mm/slab.h - kernel/common - Git at Google

 #ifndef MM_SLAB_H
 #define MM_SLAB_H
 /*
  * Internal slab definitions
  */

 #ifdef CONFIG_SLOB
 /*
  * Common fields provided in kmem_cache by all slab allocators
  * This struct is either used directly by the allocator (SLOB)
  * or the allocator must include definitions for all fields
  * provided in kmem_cache_common in their definition of kmem_cache.
  *
  * Once we can do anonymous structs (C11 standard) we could put a
  * anonymous struct definition in these allocators so that the
  * separate allocations in the kmem_cache structure of SLAB and
  * SLUB is no longer needed.
  */
 struct kmem_cache {
 	unsigned int object_size;/* The original size of the object */
 	unsigned int size;	/* The aligned/padded/added on size  */
 	unsigned int align;	/* Alignment as calculated */
 	unsigned long flags;	/* Active flags on the slab */
 	const char *name;	/* Slab name for sysfs */
 	int refcount;		/* Use counter */
 	void (*ctor)(void *);	/* Called on object slot creation */
 	struct list_head list;	/* List of all slab caches on the system */
 };

 #endif /* CONFIG_SLOB */

 #ifdef CONFIG_SLAB
 #include <linux/slab_def.h>
 #endif

 #ifdef CONFIG_SLUB
 #include <linux/slub_def.h>
 #endif

 #include <linux/memcontrol.h>
 #include <linux/fault-inject.h>
 #include <linux/kmemcheck.h>
 #include <linux/kasan.h>
 #include <linux/kmemleak.h>
 #include <linux/random.h>

 /*
  * State of the slab allocator.
  *
  * This is used to describe the states of the allocator during bootup.
  * Allocators use this to gradually bootstrap themselves. Most allocators
  * have the problem that the structures used for managing slab caches are
  * allocated from slab caches themselves.
  */
 enum slab_state {
 	DOWN,			/* No slab functionality yet */
 	PARTIAL,		/* SLUB: kmem_cache_node available */
 	PARTIAL_NODE,		/* SLAB: kmalloc size for node struct available */
 	UP,			/* Slab caches usable but not all extras yet */
 	FULL			/* Everything is working */
 };

 extern enum slab_state slab_state;

 /* The slab cache mutex protects the management structures during changes */
 extern struct mutex slab_mutex;

 /* The list of all slab caches on the system */
 extern struct list_head slab_caches;

 /* The slab cache that manages slab cache information */
 extern struct kmem_cache *kmem_cache;

 unsigned long calculate_alignment(unsigned long flags,
 		unsigned long align, unsigned long size);

 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
 void setup_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(unsigned long);

 /* Find the kmalloc slab corresponding for a certain size */
 struct kmem_cache *kmalloc_slab(size_t, gfp_t);
 #endif


 /* Functions provided by the slab allocators */
 extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);

 extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
 			unsigned long flags);
 extern void create_boot_cache(struct kmem_cache *, const char *name,
 			size_t size, unsigned long flags);

 int slab_unmergeable(struct kmem_cache *s);
 struct kmem_cache *find_mergeable(size_t size, size_t align,
 		unsigned long flags, const char *name, void (*ctor)(void *));
 #ifndef CONFIG_SLOB
 struct kmem_cache *
 __kmem_cache_alias(const char *name, size_t size, size_t align,
 		   unsigned long flags, void (*ctor)(void *));

 unsigned long kmem_cache_flags(unsigned long object_size,
 	unsigned long flags, const char *name,
 	void (*ctor)(void *));
 #else
 static inline struct kmem_cache *
 __kmem_cache_alias(const char *name, size_t size, size_t align,
 		   unsigned long flags, void (*ctor)(void *))
 { return NULL; }

 static inline unsigned long kmem_cache_flags(unsigned long object_size,
 	unsigned long flags, const char *name,
 	void (*ctor)(void *))
 {
 	return flags;
 }
 #endif


 /* Legal flag mask for kmem_cache_create(), for various configurations */
 #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
 			 SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )

 #if defined(CONFIG_DEBUG_SLAB)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
 #elif defined(CONFIG_SLUB_DEBUG)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
 			  SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
 #else
 #define SLAB_DEBUG_FLAGS (0)
 #endif

 #if defined(CONFIG_SLAB)
 #define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
 			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
 			  SLAB_NOTRACK | SLAB_ACCOUNT)
 #elif defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
 			  SLAB_TEMPORARY | SLAB_NOTRACK | SLAB_ACCOUNT)
 #else
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
 #endif

 #define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)

 int __kmem_cache_shutdown(struct kmem_cache *);
 void __kmem_cache_release(struct kmem_cache *);
 int __kmem_cache_shrink(struct kmem_cache *);
 void slab_kmem_cache_release(struct kmem_cache *);

 struct seq_file;
 struct file;

 struct slabinfo {
 	unsigned long active_objs;
 	unsigned long num_objs;
 	unsigned long active_slabs;
 	unsigned long num_slabs;
 	unsigned long shared_avail;
 	unsigned int limit;
 	unsigned int batchcount;
 	unsigned int shared;
 	unsigned int objects_per_slab;
 	unsigned int cache_order;
 };

 void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
 ssize_t slabinfo_write(struct file *file, const char __user *buffer,
 		       size_t count, loff_t *ppos);

 /*
  * Generic implementation of bulk operations
  * These are useful for situations in which the allocator cannot
  * perform optimizations. In that case segments of the object listed
  * may be allocated or freed using these operations.
  */
 void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
 int __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);

 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
 /*
  * Iterate over all memcg caches of the given root cache. The caller must hold
  * slab_mutex.
  */
 #define for_each_memcg_cache(iter, root) \
 	list_for_each_entry(iter, &(root)->memcg_params.list, \
 			    memcg_params.list)

 static inline bool is_root_cache(struct kmem_cache *s)
 {
 	return s->memcg_params.is_root_cache;
 }

 static inline bool slab_equal_or_root(struct kmem_cache *s,
 				      struct kmem_cache *p)
 {
 	return p == s || p == s->memcg_params.root_cache;
 }

 /*
  * We use suffixes to the name in memcg because we can't have caches
  * created in the system with the same name. But when we print them
  * locally, better refer to them with the base name
  */
 static inline const char *cache_name(struct kmem_cache *s)
 {
 	if (!is_root_cache(s))
 		s = s->memcg_params.root_cache;
 	return s->name;
 }

 /*
  * Note, we protect with RCU only the memcg_caches array, not per-memcg caches.
  * That said the caller must assure the memcg's cache won't go away by either
  * taking a css reference to the owner cgroup, or holding the slab_mutex.
  */
 static inline struct kmem_cache *
 cache_from_memcg_idx(struct kmem_cache *s, int idx)
 {
 	struct kmem_cache *cachep;
 	struct memcg_cache_array *arr;

 	rcu_read_lock();
 	arr = rcu_dereference(s->memcg_params.memcg_caches);

 	/*
 	 * Make sure we will access the up-to-date value. The code updating
 	 * memcg_caches issues a write barrier to match this (see
 	 * memcg_create_kmem_cache()).
 	 */
 	cachep = lockless_dereference(arr->entries[idx]);
 	rcu_read_unlock();

 	return cachep;
 }

 static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
 {
 	if (is_root_cache(s))
 		return s;
 	return s->memcg_params.root_cache;
 }

 static __always_inline int memcg_charge_slab(struct page *page,
 					     gfp_t gfp, int order,
 					     struct kmem_cache *s)
 {
 	int ret;

 	if (!memcg_kmem_enabled())
 		return 0;
 	if (is_root_cache(s))
 		return 0;

 	ret = memcg_kmem_charge_memcg(page, gfp, order, s->memcg_params.memcg);
 	if (ret)
 		return ret;

 	memcg_kmem_update_page_stat(page,
 			(s->flags & SLAB_RECLAIM_ACCOUNT) ?
 			MEMCG_SLAB_RECLAIMABLE : MEMCG_SLAB_UNRECLAIMABLE,
 			1 << order);
 	return 0;
 }

 static __always_inline void memcg_uncharge_slab(struct page *page, int order,
 						struct kmem_cache *s)
 {
 	if (!memcg_kmem_enabled())
 		return;

 	memcg_kmem_update_page_stat(page,
 			(s->flags & SLAB_RECLAIM_ACCOUNT) ?
 			MEMCG_SLAB_RECLAIMABLE : MEMCG_SLAB_UNRECLAIMABLE,
 			-(1 << order));
 	memcg_kmem_uncharge(page, order);
 }

 extern void slab_init_memcg_params(struct kmem_cache *);

 #else /* CONFIG_MEMCG && !CONFIG_SLOB */

 #define for_each_memcg_cache(iter, root) \
 	for ((void)(iter), (void)(root); 0; )

 static inline bool is_root_cache(struct kmem_cache *s)
 {
 	return true;
 }

 static inline bool slab_equal_or_root(struct kmem_cache *s,
 				      struct kmem_cache *p)
 {
 	return true;
 }

 static inline const char *cache_name(struct kmem_cache *s)
 {
 	return s->name;
 }

 static inline struct kmem_cache *
 cache_from_memcg_idx(struct kmem_cache *s, int idx)
 {
 	return NULL;
 }

 static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
 {
 	return s;
 }

 static inline int memcg_charge_slab(struct page *page, gfp_t gfp, int order,
 				    struct kmem_cache *s)
 {
 	return 0;
 }

 static inline void memcg_uncharge_slab(struct page *page, int order,
 				       struct kmem_cache *s)
 {
 }

 static inline void slab_init_memcg_params(struct kmem_cache *s)
 {
 }
 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */

 static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
 {
 	struct kmem_cache *cachep;
 	struct page *page;

 	/*
 	 * When kmemcg is not being used, both assignments should return the
 	 * same value. but we don't want to pay the assignment price in that
 	 * case. If it is not compiled in, the compiler should be smart enough
 	 * to not do even the assignment. In that case, slab_equal_or_root
 	 * will also be a constant.
 	 */
 	if (!memcg_kmem_enabled() &&
 	    !unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
 		return s;

 	page = virt_to_head_page(x);
 	cachep = page->slab_cache;
 	if (slab_equal_or_root(cachep, s))
 		return cachep;

 	pr_err("%s: Wrong slab cache. %s but object is from %s\n",
 	       __func__, s->name, cachep->name);
 	WARN_ON_ONCE(1);
 	return s;
 }

 static inline size_t slab_ksize(const struct kmem_cache *s)
 {
 #ifndef CONFIG_SLUB
 	return s->object_size;

 #else /* CONFIG_SLUB */
 # ifdef CONFIG_SLUB_DEBUG
 	/*
 	 * Debugging requires use of the padding between object
 	 * and whatever may come after it.
 	 */
 	if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
 		return s->object_size;
 # endif
 	if (s->flags & SLAB_KASAN)
 		return s->object_size;
 	/*
 	 * If we have the need to store the freelist pointer
 	 * back there or track user information then we can
 	 * only use the space before that information.
 	 */
 	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
 		return s->inuse;
 	/*
 	 * Else we can use all the padding etc for the allocation
 	 */
 	return s->size;
 #endif
 }

 static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
 						     gfp_t flags)
 {
 	flags &= gfp_allowed_mask;
 	lockdep_trace_alloc(flags);
 	might_sleep_if(gfpflags_allow_blocking(flags));

 	if (should_failslab(s, flags))
 		return NULL;

 	if (memcg_kmem_enabled() &&
 	    ((flags & __GFP_ACCOUNT) || (s->flags & SLAB_ACCOUNT)))
 		return memcg_kmem_get_cache(s);

 	return s;
 }

 static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
 					size_t size, void **p)
 {
 	size_t i;

 	flags &= gfp_allowed_mask;
 	for (i = 0; i < size; i++) {
 		void *object = p[i];

 		kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
 		kmemleak_alloc_recursive(object, s->object_size, 1,
 					 s->flags, flags);
 		kasan_slab_alloc(s, object, flags);
 	}

 	if (memcg_kmem_enabled())
 		memcg_kmem_put_cache(s);
 }

 #ifndef CONFIG_SLOB
 /*
  * The slab lists for all objects.
  */
 struct kmem_cache_node {
 	spinlock_t list_lock;

 #ifdef CONFIG_SLAB
 	struct list_head slabs_partial;	/* partial list first, better asm code */
 	struct list_head slabs_full;
 	struct list_head slabs_free;
 	unsigned long num_slabs;
 	unsigned long free_objects;
 	unsigned int free_limit;
 	unsigned int colour_next;	/* Per-node cache coloring */
 	struct array_cache *shared;	/* shared per node */
 	struct alien_cache **alien;	/* on other nodes */
 	unsigned long next_reap;	/* updated without locking */
 	int free_touched;		/* updated without locking */
 #endif

 #ifdef CONFIG_SLUB
 	unsigned long nr_partial;
 	struct list_head partial;
 #ifdef CONFIG_SLUB_DEBUG
 	atomic_long_t nr_slabs;
 	atomic_long_t total_objects;
 	struct list_head full;
 #endif
 #endif

 };

 static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
 {
 	return s->node[node];
 }

 /*
  * Iterator over all nodes. The body will be executed for each node that has
  * a kmem_cache_node structure allocated (which is true for all online nodes)
  */
 #define for_each_kmem_cache_node(__s, __node, __n) \
 	for (__node = 0; __node < nr_node_ids; __node++) \
 		 if ((__n = get_node(__s, __node)))

 #endif

 void *slab_start(struct seq_file *m, loff_t *pos);
 void *slab_next(struct seq_file *m, void *p, loff_t *pos);
 void slab_stop(struct seq_file *m, void *p);
 int memcg_slab_show(struct seq_file *m, void *p);

 void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr);

 #ifdef CONFIG_SLAB_FREELIST_RANDOM
 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
 			gfp_t gfp);
 void cache_random_seq_destroy(struct kmem_cache *cachep);
 #else
 static inline int cache_random_seq_create(struct kmem_cache *cachep,
 					unsigned int count, gfp_t gfp)
 {
 	return 0;
 }
 static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
 #endif /* CONFIG_SLAB_FREELIST_RANDOM */

 #endif /* MM_SLAB_H */
	#ifndef MM_SLAB_H
	#define MM_SLAB_H
	/*
	* Internal slab definitions
	*/

	#ifdef CONFIG_SLOB
	/*
	* Common fields provided in kmem_cache by all slab allocators
	* This struct is either used directly by the allocator (SLOB)
	* or the allocator must include definitions for all fields
	* provided in kmem_cache_common in their definition of kmem_cache.
	*
	* Once we can do anonymous structs (C11 standard) we could put a
	* anonymous struct definition in these allocators so that the
	* separate allocations in the kmem_cache structure of SLAB and
	* SLUB is no longer needed.
	*/
	struct kmem_cache {
	unsigned int object_size;/* The original size of the object */
	unsigned int size; /* The aligned/padded/added on size */
	unsigned int align; /* Alignment as calculated */
	unsigned long flags; /* Active flags on the slab */
	const char name; / Slab name for sysfs */
	int refcount; /* Use counter */
	void (ctor)(void ); /* Called on object slot creation */
	struct list_head list; /* List of all slab caches on the system */
	};

	#endif /* CONFIG_SLOB */

	#ifdef CONFIG_SLAB
	#include <linux/slab_def.h>
	#endif

	#ifdef CONFIG_SLUB
	#include <linux/slub_def.h>
	#endif

	#include <linux/memcontrol.h>
	#include <linux/fault-inject.h>
	#include <linux/kmemcheck.h>
	#include <linux/kasan.h>
	#include <linux/kmemleak.h>
	#include <linux/random.h>

	/*
	* State of the slab allocator.
	*
	* This is used to describe the states of the allocator during bootup.
	* Allocators use this to gradually bootstrap themselves. Most allocators
	* have the problem that the structures used for managing slab caches are
	* allocated from slab caches themselves.
	*/
	enum slab_state {
	DOWN, /* No slab functionality yet */
	PARTIAL, /* SLUB: kmem_cache_node available */
	PARTIAL_NODE, /* SLAB: kmalloc size for node struct available */
	UP, /* Slab caches usable but not all extras yet */
	FULL /* Everything is working */
	};

	extern enum slab_state slab_state;

	/* The slab cache mutex protects the management structures during changes */
	extern struct mutex slab_mutex;

	/* The list of all slab caches on the system */
	extern struct list_head slab_caches;

	/* The slab cache that manages slab cache information */
	extern struct kmem_cache *kmem_cache;

	unsigned long calculate_alignment(unsigned long flags,
	unsigned long align, unsigned long size);

	#ifndef CONFIG_SLOB
	/* Kmalloc array related functions */
	void setup_kmalloc_cache_index_table(void);
	void create_kmalloc_caches(unsigned long);

	/* Find the kmalloc slab corresponding for a certain size */
	struct kmem_cache *kmalloc_slab(size_t, gfp_t);
	#endif


	/* Functions provided by the slab allocators */
	extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);

	extern struct kmem_cache create_kmalloc_cache(const char name, size_t size,
	unsigned long flags);
	extern void create_boot_cache(struct kmem_cache , const char name,
	size_t size, unsigned long flags);

	int slab_unmergeable(struct kmem_cache *s);
	struct kmem_cache *find_mergeable(size_t size, size_t align,
	unsigned long flags, const char name, void (ctor)(void *));
	#ifndef CONFIG_SLOB
	struct kmem_cache *
	__kmem_cache_alias(const char *name, size_t size, size_t align,
	unsigned long flags, void (ctor)(void ));

	unsigned long kmem_cache_flags(unsigned long object_size,
	unsigned long flags, const char *name,
	void (ctor)(void ));
	#else
	static inline struct kmem_cache *
	__kmem_cache_alias(const char *name, size_t size, size_t align,
	unsigned long flags, void (ctor)(void ))
	{ return NULL; }

	static inline unsigned long kmem_cache_flags(unsigned long object_size,
	unsigned long flags, const char *name,
	void (ctor)(void ))
	{
	return flags;
	}
	#endif


	/* Legal flag mask for kmem_cache_create(), for various configurations */
	#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN \| SLAB_CACHE_DMA \| SLAB_PANIC \| \
	SLAB_DESTROY_BY_RCU \| SLAB_DEBUG_OBJECTS )

	#if defined(CONFIG_DEBUG_SLAB)
	#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE \| SLAB_POISON \| SLAB_STORE_USER)
	#elif defined(CONFIG_SLUB_DEBUG)
	#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE \| SLAB_POISON \| SLAB_STORE_USER \| \
	SLAB_TRACE \| SLAB_CONSISTENCY_CHECKS)
	#else
	#define SLAB_DEBUG_FLAGS (0)
	#endif

	#if defined(CONFIG_SLAB)
	#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD \| SLAB_NOLEAKTRACE \| \
	SLAB_RECLAIM_ACCOUNT \| SLAB_TEMPORARY \| \
	SLAB_NOTRACK \| SLAB_ACCOUNT)
	#elif defined(CONFIG_SLUB)
	#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE \| SLAB_RECLAIM_ACCOUNT \| \
	SLAB_TEMPORARY \| SLAB_NOTRACK \| SLAB_ACCOUNT)
	#else
	#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
	#endif

	#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS \| SLAB_DEBUG_FLAGS \| SLAB_CACHE_FLAGS)

	int __kmem_cache_shutdown(struct kmem_cache *);
	void __kmem_cache_release(struct kmem_cache *);
	int __kmem_cache_shrink(struct kmem_cache *);
	void slab_kmem_cache_release(struct kmem_cache *);

	struct seq_file;
	struct file;

	struct slabinfo {
	unsigned long active_objs;
	unsigned long num_objs;
	unsigned long active_slabs;
	unsigned long num_slabs;
	unsigned long shared_avail;
	unsigned int limit;
	unsigned int batchcount;
	unsigned int shared;
	unsigned int objects_per_slab;
	unsigned int cache_order;
	};

	void get_slabinfo(struct kmem_cache s, struct slabinfo sinfo);
	void slabinfo_show_stats(struct seq_file m, struct kmem_cache s);
	ssize_t slabinfo_write(struct file file, const char __user buffer,
	size_t count, loff_t *ppos);

	/*
	* Generic implementation of bulk operations
	* These are useful for situations in which the allocator cannot
	* perform optimizations. In that case segments of the object listed
	* may be allocated or freed using these operations.
	*/
	void __kmem_cache_free_bulk(struct kmem_cache , size_t, void *);
	int __kmem_cache_alloc_bulk(struct kmem_cache , gfp_t, size_t, void *);

	#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
	/*
	* Iterate over all memcg caches of the given root cache. The caller must hold
	* slab_mutex.
	*/
	#define for_each_memcg_cache(iter, root) \
	list_for_each_entry(iter, &(root)->memcg_params.list, \
	memcg_params.list)

	static inline bool is_root_cache(struct kmem_cache *s)
	{
	return s->memcg_params.is_root_cache;
	}

	static inline bool slab_equal_or_root(struct kmem_cache *s,
	struct kmem_cache *p)
	{
	return p == s \|\| p == s->memcg_params.root_cache;
	}

	/*
	* We use suffixes to the name in memcg because we can't have caches
	* created in the system with the same name. But when we print them
	* locally, better refer to them with the base name
	*/
	static inline const char cache_name(struct kmem_cache s)
	{
	if (!is_root_cache(s))
	s = s->memcg_params.root_cache;
	return s->name;
	}

	/*
	* Note, we protect with RCU only the memcg_caches array, not per-memcg caches.
	* That said the caller must assure the memcg's cache won't go away by either
	* taking a css reference to the owner cgroup, or holding the slab_mutex.
	*/
	static inline struct kmem_cache *
	cache_from_memcg_idx(struct kmem_cache *s, int idx)
	{
	struct kmem_cache *cachep;
	struct memcg_cache_array *arr;

	rcu_read_lock();
	arr = rcu_dereference(s->memcg_params.memcg_caches);

	/*
	* Make sure we will access the up-to-date value. The code updating
	* memcg_caches issues a write barrier to match this (see
	* memcg_create_kmem_cache()).
	*/
	cachep = lockless_dereference(arr->entries[idx]);
	rcu_read_unlock();

	return cachep;
	}

	static inline struct kmem_cache memcg_root_cache(struct kmem_cache s)
	{
	if (is_root_cache(s))
	return s;
	return s->memcg_params.root_cache;
	}

	static __always_inline int memcg_charge_slab(struct page *page,
	gfp_t gfp, int order,
	struct kmem_cache *s)
	{
	int ret;

	if (!memcg_kmem_enabled())
	return 0;
	if (is_root_cache(s))
	return 0;

	ret = memcg_kmem_charge_memcg(page, gfp, order, s->memcg_params.memcg);
	if (ret)
	return ret;

	memcg_kmem_update_page_stat(page,
	(s->flags & SLAB_RECLAIM_ACCOUNT) ?
	MEMCG_SLAB_RECLAIMABLE : MEMCG_SLAB_UNRECLAIMABLE,
	1 << order);
	return 0;
	}

	static __always_inline void memcg_uncharge_slab(struct page *page, int order,
	struct kmem_cache *s)
	{
	if (!memcg_kmem_enabled())
	return;

	memcg_kmem_update_page_stat(page,
	(s->flags & SLAB_RECLAIM_ACCOUNT) ?
	MEMCG_SLAB_RECLAIMABLE : MEMCG_SLAB_UNRECLAIMABLE,
	-(1 << order));
	memcg_kmem_uncharge(page, order);
	}

	extern void slab_init_memcg_params(struct kmem_cache *);

	#else /* CONFIG_MEMCG && !CONFIG_SLOB */

	#define for_each_memcg_cache(iter, root) \
	for ((void)(iter), (void)(root); 0; )

	static inline bool is_root_cache(struct kmem_cache *s)
	{
	return true;
	}

	static inline bool slab_equal_or_root(struct kmem_cache *s,
	struct kmem_cache *p)
	{
	return true;
	}

	static inline const char cache_name(struct kmem_cache s)
	{
	return s->name;
	}

	static inline struct kmem_cache *
	cache_from_memcg_idx(struct kmem_cache *s, int idx)
	{
	return NULL;
	}

	static inline struct kmem_cache memcg_root_cache(struct kmem_cache s)
	{
	return s;
	}

	static inline int memcg_charge_slab(struct page *page, gfp_t gfp, int order,
	struct kmem_cache *s)
	{
	return 0;
	}

	static inline void memcg_uncharge_slab(struct page *page, int order,
	struct kmem_cache *s)
	{
	}

	static inline void slab_init_memcg_params(struct kmem_cache *s)
	{
	}
	#endif /* CONFIG_MEMCG && !CONFIG_SLOB */

	static inline struct kmem_cache cache_from_obj(struct kmem_cache s, void *x)
	{
	struct kmem_cache *cachep;
	struct page *page;

	/*
	* When kmemcg is not being used, both assignments should return the
	* same value. but we don't want to pay the assignment price in that
	* case. If it is not compiled in, the compiler should be smart enough
	* to not do even the assignment. In that case, slab_equal_or_root
	* will also be a constant.
	*/
	if (!memcg_kmem_enabled() &&
	!unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
	return s;

	page = virt_to_head_page(x);
	cachep = page->slab_cache;
	if (slab_equal_or_root(cachep, s))
	return cachep;

	pr_err("%s: Wrong slab cache. %s but object is from %s\n",
	__func__, s->name, cachep->name);
	WARN_ON_ONCE(1);
	return s;
	}

	static inline size_t slab_ksize(const struct kmem_cache *s)
	{
	#ifndef CONFIG_SLUB
	return s->object_size;

	#else /* CONFIG_SLUB */
	# ifdef CONFIG_SLUB_DEBUG
	/*
	* Debugging requires use of the padding between object
	* and whatever may come after it.
	*/
	if (s->flags & (SLAB_RED_ZONE \| SLAB_POISON))
	return s->object_size;
	# endif
	if (s->flags & SLAB_KASAN)
	return s->object_size;
	/*
	* If we have the need to store the freelist pointer
	* back there or track user information then we can
	* only use the space before that information.
	*/
	if (s->flags & (SLAB_DESTROY_BY_RCU \| SLAB_STORE_USER))
	return s->inuse;
	/*
	* Else we can use all the padding etc for the allocation
	*/
	return s->size;
	#endif
	}

	static inline struct kmem_cache slab_pre_alloc_hook(struct kmem_cache s,
	gfp_t flags)
	{
	flags &= gfp_allowed_mask;
	lockdep_trace_alloc(flags);
	might_sleep_if(gfpflags_allow_blocking(flags));

	if (should_failslab(s, flags))
	return NULL;

	if (memcg_kmem_enabled() &&
	((flags & __GFP_ACCOUNT) \|\| (s->flags & SLAB_ACCOUNT)))
	return memcg_kmem_get_cache(s);

	return s;
	}

	static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
	size_t size, void **p)
	{
	size_t i;

	flags &= gfp_allowed_mask;
	for (i = 0; i < size; i++) {
	void *object = p[i];

	kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
	kmemleak_alloc_recursive(object, s->object_size, 1,
	s->flags, flags);
	kasan_slab_alloc(s, object, flags);
	}

	if (memcg_kmem_enabled())
	memcg_kmem_put_cache(s);
	}

	#ifndef CONFIG_SLOB
	/*
	* The slab lists for all objects.
	*/
	struct kmem_cache_node {
	spinlock_t list_lock;

	#ifdef CONFIG_SLAB
	struct list_head slabs_partial; /* partial list first, better asm code */
	struct list_head slabs_full;
	struct list_head slabs_free;
	unsigned long num_slabs;
	unsigned long free_objects;
	unsigned int free_limit;
	unsigned int colour_next; /* Per-node cache coloring */
	struct array_cache shared; / shared per node */
	struct alien_cache *alien; / on other nodes */
	unsigned long next_reap; /* updated without locking */
	int free_touched; /* updated without locking */
	#endif

	#ifdef CONFIG_SLUB
	unsigned long nr_partial;
	struct list_head partial;
	#ifdef CONFIG_SLUB_DEBUG
	atomic_long_t nr_slabs;
	atomic_long_t total_objects;
	struct list_head full;
	#endif
	#endif

	};

	static inline struct kmem_cache_node get_node(struct kmem_cache s, int node)
	{
	return s->node[node];
	}

	/*
	* Iterator over all nodes. The body will be executed for each node that has
	* a kmem_cache_node structure allocated (which is true for all online nodes)
	*/
	#define for_each_kmem_cache_node(__s, __node, __n) \
	for (__node = 0; __node < nr_node_ids; __node++) \
	if ((__n = get_node(__s, __node)))

	#endif

	void slab_start(struct seq_file m, loff_t *pos);
	void slab_next(struct seq_file m, void p, loff_t pos);
	void slab_stop(struct seq_file m, void p);
	int memcg_slab_show(struct seq_file m, void p);

	void ___cache_free(struct kmem_cache cache, void x, unsigned long addr);

	#ifdef CONFIG_SLAB_FREELIST_RANDOM
	int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
	gfp_t gfp);
	void cache_random_seq_destroy(struct kmem_cache *cachep);
	#else
	static inline int cache_random_seq_create(struct kmem_cache *cachep,
	unsigned int count, gfp_t gfp)
	{
	return 0;
	}
	static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
	#endif /* CONFIG_SLAB_FREELIST_RANDOM */

	#endif /* MM_SLAB_H */