Linux 4.6-rc6

[cris-mirror.git] / include / linux / memcontrol.h

/* memcontrol.h - Memory Controller
 *
 * Copyright IBM Corporation, 2007
 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
 *
 * Copyright 2007 OpenVZ SWsoft Inc
 * Author: Pavel Emelianov <xemul@openvz.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#ifndef _LINUX_MEMCONTROL_H
#define _LINUX_MEMCONTROL_H
#include <linux/cgroup.h>
#include <linux/vm_event_item.h>
#include <linux/hardirq.h>
#include <linux/jump_label.h>
#include <linux/page_counter.h>
#include <linux/vmpressure.h>
#include <linux/eventfd.h>
#include <linux/mmzone.h>
#include <linux/writeback.h>
#include <linux/page-flags.h>

struct mem_cgroup;
struct page;
struct mm_struct;
struct kmem_cache;

/*
 * The corresponding mem_cgroup_stat_names is defined in mm/memcontrol.c,
 * These two lists should keep in accord with each other.
 */
enum mem_cgroup_stat_index {
        /*
         * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
         */
        MEM_CGROUP_STAT_CACHE,          /* # of pages charged as cache */
        MEM_CGROUP_STAT_RSS,            /* # of pages charged as anon rss */
        MEM_CGROUP_STAT_RSS_HUGE,       /* # of pages charged as anon huge */
        MEM_CGROUP_STAT_FILE_MAPPED,    /* # of pages charged as file rss */
        MEM_CGROUP_STAT_DIRTY,          /* # of dirty pages in page cache */
        MEM_CGROUP_STAT_WRITEBACK,      /* # of pages under writeback */
        MEM_CGROUP_STAT_SWAP,           /* # of pages, swapped out */
        MEM_CGROUP_STAT_NSTATS,
        /* default hierarchy stats */
        MEMCG_KERNEL_STACK = MEM_CGROUP_STAT_NSTATS,
        MEMCG_SLAB_RECLAIMABLE,
        MEMCG_SLAB_UNRECLAIMABLE,
        MEMCG_SOCK,
        MEMCG_NR_STAT,
};

struct mem_cgroup_reclaim_cookie {
        struct zone *zone;
        int priority;
        unsigned int generation;
};

enum mem_cgroup_events_index {
        MEM_CGROUP_EVENTS_PGPGIN,       /* # of pages paged in */
        MEM_CGROUP_EVENTS_PGPGOUT,      /* # of pages paged out */
        MEM_CGROUP_EVENTS_PGFAULT,      /* # of page-faults */
        MEM_CGROUP_EVENTS_PGMAJFAULT,   /* # of major page-faults */
        MEM_CGROUP_EVENTS_NSTATS,
        /* default hierarchy events */
        MEMCG_LOW = MEM_CGROUP_EVENTS_NSTATS,
        MEMCG_HIGH,
        MEMCG_MAX,
        MEMCG_OOM,
        MEMCG_NR_EVENTS,
};

/*
 * Per memcg event counter is incremented at every pagein/pageout. With THP,
 * it will be incremated by the number of pages. This counter is used for
 * for trigger some periodic events. This is straightforward and better
 * than using jiffies etc. to handle periodic memcg event.
 */
enum mem_cgroup_events_target {
        MEM_CGROUP_TARGET_THRESH,
        MEM_CGROUP_TARGET_SOFTLIMIT,
        MEM_CGROUP_TARGET_NUMAINFO,
        MEM_CGROUP_NTARGETS,
};

#ifdef CONFIG_MEMCG

#define MEM_CGROUP_ID_SHIFT     16
#define MEM_CGROUP_ID_MAX       USHRT_MAX

struct mem_cgroup_stat_cpu {
        long count[MEMCG_NR_STAT];
        unsigned long events[MEMCG_NR_EVENTS];
        unsigned long nr_page_events;
        unsigned long targets[MEM_CGROUP_NTARGETS];
};

struct mem_cgroup_reclaim_iter {
        struct mem_cgroup *position;
        /* scan generation, increased every round-trip */
        unsigned int generation;
};

/*
 * per-zone information in memory controller.
 */
struct mem_cgroup_per_zone {
        struct lruvec           lruvec;
        unsigned long           lru_size[NR_LRU_LISTS];

        struct mem_cgroup_reclaim_iter  iter[DEF_PRIORITY + 1];

        struct rb_node          tree_node;      /* RB tree node */
        unsigned long           usage_in_excess;/* Set to the value by which */
                                                /* the soft limit is exceeded*/
        bool                    on_tree;
        struct mem_cgroup       *memcg;         /* Back pointer, we cannot */
                                                /* use container_of        */
};

struct mem_cgroup_per_node {
        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
};

struct mem_cgroup_threshold {
        struct eventfd_ctx *eventfd;
        unsigned long threshold;
};

/* For threshold */
struct mem_cgroup_threshold_ary {
        /* An array index points to threshold just below or equal to usage. */
        int current_threshold;
        /* Size of entries[] */
        unsigned int size;
        /* Array of thresholds */
        struct mem_cgroup_threshold entries[0];
};

struct mem_cgroup_thresholds {
        /* Primary thresholds array */
        struct mem_cgroup_threshold_ary *primary;
        /*
         * Spare threshold array.
         * This is needed to make mem_cgroup_unregister_event() "never fail".
         * It must be able to store at least primary->size - 1 entries.
         */
        struct mem_cgroup_threshold_ary *spare;
};

enum memcg_kmem_state {
        KMEM_NONE,
        KMEM_ALLOCATED,
        KMEM_ONLINE,
};

/*
 * The memory controller data structure. The memory controller controls both
 * page cache and RSS per cgroup. We would eventually like to provide
 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
 * to help the administrator determine what knobs to tune.
 */
struct mem_cgroup {
        struct cgroup_subsys_state css;

        /* Accounted resources */
        struct page_counter memory;
        struct page_counter swap;

        /* Legacy consumer-oriented counters */
        struct page_counter memsw;
        struct page_counter kmem;
        struct page_counter tcpmem;

        /* Normal memory consumption range */
        unsigned long low;
        unsigned long high;

        /* Range enforcement for interrupt charges */
        struct work_struct high_work;

        unsigned long soft_limit;

        /* vmpressure notifications */
        struct vmpressure vmpressure;

        /*
         * Should the accounting and control be hierarchical, per subtree?
         */
        bool use_hierarchy;

        /* protected by memcg_oom_lock */
        bool            oom_lock;
        int             under_oom;

        int     swappiness;
        /* OOM-Killer disable */
        int             oom_kill_disable;

        /* handle for "memory.events" */
        struct cgroup_file events_file;

        /* protect arrays of thresholds */
        struct mutex thresholds_lock;

        /* thresholds for memory usage. RCU-protected */
        struct mem_cgroup_thresholds thresholds;

        /* thresholds for mem+swap usage. RCU-protected */
        struct mem_cgroup_thresholds memsw_thresholds;

        /* For oom notifier event fd */
        struct list_head oom_notify;

        /*
         * Should we move charges of a task when a task is moved into this
         * mem_cgroup ? And what type of charges should we move ?
         */
        unsigned long move_charge_at_immigrate;
        /*
         * set > 0 if pages under this cgroup are moving to other cgroup.
         */
        atomic_t                moving_account;
        /* taken only while moving_account > 0 */
        spinlock_t              move_lock;
        struct task_struct      *move_lock_task;
        unsigned long           move_lock_flags;
        /*
         * percpu counter.
         */
        struct mem_cgroup_stat_cpu __percpu *stat;

        unsigned long           socket_pressure;

        /* Legacy tcp memory accounting */
        bool                    tcpmem_active;
        int                     tcpmem_pressure;

#ifndef CONFIG_SLOB
        /* Index in the kmem_cache->memcg_params.memcg_caches array */
        int kmemcg_id;
        enum memcg_kmem_state kmem_state;
#endif

        int last_scanned_node;
#if MAX_NUMNODES > 1
        nodemask_t      scan_nodes;
        atomic_t        numainfo_events;
        atomic_t        numainfo_updating;
#endif

#ifdef CONFIG_CGROUP_WRITEBACK
        struct list_head cgwb_list;
        struct wb_domain cgwb_domain;
#endif

        /* List of events which userspace want to receive */
        struct list_head event_list;
        spinlock_t event_list_lock;

        struct mem_cgroup_per_node *nodeinfo[0];
        /* WARNING: nodeinfo must be the last member here */
};

extern struct mem_cgroup *root_mem_cgroup;

static inline bool mem_cgroup_disabled(void)
{
        return !cgroup_subsys_enabled(memory_cgrp_subsys);
}

/**
 * mem_cgroup_events - count memory events against a cgroup
 * @memcg: the memory cgroup
 * @idx: the event index
 * @nr: the number of events to account for
 */
static inline void mem_cgroup_events(struct mem_cgroup *memcg,
                       enum mem_cgroup_events_index idx,
                       unsigned int nr)
{
        this_cpu_add(memcg->stat->events[idx], nr);
        cgroup_file_notify(&memcg->events_file);
}

bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg);

int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
                          gfp_t gfp_mask, struct mem_cgroup **memcgp,
                          bool compound);
void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
                              bool lrucare, bool compound);
void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg,
                bool compound);
void mem_cgroup_uncharge(struct page *page);
void mem_cgroup_uncharge_list(struct list_head *page_list);

void mem_cgroup_migrate(struct page *oldpage, struct page *newpage);

struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);

bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);

static inline
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
        return css ? container_of(css, struct mem_cgroup, css) : NULL;
}

#define mem_cgroup_from_counter(counter, member)        \
        container_of(counter, struct mem_cgroup, member)

struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
                                   struct mem_cgroup *,
                                   struct mem_cgroup_reclaim_cookie *);
void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);

static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
{
        if (mem_cgroup_disabled())
                return 0;

        return memcg->css.id;
}

/**
 * mem_cgroup_from_id - look up a memcg from an id
 * @id: the id to look up
 *
 * Caller must hold rcu_read_lock() and use css_tryget() as necessary.
 */
static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
        struct cgroup_subsys_state *css;

        css = css_from_id(id, &memory_cgrp_subsys);
        return mem_cgroup_from_css(css);
}

/**
 * parent_mem_cgroup - find the accounting parent of a memcg
 * @memcg: memcg whose parent to find
 *
 * Returns the parent memcg, or NULL if this is the root or the memory
 * controller is in legacy no-hierarchy mode.
 */
static inline struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
{
        if (!memcg->memory.parent)
                return NULL;
        return mem_cgroup_from_counter(memcg->memory.parent, memory);
}

static inline bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
                              struct mem_cgroup *root)
{
        if (root == memcg)
                return true;
        if (!root->use_hierarchy)
                return false;
        return cgroup_is_descendant(memcg->css.cgroup, root->css.cgroup);
}

static inline bool mm_match_cgroup(struct mm_struct *mm,
                                   struct mem_cgroup *memcg)
{
        struct mem_cgroup *task_memcg;
        bool match = false;

        rcu_read_lock();
        task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
        if (task_memcg)
                match = mem_cgroup_is_descendant(task_memcg, memcg);
        rcu_read_unlock();
        return match;
}

struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page);
ino_t page_cgroup_ino(struct page *page);

static inline bool mem_cgroup_online(struct mem_cgroup *memcg)
{
        if (mem_cgroup_disabled())
                return true;
        return !!(memcg->css.flags & CSS_ONLINE);
}

/*
 * For memory reclaim.
 */
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);

void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
                int nr_pages);

unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
                                           int nid, unsigned int lru_mask);

static inline
unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
{
        struct mem_cgroup_per_zone *mz;

        mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
        return mz->lru_size[lru];
}

static inline bool mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
{
        unsigned long inactive_ratio;
        unsigned long inactive;
        unsigned long active;
        unsigned long gb;

        inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_ANON);
        active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_ANON);

        gb = (inactive + active) >> (30 - PAGE_SHIFT);
        if (gb)
                inactive_ratio = int_sqrt(10 * gb);
        else
                inactive_ratio = 1;

        return inactive * inactive_ratio < active;
}

void mem_cgroup_handle_over_high(void);

void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
                                struct task_struct *p);

static inline void mem_cgroup_oom_enable(void)
{
        WARN_ON(current->memcg_may_oom);
        current->memcg_may_oom = 1;
}

static inline void mem_cgroup_oom_disable(void)
{
        WARN_ON(!current->memcg_may_oom);
        current->memcg_may_oom = 0;
}

static inline bool task_in_memcg_oom(struct task_struct *p)
{
        return p->memcg_in_oom;
}

bool mem_cgroup_oom_synchronize(bool wait);

#ifdef CONFIG_MEMCG_SWAP
extern int do_swap_account;
#endif

void lock_page_memcg(struct page *page);
void unlock_page_memcg(struct page *page);

/**
 * mem_cgroup_update_page_stat - update page state statistics
 * @page: the page
 * @idx: page state item to account
 * @val: number of pages (positive or negative)
 *
 * The @page must be locked or the caller must use lock_page_memcg()
 * to prevent double accounting when the page is concurrently being
 * moved to another memcg:
 *
 *   lock_page(page) or lock_page_memcg(page)
 *   if (TestClearPageState(page))
 *     mem_cgroup_update_page_stat(page, state, -1);
 *   unlock_page(page) or unlock_page_memcg(page)
 */
static inline void mem_cgroup_update_page_stat(struct page *page,
                                 enum mem_cgroup_stat_index idx, int val)
{
        VM_BUG_ON(!(rcu_read_lock_held() || PageLocked(page)));

        if (page->mem_cgroup)
                this_cpu_add(page->mem_cgroup->stat->count[idx], val);
}

static inline void mem_cgroup_inc_page_stat(struct page *page,
                                            enum mem_cgroup_stat_index idx)
{
        mem_cgroup_update_page_stat(page, idx, 1);
}

static inline void mem_cgroup_dec_page_stat(struct page *page,
                                            enum mem_cgroup_stat_index idx)
{
        mem_cgroup_update_page_stat(page, idx, -1);
}

unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
                                                gfp_t gfp_mask,
                                                unsigned long *total_scanned);

static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
                                             enum vm_event_item idx)
{
        struct mem_cgroup *memcg;

        if (mem_cgroup_disabled())
                return;

        rcu_read_lock();
        memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
        if (unlikely(!memcg))
                goto out;

        switch (idx) {
        case PGFAULT:
                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
                break;
        case PGMAJFAULT:
                this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
                break;
        default:
                BUG();
        }
out:
        rcu_read_unlock();
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void mem_cgroup_split_huge_fixup(struct page *head);
#endif

#else /* CONFIG_MEMCG */

#define MEM_CGROUP_ID_SHIFT     0
#define MEM_CGROUP_ID_MAX       0

struct mem_cgroup;

static inline bool mem_cgroup_disabled(void)
{
        return true;
}

static inline void mem_cgroup_events(struct mem_cgroup *memcg,
                                     enum mem_cgroup_events_index idx,
                                     unsigned int nr)
{
}

static inline bool mem_cgroup_low(struct mem_cgroup *root,
                                  struct mem_cgroup *memcg)
{
        return false;
}

static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
                                        gfp_t gfp_mask,
                                        struct mem_cgroup **memcgp,
                                        bool compound)
{
        *memcgp = NULL;
        return 0;
}

static inline void mem_cgroup_commit_charge(struct page *page,
                                            struct mem_cgroup *memcg,
                                            bool lrucare, bool compound)
{
}

static inline void mem_cgroup_cancel_charge(struct page *page,
                                            struct mem_cgroup *memcg,
                                            bool compound)
{
}

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

static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
{
}

static inline void mem_cgroup_migrate(struct page *old, struct page *new)
{
}

static inline struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
                                                    struct mem_cgroup *memcg)
{
        return &zone->lruvec;
}

static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
                                                    struct zone *zone)
{
        return &zone->lruvec;
}

static inline bool mm_match_cgroup(struct mm_struct *mm,
                struct mem_cgroup *memcg)
{
        return true;
}

static inline bool task_in_mem_cgroup(struct task_struct *task,
                                      const struct mem_cgroup *memcg)
{
        return true;
}

static inline struct mem_cgroup *
mem_cgroup_iter(struct mem_cgroup *root,
                struct mem_cgroup *prev,
                struct mem_cgroup_reclaim_cookie *reclaim)
{
        return NULL;
}

static inline void mem_cgroup_iter_break(struct mem_cgroup *root,
                                         struct mem_cgroup *prev)
{
}

static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
{
        return 0;
}

static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
{
        WARN_ON_ONCE(id);
        /* XXX: This should always return root_mem_cgroup */
        return NULL;
}

static inline bool mem_cgroup_online(struct mem_cgroup *memcg)
{
        return true;
}

static inline bool
mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
{
        return true;
}

static inline unsigned long
mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
{
        return 0;
}

static inline void
mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
                              int increment)
{
}

static inline unsigned long
mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
                             int nid, unsigned int lru_mask)
{
        return 0;
}

static inline void
mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
{
}

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

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

static inline void mem_cgroup_handle_over_high(void)
{
}

static inline void mem_cgroup_oom_enable(void)
{
}

static inline void mem_cgroup_oom_disable(void)
{
}

static inline bool task_in_memcg_oom(struct task_struct *p)
{
        return false;
}

static inline bool mem_cgroup_oom_synchronize(bool wait)
{
        return false;
}

static inline void mem_cgroup_inc_page_stat(struct page *page,
                                            enum mem_cgroup_stat_index idx)
{
}

static inline void mem_cgroup_dec_page_stat(struct page *page,
                                            enum mem_cgroup_stat_index idx)
{
}

static inline
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
                                            gfp_t gfp_mask,
                                            unsigned long *total_scanned)
{
        return 0;
}

static inline void mem_cgroup_split_huge_fixup(struct page *head)
{
}

static inline
void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
{
}
#endif /* CONFIG_MEMCG */

#ifdef CONFIG_CGROUP_WRITEBACK

struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg);
struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
                         unsigned long *pheadroom, unsigned long *pdirty,
                         unsigned long *pwriteback);

#else   /* CONFIG_CGROUP_WRITEBACK */

static inline struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
{
        return NULL;
}

static inline void mem_cgroup_wb_stats(struct bdi_writeback *wb,
                                       unsigned long *pfilepages,
                                       unsigned long *pheadroom,
                                       unsigned long *pdirty,
                                       unsigned long *pwriteback)
{
}

#endif  /* CONFIG_CGROUP_WRITEBACK */

struct sock;
void sock_update_memcg(struct sock *sk);
void sock_release_memcg(struct sock *sk);
bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
#ifdef CONFIG_MEMCG
extern struct static_key_false memcg_sockets_enabled_key;
#define mem_cgroup_sockets_enabled static_branch_unlikely(&memcg_sockets_enabled_key)
static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
{
        if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_pressure)
                return true;
        do {
                if (time_before(jiffies, memcg->socket_pressure))
                        return true;
        } while ((memcg = parent_mem_cgroup(memcg)));
        return false;
}
#else
#define mem_cgroup_sockets_enabled 0
static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
{
        return false;
}
#endif

#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
extern struct static_key_false memcg_kmem_enabled_key;

extern int memcg_nr_cache_ids;
void memcg_get_cache_ids(void);
void memcg_put_cache_ids(void);

/*
 * Helper macro to loop through all memcg-specific caches. Callers must still
 * check if the cache is valid (it is either valid or NULL).
 * the slab_mutex must be held when looping through those caches
 */
#define for_each_memcg_cache_index(_idx)        \
        for ((_idx) = 0; (_idx) < memcg_nr_cache_ids; (_idx)++)

static inline bool memcg_kmem_enabled(void)
{
        return static_branch_unlikely(&memcg_kmem_enabled_key);
}

/*
 * In general, we'll do everything in our power to not incur in any overhead
 * for non-memcg users for the kmem functions. Not even a function call, if we
 * can avoid it.
 *
 * Therefore, we'll inline all those functions so that in the best case, we'll
 * see that kmemcg is off for everybody and proceed quickly.  If it is on,
 * we'll still do most of the flag checking inline. We check a lot of
 * conditions, but because they are pretty simple, they are expected to be
 * fast.
 */
int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
                              struct mem_cgroup *memcg);
int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order);
void __memcg_kmem_uncharge(struct page *page, int order);

/*
 * helper for accessing a memcg's index. It will be used as an index in the
 * child cache array in kmem_cache, and also to derive its name. This function
 * will return -1 when this is not a kmem-limited memcg.
 */
static inline int memcg_cache_id(struct mem_cgroup *memcg)
{
        return memcg ? memcg->kmemcg_id : -1;
}

struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
void __memcg_kmem_put_cache(struct kmem_cache *cachep);

static inline bool __memcg_kmem_bypass(void)
{
        if (!memcg_kmem_enabled())
                return true;
        if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
                return true;
        return false;
}

/**
 * memcg_kmem_charge: charge a kmem page
 * @page: page to charge
 * @gfp: reclaim mode
 * @order: allocation order
 *
 * Returns 0 on success, an error code on failure.
 */
static __always_inline int memcg_kmem_charge(struct page *page,
                                             gfp_t gfp, int order)
{
        if (__memcg_kmem_bypass())
                return 0;
        if (!(gfp & __GFP_ACCOUNT))
                return 0;
        return __memcg_kmem_charge(page, gfp, order);
}

/**
 * memcg_kmem_uncharge: uncharge a kmem page
 * @page: page to uncharge
 * @order: allocation order
 */
static __always_inline void memcg_kmem_uncharge(struct page *page, int order)
{
        if (memcg_kmem_enabled())
                __memcg_kmem_uncharge(page, order);
}

/**
 * memcg_kmem_get_cache: selects the correct per-memcg cache for allocation
 * @cachep: the original global kmem cache
 *
 * All memory allocated from a per-memcg cache is charged to the owner memcg.
 */
static __always_inline struct kmem_cache *
memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
        if (__memcg_kmem_bypass())
                return cachep;
        return __memcg_kmem_get_cache(cachep, gfp);
}

static __always_inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
        if (memcg_kmem_enabled())
                __memcg_kmem_put_cache(cachep);
}

/**
 * memcg_kmem_update_page_stat - update kmem page state statistics
 * @page: the page
 * @idx: page state item to account
 * @val: number of pages (positive or negative)
 */
static inline void memcg_kmem_update_page_stat(struct page *page,
                                enum mem_cgroup_stat_index idx, int val)
{
        if (memcg_kmem_enabled() && page->mem_cgroup)
                this_cpu_add(page->mem_cgroup->stat->count[idx], val);
}

#else
#define for_each_memcg_cache_index(_idx)        \
        for (; NULL; )

static inline bool memcg_kmem_enabled(void)
{
        return false;
}

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

static inline void memcg_kmem_uncharge(struct page *page, int order)
{
}

static inline int memcg_cache_id(struct mem_cgroup *memcg)
{
        return -1;
}

static inline void memcg_get_cache_ids(void)
{
}

static inline void memcg_put_cache_ids(void)
{
}

static inline struct kmem_cache *
memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
        return cachep;
}

static inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
}

static inline void memcg_kmem_update_page_stat(struct page *page,
                                enum mem_cgroup_stat_index idx, int val)
{
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */

#endif /* _LINUX_MEMCONTROL_H */