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 // SPDX-License-Identifier: GPL-2.0
 /*
  * 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 'slab_mutex'.
  *  The sem is only needed when accessing/extending the cache-chain, which
  *  can never happen inside an interrupt (kmem_cache_create(),
  *  kmem_cache_shrink() and kmem_cache_reap()).
  *
  *  At present, each engine can be growing a cache.  This should be blocked.
  *
  * 15 March 2005. NUMA slab allocator.
  *  Shai Fultheim <shai@scalex86.org>.
  *  Shobhit Dayal <shobhit@calsoftinc.com>
  *  Alok N Kataria <alokk@calsoftinc.com>
  *  Christoph Lameter <christoph@lameter.com>
  *
  *  Modified the slab allocator to be node aware on NUMA systems.
  *  Each node has its own list of partial, free and full slabs.
  *  All object allocations for a node occur from node specific slab lists.
  */
 
 #include    <linux/slab.h>
 #include    <linux/mm.h>
 #include    <linux/poison.h>
 #include    <linux/swap.h>
 #include    <linux/cache.h>
 #include    <linux/interrupt.h>
 #include    <linux/init.h>
 #include    <linux/compiler.h>
 #include    <linux/cpuset.h>
 #include    <linux/proc_fs.h>
 #include    <linux/seq_file.h>
 #include    <linux/notifier.h>
 #include    <linux/kallsyms.h>
 #include    <linux/kfence.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/kmemleak.h>
 #include    <linux/mempolicy.h>
 #include    <linux/mutex.h>
 #include    <linux/fault-inject.h>
 #include    <linux/rtmutex.h>
 #include    <linux/reciprocal_div.h>
 #include    <linux/debugobjects.h>
 #include    <linux/memory.h>
 #include    <linux/prefetch.h>
 #include    <linux/sched/task_stack.h>
 
 #include    <net/sock.h>
 
 #include    <asm/cacheflush.h>
 #include    <asm/tlbflush.h>
 #include    <asm/page.h>
 
 #include <trace/events/kmem.h>
 
 #include    "internal.h"
 
 #include    "slab.h"
 
 /*
  * DEBUG    - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
  *        0 for faster, smaller code (especially in the critical paths).
  *
  * STATS    - 1 to collect stats for /proc/slabinfo.
  *        0 for faster, smaller code (especially in the critical paths).
  *
  * FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
  */
 
 #ifdef CONFIG_DEBUG_SLAB
 #define DEBUG       1
 #define STATS       1
 #define FORCED_DEBUG    1
 #else
 #define DEBUG       0
 #define STATS       0
 #define FORCED_DEBUG    0
 #endif
 
 /* Shouldn't this be in a header file somewhere? */
 #define BYTES_PER_WORD      sizeof(void *)
 #define REDZONE_ALIGN       max(BYTES_PER_WORD, __alignof__(unsigned long long))
 
 #ifndef ARCH_KMALLOC_FLAGS
 #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
 #endif
 
 #define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
                 <= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
 
 #if FREELIST_BYTE_INDEX
 typedef unsigned char freelist_idx_t;
 #else
 typedef unsigned short freelist_idx_t;
 #endif
 
 #define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
 
 /*
  * 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;
     void *entry[];  /*
              * Must have this definition in here for the proper
              * alignment of array_cache. Also simplifies accessing
              * the entries.
              */
 };
 
 struct alien_cache {
     spinlock_t lock;
     struct array_cache ac;
 };
 
 /*
  * Need this for bootstrapping a per node allocator.
  */
 #define NUM_INIT_LISTS (2 * MAX_NUMNODES)
 static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
 #define CACHE_CACHE 0
 #define SIZE_NODE (MAX_NUMNODES)
 
 static int drain_freelist(struct kmem_cache *cache,
             struct kmem_cache_node *n, int tofree);
 static void free_block(struct kmem_cache *cachep, void **objpp, int len,
             int node, struct list_head *list);
 static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
 static void cache_reap(struct work_struct *unused);
 
 static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
                         void **list);
 static inline void fixup_slab_list(struct kmem_cache *cachep,
                 struct kmem_cache_node *n, struct slab *slab,
                 void **list);
 static int slab_early_init = 1;
 
 #define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
 
 static void kmem_cache_node_init(struct kmem_cache_node *parent)
 {
     INIT_LIST_HEAD(&parent->slabs_full);
     INIT_LIST_HEAD(&parent->slabs_partial);
     INIT_LIST_HEAD(&parent->slabs_free);
     parent->total_slabs = 0;
     parent->free_slabs = 0;
     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(&get_node(cachep, 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)
 
 #define CFLGS_OBJFREELIST_SLAB  ((slab_flags_t __force)0x40000000U)
 #define CFLGS_OFF_SLAB      ((slab_flags_t __force)0x80000000U)
 #define OBJFREELIST_SLAB(x) ((x)->flags & CFLGS_OBJFREELIST_SLAB)
 #define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB)
 
 #define BATCHREFILL_LIMIT   16
 /*
  * Optimization question: fewer reaps means less probability for unnecessary
  * cpucache drain/refill cycles.
  *
  * OTOH the cpuarrays can contain lots of objects,
  * which could lock up otherwise freeable slabs.
  */
 #define REAPTIMEOUT_AC      (2*HZ)
 #define REAPTIMEOUT_NODE    (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 { (void)(y); } 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->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
  * cachep->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 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->size -
                           sizeof(unsigned long long) -
                           REDZONE_ALIGN);
     return (unsigned long long *) (objp + cachep->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->size - BYTES_PER_WORD);
 }
 
 #else
 
 #define obj_offset(x)           0
 #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 or
  * overridden on the command line.
  */
 #define SLAB_MAX_ORDER_HI   1
 #define SLAB_MAX_ORDER_LO   0
 static int slab_max_order = SLAB_MAX_ORDER_LO;
 static bool slab_max_order_set __initdata;
 
 static inline void *index_to_obj(struct kmem_cache *cache,
                  const struct slab *slab, unsigned int idx)
 {
     return slab->s_mem + cache->size * idx;
 }
 
 #define BOOT_CPUCACHE_ENTRIES   1
 /* internal cache of cache description objs */
 static struct kmem_cache kmem_cache_boot = {
     .batchcount = 1,
     .limit = BOOT_CPUCACHE_ENTRIES,
     .shared = 1,
     .size = sizeof(struct kmem_cache),
     .name = "kmem_cache",
 };
 
 static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
 
 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
 {
     return this_cpu_ptr(cachep->cpu_cache);
 }
 
 /*
  * Calculate the number of objects and left-over bytes for a given buffer size.
  */
 static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size,
         slab_flags_t flags, size_t *left_over)
 {
     unsigned int num;
     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:
      *
      * - @buffer_size bytes for each object
      * - One freelist_idx_t for each object
      *
      * We don't need to consider alignment of freelist because
      * freelist will be at the end of slab page. The objects will be
      * at the correct alignment.
      *
      * 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_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) {
         num = slab_size / buffer_size;
         *left_over = slab_size % buffer_size;
     } else {
         num = slab_size / (buffer_size + sizeof(freelist_idx_t));
         *left_over = slab_size %
             (buffer_size + sizeof(freelist_idx_t));
     }
 
     return num;
 }
 
 #if DEBUG
 #define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
 
 static void __slab_error(const char *function, struct kmem_cache *cachep,
             char *msg)
 {
     pr_err("slab error in %s(): cache `%s': %s\n",
            function, cachep->name, msg);
     dump_stack();
     add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 #endif
 
 /*
  * 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 __init noaliencache_setup(char *s)
 {
     use_alien_caches = 0;
     return 1;
 }
 __setup("noaliencache", noaliencache_setup);
 
 static int __init slab_max_order_setup(char *str)
 {
     get_option(&str, &slab_max_order);
     slab_max_order = slab_max_order < 0 ? 0 :
                 min(slab_max_order, MAX_ORDER - 1);
     slab_max_order_set = true;
 
     return 1;
 }
 __setup("slab_max_order=", slab_max_order_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, slab_reap_node);
 
 static void init_reap_node(int cpu)
 {
     per_cpu(slab_reap_node, cpu) = next_node_in(cpu_to_mem(cpu),
                             node_online_map);
 }
 
 static void next_reap_node(void)
 {
     int node = __this_cpu_read(slab_reap_node);
 
     node = next_node_in(node, node_online_map);
     __this_cpu_write(slab_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 start_cpu_timer(int cpu)
 {
     struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
 
     if (reap_work->work.func == NULL) {
         init_reap_node(cpu);
         INIT_DEFERRABLE_WORK(reap_work, cache_reap);
         schedule_delayed_work_on(cpu, reap_work,
                     __round_jiffies_relative(HZ, cpu));
     }
 }
 
 static void init_arraycache(struct array_cache *ac, int limit, int batch)
 {
     if (ac) {
         ac->avail = 0;
         ac->limit = limit;
         ac->batchcount = batch;
         ac->touched = 0;
     }
 }
 
 static struct array_cache *alloc_arraycache(int node, int entries,
                         int batchcount, gfp_t gfp)
 {
     size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
     struct array_cache *ac = NULL;
 
     ac = kmalloc_node(memsize, gfp, node);
     /*
      * The array_cache structures contain pointers to free object.
      * However, when such objects are allocated or transferred to another
      * cache the pointers are not cleared and they could be counted as
      * valid references during a kmemleak scan. Therefore, kmemleak must
      * not scan such objects.
      */
     kmemleak_no_scan(ac);
     init_arraycache(ac, entries, batchcount);
     return ac;
 }
 
 static noinline void cache_free_pfmemalloc(struct kmem_cache *cachep,
                     struct slab *slab, void *objp)
 {
     struct kmem_cache_node *n;
     int slab_node;
     LIST_HEAD(list);
 
     slab_node = slab_nid(slab);
     n = get_node(cachep, slab_node);
 
     spin_lock(&n->list_lock);
     free_block(cachep, &objp, 1, slab_node, &list);
     spin_unlock(&n->list_lock);
 
     slabs_destroy(cachep, &list);
 }
 
 /*
  * 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 = min3(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;
     return nr;
 }
 
 /* &alien->lock must be held by alien callers. */
 static __always_inline void __free_one(struct array_cache *ac, void *objp)
 {
     /* Avoid trivial double-free. */
     if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
         WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
         return;
     ac->entry[ac->avail++] = objp;
 }
 
 #ifndef CONFIG_NUMA
 
 #define drain_alien_cache(cachep, alien) do { } while (0)
 #define reap_alien(cachep, n) do { } while (0)
 
 static inline struct alien_cache **alloc_alien_cache(int node,
                         int limit, gfp_t gfp)
 {
     return NULL;
 }
 
 static inline void free_alien_cache(struct alien_cache **ac_ptr)
 {
 }
 
 static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 {
     return 0;
 }
 
 static inline gfp_t gfp_exact_node(gfp_t flags)
 {
     return flags & ~__GFP_NOFAIL;
 }
 
 #else   /* CONFIG_NUMA */
 
 static struct alien_cache *__alloc_alien_cache(int node, int entries,
                         int batch, gfp_t gfp)
 {
     size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
     struct alien_cache *alc = NULL;
 
     alc = kmalloc_node(memsize, gfp, node);
     if (alc) {
         kmemleak_no_scan(alc);
         init_arraycache(&alc->ac, entries, batch);
         spin_lock_init(&alc->lock);
     }
     return alc;
 }
 
 static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
 {
     struct alien_cache **alc_ptr;
     int i;
 
     if (limit > 1)
         limit = 12;
     alc_ptr = kcalloc_node(nr_node_ids, sizeof(void *), gfp, node);
     if (!alc_ptr)
         return NULL;
 
     for_each_node(i) {
         if (i == node || !node_online(i))
             continue;
         alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
         if (!alc_ptr[i]) {
             for (i--; i >= 0; i--)
                 kfree(alc_ptr[i]);
             kfree(alc_ptr);
             return NULL;
         }
     }
     return alc_ptr;
 }
 
 static void free_alien_cache(struct alien_cache **alc_ptr)
 {
     int i;
 
     if (!alc_ptr)
         return;
     for_each_node(i)
         kfree(alc_ptr[i]);
     kfree(alc_ptr);
 }
 
 static void __drain_alien_cache(struct kmem_cache *cachep,
                 struct array_cache *ac, int node,
                 struct list_head *list)
 {
     struct kmem_cache_node *n = get_node(cachep, node);
 
     if (ac->avail) {
         spin_lock(&n->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 (n->shared)
             transfer_objects(n->shared, ac, ac->limit);
 
         free_block(cachep, ac->entry, ac->avail, node, list);
         ac->avail = 0;
         spin_unlock(&n->list_lock);
     }
 }
 
 /*
  * Called from cache_reap() to regularly drain alien caches round robin.
  */
 static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
 {
     int node = __this_cpu_read(slab_reap_node);
 
     if (n->alien) {
         struct alien_cache *alc = n->alien[node];
         struct array_cache *ac;
 
         if (alc) {
             ac = &alc->ac;
             if (ac->avail && spin_trylock_irq(&alc->lock)) {
                 LIST_HEAD(list);
 
                 __drain_alien_cache(cachep, ac, node, &list);
                 spin_unlock_irq(&alc->lock);
                 slabs_destroy(cachep, &list);
             }
         }
     }
 }
 
 static void drain_alien_cache(struct kmem_cache *cachep,
                 struct alien_cache **alien)
 {
     int i = 0;
     struct alien_cache *alc;
     struct array_cache *ac;
     unsigned long flags;
 
     for_each_online_node(i) {
         alc = alien[i];
         if (alc) {
             LIST_HEAD(list);
 
             ac = &alc->ac;
             spin_lock_irqsave(&alc->lock, flags);
             __drain_alien_cache(cachep, ac, i, &list);
             spin_unlock_irqrestore(&alc->lock, flags);
             slabs_destroy(cachep, &list);
         }
     }
 }
 
 static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
                 int node, int slab_node)
 {
     struct kmem_cache_node *n;
     struct alien_cache *alien = NULL;
     struct array_cache *ac;
     LIST_HEAD(list);
 
     n = get_node(cachep, node);
     STATS_INC_NODEFREES(cachep);
     if (n->alien && n->alien[slab_node]) {
         alien = n->alien[slab_node];
         ac = &alien->ac;
         spin_lock(&alien->lock);
         if (unlikely(ac->avail == ac->limit)) {
             STATS_INC_ACOVERFLOW(cachep);
             __drain_alien_cache(cachep, ac, slab_node, &list);
         }
         __free_one(ac, objp);
         spin_unlock(&alien->lock);
         slabs_destroy(cachep, &list);
     } else {
         n = get_node(cachep, slab_node);
         spin_lock(&n->list_lock);
         free_block(cachep, &objp, 1, slab_node, &list);
         spin_unlock(&n->list_lock);
         slabs_destroy(cachep, &list);
     }
     return 1;
 }
 
 static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 {
     int slab_node = slab_nid(virt_to_slab(objp));
     int node = numa_mem_id();
     /*
      * Make sure we are not freeing an object from another node to the array
      * cache on this cpu.
      */
     if (likely(node == slab_node))
         return 0;
 
     return __cache_free_alien(cachep, objp, node, slab_node);
 }
 
 /*
  * Construct gfp mask to allocate from a specific node but do not reclaim or
  * warn about failures.
  */
 static inline gfp_t gfp_exact_node(gfp_t flags)
 {
     return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
 }
 #endif
 
 static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
 {
     struct kmem_cache_node *n;
 
     /*
      * Set up the kmem_cache_node for cpu before we can
      * begin anything. Make sure some other cpu on this
      * node has not already allocated this
      */
     n = get_node(cachep, node);
     if (n) {
         spin_lock_irq(&n->list_lock);
         n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount +
                 cachep->num;
         spin_unlock_irq(&n->list_lock);
 
         return 0;
     }
 
     n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
     if (!n)
         return -ENOMEM;
 
     kmem_cache_node_init(n);
     n->next_reap = jiffies + REAPTIMEOUT_NODE +
             ((unsigned long)cachep) % REAPTIMEOUT_NODE;
 
     n->free_limit =
         (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num;
 
     /*
      * The kmem_cache_nodes don't come and go as CPUs
      * come and go.  slab_mutex provides sufficient
      * protection here.
      */
     cachep->node[node] = n;
 
     return 0;
 }
 
 #if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
 /*
  * Allocates and initializes node for a node on each slab cache, used for
  * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
  * will be allocated off-node since memory is not yet online for the new node.
  * When hotplugging memory or a cpu, existing nodes are not replaced if
  * already in use.
  *
  * Must hold slab_mutex.
  */
 static int init_cache_node_node(int node)
 {
     int ret;
     struct kmem_cache *cachep;
 
     list_for_each_entry(cachep, &slab_caches, list) {
         ret = init_cache_node(cachep, node, GFP_KERNEL);
         if (ret)
             return ret;
     }
 
     return 0;
 }
 #endif
 
 static int setup_kmem_cache_node(struct kmem_cache *cachep,
                 int node, gfp_t gfp, bool force_change)
 {
     int ret = -ENOMEM;
     struct kmem_cache_node *n;
     struct array_cache *old_shared = NULL;
     struct array_cache *new_shared = NULL;
     struct alien_cache **new_alien = NULL;
     LIST_HEAD(list);
 
     if (use_alien_caches) {
         new_alien = alloc_alien_cache(node, cachep->limit, gfp);
         if (!new_alien)
             goto fail;
     }
 
     if (cachep->shared) {
         new_shared = alloc_arraycache(node,
             cachep->shared * cachep->batchcount, 0xbaadf00d, gfp);
         if (!new_shared)
             goto fail;
     }
 
     ret = init_cache_node(cachep, node, gfp);
     if (ret)
         goto fail;
 
     n = get_node(cachep, node);
     spin_lock_irq(&n->list_lock);
     if (n->shared && force_change) {
         free_block(cachep, n->shared->entry,
                 n->shared->avail, node, &list);
         n->shared->avail = 0;
     }
 
     if (!n->shared || force_change) {
         old_shared = n->shared;
         n->shared = new_shared;
         new_shared = NULL;
     }
 
     if (!n->alien) {
         n->alien = new_alien;
         new_alien = NULL;
     }
 
     spin_unlock_irq(&n->list_lock);
     slabs_destroy(cachep, &list);
 
     /*
      * To protect lockless access to n->shared during irq disabled context.
      * If n->shared isn't NULL in irq disabled context, accessing to it is
      * guaranteed to be valid until irq is re-enabled, because it will be
      * freed after synchronize_rcu().
      */
     if (old_shared && force_change)
         synchronize_rcu();
 
 fail:
     kfree(old_shared);
     kfree(new_shared);
     free_alien_cache(new_alien);
 
     return ret;
 }
 
 #ifdef CONFIG_SMP
 
 static void cpuup_canceled(long cpu)
 {
     struct kmem_cache *cachep;
     struct kmem_cache_node *n = NULL;
     int node = cpu_to_mem(cpu);
     const struct cpumask *mask = cpumask_of_node(node);
 
     list_for_each_entry(cachep, &slab_caches, list) {
         struct array_cache *nc;
         struct array_cache *shared;
         struct alien_cache **alien;
         LIST_HEAD(list);
 
         n = get_node(cachep, node);
         if (!n)
             continue;
 
         spin_lock_irq(&n->list_lock);
 
         /* Free limit for this kmem_cache_node */
         n->free_limit -= cachep->batchcount;
 
         /* cpu is dead; no one can alloc from it. */
         nc = per_cpu_ptr(cachep->cpu_cache, cpu);
         free_block(cachep, nc->entry, nc->avail, node, &list);
         nc->avail = 0;
 
         if (!cpumask_empty(mask)) {
             spin_unlock_irq(&n->list_lock);
             goto free_slab;
         }
 
         shared = n->shared;
         if (shared) {
             free_block(cachep, shared->entry,
                    shared->avail, node, &list);
             n->shared = NULL;
         }
 
         alien = n->alien;
         n->alien = NULL;
 
         spin_unlock_irq(&n->list_lock);
 
         kfree(shared);
         if (alien) {
             drain_alien_cache(cachep, alien);
             free_alien_cache(alien);
         }
 
 free_slab:
         slabs_destroy(cachep, &list);
     }
     /*
      * 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, &slab_caches, list) {
         n = get_node(cachep, node);
         if (!n)
             continue;
         drain_freelist(cachep, n, INT_MAX);
     }
 }
 
 static int cpuup_prepare(long cpu)
 {
     struct kmem_cache *cachep;
     int node = cpu_to_mem(cpu);
     int err;
 
     /*
      * 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_cache_node and not this cpu's kmem_cache_node
      */
     err = init_cache_node_node(node);
     if (err < 0)
         goto bad;
 
     /*
      * Now we can go ahead with allocating the shared arrays and
      * array caches
      */
     list_for_each_entry(cachep, &slab_caches, list) {
         err = setup_kmem_cache_node(cachep, node, GFP_KERNEL, false);
         if (err)
             goto bad;
     }
 
     return 0;
 bad:
     cpuup_canceled(cpu);
     return -ENOMEM;
 }
 
 int slab_prepare_cpu(unsigned int cpu)
 {
     int err;
 
     mutex_lock(&slab_mutex);
     err = cpuup_prepare(cpu);
     mutex_unlock(&slab_mutex);
     return err;
 }
 
 /*
  * This is called for a failed online attempt and for a successful
  * offline.
  *
  * Even if all the cpus of a node are down, we don't free the
  * kmem_cache_node of any cache. This is 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 kmem_cache_node structure is usually allocated from
  * kmem_cache_create() and gets destroyed at kmem_cache_destroy().
  */
 int slab_dead_cpu(unsigned int cpu)
 {
     mutex_lock(&slab_mutex);
     cpuup_canceled(cpu);
     mutex_unlock(&slab_mutex);
     return 0;
 }
 #endif
 
 static int slab_online_cpu(unsigned int cpu)
 {
     start_cpu_timer(cpu);
     return 0;
 }
 
 static int slab_offline_cpu(unsigned int cpu)
 {
     /*
      * Shutdown cache reaper. Note that the slab_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_delayed_work_sync(&per_cpu(slab_reap_work, cpu));
     /* Now the cache_reaper is guaranteed to be not running. */
     per_cpu(slab_reap_work, cpu).work.func = NULL;
     return 0;
 }
 
 #if defined(CONFIG_NUMA)
 /*
  * Drains freelist for a node on each slab cache, used for memory hot-remove.
  * Returns -EBUSY if all objects cannot be drained so that the node is not
  * removed.
  *
  * Must hold slab_mutex.
  */
 static int __meminit drain_cache_node_node(int node)
 {
     struct kmem_cache *cachep;
     int ret = 0;
 
     list_for_each_entry(cachep, &slab_caches, list) {
         struct kmem_cache_node *n;
 
         n = get_node(cachep, node);
         if (!n)
             continue;
 
         drain_freelist(cachep, n, INT_MAX);
 
         if (!list_empty(&n->slabs_full) ||
             !list_empty(&n->slabs_partial)) {
             ret = -EBUSY;
             break;
         }
     }
     return ret;
 }
 
 static int __meminit slab_memory_callback(struct notifier_block *self,
                     unsigned long action, void *arg)
 {
     struct memory_notify *mnb = arg;
     int ret = 0;
     int nid;
 
     nid = mnb->status_change_nid;
     if (nid < 0)
         goto out;
 
     switch (action) {
     case MEM_GOING_ONLINE:
         mutex_lock(&slab_mutex);
         ret = init_cache_node_node(nid);
         mutex_unlock(&slab_mutex);
         break;
     case MEM_GOING_OFFLINE:
         mutex_lock(&slab_mutex);
         ret = drain_cache_node_node(nid);
         mutex_unlock(&slab_mutex);
         break;
     case MEM_ONLINE:
     case MEM_OFFLINE:
     case MEM_CANCEL_ONLINE:
     case MEM_CANCEL_OFFLINE:
         break;
     }
 out:
     return notifier_from_errno(ret);
 }
 #endif /* CONFIG_NUMA */
 
 /*
  * swap the static kmem_cache_node with kmalloced memory
  */
 static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list,
                 int nodeid)
 {
     struct kmem_cache_node *ptr;
 
     ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid);
     BUG_ON(!ptr);
 
     memcpy(ptr, list, sizeof(struct kmem_cache_node));
     /*
      * Do not assume that spinlocks can be initialized via memcpy:
      */
     spin_lock_init(&ptr->list_lock);
 
     MAKE_ALL_LISTS(cachep, ptr, nodeid);
     cachep->node[nodeid] = ptr;
 }
 
 /*
  * For setting up all the kmem_cache_node for cache whose buffer_size is same as
  * size of kmem_cache_node.
  */
 static void __init set_up_node(struct kmem_cache *cachep, int index)
 {
     int node;
 
     for_each_online_node(node) {
         cachep->node[node] = &init_kmem_cache_node[index + node];
         cachep->node[node]->next_reap = jiffies +
             REAPTIMEOUT_NODE +
             ((unsigned long)cachep) % REAPTIMEOUT_NODE;
     }
 }
 
 /*
  * Initialisation.  Called after the page allocator have been initialised and
  * before smp_init().
  */
 void __init kmem_cache_init(void)
 {
     int i;
 
     kmem_cache = &kmem_cache_boot;
 
     if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
         use_alien_caches = 0;
 
     for (i = 0; i < NUM_INIT_LISTS; i++)
         kmem_cache_node_init(&init_kmem_cache_node[i]);
 
     /*
      * Fragmentation resistance on low memory - only use bigger
      * page orders on machines with more than 32MB of memory if
      * not overridden on the command line.
      */
     if (!slab_max_order_set && totalram_pages() > (32 << 20) >> PAGE_SHIFT)
         slab_max_order = SLAB_MAX_ORDER_HI;
 
     /* Bootstrap is tricky, because several objects are allocated
      * from caches that do not exist yet:
      * 1) initialize the kmem_cache cache: it contains the struct
      *    kmem_cache structures of all caches, except kmem_cache itself:
      *    kmem_cache is statically allocated.
      *    Initially an __init data area is used for the head array and the
      *    kmem_cache_node 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 kmem_cache and the first
      *    kmalloc cache with kmalloc allocated arrays.
      * 5) Replace the __init data for kmem_cache_node for kmem_cache and
      *    the other cache's with kmalloc allocated memory.
      * 6) Resize the head arrays of the kmalloc caches to their final sizes.
      */
 
     /* 1) create the kmem_cache */
 
     /*
      * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
      */
     create_boot_cache(kmem_cache, "kmem_cache",
         offsetof(struct kmem_cache, node) +
                   nr_node_ids * sizeof(struct kmem_cache_node *),
                   SLAB_HWCACHE_ALIGN, 0, 0);
     list_add(&kmem_cache->list, &slab_caches);
     slab_state = PARTIAL;
 
     /*
      * Initialize the caches that provide memory for the  kmem_cache_node
      * structures first.  Without this, further allocations will bug.
      */
     kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
                 kmalloc_info[INDEX_NODE].name[KMALLOC_NORMAL],
                 kmalloc_info[INDEX_NODE].size,
                 ARCH_KMALLOC_FLAGS, 0,
                 kmalloc_info[INDEX_NODE].size);
     slab_state = PARTIAL_NODE;
     setup_kmalloc_cache_index_table();
 
     slab_early_init = 0;
 
     /* 5) Replace the bootstrap kmem_cache_node */
     {
         int nid;
 
         for_each_online_node(nid) {
             init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);
 
             init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE],
                       &init_kmem_cache_node[SIZE_NODE + nid], nid);
         }
     }
 
     create_kmalloc_caches(ARCH_KMALLOC_FLAGS);
 }
 
 void __init kmem_cache_init_late(void)
 {
     struct kmem_cache *cachep;
 
     /* 6) resize the head arrays to their final sizes */
     mutex_lock(&slab_mutex);
     list_for_each_entry(cachep, &slab_caches, list)
         if (enable_cpucache(cachep, GFP_NOWAIT))
             BUG();
     mutex_unlock(&slab_mutex);
 
     /* Done! */
     slab_state = FULL;
 
 #ifdef CONFIG_NUMA
     /*
      * Register a memory hotplug callback that initializes and frees
      * node.
      */
     hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
 #endif
 
     /*
      * 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 ret;
 
     /*
      * Register the timers that return unneeded pages to the page allocator
      */
     ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SLAB online",
                 slab_online_cpu, slab_offline_cpu);
     WARN_ON(ret < 0);
 
     return 0;
 }
 __initcall(cpucache_init);
 
 static noinline void
 slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
 {
 #if DEBUG
     struct kmem_cache_node *n;
     unsigned long flags;
     int node;
     static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
                       DEFAULT_RATELIMIT_BURST);
 
     if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
         return;
 
     pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
         nodeid, gfpflags, &gfpflags);
     pr_warn("  cache: %s, object size: %d, order: %d\n",
         cachep->name, cachep->size, cachep->gfporder);
 
     for_each_kmem_cache_node(cachep, node, n) {
         unsigned long total_slabs, free_slabs, free_objs;
 
         spin_lock_irqsave(&n->list_lock, flags);
         total_slabs = n->total_slabs;
         free_slabs = n->free_slabs;
         free_objs = n->free_objects;
         spin_unlock_irqrestore(&n->list_lock, flags);
 
         pr_warn("  node %d: slabs: %ld/%ld, objs: %ld/%ld\n",
             node, total_slabs - free_slabs, total_slabs,
             (total_slabs * cachep->num) - free_objs,
             total_slabs * cachep->num);
     }
 #endif
 }
 
 /*
  * Interface to system's page allocator. No need to hold the
  * kmem_cache_node ->list_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 struct slab *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
                                 int nodeid)
 {
     struct folio *folio;
     struct slab *slab;
 
     flags |= cachep->allocflags;
 
     folio = (struct folio *) __alloc_pages_node(nodeid, flags, cachep->gfporder);
     if (!folio) {
         slab_out_of_memory(cachep, flags, nodeid);
         return NULL;
     }
 
     slab = folio_slab(folio);
 
     account_slab(slab, cachep->gfporder, cachep, flags);
     __folio_set_slab(folio);
     /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
     if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0)))
         slab_set_pfmemalloc(slab);
 
     return slab;
 }
 
 /*
  * Interface to system's page release.
  */
 static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab)
 {
     int order = cachep->gfporder;
     struct folio *folio = slab_folio(slab);
 
     BUG_ON(!folio_test_slab(folio));
     __slab_clear_pfmemalloc(slab);
     __folio_clear_slab(folio);
     page_mapcount_reset(folio_page(folio, 0));
     folio->mapping = NULL;
 
     if (current->reclaim_state)
         current->reclaim_state->reclaimed_slab += 1 << order;
     unaccount_slab(slab, order, cachep);
     __free_pages(folio_page(folio, 0), order);
 }
 
 static void kmem_rcu_free(struct rcu_head *head)
 {
     struct kmem_cache *cachep;
     struct slab *slab;
 
     slab = container_of(head, struct slab, rcu_head);
     cachep = slab->slab_cache;
 
     kmem_freepages(cachep, slab);
 }
 
 #if DEBUG
 static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
 {
     if (debug_pagealloc_enabled_static() && OFF_SLAB(cachep) &&
         (cachep->size % PAGE_SIZE) == 0)
         return true;
 
     return false;
 }
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
 {
     if (!is_debug_pagealloc_cache(cachep))
         return;
 
     __kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
 }
 
 #else
 static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
                 int map) {}
 
 #endif
 
 static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
 {
     int size = cachep->object_size;
     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;
 
     pr_err("%03x: ", offset);
     for (i = 0; i < limit; i++) {
         if (data[offset + i] != POISON_FREE) {
             error = data[offset + i];
             bad_count++;
         }
     }
     print_hex_dump(KERN_CONT, "", 0, 16, 1,
             &data[offset], limit, 1);
 
     if (bad_count == 1) {
         error ^= POISON_FREE;
         if (!(error & (error - 1))) {
             pr_err("Single bit error detected. Probably bad RAM.\n");
 #ifdef CONFIG_X86
             pr_err("Run memtest86+ or a similar memory test tool.\n");
 #else
             pr_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) {
         pr_err("Redzone: 0x%llx/0x%llx\n",
                *dbg_redzone1(cachep, objp),
                *dbg_redzone2(cachep, objp));
     }
 
     if (cachep->flags & SLAB_STORE_USER)
         pr_err("Last user: (%pSR)\n", *dbg_userword(cachep, objp));
     realobj = (char *)objp + obj_offset(cachep);
     size = cachep->object_size;
     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;
 
     if (is_debug_pagealloc_cache(cachep))
         return;
 
     realobj = (char *)objp + obj_offset(cachep);
     size = cachep->object_size;
 
     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) {
                 pr_err("Slab corruption (%s): %s start=%px, len=%d\n",
                        print_tainted(), 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 *slab = virt_to_slab(objp);
         unsigned int objnr;
 
         objnr = obj_to_index(cachep, slab, objp);
         if (objnr) {
             objp = index_to_obj(cachep, slab, objnr - 1);
             realobj = (char *)objp + obj_offset(cachep);
             pr_err("Prev obj: start=%px, len=%d\n", realobj, size);
             print_objinfo(cachep, objp, 2);
         }
         if (objnr + 1 < cachep->num) {
             objp = index_to_obj(cachep, slab, objnr + 1);
             realobj = (char *)objp + obj_offset(cachep);
             pr_err("Next obj: start=%px, len=%d\n", realobj, size);
             print_objinfo(cachep, objp, 2);
         }
     }
 }
 #endif
 
 #if DEBUG
 static void slab_destroy_debugcheck(struct kmem_cache *cachep,
                         struct slab *slab)
 {
     int i;
 
     if (OBJFREELIST_SLAB(cachep) && cachep->flags & SLAB_POISON) {
         poison_obj(cachep, slab->freelist - obj_offset(cachep),
             POISON_FREE);
     }
 
     for (i = 0; i < cachep->num; i++) {
         void *objp = index_to_obj(cachep, slab, i);
 
         if (cachep->flags & SLAB_POISON) {
             check_poison_obj(cachep, objp);
             slab_kernel_map(cachep, objp, 1);
         }
         if (cachep->flags & SLAB_RED_ZONE) {
             if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
                 slab_error(cachep, "start of a freed object was overwritten");
             if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
                 slab_error(cachep, "end of a freed object was overwritten");
         }
     }
 }
 #else
 static void slab_destroy_debugcheck(struct kmem_cache *cachep,
                         struct slab *slab)
 {
 }
 #endif
 
 /**
  * slab_destroy - destroy and release all objects in a slab
  * @cachep: cache pointer being destroyed
  * @slab: slab 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
  * kmem_cache_node ->list_lock is not held/needed.
  */
 static void slab_destroy(struct kmem_cache *cachep, struct slab *slab)
 {
     void *freelist;
 
     freelist = slab->freelist;
     slab_destroy_debugcheck(cachep, slab);
     if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
         call_rcu(&slab->rcu_head, kmem_rcu_free);
     else
         kmem_freepages(cachep, slab);
 
     /*
      * From now on, we don't use freelist
      * although actual page can be freed in rcu context
      */
     if (OFF_SLAB(cachep))
         kmem_cache_free(cachep->freelist_cache, freelist);
 }
 
 /*
  * Update the size of the caches before calling slabs_destroy as it may
  * recursively call kfree.
  */
 static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list)
 {
     struct slab *slab, *n;
 
     list_for_each_entry_safe(slab, n, list, slab_list) {
         list_del(&slab->slab_list);
         slab_destroy(cachep, slab);
     }
 }
 
 /**
  * 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.
  * @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.
  *
  * Return: number of left-over bytes in a slab
  */
 static size_t calculate_slab_order(struct kmem_cache *cachep,
                 size_t size, slab_flags_t flags)
 {
     size_t left_over = 0;
     int gfporder;
 
     for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
         unsigned int num;
         size_t remainder;
 
         num = cache_estimate(gfporder, size, flags, &remainder);
         if (!num)
             continue;
 
         /* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
         if (num > SLAB_OBJ_MAX_NUM)
             break;
 
         if (flags & CFLGS_OFF_SLAB) {
             struct kmem_cache *freelist_cache;
             size_t freelist_size;
 
             freelist_size = num * sizeof(freelist_idx_t);
             freelist_cache = kmalloc_slab(freelist_size, 0u);
             if (!freelist_cache)
                 continue;
 
             /*
              * Needed to avoid possible looping condition
              * in cache_grow_begin()
              */
             if (OFF_SLAB(freelist_cache))
                 continue;
 
             /* check if off slab has enough benefit */
             if (freelist_cache->size > cachep->size / 2)
                 continue;
         }
 
         /* 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_max_order)
             break;
 
         /*
          * Acceptable internal fragmentation?
          */
         if (left_over * 8 <= (PAGE_SIZE << gfporder))
             break;
     }
     return left_over;
 }
 
 static struct array_cache __percpu *alloc_kmem_cache_cpus(
         struct kmem_cache *cachep, int entries, int batchcount)
 {
     int cpu;
     size_t size;
     struct array_cache __percpu *cpu_cache;
 
     size = sizeof(void *) * entries + sizeof(struct array_cache);
     cpu_cache = __alloc_percpu(size, sizeof(void *));
 
     if (!cpu_cache)
         return NULL;
 
     for_each_possible_cpu(cpu) {
         init_arraycache(per_cpu_ptr(cpu_cache, cpu),
                 entries, batchcount);
     }
 
     return cpu_cache;
 }
 
 static int __ref setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
     if (slab_state >= FULL)
         return enable_cpucache(cachep, gfp);
 
     cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1);
     if (!cachep->cpu_cache)
         return 1;
 
     if (slab_state == DOWN) {
         /* Creation of first cache (kmem_cache). */
         set_up_node(kmem_cache, CACHE_CACHE);
     } else if (slab_state == PARTIAL) {
         /* For kmem_cache_node */
         set_up_node(cachep, SIZE_NODE);
     } else {
         int node;
 
         for_each_online_node(node) {
             cachep->node[node] = kmalloc_node(
                 sizeof(struct kmem_cache_node), gfp, node);
             BUG_ON(!cachep->node[node]);
             kmem_cache_node_init(cachep->node[node]);
         }
     }
 
     cachep->node[numa_mem_id()]->next_reap =
             jiffies + REAPTIMEOUT_NODE +
             ((unsigned long)cachep) % REAPTIMEOUT_NODE;
 
     cpu_cache_get(cachep)->avail = 0;
     cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
     cpu_cache_get(cachep)->batchcount = 1;
     cpu_cache_get(cachep)->touched = 0;
     cachep->batchcount = 1;
     cachep->limit = BOOT_CPUCACHE_ENTRIES;
     return 0;
 }
 
 slab_flags_t kmem_cache_flags(unsigned int object_size,
     slab_flags_t flags, const char *name)
 {
     return flags;
 }
 
 struct kmem_cache *
 __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
            slab_flags_t flags, void (*ctor)(void *))
 {
     struct kmem_cache *cachep;
 
     cachep = find_mergeable(size, align, flags, name, ctor);
     if (cachep) {
         cachep->refcount++;
 
         /*
          * Adjust the object sizes so that we clear
          * the complete object on kzalloc.
          */
         cachep->object_size = max_t(int, cachep->object_size, size);
     }
     return cachep;
 }
 
 static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
             size_t size, slab_flags_t flags)
 {
     size_t left;
 
     cachep->num = 0;
 
     /*
      * If slab auto-initialization on free is enabled, store the freelist
      * off-slab, so that its contents don't end up in one of the allocated
      * objects.
      */
     if (unlikely(slab_want_init_on_free(cachep)))
         return false;
 
     if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
         return false;
 
     left = calculate_slab_order(cachep, size,
             flags | CFLGS_OBJFREELIST_SLAB);
     if (!cachep->num)
         return false;
 
     if (cachep->num * sizeof(freelist_idx_t) > cachep->object_size)
         return false;
 
     cachep->colour = left / cachep->colour_off;
 
     return true;
 }
 
 static bool set_off_slab_cache(struct kmem_cache *cachep,
             size_t size, slab_flags_t flags)
 {
     size_t left;
 
     cachep->num = 0;
 
     /*
      * Always use on-slab management when SLAB_NOLEAKTRACE
      * to avoid recursive calls into kmemleak.
      */
     if (flags & SLAB_NOLEAKTRACE)
         return false;
 
     /*
      * Size is large, assume best to place the slab management obj
      * off-slab (should allow better packing of objs).
      */
     left = calculate_slab_order(cachep, size, flags | CFLGS_OFF_SLAB);
     if (!cachep->num)
         return false;
 
     /*
      * 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 (left >= cachep->num * sizeof(freelist_idx_t))
         return false;
 
     cachep->colour = left / cachep->colour_off;
 
     return true;
 }
 
 static bool set_on_slab_cache(struct kmem_cache *cachep,
             size_t size, slab_flags_t flags)
 {
     size_t left;
 
     cachep->num = 0;
 
     left = calculate_slab_order(cachep, size, flags);
     if (!cachep->num)
         return false;
 
     cachep->colour = left / cachep->colour_off;
 
     return true;
 }
 
 /**
  * __kmem_cache_create - Create a cache.
  * @cachep: cache management descriptor
  * @flags: SLAB flags
  *
  * Returns a ptr to the cache on success, NULL on failure.
  * Cannot be called within an int, but can be interrupted.
  * The @ctor is run when new pages are allocated by the cache.
  *
  * 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.
  *
  * Return: a pointer to the created cache or %NULL in case of error
  */
 int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
 {
     size_t ralign = BYTES_PER_WORD;
     gfp_t gfp;
     int err;
     unsigned int size = cachep->size;
 
 #if DEBUG
 #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_TYPESAFE_BY_RCU))
         flags |= SLAB_POISON;
 #endif
 #endif
 
     /*
      * 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.
      */
     size = ALIGN(size, 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 = ALIGN(size, REDZONE_ALIGN);
     }
 
     /* 3) caller mandated alignment */
     if (ralign < cachep->align) {
         ralign = cachep->align;
     }
     /* disable debug if necessary */
     if (ralign > __alignof__(unsigned long long))
         flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
     /*
      * 4) Store it.
      */
     cachep->align = ralign;
     cachep->colour_off = cache_line_size();
     /* Offset must be a multiple of the alignment. */
     if (cachep->colour_off < cachep->align)
         cachep->colour_off = cachep->align;
 
     if (slab_is_available())
         gfp = GFP_KERNEL;
     else
         gfp = GFP_NOWAIT;
 
 #if DEBUG
 
     /*
      * 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;
     }
 #endif
 
     kasan_cache_create(cachep, &size, &flags);
 
     size = ALIGN(size, cachep->align);
     /*
      * We should restrict the number of objects in a slab to implement
      * byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
      */
     if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
         size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
 
 #if DEBUG
     /*
      * To activate debug pagealloc, off-slab management is necessary
      * requirement. In early phase of initialization, small sized slab
      * doesn't get initialized so it would not be possible. So, we need
      * to check size >= 256. It guarantees that all necessary small
      * sized slab is initialized in current slab initialization sequence.
      */
     if (debug_pagealloc_enabled_static() && (flags & SLAB_POISON) &&
         size >= 256 && cachep->object_size > cache_line_size()) {
         if (size < PAGE_SIZE || size % PAGE_SIZE == 0) {
             size_t tmp_size = ALIGN(size, PAGE_SIZE);
 
             if (set_off_slab_cache(cachep, tmp_size, flags)) {
                 flags |= CFLGS_OFF_SLAB;
                 cachep->obj_offset += tmp_size - size;
                 size = tmp_size;
                 goto done;
             }
         }
     }
 #endif
 
     if (set_objfreelist_slab_cache(cachep, size, flags)) {
         flags |= CFLGS_OBJFREELIST_SLAB;
         goto done;
     }
 
     if (set_off_slab_cache(cachep, size, flags)) {
         flags |= CFLGS_OFF_SLAB;
         goto done;
     }
 
     if (set_on_slab_cache(cachep, size, flags))
         goto done;
 
     return -E2BIG;
 
 done:
     cachep->freelist_size = cachep->num * sizeof(freelist_idx_t);
     cachep->flags = flags;
     cachep->allocflags = __GFP_COMP;
     if (flags & SLAB_CACHE_DMA)
         cachep->allocflags |= GFP_DMA;
     if (flags & SLAB_CACHE_DMA32)
         cachep->allocflags |= GFP_DMA32;
     if (flags & SLAB_RECLAIM_ACCOUNT)
         cachep->allocflags |= __GFP_RECLAIMABLE;
     cachep->size = size;
     cachep->reciprocal_buffer_size = reciprocal_value(size);
 
 #if DEBUG
     /*
      * If we're going to use the generic kernel_map_pages()
      * poisoning, then it's going to smash the contents of
      * the redzone and userword anyhow, so switch them off.
      */
     if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
         (cachep->flags & SLAB_POISON) &&
         is_debug_pagealloc_cache(cachep))
         cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
 #endif
 
     if (OFF_SLAB(cachep)) {
         cachep->freelist_cache =
             kmalloc_slab(cachep->freelist_size, 0u);
     }
 
     err = setup_cpu_cache(cachep, gfp);
     if (err) {
         __kmem_cache_release(cachep);
         return err;
     }
 
     return 0;
 }
 
 #if DEBUG
 static void check_irq_off(void)
 {
     BUG_ON(!irqs_disabled());
 }
 
 static void check_irq_on(void)
 {
     BUG_ON(irqs_disabled());
 }
 
 static void check_mutex_acquired(void)
 {
     BUG_ON(!mutex_is_locked(&slab_mutex));
 }
 
 static void check_spinlock_acquired(struct kmem_cache *cachep)
 {
 #ifdef CONFIG_SMP
     check_irq_off();
     assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock);
 #endif
 }
 
 static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
 {
 #ifdef CONFIG_SMP
     check_irq_off();
     assert_spin_locked(&get_node(cachep, node)->list_lock);
 #endif
 }
 
 #else
 #define check_irq_off() do { } while(0)
 #define check_irq_on()  do { } while(0)
 #define check_mutex_acquired()  do { } while(0)
 #define check_spinlock_acquired(x) do { } while(0)
 #define check_spinlock_acquired_node(x, y) do { } while(0)
 #endif
 
 static void drain_array_locked(struct kmem_cache *cachep, struct array_cache *ac,
                 int node, bool free_all, struct list_head *list)
 {
     int tofree;
 
     if (!ac || !ac->avail)
         return;
 
     tofree = free_all ? ac->avail : (ac->limit + 4) / 5;
     if (tofree > ac->avail)
         tofree = (ac->avail + 1) / 2;
 
     free_block(cachep, ac->entry, tofree, node, list);
     ac->avail -= tofree;
     memmove(ac->entry, &(ac->entry[tofree]), sizeof(void *) * ac->avail);
 }
 
 static void do_drain(void *arg)
 {
     struct kmem_cache *cachep = arg;
     struct array_cache *ac;
     int node = numa_mem_id();
     struct kmem_cache_node *n;
     LIST_HEAD(list);
 
     check_irq_off();
     ac = cpu_cache_get(cachep);
     n = get_node(cachep, node);
     spin_lock(&n->list_lock);
     free_block(cachep, ac->entry, ac->avail, node, &list);
     spin_unlock(&n->list_lock);
     ac->avail = 0;
     slabs_destroy(cachep, &list);
 }
 
 static void drain_cpu_caches(struct kmem_cache *cachep)
 {
     struct kmem_cache_node *n;
     int node;
     LIST_HEAD(list);
 
     on_each_cpu(do_drain, cachep, 1);
     check_irq_on();
     for_each_kmem_cache_node(cachep, node, n)
         if (n->alien)
             drain_alien_cache(cachep, n->alien);
 
     for_each_kmem_cache_node(cachep, node, n) {
         spin_lock_irq(&n->list_lock);
         drain_array_locked(cachep, n->shared, node, true, &list);
         spin_unlock_irq(&n->list_lock);
 
         slabs_destroy(cachep, &list);
     }
 }
 
 /*
  * 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_cache_node *n, int tofree)
 {
     struct list_head *p;
     int nr_freed;
     struct slab *slab;
 
     nr_freed = 0;
     while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
 
         spin_lock_irq(&n->list_lock);
         p = n->slabs_free.prev;
         if (p == &n->slabs_free) {
             spin_unlock_irq(&n->list_lock);
             goto out;
         }
 
         slab = list_entry(p, struct slab, slab_list);
         list_del(&slab->slab_list);
         n->free_slabs--;
         n->total_slabs--;
         /*
          * Safe to drop the lock. The slab is no longer linked
          * to the cache.
          */
         n->free_objects -= cache->num;
         spin_unlock_irq(&n->list_lock);
         slab_destroy(cache, slab);
         nr_freed++;
     }
 out:
     return nr_freed;
 }
 
 bool __kmem_cache_empty(struct kmem_cache *s)
 {
     int node;
     struct kmem_cache_node *n;
 
     for_each_kmem_cache_node(s, node, n)
         if (!list_empty(&n->slabs_full) ||
             !list_empty(&n->slabs_partial))
             return false;
     return true;
 }
 
 int __kmem_cache_shrink(struct kmem_cache *cachep)
 {
     int ret = 0;
     int node;
     struct kmem_cache_node *n;
 
     drain_cpu_caches(cachep);
 
     check_irq_on();
     for_each_kmem_cache_node(cachep, node, n) {
         drain_freelist(cachep, n, INT_MAX);
 
         ret += !list_empty(&n->slabs_full) ||
             !list_empty(&n->slabs_partial);
     }
     return (ret ? 1 : 0);
 }
 
 int __kmem_cache_shutdown(struct kmem_cache *cachep)
 {
     return __kmem_cache_shrink(cachep);
 }
 
 void __kmem_cache_release(struct kmem_cache *cachep)
 {
     int i;
     struct kmem_cache_node *n;
 
     cache_random_seq_destroy(cachep);
 
     free_percpu(cachep->cpu_cache);
 
     /* NUMA: free the node structures */
     for_each_kmem_cache_node(cachep, i, n) {
         kfree(n->shared);
         free_alien_cache(n->alien);
         kfree(n);
         cachep->node[i] = NULL;
     }
 }
 
 /*
  * Get the memory for a slab management obj.
  *
  * For a slab cache when the slab descriptor is off-slab, the
  * slab descriptor can't come from the same cache which is being created,
  * Because if it is the case, that means we defer the creation of
  * the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
  * And we eventually call down to __kmem_cache_create(), which
  * in turn looks up in the kmalloc_{dma,}_caches for the desired-size one.
  * This is a "chicken-and-egg" problem.
  *
  * So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
  * which are all initialized during kmem_cache_init().
  */
 static void *alloc_slabmgmt(struct kmem_cache *cachep,
                    struct slab *slab, int colour_off,
                    gfp_t local_flags, int nodeid)
 {
     void *freelist;
     void *addr = slab_address(slab);
 
     slab->s_mem = addr + colour_off;
     slab->active = 0;
 
     if (OBJFREELIST_SLAB(cachep))
         freelist = NULL;
     else if (OFF_SLAB(cachep)) {
         /* Slab management obj is off-slab. */
         freelist = kmem_cache_alloc_node(cachep->freelist_cache,
                           local_flags, nodeid);
     } else {
         /* We will use last bytes at the slab for freelist */
         freelist = addr + (PAGE_SIZE << cachep->gfporder) -
                 cachep->freelist_size;
     }
 
     return freelist;
 }
 
 static inline freelist_idx_t get_free_obj(struct slab *slab, unsigned int idx)
 {
     return ((freelist_idx_t *) slab->freelist)[idx];
 }
 
 static inline void set_free_obj(struct slab *slab,
                     unsigned int idx, freelist_idx_t val)
 {
     ((freelist_idx_t *)(slab->freelist))[idx] = val;
 }
 
 static void cache_init_objs_debug(struct kmem_cache *cachep, struct slab *slab)
 {
 #if DEBUG
     int i;
 
     for (i = 0; i < cachep->num; i++) {
         void *objp = index_to_obj(cachep, slab, i);
 
         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)) {
             kasan_unpoison_object_data(cachep,
                            objp + obj_offset(cachep));
             cachep->ctor(objp + obj_offset(cachep));
             kasan_poison_object_data(
                 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");
         }
         /* need to poison the objs? */
         if (cachep->flags & SLAB_POISON) {
             poison_obj(cachep, objp, POISON_FREE);
             slab_kernel_map(cachep, objp, 0);
         }
     }
 #endif
 }
 
 #ifdef CONFIG_SLAB_FREELIST_RANDOM
 /* Hold information during a freelist initialization */
 union freelist_init_state {
     struct {
         unsigned int pos;
         unsigned int *list;
         unsigned int count;
     };
     struct rnd_state rnd_state;
 };
 
 /*
  * Initialize the state based on the randomization method available.
  * return true if the pre-computed list is available, false otherwise.
  */
 static bool freelist_state_initialize(union freelist_init_state *state,
                 struct kmem_cache *cachep,
                 unsigned int count)
 {
     bool ret;
     unsigned int rand;
 
     /* Use best entropy available to define a random shift */
     rand = get_random_int();
 
     /* Use a random state if the pre-computed list is not available */
     if (!cachep->random_seq) {
         prandom_seed_state(&state->rnd_state, rand);
         ret = false;
     } else {
         state->list = cachep->random_seq;
         state->count = count;
         state->pos = rand % count;
         ret = true;
     }
     return ret;
 }
 
 /* Get the next entry on the list and randomize it using a random shift */
 static freelist_idx_t next_random_slot(union freelist_init_state *state)
 {
     if (state->pos >= state->count)
         state->pos = 0;
     return state->list[state->pos++];
 }
 
 /* Swap two freelist entries */
 static void swap_free_obj(struct slab *slab, unsigned int a, unsigned int b)
 {
     swap(((freelist_idx_t *) slab->freelist)[a],
         ((freelist_idx_t *) slab->freelist)[b]);
 }
 
 /*
  * Shuffle the freelist initialization state based on pre-computed lists.
  * return true if the list was successfully shuffled, false otherwise.
  */
 static bool shuffle_freelist(struct kmem_cache *cachep, struct slab *slab)
 {
     unsigned int objfreelist = 0, i, rand, count = cachep->num;
     union freelist_init_state state;
     bool precomputed;
 
     if (count < 2)
         return false;
 
     precomputed = freelist_state_initialize(&state, cachep, count);
 
     /* Take a random entry as the objfreelist */
     if (OBJFREELIST_SLAB(cachep)) {
         if (!precomputed)
             objfreelist = count - 1;
         else
             objfreelist = next_random_slot(&state);
         slab->freelist = index_to_obj(cachep, slab, objfreelist) +
                         obj_offset(cachep);
         count--;
     }
 
     /*
      * On early boot, generate the list dynamically.
      * Later use a pre-computed list for speed.
      */
     if (!precomputed) {
         for (i = 0; i < count; i++)
             set_free_obj(slab, i, i);
 
         /* Fisher-Yates shuffle */
         for (i = count - 1; i > 0; i--) {
             rand = prandom_u32_state(&state.rnd_state);
             rand %= (i + 1);
             swap_free_obj(slab, i, rand);
         }
     } else {
         for (i = 0; i < count; i++)
             set_free_obj(slab, i, next_random_slot(&state));
     }
 
     if (OBJFREELIST_SLAB(cachep))
         set_free_obj(slab, cachep->num - 1, objfreelist);
 
     return true;
 }
 #else
 static inline bool shuffle_freelist(struct kmem_cache *cachep,
                 struct slab *slab)
 {
     return false;
 }
 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
 
 static void cache_init_objs(struct kmem_cache *cachep,
                 struct slab *slab)
 {
     int i;
     void *objp;
     bool shuffled;
 
     cache_init_objs_debug(cachep, slab);
 
     /* Try to randomize the freelist if enabled */
     shuffled = shuffle_freelist(cachep, slab);
 
     if (!shuffled && OBJFREELIST_SLAB(cachep)) {
         slab->freelist = index_to_obj(cachep, slab, cachep->num - 1) +
                         obj_offset(cachep);
     }
 
     for (i = 0; i < cachep->num; i++) {
         objp = index_to_obj(cachep, slab, i);
         objp = kasan_init_slab_obj(cachep, objp);
 
         /* constructor could break poison info */
         if (DEBUG == 0 && cachep->ctor) {
             kasan_unpoison_object_data(cachep, objp);
             cachep->ctor(objp);
             kasan_poison_object_data(cachep, objp);
         }
 
         if (!shuffled)
             set_free_obj(slab, i, i);
     }
 }
 
 static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slab)
 {
     void *objp;
 
     objp = index_to_obj(cachep, slab, get_free_obj(slab, slab->active));
     slab->active++;
 
     return objp;
 }
 
 static void slab_put_obj(struct kmem_cache *cachep,
             struct slab *slab, void *objp)
 {
     unsigned int objnr = obj_to_index(cachep, slab, objp);
 #if DEBUG
     unsigned int i;
 
     /* Verify double free bug */
     for (i = slab->active; i < cachep->num; i++) {
         if (get_free_obj(slab, i) == objnr) {
             pr_err("slab: double free detected in cache '%s', objp %px\n",
                    cachep->name, objp);
             BUG();
         }
     }
 #endif
     slab->active--;
     if (!slab->freelist)
         slab->freelist = objp + obj_offset(cachep);
 
     set_free_obj(slab, slab->active, objnr);
 }
 
 /*
  * 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 struct slab *cache_grow_begin(struct kmem_cache *cachep,
                 gfp_t flags, int nodeid)
 {
     void *freelist;
     size_t offset;
     gfp_t local_flags;
     int slab_node;
     struct kmem_cache_node *n;
     struct slab *slab;
 
     /*
      * Be lazy and only check for valid flags here,  keeping it out of the
      * critical path in kmem_cache_alloc().
      */
     if (unlikely(flags & GFP_SLAB_BUG_MASK))
         flags = kmalloc_fix_flags(flags);
 
     WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
     local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
     check_irq_off();
     if (gfpflags_allow_blocking(local_flags))
         local_irq_enable();
 
     /*
      * Get mem for the objs.  Attempt to allocate a physical page from
      * 'nodeid'.
      */
     slab = kmem_getpages(cachep, local_flags, nodeid);
     if (!slab)
         goto failed;
 
     slab_node = slab_nid(slab);
     n = get_node(cachep, slab_node);
 
     /* Get colour for the slab, and cal the next value. */
     n->colour_next++;
     if (n->colour_next >= cachep->colour)
         n->colour_next = 0;
 
     offset = n->colour_next;
     if (offset >= cachep->colour)
         offset = 0;
 
     offset *= cachep->colour_off;
 
     /*
      * Call kasan_poison_slab() before calling alloc_slabmgmt(), so
      * page_address() in the latter returns a non-tagged pointer,
      * as it should be for slab pages.
      */
     kasan_poison_slab(slab);
 
     /* Get slab management. */
     freelist = alloc_slabmgmt(cachep, slab, offset,
             local_flags & ~GFP_CONSTRAINT_MASK, slab_node);
     if (OFF_SLAB(cachep) && !freelist)
         goto opps1;
 
     slab->slab_cache = cachep;
     slab->freelist = freelist;
 
     cache_init_objs(cachep, slab);
 
     if (gfpflags_allow_blocking(local_flags))
         local_irq_disable();
 
     return slab;
 
 opps1:
     kmem_freepages(cachep, slab);
 failed:
     if (gfpflags_allow_blocking(local_flags))
         local_irq_disable();
     return NULL;
 }
 
 static void cache_grow_end(struct kmem_cache *cachep, struct slab *slab)
 {
     struct kmem_cache_node *n;
     void *list = NULL;
 
     check_irq_off();
 
     if (!slab)
         return;
 
     INIT_LIST_HEAD(&slab->slab_list);
     n = get_node(cachep, slab_nid(slab));
 
     spin_lock(&n->list_lock);
     n->total_slabs++;
     if (!slab->active) {
         list_add_tail(&slab->slab_list, &n->slabs_free);
         n->free_slabs++;
     } else
         fixup_slab_list(cachep, n, slab, &list);
 
     STATS_INC_GROWN(cachep);
     n->free_objects += cachep->num - slab->active;
     spin_unlock(&n->list_lock);
 
     fixup_objfreelist_debug(cachep, &list);
 }
 
 #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)) {
         pr_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");
 
     pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
            obj, redzone1, redzone2);
 }
 
 static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
                    unsigned long caller)
 {
     unsigned int objnr;
     struct slab *slab;
 
     BUG_ON(virt_to_cache(objp) != cachep);
 
     objp -= obj_offset(cachep);
     kfree_debugcheck(objp);
     slab = virt_to_slab(objp);
 
     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) = (void *)caller;
 
     objnr = obj_to_index(cachep, slab, objp);
 
     BUG_ON(objnr >= cachep->num);
     BUG_ON(objp != index_to_obj(cachep, slab, objnr));
 
     if (cachep->flags & SLAB_POISON) {
         poison_obj(cachep, objp, POISON_FREE);
         slab_kernel_map(cachep, objp, 0);
     }
     return objp;
 }
 
 #else
 #define kfree_debugcheck(x) do { } while(0)
 #define cache_free_debugcheck(x, objp, z) (objp)
 #endif
 
 static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
                         void **list)
 {
 #if DEBUG
     void *next = *list;
     void *objp;
 
     while (next) {
         objp = next - obj_offset(cachep);
         next = *(void **)next;
         poison_obj(cachep, objp, POISON_FREE);
     }
 #endif
 }
 
 static inline void fixup_slab_list(struct kmem_cache *cachep,
                 struct kmem_cache_node *n, struct slab *slab,
                 void **list)
 {
     /* move slabp to correct slabp list: */
     list_del(&slab->slab_list);
     if (slab->active == cachep->num) {
         list_add(&slab->slab_list, &n->slabs_full);
         if (OBJFREELIST_SLAB(cachep)) {
 #if DEBUG
             /* Poisoning will be done without holding the lock */
             if (cachep->flags & SLAB_POISON) {
                 void **objp = slab->freelist;
 
                 *objp = *list;
                 *list = objp;
             }
 #endif
             slab->freelist = NULL;
         }
     } else
         list_add(&slab->slab_list, &n->slabs_partial);
 }
 
 /* Try to find non-pfmemalloc slab if needed */
 static noinline struct slab *get_valid_first_slab(struct kmem_cache_node *n,
                     struct slab *slab, bool pfmemalloc)
 {
     if (!slab)
         return NULL;
 
     if (pfmemalloc)
         return slab;
 
     if (!slab_test_pfmemalloc(slab))
         return slab;
 
     /* No need to keep pfmemalloc slab if we have enough free objects */
     if (n->free_objects > n->free_limit) {
         slab_clear_pfmemalloc(slab);
         return slab;
     }
 
     /* Move pfmemalloc slab to the end of list to speed up next search */
     list_del(&slab->slab_list);
     if (!slab->active) {
         list_add_tail(&slab->slab_list, &n->slabs_free);
         n->free_slabs++;
     } else
         list_add_tail(&slab->slab_list, &n->slabs_partial);
 
     list_for_each_entry(slab, &n->slabs_partial, slab_list) {
         if (!slab_test_pfmemalloc(slab))
             return slab;
     }
 
     n->free_touched = 1;
     list_for_each_entry(slab, &n->slabs_free, slab_list) {
         if (!slab_test_pfmemalloc(slab)) {
             n->free_slabs--;
             return slab;
         }
     }
 
     return NULL;
 }
 
 static struct slab *get_first_slab(struct kmem_cache_node *n, bool pfmemalloc)
 {
     struct slab *slab;
 
     assert_spin_locked(&n->list_lock);
     slab = list_first_entry_or_null(&n->slabs_partial, struct slab,
                     slab_list);
     if (!slab) {
         n->free_touched = 1;
         slab = list_first_entry_or_null(&n->slabs_free, struct slab,
                         slab_list);
         if (slab)
             n->free_slabs--;
     }
 
     if (sk_memalloc_socks())
         slab = get_valid_first_slab(n, slab, pfmemalloc);
 
     return slab;
 }
 
 static noinline void *cache_alloc_pfmemalloc(struct kmem_cache *cachep,
                 struct kmem_cache_node *n, gfp_t flags)
 {
     struct slab *slab;
     void *obj;
     void *list = NULL;
 
     if (!gfp_pfmemalloc_allowed(flags))
         return NULL;
 
     spin_lock(&n->list_lock);
     slab = get_first_slab(n, true);
     if (!slab) {
         spin_unlock(&n->list_lock);
         return NULL;
     }
 
     obj = slab_get_obj(cachep, slab);
     n->free_objects--;
 
     fixup_slab_list(cachep, n, slab, &list);
 
     spin_unlock(&n->list_lock);
     fixup_objfreelist_debug(cachep, &list);
 
     return obj;
 }
 
 /*
  * Slab list should be fixed up by fixup_slab_list() for existing slab
  * or cache_grow_end() for new slab
  */
 static __always_inline int alloc_block(struct kmem_cache *cachep,
         struct array_cache *ac, struct slab *slab, int batchcount)
 {
     /*
      * There must be at least one object available for
      * allocation.
      */
     BUG_ON(slab->active >= cachep->num);
 
     while (slab->active < cachep->num && batchcount--) {
         STATS_INC_ALLOCED(cachep);
         STATS_INC_ACTIVE(cachep);
         STATS_SET_HIGH(cachep);
 
         ac->entry[ac->avail++] = slab_get_obj(cachep, slab);
     }
 
     return batchcount;
 }
 
 static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
 {
     int batchcount;
     struct kmem_cache_node *n;
     struct array_cache *ac, *shared;
     int node;
     void *list = NULL;
     struct slab *slab;
 
     check_irq_off();
     node = numa_mem_id();
 
     ac = cpu_cache_get(cachep);
     batchcount = ac->batchcount;
     if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
         /*
          * If there was little recent activity on this cache, then
          * perform only a partial refill.  Otherwise we could generate
          * refill bouncing.
          */
         batchcount = BATCHREFILL_LIMIT;
     }
     n = get_node(cachep, node);
 
     BUG_ON(ac->avail > 0 || !n);
     shared = READ_ONCE(n->shared);
     if (!n->free_objects && (!shared || !shared->avail))
         goto direct_grow;
 
     spin_lock(&n->list_lock);
     shared = READ_ONCE(n->shared);
 
     /* See if we can refill from the shared array */
     if (shared && transfer_objects(ac, shared, batchcount)) {
         shared->touched = 1;
         goto alloc_done;
     }
 
     while (batchcount > 0) {
         /* Get slab alloc is to come from. */
         slab = get_first_slab(n, false);
         if (!slab)
             goto must_grow;
 
         check_spinlock_acquired(cachep);
 
         batchcount = alloc_block(cachep, ac, slab, batchcount);
         fixup_slab_list(cachep, n, slab, &list);
     }
 
 must_grow:
     n->free_objects -= ac->avail;
 alloc_done:
     spin_unlock(&n->list_lock);
     fixup_objfreelist_debug(cachep, &list);
 
 direct_grow:
     if (unlikely(!ac->avail)) {
         /* Check if we can use obj in pfmemalloc slab */
         if (sk_memalloc_socks()) {
             void *obj = cache_alloc_pfmemalloc(cachep, n, flags);
 
             if (obj)
                 return obj;
         }
 
         slab = cache_grow_begin(cachep, gfp_exact_node(flags), node);
 
         /*
          * cache_grow_begin() can reenable interrupts,
          * then ac could change.
          */
         ac = cpu_cache_get(cachep);
         if (!ac->avail && slab)
             alloc_block(cachep, ac, slab, batchcount);
         cache_grow_end(cachep, slab);
 
         if (!ac->avail)
             return NULL;
     }
     ac->touched = 1;
 
     return ac->entry[--ac->avail];
 }
 
 #if DEBUG
 static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
                 gfp_t flags, void *objp, unsigned long caller)
 {
     WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
     if (!objp || is_kfence_address(objp))
         return objp;
     if (cachep->flags & SLAB_POISON) {
         check_poison_obj(cachep, objp);
         slab_kernel_map(cachep, objp, 1);
         poison_obj(cachep, objp, POISON_INUSE);
     }
     if (cachep->flags & SLAB_STORE_USER)
         *dbg_userword(cachep, objp) = (void *)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");
             pr_err("%px: 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;
     }
 
     objp += obj_offset(cachep);
     if (cachep->ctor && cachep->flags & SLAB_POISON)
         cachep->ctor(objp);
     if ((unsigned long)objp & (arch_slab_minalign() - 1)) {
         pr_err("0x%px: not aligned to arch_slab_minalign()=%u\n", objp,
                arch_slab_minalign());
     }
     return objp;
 }
 #else
 #define cache_alloc_debugcheck_after(a, b, objp, d) (objp)
 #endif
 
 static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
     void *objp;
     struct array_cache *ac;
 
     check_irq_off();
 
     ac = cpu_cache_get(cachep);
     if (likely(ac->avail)) {
         ac->touched = 1;
         objp = ac->entry[--ac->avail];
 
         STATS_INC_ALLOCHIT(cachep);
         goto out;
     }
 
     STATS_INC_ALLOCMISS(cachep);
     objp = cache_alloc_refill(cachep, flags);
     /*
      * the 'ac' may be updated by cache_alloc_refill(),
      * and kmemleak_erase() requires its correct value.
      */
     ac = cpu_cache_get(cachep);
 
 out:
     /*
      * To avoid a false negative, if an object that is in one of the
      * per-CPU caches is leaked, we need to make sure kmemleak doesn't
      * treat the array pointers as a reference to the object.
      */
     if (objp)
         kmemleak_erase(&ac->entry[ac->avail]);
     return objp;
 }
 
 #ifdef CONFIG_NUMA
 static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
 
 /*
  * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
  *
  * If we are in_interrupt, then process context, including cpusets and
  * mempolicy, may not apply and should not be used for allocation policy.
  */
 static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
     int nid_alloc, nid_here;
 
     if (in_interrupt() || (flags & __GFP_THISNODE))
         return NULL;
     nid_alloc = nid_here = numa_mem_id();
     if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
         nid_alloc = cpuset_slab_spread_node();
     else if (current->mempolicy)
         nid_alloc = mempolicy_slab_node();
     if (nid_alloc != nid_here)
         return ____cache_alloc_node(cachep, flags, nid_alloc);
     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 node 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)
 {
     struct zonelist *zonelist;
     struct zoneref *z;
     struct zone *zone;
     enum zone_type highest_zoneidx = gfp_zone(flags);
     void *obj = NULL;
     struct slab *slab;
     int nid;
     unsigned int cpuset_mems_cookie;
 
     if (flags & __GFP_THISNODE)
         return NULL;
 
 retry_cpuset:
     cpuset_mems_cookie = read_mems_allowed_begin();
     zonelist = node_zonelist(mempolicy_slab_node(), flags);
 
 retry:
     /*
      * Look through allowed nodes for objects available
      * from existing per node queues.
      */
     for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) {
         nid = zone_to_nid(zone);
 
         if (cpuset_zone_allowed(zone, flags) &&
             get_node(cache, nid) &&
             get_node(cache, nid)->free_objects) {
                 obj = ____cache_alloc_node(cache,
                     gfp_exact_node(flags), nid);
                 if (obj)
                     break;
         }
     }
 
     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.
          */
         slab = cache_grow_begin(cache, flags, numa_mem_id());
         cache_grow_end(cache, slab);
         if (slab) {
             nid = slab_nid(slab);
             obj = ____cache_alloc_node(cache,
                 gfp_exact_node(flags), nid);
 
             /*
              * Another processor may allocate the objects in
              * the slab since we are not holding any locks.
              */
             if (!obj)
                 goto retry;
         }
     }
 
     if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
         goto retry_cpuset;
     return obj;
 }
 
 /*
  * An interface to enable slab creation on nodeid
  */
 static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
                 int nodeid)
 {
     struct slab *slab;
     struct kmem_cache_node *n;
     void *obj = NULL;
     void *list = NULL;
 
     VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
     n = get_node(cachep, nodeid);
     BUG_ON(!n);
 
     check_irq_off();
     spin_lock(&n->list_lock);
     slab = get_first_slab(n, false);
     if (!slab)
         goto must_grow;
 
     check_spinlock_acquired_node(cachep, nodeid);
 
     STATS_INC_NODEALLOCS(cachep);
     STATS_INC_ACTIVE(cachep);
     STATS_SET_HIGH(cachep);
 
     BUG_ON(slab->active == cachep->num);
 
     obj = slab_get_obj(cachep, slab);
     n->free_objects--;
 
     fixup_slab_list(cachep, n, slab, &list);
 
     spin_unlock(&n->list_lock);
     fixup_objfreelist_debug(cachep, &list);
     return obj;
 
 must_grow:
     spin_unlock(&n->list_lock);
     slab = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid);
     if (slab) {
         /* This slab isn't counted yet so don't update free_objects */
         obj = slab_get_obj(cachep, slab);
     }
     cache_grow_end(cachep, slab);
 
     return obj ? obj : fallback_alloc(cachep, flags);
 }
 
 static __always_inline void *
 slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_size,
            unsigned long caller)
 {
     unsigned long save_flags;
     void *ptr;
     int slab_node = numa_mem_id();
     struct obj_cgroup *objcg = NULL;
     bool init = false;
 
     flags &= gfp_allowed_mask;
     cachep = slab_pre_alloc_hook(cachep, NULL, &objcg, 1, flags);
     if (unlikely(!cachep))
         return NULL;
 
     ptr = kfence_alloc(cachep, orig_size, flags);
     if (unlikely(ptr))
         goto out_hooks;
 
     local_irq_save(save_flags);
 
     if (nodeid == NUMA_NO_NODE)
         nodeid = slab_node;
 
     if (unlikely(!get_node(cachep, nodeid))) {
         /* Node not bootstrapped yet */
         ptr = fallback_alloc(cachep, flags);
         goto out;
     }
 
     if (nodeid == slab_node) {
         /*
          * 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);
         if (ptr)
             goto out;
     }
     /* ___cache_alloc_node can fall back to other nodes */
     ptr = ____cache_alloc_node(cachep, flags, nodeid);
 out:
     local_irq_restore(save_flags);
     ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
     init = slab_want_init_on_alloc(flags, cachep);
 
 out_hooks:
     slab_post_alloc_hook(cachep, objcg, flags, 1, &ptr, init);
     return ptr;
 }
 
 static __always_inline void *
 __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
 {
     void *objp;
 
     if (current->mempolicy || cpuset_do_slab_mem_spread()) {
         objp = alternate_node_alloc(cache, flags);
         if (objp)
             goto out;
     }
     objp = ____cache_alloc(cache, flags);
 
     /*
      * 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, numa_mem_id());
 
 out:
     return objp;
 }
 #else
 
 static __always_inline void *
 __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
     return ____cache_alloc(cachep, flags);
 }
 
 #endif /* CONFIG_NUMA */
 
 static __always_inline void *
 slab_alloc(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags,
        size_t orig_size, unsigned long caller)
 {
     unsigned long save_flags;
     void *objp;
     struct obj_cgroup *objcg = NULL;
     bool init = false;
 
     flags &= gfp_allowed_mask;
     cachep = slab_pre_alloc_hook(cachep, lru, &objcg, 1, flags);
     if (unlikely(!cachep))
         return NULL;
 
     objp = kfence_alloc(cachep, orig_size, flags);
     if (unlikely(objp))
         goto out;
 
     local_irq_save(save_flags);
     objp = __do_cache_alloc(cachep, flags);
     local_irq_restore(save_flags);
     objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
     prefetchw(objp);
     init = slab_want_init_on_alloc(flags, cachep);
 
 out:
     slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init);
     return objp;
 }
 
 /*
  * Caller needs to acquire correct kmem_cache_node's list_lock
  * @list: List of detached free slabs should be freed by caller
  */
 static void free_block(struct kmem_cache *cachep, void **objpp,
             int nr_objects, int node, struct list_head *list)
 {
     int i;
     struct kmem_cache_node *n = get_node(cachep, node);
     struct slab *slab;
 
     n->free_objects += nr_objects;
 
     for (i = 0; i < nr_objects; i++) {
         void *objp;
         struct slab *slab;
 
         objp = objpp[i];
 
         slab = virt_to_slab(objp);
         list_del(&slab->slab_list);
         check_spinlock_acquired_node(cachep, node);
         slab_put_obj(cachep, slab, objp);
         STATS_DEC_ACTIVE(cachep);
 
         /* fixup slab chains */
         if (slab->active == 0) {
             list_add(&slab->slab_list, &n->slabs_free);
             n->free_slabs++;
         } 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(&slab->slab_list, &n->slabs_partial);
         }
     }
 
     while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
         n->free_objects -= cachep->num;
 
         slab = list_last_entry(&n->slabs_free, struct slab, slab_list);
         list_move(&slab->slab_list, list);
         n->free_slabs--;
         n->total_slabs--;
     }
 }
 
 static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
 {
     int batchcount;
     struct kmem_cache_node *n;
     int node = numa_mem_id();
     LIST_HEAD(list);
 
     batchcount = ac->batchcount;
 
     check_irq_off();
     n = get_node(cachep, node);
     spin_lock(&n->list_lock);
     if (n->shared) {
         struct array_cache *shared_array = n->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, &list);
 free_done:
 #if STATS
     {
         int i = 0;
         struct slab *slab;
 
         list_for_each_entry(slab, &n->slabs_free, slab_list) {
             BUG_ON(slab->active);
 
             i++;
         }
         STATS_SET_FREEABLE(cachep, i);
     }
 #endif
     spin_unlock(&n->list_lock);
     ac->avail -= batchcount;
     memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
     slabs_destroy(cachep, &list);
 }
 
 /*
  * 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 __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
                      unsigned long caller)
 {
     bool init;
 
     memcg_slab_free_hook(cachep, virt_to_slab(objp), &objp, 1);
 
     if (is_kfence_address(objp)) {
         kmemleak_free_recursive(objp, cachep->flags);
         __kfence_free(objp);
         return;
     }
 
     /*
      * As memory initialization might be integrated into KASAN,
      * kasan_slab_free and initialization memset must be
      * kept together to avoid discrepancies in behavior.
      */
     init = slab_want_init_on_free(cachep);
     if (init && !kasan_has_integrated_init())
         memset(objp, 0, cachep->object_size);
     /* KASAN might put objp into memory quarantine, delaying its reuse. */
     if (kasan_slab_free(cachep, objp, init))
         return;
 
     /* Use KCSAN to help debug racy use-after-free. */
     if (!(cachep->flags & SLAB_TYPESAFE_BY_RCU))
         __kcsan_check_access(objp, cachep->object_size,
                      KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
 
     ___cache_free(cachep, objp, caller);
 }
 
 void ___cache_free(struct kmem_cache *cachep, void *objp,
         unsigned long caller)
 {
     struct array_cache *ac = cpu_cache_get(cachep);
 
     check_irq_off();
     kmemleak_free_recursive(objp, cachep->flags);
     objp = cache_free_debugcheck(cachep, objp, caller);
 
     /*
      * 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 (nr_online_nodes > 1 && cache_free_alien(cachep, objp))
         return;
 
     if (ac->avail < ac->limit) {
         STATS_INC_FREEHIT(cachep);
     } else {
         STATS_INC_FREEMISS(cachep);
         cache_flusharray(cachep, ac);
     }
 
     if (sk_memalloc_socks()) {
         struct slab *slab = virt_to_slab(objp);
 
         if (unlikely(slab_test_pfmemalloc(slab))) {
             cache_free_pfmemalloc(cachep, slab, objp);
             return;
         }
     }
 
     __free_one(ac, objp);
 }
 
 static __always_inline
 void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
                  gfp_t flags)
 {
     void *ret = slab_alloc(cachep, lru, flags, cachep->object_size, _RET_IP_);
 
     trace_kmem_cache_alloc(_RET_IP_, ret, cachep,
                    cachep->object_size, cachep->size, flags);
 
     return ret;
 }
 
 /**
  * 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.
  *
  * Return: pointer to the new object or %NULL in case of error
  */
 void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
     return __kmem_cache_alloc_lru(cachep, NULL, flags);
 }
 EXPORT_SYMBOL(kmem_cache_alloc);
 
 void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
                gfp_t flags)
 {
     return __kmem_cache_alloc_lru(cachep, lru, flags);
 }
 EXPORT_SYMBOL(kmem_cache_alloc_lru);
 
 static __always_inline void
 cache_alloc_debugcheck_after_bulk(struct kmem_cache *s, gfp_t flags,
                   size_t size, void **p, unsigned long caller)
 {
     size_t i;
 
     for (i = 0; i < size; i++)
         p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller);
 }
 
 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
               void **p)
 {
     size_t i;
     struct obj_cgroup *objcg = NULL;
 
     s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags);
     if (!s)
         return 0;
 
     local_irq_disable();
     for (i = 0; i < size; i++) {
         void *objp = kfence_alloc(s, s->object_size, flags) ?: __do_cache_alloc(s, flags);
 
         if (unlikely(!objp))
             goto error;
         p[i] = objp;
     }
     local_irq_enable();
 
     cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_);
 
     /*
      * memcg and kmem_cache debug support and memory initialization.
      * Done outside of the IRQ disabled section.
      */
     slab_post_alloc_hook(s, objcg, flags, size, p,
                 slab_want_init_on_alloc(flags, s));
     /* FIXME: Trace call missing. Christoph would like a bulk variant */
     return size;
 error:
     local_irq_enable();
     cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
     slab_post_alloc_hook(s, objcg, flags, i, p, false);
     kmem_cache_free_bulk(s, i, p);
     return 0;
 }
 EXPORT_SYMBOL(kmem_cache_alloc_bulk);
 
 #ifdef CONFIG_TRACING
 void *
 kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
 {
     void *ret;
 
     ret = slab_alloc(cachep, NULL, flags, size, _RET_IP_);
 
     ret = kasan_kmalloc(cachep, ret, size, flags);
     trace_kmalloc(_RET_IP_, ret, cachep,
               size, cachep->size, flags);
     return ret;
 }
 EXPORT_SYMBOL(kmem_cache_alloc_trace);
 #endif
 
 #ifdef CONFIG_NUMA
 /**
  * kmem_cache_alloc_node - Allocate an object on the specified node
  * @cachep: The cache to allocate from.
  * @flags: See kmalloc().
  * @nodeid: node number of the target node.
  *
  * Identical to kmem_cache_alloc 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.
  *
  * Return: pointer to the new object or %NULL in case of error
  */
 void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
     void *ret = slab_alloc_node(cachep, flags, nodeid, cachep->object_size, _RET_IP_);
 
     trace_kmem_cache_alloc_node(_RET_IP_, ret, cachep,
                     cachep->object_size, cachep->size,
                     flags, nodeid);
 
     return ret;
 }
 EXPORT_SYMBOL(kmem_cache_alloc_node);
 
 #ifdef CONFIG_TRACING
 void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep,
                   gfp_t flags,
                   int nodeid,
                   size_t size)
 {
     void *ret;
 
     ret = slab_alloc_node(cachep, flags, nodeid, size, _RET_IP_);
 
     ret = kasan_kmalloc(cachep, ret, size, flags);
     trace_kmalloc_node(_RET_IP_, ret, cachep,
                size, cachep->size,
                flags, nodeid);
     return ret;
 }
 EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
 #endif
 
 static __always_inline void *
 __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
 {
     struct kmem_cache *cachep;
     void *ret;
 
     if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
         return NULL;
     cachep = kmalloc_slab(size, flags);
     if (unlikely(ZERO_OR_NULL_PTR(cachep)))
         return cachep;
     ret = kmem_cache_alloc_node_trace(cachep, flags, node, size);
     ret = kasan_kmalloc(cachep, ret, size, flags);
 
     return ret;
 }
 
 void *__kmalloc_node(size_t size, gfp_t flags, int node)
 {
     return __do_kmalloc_node(size, flags, node, _RET_IP_);
 }
 EXPORT_SYMBOL(__kmalloc_node);
 
 void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
         int node, unsigned long caller)
 {
     return __do_kmalloc_node(size, flags, node, caller);
 }
 EXPORT_SYMBOL(__kmalloc_node_track_caller);
 #endif /* CONFIG_NUMA */
 
 #ifdef CONFIG_PRINTK
 void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
 {
     struct kmem_cache *cachep;
     unsigned int objnr;
     void *objp;
 
     kpp->kp_ptr = object;
     kpp->kp_slab = slab;
     cachep = slab->slab_cache;
     kpp->kp_slab_cache = cachep;
     objp = object - obj_offset(cachep);
     kpp->kp_data_offset = obj_offset(cachep);
     slab = virt_to_slab(objp);
     objnr = obj_to_index(cachep, slab, objp);
     objp = index_to_obj(cachep, slab, objnr);
     kpp->kp_objp = objp;
     if (DEBUG && cachep->flags & SLAB_STORE_USER)
         kpp->kp_ret = *dbg_userword(cachep, objp);
 }
 #endif
 
 /**
  * __do_kmalloc - allocate memory
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kmalloc).
  * @caller: function caller for debug tracking of the caller
  *
  * Return: pointer to the allocated memory or %NULL in case of error
  */
 static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
                       unsigned long caller)
 {
     struct kmem_cache *cachep;
     void *ret;
 
     if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
         return NULL;
     cachep = kmalloc_slab(size, flags);
     if (unlikely(ZERO_OR_NULL_PTR(cachep)))
         return cachep;
     ret = slab_alloc(cachep, NULL, flags, size, caller);
 
     ret = kasan_kmalloc(cachep, ret, size, flags);
     trace_kmalloc(caller, ret, cachep,
               size, cachep->size, flags);
 
     return ret;
 }
 
 void *__kmalloc(size_t size, gfp_t flags)
 {
     return __do_kmalloc(size, flags, _RET_IP_);
 }
 EXPORT_SYMBOL(__kmalloc);
 
 void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
 {
     return __do_kmalloc(size, flags, caller);
 }
 EXPORT_SYMBOL(__kmalloc_track_caller);
 
 /**
  * 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;
     cachep = cache_from_obj(cachep, objp);
     if (!cachep)
         return;
 
     trace_kmem_cache_free(_RET_IP_, objp, cachep->name);
     local_irq_save(flags);
     debug_check_no_locks_freed(objp, cachep->object_size);
     if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
         debug_check_no_obj_freed(objp, cachep->object_size);
     __cache_free(cachep, objp, _RET_IP_);
     local_irq_restore(flags);
 }
 EXPORT_SYMBOL(kmem_cache_free);
 
 void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
 {
     struct kmem_cache *s;
     size_t i;
 
     local_irq_disable();
     for (i = 0; i < size; i++) {
         void *objp = p[i];
 
         if (!orig_s) /* called via kfree_bulk */
             s = virt_to_cache(objp);
         else
             s = cache_from_obj(orig_s, objp);
         if (!s)
             continue;
 
         debug_check_no_locks_freed(objp, s->object_size);
         if (!(s->flags & SLAB_DEBUG_OBJECTS))
             debug_check_no_obj_freed(objp, s->object_size);
 
         __cache_free(s, objp, _RET_IP_);
     }
     local_irq_enable();
 
     /* FIXME: add tracing */
 }
 EXPORT_SYMBOL(kmem_cache_free_bulk);
 
 /**
  * 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;
 
     trace_kfree(_RET_IP_, objp);
 
     if (unlikely(ZERO_OR_NULL_PTR(objp)))
         return;
     local_irq_save(flags);
     kfree_debugcheck(objp);
     c = virt_to_cache(objp);
     if (!c) {
         local_irq_restore(flags);
         return;
     }
     debug_check_no_locks_freed(objp, c->object_size);
 
     debug_check_no_obj_freed(objp, c->object_size);
     __cache_free(c, (void *)objp, _RET_IP_);
     local_irq_restore(flags);
 }
 EXPORT_SYMBOL(kfree);
 
 /*
  * This initializes kmem_cache_node or resizes various caches for all nodes.
  */
 static int setup_kmem_cache_nodes(struct kmem_cache *cachep, gfp_t gfp)
 {
     int ret;
     int node;
     struct kmem_cache_node *n;
 
     for_each_online_node(node) {
         ret = setup_kmem_cache_node(cachep, node, gfp, true);
         if (ret)
             goto fail;
 
     }
 
     return 0;
 
 fail:
     if (!cachep->list.next) {
         /* Cache is not active yet. Roll back what we did */
         node--;
         while (node >= 0) {
             n = get_node(cachep, node);
             if (n) {
                 kfree(n->shared);
                 free_alien_cache(n->alien);
                 kfree(n);
                 cachep->node[node] = NULL;
             }
             node--;
         }
     }
     return -ENOMEM;
 }
 
 /* Always called with the slab_mutex held */
 static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
                 int batchcount, int shared, gfp_t gfp)
 {
     struct array_cache __percpu *cpu_cache, *prev;
     int cpu;
 
     cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount);
     if (!cpu_cache)
         return -ENOMEM;
 
     prev = cachep->cpu_cache;
     cachep->cpu_cache = cpu_cache;
     /*
      * Without a previous cpu_cache there's no need to synchronize remote
      * cpus, so skip the IPIs.
      */
     if (prev)
         kick_all_cpus_sync();
 
     check_irq_on();
     cachep->batchcount = batchcount;
     cachep->limit = limit;
     cachep->shared = shared;
 
     if (!prev)
         goto setup_node;
 
     for_each_online_cpu(cpu) {
         LIST_HEAD(list);
         int node;
         struct kmem_cache_node *n;
         struct array_cache *ac = per_cpu_ptr(prev, cpu);
 
         node = cpu_to_mem(cpu);
         n = get_node(cachep, node);
         spin_lock_irq(&n->list_lock);
         free_block(cachep, ac->entry, ac->avail, node, &list);
         spin_unlock_irq(&n->list_lock);
         slabs_destroy(cachep, &list);
     }
     free_percpu(prev);
 
 setup_node:
     return setup_kmem_cache_nodes(cachep, gfp);
 }
 
 /* Called with slab_mutex held always */
 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
 {
     int err;
     int limit = 0;
     int shared = 0;
     int batchcount = 0;
 
     err = cache_random_seq_create(cachep, cachep->num, gfp);
     if (err)
         goto end;
 
     /*
      * 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->size > 131072)
         limit = 1;
     else if (cachep->size > PAGE_SIZE)
         limit = 8;
     else if (cachep->size > 1024)
         limit = 24;
     else if (cachep->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->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
     batchcount = (limit + 1) / 2;
     err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
 end:
     if (err)
         pr_err("enable_cpucache failed for %s, error %d\n",
                cachep->name, -err);
     return err;
 }
 
 /*
  * Drain an array if it contains any elements taking the node lock only if
  * necessary. Note that the node listlock also protects the array_cache
  * if drain_array() is used on the shared array.
  */
 static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
              struct array_cache *ac, int node)
 {
     LIST_HEAD(list);
 
     /* ac from n->shared can be freed if we don't hold the slab_mutex. */
     check_mutex_acquired();
 
     if (!ac || !ac->avail)
         return;
 
     if (ac->touched) {
         ac->touched = 0;
         return;
     }
 
     spin_lock_irq(&n->list_lock);
     drain_array_locked(cachep, ac, node, false, &list);
     spin_unlock_irq(&n->list_lock);
 
     slabs_destroy(cachep, &list);
 }
 
 /**
  * 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)
 {
     struct kmem_cache *searchp;
     struct kmem_cache_node *n;
     int node = numa_mem_id();
     struct delayed_work *work = to_delayed_work(w);
 
     if (!mutex_trylock(&slab_mutex))
         /* Give up. Setup the next iteration. */
         goto out;
 
     list_for_each_entry(searchp, &slab_caches, list) {
         check_irq_on();
 
         /*
          * We only take the node lock if absolutely necessary and we
          * have established with reasonable certainty that
          * we can do some work if the lock was obtained.
          */
         n = get_node(searchp, node);
 
         reap_alien(searchp, n);
 
         drain_array(searchp, n, cpu_cache_get(searchp), node);
 
         /*
          * These are racy checks but it does not matter
          * if we skip one check or scan twice.
          */
         if (time_after(n->next_reap, jiffies))
             goto next;
 
         n->next_reap = jiffies + REAPTIMEOUT_NODE;
 
         drain_array(searchp, n, n->shared, node);
 
         if (n->free_touched)
             n->free_touched = 0;
         else {
             int freed;
 
             freed = drain_freelist(searchp, n, (n->free_limit +
                 5 * searchp->num - 1) / (5 * searchp->num));
             STATS_ADD_REAPED(searchp, freed);
         }
 next:
         cond_resched();
     }
     check_irq_on();
     mutex_unlock(&slab_mutex);
     next_reap_node();
 out:
     /* Set up the next iteration */
     schedule_delayed_work_on(smp_processor_id(), work,
                 round_jiffies_relative(REAPTIMEOUT_AC));
 }
 
 void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
 {
     unsigned long active_objs, num_objs, active_slabs;
     unsigned long total_slabs = 0, free_objs = 0, shared_avail = 0;
     unsigned long free_slabs = 0;
     int node;
     struct kmem_cache_node *n;
 
     for_each_kmem_cache_node(cachep, node, n) {
         check_irq_on();
         spin_lock_irq(&n->list_lock);
 
         total_slabs += n->total_slabs;
         free_slabs += n->free_slabs;
         free_objs += n->free_objects;
 
         if (n->shared)
             shared_avail += n->shared->avail;
 
         spin_unlock_irq(&n->list_lock);
     }
     num_objs = total_slabs * cachep->num;
     active_slabs = total_slabs - free_slabs;
     active_objs = num_objs - free_objs;
 
     sinfo->active_objs = active_objs;
     sinfo->num_objs = num_objs;
     sinfo->active_slabs = active_slabs;
     sinfo->num_slabs = total_slabs;
     sinfo->shared_avail = shared_avail;
     sinfo->limit = cachep->limit;
     sinfo->batchcount = cachep->batchcount;
     sinfo->shared = cachep->shared;
     sinfo->objects_per_slab = cachep->num;
     sinfo->cache_order = cachep->gfporder;
 }
 
 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
 {
 #if STATS
     {           /* node 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
 }
 
 #define MAX_SLABINFO_WRITE 128
 /**
  * slabinfo_write - Tuning for the slab allocator
  * @file: unused
  * @buffer: user buffer
  * @count: data length
  * @ppos: unused
  *
  * Return: %0 on success, negative error code otherwise.
  */
 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(&slab_mutex);
     res = -EINVAL;
     list_for_each_entry(cachep, &slab_caches, list) {
         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,
                                GFP_KERNEL);
             }
             break;
         }
     }
     mutex_unlock(&slab_mutex);
     if (res >= 0)
         res = count;
     return res;
 }
 
 #ifdef CONFIG_HARDENED_USERCOPY
 /*
  * Rejects incorrectly sized objects and objects that are to be copied
  * to/from userspace but do not fall entirely within the containing slab
  * cache's usercopy region.
  *
  * Returns NULL if check passes, otherwise const char * to name of cache
  * to indicate an error.
  */
 void __check_heap_object(const void *ptr, unsigned long n,
              const struct slab *slab, bool to_user)
 {
     struct kmem_cache *cachep;
     unsigned int objnr;
     unsigned long offset;
 
     ptr = kasan_reset_tag(ptr);
 
     /* Find and validate object. */
     cachep = slab->slab_cache;
     objnr = obj_to_index(cachep, slab, (void *)ptr);
     BUG_ON(objnr >= cachep->num);
 
     /* Find offset within object. */
     if (is_kfence_address(ptr))
         offset = ptr - kfence_object_start(ptr);
     else
         offset = ptr - index_to_obj(cachep, slab, objnr) - obj_offset(cachep);
 
     /* Allow address range falling entirely within usercopy region. */
     if (offset >= cachep->useroffset &&
         offset - cachep->useroffset <= cachep->usersize &&
         n <= cachep->useroffset - offset + cachep->usersize)
         return;
 
     usercopy_abort("SLAB object", cachep->name, to_user, offset, n);
 }
 #endif /* CONFIG_HARDENED_USERCOPY */
 
 /**
  * __ksize -- Uninstrumented ksize.
  * @objp: pointer to the object
  *
  * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same
  * safety checks as ksize() with KASAN instrumentation enabled.
  *
  * Return: size of the actual memory used by @objp in bytes
  */
 size_t __ksize(const void *objp)
 {
     struct kmem_cache *c;
     size_t size;
 
     BUG_ON(!objp);
     if (unlikely(objp == ZERO_SIZE_PTR))
         return 0;
 
     c = virt_to_cache(objp);
     size = c ? c->object_size : 0;
 
     return size;
 }
 EXPORT_SYMBOL(__ksize);