/*
   * Slab allocator functions that are independent of the allocator strategy
   *
   * (C) 2012 Christoph Lameter <cl@linux.com>
   */
  #include <linux/slab.h>
  
  #include <linux/mm.h>
  #include <linux/poison.h>
  #include <linux/interrupt.h>
  #include <linux/memory.h>
  #include <linux/compiler.h>
  #include <linux/module.h>

  #include <linux/cpu.h>
  #include <linux/uaccess.h>

  #include <linux/seq_file.h>
  #include <linux/proc_fs.h>

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

  #include <linux/memcontrol.h>

  
  #define CREATE_TRACE_POINTS

  #include <trace/events/kmem.h>

  #include "slab.h"
  
  enum slab_state slab_state;

  LIST_HEAD(slab_caches);
  DEFINE_MUTEX(slab_mutex);

  struct kmem_cache *kmem_cache;

  /*

   * Set of flags that will prevent slab merging
   */
  #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
  		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \

  		SLAB_FAILSLAB | SLAB_KASAN)

  #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
  			 SLAB_NOTRACK | SLAB_ACCOUNT)

  
  /*
   * Merge control. If this is set then no merging of slab caches will occur.
   * (Could be removed. This was introduced to pacify the merge skeptics.)
   */
  static int slab_nomerge;
  
  static int __init setup_slab_nomerge(char *str)
  {
  	slab_nomerge = 1;
  	return 1;
  }
  
  #ifdef CONFIG_SLUB
  __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
  #endif
  
  __setup("slab_nomerge", setup_slab_nomerge);
  
  /*

   * Determine the size of a slab object
   */
  unsigned int kmem_cache_size(struct kmem_cache *s)
  {
  	return s->object_size;
  }
  EXPORT_SYMBOL(kmem_cache_size);

  #ifdef CONFIG_DEBUG_VM

  static int kmem_cache_sanity_check(const char *name, size_t size)

  {
  	struct kmem_cache *s = NULL;

  	if (!name || in_interrupt() || size < sizeof(void *) ||
  		size > KMALLOC_MAX_SIZE) {

  		pr_err("kmem_cache_create(%s) integrity check failed
  ", name);
  		return -EINVAL;

  	}

  	list_for_each_entry(s, &slab_caches, list) {
  		char tmp;
  		int res;
  
  		/*
  		 * This happens when the module gets unloaded and doesn't
  		 * destroy its slab cache and no-one else reuses the vmalloc
  		 * area of the module.  Print a warning.
  		 */
  		res = probe_kernel_address(s->name, tmp);
  		if (res) {

  			pr_err("Slab cache with size %d has lost its name
  ",

  			       s->object_size);
  			continue;
  		}

  	}
  
  	WARN_ON(strchr(name, ' '));	/* It confuses parsers */

  	return 0;
  }
  #else

  static inline int kmem_cache_sanity_check(const char *name, size_t size)

  {
  	return 0;
  }

  #endif

  void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
  {
  	size_t i;

  	for (i = 0; i < nr; i++) {
  		if (s)
  			kmem_cache_free(s, p[i]);
  		else
  			kfree(p[i]);
  	}

  }

  int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,

  								void **p)
  {
  	size_t i;
  
  	for (i = 0; i < nr; i++) {
  		void *x = p[i] = kmem_cache_alloc(s, flags);
  		if (!x) {
  			__kmem_cache_free_bulk(s, i, p);

  			return 0;

  		}
  	}

  	return i;

  }

  #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)

  void slab_init_memcg_params(struct kmem_cache *s)

  {

  	s->memcg_params.is_root_cache = true;

  	INIT_LIST_HEAD(&s->memcg_params.list);

  	RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
  }
  
  static int init_memcg_params(struct kmem_cache *s,
  		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
  {
  	struct memcg_cache_array *arr;

  	if (memcg) {
  		s->memcg_params.is_root_cache = false;
  		s->memcg_params.memcg = memcg;
  		s->memcg_params.root_cache = root_cache;

  		return 0;

  	}

  	slab_init_memcg_params(s);

  	if (!memcg_nr_cache_ids)
  		return 0;

  	arr = kzalloc(sizeof(struct memcg_cache_array) +
  		      memcg_nr_cache_ids * sizeof(void *),
  		      GFP_KERNEL);
  	if (!arr)
  		return -ENOMEM;

  	RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);

  	return 0;
  }

  static void destroy_memcg_params(struct kmem_cache *s)

  {

  	if (is_root_cache(s))
  		kfree(rcu_access_pointer(s->memcg_params.memcg_caches));

  }

  static int update_memcg_params(struct kmem_cache *s, int new_array_size)

  {

  	struct memcg_cache_array *old, *new;

  	if (!is_root_cache(s))
  		return 0;

  	new = kzalloc(sizeof(struct memcg_cache_array) +
  		      new_array_size * sizeof(void *), GFP_KERNEL);
  	if (!new)

  		return -ENOMEM;

  	old = rcu_dereference_protected(s->memcg_params.memcg_caches,
  					lockdep_is_held(&slab_mutex));
  	if (old)
  		memcpy(new->entries, old->entries,
  		       memcg_nr_cache_ids * sizeof(void *));

  	rcu_assign_pointer(s->memcg_params.memcg_caches, new);
  	if (old)
  		kfree_rcu(old, rcu);

  	return 0;
  }

  int memcg_update_all_caches(int num_memcgs)
  {
  	struct kmem_cache *s;
  	int ret = 0;

  	mutex_lock(&slab_mutex);

  	list_for_each_entry(s, &slab_caches, list) {

  		ret = update_memcg_params(s, num_memcgs);

  		/*

  		 * Instead of freeing the memory, we'll just leave the caches
  		 * up to this point in an updated state.
  		 */
  		if (ret)

  			break;

  	}

  	mutex_unlock(&slab_mutex);
  	return ret;
  }

  #else

  static inline int init_memcg_params(struct kmem_cache *s,
  		struct mem_cgroup *memcg, struct kmem_cache *root_cache)

  {
  	return 0;
  }

  static inline void destroy_memcg_params(struct kmem_cache *s)

  {
  }

  #endif /* CONFIG_MEMCG && !CONFIG_SLOB */

  /*

   * Find a mergeable slab cache
   */
  int slab_unmergeable(struct kmem_cache *s)
  {
  	if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
  		return 1;
  
  	if (!is_root_cache(s))
  		return 1;
  
  	if (s->ctor)
  		return 1;
  
  	/*
  	 * We may have set a slab to be unmergeable during bootstrap.
  	 */
  	if (s->refcount < 0)
  		return 1;
  
  	return 0;
  }
  
  struct kmem_cache *find_mergeable(size_t size, size_t align,
  		unsigned long flags, const char *name, void (*ctor)(void *))
  {
  	struct kmem_cache *s;
  
  	if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
  		return NULL;
  
  	if (ctor)
  		return NULL;
  
  	size = ALIGN(size, sizeof(void *));
  	align = calculate_alignment(flags, align, size);
  	size = ALIGN(size, align);
  	flags = kmem_cache_flags(size, flags, name, NULL);

  	list_for_each_entry_reverse(s, &slab_caches, list) {

  		if (slab_unmergeable(s))
  			continue;
  
  		if (size > s->size)
  			continue;
  
  		if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
  			continue;
  		/*
  		 * Check if alignment is compatible.
  		 * Courtesy of Adrian Drzewiecki
  		 */
  		if ((s->size & ~(align - 1)) != s->size)
  			continue;
  
  		if (s->size - size >= sizeof(void *))
  			continue;

  		if (IS_ENABLED(CONFIG_SLAB) && align &&
  			(align > s->align || s->align % align))
  			continue;

  		return s;
  	}
  	return NULL;
  }
  
  /*

   * Figure out what the alignment of the objects will be given a set of
   * flags, a user specified alignment and the size of the objects.
   */
  unsigned long calculate_alignment(unsigned long flags,
  		unsigned long align, unsigned long size)
  {
  	/*
  	 * If the user wants hardware cache aligned objects then follow that
  	 * suggestion if the object is sufficiently large.
  	 *
  	 * The hardware cache alignment cannot override the specified
  	 * alignment though. If that is greater then use it.
  	 */
  	if (flags & SLAB_HWCACHE_ALIGN) {
  		unsigned long ralign = cache_line_size();
  		while (size <= ralign / 2)
  			ralign /= 2;
  		align = max(align, ralign);
  	}
  
  	if (align < ARCH_SLAB_MINALIGN)
  		align = ARCH_SLAB_MINALIGN;
  
  	return ALIGN(align, sizeof(void *));
  }

  static struct kmem_cache *create_cache(const char *name,
  		size_t object_size, size_t size, size_t align,
  		unsigned long flags, void (*ctor)(void *),
  		struct mem_cgroup *memcg, struct kmem_cache *root_cache)

  {
  	struct kmem_cache *s;
  	int err;
  
  	err = -ENOMEM;
  	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
  	if (!s)
  		goto out;
  
  	s->name = name;
  	s->object_size = object_size;
  	s->size = size;
  	s->align = align;
  	s->ctor = ctor;

  	err = init_memcg_params(s, memcg, root_cache);

  	if (err)
  		goto out_free_cache;
  
  	err = __kmem_cache_create(s, flags);
  	if (err)
  		goto out_free_cache;
  
  	s->refcount = 1;
  	list_add(&s->list, &slab_caches);

  out:
  	if (err)
  		return ERR_PTR(err);
  	return s;
  
  out_free_cache:

  	destroy_memcg_params(s);

  	kmem_cache_free(kmem_cache, s);

  	goto out;
  }

  
  /*

   * kmem_cache_create - Create a cache.
   * @name: A string which is used in /proc/slabinfo to identify this cache.
   * @size: The size of objects to be created in this cache.
   * @align: The required alignment for the objects.
   * @flags: SLAB flags
   * @ctor: A constructor for the objects.
   *
   * Returns a ptr to the cache on success, NULL on failure.
   * Cannot be called within a interrupt, 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.
   */

  struct kmem_cache *

  kmem_cache_create(const char *name, size_t size, size_t align,
  		  unsigned long flags, void (*ctor)(void *))

  {

  	struct kmem_cache *s = NULL;

  	const char *cache_name;

  	int err;

  	get_online_cpus();

  	get_online_mems();

  	memcg_get_cache_ids();

  	mutex_lock(&slab_mutex);

  	err = kmem_cache_sanity_check(name, size);

  	if (err) {

  		goto out_unlock;

  	}

  	/*
  	 * Some allocators will constraint the set of valid flags to a subset
  	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
  	 * case, and we'll just provide them with a sanitized version of the
  	 * passed flags.
  	 */
  	flags &= CACHE_CREATE_MASK;

  	s = __kmem_cache_alias(name, size, align, flags, ctor);
  	if (s)

  		goto out_unlock;

  	cache_name = kstrdup_const(name, GFP_KERNEL);

  	if (!cache_name) {
  		err = -ENOMEM;
  		goto out_unlock;
  	}

  	s = create_cache(cache_name, size, size,
  			 calculate_alignment(flags, align, size),
  			 flags, ctor, NULL, NULL);

  	if (IS_ERR(s)) {
  		err = PTR_ERR(s);

  		kfree_const(cache_name);

  	}

  
  out_unlock:

  	mutex_unlock(&slab_mutex);

  	memcg_put_cache_ids();

  	put_online_mems();

  	put_online_cpus();

  	if (err) {

  		if (flags & SLAB_PANIC)
  			panic("kmem_cache_create: Failed to create slab '%s'. Error %d
  ",
  				name, err);
  		else {

  			pr_warn("kmem_cache_create(%s) failed with error %d
  ",

  				name, err);
  			dump_stack();
  		}

  		return NULL;
  	}

  	return s;
  }

  EXPORT_SYMBOL(kmem_cache_create);

  static int shutdown_cache(struct kmem_cache *s,

  		struct list_head *release, bool *need_rcu_barrier)
  {

  	if (__kmem_cache_shutdown(s) != 0)

  		return -EBUSY;

  
  	if (s->flags & SLAB_DESTROY_BY_RCU)
  		*need_rcu_barrier = true;

  	list_move(&s->list, release);
  	return 0;
  }

  static void release_caches(struct list_head *release, bool need_rcu_barrier)

  {
  	struct kmem_cache *s, *s2;
  
  	if (need_rcu_barrier)
  		rcu_barrier();
  
  	list_for_each_entry_safe(s, s2, release, list) {
  #ifdef SLAB_SUPPORTS_SYSFS
  		sysfs_slab_remove(s);
  #else
  		slab_kmem_cache_release(s);
  #endif
  	}
  }

  #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)

  /*

   * memcg_create_kmem_cache - Create a cache for a memory cgroup.

   * @memcg: The memory cgroup the new cache is for.
   * @root_cache: The parent of the new cache.
   *
   * This function attempts to create a kmem cache that will serve allocation
   * requests going from @memcg to @root_cache. The new cache inherits properties
   * from its parent.
   */

  void memcg_create_kmem_cache(struct mem_cgroup *memcg,
  			     struct kmem_cache *root_cache)

  {

  	static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */

  	struct cgroup_subsys_state *css = &memcg->css;

  	struct memcg_cache_array *arr;

  	struct kmem_cache *s = NULL;

  	char *cache_name;

  	int idx;

  
  	get_online_cpus();

  	get_online_mems();

  	mutex_lock(&slab_mutex);

  	/*

  	 * The memory cgroup could have been offlined while the cache

  	 * creation work was pending.
  	 */

  	if (memcg->kmem_state != KMEM_ONLINE)

  		goto out_unlock;

  	idx = memcg_cache_id(memcg);
  	arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
  					lockdep_is_held(&slab_mutex));

  	/*
  	 * Since per-memcg caches are created asynchronously on first
  	 * allocation (see memcg_kmem_get_cache()), several threads can try to
  	 * create the same cache, but only one of them may succeed.
  	 */

  	if (arr->entries[idx])

  		goto out_unlock;

  	cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));

  	cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
  			       css->serial_nr, memcg_name_buf);

  	if (!cache_name)
  		goto out_unlock;

  	s = create_cache(cache_name, root_cache->object_size,
  			 root_cache->size, root_cache->align,

  			 root_cache->flags & CACHE_CREATE_MASK,
  			 root_cache->ctor, memcg, root_cache);

  	/*
  	 * If we could not create a memcg cache, do not complain, because
  	 * that's not critical at all as we can always proceed with the root
  	 * cache.
  	 */

  	if (IS_ERR(s)) {

  		kfree(cache_name);

  		goto out_unlock;

  	}

  	list_add(&s->memcg_params.list, &root_cache->memcg_params.list);

  	/*
  	 * Since readers won't lock (see cache_from_memcg_idx()), we need a
  	 * barrier here to ensure nobody will see the kmem_cache partially
  	 * initialized.
  	 */
  	smp_wmb();

  	arr->entries[idx] = s;

  out_unlock:
  	mutex_unlock(&slab_mutex);

  
  	put_online_mems();

  	put_online_cpus();

  }

  void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
  {
  	int idx;
  	struct memcg_cache_array *arr;

  	struct kmem_cache *s, *c;

  
  	idx = memcg_cache_id(memcg);

  	get_online_cpus();
  	get_online_mems();

  	mutex_lock(&slab_mutex);
  	list_for_each_entry(s, &slab_caches, list) {
  		if (!is_root_cache(s))
  			continue;
  
  		arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
  						lockdep_is_held(&slab_mutex));

  		c = arr->entries[idx];
  		if (!c)
  			continue;
  
  		__kmem_cache_shrink(c, true);

  		arr->entries[idx] = NULL;
  	}
  	mutex_unlock(&slab_mutex);

  
  	put_online_mems();
  	put_online_cpus();

  }

  static int __shutdown_memcg_cache(struct kmem_cache *s,
  		struct list_head *release, bool *need_rcu_barrier)
  {
  	BUG_ON(is_root_cache(s));
  
  	if (shutdown_cache(s, release, need_rcu_barrier))
  		return -EBUSY;
  
  	list_del(&s->memcg_params.list);
  	return 0;
  }

  void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)

  {

  	LIST_HEAD(release);
  	bool need_rcu_barrier = false;
  	struct kmem_cache *s, *s2;

  	get_online_cpus();
  	get_online_mems();

  	mutex_lock(&slab_mutex);

  	list_for_each_entry_safe(s, s2, &slab_caches, list) {

  		if (is_root_cache(s) || s->memcg_params.memcg != memcg)

  			continue;
  		/*
  		 * The cgroup is about to be freed and therefore has no charges
  		 * left. Hence, all its caches must be empty by now.
  		 */

  		BUG_ON(__shutdown_memcg_cache(s, &release, &need_rcu_barrier));

  	}
  	mutex_unlock(&slab_mutex);

  	put_online_mems();
  	put_online_cpus();

  	release_caches(&release, need_rcu_barrier);

  }

  
  static int shutdown_memcg_caches(struct kmem_cache *s,
  		struct list_head *release, bool *need_rcu_barrier)
  {
  	struct memcg_cache_array *arr;
  	struct kmem_cache *c, *c2;
  	LIST_HEAD(busy);
  	int i;
  
  	BUG_ON(!is_root_cache(s));
  
  	/*
  	 * First, shutdown active caches, i.e. caches that belong to online
  	 * memory cgroups.
  	 */
  	arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
  					lockdep_is_held(&slab_mutex));
  	for_each_memcg_cache_index(i) {
  		c = arr->entries[i];
  		if (!c)
  			continue;
  		if (__shutdown_memcg_cache(c, release, need_rcu_barrier))
  			/*
  			 * The cache still has objects. Move it to a temporary
  			 * list so as not to try to destroy it for a second
  			 * time while iterating over inactive caches below.
  			 */
  			list_move(&c->memcg_params.list, &busy);
  		else
  			/*
  			 * The cache is empty and will be destroyed soon. Clear
  			 * the pointer to it in the memcg_caches array so that
  			 * it will never be accessed even if the root cache
  			 * stays alive.
  			 */
  			arr->entries[i] = NULL;
  	}
  
  	/*
  	 * Second, shutdown all caches left from memory cgroups that are now
  	 * offline.
  	 */
  	list_for_each_entry_safe(c, c2, &s->memcg_params.list,
  				 memcg_params.list)
  		__shutdown_memcg_cache(c, release, need_rcu_barrier);
  
  	list_splice(&busy, &s->memcg_params.list);
  
  	/*
  	 * A cache being destroyed must be empty. In particular, this means
  	 * that all per memcg caches attached to it must be empty too.
  	 */
  	if (!list_empty(&s->memcg_params.list))
  		return -EBUSY;
  	return 0;
  }
  #else
  static inline int shutdown_memcg_caches(struct kmem_cache *s,
  		struct list_head *release, bool *need_rcu_barrier)
  {
  	return 0;
  }

  #endif /* CONFIG_MEMCG && !CONFIG_SLOB */

  void slab_kmem_cache_release(struct kmem_cache *s)
  {

  	__kmem_cache_release(s);

  	destroy_memcg_params(s);

  	kfree_const(s->name);

  	kmem_cache_free(kmem_cache, s);
  }

  void kmem_cache_destroy(struct kmem_cache *s)
  {

  	LIST_HEAD(release);
  	bool need_rcu_barrier = false;

  	int err;

  	if (unlikely(!s))
  		return;

  	get_online_cpus();

  	get_online_mems();

  	kasan_cache_destroy(s);

  	mutex_lock(&slab_mutex);

  	s->refcount--;

  	if (s->refcount)
  		goto out_unlock;

  	err = shutdown_memcg_caches(s, &release, &need_rcu_barrier);
  	if (!err)

  		err = shutdown_cache(s, &release, &need_rcu_barrier);

  	if (err) {

  		pr_err("kmem_cache_destroy %s: Slab cache still has objects
  ",
  		       s->name);

  		dump_stack();
  	}

  out_unlock:
  	mutex_unlock(&slab_mutex);

  	put_online_mems();

  	put_online_cpus();

  	release_caches(&release, need_rcu_barrier);

  }
  EXPORT_SYMBOL(kmem_cache_destroy);

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

  	kasan_cache_shrink(cachep);

  	ret = __kmem_cache_shrink(cachep, false);

  	put_online_mems();
  	put_online_cpus();
  	return ret;
  }
  EXPORT_SYMBOL(kmem_cache_shrink);

  bool slab_is_available(void)

  {
  	return slab_state >= UP;
  }

  #ifndef CONFIG_SLOB
  /* Create a cache during boot when no slab services are available yet */
  void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
  		unsigned long flags)
  {
  	int err;
  
  	s->name = name;
  	s->size = s->object_size = size;

  	s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);

  
  	slab_init_memcg_params(s);

  	err = __kmem_cache_create(s, flags);
  
  	if (err)

  		panic("Creation of kmalloc slab %s size=%zu failed. Reason %d
  ",

  					name, size, err);
  
  	s->refcount = -1;	/* Exempt from merging for now */
  }
  
  struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
  				unsigned long flags)
  {
  	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
  
  	if (!s)
  		panic("Out of memory when creating slab %s
  ", name);
  
  	create_boot_cache(s, name, size, flags);
  	list_add(&s->list, &slab_caches);
  	s->refcount = 1;
  	return s;
  }

  struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
  EXPORT_SYMBOL(kmalloc_caches);
  
  #ifdef CONFIG_ZONE_DMA
  struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
  EXPORT_SYMBOL(kmalloc_dma_caches);
  #endif

  /*

   * Conversion table for small slabs sizes / 8 to the index in the
   * kmalloc array. This is necessary for slabs < 192 since we have non power
   * of two cache sizes there. The size of larger slabs can be determined using
   * fls.
   */
  static s8 size_index[24] = {
  	3,	/* 8 */
  	4,	/* 16 */
  	5,	/* 24 */
  	5,	/* 32 */
  	6,	/* 40 */
  	6,	/* 48 */
  	6,	/* 56 */
  	6,	/* 64 */
  	1,	/* 72 */
  	1,	/* 80 */
  	1,	/* 88 */
  	1,	/* 96 */
  	7,	/* 104 */
  	7,	/* 112 */
  	7,	/* 120 */
  	7,	/* 128 */
  	2,	/* 136 */
  	2,	/* 144 */
  	2,	/* 152 */
  	2,	/* 160 */
  	2,	/* 168 */
  	2,	/* 176 */
  	2,	/* 184 */
  	2	/* 192 */
  };
  
  static inline int size_index_elem(size_t bytes)
  {
  	return (bytes - 1) / 8;
  }
  
  /*
   * Find the kmem_cache structure that serves a given size of
   * allocation
   */
  struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
  {
  	int index;

  	if (unlikely(size > KMALLOC_MAX_SIZE)) {

  		WARN_ON_ONCE(!(flags & __GFP_NOWARN));

  		return NULL;

  	}

  	if (size <= 192) {
  		if (!size)
  			return ZERO_SIZE_PTR;
  
  		index = size_index[size_index_elem(size)];
  	} else
  		index = fls(size - 1);
  
  #ifdef CONFIG_ZONE_DMA

  	if (unlikely((flags & GFP_DMA)))

  		return kmalloc_dma_caches[index];
  
  #endif
  	return kmalloc_caches[index];
  }
  
  /*

   * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
   * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
   * kmalloc-67108864.
   */
  static struct {
  	const char *name;
  	unsigned long size;
  } const kmalloc_info[] __initconst = {
  	{NULL,                      0},		{"kmalloc-96",             96},
  	{"kmalloc-192",           192},		{"kmalloc-8",               8},
  	{"kmalloc-16",             16},		{"kmalloc-32",             32},
  	{"kmalloc-64",             64},		{"kmalloc-128",           128},
  	{"kmalloc-256",           256},		{"kmalloc-512",           512},
  	{"kmalloc-1024",         1024},		{"kmalloc-2048",         2048},
  	{"kmalloc-4096",         4096},		{"kmalloc-8192",         8192},
  	{"kmalloc-16384",       16384},		{"kmalloc-32768",       32768},
  	{"kmalloc-65536",       65536},		{"kmalloc-131072",     131072},
  	{"kmalloc-262144",     262144},		{"kmalloc-524288",     524288},
  	{"kmalloc-1048576",   1048576},		{"kmalloc-2097152",   2097152},
  	{"kmalloc-4194304",   4194304},		{"kmalloc-8388608",   8388608},
  	{"kmalloc-16777216", 16777216},		{"kmalloc-33554432", 33554432},
  	{"kmalloc-67108864", 67108864}
  };
  
  /*

   * Patch up the size_index table if we have strange large alignment
   * requirements for the kmalloc array. This is only the case for
   * MIPS it seems. The standard arches will not generate any code here.
   *
   * Largest permitted alignment is 256 bytes due to the way we
   * handle the index determination for the smaller caches.
   *
   * Make sure that nothing crazy happens if someone starts tinkering
   * around with ARCH_KMALLOC_MINALIGN

   */

  void __init setup_kmalloc_cache_index_table(void)

  {
  	int i;

  	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
  		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
  
  	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
  		int elem = size_index_elem(i);
  
  		if (elem >= ARRAY_SIZE(size_index))
  			break;
  		size_index[elem] = KMALLOC_SHIFT_LOW;
  	}
  
  	if (KMALLOC_MIN_SIZE >= 64) {
  		/*
  		 * The 96 byte size cache is not used if the alignment
  		 * is 64 byte.
  		 */
  		for (i = 64 + 8; i <= 96; i += 8)
  			size_index[size_index_elem(i)] = 7;
  
  	}
  
  	if (KMALLOC_MIN_SIZE >= 128) {
  		/*
  		 * The 192 byte sized cache is not used if the alignment
  		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
  		 * instead.
  		 */
  		for (i = 128 + 8; i <= 192; i += 8)
  			size_index[size_index_elem(i)] = 8;
  	}

  }

  static void __init new_kmalloc_cache(int idx, unsigned long flags)

  {
  	kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
  					kmalloc_info[idx].size, flags);
  }

  /*
   * Create the kmalloc array. Some of the regular kmalloc arrays
   * may already have been created because they were needed to
   * enable allocations for slab creation.
   */
  void __init create_kmalloc_caches(unsigned long flags)
  {
  	int i;

  	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
  		if (!kmalloc_caches[i])
  			new_kmalloc_cache(i, flags);

  		/*

  		 * Caches that are not of the two-to-the-power-of size.
  		 * These have to be created immediately after the
  		 * earlier power of two caches

  		 */

  		if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
  			new_kmalloc_cache(1, flags);
  		if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
  			new_kmalloc_cache(2, flags);

  	}

  	/* Kmalloc array is now usable */
  	slab_state = UP;

  #ifdef CONFIG_ZONE_DMA
  	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
  		struct kmem_cache *s = kmalloc_caches[i];
  
  		if (s) {
  			int size = kmalloc_size(i);
  			char *n = kasprintf(GFP_NOWAIT,
  				 "dma-kmalloc-%d", size);
  
  			BUG_ON(!n);
  			kmalloc_dma_caches[i] = create_kmalloc_cache(n,
  				size, SLAB_CACHE_DMA | flags);
  		}
  	}
  #endif
  }

  #endif /* !CONFIG_SLOB */

  /*
   * To avoid unnecessary overhead, we pass through large allocation requests
   * directly to the page allocator. We use __GFP_COMP, because we will need to
   * know the allocation order to free the pages properly in kfree.
   */

  void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
  {
  	void *ret;
  	struct page *page;
  
  	flags |= __GFP_COMP;

  	page = alloc_pages(flags, order);

  	ret = page ? page_address(page) : NULL;
  	kmemleak_alloc(ret, size, 1, flags);

  	kasan_kmalloc_large(ret, size, flags);

  	return ret;
  }
  EXPORT_SYMBOL(kmalloc_order);

  #ifdef CONFIG_TRACING
  void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
  {
  	void *ret = kmalloc_order(size, flags, order);
  	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
  	return ret;
  }
  EXPORT_SYMBOL(kmalloc_order_trace);
  #endif

  #ifdef CONFIG_SLAB_FREELIST_RANDOM
  /* Randomize a generic freelist */
  static void freelist_randomize(struct rnd_state *state, unsigned int *list,
  			size_t count)
  {
  	size_t i;
  	unsigned int rand;
  
  	for (i = 0; i < count; i++)
  		list[i] = i;
  
  	/* Fisher-Yates shuffle */
  	for (i = count - 1; i > 0; i--) {
  		rand = prandom_u32_state(state);
  		rand %= (i + 1);
  		swap(list[i], list[rand]);
  	}
  }
  
  /* Create a random sequence per cache */
  int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
  				    gfp_t gfp)
  {
  	struct rnd_state state;
  
  	if (count < 2 || cachep->random_seq)
  		return 0;
  
  	cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
  	if (!cachep->random_seq)
  		return -ENOMEM;
  
  	/* Get best entropy at this stage of boot */
  	prandom_seed_state(&state, get_random_long());
  
  	freelist_randomize(&state, cachep->random_seq, count);
  	return 0;
  }
  
  /* Destroy the per-cache random freelist sequence */
  void cache_random_seq_destroy(struct kmem_cache *cachep)
  {
  	kfree(cachep->random_seq);
  	cachep->random_seq = NULL;
  }
  #endif /* CONFIG_SLAB_FREELIST_RANDOM */

  #ifdef CONFIG_SLABINFO

  
  #ifdef CONFIG_SLAB
  #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
  #else
  #define SLABINFO_RIGHTS S_IRUSR
  #endif

  static void print_slabinfo_header(struct seq_file *m)

  {
  	/*
  	 * Output format version, so at least we can change it
  	 * without _too_ many complaints.
  	 */
  #ifdef CONFIG_DEBUG_SLAB
  	seq_puts(m, "slabinfo - version: 2.1 (statistics)
  ");
  #else
  	seq_puts(m, "slabinfo - version: 2.1
  ");
  #endif

  	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");

  	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
  	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
  #ifdef CONFIG_DEBUG_SLAB

  	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");

  	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
  #endif
  	seq_putc(m, '
  ');
  }

  void *slab_start(struct seq_file *m, loff_t *pos)

  {

  	mutex_lock(&slab_mutex);

  	return seq_list_start(&slab_caches, *pos);
  }

  void *slab_next(struct seq_file *m, void *p, loff_t *pos)

  {
  	return seq_list_next(p, &slab_caches, pos);
  }

  void slab_stop(struct seq_file *m, void *p)

  {
  	mutex_unlock(&slab_mutex);
  }

  static void
  memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
  {
  	struct kmem_cache *c;
  	struct slabinfo sinfo;

  
  	if (!is_root_cache(s))
  		return;

  	for_each_memcg_cache(c, s) {

  		memset(&sinfo, 0, sizeof(sinfo));
  		get_slabinfo(c, &sinfo);
  
  		info->active_slabs += sinfo.active_slabs;
  		info->num_slabs += sinfo.num_slabs;
  		info->shared_avail += sinfo.shared_avail;
  		info->active_objs += sinfo.active_objs;
  		info->num_objs += sinfo.num_objs;
  	}
  }

  static void cache_show(struct kmem_cache *s, struct seq_file *m)

  {

  	struct slabinfo sinfo;
  
  	memset(&sinfo, 0, sizeof(sinfo));
  	get_slabinfo(s, &sinfo);

  	memcg_accumulate_slabinfo(s, &sinfo);

  	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",

  		   cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,

  		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
  
  	seq_printf(m, " : tunables %4u %4u %4u",
  		   sinfo.limit, sinfo.batchcount, sinfo.shared);
  	seq_printf(m, " : slabdata %6lu %6lu %6lu",
  		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
  	slabinfo_show_stats(m, s);
  	seq_putc(m, '
  ');

  }

  static int slab_show(struct seq_file *m, void *p)

  {
  	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);

  	if (p == slab_caches.next)
  		print_slabinfo_header(m);

  	if (is_root_cache(s))
  		cache_show(s, m);
  	return 0;
  }

  #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)

  int memcg_slab_show(struct seq_file *m, void *p)
  {
  	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
  	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
  
  	if (p == slab_caches.next)
  		print_slabinfo_header(m);

  	if (!is_root_cache(s) && s->memcg_params.memcg == memcg)

  		cache_show(s, m);
  	return 0;

  }

  #endif

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

  	.start = slab_start,

  	.next = slab_next,
  	.stop = slab_stop,

  	.show = slab_show,

  };
  
  static int slabinfo_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &slabinfo_op);
  }
  
  static const struct file_operations proc_slabinfo_operations = {
  	.open		= slabinfo_open,
  	.read		= seq_read,
  	.write          = slabinfo_write,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };
  
  static int __init slab_proc_init(void)
  {

  	proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
  						&proc_slabinfo_operations);

  	return 0;
  }
  module_init(slab_proc_init);
  #endif /* CONFIG_SLABINFO */

  
  static __always_inline void *__do_krealloc(const void *p, size_t new_size,
  					   gfp_t flags)
  {
  	void *ret;
  	size_t ks = 0;
  
  	if (p)
  		ks = ksize(p);

  	if (ks >= new_size) {

  		kasan_krealloc((void *)p, new_size, flags);

  		return (void *)p;

  	}

  
  	ret = kmalloc_track_caller(new_size, flags);
  	if (ret && p)
  		memcpy(ret, p, ks);
  
  	return ret;
  }
  
  /**
   * __krealloc - like krealloc() but don't free @p.
   * @p: object to reallocate memory for.
   * @new_size: how many bytes of memory are required.
   * @flags: the type of memory to allocate.
   *
   * This function is like krealloc() except it never frees the originally
   * allocated buffer. Use this if you don't want to free the buffer immediately
   * like, for example, with RCU.
   */
  void *__krealloc(const void *p, size_t new_size, gfp_t flags)
  {
  	if (unlikely(!new_size))
  		return ZERO_SIZE_PTR;
  
  	return __do_krealloc(p, new_size, flags);
  
  }
  EXPORT_SYMBOL(__krealloc);
  
  /**
   * krealloc - reallocate memory. The contents will remain unchanged.
   * @p: object to reallocate memory for.
   * @new_size: how many bytes of memory are required.
   * @flags: the type of memory to allocate.
   *
   * The contents of the object pointed to are preserved up to the
   * lesser of the new and old sizes.  If @p is %NULL, krealloc()
   * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
   * %NULL pointer, the object pointed to is freed.
   */
  void *krealloc(const void *p, size_t new_size, gfp_t flags)
  {
  	void *ret;
  
  	if (unlikely(!new_size)) {
  		kfree(p);
  		return ZERO_SIZE_PTR;
  	}
  
  	ret = __do_krealloc(p, new_size, flags);
  	if (ret && p != ret)
  		kfree(p);
  
  	return ret;
  }
  EXPORT_SYMBOL(krealloc);
  
  /**
   * kzfree - like kfree but zero memory
   * @p: object to free memory of
   *
   * The memory of the object @p points to is zeroed before freed.
   * If @p is %NULL, kzfree() does nothing.
   *
   * Note: this function zeroes the whole allocated buffer which can be a good
   * deal bigger than the requested buffer size passed to kmalloc(). So be
   * careful when using this function in performance sensitive code.
   */
  void kzfree(const void *p)
  {
  	size_t ks;
  	void *mem = (void *)p;
  
  	if (unlikely(ZERO_OR_NULL_PTR(mem)))
  		return;
  	ks = ksize(mem);
  	memset(mem, 0, ks);
  	kfree(mem);
  }
  EXPORT_SYMBOL(kzfree);
  
  /* Tracepoints definitions. */
  EXPORT_TRACEPOINT_SYMBOL(kmalloc);
  EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
  EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
  EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
  EXPORT_TRACEPOINT_SYMBOL(kfree);
  EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);