linux/mm/slab.h

/* SPDX-License-Identifier: GPL-2.0 */
#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 */
	slab_flags_t flags;	/* Active flags on the slab */
	unsigned int useroffset;/* Usercopy region offset */
	unsigned int usersize;	/* Usercopy region size */
	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/kasan.h>
#include <linux/kmemleak.h>
#include <linux/random.h>
#include <linux/sched/mm.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;

/* A table of kmalloc cache names and sizes */
extern const struct kmalloc_info_struct {
	const char *name[NR_KMALLOC_TYPES];
	unsigned int size;
} kmalloc_info[];

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

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

gfp_t kmalloc_fix_flags(gfp_t flags);

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

struct kmem_cache *create_kmalloc_cache(const char *name, unsigned int size,
			slab_flags_t flags, unsigned int useroffset,
			unsigned int usersize);
extern void create_boot_cache(struct kmem_cache *, const char *name,
			unsigned int size, slab_flags_t flags,
			unsigned int useroffset, unsigned int usersize);

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

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

static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
	slab_flags_t 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_CACHE_DMA32 | SLAB_PANIC | \
			 SLAB_TYPESAFE_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_ACCOUNT)
#elif defined(CONFIG_SLUB)
#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
			  SLAB_TEMPORARY | SLAB_ACCOUNT)
#else
#define SLAB_CACHE_FLAGS (0)
#endif

/* Common flags available with current configuration */
#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)

/* Common flags permitted for kmem_cache_create */
#define SLAB_FLAGS_PERMITTED (SLAB_CORE_FLAGS | \
			      SLAB_RED_ZONE | \
			      SLAB_POISON | \
			      SLAB_STORE_USER | \
			      SLAB_TRACE | \
			      SLAB_CONSISTENCY_CHECKS | \
			      SLAB_MEM_SPREAD | \
			      SLAB_NOLEAKTRACE | \
			      SLAB_RECLAIM_ACCOUNT | \
			      SLAB_TEMPORARY | \
			      SLAB_ACCOUNT)

bool __kmem_cache_empty(struct kmem_cache *);
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 **);

static inline int cache_vmstat_idx(struct kmem_cache *s)
{
	return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
		NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B;
}

#ifdef CONFIG_SLUB_DEBUG
#ifdef CONFIG_SLUB_DEBUG_ON
DECLARE_STATIC_KEY_TRUE(slub_debug_enabled);
#else
DECLARE_STATIC_KEY_FALSE(slub_debug_enabled);
#endif
extern void print_tracking(struct kmem_cache *s, void *object);
#else
static inline void print_tracking(struct kmem_cache *s, void *object)
{
}
#endif

/*
 * Returns true if any of the specified slub_debug flags is enabled for the
 * cache. Use only for flags parsed by setup_slub_debug() as it also enables
 * the static key.
 */
static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t flags)
{
#ifdef CONFIG_SLUB_DEBUG
	VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS));
	if (static_branch_unlikely(&slub_debug_enabled))
		return s->flags & flags;
#endif
	return false;
}

#ifdef CONFIG_MEMCG_KMEM
static inline struct obj_cgroup **page_obj_cgroups(struct page *page)
{
	/*
	 * page->mem_cgroup and page->obj_cgroups are sharing the same
	 * space. To distinguish between them in case we don't know for sure
	 * that the page is a slab page (e.g. page_cgroup_ino()), let's
	 * always set the lowest bit of obj_cgroups.
	 */
	return (struct obj_cgroup **)
		((unsigned long)page->obj_cgroups & ~0x1UL);
}

static inline bool page_has_obj_cgroups(struct page *page)
{
	return ((unsigned long)page->obj_cgroups & 0x1UL);
}

int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s,
				 gfp_t gfp);

static inline void memcg_free_page_obj_cgroups(struct page *page)
{
	kfree(page_obj_cgroups(page));
	page->obj_cgroups = NULL;
}

static inline size_t obj_full_size(struct kmem_cache *s)
{
	/*
	 * For each accounted object there is an extra space which is used
	 * to store obj_cgroup membership. Charge it too.
	 */
	return s->size + sizeof(struct obj_cgroup *);
}

/*
 * Returns false if the allocation should fail.
 */
static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,
					     struct obj_cgroup **objcgp,
					     size_t objects, gfp_t flags)
{
	struct obj_cgroup *objcg;

	if (!memcg_kmem_enabled())
		return true;

	if (!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT))
		return true;

	objcg = get_obj_cgroup_from_current();
	if (!objcg)
		return true;

	if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) {
		obj_cgroup_put(objcg);
		return false;
	}

	*objcgp = objcg;
	return true;
}

static inline void mod_objcg_state(struct obj_cgroup *objcg,
				   struct pglist_data *pgdat,
				   int idx, int nr)
{
	struct mem_cgroup *memcg;
	struct lruvec *lruvec;

	rcu_read_lock();
	memcg = obj_cgroup_memcg(objcg);
	lruvec = mem_cgroup_lruvec(memcg, pgdat);
	mod_memcg_lruvec_state(lruvec, idx, nr);
	rcu_read_unlock();
}

static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
					      struct obj_cgroup *objcg,
					      gfp_t flags, size_t size,
					      void **p)
{
	struct page *page;
	unsigned long off;
	size_t i;

	if (!memcg_kmem_enabled() || !objcg)
		return;

	flags &= ~__GFP_ACCOUNT;
	for (i = 0; i < size; i++) {
		if (likely(p[i])) {
			page = virt_to_head_page(p[i]);

			if (!page_has_obj_cgroups(page) &&
			    memcg_alloc_page_obj_cgroups(page, s, flags)) {
				obj_cgroup_uncharge(objcg, obj_full_size(s));
				continue;
			}

			off = obj_to_index(s, page, p[i]);
			obj_cgroup_get(objcg);
			page_obj_cgroups(page)[off] = objcg;
			mod_objcg_state(objcg, page_pgdat(page),
					cache_vmstat_idx(s), obj_full_size(s));
		} else {
			obj_cgroup_uncharge(objcg, obj_full_size(s));
		}
	}
	obj_cgroup_put(objcg);
}

static inline void memcg_slab_free_hook(struct kmem_cache *s_orig,
					void **p, int objects)
{
	struct kmem_cache *s;
	struct obj_cgroup *objcg;
	struct page *page;
	unsigned int off;
	int i;

	if (!memcg_kmem_enabled())
		return;

	for (i = 0; i < objects; i++) {
		if (unlikely(!p[i]))
			continue;

		page = virt_to_head_page(p[i]);
		if (!page_has_obj_cgroups(page))
			continue;

		if (!s_orig)
			s = page->slab_cache;
		else
			s = s_orig;

		off = obj_to_index(s, page, p[i]);
		objcg = page_obj_cgroups(page)[off];
		if (!objcg)
			continue;

		page_obj_cgroups(page)[off] = NULL;
		obj_cgroup_uncharge(objcg, obj_full_size(s));
		mod_objcg_state(objcg, page_pgdat(page), cache_vmstat_idx(s),
				-obj_full_size(s));
		obj_cgroup_put(objcg);
	}
}

#else /* CONFIG_MEMCG_KMEM */
static inline bool page_has_obj_cgroups(struct page *page)
{
	return false;
}

static inline struct mem_cgroup *memcg_from_slab_obj(void *ptr)
{
	return NULL;
}

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

static inline void memcg_free_page_obj_cgroups(struct page *page)
{
}

static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,
					     struct obj_cgroup **objcgp,
					     size_t objects, gfp_t flags)
{
	return true;
}

static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
					      struct obj_cgroup *objcg,
					      gfp_t flags, size_t size,
					      void **p)
{
}

static inline void memcg_slab_free_hook(struct kmem_cache *s,
					void **p, int objects)
{
}
#endif /* CONFIG_MEMCG_KMEM */

static inline struct kmem_cache *virt_to_cache(const void *obj)
{
	struct page *page;

	page = virt_to_head_page(obj);
	if (WARN_ONCE(!PageSlab(page), "%s: Object is not a Slab page!\n",
					__func__))
		return NULL;
	return page->slab_cache;
}

static __always_inline void account_slab_page(struct page *page, int order,
					      struct kmem_cache *s)
{
	mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
			    PAGE_SIZE << order);
}

static __always_inline void unaccount_slab_page(struct page *page, int order,
						struct kmem_cache *s)
{
	if (memcg_kmem_enabled())
		memcg_free_page_obj_cgroups(page);

	mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
			    -(PAGE_SIZE << order));
}

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

	if (!IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
	    !kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS))
		return s;

	cachep = virt_to_cache(x);
	if (WARN(cachep && cachep != s,
		  "%s: Wrong slab cache. %s but object is from %s\n",
		  __func__, s->name, cachep->name))
		print_tracking(cachep, x);
	return cachep;
}

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_TYPESAFE_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,
						     struct obj_cgroup **objcgp,
						     size_t size, gfp_t flags)
{
	flags &= gfp_allowed_mask;

	fs_reclaim_acquire(flags);
	fs_reclaim_release(flags);

	might_sleep_if(gfpflags_allow_blocking(flags));

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

	if (!memcg_slab_pre_alloc_hook(s, objcgp, size, flags))
		return NULL;

	return s;
}

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

	flags &= gfp_allowed_mask;
	for (i = 0; i < size; i++) {
		p[i] = kasan_slab_alloc(s, p[i], flags);
		/* As p[i] might get tagged, call kmemleak hook after KASAN. */
		kmemleak_alloc_recursive(p[i], s->object_size, 1,
					 s->flags, flags);
	}

	memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
}

#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 total_slabs;	/* length of all slab lists */
	unsigned long free_slabs;	/* length of free slab list only */
	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);

#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
void dump_unreclaimable_slab(void);
#else
static inline void dump_unreclaimable_slab(void)
{
}
#endif

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 */

static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
{
	if (static_branch_unlikely(&init_on_alloc)) {
		if (c->ctor)
			return false;
		if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
			return flags & __GFP_ZERO;
		return true;
	}
	return flags & __GFP_ZERO;
}

static inline bool slab_want_init_on_free(struct kmem_cache *c)
{
	if (static_branch_unlikely(&init_on_free))
		return !(c->ctor ||
			 (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)));
	return false;
}

#endif /* MM_SLAB_H */