags)
 /*
  * In the __GFP_WAIT case we enable/disable interrupts on !PREEMPT_RT,
  * which has no per-CPU locking effect since we are holding the cache
  * lock in that case already.
  *
  * (On PREEMPT_RT, these are NOPs, but we have to drop/get the irq locks.)
  */
 # define slab_irq_disable_nort(cpu)     slab_irq_disable(cpu)
 # define slab_irq_enable_nort(cpu)      slab_irq_enable(cpu)
 # define slab_irq_disable_rt(flags)     do { (void)(flags); } while (0)
 # define slab_irq_enable_rt(flags)      do { (void)(flags); } while (0)
 # define slab_spin_lock_irq(lock, cpu) \
         do { spin_lock_irq(lock); (cpu) = smp_processor_id(); } while (0)
 # define slab_spin_unlock_irq(lock, cpu) \
                                         spin_unlock_irq(lock)
 # define slab_spin_lock_irqsave(lock, flags, cpu) \
         do { spin_lock_irqsave(lock, flags); (cpu) = smp_processor_id(); } while (0)
 # define slab_spin_unlock_irqrestore(lock, flags, cpu) \
         do { spin_unlock_irqrestore(lock, flags); } while (0)
 #else
 DEFINE_PER_CPU_LOCKED(int, slab_irq_locks) = { 0, };
 # define slab_irq_disable(cpu)          (void)get_cpu_var_locked(slab_irq_locks, &(cpu))
 # define slab_irq_enable(cpu)           put_cpu_var_locked(slab_irq_locks, cpu)
 # define slab_irq_save(flags, cpu) \
         do { slab_irq_disable(cpu); (void) (flags); } while (0)
 # define slab_irq_restore(flags, cpu) \
         do { slab_irq_enable(cpu); (void) (flags); } while (0)
 # define slab_irq_disable_rt(cpu)       slab_irq_disable(cpu)
 # define slab_irq_enable_rt(cpu)        slab_irq_enable(cpu)
 # define slab_irq_disable_nort(cpu)     do { } while (0)
 # define slab_irq_enable_nort(cpu)      do { } while (0)
 # define slab_spin_lock_irq(lock, cpu) \
                 do { slab_irq_disable(cpu); spin_lock(lock); } while (0)
 # define slab_spin_unlock_irq(lock, cpu) \
                 do { spin_unlock(lock); slab_irq_enable(cpu); } while (0)
 # define slab_spin_lock_irqsave(lock, flags, cpu) \
         do { slab_irq_disable(cpu); spin_lock_irqsave(lock, flags); } while (0)
 # define slab_spin_unlock_irqrestore(lock, flags, cpu) \
         do { spin_unlock_irqrestore(lock, flags); slab_irq_enable(cpu); } while (0)
 #endif
 
 /*
  * DEBUG        - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
  *                0 for faster, smaller code (especially in the critical paths).
  *
  * STATS        - 1 to collect stats for /proc/slabinfo.
  *                0 for faster, smaller code (especially in the critical paths).
  *
  * FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
  */
 
 #ifdef CONFIG_DEBUG_SLAB
 #define DEBUG           1
 #define STATS           1
 #define FORCED_DEBUG    1
 #else
 #define DEBUG           0
 #define STATS           0
 #define FORCED_DEBUG    0
 #endif
 
 /* Shouldn't this be in a header file somewhere? */
 #define BYTES_PER_WORD          sizeof(void *)
 #define REDZONE_ALIGN           max(BYTES_PER_WORD, __alignof__(unsigned long long))
 
 #ifndef cache_line_size
 #define cache_line_size()       L1_CACHE_BYTES
 #endif
 
 #ifndef ARCH_KMALLOC_MINALIGN
 /*
  * Enforce a minimum alignment for the kmalloc caches.
  * Usually, the kmalloc caches are cache_line_size() aligned, except when
  * DEBUG and FORCED_DEBUG are enabled, then they are BYTES_PER_WORD aligned.
  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
  * alignment larger than the alignment of a 64-bit integer.
  * ARCH_KMALLOC_MINALIGN allows that.
  * Note that increasing this value may disable some debug features.
  */
 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
 #endif
 
 #ifndef ARCH_SLAB_MINALIGN
 /*
  * Enforce a minimum alignment for all caches.
  * Intended for archs that get misalignment faults even for BYTES_PER_WORD
  * aligned buffers. Includes ARCH_KMALLOC_MINALIGN.
  * If possible: Do not enable this flag for CONFIG_DEBUG_SLAB, it disables
  * some debug features.
  */
 #define ARCH_SLAB_MINALIGN 0
 #endif
 
 #ifndef ARCH_KMALLOC_FLAGS
 #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
 #endif
 
 /* Legal flag mask for kmem_cache_create(). */
 #if DEBUG
 # define CREATE_MASK    (SLAB_RED_ZONE | \
                          SLAB_POISON | SLAB_HWCACHE_ALIGN | \
                          SLAB_CACHE_DMA | \
                          SLAB_STORE_USER | \
                          SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                          SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD)
 #else
 # define CREATE_MASK    (SLAB_HWCACHE_ALIGN | \
                          SLAB_CACHE_DMA | \
                          SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
                          SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD)
 #endif
 
 /*
  * kmem_bufctl_t:
  *
  * Bufctl's are used for linking objs within a slab
  * linked offsets.
  *
  * This implementation relies on "struct page" for locating the cache &
  * slab an object belongs to.
  * This allows the bufctl structure to be small (one int), but limits
  * the number of objects a slab (not a cache) can contain when off-slab
  * bufctls are used. The limit is the size of the largest general cache
  * that does not use off-slab slabs.
  * For 32bit archs with 4 kB pages, is this 56.
  * This is not serious, as it is only for large objects, when it is unwise
  * to have too many per slab.
  * Note: This limit can be raised by introducing a general cache whose size
  * is less than 512 (PAGE_SIZE<<3), but greater than 256.
  */
 
 typedef unsigned int kmem_bufctl_t;
 #define BUFCTL_END      (((kmem_bufctl_t)(~0U))-0)
 #define BUFCTL_FREE     (((kmem_bufctl_t)(~0U))-1)
 #define BUFCTL_ACTIVE   (((kmem_bufctl_t)(~0U))-2)
 #define SLAB_LIMIT      (((kmem_bufctl_t)(~0U))-3)
 
 /*
  * struct slab
  *
  * Manages the objs in a slab. Placed either at the beginning of mem allocated
  * for a slab, or allocated from an general cache.
  * Slabs are chained into three list: fully used, partial, fully free slabs.
  */
 struct slab {
         struct list_head list;
         unsigned long colouroff;
         void *s_mem;            /* including colour offset */
         unsigned int inuse;     /* num of objs active in slab */
         kmem_bufctl_t free;
         unsigned short nodeid;
 };
 
 /*
  * struct slab_rcu
  *
  * slab_destroy on a SLAB_DESTROY_BY_RCU cache uses this structure to
  * arrange for kmem_freepages to be called via RCU.  This is useful if
  * we need to approach a kernel structure obliquely, from its address
  * obtained without the usual locking.  We can lock the structure to
  * stabilize it and check it's still at the given address, only if we
  * can be sure that the memory has not been meanwhile reused for some
  * other kind of object (which our subsystem's lock might corrupt).
  *
  * rcu_read_lock before reading the address, then rcu_read_unlock after
  * taking the spinlock within the structure expected at that address.
  *
  * We assume struct slab_rcu can overlay struct slab when destroying.
  */
 struct slab_rcu {
         struct rcu_head head;
         struct kmem_cache *cachep;
         void *addr;
 };
 
 /*
  * struct array_cache
  *
  * Purpose:
  * - LIFO ordering, to hand out cache-warm objects from _alloc
  * - reduce the number of linked list operations
  * - reduce spinlock operations
  *
  * The limit is stored in the per-cpu structure to reduce the data cache
  * footprint.
  *
  */
 struct array_cache {
         unsigned int avail;
         unsigned int limit;
         unsigned int batchcount;
         unsigned int touched;
         spinlock_t lock;
         void *entry[];  /*
                          * Must have this definition in here for the proper
                          * alignment of array_cache. Also simplifies accessing
                          * the entries.
                          */
 };
 
 /*
  * bootstrap: The caches do not work without cpuarrays anymore, but the
  * cpuarrays are allocated from the generic caches...
  */
 #define BOOT_CPUCACHE_ENTRIES   1
 struct arraycache_init {
         struct array_cache cache;
         void *entries[BOOT_CPUCACHE_ENTRIES];
 };
 
 /*
  * The slab lists for all objects.
  */
 struct kmem_list3 {
         struct list_head slabs_partial; /* partial list first, better asm code */
         struct list_head slabs_full;
         struct list_head slabs_free;
         unsigned long free_objects;
         unsigned int free_limit;
         unsigned int colour_next;       /* Per-node cache coloring */
         spinlock_t list_lock;
         struct array_cache *shared;     /* shared per node */
         struct array_cache **alien;     /* on other nodes */
         unsigned long next_reap;        /* updated without locking */
         int free_touched;               /* updated without locking */
 };
 
 /*
  * Need this for bootstrapping a per node allocator.
  */
 #define NUM_INIT_LISTS (3 * MAX_NUMNODES)
 struct kmem_list3 __initdata initkmem_list3[NUM_INIT_LISTS];
 #define CACHE_CACHE 0
 #define SIZE_AC MAX_NUMNODES
 #define SIZE_L3 (2 * MAX_NUMNODES)
 
 static int drain_freelist(struct kmem_cache *cache,
                         struct kmem_list3 *l3, int tofree);
 static void free_block(struct kmem_cache *cachep, void **objpp, int len,
                         int node, int *this_cpu);
 static int enable_cpucache(struct kmem_cache *cachep);
 static void cache_reap(struct work_struct *unused);
 
 /*
  * This function must be completely optimized away if a constant is passed to
  * it.  Mostly the same as what is in linux/slab.h except it returns an index.
  */
 static __always_inline int index_of(const size_t size)
 {
         extern void __bad_size(void);
 
         if (__builtin_constant_p(size)) {
                 int i = 0;
 
 #define CACHE(x) \
         if (size <=x) \
                 return i; \
         else \
                 i++;
 #include <linux/kmalloc_sizes.h>
 #undef CACHE
                 __bad_size();
         } else
                 __bad_size();
         return 0;
 }
 
 static int slab_early_init = 1;
 
 #define INDEX_AC index_of(sizeof(struct arraycache_init))
 #define INDEX_L3 index_of(sizeof(struct kmem_list3))
 
 static void kmem_list3_init(struct kmem_list3 *parent)
 {
         INIT_LIST_HEAD(&parent->slabs_full);
         INIT_LIST_HEAD(&parent->slabs_partial);
         INIT_LIST_HEAD(&parent->slabs_free);
         parent->shared = NULL;
         parent->alien = NULL;
         parent->colour_next = 0;
         spin_lock_init(&parent->list_lock);
         parent->free_objects = 0;
         parent->free_touched = 0;
 }
 
 #define MAKE_LIST(cachep, listp, slab, nodeid)                          \
         do {                                                            \
                 INIT_LIST_HEAD(listp);                                  \
                 list_splice(&(cachep->nodelists[nodeid]->slab), listp); \
         } while (0)
 
 #define MAKE_ALL_LISTS(cachep, ptr, nodeid)                             \
         do {                                                            \
         MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);  \
         MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
         MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);  \
         } while (0)
 
 /*
  * struct kmem_cache
  *
  * manages a cache.
  */
 
 struct kmem_cache {
 /* 1) per-cpu data, touched during every alloc/free */
         struct array_cache *array[NR_CPUS];
 /* 2) Cache tunables. Protected by cache_chain_mutex */
         unsigned int batchcount;
         unsigned int limit;
         unsigned int shared;
 
         unsigned int buffer_size;
         u32 reciprocal_buffer_size;
 /* 3) touched by every alloc & free from the backend */
 
         unsigned int flags;             /* constant flags */
         unsigned int num;               /* # of objs per slab */
 
 /* 4) cache_grow/shrink */
         /* order of pgs per slab (2^n) */
         unsigned int gfporder;
 
         /* force GFP flags, e.g. GFP_DMA */
         gfp_t gfpflags;
 
         size_t colour;                  /* cache colouring range */
         unsigned int colour_off;        /* colour offset */
         struct kmem_cache *slabp_cache;
         unsigned int slab_size;
         unsigned int dflags;            /* dynamic flags */
 
         /* constructor func */
         void (*ctor)(struct kmem_cache *, void *);
 
 /* 5) cache creation/removal */
         const char *name;
         struct list_head next;
 
 /* 6) statistics */
 #if STATS
         unsigned long num_active;
         unsigned long num_allocations;
         unsigned long high_mark;
         unsigned long grown;
         unsigned long reaped;
         unsigned long errors;
         unsigned long max_freeable;
         unsigned long node_allocs;
         unsigned long node_frees;
         unsigned long node_overflow;
         atomic_t allochit;
         atomic_t allocmiss;
         atomic_t freehit;
         atomic_t freemiss;
 #endif
 #if DEBUG
         /*
          * If debugging is enabled, then the allocator can add additional
          * fields and/or padding to every object. buffer_size contains the total
          * object size including these internal fields, the following two
          * variables contain the offset to the user object and its size.
          */
         int obj_offset;
         int obj_size;
 #endif
         /*
          * We put nodelists[] at the end of kmem_cache, because we want to size
          * this array to nr_node_ids slots instead of MAX_NUMNODES
          * (see kmem_cache_init())
          * We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
          * is statically defined, so we reserve the max number of nodes.
          */
         struct kmem_list3 *nodelists[MAX_NUMNODES];
         /*
          * Do not add fields after nodelists[]
          */
 };
 
 #define CFLGS_OFF_SLAB          (0x80000000UL)
 #define OFF_SLAB(x)     ((x)->flags & CFLGS_OFF_SLAB)
 
 #define BATCHREFILL_LIMIT       16
 /*
  * Optimization question: fewer reaps means less probability for unnessary
  * cpucache drain/refill cycles.
  *
  * OTOH the cpuarrays can contain lots of objects,
  * which could lock up otherwise freeable slabs.
  */
 #define REAPTIMEOUT_CPUC        (2*HZ)
 #define REAPTIMEOUT_LIST3       (4*HZ)
 
 #if STATS
 #define STATS_INC_ACTIVE(x)     ((x)->num_active++)
 #define STATS_DEC_ACTIVE(x)     ((x)->num_active--)
 #define STATS_INC_ALLOCED(x)    ((x)->num_allocations++)
 #define STATS_INC_GROWN(x)      ((x)->grown++)
 #define STATS_ADD_REAPED(x,y)   ((x)->reaped += (y))
 #define STATS_SET_HIGH(x)                                               \
         do {                                                            \
                 if ((x)->num_active > (x)->high_mark)                   \
                         (x)->high_mark = (x)->num_active;               \
         } while (0)
 #define STATS_INC_ERR(x)        ((x)->errors++)
 #define STATS_INC_NODEALLOCS(x) ((x)->node_allocs++)
 #define STATS_INC_NODEFREES(x)  ((x)->node_frees++)
 #define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
 #define STATS_SET_FREEABLE(x, i)                                        \
         do {                                                            \
                 if ((x)->max_freeable < i)                              \
                         (x)->max_freeable = i;                          \
         } while (0)
 #define STATS_INC_ALLOCHIT(x)   atomic_inc(&(x)->allochit)
 #define STATS_INC_ALLOCMISS(x)  atomic_inc(&(x)->allocmiss)
 #define STATS_INC_FREEHIT(x)    atomic_inc(&(x)->freehit)
 #define STATS_INC_FREEMISS(x)   atomic_inc(&(x)->freemiss)
 #else
 #define STATS_INC_ACTIVE(x)     do { } while (0)
 #define STATS_DEC_ACTIVE(x)     do { } while (0)
 #define STATS_INC_ALLOCED(x)    do { } while (0)
 #define STATS_INC_GROWN(x)      do { } while (0)
 #define STATS_ADD_REAPED(x,y)   do { } while (0)
 #define STATS_SET_HIGH(x)       do { } while (0)
 #define STATS_INC_ERR(x)        do { } while (0)
 #define STATS_INC_NODEALLOCS(x) do { } while (0)
 #define STATS_INC_NODEFREES(x)  do { } while (0)
 #define STATS_INC_ACOVERFLOW(x)   do { } while (0)
 #define STATS_SET_FREEABLE(x, i) do { } while (0)
 #define STATS_INC_ALLOCHIT(x)   do { } while (0)
 #define STATS_INC_ALLOCMISS(x)  do { } while (0)
 #define STATS_INC_FREEHIT(x)    do { } while (0)
 #define STATS_INC_FREEMISS(x)   do { } while (0)
 #endif
 
 #if DEBUG
 
 /*
  * memory layout of objects:
  * 0            : objp
  * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
  *              the end of an object is aligned with the end of the real
  *              allocation. Catches writes behind the end of the allocation.
  * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
  *              redzone word.
  * cachep->obj_offset: The real object.
  * cachep->buffer_size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
  * cachep->buffer_size - 1* BYTES_PER_WORD: last caller address
  *                                      [BYTES_PER_WORD long]
  */
 static int obj_offset(struct kmem_cache *cachep)
 {
         return cachep->obj_offset;
 }
 
 static int obj_size(struct kmem_cache *cachep)
 {
         return cachep->obj_size;
 }
 
 static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
         return (unsigned long long*) (objp + obj_offset(cachep) -
                                       sizeof(unsigned long long));
 }
 
 static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
         if (cachep->flags & SLAB_STORE_USER)
                 return (unsigned long long *)(objp + cachep->buffer_size -
                                               sizeof(unsigned long long) -
                                               REDZONE_ALIGN);
         return (unsigned long long *) (objp + cachep->buffer_size -
                                        sizeof(unsigned long long));
 }
 
 static void **dbg_userword(struct kmem_cache *cachep, void *objp)
 {
         BUG_ON(!(cachep->flags & SLAB_STORE_USER));
         return (void **)(objp + cachep->buffer_size - BYTES_PER_WORD);
 }
 
 #else
 
 #define obj_offset(x)                   0
 #define obj_size(cachep)                (cachep->buffer_size)
 #define dbg_redzone1(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
 #define dbg_redzone2(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
 #define dbg_userword(cachep, objp)      ({BUG(); (void **)NULL;})
 
 #endif
 
 /*
  * Do not go above this order unless 0 objects fit into the slab.
  */
 #define BREAK_GFP_ORDER_HI      1
 #define BREAK_GFP_ORDER_LO      0
 static int slab_break_gfp_order = BREAK_GFP_ORDER_LO;
 
 /*
  * Functions for storing/retrieving the cachep and or slab from the page
  * allocator.  These are used to find the slab an obj belongs to.  With kfree(),
  * these are used to find the cache which an obj belongs to.
  */
 static inline void page_set_cache(struct page *page, struct kmem_cache *cache)
 {
         page->lru.next = (struct list_head *)cache;
 }
 
 static inline struct kmem_cache *page_get_cache(struct page *page)
 {
         page = compound_head(page);
         BUG_ON(!PageSlab(page));
         return (struct kmem_cache *)page->lru.next;
 }
 
 static inline void page_set_slab(struct page *page, struct slab *slab)
 {
         page->lru.prev = (struct list_head *)slab;
 }
 
 static inline struct slab *page_get_slab(struct page *page)
 {
         BUG_ON(!PageSlab(page));
         return (struct slab *)page->lru.prev;
 }
 
 static inline struct kmem_cache *virt_to_cache(const void *obj)
 {
         struct page *page = virt_to_head_page(obj);
         return page_get_cache(page);
 }
 
 static inline struct slab *virt_to_slab(const void *obj)
 {
         struct page *page = virt_to_head_page(obj);
         return page_get_slab(page);
 }
 
 static inline void *index_to_obj(struct kmem_cache *cache, struct slab *slab,
                                  unsigned int idx)
 {
         return slab->s_mem + cache->buffer_size * idx;
 }
 
 /*
  * We want to avoid an expensive divide : (offset / cache->buffer_size)
  *   Using the fact that buffer_size is a constant for a particular cache,
  *   we can replace (offset / cache->buffer_size) by
  *   reciprocal_divide(offset, cache->reciprocal_buffer_size)
  */
 static inline unsigned int obj_to_index(const struct kmem_cache *cache,
                                         const struct slab *slab, void *obj)
 {
         u32 offset = (obj - slab->s_mem);
         return reciprocal_divide(offset, cache->reciprocal_buffer_size);
 }
 
 /*
  * These are the default caches for kmalloc. Custom caches can have other sizes.
  */
 struct cache_sizes malloc_sizes[] = {
 #define CACHE(x) { .cs_size = (x) },
 #include <linux/kmalloc_sizes.h>
         CACHE(ULONG_MAX)
 #undef CACHE
 };
 EXPORT_SYMBOL(malloc_sizes);
 
 /* Must match cache_sizes above. Out of line to keep cache footprint low. */
 struct cache_names {
         char *name;
         char *name_dma;
 };
 
 static struct cache_names __initdata cache_names[] = {
 #define CACHE(x) { .name = "size-" #x, .name_dma = "size-" #x "(DMA)" },
 #include <linux/kmalloc_sizes.h>
         {NULL,}
 #undef CACHE
 };
 
 static struct arraycache_init initarray_cache __initdata =
     { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
 static struct arraycache_init initarray_generic =
     { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
 
 /* internal cache of cache description objs */
 static struct kmem_cache cache_cache = {
         .batchcount = 1,
         .limit = BOOT_CPUCACHE_ENTRIES,
         .shared = 1,
         .buffer_size = sizeof(struct kmem_cache),
         .name = "kmem_cache",
 };
 
 #define BAD_ALIEN_MAGIC 0x01020304ul
 
 #ifdef CONFIG_LOCKDEP
 
 /*
  * Slab sometimes uses the kmalloc slabs to store the slab headers
  * for other slabs "off slab".
  * The locking for this is tricky in that it nests within the locks
  * of all other slabs in a few places; to deal with this special
  * locking we put on-slab caches into a separate lock-class.
  *
  * We set lock class for alien array caches which are up during init.
  * The lock annotation will be lost if all cpus of a node goes down and
  * then comes back up during hotplug
  */
 static struct lock_class_key on_slab_l3_key;
 static struct lock_class_key on_slab_alc_key;
 
 static inline void init_lock_keys(void)
 
 {
         int q;
         struct cache_sizes *s = malloc_sizes;
 
         while (s->cs_size != ULONG_MAX) {
                 for_each_node(q) {
                         struct array_cache **alc;
                         int r;
                         struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];
                         if (!l3 || OFF_SLAB(s->cs_cachep))
                                 continue;
                         lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
                         alc = l3->alien;
                         /*
                          * FIXME: This check for BAD_ALIEN_MAGIC
                          * should go away when common slab code is taught to
                          * work even without alien caches.
                          * Currently, non NUMA code returns BAD_ALIEN_MAGIC
                          * for alloc_alien_cache,
                          */
                         if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
                                 continue;
                         for_each_node(r) {
                                 if (alc[r])
                                         lockdep_set_class(&alc[r]->lock,
                                              &on_slab_alc_key);
                         }
                 }
                 s++;
         }
 }
 #else
 static inline void init_lock_keys(void)
 {
 }
 #endif
 
 /*
  * Guard access to the cache-chain.
  */
 static DEFINE_MUTEX(cache_chain_mutex);
 static struct list_head cache_chain;
 
 /*
  * chicken and egg problem: delay the per-cpu array allocation
  * until the general caches are up.
  */
 static enum {
         NONE,
         PARTIAL_AC,
         PARTIAL_L3,
         FULL
 } g_cpucache_up;
 
 /*
  * used by boot code to determine if it can use slab based allocator
  */
 int slab_is_available(void)
 {
         return g_cpucache_up == FULL;
 }
 
 static DEFINE_PER_CPU(struct delayed_work, reap_work);
 
 static inline struct array_cache *
 cpu_cache_get(struct kmem_cache *cachep, int this_cpu)
 {
         return cachep->array[this_cpu];
 }
 
 static inline struct kmem_cache *__find_general_cachep(size_t size,
                                                         gfp_t gfpflags)
 {
         struct cache_sizes *csizep = malloc_sizes;
 
 #if DEBUG
         /* This happens if someone tries to call
          * kmem_cache_create(), or __kmalloc(), before
          * the generic caches are initialized.
          */
         BUG_ON(malloc_sizes[INDEX_AC].cs_cachep == NULL);
 #endif
         if (!size)
                 return ZERO_SIZE_PTR;
 
         while (size > csizep->cs_size)
                 csizep++;
 
         /*
          * Really subtle: The last entry with cs->cs_size==ULONG_MAX
          * has cs_{dma,}cachep==NULL. Thus no special case
          * for large kmalloc calls required.
          */
 #ifdef CONFIG_ZONE_DMA
         if (unlikely(gfpflags & GFP_DMA))
                 return csizep->cs_dmacachep;
 #endif
         return csizep->cs_cachep;
 }
 
 static struct kmem_cache *kmem_find_general_cachep(size_t size, gfp_t gfpflags)
 {
         return __find_general_cachep(size, gfpflags);
 }
 
 static size_t slab_mgmt_size(size_t nr_objs, size_t align)
 {
         return ALIGN(sizeof(struct slab)+nr_objs*sizeof(kmem_bufctl_t), align);
 }
 
 /*
  * Calculate the number of objects and left-over bytes for a given buffer size.
  */
 static void cache_estimate(unsigned long gfporder, size_t buffer_size,
                            size_t align, int flags, size_t *left_over,
                            unsigned int *num)
 {
         int nr_objs;
         size_t mgmt_size;
         size_t slab_size = PAGE_SIZE << gfporder;
 
         /*
          * The slab management structure can be either off the slab or
          * on it. For the latter case, the memory allocated for a
          * slab is used for:
          *
          * - The struct slab
          * - One kmem_bufctl_t for each object
          * - Padding to respect alignment of @align
          * - @buffer_size bytes for each object
          *
          * If the slab management structure is off the slab, then the
          * alignment will already be calculated into the size. Because
          * the slabs are all pages aligned, the objects will be at the
          * correct alignment when allocated.
          */
         if (flags & CFLGS_OFF_SLAB) {
                 mgmt_size = 0;
                 nr_objs = slab_size / buffer_size;
 
                 if (nr_objs > SLAB_LIMIT)
                         nr_objs = SLAB_LIMIT;
         } else {
                 /*
                  * Ignore padding for the initial guess. The padding
                  * is at most @align-1 bytes, and @buffer_size is at
                  * least @align. In the worst case, this result will
                  * be one greater than the number of objects that fit
                  * into the memory allocation when taking the padding
                  * into account.
                  */
                 nr_objs = (slab_size - sizeof(struct slab)) /
                           (buffer_size + sizeof(kmem_bufctl_t));
 
                 /*
                  * This calculated number will be either the right
                  * amount, or one greater than what we want.
                  */
                 if (slab_mgmt_size(nr_objs, align) + nr_objs*buffer_size
                        > slab_size)
                         nr_objs--;
 
                 if (nr_objs > SLAB_LIMIT)
                         nr_objs = SLAB_LIMIT;
 
                 mgmt_size = slab_mgmt_size(nr_objs, align);
         }
         *num = nr_objs;
         *left_over = slab_size - nr_objs*buffer_size - mgmt_size;
 }
 
 #define slab_error(cachep, msg) __slab_error(__FUNCTION__, cachep, msg)
 
 static void __slab_error(const char *function, struct kmem_cache *cachep,
                         char *msg)
 {
         printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
                function, cachep->name, msg);
         dump_stack();
 }
 
 /*
  * By default on NUMA we use alien caches to stage the freeing of
  * objects allocated from other nodes. This causes massive memory
  * inefficiencies when using fake NUMA setup to split memory into a
  * large number of small nodes, so it can be disabled on the command
  * line
   */
 
 static int use_alien_caches __read_mostly = 1;
 static int numa_platform __read_mostly = 1;
 static int __init noaliencache_setup(char *s)
 {
         use_alien_caches = 0;
         return 1;
 }
 __setup("noaliencache", noaliencache_setup);
 
 #ifdef CONFIG_NUMA
 /*
  * Special reaping functions for NUMA systems called from cache_reap().
  * These take care of doing round robin flushing of alien caches (containing
  * objects freed on different nodes from which they were allocated) and the
  * flushing of remote pcps by calling drain_node_pages.
  */
 static DEFINE_PER_CPU(unsigned long, reap_node);
 
 static void init_reap_node(int cpu)
 {
         int node;
 
         node = next_node(cpu_to_node(cpu), node_online_map);
         if (node == MAX_NUMNODES)
                 node = first_node(node_online_map);
 
         per_cpu(reap_node, cpu) = node;
 }
 
 static void next_reap_node(void)
 {
         int node = __get_cpu_var(reap_node);
 
         node = next_node(node, node_online_map);
         if (unlikely(node >= MAX_NUMNODES))
                 node = first_node(node_online_map);
         __get_cpu_var(reap_node) = node;
 }
 
 #else
 #define init_reap_node(cpu) do { } while (0)
 #define next_reap_node(void) do { } while (0)
 #endif
 
 /*
  * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
  * via the workqueue/eventd.
  * Add the CPU number into the expiration time to minimize the possibility of
  * the CPUs getting into lockstep and contending for the global cache chain
  * lock.
  */
 static void __cpuinit start_cpu_timer(int cpu)
 {
         struct delayed_work *reap_work = &per_cpu(reap_work, cpu);
 
         /*
          * When this gets called from do_initcalls via cpucache_init(),
          * init_workqueues() has already run, so keventd will be setup
          * at that time.
          */
         if (keventd_up() && reap_work->work.func == NULL) {
                 init_reap_node(cpu);
                 INIT_DELAYED_WORK(reap_work, cache_reap);
                 schedule_delayed_work_on(cpu, reap_work,
                                         __round_jiffies_relative(HZ, cpu));
         }
 }
 
 static struct array_cache *alloc_arraycache(int node, int entries,
                                             int batchcount)
 {
         int memsize = sizeof(void *) * entries + sizeof(struct array_cache);
         struct array_cache *nc = NULL;
 
         nc = kmalloc_node(memsize, GFP_KERNEL, node);
         if (nc) {
                 nc->avail = 0;
                 nc->limit = entries;
                 nc->batchcount = batchcount;
                 nc->touched = 0;
                 spin_lock_init(&nc->lock);
         }
         return nc;
 }
 
 /*
  * Transfer objects in one arraycache to another.
  * Locking must be handled by the caller.
  *
  * Return the number of entries transferred.
  */
 static int transfer_objects(struct array_cache *to,
                 struct array_cache *from, unsigned int max)
 {
         /* Figure out how many entries to transfer */
         int nr = min(min(from->avail, max), to->limit - to->avail);
 
         if (!nr)
                 return 0;
 
         memcpy(to->entry + to->avail, from->entry + from->avail -nr,
                         sizeof(void *) *nr);
 
         from->avail -= nr;
         to->avail += nr;
         to->touched = 1;
         return nr;
 }
 
 #ifndef CONFIG_NUMA
 
 #define drain_alien_cache(cachep, alien) do { } while (0)
 #define reap_alien(cachep, l3, this_cpu) 0
 
 static inline struct array_cache **alloc_alien_cache(int node, int limit)
 {
         return (struct array_cache **)BAD_ALIEN_MAGIC;
 }
 
 static inline void free_alien_cache(struct array_cache **ac_ptr)
 {
 }
 
 static inline int
 cache_free_alien(struct kmem_cache *cachep, void *objp, int *this_cpu)
 {
         return 0;
 }
 
 static inline void *alternate_node_alloc(struct kmem_cache *cachep,
                 gfp_t flags, int *this_cpu)
 {
         return NULL;
 }
 
 static inline void *____cache_alloc_node(struct kmem_cache *cachep,
                  gfp_t flags, int nodeid, int *this_cpu)
 {
         return NULL;
 }
 
 #else   /* CONFIG_NUMA */
 
 static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
                                 int nodeid, int *this_cpu);
 static void *alternate_node_alloc(struct kmem_cache *, gfp_t, int *);
 
 static struct array_cache **alloc_alien_cache(int node, int limit)
 {
         struct array_cache **ac_ptr;
         int memsize = sizeof(void *) * nr_node_ids;
         int i;
 
         if (limit > 1)
                 limit = 12;
         ac_ptr = kmalloc_node(memsize, GFP_KERNEL, node);
         if (ac_ptr) {
                 for_each_node(i) {
                         if (i == node || !node_online(i)) {
                                 ac_ptr[i] = NULL;
                                 continue;
                         }
                         ac_ptr[i] = alloc_arraycache(node, limit, 0xbaadf00d);
                         if (!ac_ptr[i]) {
                                 for (i--; i >= 0; i--)
                                         kfree(ac_ptr[i]);
                                 kfree(ac_ptr);
                                 return NULL;
                         }
                 }
         }
         return ac_ptr;
 }
 
 static void free_alien_cache(struct array_cache **ac_ptr)
 {
         int i;
 
         if (!ac_ptr)
                 return;
         for_each_node(i)
             kfree(ac_ptr[i]);
         kfree(ac_ptr);
 }
 
 static void __drain_alien_cache(struct kmem_cache *cachep,
                                 struct array_cache *ac, int node,
                                 int *this_cpu)
 {
         struct kmem_list3 *rl3 = cachep->nodelists[node];
 
         if (ac->avail) {
                 spin_lock(&rl3->list_lock);
                 /*
                  * Stuff objects into the remote nodes shared array first.
                  * That way we could avoid the overhead of putting the objects
                  * into the free lists and getting them back later.
                  */
                 if (rl3->shared)
                         transfer_objects(rl3->shared, ac, ac->limit);
 
                 free_block(cachep, ac->entry, ac->avail, node, this_cpu);
                 ac->avail = 0;
                 spin_unlock(&rl3->list_lock);
         }
 }
 
 /*
  * Called from cache_reap() to regularly drain alien caches round robin.
  */
 static int
 reap_alien(struct kmem_cache *cachep, struct kmem_list3 *l3, int *this_cpu)
 {
         int node = per_cpu(reap_node, *this_cpu);
 
         if (l3->alien) {
                 struct array_cache *ac = l3->alien[node];
 
                 if (ac && ac->avail && spin_trylock_irq(&ac->lock)) {
                         __drain_alien_cache(cachep, ac, node, this_cpu);
                         spin_unlock_irq(&ac->lock);
                         return 1;
                 }
         }
         return 0;
 }
 
 static void drain_alien_cache(struct kmem_cache *cachep,
                                 struct array_cache **alien)
 {
         int i = 0, this_cpu;
         struct array_cache *ac;
         unsigned long flags;
 
         for_each_online_node(i) {
                 ac = alien[i];
                 if (ac) {
                         slab_spin_lock_irqsave(&ac->lock, flags, this_cpu);
                         __drain_alien_cache(cachep, ac, i, &this_cpu);
                         slab_spin_unlock_irqrestore(&ac->lock, flags, this_cpu);
                 }
         }
 }
 
 static inline int
 cache_free_alien(struct kmem_cache *cachep, void *objp, int *this_cpu)
 {
         struct slab *slabp = virt_to_slab(objp);
         int nodeid = slabp->nodeid;
         struct kmem_list3 *l3;
         struct array_cache *alien = NULL;
         int node;
 
         node = cpu_to_node(*this_cpu);
 
         /*
          * Make sure we are not freeing a object from another node to the array
          * cache on this cpu.
          */
         if (likely(slabp->nodeid == node))
                 return 0;
 
         l3 = cachep->nodelists[node];
         STATS_INC_NODEFREES(cachep);
         if (l3->alien && l3->alien[nodeid]) {
                 alien = l3->alien[nodeid];
                 spin_lock(&alien->lock);
                 if (unlikely(alien->avail == alien->limit)) {
                         STATS_INC_ACOVERFLOW(cachep);
                         __drain_alien_cache(cachep, alien, nodeid, this_cpu);
                 }
                 alien->entry[alien->avail++] = objp;
                 spin_unlock(&alien->lock);
         } else {
                 spin_lock(&(cachep->nodelists[nodeid])->list_lock);
                 free_block(cachep, &objp, 1, nodeid, this_cpu);
                 spin_unlock(&(cachep->nodelists[nodeid])->list_lock);
         }
         return 1;
 }
 #endif
 
 static void __cpuinit cpuup_canceled(long cpu)
 {
         struct kmem_cache *cachep;
         struct kmem_list3 *l3 = NULL;
         int node = cpu_to_node(cpu);
 
         list_for_each_entry(cachep, &cache_chain, next) {
                 struct array_cache *nc;
                 struct array_cache *shared;
                 struct array_cache **alien;
                 int this_cpu;
                 cpumask_t mask;
 
                 mask = node_to_cpumask(node);
                 /* cpu is dead; no one can alloc from it. */
                 nc = cachep->array[cpu];
                 cachep->array[cpu] = NULL;
                 l3 = cachep->nodelists[node];
 
                 if (!l3)
                         goto free_array_cache;
 
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
 
                 /* Free limit for this kmem_list3 */
                 l3->free_limit -= cachep->batchcount;
                 if (nc)
                         free_block(cachep, nc->entry, nc->avail, node,
                                    &this_cpu);
 
                 if (!cpus_empty(mask)) {
                         slab_spin_unlock_irq(&l3->list_lock,
                                              this_cpu);
                         goto free_array_cache;
                 }
 
                 shared = l3->shared;
                 if (shared) {
                         free_block(cachep, shared->entry,
                                    shared->avail, node, &this_cpu);
                         l3->shared = NULL;
                 }
 
                 alien = l3->alien;
                 l3->alien = NULL;
 
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
 
                 kfree(shared);
                 if (alien) {
                         drain_alien_cache(cachep, alien);
                         free_alien_cache(alien);
                 }
 free_array_cache:
                 kfree(nc);
         }
         /*
          * In the previous loop, all the objects were freed to
          * the respective cache's slabs,  now we can go ahead and
          * shrink each nodelist to its limit.
          */
         list_for_each_entry(cachep, &cache_chain, next) {
                 l3 = cachep->nodelists[node];
                 if (!l3)
                         continue;
                 drain_freelist(cachep, l3, l3->free_objects);
         }
 }
 
 static int __cpuinit cpuup_prepare(long cpu)
 {
         struct kmem_cache *cachep;
         struct kmem_list3 *l3 = NULL;
         int node = cpu_to_node(cpu);
         const int memsize = sizeof(struct kmem_list3);
         int this_cpu;
 
         /*
          * We need to do this right in the beginning since
          * alloc_arraycache's are going to use this list.
          * kmalloc_node allows us to add the slab to the right
          * kmem_list3 and not this cpu's kmem_list3
          */
 
         list_for_each_entry(cachep, &cache_chain, next) {
                 /*
                  * Set up the size64 kmemlist for cpu before we can
                  * begin anything. Make sure some other cpu on this
                  * node has not already allocated this
                  */
                 if (!cachep->nodelists[node]) {
                         l3 = kmalloc_node(memsize, GFP_KERNEL, node);
                         if (!l3)
                                 goto bad;
                         kmem_list3_init(l3);
                         l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
                             ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
 
                         /*
                          * The l3s don't come and go as CPUs come and
                          * go.  cache_chain_mutex is sufficient
                          * protection here.
                          */
                         cachep->nodelists[node] = l3;
                 }
 
                 slab_spin_lock_irq(&cachep->nodelists[node]->list_lock, this_cpu);
                 cachep->nodelists[node]->free_limit =
                         (1 + nr_cpus_node(node)) *
                         cachep->batchcount + cachep->num;
                 slab_spin_unlock_irq(&cachep->nodelists[node]->list_lock, this_cpu);
         }
 
         /*
          * Now we can go ahead with allocating the shared arrays and
          * array caches
          */
         list_for_each_entry(cachep, &cache_chain, next) {
                 struct array_cache *nc;
                 struct array_cache *shared = NULL;
                 struct array_cache **alien = NULL;
 
                 nc = alloc_arraycache(node, cachep->limit,
                                         cachep->batchcount);
                 if (!nc)
                         goto bad;
                 if (cachep->shared) {
                         shared = alloc_arraycache(node,
                                 cachep->shared * cachep->batchcount,
                                 0xbaadf00d);
                         if (!shared) {
                                 kfree(nc);
                                 goto bad;
                         }
                 }
                 if (use_alien_caches) {
                         alien = alloc_alien_cache(node, cachep->limit);
                         if (!alien) {
                                 kfree(shared);
                                 kfree(nc);
                                 goto bad;
                         }
                 }
                 cachep->array[cpu] = nc;
                 l3 = cachep->nodelists[node];
                 BUG_ON(!l3);
 
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
                 if (!l3->shared) {
                         /*
                          * We are serialised from CPU_DEAD or
                          * CPU_UP_CANCELLED by the cpucontrol lock
                          */
                         l3->shared = shared;
                         shared = NULL;
                 }
 #ifdef CONFIG_NUMA
                 if (!l3->alien) {
                         l3->alien = alien;
                         alien = NULL;
                 }
 #endif
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
                 kfree(shared);
                 free_alien_cache(alien);
         }
         return 0;
 bad:
         cpuup_canceled(cpu);
         return -ENOMEM;
 }
 
 static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                                     unsigned long action, void *hcpu)
 {
         long cpu = (long)hcpu;
         int err = 0;
 
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
                 mutex_lock(&cache_chain_mutex);
                 err = cpuup_prepare(cpu);
                 mutex_unlock(&cache_chain_mutex);
                 break;
         case CPU_ONLINE:
         case CPU_ONLINE_FROZEN:
                 start_cpu_timer(cpu);
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
         case CPU_DOWN_PREPARE:
         case CPU_DOWN_PREPARE_FROZEN:
                 /*
                  * Shutdown cache reaper. Note that the cache_chain_mutex is
                  * held so that if cache_reap() is invoked it cannot do
                  * anything expensive but will only modify reap_work
                  * and reschedule the timer.
                 */
                 cancel_rearming_delayed_work(&per_cpu(reap_work, cpu));
                 /* Now the cache_reaper is guaranteed to be not running. */
                 per_cpu(reap_work, cpu).work.func = NULL;
                 break;
         case CPU_DOWN_FAILED:
         case CPU_DOWN_FAILED_FROZEN:
                 start_cpu_timer(cpu);
                 break;
         case CPU_DEAD:
         case CPU_DEAD_FROZEN:
                 /*
                  * Even if all the cpus of a node are down, we don't free the
                  * kmem_list3 of any cache. This to avoid a race between
                  * cpu_down, and a kmalloc allocation from another cpu for
                  * memory from the node of the cpu going down.  The list3
                  * structure is usually allocated from kmem_cache_create() and
                  * gets destroyed at kmem_cache_destroy().
                  */
                 /* fall through */
 #endif
         case CPU_UP_CANCELED:
         case CPU_UP_CANCELED_FROZEN:
                 mutex_lock(&cache_chain_mutex);
                 cpuup_canceled(cpu);
                 mutex_unlock(&cache_chain_mutex);
                 break;
         }
         return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block __cpuinitdata cpucache_notifier = {
         &cpuup_callback, NULL, 0
 };
 
 /*
  * swap the static kmem_list3 with kmalloced memory
  */
 static void init_list(struct kmem_cache *cachep, struct kmem_list3 *list,
                         int nodeid)
 {
         struct kmem_list3 *ptr;
         int this_cpu;
 
         ptr = kmalloc_node(sizeof(struct kmem_list3), GFP_KERNEL, nodeid);
         BUG_ON(!ptr);
 
         WARN_ON(spin_is_locked(&list->list_lock));
         slab_irq_disable(this_cpu);
         memcpy(ptr, list, sizeof(struct kmem_list3));
         /*
          * Do not assume that spinlocks can be initialized via memcpy:
          */
         spin_lock_init(&ptr->list_lock);
 
         MAKE_ALL_LISTS(cachep, ptr, nodeid);
         cachep->nodelists[nodeid] = ptr;
         slab_irq_enable(this_cpu);
 }
 
 /*
  * For setting up all the kmem_list3s for cache whose buffer_size is same as
  * size of kmem_list3.
  */
 static void __init set_up_list3s(struct kmem_cache *cachep, int index)
 {
         int node;
 
         for_each_online_node(node) {
                 cachep->nodelists[node] = &initkmem_list3[index + node];
                 cachep->nodelists[node]->next_reap = jiffies +
                     REAPTIMEOUT_LIST3 +
                     ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
         }
 }
 
 /*
  * Initialisation.  Called after the page allocator have been initialised and
  * before smp_init().
  */
 void __init kmem_cache_init(void)
 {
         size_t left_over;
         struct cache_sizes *sizes;
         struct cache_names *names;
         int i;
         int order;
         int node;
 
         if (num_possible_nodes() == 1) {
                 use_alien_caches = 0;
                 numa_platform = 0;
         }
 
         for (i = 0; i < NUM_INIT_LISTS; i++) {
                 kmem_list3_init(&initkmem_list3[i]);
                 if (i < MAX_NUMNODES)
                         cache_cache.nodelists[i] = NULL;
         }
         set_up_list3s(&cache_cache, CACHE_CACHE);
 
         /*
          * Fragmentation resistance on low memory - only use bigger
          * page orders on machines with more than 32MB of memory.
          */
         if (num_physpages > (32 << 20) >> PAGE_SHIFT)
                 slab_break_gfp_order = BREAK_GFP_ORDER_HI;
 
         /* Bootstrap is tricky, because several objects are allocated
          * from caches that do not exist yet:
          * 1) initialize the cache_cache cache: it contains the struct
          *    kmem_cache structures of all caches, except cache_cache itself:
          *    cache_cache is statically allocated.
          *    Initially an __init data area is used for the head array and the
          *    kmem_list3 structures, it's replaced with a kmalloc allocated
          *    array at the end of the bootstrap.
          * 2) Create the first kmalloc cache.
          *    The struct kmem_cache for the new cache is allocated normally.
          *    An __init data area is used for the head array.
          * 3) Create the remaining kmalloc caches, with minimally sized
          *    head arrays.
          * 4) Replace the __init data head arrays for cache_cache and the first
          *    kmalloc cache with kmalloc allocated arrays.
          * 5) Replace the __init data for kmem_list3 for cache_cache and
          *    the other cache's with kmalloc allocated memory.
          * 6) Resize the head arrays of the kmalloc caches to their final sizes.
          */
 
         node = numa_node_id();
 
         /* 1) create the cache_cache */
         INIT_LIST_HEAD(&cache_chain);
         list_add(&cache_cache.next, &cache_chain);
         cache_cache.colour_off = cache_line_size();
         cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
         cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
 
         /*
          * struct kmem_cache size depends on nr_node_ids, which
          * can be less than MAX_NUMNODES.
          */
         cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
                                  nr_node_ids * sizeof(struct kmem_list3 *);
 #if DEBUG
         cache_cache.obj_size = cache_cache.buffer_size;
 #endif
         cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
                                         cache_line_size());
         cache_cache.reciprocal_buffer_size =
                 reciprocal_value(cache_cache.buffer_size);
 
         for (order = 0; order < MAX_ORDER; order++) {
                 cache_estimate(order, cache_cache.buffer_size,
                         cache_line_size(), 0, &left_over, &cache_cache.num);
                 if (cache_cache.num)
                         break;
         }
         BUG_ON(!cache_cache.num);
         cache_cache.gfporder = order;
         cache_cache.colour = left_over / cache_cache.colour_off;
         cache_cache.slab_size = ALIGN(cache_cache.num * sizeof(kmem_bufctl_t) +
                                       sizeof(struct slab), cache_line_size());
 
         /* 2+3) create the kmalloc caches */
         sizes = malloc_sizes;
         names = cache_names;
 
         /*
          * Initialize the caches that provide memory for the array cache and the
          * kmem_list3 structures first.  Without this, further allocations will
          * bug.
          */
 
         sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
                                         sizes[INDEX_AC].cs_size,
                                         ARCH_KMALLOC_MINALIGN,
                                         ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                         NULL);
 
         if (INDEX_AC != INDEX_L3) {
                 sizes[INDEX_L3].cs_cachep =
                         kmem_cache_create(names[INDEX_L3].name,
                                 sizes[INDEX_L3].cs_size,
                                 ARCH_KMALLOC_MINALIGN,
                                 ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                 NULL);
         }
 
         slab_early_init = 0;
 
         while (sizes->cs_size != ULONG_MAX) {
                 /*
                  * For performance, all the general caches are L1 aligned.
                  * This should be particularly beneficial on SMP boxes, as it
                  * eliminates "false sharing".
                  * Note for systems short on memory removing the alignment will
                  * allow tighter packing of the smaller caches.
                  */
                 if (!sizes->cs_cachep) {
                         sizes->cs_cachep = kmem_cache_create(names->name,
                                         sizes->cs_size,
                                         ARCH_KMALLOC_MINALIGN,
                                         ARCH_KMALLOC_FLAGS|SLAB_PANIC,
                                         NULL);
                 }
 #ifdef CONFIG_ZONE_DMA
                 sizes->cs_dmacachep = kmem_cache_create(
                                         names->name_dma,
                                         sizes->cs_size,
                                         ARCH_KMALLOC_MINALIGN,
                                         ARCH_KMALLOC_FLAGS|SLAB_CACHE_DMA|
                                                 SLAB_PANIC,
                                         NULL);
 #endif
                 sizes++;
                 names++;
         }
         /* 4) Replace the bootstrap head arrays */
         {
                 struct array_cache *ptr;
                 int this_cpu;
 
                 ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
 
                 slab_irq_disable(this_cpu);
                 BUG_ON(cpu_cache_get(&cache_cache, this_cpu) != &initarray_cache.cache);
                 memcpy(ptr, cpu_cache_get(&cache_cache, this_cpu),
                                 sizeof(struct arraycache_init));
                 /*
                  * Do not assume that spinlocks can be initialized via memcpy:
                  */
                 spin_lock_init(&ptr->lock);
                 cache_cache.array[this_cpu] = ptr;
                 slab_irq_enable(this_cpu);
 
                 ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
 
                 slab_irq_disable(this_cpu);
                 BUG_ON(cpu_cache_get(malloc_sizes[INDEX_AC].cs_cachep, this_cpu)
                                 != &initarray_generic.cache);
                 memcpy(ptr, cpu_cache_get(malloc_sizes[INDEX_AC].cs_cachep, this_cpu),
                                 sizeof(struct arraycache_init));
                 /*
                  * Do not assume that spinlocks can be initialized via memcpy:
                  */
                 spin_lock_init(&ptr->lock);
                 malloc_sizes[INDEX_AC].cs_cachep->array[this_cpu] = ptr;
                 slab_irq_enable(this_cpu);
         }
         /* 5) Replace the bootstrap kmem_list3's */
         {
                 int nid;
 
                 for_each_online_node(nid) {
                         init_list(&cache_cache, &initkmem_list3[CACHE_CACHE + nid], nid);
 
                         init_list(malloc_sizes[INDEX_AC].cs_cachep,
                                   &initkmem_list3[SIZE_AC + nid], nid);
 
                         if (INDEX_AC != INDEX_L3) {
                                 init_list(malloc_sizes[INDEX_L3].cs_cachep,
                                           &initkmem_list3[SIZE_L3 + nid], nid);
                         }
                 }
         }
 
         /* 6) resize the head arrays to their final sizes */
         {
                 struct kmem_cache *cachep;
                 mutex_lock(&cache_chain_mutex);
                 list_for_each_entry(cachep, &cache_chain, next)
                         if (enable_cpucache(cachep))
                                 BUG();
                 mutex_unlock(&cache_chain_mutex);
         }
 
         /* Annotate slab for lockdep -- annotate the malloc caches */
         init_lock_keys();
 
 
         /* Done! */
         g_cpucache_up = FULL;
 
         /*
          * Register a cpu startup notifier callback that initializes
          * cpu_cache_get for all new cpus
          */
         register_cpu_notifier(&cpucache_notifier);
 
         /*
          * The reap timers are started later, with a module init call: That part
          * of the kernel is not yet operational.
          */
 }
 
 static int __init cpucache_init(void)
 {
         int cpu;
 
         /*
          * Register the timers that return unneeded pages to the page allocator
          */
         for_each_online_cpu(cpu)
                 start_cpu_timer(cpu);
         return 0;
 }
 __initcall(cpucache_init);
 
 /*
  * Interface to system's page allocator. No need to hold the cache-lock.
  *
  * If we requested dmaable memory, we will get it. Even if we
  * did not request dmaable memory, we might get it, but that
  * would be relatively rare and ignorable.
  */
 static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
         struct page *page;
         int nr_pages;
         int i;
 
 #ifndef CONFIG_MMU
         /*
          * Nommu uses slab's for process anonymous memory allocations, and thus
          * requires __GFP_COMP to properly refcount higher order allocations
          */
         flags |= __GFP_COMP;
 #endif
 
         flags |= cachep->gfpflags;
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                 flags |= __GFP_RECLAIMABLE;
 
         page = alloc_pages_node(nodeid, flags, cachep->gfporder);
         if (!page)
                 return NULL;
 
         nr_pages = (1 << cachep->gfporder);
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                 add_zone_page_state(page_zone(page),
                         NR_SLAB_RECLAIMABLE, nr_pages);
         else
                 add_zone_page_state(page_zone(page),
                         NR_SLAB_UNRECLAIMABLE, nr_pages);
         for (i = 0; i < nr_pages; i++)
                 __SetPageSlab(page + i);
         return page_address(page);
 }
 
 /*
  * Interface to system's page release.
  */
 static void kmem_freepages(struct kmem_cache *cachep, void *addr)
 {
         unsigned long i = (1 << cachep->gfporder);
         struct page *page = virt_to_page(addr);
         const unsigned long nr_freed = i;
 
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
                 sub_zone_page_state(page_zone(page),
                                 NR_SLAB_RECLAIMABLE, nr_freed);
         else
                 sub_zone_page_state(page_zone(page),
                                 NR_SLAB_UNRECLAIMABLE, nr_freed);
         while (i--) {
                 BUG_ON(!PageSlab(page));
                 __ClearPageSlab(page);
                 page++;
         }
         if (current->reclaim_state)
                 current->reclaim_state->reclaimed_slab += nr_freed;
         free_pages((unsigned long)addr, cachep->gfporder);
 }
 
 static void kmem_rcu_free(struct rcu_head *head)
 {
         struct slab_rcu *slab_rcu = (struct slab_rcu *)head;
         struct kmem_cache *cachep = slab_rcu->cachep;
 
         kmem_freepages(cachep, slab_rcu->addr);
         if (OFF_SLAB(cachep))
                 kmem_cache_free(cachep->slabp_cache, slab_rcu);
 }
 
 #if DEBUG
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
                             unsigned long caller)
 {
         int size = obj_size(cachep);
 
         addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];
 
         if (size < 5 * sizeof(unsigned long))
                 return;
 
         *addr++ = 0x12345678;
         *addr++ = caller;
         *addr++ = raw_smp_processor_id();
         size -= 3 * sizeof(unsigned long);
         {
                 unsigned long *sptr = &caller;
                 unsigned long svalue;
 
                 while (!kstack_end(sptr)) {
                         svalue = *sptr++;
                         if (kernel_text_address(svalue)) {
                                 *addr++ = svalue;
                                 size -= sizeof(unsigned long);
                                 if (size <= sizeof(unsigned long))
                                         break;
                         }
                 }
 
         }
         *addr++ = 0x87654321;
 }
 #endif
 
 static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
 {
         int size = obj_size(cachep);
         addr = &((char *)addr)[obj_offset(cachep)];
 
         memset(addr, val, size);
         *(unsigned char *)(addr + size - 1) = POISON_END;
 }
 
 static void dump_line(char *data, int offset, int limit)
 {
         int i;
         unsigned char error = 0;
         int bad_count = 0;
 
         printk(KERN_ERR "%03x:", offset);
         for (i = 0; i < limit; i++) {
                 if (data[offset + i] != POISON_FREE) {
                         error = data[offset + i];
                         bad_count++;
                 }
                 printk(" %02x", (unsigned char)data[offset + i]);
         }
         printk("\n");
 
         if (bad_count == 1) {
                 error ^= POISON_FREE;
                 if (!(error & (error - 1))) {
                         printk(KERN_ERR "Single bit error detected. Probably "
                                         "bad RAM.\n");
 #ifdef CONFIG_X86
                         printk(KERN_ERR "Run memtest86+ or a similar memory "
                                         "test tool.\n");
 #else
                         printk(KERN_ERR "Run a memory test tool.\n");
 #endif
                 }
         }
 }
 #endif
 
 #if DEBUG
 
 static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
 {
         int i, size;
         char *realobj;
 
         if (cachep->flags & SLAB_RED_ZONE) {
                 printk(KERN_ERR "Redzone: 0x%llx/0x%llx.\n",
                         *dbg_redzone1(cachep, objp),
                         *dbg_redzone2(cachep, objp));
         }
 
         if (cachep->flags & SLAB_STORE_USER) {
                 printk(KERN_ERR "Last user: [<%p>]",
                         *dbg_userword(cachep, objp));
                 print_symbol("(%s)",
                                 (unsigned long)*dbg_userword(cachep, objp));
                 printk("\n");
         }
         realobj = (char *)objp + obj_offset(cachep);
         size = obj_size(cachep);
         for (i = 0; i < size && lines; i += 16, lines--) {
                 int limit;
                 limit = 16;
                 if (i + limit > size)
                         limit = size - i;
                 dump_line(realobj, i, limit);
         }
 }
 
 static void check_poison_obj(struct kmem_cache *cachep, void *objp)
 {
         char *realobj;
         int size, i;
         int lines = 0;
 
         realobj = (char *)objp + obj_offset(cachep);
         size = obj_size(cachep);
 
         for (i = 0; i < size; i++) {
                 char exp = POISON_FREE;
                 if (i == size - 1)
                         exp = POISON_END;
                 if (realobj[i] != exp) {
                         int limit;
                         /* Mismatch ! */
                         /* Print header */
                         if (lines == 0) {
                                 printk(KERN_ERR
                                         "Slab corruption: %s start=%p, len=%d\n",
                                         cachep->name, realobj, size);
                                 print_objinfo(cachep, objp, 0);
                         }
                         /* Hexdump the affected line */
                         i = (i / 16) * 16;
                         limit = 16;
                         if (i + limit > size)
                                 limit = size - i;
                         dump_line(realobj, i, limit);
                         i += 16;
                         lines++;
                         /* Limit to 5 lines */
                         if (lines > 5)
                                 break;
                 }
         }
         if (lines != 0) {
                 /* Print some data about the neighboring objects, if they
                  * exist:
                  */
                 struct slab *slabp = virt_to_slab(objp);
                 unsigned int objnr;
 
                 objnr = obj_to_index(cachep, slabp, objp);
                 if (objnr) {
                         objp = index_to_obj(cachep, slabp, objnr - 1);
                         realobj = (char *)objp + obj_offset(cachep);
                         printk(KERN_ERR "Prev obj: start=%p, len=%d\n",
                                realobj, size);
                         print_objinfo(cachep, objp, 2);
                 }
                 if (objnr + 1 < cachep->num) {
                         objp = index_to_obj(cachep, slabp, objnr + 1);
                         realobj = (char *)objp + obj_offset(cachep);
                         printk(KERN_ERR "Next obj: start=%p, len=%d\n",
                                realobj, size);
                         print_objinfo(cachep, objp, 2);
                 }
         }
 }
 #endif
 
 static void
 __cache_free(struct kmem_cache *cachep, void *objp, int *this_cpu);
 
 #if DEBUG
 
 /**
  * slab_destroy_objs - destroy a slab and its objects
  * @cachep: cache pointer being destroyed
  * @slabp: slab pointer being destroyed
  *
  * Call the registered destructor for each object in a slab that is being
  * destroyed.
  */
 static void
 slab_destroy_objs(struct kmem_cache *cachep, struct slab *slabp)
 {
         int i;
         for (i = 0; i < cachep->num; i++) {
                 void *objp = index_to_obj(cachep, slabp, i);
 
                 if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                         if (cachep->buffer_size % PAGE_SIZE == 0 &&
                                         OFF_SLAB(cachep))
                                 kernel_map_pages(virt_to_page(objp),
                                         cachep->buffer_size / PAGE_SIZE, 1);
                         else
                                 check_poison_obj(cachep, objp);
 #else
                         check_poison_obj(cachep, objp);
 #endif
                 }
                 if (cachep->flags & SLAB_RED_ZONE) {
                         if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
                                 slab_error(cachep, "start of a freed object "
                                            "was overwritten");
                         if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
                                 slab_error(cachep, "end of a freed object "
                                            "was overwritten");
                 }
         }
 }
 #else
 static void slab_destroy_objs(struct kmem_cache *cachep, struct slab *slabp)
 {
 }
 #endif
 
 /**
  * slab_destroy - destroy and release all objects in a slab
  * @cachep: cache pointer being destroyed
  * @slabp: slab pointer being destroyed
  *
  * Destroy all the objs in a slab, and release the mem back to the system.
  * Before calling the slab must have been unlinked from the cache.  The
  * cache-lock is not held/needed.
  */
 static void
 slab_destroy(struct kmem_cache *cachep, struct slab *slabp, int *this_cpu)
 {
         void *addr = slabp->s_mem - slabp->colouroff;
 
         slab_destroy_objs(cachep, slabp);
         if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) {
                 struct slab_rcu *slab_rcu;
 
                 slab_rcu = (struct slab_rcu *)slabp;
                 slab_rcu->cachep = cachep;
                 slab_rcu->addr = addr;
                 call_rcu(&slab_rcu->head, kmem_rcu_free);
         } else {
                 kmem_freepages(cachep, addr);
                 if (OFF_SLAB(cachep)) {
                         if (this_cpu)
                                 __cache_free(cachep->slabp_cache, slabp, this_cpu);
                         else
                                 kmem_cache_free(cachep->slabp_cache, slabp);
                 }
         }
 }
 
 static void __kmem_cache_destroy(struct kmem_cache *cachep)
 {
         int i;
         struct kmem_list3 *l3;
 
         for_each_online_cpu(i)
             kfree(cachep->array[i]);
 
         /* NUMA: free the list3 structures */
         for_each_online_node(i) {
                 l3 = cachep->nodelists[i];
                 if (l3) {
                         kfree(l3->shared);
                         free_alien_cache(l3->alien);
                         kfree(l3);
                 }
         }
         kmem_cache_free(&cache_cache, cachep);
 }
 
 
 /**
  * calculate_slab_order - calculate size (page order) of slabs
  * @cachep: pointer to the cache that is being created
  * @size: size of objects to be created in this cache.
  * @align: required alignment for the objects.
  * @flags: slab allocation flags
  *
  * Also calculates the number of objects per slab.
  *
  * This could be made much more intelligent.  For now, try to avoid using
  * high order pages for slabs.  When the gfp() functions are more friendly
  * towards high-order requests, this should be changed.
  */
 static size_t calculate_slab_order(struct kmem_cache *cachep,
                         size_t size, size_t align, unsigned long flags)
 {
         unsigned long offslab_limit;
         size_t left_over = 0;
         int gfporder;
 
         for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
                 unsigned int num;
                 size_t remainder;
 
                 cache_estimate(gfporder, size, align, flags, &remainder, &num);
                 if (!num)
                         continue;
 
                 if (flags & CFLGS_OFF_SLAB) {
                         /*
                          * Max number of objs-per-slab for caches which
                          * use off-slab slabs. Needed to avoid a possible
                          * looping condition in cache_grow().
                          */
                         offslab_limit = size - sizeof(struct slab);
                         offslab_limit /= sizeof(kmem_bufctl_t);
 
                         if (num > offslab_limit)
                                 break;
                 }
 
                 /* Found something acceptable - save it away */
                 cachep->num = num;
                 cachep->gfporder = gfporder;
                 left_over = remainder;
 
                 /*
                  * A VFS-reclaimable slab tends to have most allocations
                  * as GFP_NOFS and we really don't want to have to be allocating
                  * higher-order pages when we are unable to shrink dcache.
                  */
                 if (flags & SLAB_RECLAIM_ACCOUNT)
                         break;
 
                 /*
                  * Large number of objects is good, but very large slabs are
                  * currently bad for the gfp()s.
                  */
                 if (gfporder >= slab_break_gfp_order)
                         break;
 
                 /*
                  * Acceptable internal fragmentation?
                  */
                 if (left_over * 8 <= (PAGE_SIZE << gfporder))
                         break;
         }
         return left_over;
 }
 
 static int __init_refok setup_cpu_cache(struct kmem_cache *cachep)
 {
         int this_cpu;
 
         if (g_cpucache_up == FULL)
                 return enable_cpucache(cachep);
 
         if (g_cpucache_up == NONE) {
                 /*
                  * Note: the first kmem_cache_create must create the cache
                  * that's used by kmalloc(24), otherwise the creation of
                  * further caches will BUG().
                  */
                 cachep->array[smp_processor_id()] = &initarray_generic.cache;
 
                 /*
                  * If the cache that's used by kmalloc(sizeof(kmem_list3)) is
                  * the first cache, then we need to set up all its list3s,
                  * otherwise the creation of further caches will BUG().
                  */
                 set_up_list3s(cachep, SIZE_AC);
                 if (INDEX_AC == INDEX_L3)
                         g_cpucache_up = PARTIAL_L3;
                 else
                         g_cpucache_up = PARTIAL_AC;
         } else {
                 cachep->array[smp_processor_id()] =
                         kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
 
                 if (g_cpucache_up == PARTIAL_AC) {
                         set_up_list3s(cachep, SIZE_L3);
                         g_cpucache_up = PARTIAL_L3;
                 } else {
                         int node;
                         for_each_online_node(node) {
                                 cachep->nodelists[node] =
                                     kmalloc_node(sizeof(struct kmem_list3),
                                                 GFP_KERNEL, node);
                                 BUG_ON(!cachep->nodelists[node]);
                                 kmem_list3_init(cachep->nodelists[node]);
                         }
                 }
         }
         cachep->nodelists[numa_node_id()]->next_reap =
                         jiffies + REAPTIMEOUT_LIST3 +
                         ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
 
         this_cpu = raw_smp_processor_id();
 
         cpu_cache_get(cachep, this_cpu)->avail = 0;
         cpu_cache_get(cachep, this_cpu)->limit = BOOT_CPUCACHE_ENTRIES;
         cpu_cache_get(cachep, this_cpu)->batchcount = 1;
         cpu_cache_get(cachep, this_cpu)->touched = 0;
         cachep->batchcount = 1;
         cachep->limit = BOOT_CPUCACHE_ENTRIES;
         return 0;
 }
 
 /**
  * kmem_cache_create - Create a cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
  * @size: The size of objects to be created in this cache.
  * @align: The required alignment for the objects.
  * @flags: SLAB flags
  * @ctor: A constructor for the objects.
  *
  * Returns a ptr to the cache on success, NULL on failure.
  * Cannot be called within a int, but can be interrupted.
  * The @ctor is run when new pages are allocated by the cache.
  *
  * @name must be valid until the cache is destroyed. This implies that
  * the module calling this has to destroy the cache before getting unloaded.
  *
  * The flags are
  *
  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
  * to catch references to uninitialised memory.
  *
  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
  * for buffer overruns.
  *
  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
  * cacheline.  This can be beneficial if you're counting cycles as closely
  * as davem.
  */
 struct kmem_cache *
 kmem_cache_create (const char *name, size_t size, size_t align,
         unsigned long flags,
         void (*ctor)(struct kmem_cache *, void *))
 {
         size_t left_over, slab_size, ralign;
         struct kmem_cache *cachep = NULL, *pc;
 
         /*
          * Sanity checks... these are all serious usage bugs.
          */
         if (!name || in_interrupt() || (size < BYTES_PER_WORD) ||
             size > KMALLOC_MAX_SIZE) {
                 printk(KERN_ERR "%s: Early error in slab %s\n", __FUNCTION__,
                                 name);
                 BUG();
         }
 
         /*
          * We use cache_chain_mutex to ensure a consistent view of
          * cpu_online_map as well.  Please see cpuup_callback
          */
         get_online_cpus();
         mutex_lock(&cache_chain_mutex);
 
         list_for_each_entry(pc, &cache_chain, next) {
                 char tmp;
                 int res;
 
                 /*
                  * This happens when the module gets unloaded and doesn't
                  * destroy its slab cache and no-one else reuses the vmalloc
                  * area of the module.  Print a warning.
                  */
                 res = probe_kernel_address(pc->name, tmp);
                 if (res) {
                         printk(KERN_ERR
                                "SLAB: cache with size %d has lost its name\n",
                                pc->buffer_size);
                         continue;
                 }
 
                 if (!strcmp(pc->name, name)) {
                         printk(KERN_ERR
                                "kmem_cache_create: duplicate cache %s\n", name);
                         dump_stack();
                         goto oops;
                 }
         }
 
 #if DEBUG
         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
 #if FORCED_DEBUG
         /*
          * Enable redzoning and last user accounting, except for caches with
          * large objects, if the increased size would increase the object size
          * above the next power of two: caches with object sizes just above a
          * power of two have a significant amount of internal fragmentation.
          */
         if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
                                                 2 * sizeof(unsigned long long)))
                 flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
         if (!(flags & SLAB_DESTROY_BY_RCU))
                 flags |= SLAB_POISON;
 #endif
         if (flags & SLAB_DESTROY_BY_RCU)
                 BUG_ON(flags & SLAB_POISON);
 #endif
         /*
          * Always checks flags, a caller might be expecting debug support which
          * isn't available.
          */
         BUG_ON(flags & ~CREATE_MASK);
 
         /*
          * Check that size is in terms of words.  This is needed to avoid
          * unaligned accesses for some archs when redzoning is used, and makes
          * sure any on-slab bufctl's are also correctly aligned.
          */
         if (size & (BYTES_PER_WORD - 1)) {
                 size += (BYTES_PER_WORD - 1);
                 size &= ~(BYTES_PER_WORD - 1);
         }
 
         /* calculate the final buffer alignment: */
 
         /* 1) arch recommendation: can be overridden for debug */
         if (flags & SLAB_HWCACHE_ALIGN) {
                 /*
                  * Default alignment: as specified by the arch code.  Except if
                  * an object is really small, then squeeze multiple objects into
                  * one cacheline.
                  */
                 ralign = cache_line_size();
                 while (size <= ralign / 2)
                         ralign /= 2;
         } else {
                 ralign = BYTES_PER_WORD;
         }
 
         /*
          * Redzoning and user store require word alignment or possibly larger.
          * Note this will be overridden by architecture or caller mandated
          * alignment if either is greater than BYTES_PER_WORD.
          */
         if (flags & SLAB_STORE_USER)
                 ralign = BYTES_PER_WORD;
 
         if (flags & SLAB_RED_ZONE) {
                 ralign = REDZONE_ALIGN;
                 /* If redzoning, ensure that the second redzone is suitably
                  * aligned, by adjusting the object size accordingly. */
                 size += REDZONE_ALIGN - 1;
                 size &= ~(REDZONE_ALIGN - 1);
         }
 
         /* 2) arch mandated alignment */
         if (ralign < ARCH_SLAB_MINALIGN) {
                 ralign = ARCH_SLAB_MINALIGN;
         }
         /* 3) caller mandated alignment */
         if (ralign < align) {
                 ralign = align;
         }
         /* disable debug if necessary */
         if (ralign > __alignof__(unsigned long long))
                 flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
         /*
          * 4) Store it.
          */
         align = ralign;
 
         /* Get cache's description obj. */
         cachep = kmem_cache_zalloc(&cache_cache, GFP_KERNEL);
         if (!cachep)
                 goto oops;
 
 #if DEBUG
         cachep->obj_size = size;
 
         /*
          * Both debugging options require word-alignment which is calculated
          * into align above.
          */
         if (flags & SLAB_RED_ZONE) {
                 /* add space for red zone words */
                 cachep->obj_offset += sizeof(unsigned long long);
                 size += 2 * sizeof(unsigned long long);
         }
         if (flags & SLAB_STORE_USER) {
                 /* user store requires one word storage behind the end of
                  * the real object. But if the second red zone needs to be
                  * aligned to 64 bits, we must allow that much space.
                  */
                 if (flags & SLAB_RED_ZONE)
                         size += REDZONE_ALIGN;
                 else
                         size += BYTES_PER_WORD;
         }
 #if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)
         if (size >= malloc_sizes[INDEX_L3 + 1].cs_size
             && cachep->obj_size > cache_line_size() && size < PAGE_SIZE) {
                 cachep->obj_offset += PAGE_SIZE - size;
                 size = PAGE_SIZE;
         }
 #endif
 #endif
 
         /*
          * Determine if the slab management is 'on' or 'off' slab.
          * (bootstrapping cannot cope with offslab caches so don't do
          * it too early on.)
          */
         if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init)
                 /*
                  * Size is large, assume best to place the slab management obj
                  * off-slab (should allow better packing of objs).
                  */
                 flags |= CFLGS_OFF_SLAB;
 
         size = ALIGN(size, align);
 
         left_over = calculate_slab_order(cachep, size, align, flags);
 
         if (!cachep->num) {
                 printk(KERN_ERR
                        "kmem_cache_create: couldn't create cache %s.\n", name);
                 kmem_cache_free(&cache_cache, cachep);
                 cachep = NULL;
                 goto oops;
         }
         slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
                           + sizeof(struct slab), align);
 
         /*
          * If the slab has been placed off-slab, and we have enough space then
          * move it on-slab. This is at the expense of any extra colouring.
          */
         if (flags & CFLGS_OFF_SLAB && left_over >= slab_size) {
                 flags &= ~CFLGS_OFF_SLAB;
                 left_over -= slab_size;
         }
 
         if (flags & CFLGS_OFF_SLAB) {
                 /* really off slab. No need for manual alignment */
                 slab_size =
                     cachep->num * sizeof(kmem_bufctl_t) + sizeof(struct slab);
         }
 
         cachep->colour_off = cache_line_size();
         /* Offset must be a multiple of the alignment. */
         if (cachep->colour_off < align)
                 cachep->colour_off = align;
         cachep->colour = left_over / cachep->colour_off;
         cachep->slab_size = slab_size;
         cachep->flags = flags;
         cachep->gfpflags = 0;
         if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA))
                 cachep->gfpflags |= GFP_DMA;
         cachep->buffer_size = size;
         cachep->reciprocal_buffer_size = reciprocal_value(size);
 
         if (flags & CFLGS_OFF_SLAB) {
                 cachep->slabp_cache = kmem_find_general_cachep(slab_size, 0u);
                 /*
                  * This is a possibility for one of the malloc_sizes caches.
                  * But since we go off slab only for object size greater than
                  * PAGE_SIZE/8, and malloc_sizes gets created in ascending order,
                  * this should not happen at all.
                  * But leave a BUG_ON for some lucky dude.
                  */
                 BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));
         }
         cachep->ctor = ctor;
         cachep->name = name;
 
         if (setup_cpu_cache(cachep)) {
                 __kmem_cache_destroy(cachep);
                 cachep = NULL;
                 goto oops;
         }
 
         /* cache setup completed, link it into the list */
         list_add(&cachep->next, &cache_chain);
 oops:
         if (!cachep && (flags & SLAB_PANIC))
                 panic("kmem_cache_create(): failed to create slab `%s'\n",
                       name);
         mutex_unlock(&cache_chain_mutex);
         put_online_cpus();
         return cachep;
 }
 EXPORT_SYMBOL(kmem_cache_create);
 
 #if DEBUG
 static void check_irq_off(void)
 {
 /*
  * On PREEMPT_RT we use locks to protect the per-CPU lists,
  * and keep interrupts enabled.
  */
 #ifndef CONFIG_PREEMPT_RT
         BUG_ON(!irqs_disabled());
 #endif
 }
 
 static void check_irq_on(void)
 {
 #ifndef CONFIG_PREEMPT_RT
         BUG_ON(irqs_disabled());
 #endif
 }
 
 static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
 {
 #ifdef CONFIG_SMP
         check_irq_off();
         assert_spin_locked(&cachep->nodelists[node]->list_lock);
 #endif
 }
 
 #else
 #define check_irq_off() do { } while(0)
 #define check_irq_on()  do { } while(0)
 #define check_spinlock_acquired_node(x, y) do { } while(0)
 #endif
 
 static int drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
                         struct array_cache *ac,
                         int force, int node);
 
 static void __do_drain(void *arg, int this_cpu)
 {
         struct kmem_cache *cachep = arg;
         int node = cpu_to_node(this_cpu);
         struct array_cache *ac;
 
         check_irq_off();
         ac = cpu_cache_get(cachep, this_cpu);
         spin_lock(&cachep->nodelists[node]->list_lock);
         free_block(cachep, ac->entry, ac->avail, node, &this_cpu);
         spin_unlock(&cachep->nodelists[node]->list_lock);
         ac->avail = 0;
 }
 
 #ifdef CONFIG_PREEMPT_RT
 static void do_drain(void *arg, int this_cpu)
 {
         __do_drain(arg, this_cpu);
 }
 #else
 static void do_drain(void *arg)
 {
         __do_drain(arg, smp_processor_id());
 }
 #endif
 
 #ifdef CONFIG_PREEMPT_RT
 /*
  * execute func() for all CPUs. On PREEMPT_RT we dont actually have
  * to run on the remote CPUs - we only have to take their CPU-locks.
  * (This is a rare operation, so cacheline bouncing is not an issue.)
  */
 static void
 slab_on_each_cpu(void (*func)(void *arg, int this_cpu), void *arg)
 {
         unsigned int i;
 
         check_irq_on();
         for_each_online_cpu(i) {
                 spin_lock(&__get_cpu_lock(slab_irq_locks, i));
                 func(arg, i);
                 spin_unlock(&__get_cpu_lock(slab_irq_locks, i));
         }
 }
 #else
 # define slab_on_each_cpu(func, cachep) on_each_cpu(func, cachep, 1, 1)
 #endif
 
 static void drain_cpu_caches(struct kmem_cache *cachep)
 {
         struct kmem_list3 *l3;
         int node;
 
         slab_on_each_cpu(do_drain, cachep);
         check_irq_on();
         for_each_online_node(node) {
                 l3 = cachep->nodelists[node];
                 if (l3 && l3->alien)
                         drain_alien_cache(cachep, l3->alien);
         }
 
         for_each_online_node(node) {
                 l3 = cachep->nodelists[node];
                 if (l3)
                         drain_array(cachep, l3, l3->shared, 1, node);
         }
 }
 
 /*
  * Remove slabs from the list of free slabs.
  * Specify the number of slabs to drain in tofree.
  *
  * Returns the actual number of slabs released.
  */
 static int drain_freelist(struct kmem_cache *cache,
                         struct kmem_list3 *l3, int tofree)
 {
         struct list_head *p;
         int nr_freed, this_cpu;
         struct slab *slabp;
 
         nr_freed = 0;
         while (nr_freed < tofree && !list_empty(&l3->slabs_free)) {
 
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
                 p = l3->slabs_free.prev;
                 if (p == &l3->slabs_free) {
                         slab_spin_unlock_irq(&l3->list_lock, this_cpu);
                         goto out;
                 }
 
                 slabp = list_entry(p, struct slab, list);
 #if DEBUG
                 BUG_ON(slabp->inuse);
 #endif
                 list_del(&slabp->list);
                 l3->free_objects -= cache->num;
                 slab_destroy(cache, slabp, &this_cpu);
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
                 nr_freed++;
         }
 out:
         return nr_freed;
 }
 
 /* Called with cache_chain_mutex held to protect against cpu hotplug */
 static int __cache_shrink(struct kmem_cache *cachep)
 {
         int ret = 0, i = 0;
         struct kmem_list3 *l3;
 
         drain_cpu_caches(cachep);
 
         check_irq_on();
         for_each_online_node(i) {
                 l3 = cachep->nodelists[i];
                 if (!l3)
                         continue;
 
                 drain_freelist(cachep, l3, l3->free_objects);
 
                 ret += !list_empty(&l3->slabs_full) ||
                         !list_empty(&l3->slabs_partial);
         }
         return (ret ? 1 : 0);
 }
 
 /**
  * kmem_cache_shrink - Shrink a cache.
  * @cachep: The cache to shrink.
  *
  * Releases as many slabs as possible for a cache.
  * To help debugging, a zero exit status indicates all slabs were released.
  */
 int kmem_cache_shrink(struct kmem_cache *cachep)
 {
         int ret;
         BUG_ON(!cachep || in_interrupt());
 
         get_online_cpus();
         mutex_lock(&cache_chain_mutex);
         ret = __cache_shrink(cachep);
         mutex_unlock(&cache_chain_mutex);
         put_online_cpus();
         return ret;
 }
 EXPORT_SYMBOL(kmem_cache_shrink);
 
 /**
  * kmem_cache_destroy - delete a cache
  * @cachep: the cache to destroy
  *
  * Remove a &struct kmem_cache object from the slab cache.
  *
  * It is expected this function will be called by a module when it is
  * unloaded.  This will remove the cache completely, and avoid a duplicate
  * cache being allocated each time a module is loaded and unloaded, if the
  * module doesn't have persistent in-kernel storage across loads and unloads.
  *
  * The cache must be empty before calling this function.
  *
  * The caller must guarantee that noone will allocate memory from the cache
  * during the kmem_cache_destroy().
  */
 void kmem_cache_destroy(struct kmem_cache *cachep)
 {
         BUG_ON(!cachep || in_interrupt());
 
         /* Find the cache in the chain of caches. */
         get_online_cpus();
         mutex_lock(&cache_chain_mutex);
         /*
          * the chain is never empty, cache_cache is never destroyed
          */
         list_del(&cachep->next);
         if (__cache_shrink(cachep)) {
                 slab_error(cachep, "Can't free all objects");
                 list_add(&cachep->next, &cache_chain);
                 mutex_unlock(&cache_chain_mutex);
                 put_online_cpus();
                 return;
         }
 
         if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
                 synchronize_rcu();
 
         __kmem_cache_destroy(cachep);
         mutex_unlock(&cache_chain_mutex);
         put_online_cpus();
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
 
 /*
  * Get the memory for a slab management obj.
  * For a slab cache when the slab descriptor is off-slab, slab descriptors
  * always come from malloc_sizes caches.  The slab descriptor cannot
  * come from the same cache which is getting created because,
  * when we are searching for an appropriate cache for these
  * descriptors in kmem_cache_create, we search through the malloc_sizes array.
  * If we are creating a malloc_sizes cache here it would not be visible to
  * kmem_find_general_cachep till the initialization is complete.
  * Hence we cannot have slabp_cache same as the original cache.
  */
 static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
                                    int colour_off, gfp_t local_flags,
                                    int nodeid)
 {
         struct slab *slabp;
 
         if (OFF_SLAB(cachep)) {
                 /* Slab management obj is off-slab. */
                 slabp = kmem_cache_alloc_node(cachep->slabp_cache,
                                               local_flags & ~GFP_THISNODE, nodeid);
                 if (!slabp)
                         return NULL;
         } else {
                 slabp = objp + colour_off;
                 colour_off += cachep->slab_size;
         }
         slabp->inuse = 0;
         slabp->colouroff = colour_off;
         slabp->s_mem = objp + colour_off;
         slabp->nodeid = nodeid;
         slabp->free = 0;
         return slabp;
 }
 
 static inline kmem_bufctl_t *slab_bufctl(struct slab *slabp)
 {
         return (kmem_bufctl_t *) (slabp + 1);
 }
 
 static void cache_init_objs(struct kmem_cache *cachep,
                             struct slab *slabp)
 {
         int i;
 
         for (i = 0; i < cachep->num; i++) {
                 void *objp = index_to_obj(cachep, slabp, i);
 #if DEBUG
                 /* need to poison the objs? */
                 if (cachep->flags & SLAB_POISON)
                         poison_obj(cachep, objp, POISON_FREE);
                 if (cachep->flags & SLAB_STORE_USER)
                         *dbg_userword(cachep, objp) = NULL;
 
                 if (cachep->flags & SLAB_RED_ZONE) {
                         *dbg_redzone1(cachep, objp) = RED_INACTIVE;
                         *dbg_redzone2(cachep, objp) = RED_INACTIVE;
                 }
                 /*
                  * Constructors are not allowed to allocate memory from the same
                  * cache which they are a constructor for.  Otherwise, deadlock.
                  * They must also be threaded.
                  */
                 if (cachep->ctor && !(cachep->flags & SLAB_POISON))
                         cachep->ctor(cachep, objp + obj_offset(cachep));
 
                 if (cachep->flags & SLAB_RED_ZONE) {
                         if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
                                 slab_error(cachep, "constructor overwrote the"
                                            " end of an object");
                         if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
                                 slab_error(cachep, "constructor overwrote the"
                                            " start of an object");
                 }
                 if ((cachep->buffer_size % PAGE_SIZE) == 0 &&
                             OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
                         kernel_map_pages(virt_to_page(objp),
                                          cachep->buffer_size / PAGE_SIZE, 0);
 #else
                 if (cachep->ctor)
                         cachep->ctor(cachep, objp);
 #endif
                 slab_bufctl(slabp)[i] = i + 1;
         }
         slab_bufctl(slabp)[i - 1] = BUFCTL_END;
 }
 
 static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
 {
         if (CONFIG_ZONE_DMA_FLAG) {
                 if (flags & GFP_DMA)
                         BUG_ON(!(cachep->gfpflags & GFP_DMA));
                 else
                         BUG_ON(cachep->gfpflags & GFP_DMA);
         }
 }
 
 static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slabp,
                                 int nodeid)
 {
         void *objp = index_to_obj(cachep, slabp, slabp->free);
         kmem_bufctl_t next;
 
         slabp->inuse++;
         next = slab_bufctl(slabp)[slabp->free];
 #if DEBUG
         slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE;
         WARN_ON(slabp->nodeid != nodeid);
 #endif
         slabp->free = next;
 
         return objp;
 }
 
 static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
                                 void *objp, int nodeid)
 {
         unsigned int objnr = obj_to_index(cachep, slabp, objp);
 
 #if DEBUG
         /* Verify that the slab belongs to the intended node */
         WARN_ON(slabp->nodeid != nodeid);
 
         if (slab_bufctl(slabp)[objnr] + 1 <= SLAB_LIMIT + 1) {
                 printk(KERN_ERR "slab: double free detected in cache "
                                 "'%s', objp %p\n", cachep->name, objp);
                 BUG();
         }
 #endif
         slab_bufctl(slabp)[objnr] = slabp->free;
         slabp->free = objnr;
         slabp->inuse--;
 }
 
 /*
  * Map pages beginning at addr to the given cache and slab. This is required
  * for the slab allocator to be able to lookup the cache and slab of a
  * virtual address for kfree, ksize, kmem_ptr_validate, and slab debugging.
  */
 static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
                            void *addr)
 {
         int nr_pages;
         struct page *page;
 
         page = virt_to_page(addr);
 
         nr_pages = 1;
         if (likely(!PageCompound(page)))
                 nr_pages <<= cache->gfporder;
 
         do {
                 page_set_cache(page, cache);
                 page_set_slab(page, slab);
                 page++;
         } while (--nr_pages);
 }
 
 /*
  * Grow (by 1) the number of slabs within a cache.  This is called by
  * kmem_cache_alloc() when there are no active objs left in a cache.
  */
 static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid,
                       void *objp, int *this_cpu)
 {
         struct slab *slabp;
         size_t offset;
         gfp_t local_flags;
         struct kmem_list3 *l3;
 
         /*
          * Be lazy and only check for valid flags here,  keeping it out of the
          * critical path in kmem_cache_alloc().
          */
         BUG_ON(flags & GFP_SLAB_BUG_MASK);
         local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
         /* Take the l3 list lock to change the colour_next on this node */
         check_irq_off();
         l3 = cachep->nodelists[nodeid];
         spin_lock(&l3->list_lock);
 
         /* Get colour for the slab, and cal the next value. */
         offset = l3->colour_next;
         l3->colour_next++;
         if (l3->colour_next >= cachep->colour)
                 l3->colour_next = 0;
         spin_unlock(&l3->list_lock);
 
         offset *= cachep->colour_off;
 
         if (local_flags & __GFP_WAIT)
                 slab_irq_enable_nort(*this_cpu);
         slab_irq_enable_rt(*this_cpu);
 
         /*
          * The test for missing atomic flag is performed here, rather than
          * the more obvious place, simply to reduce the critical path length
          * in kmem_cache_alloc(). If a caller is seriously mis-behaving they
          * will eventually be caught here (where it matters).
          */
         kmem_flagcheck(cachep, flags);
 
         /*
          * Get mem for the objs.  Attempt to allocate a physical page from
          * 'nodeid'.
          */
         if (!objp)
                 objp = kmem_getpages(cachep, local_flags, nodeid);
         if (!objp)
                 goto failed;
 
         /* Get slab management. */
         slabp = alloc_slabmgmt(cachep, objp, offset,
                         local_flags & ~GFP_CONSTRAINT_MASK, nodeid);
         if (!slabp)
                 goto opps1;
 
         slab_map_pages(cachep, slabp, objp);
 
         cache_init_objs(cachep, slabp);
 
         slab_irq_disable_rt(*this_cpu);
         if (local_flags & __GFP_WAIT)
                 slab_irq_disable_nort(*this_cpu);
 
         check_irq_off();
         spin_lock(&l3->list_lock);
 
         /* Make slab active. */
         list_add_tail(&slabp->list, &(l3->slabs_free));
         STATS_INC_GROWN(cachep);
         l3->free_objects += cachep->num;
         spin_unlock(&l3->list_lock);
         return 1;
 opps1:
         kmem_freepages(cachep, objp);
 failed:
         slab_irq_disable_rt(*this_cpu);
         if (local_flags & __GFP_WAIT)
                 slab_irq_disable_nort(*this_cpu);
         return 0;
 }
 
 #if DEBUG
 
 /*
  * Perform extra freeing checks:
  * - detect bad pointers.
  * - POISON/RED_ZONE checking
  */
 static void kfree_debugcheck(const void *objp)
 {
         if (!virt_addr_valid(objp)) {
                 printk(KERN_ERR "kfree_debugcheck: out of range ptr %lxh.\n",
                        (unsigned long)objp);
                 BUG();
         }
 }
 
 static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
 {
         unsigned long long redzone1, redzone2;
 
         redzone1 = *dbg_redzone1(cache, obj);
         redzone2 = *dbg_redzone2(cache, obj);
 
         /*
          * Redzone is ok.
          */
         if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
                 return;
 
         if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
                 slab_error(cache, "double free detected");
         else
                 slab_error(cache, "memory outside object was overwritten");
 
         printk(KERN_ERR "%p: redzone 1:0x%llx, redzone 2:0x%llx.\n",
                         obj, redzone1, redzone2);
 }
 
 static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
                                    void *caller)
 {
         struct page *page;
         unsigned int objnr;
         struct slab *slabp;
 
         BUG_ON(virt_to_cache(objp) != cachep);
 
         objp -= obj_offset(cachep);
         kfree_debugcheck(objp);
         page = virt_to_head_page(objp);
 
         slabp = page_get_slab(page);
 
         if (cachep->flags & SLAB_RED_ZONE) {
                 verify_redzone_free(cachep, objp);
                 *dbg_redzone1(cachep, objp) = RED_INACTIVE;
                 *dbg_redzone2(cachep, objp) = RED_INACTIVE;
         }
         if (cachep->flags & SLAB_STORE_USER)
                 *dbg_userword(cachep, objp) = caller;
 
         objnr = obj_to_index(cachep, slabp, objp);
 
         BUG_ON(objnr >= cachep->num);
         BUG_ON(objp != index_to_obj(cachep, slabp, objnr));
 
 #ifdef CONFIG_DEBUG_SLAB_LEAK
         slab_bufctl(slabp)[objnr] = BUFCTL_FREE;
 #endif
         if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                 if ((cachep->buffer_size % PAGE_SIZE)==0 && OFF_SLAB(cachep)) {
                         store_stackinfo(cachep, objp, (unsigned long)caller);
                         kernel_map_pages(virt_to_page(objp),
                                          cachep->buffer_size / PAGE_SIZE, 0);
                 } else {
                         poison_obj(cachep, objp, POISON_FREE);
                 }
 #else
                 poison_obj(cachep, objp, POISON_FREE);
 #endif
         }
         return objp;
 }
 
 static void check_slabp(struct kmem_cache *cachep, struct slab *slabp)
 {
         kmem_bufctl_t i;
         int entries = 0;
 
         /* Check slab's freelist to see if this obj is there. */
         for (i = slabp->free; i != BUFCTL_END; i = slab_bufctl(slabp)[i]) {
                 entries++;
                 if (entries > cachep->num || i >= cachep->num)
                         goto bad;
         }
         if (entries != cachep->num - slabp->inuse) {
 bad:
                 printk(KERN_ERR "slab: Internal list corruption detected in "
                                 "cache '%s'(%d), slabp %p(%d). Hexdump:\n",
                         cachep->name, cachep->num, slabp, slabp->inuse);
                 for (i = 0;
                      i < sizeof(*slabp) + cachep->num * sizeof(kmem_bufctl_t);
                      i++) {
                         if (i % 16 == 0)
                                 printk("\n%03x:", i);
                         printk(" %02x", ((unsigned char *)slabp)[i]);
                 }
                 printk("\n");
                 BUG();
         }
 }
 #else
 #define kfree_debugcheck(x) do { } while(0)
 #define cache_free_debugcheck(x,objp,z) (objp)
 #define check_slabp(x,y) do { } while(0)
 #endif
 
 static void *
 cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags, int *this_cpu)
 {
         int batchcount;
         struct kmem_list3 *l3;
         struct array_cache *ac;
         int node;
 
 retry:
         check_irq_off();
         node = numa_node_id();
         ac = cpu_cache_get(cachep, *this_cpu);
         batchcount = ac->batchcount;
         if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
                 /*
                  * If there was little recent activity on this cache, then
                  * perform only a partial refill.  Otherwise we could generate
                  * refill bouncing.
                  */
                 batchcount = BATCHREFILL_LIMIT;
         }
         l3 = cachep->nodelists[cpu_to_node(*this_cpu)];
 
         BUG_ON(ac->avail > 0 || !l3);
         spin_lock(&l3->list_lock);
 
         /* See if we can refill from the shared array */
         if (l3->shared && transfer_objects(ac, l3->shared, batchcount))
                 goto alloc_done;
 
         while (batchcount > 0) {
                 struct list_head *entry;
                 struct slab *slabp;
                 /* Get slab alloc is to come from. */
                 entry = l3->slabs_partial.next;
                 if (entry == &l3->slabs_partial) {
                         l3->free_touched = 1;
                         entry = l3->slabs_free.next;
                         if (entry == &l3->slabs_free)
                                 goto must_grow;
                 }
 
                 slabp = list_entry(entry, struct slab, list);
                 check_slabp(cachep, slabp);
                 check_spinlock_acquired_node(cachep, cpu_to_node(*this_cpu));
 
                 /*
                  * The slab was either on partial or free list so
                  * there must be at least one object available for
                  * allocation.
                  */
                 BUG_ON(slabp->inuse < 0 || slabp->inuse >= cachep->num);
 
                 while (slabp->inuse < cachep->num && batchcount--) {
                         STATS_INC_ALLOCED(cachep);
                         STATS_INC_ACTIVE(cachep);
                         STATS_SET_HIGH(cachep);
 
                         ac->entry[ac->avail++] =
                                 slab_get_obj(cachep, slabp,
                                              cpu_to_node(*this_cpu));
                 }
                 check_slabp(cachep, slabp);
 
                 /* move slabp to correct slabp list: */
                 list_del(&slabp->list);
                 if (slabp->free == BUFCTL_END)
                         list_add(&slabp->list, &l3->slabs_full);
                 else
                         list_add(&slabp->list, &l3->slabs_partial);
         }
 
 must_grow:
         l3->free_objects -= ac->avail;
 alloc_done:
         spin_unlock(&l3->list_lock);
 
         if (unlikely(!ac->avail)) {
                 int x;
                 x = cache_grow(cachep, flags | GFP_THISNODE, cpu_to_node(*this_cpu), NULL, this_cpu);
 
                 /* cache_grow can reenable interrupts, then ac could change. */
                 ac = cpu_cache_get(cachep, *this_cpu);
                 if (!x && ac->avail == 0)       /* no objects in sight? abort */
                         return NULL;
 
                 if (!ac->avail)         /* objects refilled by interrupt? */
                         goto retry;
         }
         ac->touched = 1;
         return ac->entry[--ac->avail];
 }
 
 static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
                                                 gfp_t flags)
 {
         might_sleep_if(flags & __GFP_WAIT);
 #if DEBUG
         kmem_flagcheck(cachep, flags);
 #endif
 }
 
 #if DEBUG
 static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
                                 gfp_t flags, void *objp, void *caller)
 {
         if (!objp)
                 return objp;
         if (cachep->flags & SLAB_POISON) {
 #ifdef CONFIG_DEBUG_PAGEALLOC
                 if ((cachep->buffer_size % PAGE_SIZE) == 0 && OFF_SLAB(cachep))
                         kernel_map_pages(virt_to_page(objp),
                                          cachep->buffer_size / PAGE_SIZE, 1);
                 else
                         check_poison_obj(cachep, objp);
 #else
                 check_poison_obj(cachep, objp);
 #endif
                 poison_obj(cachep, objp, POISON_INUSE);
         }
         if (cachep->flags & SLAB_STORE_USER)
                 *dbg_userword(cachep, objp) = caller;
 
         if (cachep->flags & SLAB_RED_ZONE) {
                 if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
                                 *dbg_redzone2(cachep, objp) != RED_INACTIVE) {
                         slab_error(cachep, "double free, or memory outside"
                                                 " object was overwritten");
                         printk(KERN_ERR
                                 "%p: redzone 1:0x%llx, redzone 2:0x%llx\n",
                                 objp, *dbg_redzone1(cachep, objp),
                                 *dbg_redzone2(cachep, objp));
                 }
                 *dbg_redzone1(cachep, objp) = RED_ACTIVE;
                 *dbg_redzone2(cachep, objp) = RED_ACTIVE;
         }
 #ifdef CONFIG_DEBUG_SLAB_LEAK
         {
                 struct slab *slabp;
                 unsigned objnr;
 
                 slabp = page_get_slab(virt_to_head_page(objp));
                 objnr = (unsigned)(objp - slabp->s_mem) / cachep->buffer_size;
                 slab_bufctl(slabp)[objnr] = BUFCTL_ACTIVE;
         }
 #endif
         objp += obj_offset(cachep);
         if (cachep->ctor && cachep->flags & SLAB_POISON)
                 cachep->ctor(cachep, objp);
 #if ARCH_SLAB_MINALIGN
         if ((u32)objp & (ARCH_SLAB_MINALIGN-1)) {
                 printk(KERN_ERR "0x%p: not aligned to ARCH_SLAB_MINALIGN=%d\n",
                        objp, ARCH_SLAB_MINALIGN);
         }
 #endif
         return objp;
 }
 #else
 #define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
 #endif
 
 #ifdef CONFIG_FAILSLAB
 
 static struct failslab_attr {
 
         struct fault_attr attr;
 
         u32 ignore_gfp_wait;
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
         struct dentry *ignore_gfp_wait_file;
 #endif
 
 } failslab = {
         .attr = FAULT_ATTR_INITIALIZER,
         .ignore_gfp_wait = 1,
 };
 
 static int __init setup_failslab(char *str)
 {
         return setup_fault_attr(&failslab.attr, str);
 }
 __setup("failslab=", setup_failslab);
 
 static int should_failslab(struct kmem_cache *cachep, gfp_t flags)
 {
         if (cachep == &cache_cache)
                 return 0;
         if (flags & __GFP_NOFAIL)
                 return 0;
         if (failslab.ignore_gfp_wait && (flags & __GFP_WAIT))
                 return 0;
 
         return should_fail(&failslab.attr, obj_size(cachep));
 }
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 
 static int __init failslab_debugfs(void)
 {
         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
         struct dentry *dir;
         int err;
 
         err = init_fault_attr_dentries(&failslab.attr, "failslab");
         if (err)
                 return err;
         dir = failslab.attr.dentries.dir;
 
         failslab.ignore_gfp_wait_file =
                 debugfs_create_bool("ignore-gfp-wait", mode, dir,
                                       &failslab.ignore_gfp_wait);
 
         if (!failslab.ignore_gfp_wait_file) {
                 err = -ENOMEM;
                 debugfs_remove(failslab.ignore_gfp_wait_file);
                 cleanup_fault_attr_dentries(&failslab.attr);
         }
 
         return err;
 }
 
 late_initcall(failslab_debugfs);
 
 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
 
 #else /* CONFIG_FAILSLAB */
 
 static inline int should_failslab(struct kmem_cache *cachep, gfp_t flags)
 {
         return 0;
 }
 
 #endif /* CONFIG_FAILSLAB */
 
 static inline void *
 ____cache_alloc(struct kmem_cache *cachep, gfp_t flags, int *this_cpu)
 {
         void *objp;
         struct array_cache *ac;
 
         check_irq_off();
 
         ac = cpu_cache_get(cachep, *this_cpu);
         if (likely(ac->avail)) {
                 STATS_INC_ALLOCHIT(cachep);
                 ac->touched = 1;
                 objp = ac->entry[--ac->avail];
         } else {
                 STATS_INC_ALLOCMISS(cachep);
                 objp = cache_alloc_refill(cachep, flags, this_cpu);
         }
         return objp;
 }
 
 #ifdef CONFIG_NUMA
 /*
  * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.
  *
  * If we are in_interrupt, then process context, including cpusets and
  * mempolicy, may not apply and should not be used for allocation policy.
  */
 static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags,
                                 int *this_cpu)
 {
         int nid_alloc, nid_here;
 
         if (in_interrupt() || (flags & __GFP_THISNODE))
                 return NULL;
         nid_alloc = nid_here = numa_node_id();
         if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
                 nid_alloc = cpuset_mem_spread_node();
         else if (current->mempolicy)
                 nid_alloc = slab_node(current->mempolicy);
         if (nid_alloc != nid_here)
                 return ____cache_alloc_node(cachep, flags, nid_alloc, this_cpu);
         return NULL;
 }
 
 /*
  * Fallback function if there was no memory available and no objects on a
  * certain node and fall back is permitted. First we scan all the
  * available nodelists for available objects. If that fails then we
  * perform an allocation without specifying a node. This allows the page
  * allocator to do its reclaim / fallback magic. We then insert the
  * slab into the proper nodelist and then allocate from it.
  */
 static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags, int *this_cpu)
 {
         struct zonelist *zonelist;
         gfp_t local_flags;
         struct zone **z;
         void *obj = NULL;
         int nid;
 
         if (flags & __GFP_THISNODE)
                 return NULL;
 
         zonelist = &NODE_DATA(slab_node(current->mempolicy))
                         ->node_zonelists[gfp_zone(flags)];
         local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
 retry:
         /*
          * Look through allowed nodes for objects available
          * from existing per node queues.
          */
         for (z = zonelist->zones; *z && !obj; z++) {
                 nid = zone_to_nid(*z);
 
                 if (cpuset_zone_allowed_hardwall(*z, flags) &&
                         cache->nodelists[nid] &&
                         cache->nodelists[nid]->free_objects)
 
                         obj = ____cache_alloc_node(cache,
                                                    flags | GFP_THISNODE, nid,
                                                    this_cpu);
         }
 
         if (!obj) {
                 /*
                  * This allocation will be performed within the constraints
                  * of the current cpuset / memory policy requirements.
                  * We may trigger various forms of reclaim on the allowed
                  * set and go into memory reserves if necessary.
                  */
                 if (local_flags & __GFP_WAIT)
                         slab_irq_enable_nort(*this_cpu);
                 slab_irq_enable_rt(*this_cpu);
 
                 kmem_flagcheck(cache, flags);
                 obj = kmem_getpages(cache, local_flags, -1);
 
                 slab_irq_disable_rt(*this_cpu);
                 if (local_flags & __GFP_WAIT)
                         slab_irq_disable_nort(*this_cpu);
 
                 if (obj) {
                         /*
                          * Insert into the appropriate per node queues
                          */
                         nid = page_to_nid(virt_to_page(obj));
                         if (cache_grow(cache, flags, nid, obj, this_cpu)) {
                                 obj = ____cache_alloc_node(cache,
                                         flags | GFP_THISNODE, nid, this_cpu);
                                 if (!obj)
                                         /*
                                          * Another processor may allocate the
                                          * objects in the slab since we are
                                          * not holding any locks.
                                          */
                                         goto retry;
                         } else {
                                 /* cache_grow already freed obj */
                                 obj = NULL;
                         }
                 }
         }
         return obj;
 }
 
 /*
  * A interface to enable slab creation on nodeid
  */
 static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
                                 int nodeid, int *this_cpu)
 {
         struct list_head *entry;
         struct slab *slabp;
         struct kmem_list3 *l3;
         void *obj;
         int x;
 
         l3 = cachep->nodelists[nodeid];
         BUG_ON(!l3);
 
 retry:
         check_irq_off();
         spin_lock(&l3->list_lock);
         entry = l3->slabs_partial.next;
         if (entry == &l3->slabs_partial) {
                 l3->free_touched = 1;
                 entry = l3->slabs_free.next;
                 if (entry == &l3->slabs_free)
                         goto must_grow;
         }
 
         slabp = list_entry(entry, struct slab, list);
         check_spinlock_acquired_node(cachep, nodeid);
         check_slabp(cachep, slabp);
 
         STATS_INC_NODEALLOCS(cachep);
         STATS_INC_ACTIVE(cachep);
         STATS_SET_HIGH(cachep);
 
         BUG_ON(slabp->inuse == cachep->num);
 
         obj = slab_get_obj(cachep, slabp, nodeid);
         check_slabp(cachep, slabp);
         l3->free_objects--;
         /* move slabp to correct slabp list: */
         list_del(&slabp->list);
 
         if (slabp->free == BUFCTL_END)
                 list_add(&slabp->list, &l3->slabs_full);
         else
                 list_add(&slabp->list, &l3->slabs_partial);
 
         spin_unlock(&l3->list_lock);
         goto done;
 
 must_grow:
         spin_unlock(&l3->list_lock);
         x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL, this_cpu);
         if (x)
                 goto retry;
 
         return fallback_alloc(cachep, flags, this_cpu);
 
 done:
         return obj;
 }
 
 /**
  * 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.
  * @caller: return address of caller, used for debug information
  *
  * Identical to kmem_cache_alloc but it will allocate memory on the given
  * node, which can improve the performance for cpu bound structures.
  *
  * Fallback to other node is possible if __GFP_THISNODE is not set.
  */
 static __always_inline void *
 __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
                    void *caller)
 {
         unsigned long irqflags;
         int this_cpu;
         void *ptr;
 
         if (should_failslab(cachep, flags))
                 return NULL;
 
         cache_alloc_debugcheck_before(cachep, flags);
 
         slab_irq_save(irqflags, this_cpu);
 
         if (unlikely(nodeid == -1))
                 nodeid = cpu_to_node(this_cpu);
 
         if (unlikely(!cachep->nodelists[nodeid])) {
                 /* Node not bootstrapped yet */
                 ptr = fallback_alloc(cachep, flags, &this_cpu);
                 goto out;
         }
 
         if (nodeid == cpu_to_node(this_cpu)) {
                 /*
                  * Use the locally cached objects if possible.
                  * However ____cache_alloc does not allow fallback
                  * to other nodes. It may fail while we still have
                  * objects on other nodes available.
                  */
                 ptr = ____cache_alloc(cachep, flags, &this_cpu);
                 if (ptr)
                         goto out;
         }
         /* ___cache_alloc_node can fall back to other nodes */
         ptr = ____cache_alloc_node(cachep, flags, nodeid, &this_cpu);
   out:
         slab_irq_restore(irqflags, this_cpu);
         ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
 
         if (unlikely((flags & __GFP_ZERO) && ptr))
                 memset(ptr, 0, obj_size(cachep));
 
         return ptr;
 }
 
 static __always_inline void *
 __do_cache_alloc(struct kmem_cache *cache, gfp_t flags, int *this_cpu)
 {
         void *objp;
 
         if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
                 objp = alternate_node_alloc(cache, flags, this_cpu);
                 if (objp)
                         goto out;
         }
 
         objp = ____cache_alloc(cache, flags, this_cpu);
         /*
          * We may just have run out of memory on the local node.
          * ____cache_alloc_node() knows how to locate memory on other nodes
          */
         if (!objp)
                 objp = ____cache_alloc_node(cache, flags,
                                             cpu_to_node(*this_cpu), this_cpu);
   out:
         return objp;
 }
 #else
 
 static __always_inline void *
 __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int *this_cpu)
 {
         return ____cache_alloc(cachep, flags, this_cpu);
 }
 
 #endif /* CONFIG_NUMA */
 
 static __always_inline void *
 __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
 {
         unsigned long save_flags;
         int this_cpu;
         void *objp;
 
         if (should_failslab(cachep, flags))
                 return NULL;
 
         cache_alloc_debugcheck_before(cachep, flags);
         slab_irq_save(save_flags, this_cpu);
         objp = __do_cache_alloc(cachep, flags, &this_cpu);
         slab_irq_restore(save_flags, this_cpu);
         objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
         prefetchw(objp);
 
         if (unlikely((flags & __GFP_ZERO) && objp))
                 memset(objp, 0, obj_size(cachep));
 
         return objp;
 }
 
 /*
  * Caller needs to acquire correct kmem_list's list_lock
  */
 static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
                        int node, int *this_cpu)
 {
         int i;
         struct kmem_list3 *l3;
 
         for (i = 0; i < nr_objects; i++) {
                 void *objp = objpp[i];
                 struct slab *slabp;
 
                 slabp = virt_to_slab(objp);
                 l3 = cachep->nodelists[node];
                 list_del(&slabp->list);
                 check_spinlock_acquired_node(cachep, node);
                 check_slabp(cachep, slabp);
                 slab_put_obj(cachep, slabp, objp, node);
                 STATS_DEC_ACTIVE(cachep);
                 l3->free_objects++;
                 check_slabp(cachep, slabp);
 
                 /* fixup slab chains */
                 if (slabp->inuse == 0) {
                         if (l3->free_objects > l3->free_limit) {
                                 l3->free_objects -= cachep->num;
                                 /* No need to drop any previously held
                                  * lock here, even if we have a off-slab slab
                                  * descriptor it is guaranteed to come from
                                  * a different cache, refer to comments before
                                  * alloc_slabmgmt.
                                  */
                                 slab_destroy(cachep, slabp, this_cpu);
                         } else {
                                 list_add(&slabp->list, &l3->slabs_free);
                         }
                 } else {
                         /* Unconditionally move a slab to the end of the
                          * partial list on free - maximum time for the
                          * other objects to be freed, too.
                          */
                         list_add_tail(&slabp->list, &l3->slabs_partial);
                 }
         }
 }
 
 static void
 cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac, int *this_cpu)
 {
         int batchcount;
         struct kmem_list3 *l3;
         int node = cpu_to_node(*this_cpu);
 
         batchcount = ac->batchcount;
 #if DEBUG
         BUG_ON(!batchcount || batchcount > ac->avail);
 #endif
         check_irq_off();
         l3 = cachep->nodelists[node];
         spin_lock(&l3->list_lock);
         if (l3->shared) {
                 struct array_cache *shared_array = l3->shared;
                 int max = shared_array->limit - shared_array->avail;
                 if (max) {
                         if (batchcount > max)
                                 batchcount = max;
                         memcpy(&(shared_array->entry[shared_array->avail]),
                                ac->entry, sizeof(void *) * batchcount);
                         shared_array->avail += batchcount;
                         goto free_done;
                 }
         }
 
         free_block(cachep, ac->entry, batchcount, node, this_cpu);
 free_done:
 #if STATS
         {
                 int i = 0;
                 struct list_head *p;
 
                 p = l3->slabs_free.next;
                 while (p != &(l3->slabs_free)) {
                         struct slab *slabp;
 
                         slabp = list_entry(p, struct slab, list);
                         BUG_ON(slabp->inuse);
 
                         i++;
                         p = p->next;
                 }
                 STATS_SET_FREEABLE(cachep, i);
         }
 #endif
         spin_unlock(&l3->list_lock);
         ac->avail -= batchcount;
         memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
 }
 
 /*
  * Release an obj back to its cache. If the obj has a constructed state, it must
  * be in this state _before_ it is released.  Called with disabled ints.
  */
 static void __cache_free(struct kmem_cache *cachep, void *objp, int *this_cpu)
 {
         struct array_cache *ac = cpu_cache_get(cachep, *this_cpu);
 
         check_irq_off();
         objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));
 
         /*
          * Skip calling cache_free_alien() when the platform is not numa.
          * This will avoid cache misses that happen while accessing slabp (which
          * is per page memory  reference) to get nodeid. Instead use a global
          * variable to skip the call, which is mostly likely to be present in
          * the cache.
          */
         if (numa_platform && cache_free_alien(cachep, objp, this_cpu))
                 return;
 
         if (likely(ac->avail < ac->limit)) {
                 STATS_INC_FREEHIT(cachep);
                 ac->entry[ac->avail++] = objp;
                 return;
         } else {
                 STATS_INC_FREEMISS(cachep);
                 cache_flusharray(cachep, ac, this_cpu);
                 ac->entry[ac->avail++] = objp;
         }
 }
 
 /**
  * kmem_cache_alloc - Allocate an object
  * @cachep: The cache to allocate from.
  * @flags: See kmalloc().
  *
  * Allocate an object from this cache.  The flags are only relevant
  * if the cache has no available objects.
  */
 void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
         return __cache_alloc(cachep, flags, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(kmem_cache_alloc);
 
 /**
  * kmem_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 kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr)
 {
         unsigned long addr = (unsigned long)ptr;
         unsigned long min_addr = PAGE_OFFSET;
         unsigned long align_mask = BYTES_PER_WORD - 1;
         unsigned long size = cachep->buffer_size;
         struct page *page;
 
         if (unlikely(addr < min_addr))
                 goto out;
         if (unlikely(addr > (unsigned long)high_memory - size))
                 goto out;
         if (unlikely(addr & align_mask))
                 goto out;
         if (unlikely(!kern_addr_valid(addr)))
                 goto out;
         if (unlikely(!kern_addr_valid(addr + size - 1)))
                 goto out;
         page = virt_to_page(ptr);
         if (unlikely(!PageSlab(page)))
                 goto out;
         if (unlikely(page_get_cache(page) != cachep))
                 goto out;
         return 1;
 out:
         return 0;
 }
 
 #ifdef CONFIG_NUMA
 void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
         return __cache_alloc_node(cachep, flags, nodeid,
                         __builtin_return_address(0));
 }
 EXPORT_SYMBOL(kmem_cache_alloc_node);
 
 static __always_inline void *
 __do_kmalloc_node(size_t size, gfp_t flags, int node, void *caller)
 {
         struct kmem_cache *cachep;
 
         cachep = kmem_find_general_cachep(size, flags);
         if (unlikely(ZERO_OR_NULL_PTR(cachep)))
                 return cachep;
         return kmem_cache_alloc_node(cachep, flags, node);
 }
 
 #ifdef CONFIG_DEBUG_SLAB
 void *__kmalloc_node(size_t size, gfp_t flags, int node)
 {
         return __do_kmalloc_node(size, flags, node,
                         __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__kmalloc_node);
 
 void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
                 int node, void *caller)
 {
         return __do_kmalloc_node(size, flags, node, caller);
 }
 EXPORT_SYMBOL(__kmalloc_node_track_caller);
 #else
 void *__kmalloc_node(size_t size, gfp_t flags, int node)
 {
         return __do_kmalloc_node(size, flags, node, NULL);
 }
 EXPORT_SYMBOL(__kmalloc_node);
 #endif /* CONFIG_DEBUG_SLAB */
 #endif /* CONFIG_NUMA */
 
 /**
  * __do_kmalloc - allocate memory
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kmalloc).
  * @caller: function caller for debug tracking of the caller
  */
 static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
                                           void *caller)
 {
         struct kmem_cache *cachep;
 
         /* If you want to save a few bytes .text space: replace
          * __ with kmem_.
          * Then kmalloc uses the uninlined functions instead of the inline
          * functions.
          */
         cachep = __find_general_cachep(size, flags);
         if (unlikely(ZERO_OR_NULL_PTR(cachep)))
                 return cachep;
         return __cache_alloc(cachep, flags, caller);
 }
 
 
 #ifdef CONFIG_DEBUG_SLAB
 void *__kmalloc(size_t size, gfp_t flags)
 {
         return __do_kmalloc(size, flags, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__kmalloc);
 
 void *__kmalloc_track_caller(size_t size, gfp_t flags, void *caller)
 {
         return __do_kmalloc(size, flags, caller);
 }
 EXPORT_SYMBOL(__kmalloc_track_caller);
 
 #else
 void *__kmalloc(size_t size, gfp_t flags)
 {
         return __do_kmalloc(size, flags, NULL);
 }
 EXPORT_SYMBOL(__kmalloc);
 #endif
 
 /**
  * kmem_cache_free - Deallocate an object
  * @cachep: The cache the allocation was from.
  * @objp: The previously allocated object.
  *
  * Free an object which was previously allocated from this
  * cache.
  */
 void kmem_cache_free(struct kmem_cache *cachep, void *objp)
 {
         unsigned long flags;
         int this_cpu;
 
         slab_irq_save(flags, this_cpu);
         debug_check_no_locks_freed(objp, obj_size(cachep));
         __cache_free(cachep, objp, &this_cpu);
         slab_irq_restore(flags, this_cpu);
 }
 EXPORT_SYMBOL(kmem_cache_free);
 
 /**
  * kfree - free previously allocated memory
  * @objp: pointer returned by kmalloc.
  *
  * If @objp is NULL, no operation is performed.
  *
  * Don't free memory not originally allocated by kmalloc()
  * or you will run into trouble.
  */
 void kfree(const void *objp)
 {
         struct kmem_cache *c;
         unsigned long flags;
         int this_cpu;
 
         if (unlikely(ZERO_OR_NULL_PTR(objp)))
                 return;
         slab_irq_save(flags, this_cpu);
         kfree_debugcheck(objp);
         c = virt_to_cache(objp);
         debug_check_no_locks_freed(objp, obj_size(c));
         __cache_free(c, (void *)objp, &this_cpu);
         slab_irq_restore(flags, this_cpu);
 }
 EXPORT_SYMBOL(kfree);
 
 unsigned int kmem_cache_size(struct kmem_cache *cachep)
 {
         return obj_size(cachep);
 }
 EXPORT_SYMBOL(kmem_cache_size);
 
 const char *kmem_cache_name(struct kmem_cache *cachep)
 {
         return cachep->name;
 }
 EXPORT_SYMBOL_GPL(kmem_cache_name);
 
 /*
  * This initializes kmem_list3 or resizes various caches for all nodes.
  */
 static int alloc_kmemlist(struct kmem_cache *cachep)
 {
         int node, this_cpu;
         struct kmem_list3 *l3;
         struct array_cache *new_shared;
         struct array_cache **new_alien = NULL;
 
         for_each_online_node(node) {
 
                 if (use_alien_caches) {
                         new_alien = alloc_alien_cache(node, cachep->limit);
                         if (!new_alien)
                                 goto fail;
                 }
 
                 new_shared = NULL;
                 if (cachep->shared) {
                         new_shared = alloc_arraycache(node,
                                 cachep->shared*cachep->batchcount,
                                         0xbaadf00d);
                         if (!new_shared) {
                                 free_alien_cache(new_alien);
                                 goto fail;
                         }
                 }
 
                 l3 = cachep->nodelists[node];
                 if (l3) {
                         struct array_cache *shared = l3->shared;
 
                         slab_spin_lock_irq(&l3->list_lock, this_cpu);
 
                         if (shared)
                                 free_block(cachep, shared->entry,
                                            shared->avail, node, &this_cpu);
 
                         l3->shared = new_shared;
                         if (!l3->alien) {
                                 l3->alien = new_alien;
                                 new_alien = NULL;
                         }
                         l3->free_limit = (1 + nr_cpus_node(node)) *
                                         cachep->batchcount + cachep->num;
                         slab_spin_unlock_irq(&l3->list_lock, this_cpu);
                         kfree(shared);
                         free_alien_cache(new_alien);
                         continue;
                 }
                 l3 = kmalloc_node(sizeof(struct kmem_list3), GFP_KERNEL, node);
                 if (!l3) {
                         free_alien_cache(new_alien);
                         kfree(new_shared);
                         goto fail;
                 }
 
                 kmem_list3_init(l3);
                 l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
                                 ((unsigned long)cachep) % REAPTIMEOUT_LIST3;
                 l3->shared = new_shared;
                 l3->alien = new_alien;
                 l3->free_limit = (1 + nr_cpus_node(node)) *
                                         cachep->batchcount + cachep->num;
                 cachep->nodelists[node] = l3;
         }
         return 0;
 
 fail:
         if (!cachep->next.next) {
                 /* Cache is not active yet. Roll back what we did */
                 node--;
                 while (node >= 0) {
                         if (cachep->nodelists[node]) {
                                 l3 = cachep->nodelists[node];
 
                                 kfree(l3->shared);
                                 free_alien_cache(l3->alien);
                                 kfree(l3);
                                 cachep->nodelists[node] = NULL;
                         }
                         node--;
                 }
         }
         return -ENOMEM;
 }
 
 struct ccupdate_struct {
         struct kmem_cache *cachep;
         struct array_cache *new[NR_CPUS];
 };
 
 static void __do_ccupdate_local(void *info, int this_cpu)
 {
         struct ccupdate_struct *new = info;
         struct array_cache *old;
 
         check_irq_off();
         old = cpu_cache_get(new->cachep, this_cpu);
 
         new->cachep->array[this_cpu] = new->new[this_cpu];
         new->new[this_cpu] = old;
 }
 
 #ifdef CONFIG_PREEMPT_RT
 static void do_ccupdate_local(void *arg, int this_cpu)
 {
         __do_ccupdate_local(arg, this_cpu);
 }
 #else
 static void do_ccupdate_local(void *arg)
 {
         __do_ccupdate_local(arg, smp_processor_id());
 }
 #endif
 
 /* Always called with the cache_chain_mutex held */
 static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
                                 int batchcount, int shared)
 {
         struct ccupdate_struct new;
         int i, this_cpu;
 
         memset(&new.new, 0, sizeof(new.new));
         for_each_online_cpu(i) {
                 new.new[i] = alloc_arraycache(cpu_to_node(i), limit,
                                                 batchcount);
                 if (!new.new[i]) {
                         for (i--; i >= 0; i--)
                                 kfree(new.new[i]);
                         return -ENOMEM;
                 }
         }
         new.cachep = cachep;
 
         slab_on_each_cpu(do_ccupdate_local, (void *)&new);
 
         check_irq_on();
         cachep->batchcount = batchcount;
         cachep->limit = limit;
         cachep->shared = shared;
 
         for_each_online_cpu(i) {
                 struct array_cache *ccold = new.new[i];
                 if (!ccold)
                         continue;
                 slab_spin_lock_irq(&cachep->nodelists[cpu_to_node(i)]->list_lock, this_cpu);
                 free_block(cachep, ccold->entry, ccold->avail, cpu_to_node(i), &this_cpu);
                 slab_spin_unlock_irq(&cachep->nodelists[cpu_to_node(i)]->list_lock, this_cpu);
                 kfree(ccold);
         }
 
         return alloc_kmemlist(cachep);
 }
 
 /* Called with cache_chain_mutex held always */
 static int enable_cpucache(struct kmem_cache *cachep)
 {
         int err;
         int limit, shared;
 
         /*
          * The head array serves three purposes:
          * - create a LIFO ordering, i.e. return objects that are cache-warm
          * - reduce the number of spinlock operations.
          * - reduce the number of linked list operations on the slab and
          *   bufctl chains: array operations are cheaper.
          * The numbers are guessed, we should auto-tune as described by
          * Bonwick.
          */
         if (cachep->buffer_size > 131072)
                 limit = 1;
         else if (cachep->buffer_size > PAGE_SIZE)
                 limit = 8;
         else if (cachep->buffer_size > 1024)
                 limit = 24;
         else if (cachep->buffer_size > 256)
                 limit = 54;
         else
                 limit = 120;
 
         /*
          * CPU bound tasks (e.g. network routing) can exhibit cpu bound
          * allocation behaviour: Most allocs on one cpu, most free operations
          * on another cpu. For these cases, an efficient object passing between
          * cpus is necessary. This is provided by a shared array. The array
          * replaces Bonwick's magazine layer.
          * On uniprocessor, it's functionally equivalent (but less efficient)
          * to a larger limit. Thus disabled by default.
          */
         shared = 0;
         if (cachep->buffer_size <= PAGE_SIZE && num_possible_cpus() > 1)
                 shared = 8;
 
 #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);
         return err;
 }
 
 /*
  * Drain an array if it contains any elements taking the l3 lock only if
  * necessary. Note that the l3 listlock also protects the array_cache
  * if drain_array() is used on the shared array.
  * returns non-zero if some work is done
  */
 int drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
                  struct array_cache *ac, int force, int node)
 {
         int tofree, this_cpu;
 
         if (!ac || !ac->avail)
                 return 0;
         if (ac->touched && !force) {
                 ac->touched = 0;
         } else {
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
                 if (ac->avail) {
                         tofree = force ? ac->avail : (ac->limit + 4) / 5;
                         if (tofree > ac->avail)
                                 tofree = (ac->avail + 1) / 2;
                         free_block(cachep, ac->entry, tofree, node, &this_cpu);
                         ac->avail -= tofree;
                         memmove(ac->entry, &(ac->entry[tofree]),
                                 sizeof(void *) * ac->avail);
                 }
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
         }
         return 1;
 }
 
 /**
  * cache_reap - Reclaim memory from caches.
  * @w: work descriptor
  *
  * Called from workqueue/eventd every few seconds.
  * Purpose:
  * - clear the per-cpu caches for this CPU.
  * - return freeable pages to the main free memory pool.
  *
  * If we cannot acquire the cache chain mutex then just give up - we'll try
  * again on the next iteration.
  */
 static void cache_reap(struct work_struct *w)
 {
         int this_cpu = raw_smp_processor_id(), node = cpu_to_node(this_cpu);
         struct kmem_cache *searchp;
         struct kmem_list3 *l3;
         struct delayed_work *work =
                 container_of(w, struct delayed_work, work);
         int work_done = 0;
 
         if (!mutex_trylock(&cache_chain_mutex))
                 /* Give up. Setup the next iteration. */
                 goto out;
 
         list_for_each_entry(searchp, &cache_chain, next) {
                 check_irq_on();
 
                 /*
                  * We only take the l3 lock if absolutely necessary and we
                  * have established with reasonable certainty that
                  * we can do some work if the lock was obtained.
                  */
                 l3 = searchp->nodelists[node];
 
                 work_done += reap_alien(searchp, l3, &this_cpu);
 
                 node = cpu_to_node(this_cpu);
 
                 work_done += drain_array(searchp, l3,
                             cpu_cache_get(searchp, this_cpu), 0, node);
 
                 /*
                  * These are racy checks but it does not matter
                  * if we skip one check or scan twice.
                  */
                 if (time_after(l3->next_reap, jiffies))
                         goto next;
 
                 l3->next_reap = jiffies + REAPTIMEOUT_LIST3;
 
                 work_done += drain_array(searchp, l3, l3->shared, 0, node);
 
                 if (l3->free_touched)
                         l3->free_touched = 0;
                 else {
                         int freed;
 
                         freed = drain_freelist(searchp, l3, (l3->free_limit +
                                 5 * searchp->num - 1) / (5 * searchp->num));
                         STATS_ADD_REAPED(searchp, freed);
                 }
 next:
                 cond_resched();
         }
         check_irq_on();
         mutex_unlock(&cache_chain_mutex);
         next_reap_node();
 out:
         /* Set up the next iteration */
         schedule_delayed_work(work,
                 round_jiffies_relative((1+!work_done) * REAPTIMEOUT_CPUC));
 }
 
 #ifdef CONFIG_SLABINFO
 
 static void print_slabinfo_header(struct seq_file *m)
 {
         /*
          * Output format version, so at least we can change it
          * without _too_ many complaints.
          */
 #if STATS
         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
 #else
         seq_puts(m, "slabinfo - version: 2.1\n");
 #endif
         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
                  "<objperslab> <pagesperslab>");
         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
 #if STATS
         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
 #endif
         seq_putc(m, '\n');
 }
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
         loff_t n = *pos;
 
         mutex_lock(&cache_chain_mutex);
         if (!n)
                 print_slabinfo_header(m);
 
         return seq_list_start(&cache_chain, *pos);
 }
 
 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 {
         return seq_list_next(p, &cache_chain, pos);
 }
 
 static void s_stop(struct seq_file *m, void *p)
 {
         mutex_unlock(&cache_chain_mutex);
 }
 
 static int s_show(struct seq_file *m, void *p)
 {
         struct kmem_cache *cachep = list_entry(p, struct kmem_cache, next);
         struct slab *slabp;
         unsigned long active_objs;
         unsigned long num_objs;
         unsigned long active_slabs = 0;
         unsigned long num_slabs, free_objects = 0, shared_avail = 0;
         const char *name;
         char *error = NULL;
         int this_cpu, node;
         struct kmem_list3 *l3;
 
         active_objs = 0;
         num_slabs = 0;
         for_each_online_node(node) {
                 l3 = cachep->nodelists[node];
                 if (!l3)
                         continue;
 
                 check_irq_on();
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
 
                 list_for_each_entry(slabp, &l3->slabs_full, list) {
                         if (slabp->inuse != cachep->num && !error)
                                 error = "slabs_full accounting error";
                         active_objs += cachep->num;
                         active_slabs++;
                 }
                 list_for_each_entry(slabp, &l3->slabs_partial, list) {
                         if (slabp->inuse == cachep->num && !error)
                                 error = "slabs_partial inuse accounting error";
                         if (!slabp->inuse && !error)
                                 error = "slabs_partial/inuse accounting error";
                         active_objs += slabp->inuse;
                         active_slabs++;
                 }
                 list_for_each_entry(slabp, &l3->slabs_free, list) {
                         if (slabp->inuse && !error)
                                 error = "slabs_free/inuse accounting error";
                         num_slabs++;
                 }
                 free_objects += l3->free_objects;
                 if (l3->shared)
                         shared_avail += l3->shared->avail;
 
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
         }
         num_slabs += active_slabs;
         num_objs = num_slabs * cachep->num;
         if (num_objs - active_objs != free_objects && !error)
                 error = "free_objects accounting error";
 
         name = cachep->name;
         if (error)
                 printk(KERN_ERR "slab: cache %s error: %s\n", name, error);
 
         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
                    name, active_objs, num_objs, cachep->buffer_size,
                    cachep->num, (1 << cachep->gfporder));
         seq_printf(m, " : tunables %4u %4u %4u",
                    cachep->limit, cachep->batchcount, cachep->shared);
         seq_printf(m, " : slabdata %6lu %6lu %6lu",
                    active_slabs, num_slabs, shared_avail);
 #if STATS
         {                       /* list3 stats */
                 unsigned long high = cachep->high_mark;
                 unsigned long allocs = cachep->num_allocations;
                 unsigned long grown = cachep->grown;
                 unsigned long reaped = cachep->reaped;
                 unsigned long errors = cachep->errors;
                 unsigned long max_freeable = cachep->max_freeable;
                 unsigned long node_allocs = cachep->node_allocs;
                 unsigned long node_frees = cachep->node_frees;
                 unsigned long overflows = cachep->node_overflow;
 
                 seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu \
                                 %4lu %4lu %4lu %4lu %4lu", allocs, high, grown,
                                 reaped, errors, max_freeable, node_allocs,
                                 node_frees, overflows);
         }
         /* cpu stats */
         {
                 unsigned long allochit = atomic_read(&cachep->allochit);
                 unsigned long allocmiss = atomic_read(&cachep->allocmiss);
                 unsigned long freehit = atomic_read(&cachep->freehit);
                 unsigned long freemiss = atomic_read(&cachep->freemiss);
 
                 seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
                            allochit, allocmiss, freehit, freemiss);
         }
 #endif
         seq_putc(m, '\n');
         return 0;
 }
 
 /*
  * slabinfo_op - iterator that generates /proc/slabinfo
  *
  * Output layout:
  * cache-name
  * num-active-objs
  * total-objs
  * object size
  * num-active-slabs
  * total-slabs
  * num-pages-per-slab
  * + further values on SMP and with statistics enabled
  */
 
 const struct seq_operations slabinfo_op = {
         .start = s_start,
         .next = s_next,
         .stop = s_stop,
         .show = s_show,
 };
 
 #define MAX_SLABINFO_WRITE 128
 /**
  * slabinfo_write - Tuning for the slab allocator
  * @file: unused
  * @buffer: user buffer
  * @count: data length
  * @ppos: unused
  */
 ssize_t slabinfo_write(struct file *file, const char __user * buffer,
                        size_t count, loff_t *ppos)
 {
         char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
         int limit, batchcount, shared, res;
         struct kmem_cache *cachep;
 
         if (count > MAX_SLABINFO_WRITE)
                 return -EINVAL;
         if (copy_from_user(&kbuf, buffer, count))
                 return -EFAULT;
         kbuf[MAX_SLABINFO_WRITE] = '\0';
 
         tmp = strchr(kbuf, ' ');
         if (!tmp)
                 return -EINVAL;
         *tmp = '\0';
         tmp++;
         if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
                 return -EINVAL;
 
         /* Find the cache in the chain of caches. */
         mutex_lock(&cache_chain_mutex);
         res = -EINVAL;
         list_for_each_entry(cachep, &cache_chain, next) {
                 if (!strcmp(cachep->name, kbuf)) {
                         if (limit < 1 || batchcount < 1 ||
                                         batchcount > limit || shared < 0) {
                                 res = 0;
                         } else {
                                 res = do_tune_cpucache(cachep, limit,
                                                        batchcount, shared);
                         }
                         break;
                 }
         }
         mutex_unlock(&cache_chain_mutex);
         if (res >= 0)
                 res = count;
         return res;
 }
 
 #ifdef CONFIG_DEBUG_SLAB_LEAK
 
 static void *leaks_start(struct seq_file *m, loff_t *pos)
 {
         mutex_lock(&cache_chain_mutex);
         return seq_list_start(&cache_chain, *pos);
 }
 
 static inline int add_caller(unsigned long *n, unsigned long v)
 {
         unsigned long *p;
         int l;
         if (!v)
                 return 1;
         l = n[1];
         p = n + 2;
         while (l) {
                 int i = l/2;
                 unsigned long *q = p + 2 * i;
                 if (*q == v) {
                         q[1]++;
                         return 1;
                 }
                 if (*q > v) {
                         l = i;
                 } else {
                         p = q + 2;
                         l -= i + 1;
                 }
         }
         if (++n[1] == n[0])
                 return 0;
         memmove(p + 2, p, n[1] * 2 * sizeof(unsigned long) - ((void *)p - (void *)n));
         p[0] = v;
         p[1] = 1;
         return 1;
 }
 
 static void handle_slab(unsigned long *n, struct kmem_cache *c, struct slab *s)
 {
         void *p;
         int i;
         if (n[0] == n[1])
                 return;
         for (i = 0, p = s->s_mem; i < c->num; i++, p += c->buffer_size) {
                 if (slab_bufctl(s)[i] != BUFCTL_ACTIVE)
                         continue;
                 if (!add_caller(n, (unsigned long)*dbg_userword(c, p)))
                         return;
         }
 }
 
 static void show_symbol(struct seq_file *m, unsigned long address)
 {
 #ifdef CONFIG_KALLSYMS
         unsigned long offset, size;
         char modname[MODULE_NAME_LEN], name[KSYM_NAME_LEN];
 
         if (lookup_symbol_attrs(address, &size, &offset, modname, name) == 0) {
                 seq_printf(m, "%s+%#lx/%#lx", name, offset, size);
                 if (modname[0])
                         seq_printf(m, " [%s]", modname);
                 return;
         }
 #endif
         seq_printf(m, "%p", (void *)address);
 }
 
 static int leaks_show(struct seq_file *m, void *p)
 {
         struct kmem_cache *cachep = list_entry(p, struct kmem_cache, next);
         struct slab *slabp;
         struct kmem_list3 *l3;
         const char *name;
         unsigned long *n = m->private;
         int node, this_cpu;
         int i;
 
         if (!(cachep->flags & SLAB_STORE_USER))
                 return 0;
         if (!(cachep->flags & SLAB_RED_ZONE))
                 return 0;
 
         /* OK, we can do it */
 
         n[1] = 0;
 
         for_each_online_node(node) {
                 l3 = cachep->nodelists[node];
                 if (!l3)
                         continue;
 
                 check_irq_on();
                 slab_spin_lock_irq(&l3->list_lock, this_cpu);
 
                 list_for_each_entry(slabp, &l3->slabs_full, list)
                         handle_slab(n, cachep, slabp);
                 list_for_each_entry(slabp, &l3->slabs_partial, list)
                         handle_slab(n, cachep, slabp);
                 slab_spin_unlock_irq(&l3->list_lock, this_cpu);
         }
         name = cachep->name;
         if (n[0] == n[1]) {
                 /* Increase the buffer size */
                 mutex_unlock(&cache_chain_mutex);
                 m->private = kzalloc(n[0] * 4 * sizeof(unsigned long), GFP_KERNEL);
                 if (!m->private) {
                         /* Too bad, we are really out */
                         m->private = n;
                         mutex_lock(&cache_chain_mutex);
                         return -ENOMEM;
                 }
                 *(unsigned long *)m->private = n[0] * 2;
                 kfree(n);
                 mutex_lock(&cache_chain_mutex);
                 /* Now make sure this entry will be retried */
                 m->count = m->size;
                 return 0;
         }
         for (i = 0; i < n[1]; i++) {
                 seq_printf(m, "%s: %lu ", name, n[2*i+3]);
                 show_symbol(m, n[2*i+2]);
                 seq_putc(m, '\n');
         }
 
         return 0;
 }
 
 const struct seq_operations slabstats_op = {
         .start = leaks_start,
         .next = s_next,
         .stop = s_stop,
         .show = leaks_show,
 };
 #endif
 #endif
 
 /**
  * ksize - get the actual amount of memory allocated for a given object
  * @objp: Pointer to the object
  *
  * kmalloc may internally round up allocations and return more memory
  * than requested. ksize() can be used to determine the actual amount of
  * memory allocated. The caller may use this additional memory, even though
  * a smaller amount of memory was initially specified with the kmalloc call.
  * The caller must guarantee that objp points to a valid object previously
  * allocated with either kmalloc() or kmem_cache_alloc(). The object
  * must not be freed during the duration of the call.
  */
 size_t ksize(const void *objp)
 {
         BUG_ON(!objp);
         if (unlikely(objp == ZERO_SIZE_PTR))
                 return 0;
 
         return obj_size(virt_to_cache(objp));
 }
 EXPORT_SYMBOL(ksize);