mm/swapfile.c: tmp is always smaller than max

[thirdparty/linux.git] / 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 */
};

#else /* !CONFIG_SLOB */

struct memcg_cache_array {
        struct rcu_head rcu;
        struct kmem_cache *entries[0];
};

/*
 * This is the main placeholder for memcg-related information in kmem caches.
 * Both the root cache and the child caches will have it. For the root cache,
 * this will hold a dynamically allocated array large enough to hold
 * information about the currently limited memcgs in the system. To allow the
 * array to be accessed without taking any locks, on relocation we free the old
 * version only after a grace period.
 *
 * Root and child caches hold different metadata.
 *
 * @root_cache: Common to root and child caches.  NULL for root, pointer to
 *              the root cache for children.
 *
 * The following fields are specific to root caches.
 *
 * @memcg_caches: kmemcg ID indexed table of child caches.  This table is
 *              used to index child cachces during allocation and cleared
 *              early during shutdown.
 *
 * @root_caches_node: List node for slab_root_caches list.
 *
 * @children:   List of all child caches.  While the child caches are also
 *              reachable through @memcg_caches, a child cache remains on
 *              this list until it is actually destroyed.
 *
 * The following fields are specific to child caches.
 *
 * @memcg:      Pointer to the memcg this cache belongs to.
 *
 * @children_node: List node for @root_cache->children list.
 *
 * @kmem_caches_node: List node for @memcg->kmem_caches list.
 */
struct memcg_cache_params {
        struct kmem_cache *root_cache;
        union {
                struct {
                        struct memcg_cache_array __rcu *memcg_caches;
                        struct list_head __root_caches_node;
                        struct list_head children;
                        bool dying;
                };
                struct {
                        struct mem_cgroup *memcg;
                        struct list_head children_node;
                        struct list_head kmem_caches_node;
                        struct percpu_ref refcnt;

                        void (*work_fn)(struct kmem_cache *);
                        union {
                                struct rcu_head rcu_head;
                                struct work_struct work;
                        };
                };
        };
};
#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


/* 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 __kmemcg_cache_deactivate(struct kmem_cache *s);
void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s);
void slab_kmem_cache_release(struct kmem_cache *);
void kmem_cache_shrink_all(struct kmem_cache *s);

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 : NR_SLAB_UNRECLAIMABLE;
}

#ifdef CONFIG_MEMCG_KMEM

/* List of all root caches. */
extern struct list_head         slab_root_caches;
#define root_caches_node        memcg_params.__root_caches_node

/*
 * 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.children, \
                            memcg_params.children_node)

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

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;
}

/*
 * Expects a pointer to a slab page. Please note, that PageSlab() check
 * isn't sufficient, as it returns true also for tail compound slab pages,
 * which do not have slab_cache pointer set.
 * So this function assumes that the page can pass PageSlab() && !PageTail()
 * check.
 *
 * The kmem_cache can be reparented asynchronously. The caller must ensure
 * the memcg lifetime, e.g. by taking rcu_read_lock() or cgroup_mutex.
 */
static inline struct mem_cgroup *memcg_from_slab_page(struct page *page)
{
        struct kmem_cache *s;

        s = READ_ONCE(page->slab_cache);
        if (s && !is_root_cache(s))
                return READ_ONCE(s->memcg_params.memcg);

        return NULL;
}

/*
 * Charge the slab page belonging to the non-root kmem_cache.
 * Can be called for non-root kmem_caches only.
 */
static __always_inline int memcg_charge_slab(struct page *page,
                                             gfp_t gfp, int order,
                                             struct kmem_cache *s)
{
        unsigned int nr_pages = 1 << order;
        struct mem_cgroup *memcg;
        struct lruvec *lruvec;
        int ret;

        rcu_read_lock();
        memcg = READ_ONCE(s->memcg_params.memcg);
        while (memcg && !css_tryget_online(&memcg->css))
                memcg = parent_mem_cgroup(memcg);
        rcu_read_unlock();

        if (unlikely(!memcg || mem_cgroup_is_root(memcg))) {
                mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
                                    nr_pages);
                percpu_ref_get_many(&s->memcg_params.refcnt, nr_pages);
                return 0;
        }

        ret = memcg_kmem_charge(memcg, gfp, nr_pages);
        if (ret)
                goto out;

        lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page));
        mod_lruvec_state(lruvec, cache_vmstat_idx(s), nr_pages);

        /* transer try_charge() page references to kmem_cache */
        percpu_ref_get_many(&s->memcg_params.refcnt, nr_pages);
        css_put_many(&memcg->css, nr_pages);
out:
        css_put(&memcg->css);
        return ret;
}

/*
 * Uncharge a slab page belonging to a non-root kmem_cache.
 * Can be called for non-root kmem_caches only.
 */
static __always_inline void memcg_uncharge_slab(struct page *page, int order,
                                                struct kmem_cache *s)
{
        unsigned int nr_pages = 1 << order;
        struct mem_cgroup *memcg;
        struct lruvec *lruvec;

        rcu_read_lock();
        memcg = READ_ONCE(s->memcg_params.memcg);
        if (likely(!mem_cgroup_is_root(memcg))) {
                lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page));
                mod_lruvec_state(lruvec, cache_vmstat_idx(s), -nr_pages);
                memcg_kmem_uncharge(memcg, nr_pages);
        } else {
                mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
                                    -nr_pages);
        }
        rcu_read_unlock();

        percpu_ref_put_many(&s->memcg_params.refcnt, nr_pages);
}

extern void slab_init_memcg_params(struct kmem_cache *);
extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg);

#else /* CONFIG_MEMCG_KMEM */

/* If !memcg, all caches are root. */
#define slab_root_caches        slab_caches
#define root_caches_node        list

#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 s == p;
}

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

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

static inline struct mem_cgroup *memcg_from_slab_page(struct page *page)
{
        return NULL;
}

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)
{
}

static inline void memcg_link_cache(struct kmem_cache *s,
                                    struct mem_cgroup *memcg)
{
}

#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 int charge_slab_page(struct page *page,
                                            gfp_t gfp, int order,
                                            struct kmem_cache *s)
{
        if (is_root_cache(s)) {
                mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
                                    1 << order);
                return 0;
        }

        return memcg_charge_slab(page, gfp, order, s);
}

static __always_inline void uncharge_slab_page(struct page *page, int order,
                                               struct kmem_cache *s)
{
        if (is_root_cache(s)) {
                mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
                                    -(1 << order));
                return;
        }

        memcg_uncharge_slab(page, order, s);
}

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

        /*
         * 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() &&
            !IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
            !unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
                return s;

        cachep = virt_to_cache(x);
        WARN_ONCE(cachep && !slab_equal_or_root(cachep, s),
                  "%s: Wrong slab cache. %s but object is from %s\n",
                  __func__, s->name, cachep->name);
        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,
                                                     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_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++) {
                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);
        }

        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 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);
void *memcg_slab_start(struct seq_file *m, loff_t *pos);
void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos);
void memcg_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 */