/* SPDX-License-Identifier: GPL-2.0-or-later */
/* 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>
 */

#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/mm.h>
#include <linux/vmstat.h>
#include <linux/writeback.h>
#include <linux/page-flags.h>

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

/* Cgroup-specific page state, on top of universal node page state */
enum memcg_stat_item {
        MEMCG_SWAP = NR_VM_NODE_STAT_ITEMS,
        MEMCG_SOCK,
        MEMCG_PERCPU_B,
        MEMCG_NR_STAT,
};

enum memcg_memory_event {
        MEMCG_LOW,
        MEMCG_HIGH,
        MEMCG_MAX,
        MEMCG_OOM,
        MEMCG_OOM_KILL,
        MEMCG_SWAP_HIGH,
        MEMCG_SWAP_MAX,
        MEMCG_SWAP_FAIL,
        MEMCG_NR_MEMORY_EVENTS,
};

struct mem_cgroup_reclaim_cookie {
        pg_data_t *pgdat;
        unsigned int generation;
};

#ifdef CONFIG_MEMCG

#define MEM_CGROUP_ID_SHIFT     16
#define MEM_CGROUP_ID_MAX       USHRT_MAX

struct mem_cgroup_id {
        int id;
        refcount_t ref;
};

/*
 * Per memcg event counter is incremented at every pagein/pageout. With THP,
 * it will be incremented by the number of pages. This counter is used
 * to 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_NTARGETS,
};

struct memcg_vmstats_percpu {
        long stat[MEMCG_NR_STAT];
        unsigned long events[NR_VM_EVENT_ITEMS];
        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;
};

struct lruvec_stat {
        long count[NR_VM_NODE_STAT_ITEMS];
};

/*
 * Bitmap of shrinker::id corresponding to memcg-aware shrinkers,
 * which have elements charged to this memcg.
 */
struct memcg_shrinker_map {
        struct rcu_head rcu;
        unsigned long map[];
};

/*
 * per-node information in memory controller.
 */
struct mem_cgroup_per_node {
        struct lruvec           lruvec;

        /* Legacy local VM stats */
        struct lruvec_stat __percpu *lruvec_stat_local;

        /* Subtree VM stats (batched updates) */
        struct lruvec_stat __percpu *lruvec_stat_cpu;
        atomic_long_t           lruvec_stat[NR_VM_NODE_STAT_ITEMS];

        unsigned long           lru_zone_size[MAX_NR_ZONES][NR_LRU_LISTS];

        struct mem_cgroup_reclaim_iter  iter;

        struct memcg_shrinker_map __rcu *shrinker_map;

        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_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[];
};

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,
};

#if defined(CONFIG_SMP)
struct memcg_padding {
        char x[0];
} ____cacheline_internodealigned_in_smp;
#define MEMCG_PADDING(name)      struct memcg_padding name;
#else
#define MEMCG_PADDING(name)
#endif

/*
 * Remember four most recent foreign writebacks with dirty pages in this
 * cgroup.  Inode sharing is expected to be uncommon and, even if we miss
 * one in a given round, we're likely to catch it later if it keeps
 * foreign-dirtying, so a fairly low count should be enough.
 *
 * See mem_cgroup_track_foreign_dirty_slowpath() for details.
 */
#define MEMCG_CGWB_FRN_CNT      4

struct memcg_cgwb_frn {
        u64 bdi_id;                     /* bdi->id of the foreign inode */
        int memcg_id;                   /* memcg->css.id of foreign inode */
        u64 at;                         /* jiffies_64 at the time of dirtying */
        struct wb_completion done;      /* tracks in-flight foreign writebacks */
};

/*
 * Bucket for arbitrarily byte-sized objects charged to a memory
 * cgroup. The bucket can be reparented in one piece when the cgroup
 * is destroyed, without having to round up the individual references
 * of all live memory objects in the wild.
 */
struct obj_cgroup {
        struct percpu_ref refcnt;
        struct mem_cgroup *memcg;
        atomic_t nr_charged_bytes;
        union {
                struct list_head list;
                struct rcu_head rcu;
        };
};

/*
 * 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;

        /* Private memcg ID. Used to ID objects that outlive the cgroup */
        struct mem_cgroup_id id;

        /* Accounted resources */
        struct page_counter memory;             /* Both v1 & v2 */

        union {
                struct page_counter swap;       /* v2 only */
                struct page_counter memsw;      /* v1 only */
        };

        /* Legacy consumer-oriented counters */
        struct page_counter kmem;               /* v1 only */
        struct page_counter tcpmem;             /* v1 only */

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

        unsigned long soft_limit;

        /* vmpressure notifications */
        struct vmpressure vmpressure;

        /*
         * Should the OOM killer kill all belonging tasks, had it kill one?
         */
        bool oom_group;

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

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

        /* memory.events and memory.events.local */
        struct cgroup_file events_file;
        struct cgroup_file events_local_file;

        /* handle for "memory.swap.events" */
        struct cgroup_file swap_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;
        /* taken only while moving_account > 0 */
        spinlock_t              move_lock;
        unsigned long           move_lock_flags;

        MEMCG_PADDING(_pad1_);

        atomic_long_t           vmstats[MEMCG_NR_STAT];
        atomic_long_t           vmevents[NR_VM_EVENT_ITEMS];

        /* memory.events */
        atomic_long_t           memory_events[MEMCG_NR_MEMORY_EVENTS];
        atomic_long_t           memory_events_local[MEMCG_NR_MEMORY_EVENTS];

        unsigned long           socket_pressure;

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

#ifdef CONFIG_MEMCG_KMEM
        int kmemcg_id;
        enum memcg_kmem_state kmem_state;
        struct obj_cgroup __rcu *objcg;
        struct list_head objcg_list; /* list of inherited objcgs */
#endif

        MEMCG_PADDING(_pad2_);

        /*
         * set > 0 if pages under this cgroup are moving to other cgroup.
         */
        atomic_t                moving_account;
        struct task_struct      *move_lock_task;

        /* Legacy local VM stats and events */
        struct memcg_vmstats_percpu __percpu *vmstats_local;

        /* Subtree VM stats and events (batched updates) */
        struct memcg_vmstats_percpu __percpu *vmstats_percpu;

#ifdef CONFIG_CGROUP_WRITEBACK
        struct list_head cgwb_list;
        struct wb_domain cgwb_domain;
        struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT];
#endif

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

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        struct deferred_split deferred_split_queue;
#endif

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

/*
 * size of first charge trial. "32" comes from vmscan.c's magic value.
 * TODO: maybe necessary to use big numbers in big irons.
 */
#define MEMCG_CHARGE_BATCH 32U

extern struct mem_cgroup *root_mem_cgroup;

enum page_memcg_data_flags {
        /* page->memcg_data is a pointer to an objcgs vector */
        MEMCG_DATA_OBJCGS = (1UL << 0),
        /* page has been accounted as a non-slab kernel page */
        MEMCG_DATA_KMEM = (1UL << 1),
        /* the next bit after the last actual flag */
        __NR_MEMCG_DATA_FLAGS  = (1UL << 2),
};

#define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1)

/*
 * page_memcg - get the memory cgroup associated with a page
 * @page: a pointer to the page struct
 *
 * Returns a pointer to the memory cgroup associated with the page,
 * or NULL. This function assumes that the page is known to have a
 * proper memory cgroup pointer. It's not safe to call this function
 * against some type of pages, e.g. slab pages or ex-slab pages.
 *
 * Any of the following ensures page and memcg binding stability:
 * - the page lock
 * - LRU isolation
 * - lock_page_memcg()
 * - exclusive reference
 */
static inline struct mem_cgroup *page_memcg(struct page *page)
{
        unsigned long memcg_data = page->memcg_data;

        VM_BUG_ON_PAGE(PageSlab(page), page);
        VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page);

        return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
}

/*
 * page_memcg_rcu - locklessly get the memory cgroup associated with a page
 * @page: a pointer to the page struct
 *
 * Returns a pointer to the memory cgroup associated with the page,
 * or NULL. This function assumes that the page is known to have a
 * proper memory cgroup pointer. It's not safe to call this function
 * against some type of pages, e.g. slab pages or ex-slab pages.
 */
static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
{
        VM_BUG_ON_PAGE(PageSlab(page), page);
        WARN_ON_ONCE(!rcu_read_lock_held());

        return (struct mem_cgroup *)(READ_ONCE(page->memcg_data) &
                                     ~MEMCG_DATA_FLAGS_MASK);
}

/*
 * page_memcg_check - get the memory cgroup associated with a page
 * @page: a pointer to the page struct
 *
 * Returns a pointer to the memory cgroup associated with the page,
 * or NULL. This function unlike page_memcg() can take any  page
 * as an argument. It has to be used in cases when it's not known if a page
 * has an associated memory cgroup pointer or an object cgroups vector.
 *
 * Any of the following ensures page and memcg binding stability:
 * - the page lock
 * - LRU isolation
 * - lock_page_memcg()
 * - exclusive reference
 */
static inline struct mem_cgroup *page_memcg_check(struct page *page)
{
        /*
         * Because page->memcg_data might be changed asynchronously
         * for slab pages, READ_ONCE() should be used here.
         */
        unsigned long memcg_data = READ_ONCE(page->memcg_data);

        if (memcg_data & MEMCG_DATA_OBJCGS)
                return NULL;

        return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
}

/*
 * PageMemcgKmem - check if the page has MemcgKmem flag set
 * @page: a pointer to the page struct
 *
 * Checks if the page has MemcgKmem flag set. The caller must ensure that
 * the page has an associated memory cgroup. It's not safe to call this function
 * against some types of pages, e.g. slab pages.
 */
static inline bool PageMemcgKmem(struct page *page)
{
        VM_BUG_ON_PAGE(page->memcg_data & MEMCG_DATA_OBJCGS, page);
        return page->memcg_data & MEMCG_DATA_KMEM;
}

#ifdef CONFIG_MEMCG_KMEM
/*
 * page_objcgs - get the object cgroups vector associated with a page
 * @page: a pointer to the page struct
 *
 * Returns a pointer to the object cgroups vector associated with the page,
 * or NULL. This function assumes that the page is known to have an
 * associated object cgroups vector. It's not safe to call this function
 * against pages, which might have an associated memory cgroup: e.g.
 * kernel stack pages.
 */
static inline struct obj_cgroup **page_objcgs(struct page *page)
{
        unsigned long memcg_data = READ_ONCE(page->memcg_data);

        VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), page);
        VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page);

        return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
}

/*
 * page_objcgs_check - get the object cgroups vector associated with a page
 * @page: a pointer to the page struct
 *
 * Returns a pointer to the object cgroups vector associated with the page,
 * or NULL. This function is safe to use if the page can be directly associated
 * with a memory cgroup.
 */
static inline struct obj_cgroup **page_objcgs_check(struct page *page)
{
        unsigned long memcg_data = READ_ONCE(page->memcg_data);

        if (!memcg_data || !(memcg_data & MEMCG_DATA_OBJCGS))
                return NULL;

        VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page);

        return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
}

/*
 * set_page_objcgs - associate a page with a object cgroups vector
 * @page: a pointer to the page struct
 * @objcgs: a pointer to the object cgroups vector
 *
 * Atomically associates a page with a vector of object cgroups.
 */
static inline bool set_page_objcgs(struct page *page,
                                        struct obj_cgroup **objcgs)
{
        return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs |
                        MEMCG_DATA_OBJCGS);
}
#else
static inline struct obj_cgroup **page_objcgs(struct page *page)
{
        return NULL;
}

static inline struct obj_cgroup **page_objcgs_check(struct page *page)
{
        return NULL;
}

static inline bool set_page_objcgs(struct page *page,
                                        struct obj_cgroup **objcgs)
{
        return true;
}
#endif

static __always_inline bool memcg_stat_item_in_bytes(int idx)
{
        if (idx == MEMCG_PERCPU_B)
                return true;
        return vmstat_item_in_bytes(idx);
}

static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
{
        return (memcg == root_mem_cgroup);
}

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

static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root,
                                                  struct mem_cgroup *memcg,
                                                  bool in_low_reclaim)
{
        if (mem_cgroup_disabled())
                return 0;

        /*
         * There is no reclaim protection applied to a targeted reclaim.
         * We are special casing this specific case here because
         * mem_cgroup_protected calculation is not robust enough to keep
         * the protection invariant for calculated effective values for
         * parallel reclaimers with different reclaim target. This is
         * especially a problem for tail memcgs (as they have pages on LRU)
         * which would want to have effective values 0 for targeted reclaim
         * but a different value for external reclaim.
         *
         * Example
         * Let's have global and A's reclaim in parallel:
         *  |
         *  A (low=2G, usage = 3G, max = 3G, children_low_usage = 1.5G)
         *  |\
         *  | C (low = 1G, usage = 2.5G)
         *  B (low = 1G, usage = 0.5G)
         *
         * For the global reclaim
         * A.elow = A.low
         * B.elow = min(B.usage, B.low) because children_low_usage <= A.elow
         * C.elow = min(C.usage, C.low)
         *
         * With the effective values resetting we have A reclaim
         * A.elow = 0
         * B.elow = B.low
         * C.elow = C.low
         *
         * If the global reclaim races with A's reclaim then
         * B.elow = C.elow = 0 because children_low_usage > A.elow)
         * is possible and reclaiming B would be violating the protection.
         *
         */
        if (root == memcg)
                return 0;

        if (in_low_reclaim)
                return READ_ONCE(memcg->memory.emin);

        return max(READ_ONCE(memcg->memory.emin),
                   READ_ONCE(memcg->memory.elow));
}

void mem_cgroup_calculate_protection(struct mem_cgroup *root,
                                     struct mem_cgroup *memcg);

static inline bool mem_cgroup_supports_protection(struct mem_cgroup *memcg)
{
        /*
         * The root memcg doesn't account charges, and doesn't support
         * protection.
         */
        return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg);

}

static inline bool mem_cgroup_below_low(struct mem_cgroup *memcg)
{
        if (!mem_cgroup_supports_protection(memcg))
                return false;

        return READ_ONCE(memcg->memory.elow) >=
                page_counter_read(&memcg->memory);
}

static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg)
{
        if (!mem_cgroup_supports_protection(memcg))
                return false;

        return READ_ONCE(memcg->memory.emin) >=
                page_counter_read(&memcg->memory);
}

int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask);

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);

static struct mem_cgroup_per_node *
mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
{
        return memcg->nodeinfo[nid];
}

/**
 * mem_cgroup_lruvec - get the lru list vector for a memcg & node
 * @memcg: memcg of the wanted lruvec
 * @pgdat: pglist_data
 *
 * Returns the lru list vector holding pages for a given @memcg &
 * @pgdat combination. This can be the node lruvec, if the memory
 * controller is disabled.
 */
static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
                                               struct pglist_data *pgdat)
{
        struct mem_cgroup_per_node *mz;
        struct lruvec *lruvec;

        if (mem_cgroup_disabled()) {
                lruvec = &pgdat->__lruvec;
                goto out;
        }

        if (!memcg)
                memcg = root_mem_cgroup;

        mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
        lruvec = &mz->lruvec;
out:
        /*
         * Since a node can be onlined after the mem_cgroup was created,
         * we have to be prepared to initialize lruvec->pgdat here;
         * and if offlined then reonlined, we need to reinitialize it.
         */
        if (unlikely(lruvec->pgdat != pgdat))
                lruvec->pgdat = pgdat;
        return lruvec;
}

/**
 * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
 * @page: the page
 * @pgdat: pgdat of the page
 *
 * This function relies on page->mem_cgroup being stable.
 */
static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
                                                struct pglist_data *pgdat)
{
        struct mem_cgroup *memcg = page_memcg(page);

        VM_WARN_ON_ONCE_PAGE(!memcg && !mem_cgroup_disabled(), page);
        return mem_cgroup_lruvec(memcg, pgdat);
}

static inline bool lruvec_holds_page_lru_lock(struct page *page,
                                              struct lruvec *lruvec)
{
        pg_data_t *pgdat = page_pgdat(page);
        const struct mem_cgroup *memcg;
        struct mem_cgroup_per_node *mz;

        if (mem_cgroup_disabled())
                return lruvec == &pgdat->__lruvec;

        mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
        memcg = page_memcg(page) ? : root_mem_cgroup;

        return lruvec->pgdat == pgdat && mz->memcg == memcg;
}

struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);

struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);

struct mem_cgroup *get_mem_cgroup_from_page(struct page *page);

struct lruvec *lock_page_lruvec(struct page *page);
struct lruvec *lock_page_lruvec_irq(struct page *page);
struct lruvec *lock_page_lruvec_irqsave(struct page *page,
                                                unsigned long *flags);

#ifdef CONFIG_DEBUG_VM
void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page);
#else
static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
{
}
#endif

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

static inline bool obj_cgroup_tryget(struct obj_cgroup *objcg)
{
        return percpu_ref_tryget(&objcg->refcnt);
}

static inline void obj_cgroup_get(struct obj_cgroup *objcg)
{
        percpu_ref_get(&objcg->refcnt);
}

static inline void obj_cgroup_put(struct obj_cgroup *objcg)
{
        percpu_ref_put(&objcg->refcnt);
}

/*
 * After the initialization objcg->memcg is always pointing at
 * a valid memcg, but can be atomically swapped to the parent memcg.
 *
 * The caller must ensure that the returned memcg won't be released:
 * e.g. acquire the rcu_read_lock or css_set_lock.
 */
static inline struct mem_cgroup *obj_cgroup_memcg(struct obj_cgroup *objcg)
{
        return READ_ONCE(objcg->memcg);
}

static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
        if (memcg)
                css_put(&memcg->css);
}

#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 *);
int mem_cgroup_scan_tasks(struct mem_cgroup *,
                          int (*)(struct task_struct *, void *), void *);

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

        return memcg->id.id;
}
struct mem_cgroup *mem_cgroup_from_id(unsigned short id);

static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
{
        return mem_cgroup_from_css(seq_css(m));
}

static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec)
{
        struct mem_cgroup_per_node *mz;

        if (mem_cgroup_disabled())
                return NULL;

        mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
        return mz->memcg;
}

/**
 * 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;
        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 zid, int nr_pages);

static inline
unsigned long mem_cgroup_get_zone_lru_size(struct lruvec *lruvec,
                enum lru_list lru, int zone_idx)
{
        struct mem_cgroup_per_node *mz;

        mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
        return READ_ONCE(mz->lru_zone_size[zone_idx][lru]);
}

void mem_cgroup_handle_over_high(void);

unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg);

unsigned long mem_cgroup_size(struct mem_cgroup *memcg);

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

void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg);

static inline void mem_cgroup_enter_user_fault(void)
{
        WARN_ON(current->in_user_fault);
        current->in_user_fault = 1;
}

static inline void mem_cgroup_exit_user_fault(void)
{
        WARN_ON(!current->in_user_fault);
        current->in_user_fault = 0;
}

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

bool mem_cgroup_oom_synchronize(bool wait);
struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
                                            struct mem_cgroup *oom_domain);
void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);

#ifdef CONFIG_MEMCG_SWAP
extern bool cgroup_memory_noswap;
#endif

struct mem_cgroup *lock_page_memcg(struct page *page);
void __unlock_page_memcg(struct mem_cgroup *memcg);
void unlock_page_memcg(struct page *page);

/*
 * idx can be of type enum memcg_stat_item or node_stat_item.
 * Keep in sync with memcg_exact_page_state().
 */
static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx)
{
        long x = atomic_long_read(&memcg->vmstats[idx]);
#ifdef CONFIG_SMP
        if (x < 0)
                x = 0;
#endif
        return x;
}

/*
 * idx can be of type enum memcg_stat_item or node_stat_item.
 * Keep in sync with memcg_exact_page_state().
 */
static inline unsigned long memcg_page_state_local(struct mem_cgroup *memcg,
                                                   int idx)
{
        long x = 0;
        int cpu;

        for_each_possible_cpu(cpu)
                x += per_cpu(memcg->vmstats_local->stat[idx], cpu);
#ifdef CONFIG_SMP
        if (x < 0)
                x = 0;
#endif
        return x;
}

void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val);

/* idx can be of type enum memcg_stat_item or node_stat_item */
static inline void mod_memcg_state(struct mem_cgroup *memcg,
                                   int idx, int val)
{
        unsigned long flags;

        local_irq_save(flags);
        __mod_memcg_state(memcg, idx, val);
        local_irq_restore(flags);
}

static inline unsigned long lruvec_page_state(struct lruvec *lruvec,
                                              enum node_stat_item idx)
{
        struct mem_cgroup_per_node *pn;
        long x;

        if (mem_cgroup_disabled())
                return node_page_state(lruvec_pgdat(lruvec), idx);

        pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
        x = atomic_long_read(&pn->lruvec_stat[idx]);
#ifdef CONFIG_SMP
        if (x < 0)
                x = 0;
#endif
        return x;
}

static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec,
                                                    enum node_stat_item idx)
{
        struct mem_cgroup_per_node *pn;
        long x = 0;
        int cpu;

        if (mem_cgroup_disabled())
                return node_page_state(lruvec_pgdat(lruvec), idx);

        pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
        for_each_possible_cpu(cpu)
                x += per_cpu(pn->lruvec_stat_local->count[idx], cpu);
#ifdef CONFIG_SMP
        if (x < 0)
                x = 0;
#endif
        return x;
}

void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
                              int val);
void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val);

static inline void mod_lruvec_kmem_state(void *p, enum node_stat_item idx,
                                         int val)
{
        unsigned long flags;

        local_irq_save(flags);
        __mod_lruvec_kmem_state(p, idx, val);
        local_irq_restore(flags);
}

static inline void mod_memcg_lruvec_state(struct lruvec *lruvec,
                                          enum node_stat_item idx, int val)
{
        unsigned long flags;

        local_irq_save(flags);
        __mod_memcg_lruvec_state(lruvec, idx, val);
        local_irq_restore(flags);
}

unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
                                                gfp_t gfp_mask,
                                                unsigned long *total_scanned);

void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
                          unsigned long count);

static inline void count_memcg_events(struct mem_cgroup *memcg,

                                      enum vm_event_item idx,
                                      unsigned long count)
{
        unsigned long flags;

        local_irq_save(flags);
        __count_memcg_events(memcg, idx, count);
        local_irq_restore(flags);
}

static inline void count_memcg_page_event(struct page *page,
                                          enum vm_event_item idx)
{
        struct mem_cgroup *memcg = page_memcg(page);

        if (memcg)
                count_memcg_events(memcg, idx, 1);
}

static inline void count_memcg_event_mm(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 (likely(memcg))
                count_memcg_events(memcg, idx, 1);
        rcu_read_unlock();
}

static inline void memcg_memory_event(struct mem_cgroup *memcg,
                                      enum memcg_memory_event event)
{
        bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
                          event == MEMCG_SWAP_FAIL;

        atomic_long_inc(&memcg->memory_events_local[event]);
        if (!swap_event)
                cgroup_file_notify(&memcg->events_local_file);

        do {
                atomic_long_inc(&memcg->memory_events[event]);
                if (swap_event)
                        cgroup_file_notify(&memcg->swap_events_file);
                else
                        cgroup_file_notify(&memcg->events_file);

                if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
                        break;
                if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
                        break;
        } while ((memcg = parent_mem_cgroup(memcg)) &&
                 !mem_cgroup_is_root(memcg));
}

static inline void memcg_memory_event_mm(struct mm_struct *mm,
                                         enum memcg_memory_event event)
{
        struct mem_cgroup *memcg;

        if (mem_cgroup_disabled())
                return;

        rcu_read_lock();
        memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
        if (likely(memcg))
                memcg_memory_event(memcg, event);
        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 struct mem_cgroup *page_memcg(struct page *page)
{
        return NULL;
}

static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
{
        WARN_ON_ONCE(!rcu_read_lock_held());
        return NULL;
}

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

static inline bool PageMemcgKmem(struct page *page)
{
        return false;
}

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

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

static inline void memcg_memory_event(struct mem_cgroup *memcg,
                                      enum memcg_memory_event event)
{
}

static inline void memcg_memory_event_mm(struct mm_struct *mm,
                                         enum memcg_memory_event event)
{
}

static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root,
                                                  struct mem_cgroup *memcg,
                                                  bool in_low_reclaim)
{
        return 0;
}

static inline void mem_cgroup_calculate_protection(struct mem_cgroup *root,
                                                   struct mem_cgroup *memcg)
{
}

static inline bool mem_cgroup_below_low(struct mem_cgroup *memcg)
{
        return false;
}

static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg)
{
        return false;
}

static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
                                    gfp_t gfp_mask)
{
        return 0;
}

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_lruvec(struct mem_cgroup *memcg,
                                               struct pglist_data *pgdat)
{
        return &pgdat->__lruvec;
}

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

static inline bool lruvec_holds_page_lru_lock(struct page *page,
                                              struct lruvec *lruvec)
{
        pg_data_t *pgdat = page_pgdat(page);

        return lruvec == &pgdat->__lruvec;
}

static inline struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
{
        return NULL;
}

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

static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
        return NULL;
}

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

static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
}

static inline struct lruvec *lock_page_lruvec(struct page *page)
{
        struct pglist_data *pgdat = page_pgdat(page);

        spin_lock(&pgdat->__lruvec.lru_lock);
        return &pgdat->__lruvec;
}

static inline struct lruvec *lock_page_lruvec_irq(struct page *page)
{
        struct pglist_data *pgdat = page_pgdat(page);

        spin_lock_irq(&pgdat->__lruvec.lru_lock);
        return &pgdat->__lruvec;
}

static inline struct lruvec *lock_page_lruvec_irqsave(struct page *page,
                unsigned long *flagsp)
{
        struct pglist_data *pgdat = page_pgdat(page);

        spin_lock_irqsave(&pgdat->__lruvec.lru_lock, *flagsp);
        return &pgdat->__lruvec;
}

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 int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
                int (*fn)(struct task_struct *, void *), void *arg)
{
        return 0;
}

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 struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
{
        return NULL;
}

static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec)
{
        return NULL;
}

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

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

static inline unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
{
        return 0;
}

static inline unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
{
        return 0;
}

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

static inline void
mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
{
}

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

static inline void __unlock_page_memcg(struct mem_cgroup *memcg)
{
}

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

static inline void mem_cgroup_handle_over_high(void)
{
}

static inline void mem_cgroup_enter_user_fault(void)
{
}

static inline void mem_cgroup_exit_user_fault(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 struct mem_cgroup *mem_cgroup_get_oom_group(
        struct task_struct *victim, struct mem_cgroup *oom_domain)
{
        return NULL;
}

static inline void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
{
}

static inline unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx)
{
        return 0;
}

static inline unsigned long memcg_page_state_local(struct mem_cgroup *memcg,
                                                   int idx)
{
        return 0;
}

static inline void __mod_memcg_state(struct mem_cgroup *memcg,
                                     int idx,
                                     int nr)
{
}

static inline void mod_memcg_state(struct mem_cgroup *memcg,
                                   int idx,
                                   int nr)
{
}

static inline unsigned long lruvec_page_state(struct lruvec *lruvec,
                                              enum node_stat_item idx)
{
        return node_page_state(lruvec_pgdat(lruvec), idx);
}

static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec,
                                                    enum node_stat_item idx)
{
        return node_page_state(lruvec_pgdat(lruvec), idx);
}

static inline void __mod_memcg_lruvec_state(struct lruvec *lruvec,
                                            enum node_stat_item idx, int val)
{
}

static inline void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx,
                                           int val)
{
        struct page *page = virt_to_head_page(p);

        __mod_node_page_state(page_pgdat(page), idx, val);
}

static inline void mod_lruvec_kmem_state(void *p, enum node_stat_item idx,
                                         int val)
{
        struct page *page = virt_to_head_page(p);

        mod_node_page_state(page_pgdat(page), idx, val);
}

static inline
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, 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 count_memcg_events(struct mem_cgroup *memcg,
                                      enum vm_event_item idx,
                                      unsigned long count)
{
}

static inline void __count_memcg_events(struct mem_cgroup *memcg,
                                        enum vm_event_item idx,
                                        unsigned long count)
{
}

static inline void count_memcg_page_event(struct page *page,
                                          int idx)
{
}

static inline
void count_memcg_event_mm(struct mm_struct *mm, enum vm_event_item idx)
{
}

static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
{
}
#endif /* CONFIG_MEMCG */

static inline void __inc_lruvec_kmem_state(void *p, enum node_stat_item idx)
{
        __mod_lruvec_kmem_state(p, idx, 1);
}

static inline void __dec_lruvec_kmem_state(void *p, enum node_stat_item idx)
{
        __mod_lruvec_kmem_state(p, idx, -1);
}

static inline struct lruvec *parent_lruvec(struct lruvec *lruvec)
{
        struct mem_cgroup *memcg;

        memcg = lruvec_memcg(lruvec);
        if (!memcg)
                return NULL;
        memcg = parent_mem_cgroup(memcg);
        if (!memcg)
                return NULL;
        return mem_cgroup_lruvec(memcg, lruvec_pgdat(lruvec));
}

static inline void unlock_page_lruvec(struct lruvec *lruvec)
{
        spin_unlock(&lruvec->lru_lock);
}

static inline void unlock_page_lruvec_irq(struct lruvec *lruvec)
{
        spin_unlock_irq(&lruvec->lru_lock);
}

static inline void unlock_page_lruvec_irqrestore(struct lruvec *lruvec,
                unsigned long flags)
{
        spin_unlock_irqrestore(&lruvec->lru_lock, flags);
}

/* Don't lock again iff page's lruvec locked */
static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
                struct lruvec *locked_lruvec)
{
        if (locked_lruvec) {
                if (lruvec_holds_page_lru_lock(page, locked_lruvec))
                        return locked_lruvec;

                unlock_page_lruvec_irq(locked_lruvec);
        }

        return lock_page_lruvec_irq(page);
}

/* Don't lock again iff page's lruvec locked */
static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
                struct lruvec *locked_lruvec, unsigned long *flags)
{
        if (locked_lruvec) {
                if (lruvec_holds_page_lru_lock(page, locked_lruvec))
                        return locked_lruvec;

                unlock_page_lruvec_irqrestore(locked_lruvec, *flags);
        }

        return lock_page_lruvec_irqsave(page, flags);
}

#ifdef CONFIG_CGROUP_WRITEBACK

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);

void mem_cgroup_track_foreign_dirty_slowpath(struct page *page,
                                             struct bdi_writeback *wb);

static inline void mem_cgroup_track_foreign_dirty(struct page *page,
                                                  struct bdi_writeback *wb)
{
        if (mem_cgroup_disabled())
                return;

        if (unlikely(&page_memcg(page)->css != wb->memcg_css))
                mem_cgroup_track_foreign_dirty_slowpath(page, wb);
}

void mem_cgroup_flush_foreign(struct bdi_writeback *wb);

#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)
{
}

static inline void mem_cgroup_track_foreign_dirty(struct page *page,
                                                  struct bdi_writeback *wb)
{
}

static inline void mem_cgroup_flush_foreign(struct bdi_writeback *wb)
{
}

#endif  /* CONFIG_CGROUP_WRITEBACK */

struct sock;
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)
void mem_cgroup_sk_alloc(struct sock *sk);
void mem_cgroup_sk_free(struct sock *sk);
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;
}

extern int memcg_expand_shrinker_maps(int new_id);

extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
                                   int nid, int shrinker_id);
#else
#define mem_cgroup_sockets_enabled 0
static inline void mem_cgroup_sk_alloc(struct sock *sk) { };
static inline void mem_cgroup_sk_free(struct sock *sk) { };
static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
{
        return false;
}

static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
                                          int nid, int shrinker_id)
{
}
#endif

#ifdef CONFIG_MEMCG_KMEM
int __memcg_kmem_charge(struct mem_cgroup *memcg, gfp_t gfp,
                        unsigned int nr_pages);
void __memcg_kmem_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages);
int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order);
void __memcg_kmem_uncharge_page(struct page *page, int order);

struct obj_cgroup *get_obj_cgroup_from_current(void);

int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);

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_likely(&memcg_kmem_enabled_key);
}

static inline int memcg_kmem_charge_page(struct page *page, gfp_t gfp,
                                         int order)
{
        if (memcg_kmem_enabled())
                return __memcg_kmem_charge_page(page, gfp, order);
        return 0;
}

static inline void memcg_kmem_uncharge_page(struct page *page, int order)
{
        if (memcg_kmem_enabled())
                __memcg_kmem_uncharge_page(page, order);
}

/*
 * A helper for accessing memcg's kmem_id, used for getting
 * corresponding LRU lists.
 */
static inline int memcg_cache_id(struct mem_cgroup *memcg)
{
        return memcg ? memcg->kmemcg_id : -1;
}

struct mem_cgroup *mem_cgroup_from_obj(void *p);

#else

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

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

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

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

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

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

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 mem_cgroup *mem_cgroup_from_obj(void *p)
{
       return NULL;
}

#endif /* CONFIG_MEMCG_KMEM */

#endif /* _LINUX_MEMCONTROL_H */