/* memcontrol.c - Memory Controller * * Copyright IBM Corporation, 2007 * Author Balbir Singh * * Copyright 2007 OpenVZ SWsoft Inc * Author: Pavel Emelianov * * Memory thresholds * Copyright (C) 2009 Nokia Corporation * Author: Kirill A. Shutemov * * Kernel Memory Controller * Copyright (C) 2012 Parallels Inc. and Google Inc. * Authors: Glauber Costa and Suleiman Souhlal * * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" #include #include #include #include #include struct cgroup_subsys mem_cgroup_subsys __read_mostly; EXPORT_SYMBOL(mem_cgroup_subsys); #define MEM_CGROUP_RECLAIM_RETRIES 5 static struct mem_cgroup *root_mem_cgroup __read_mostly; #ifdef CONFIG_MEMCG_SWAP /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */ int do_swap_account __read_mostly; /* for remember boot option*/ #ifdef CONFIG_MEMCG_SWAP_ENABLED static int really_do_swap_account __initdata = 1; #else static int really_do_swap_account __initdata = 0; #endif #else #define do_swap_account 0 #endif static const char * const mem_cgroup_stat_names[] = { "cache", "rss", "rss_huge", "mapped_file", "writeback", "swap", }; 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, }; static const char * const mem_cgroup_events_names[] = { "pgpgin", "pgpgout", "pgfault", "pgmajfault", }; static const char * const mem_cgroup_lru_names[] = { "inactive_anon", "active_anon", "inactive_file", "active_file", "unevictable", }; /* * 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, }; #define THRESHOLDS_EVENTS_TARGET 128 #define SOFTLIMIT_EVENTS_TARGET 1024 #define NUMAINFO_EVENTS_TARGET 1024 struct mem_cgroup_stat_cpu { long count[MEM_CGROUP_STAT_NSTATS]; unsigned long events[MEM_CGROUP_EVENTS_NSTATS]; unsigned long nr_page_events; unsigned long targets[MEM_CGROUP_NTARGETS]; }; struct mem_cgroup_reclaim_iter { /* * last scanned hierarchy member. Valid only if last_dead_count * matches memcg->dead_count of the hierarchy root group. */ struct mem_cgroup *last_visited; unsigned long last_dead_count; /* 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 reclaim_iter[DEF_PRIORITY + 1]; 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; u64 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; }; /* for OOM */ struct mem_cgroup_eventfd_list { struct list_head list; struct eventfd_ctx *eventfd; }; static void mem_cgroup_threshold(struct mem_cgroup *memcg); static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); /* * 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. * * TODO: Add a water mark for the memory controller. Reclaim will begin when * we hit the water mark. May be even add a low water mark, such that * no reclaim occurs from a cgroup at it's low water mark, this is * a feature that will be implemented much later in the future. */ struct mem_cgroup { struct cgroup_subsys_state css; /* * the counter to account for memory usage */ struct res_counter res; /* vmpressure notifications */ struct vmpressure vmpressure; /* * the counter to account for mem+swap usage. */ struct res_counter memsw; /* * the counter to account for kernel memory usage. */ struct res_counter kmem; /* * Should the accounting and control be hierarchical, per subtree? */ bool use_hierarchy; unsigned long kmem_account_flags; /* See KMEM_ACCOUNTED_*, below */ bool oom_lock; atomic_t under_oom; atomic_t oom_wakeups; int swappiness; /* OOM-Killer disable */ int oom_kill_disable; /* set when res.limit == memsw.limit */ bool memsw_is_minimum; /* 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; /* * percpu counter. */ struct mem_cgroup_stat_cpu __percpu *stat; /* * used when a cpu is offlined or other synchronizations * See mem_cgroup_read_stat(). */ struct mem_cgroup_stat_cpu nocpu_base; spinlock_t pcp_counter_lock; atomic_t dead_count; #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET) struct tcp_memcontrol tcp_mem; #endif #if defined(CONFIG_MEMCG_KMEM) /* analogous to slab_common's slab_caches list. per-memcg */ struct list_head memcg_slab_caches; /* Not a spinlock, we can take a lot of time walking the list */ struct mutex slab_caches_mutex; /* Index in the kmem_cache->memcg_params->memcg_caches array */ int kmemcg_id; #endif int last_scanned_node; #if MAX_NUMNODES > 1 nodemask_t scan_nodes; atomic_t numainfo_events; atomic_t numainfo_updating; #endif /* * Protects soft_contributed transitions. * See mem_cgroup_update_soft_limit */ spinlock_t soft_lock; /* * If true then this group has increased parents' children_in_excess * when it got over the soft limit. * When a group falls bellow the soft limit, parents' children_in_excess * is decreased and soft_contributed changed to false. */ bool soft_contributed; /* Number of children that are in soft limit excess */ atomic_t children_in_excess; struct mem_cgroup_per_node *nodeinfo[0]; /* WARNING: nodeinfo must be the last member here */ }; static size_t memcg_size(void) { return sizeof(struct mem_cgroup) + nr_node_ids * sizeof(struct mem_cgroup_per_node); } /* internal only representation about the status of kmem accounting. */ enum { KMEM_ACCOUNTED_ACTIVE = 0, /* accounted by this cgroup itself */ KMEM_ACCOUNTED_ACTIVATED, /* static key enabled. */ KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */ }; /* We account when limit is on, but only after call sites are patched */ #define KMEM_ACCOUNTED_MASK \ ((1 << KMEM_ACCOUNTED_ACTIVE) | (1 << KMEM_ACCOUNTED_ACTIVATED)) #ifdef CONFIG_MEMCG_KMEM static inline void memcg_kmem_set_active(struct mem_cgroup *memcg) { set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); } static bool memcg_kmem_is_active(struct mem_cgroup *memcg) { return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); } static void memcg_kmem_set_activated(struct mem_cgroup *memcg) { set_bit(KMEM_ACCOUNTED_ACTIVATED, &memcg->kmem_account_flags); } static void memcg_kmem_clear_activated(struct mem_cgroup *memcg) { clear_bit(KMEM_ACCOUNTED_ACTIVATED, &memcg->kmem_account_flags); } static void memcg_kmem_mark_dead(struct mem_cgroup *memcg) { /* * Our caller must use css_get() first, because memcg_uncharge_kmem() * will call css_put() if it sees the memcg is dead. */ smp_wmb(); if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags)) set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags); } static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg) { return test_and_clear_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags); } #endif /* Stuffs for move charges at task migration. */ /* * Types of charges to be moved. "move_charge_at_immitgrate" and * "immigrate_flags" are treated as a left-shifted bitmap of these types. */ enum move_type { MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */ MOVE_CHARGE_TYPE_FILE, /* file page(including tmpfs) and swap of it */ NR_MOVE_TYPE, }; /* "mc" and its members are protected by cgroup_mutex */ static struct move_charge_struct { spinlock_t lock; /* for from, to */ struct mem_cgroup *from; struct mem_cgroup *to; unsigned long immigrate_flags; unsigned long precharge; unsigned long moved_charge; unsigned long moved_swap; struct task_struct *moving_task; /* a task moving charges */ wait_queue_head_t waitq; /* a waitq for other context */ } mc = { .lock = __SPIN_LOCK_UNLOCKED(mc.lock), .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), }; static bool move_anon(void) { return test_bit(MOVE_CHARGE_TYPE_ANON, &mc.immigrate_flags); } static bool move_file(void) { return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.immigrate_flags); } /* * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft * limit reclaim to prevent infinite loops, if they ever occur. */ #define MEM_CGROUP_MAX_RECLAIM_LOOPS 100 enum charge_type { MEM_CGROUP_CHARGE_TYPE_CACHE = 0, MEM_CGROUP_CHARGE_TYPE_ANON, MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */ MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */ NR_CHARGE_TYPE, }; /* for encoding cft->private value on file */ enum res_type { _MEM, _MEMSWAP, _OOM_TYPE, _KMEM, }; #define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val)) #define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff) #define MEMFILE_ATTR(val) ((val) & 0xffff) /* Used for OOM nofiier */ #define OOM_CONTROL (0) /* * Reclaim flags for mem_cgroup_hierarchical_reclaim */ #define MEM_CGROUP_RECLAIM_NOSWAP_BIT 0x0 #define MEM_CGROUP_RECLAIM_NOSWAP (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT) #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) /* * The memcg_create_mutex will be held whenever a new cgroup is created. * As a consequence, any change that needs to protect against new child cgroups * appearing has to hold it as well. */ static DEFINE_MUTEX(memcg_create_mutex); struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s) { return s ? container_of(s, struct mem_cgroup, css) : NULL; } /* Some nice accessors for the vmpressure. */ struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg) { if (!memcg) memcg = root_mem_cgroup; return &memcg->vmpressure; } struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr) { return &container_of(vmpr, struct mem_cgroup, vmpressure)->css; } struct vmpressure *css_to_vmpressure(struct cgroup_subsys_state *css) { return &mem_cgroup_from_css(css)->vmpressure; } static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) { return (memcg == root_mem_cgroup); } static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) { /* * The ID of the root cgroup is 0, but memcg treat 0 as an * invalid ID, so we return (cgroup_id + 1). */ return memcg->css.cgroup->id + 1; } static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) { struct cgroup_subsys_state *css; css = css_from_id(id - 1, &mem_cgroup_subsys); return mem_cgroup_from_css(css); } /* Writing them here to avoid exposing memcg's inner layout */ #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM) void sock_update_memcg(struct sock *sk) { if (mem_cgroup_sockets_enabled) { struct mem_cgroup *memcg; struct cg_proto *cg_proto; BUG_ON(!sk->sk_prot->proto_cgroup); /* Socket cloning can throw us here with sk_cgrp already * filled. It won't however, necessarily happen from * process context. So the test for root memcg given * the current task's memcg won't help us in this case. * * Respecting the original socket's memcg is a better * decision in this case. */ if (sk->sk_cgrp) { BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg)); css_get(&sk->sk_cgrp->memcg->css); return; } rcu_read_lock(); memcg = mem_cgroup_from_task(current); cg_proto = sk->sk_prot->proto_cgroup(memcg); if (!mem_cgroup_is_root(memcg) && memcg_proto_active(cg_proto) && css_tryget(&memcg->css)) { sk->sk_cgrp = cg_proto; } rcu_read_unlock(); } } EXPORT_SYMBOL(sock_update_memcg); void sock_release_memcg(struct sock *sk) { if (mem_cgroup_sockets_enabled && sk->sk_cgrp) { struct mem_cgroup *memcg; WARN_ON(!sk->sk_cgrp->memcg); memcg = sk->sk_cgrp->memcg; css_put(&sk->sk_cgrp->memcg->css); } } struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg) { if (!memcg || mem_cgroup_is_root(memcg)) return NULL; return &memcg->tcp_mem.cg_proto; } EXPORT_SYMBOL(tcp_proto_cgroup); static void disarm_sock_keys(struct mem_cgroup *memcg) { if (!memcg_proto_activated(&memcg->tcp_mem.cg_proto)) return; static_key_slow_dec(&memcg_socket_limit_enabled); } #else static void disarm_sock_keys(struct mem_cgroup *memcg) { } #endif #ifdef CONFIG_MEMCG_KMEM /* * This will be the memcg's index in each cache's ->memcg_params->memcg_caches. * There are two main reasons for not using the css_id for this: * 1) this works better in sparse environments, where we have a lot of memcgs, * but only a few kmem-limited. Or also, if we have, for instance, 200 * memcgs, and none but the 200th is kmem-limited, we'd have to have a * 200 entry array for that. * * 2) In order not to violate the cgroup API, we would like to do all memory * allocation in ->create(). At that point, we haven't yet allocated the * css_id. Having a separate index prevents us from messing with the cgroup * core for this * * The current size of the caches array is stored in * memcg_limited_groups_array_size. It will double each time we have to * increase it. */ static DEFINE_IDA(kmem_limited_groups); int memcg_limited_groups_array_size; /* * MIN_SIZE is different than 1, because we would like to avoid going through * the alloc/free process all the time. In a small machine, 4 kmem-limited * cgroups is a reasonable guess. In the future, it could be a parameter or * tunable, but that is strictly not necessary. * * MAX_SIZE should be as large as the number of css_ids. Ideally, we could get * this constant directly from cgroup, but it is understandable that this is * better kept as an internal representation in cgroup.c. In any case, the * css_id space is not getting any smaller, and we don't have to necessarily * increase ours as well if it increases. */ #define MEMCG_CACHES_MIN_SIZE 4 #define MEMCG_CACHES_MAX_SIZE 65535 /* * A lot of the calls to the cache allocation functions are expected to be * inlined by the compiler. Since the calls to memcg_kmem_get_cache are * conditional to this static branch, we'll have to allow modules that does * kmem_cache_alloc and the such to see this symbol as well */ struct static_key memcg_kmem_enabled_key; EXPORT_SYMBOL(memcg_kmem_enabled_key); static void disarm_kmem_keys(struct mem_cgroup *memcg) { if (memcg_kmem_is_active(memcg)) { static_key_slow_dec(&memcg_kmem_enabled_key); ida_simple_remove(&kmem_limited_groups, memcg->kmemcg_id); } /* * This check can't live in kmem destruction function, * since the charges will outlive the cgroup */ WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0); } #else static void disarm_kmem_keys(struct mem_cgroup *memcg) { } #endif /* CONFIG_MEMCG_KMEM */ static void disarm_static_keys(struct mem_cgroup *memcg) { disarm_sock_keys(memcg); disarm_kmem_keys(memcg); } static void drain_all_stock_async(struct mem_cgroup *memcg); static struct mem_cgroup_per_zone * mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid) { VM_BUG_ON((unsigned)nid >= nr_node_ids); return &memcg->nodeinfo[nid]->zoneinfo[zid]; } struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg) { return &memcg->css; } static struct mem_cgroup_per_zone * page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page) { int nid = page_to_nid(page); int zid = page_zonenum(page); return mem_cgroup_zoneinfo(memcg, nid, zid); } /* * Implementation Note: reading percpu statistics for memcg. * * Both of vmstat[] and percpu_counter has threshold and do periodic * synchronization to implement "quick" read. There are trade-off between * reading cost and precision of value. Then, we may have a chance to implement * a periodic synchronizion of counter in memcg's counter. * * But this _read() function is used for user interface now. The user accounts * memory usage by memory cgroup and he _always_ requires exact value because * he accounts memory. Even if we provide quick-and-fuzzy read, we always * have to visit all online cpus and make sum. So, for now, unnecessary * synchronization is not implemented. (just implemented for cpu hotplug) * * If there are kernel internal actions which can make use of some not-exact * value, and reading all cpu value can be performance bottleneck in some * common workload, threashold and synchonization as vmstat[] should be * implemented. */ static long mem_cgroup_read_stat(struct mem_cgroup *memcg, enum mem_cgroup_stat_index idx) { long val = 0; int cpu; get_online_cpus(); for_each_online_cpu(cpu) val += per_cpu(memcg->stat->count[idx], cpu); #ifdef CONFIG_HOTPLUG_CPU spin_lock(&memcg->pcp_counter_lock); val += memcg->nocpu_base.count[idx]; spin_unlock(&memcg->pcp_counter_lock); #endif put_online_cpus(); return val; } static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg, bool charge) { int val = (charge) ? 1 : -1; this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val); } static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg, enum mem_cgroup_events_index idx) { unsigned long val = 0; int cpu; for_each_online_cpu(cpu) val += per_cpu(memcg->stat->events[idx], cpu); #ifdef CONFIG_HOTPLUG_CPU spin_lock(&memcg->pcp_counter_lock); val += memcg->nocpu_base.events[idx]; spin_unlock(&memcg->pcp_counter_lock); #endif return val; } static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, struct page *page, bool anon, int nr_pages) { preempt_disable(); /* * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is * counted as CACHE even if it's on ANON LRU. */ if (anon) __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS], nr_pages); else __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE], nr_pages); if (PageTransHuge(page)) __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], nr_pages); /* pagein of a big page is an event. So, ignore page size */ if (nr_pages > 0) __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]); else { __this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]); nr_pages = -nr_pages; /* for event */ } __this_cpu_add(memcg->stat->nr_page_events, nr_pages); preempt_enable(); } 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 unsigned long mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid, unsigned int lru_mask) { struct mem_cgroup_per_zone *mz; enum lru_list lru; unsigned long ret = 0; mz = mem_cgroup_zoneinfo(memcg, nid, zid); for_each_lru(lru) { if (BIT(lru) & lru_mask) ret += mz->lru_size[lru]; } return ret; } static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, int nid, unsigned int lru_mask) { u64 total = 0; int zid; for (zid = 0; zid < MAX_NR_ZONES; zid++) total += mem_cgroup_zone_nr_lru_pages(memcg, nid, zid, lru_mask); return total; } static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, unsigned int lru_mask) { int nid; u64 total = 0; for_each_node_state(nid, N_MEMORY) total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask); return total; } static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, enum mem_cgroup_events_target target) { unsigned long val, next; val = __this_cpu_read(memcg->stat->nr_page_events); next = __this_cpu_read(memcg->stat->targets[target]); /* from time_after() in jiffies.h */ if ((long)next - (long)val < 0) { switch (target) { case MEM_CGROUP_TARGET_THRESH: next = val + THRESHOLDS_EVENTS_TARGET; break; case MEM_CGROUP_TARGET_SOFTLIMIT: next = val + SOFTLIMIT_EVENTS_TARGET; break; case MEM_CGROUP_TARGET_NUMAINFO: next = val + NUMAINFO_EVENTS_TARGET; break; default: break; } __this_cpu_write(memcg->stat->targets[target], next); return true; } return false; } /* * Called from rate-limited memcg_check_events when enough * MEM_CGROUP_TARGET_SOFTLIMIT events are accumulated and it makes sure * that all the parents up the hierarchy will be notified that this group * is in excess or that it is not in excess anymore. mmecg->soft_contributed * makes the transition a single action whenever the state flips from one to * the other. */ static void mem_cgroup_update_soft_limit(struct mem_cgroup *memcg) { unsigned long long excess = res_counter_soft_limit_excess(&memcg->res); struct mem_cgroup *parent = memcg; int delta = 0; spin_lock(&memcg->soft_lock); if (excess) { if (!memcg->soft_contributed) { delta = 1; memcg->soft_contributed = true; } } else { if (memcg->soft_contributed) { delta = -1; memcg->soft_contributed = false; } } /* * Necessary to update all ancestors when hierarchy is used * because their event counter is not touched. * We track children even outside the hierarchy for the root * cgroup because tree walk starting at root should visit * all cgroups and we want to prevent from pointless tree * walk if no children is below the limit. */ while (delta && (parent = parent_mem_cgroup(parent))) atomic_add(delta, &parent->children_in_excess); if (memcg != root_mem_cgroup && !root_mem_cgroup->use_hierarchy) atomic_add(delta, &root_mem_cgroup->children_in_excess); spin_unlock(&memcg->soft_lock); } /* * Check events in order. * */ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) { preempt_disable(); /* threshold event is triggered in finer grain than soft limit */ if (unlikely(mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_THRESH))) { bool do_softlimit; bool do_numainfo __maybe_unused; do_softlimit = mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_SOFTLIMIT); #if MAX_NUMNODES > 1 do_numainfo = mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_NUMAINFO); #endif preempt_enable(); mem_cgroup_threshold(memcg); if (unlikely(do_softlimit)) mem_cgroup_update_soft_limit(memcg); #if MAX_NUMNODES > 1 if (unlikely(do_numainfo)) atomic_inc(&memcg->numainfo_events); #endif } else preempt_enable(); } struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) { /* * mm_update_next_owner() may clear mm->owner to NULL * if it races with swapoff, page migration, etc. * So this can be called with p == NULL. */ if (unlikely(!p)) return NULL; return mem_cgroup_from_css(task_css(p, mem_cgroup_subsys_id)); } struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) { struct mem_cgroup *memcg = NULL; if (!mm) return NULL; /* * Because we have no locks, mm->owner's may be being moved to other * cgroup. We use css_tryget() here even if this looks * pessimistic (rather than adding locks here). */ rcu_read_lock(); do { memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); if (unlikely(!memcg)) break; } while (!css_tryget(&memcg->css)); rcu_read_unlock(); return memcg; } static enum mem_cgroup_filter_t mem_cgroup_filter(struct mem_cgroup *memcg, struct mem_cgroup *root, mem_cgroup_iter_filter cond) { if (!cond) return VISIT; return cond(memcg, root); } /* * Returns a next (in a pre-order walk) alive memcg (with elevated css * ref. count) or NULL if the whole root's subtree has been visited. * * helper function to be used by mem_cgroup_iter */ static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root, struct mem_cgroup *last_visited, mem_cgroup_iter_filter cond) { struct cgroup_subsys_state *prev_css, *next_css; prev_css = last_visited ? &last_visited->css : NULL; skip_node: next_css = css_next_descendant_pre(prev_css, &root->css); /* * Even if we found a group we have to make sure it is * alive. css && !memcg means that the groups should be * skipped and we should continue the tree walk. * last_visited css is safe to use because it is * protected by css_get and the tree walk is rcu safe. */ if (next_css) { struct mem_cgroup *mem = mem_cgroup_from_css(next_css); switch (mem_cgroup_filter(mem, root, cond)) { case SKIP: prev_css = next_css; goto skip_node; case SKIP_TREE: if (mem == root) return NULL; /* * css_rightmost_descendant is not an optimal way to * skip through a subtree (especially for imbalanced * trees leaning to right) but that's what we have right * now. More effective solution would be traversing * right-up for first non-NULL without calling * css_next_descendant_pre afterwards. */ prev_css = css_rightmost_descendant(next_css); goto skip_node; case VISIT: if (css_tryget(&mem->css)) return mem; else { prev_css = next_css; goto skip_node; } break; } } return NULL; } static void mem_cgroup_iter_invalidate(struct mem_cgroup *root) { /* * When a group in the hierarchy below root is destroyed, the * hierarchy iterator can no longer be trusted since it might * have pointed to the destroyed group. Invalidate it. */ atomic_inc(&root->dead_count); } static struct mem_cgroup * mem_cgroup_iter_load(struct mem_cgroup_reclaim_iter *iter, struct mem_cgroup *root, int *sequence) { struct mem_cgroup *position = NULL; /* * A cgroup destruction happens in two stages: offlining and * release. They are separated by a RCU grace period. * * If the iterator is valid, we may still race with an * offlining. The RCU lock ensures the object won't be * released, tryget will fail if we lost the race. */ *sequence = atomic_read(&root->dead_count); if (iter->last_dead_count == *sequence) { smp_rmb(); position = iter->last_visited; if (position && !css_tryget(&position->css)) position = NULL; } return position; } static void mem_cgroup_iter_update(struct mem_cgroup_reclaim_iter *iter, struct mem_cgroup *last_visited, struct mem_cgroup *new_position, int sequence) { if (last_visited) css_put(&last_visited->css); /* * We store the sequence count from the time @last_visited was * loaded successfully instead of rereading it here so that we * don't lose destruction events in between. We could have * raced with the destruction of @new_position after all. */ iter->last_visited = new_position; smp_wmb(); iter->last_dead_count = sequence; } /** * mem_cgroup_iter - iterate over memory cgroup hierarchy * @root: hierarchy root * @prev: previously returned memcg, NULL on first invocation * @reclaim: cookie for shared reclaim walks, NULL for full walks * @cond: filter for visited nodes, NULL for no filter * * Returns references to children of the hierarchy below @root, or * @root itself, or %NULL after a full round-trip. * * Caller must pass the return value in @prev on subsequent * invocations for reference counting, or use mem_cgroup_iter_break() * to cancel a hierarchy walk before the round-trip is complete. * * Reclaimers can specify a zone and a priority level in @reclaim to * divide up the memcgs in the hierarchy among all concurrent * reclaimers operating on the same zone and priority. */ struct mem_cgroup *mem_cgroup_iter_cond(struct mem_cgroup *root, struct mem_cgroup *prev, struct mem_cgroup_reclaim_cookie *reclaim, mem_cgroup_iter_filter cond) { struct mem_cgroup *memcg = NULL; struct mem_cgroup *last_visited = NULL; if (mem_cgroup_disabled()) { /* first call must return non-NULL, second return NULL */ return (struct mem_cgroup *)(unsigned long)!prev; } if (!root) root = root_mem_cgroup; if (prev && !reclaim) last_visited = prev; if (!root->use_hierarchy && root != root_mem_cgroup) { if (prev) goto out_css_put; if (mem_cgroup_filter(root, root, cond) == VISIT) return root; return NULL; } rcu_read_lock(); while (!memcg) { struct mem_cgroup_reclaim_iter *uninitialized_var(iter); int uninitialized_var(seq); if (reclaim) { int nid = zone_to_nid(reclaim->zone); int zid = zone_idx(reclaim->zone); struct mem_cgroup_per_zone *mz; mz = mem_cgroup_zoneinfo(root, nid, zid); iter = &mz->reclaim_iter[reclaim->priority]; if (prev && reclaim->generation != iter->generation) { iter->last_visited = NULL; goto out_unlock; } last_visited = mem_cgroup_iter_load(iter, root, &seq); } memcg = __mem_cgroup_iter_next(root, last_visited, cond); if (reclaim) { mem_cgroup_iter_update(iter, last_visited, memcg, seq); if (!memcg) iter->generation++; else if (!prev && memcg) reclaim->generation = iter->generation; } /* * We have finished the whole tree walk or no group has been * visited because filter told us to skip the root node. */ if (!memcg && (prev || (cond && !last_visited))) goto out_unlock; } out_unlock: rcu_read_unlock(); out_css_put: if (prev && prev != root) css_put(&prev->css); return memcg; } /** * mem_cgroup_iter_break - abort a hierarchy walk prematurely * @root: hierarchy root * @prev: last visited hierarchy member as returned by mem_cgroup_iter() */ void mem_cgroup_iter_break(struct mem_cgroup *root, struct mem_cgroup *prev) { if (!root) root = root_mem_cgroup; if (prev && prev != root) css_put(&prev->css); } /* * Iteration constructs for visiting all cgroups (under a tree). If * loops are exited prematurely (break), mem_cgroup_iter_break() must * be used for reference counting. */ #define for_each_mem_cgroup_tree(iter, root) \ for (iter = mem_cgroup_iter(root, NULL, NULL); \ iter != NULL; \ iter = mem_cgroup_iter(root, iter, NULL)) #define for_each_mem_cgroup(iter) \ for (iter = mem_cgroup_iter(NULL, NULL, NULL); \ iter != NULL; \ iter = mem_cgroup_iter(NULL, iter, NULL)) void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx) { struct mem_cgroup *memcg; 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(); } EXPORT_SYMBOL(__mem_cgroup_count_vm_event); /** * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg * @zone: zone of the wanted lruvec * @memcg: memcg of the wanted lruvec * * Returns the lru list vector holding pages for the given @zone and * @mem. This can be the global zone lruvec, if the memory controller * is disabled. */ struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone, struct mem_cgroup *memcg) { struct mem_cgroup_per_zone *mz; struct lruvec *lruvec; if (mem_cgroup_disabled()) { lruvec = &zone->lruvec; goto out; } mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone)); lruvec = &mz->lruvec; out: /* * Since a node can be onlined after the mem_cgroup was created, * we have to be prepared to initialize lruvec->zone here; * and if offlined then reonlined, we need to reinitialize it. */ if (unlikely(lruvec->zone != zone)) lruvec->zone = zone; return lruvec; } /* * Following LRU functions are allowed to be used without PCG_LOCK. * Operations are called by routine of global LRU independently from memcg. * What we have to take care of here is validness of pc->mem_cgroup. * * Changes to pc->mem_cgroup happens when * 1. charge * 2. moving account * In typical case, "charge" is done before add-to-lru. Exception is SwapCache. * It is added to LRU before charge. * If PCG_USED bit is not set, page_cgroup is not added to this private LRU. * When moving account, the page is not on LRU. It's isolated. */ /** * mem_cgroup_page_lruvec - return lruvec for adding an lru page * @page: the page * @zone: zone of the page */ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct zone *zone) { struct mem_cgroup_per_zone *mz; struct mem_cgroup *memcg; struct page_cgroup *pc; struct lruvec *lruvec; if (mem_cgroup_disabled()) { lruvec = &zone->lruvec; goto out; } pc = lookup_page_cgroup(page); memcg = pc->mem_cgroup; /* * Surreptitiously switch any uncharged offlist page to root: * an uncharged page off lru does nothing to secure * its former mem_cgroup from sudden removal. * * Our caller holds lru_lock, and PageCgroupUsed is updated * under page_cgroup lock: between them, they make all uses * of pc->mem_cgroup safe. */ if (!PageLRU(page) && !PageCgroupUsed(pc) && memcg != root_mem_cgroup) pc->mem_cgroup = memcg = root_mem_cgroup; mz = page_cgroup_zoneinfo(memcg, page); lruvec = &mz->lruvec; out: /* * Since a node can be onlined after the mem_cgroup was created, * we have to be prepared to initialize lruvec->zone here; * and if offlined then reonlined, we need to reinitialize it. */ if (unlikely(lruvec->zone != zone)) lruvec->zone = zone; return lruvec; } /** * mem_cgroup_update_lru_size - account for adding or removing an lru page * @lruvec: mem_cgroup per zone lru vector * @lru: index of lru list the page is sitting on * @nr_pages: positive when adding or negative when removing * * This function must be called when a page is added to or removed from an * lru list. */ void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, int nr_pages) { struct mem_cgroup_per_zone *mz; unsigned long *lru_size; if (mem_cgroup_disabled()) return; mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec); lru_size = mz->lru_size + lru; *lru_size += nr_pages; VM_BUG_ON((long)(*lru_size) < 0); } /* * Checks whether given mem is same or in the root_mem_cgroup's * hierarchy subtree */ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg, struct mem_cgroup *memcg) { if (root_memcg == memcg) return true; if (!root_memcg->use_hierarchy || !memcg) return false; return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup); } static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg, struct mem_cgroup *memcg) { bool ret; rcu_read_lock(); ret = __mem_cgroup_same_or_subtree(root_memcg, memcg); rcu_read_unlock(); return ret; } bool task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg) { struct mem_cgroup *curr = NULL; struct task_struct *p; bool ret; p = find_lock_task_mm(task); if (p) { curr = try_get_mem_cgroup_from_mm(p->mm); task_unlock(p); } else { /* * All threads may have already detached their mm's, but the oom * killer still needs to detect if they have already been oom * killed to prevent needlessly killing additional tasks. */ rcu_read_lock(); curr = mem_cgroup_from_task(task); if (curr) css_get(&curr->css); rcu_read_unlock(); } if (!curr) return false; /* * We should check use_hierarchy of "memcg" not "curr". Because checking * use_hierarchy of "curr" here make this function true if hierarchy is * enabled in "curr" and "curr" is a child of "memcg" in *cgroup* * hierarchy(even if use_hierarchy is disabled in "memcg"). */ ret = mem_cgroup_same_or_subtree(memcg, curr); css_put(&curr->css); return ret; } int 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; } #define mem_cgroup_from_res_counter(counter, member) \ container_of(counter, struct mem_cgroup, member) /** * mem_cgroup_margin - calculate chargeable space of a memory cgroup * @memcg: the memory cgroup * * Returns the maximum amount of memory @mem can be charged with, in * pages. */ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg) { unsigned long long margin; margin = res_counter_margin(&memcg->res); if (do_swap_account) margin = min(margin, res_counter_margin(&memcg->memsw)); return margin >> PAGE_SHIFT; } int mem_cgroup_swappiness(struct mem_cgroup *memcg) { /* root ? */ if (!css_parent(&memcg->css)) return vm_swappiness; return memcg->swappiness; } /* * memcg->moving_account is used for checking possibility that some thread is * calling move_account(). When a thread on CPU-A starts moving pages under * a memcg, other threads should check memcg->moving_account under * rcu_read_lock(), like this: * * CPU-A CPU-B * rcu_read_lock() * memcg->moving_account+1 if (memcg->mocing_account) * take heavy locks. * synchronize_rcu() update something. * rcu_read_unlock() * start move here. */ /* for quick checking without looking up memcg */ atomic_t memcg_moving __read_mostly; static void mem_cgroup_start_move(struct mem_cgroup *memcg) { atomic_inc(&memcg_moving); atomic_inc(&memcg->moving_account); synchronize_rcu(); } static void mem_cgroup_end_move(struct mem_cgroup *memcg) { /* * Now, mem_cgroup_clear_mc() may call this function with NULL. * We check NULL in callee rather than caller. */ if (memcg) { atomic_dec(&memcg_moving); atomic_dec(&memcg->moving_account); } } /* * 2 routines for checking "mem" is under move_account() or not. * * mem_cgroup_stolen() - checking whether a cgroup is mc.from or not. This * is used for avoiding races in accounting. If true, * pc->mem_cgroup may be overwritten. * * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or * under hierarchy of moving cgroups. This is for * waiting at hith-memory prressure caused by "move". */ static bool mem_cgroup_stolen(struct mem_cgroup *memcg) { VM_BUG_ON(!rcu_read_lock_held()); return atomic_read(&memcg->moving_account) > 0; } static bool mem_cgroup_under_move(struct mem_cgroup *memcg) { struct mem_cgroup *from; struct mem_cgroup *to; bool ret = false; /* * Unlike task_move routines, we access mc.to, mc.from not under * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. */ spin_lock(&mc.lock); from = mc.from; to = mc.to; if (!from) goto unlock; ret = mem_cgroup_same_or_subtree(memcg, from) || mem_cgroup_same_or_subtree(memcg, to); unlock: spin_unlock(&mc.lock); return ret; } static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) { if (mc.moving_task && current != mc.moving_task) { if (mem_cgroup_under_move(memcg)) { DEFINE_WAIT(wait); prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); /* moving charge context might have finished. */ if (mc.moving_task) schedule(); finish_wait(&mc.waitq, &wait); return true; } } return false; } /* * Take this lock when * - a code tries to modify page's memcg while it's USED. * - a code tries to modify page state accounting in a memcg. * see mem_cgroup_stolen(), too. */ static void move_lock_mem_cgroup(struct mem_cgroup *memcg, unsigned long *flags) { spin_lock_irqsave(&memcg->move_lock, *flags); } static void move_unlock_mem_cgroup(struct mem_cgroup *memcg, unsigned long *flags) { spin_unlock_irqrestore(&memcg->move_lock, *flags); } #define K(x) ((x) << (PAGE_SHIFT-10)) /** * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller. * @memcg: The memory cgroup that went over limit * @p: Task that is going to be killed * * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is * enabled */ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) { struct cgroup *task_cgrp; struct cgroup *mem_cgrp; /* * Need a buffer in BSS, can't rely on allocations. The code relies * on the assumption that OOM is serialized for memory controller. * If this assumption is broken, revisit this code. */ static char memcg_name[PATH_MAX]; int ret; struct mem_cgroup *iter; unsigned int i; if (!p) return; rcu_read_lock(); mem_cgrp = memcg->css.cgroup; task_cgrp = task_cgroup(p, mem_cgroup_subsys_id); ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX); if (ret < 0) { /* * Unfortunately, we are unable to convert to a useful name * But we'll still print out the usage information */ rcu_read_unlock(); goto done; } rcu_read_unlock(); pr_info("Task in %s killed", memcg_name); rcu_read_lock(); ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX); if (ret < 0) { rcu_read_unlock(); goto done; } rcu_read_unlock(); /* * Continues from above, so we don't need an KERN_ level */ pr_cont(" as a result of limit of %s\n", memcg_name); done: pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE) >> 10, res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10, res_counter_read_u64(&memcg->res, RES_FAILCNT)); pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n", res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10, res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10, res_counter_read_u64(&memcg->memsw, RES_FAILCNT)); pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n", res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10, res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10, res_counter_read_u64(&memcg->kmem, RES_FAILCNT)); for_each_mem_cgroup_tree(iter, memcg) { pr_info("Memory cgroup stats"); rcu_read_lock(); ret = cgroup_path(iter->css.cgroup, memcg_name, PATH_MAX); if (!ret) pr_cont(" for %s", memcg_name); rcu_read_unlock(); pr_cont(":"); for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) continue; pr_cont(" %s:%ldKB", mem_cgroup_stat_names[i], K(mem_cgroup_read_stat(iter, i))); } for (i = 0; i < NR_LRU_LISTS; i++) pr_cont(" %s:%luKB", mem_cgroup_lru_names[i], K(mem_cgroup_nr_lru_pages(iter, BIT(i)))); pr_cont("\n"); } } /* * This function returns the number of memcg under hierarchy tree. Returns * 1(self count) if no children. */ static int mem_cgroup_count_children(struct mem_cgroup *memcg) { int num = 0; struct mem_cgroup *iter; for_each_mem_cgroup_tree(iter, memcg) num++; return num; } /* * Return the memory (and swap, if configured) limit for a memcg. */ static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg) { u64 limit; limit = res_counter_read_u64(&memcg->res, RES_LIMIT); /* * Do not consider swap space if we cannot swap due to swappiness */ if (mem_cgroup_swappiness(memcg)) { u64 memsw; limit += total_swap_pages << PAGE_SHIFT; memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT); /* * If memsw is finite and limits the amount of swap space * available to this memcg, return that limit. */ limit = min(limit, memsw); } return limit; } static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, int order) { struct mem_cgroup *iter; unsigned long chosen_points = 0; unsigned long totalpages; unsigned int points = 0; struct task_struct *chosen = NULL; /* * If current has a pending SIGKILL or is exiting, then automatically * select it. The goal is to allow it to allocate so that it may * quickly exit and free its memory. */ if (fatal_signal_pending(current) || current->flags & PF_EXITING) { set_thread_flag(TIF_MEMDIE); return; } check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL); totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1; for_each_mem_cgroup_tree(iter, memcg) { struct css_task_iter it; struct task_struct *task; css_task_iter_start(&iter->css, &it); while ((task = css_task_iter_next(&it))) { switch (oom_scan_process_thread(task, totalpages, NULL, false)) { case OOM_SCAN_SELECT: if (chosen) put_task_struct(chosen); chosen = task; chosen_points = ULONG_MAX; get_task_struct(chosen); /* fall through */ case OOM_SCAN_CONTINUE: continue; case OOM_SCAN_ABORT: css_task_iter_end(&it); mem_cgroup_iter_break(memcg, iter); if (chosen) put_task_struct(chosen); return; case OOM_SCAN_OK: break; }; points = oom_badness(task, memcg, NULL, totalpages); if (points > chosen_points) { if (chosen) put_task_struct(chosen); chosen = task; chosen_points = points; get_task_struct(chosen); } } css_task_iter_end(&it); } if (!chosen) return; points = chosen_points * 1000 / totalpages; oom_kill_process(chosen, gfp_mask, order, points, totalpages, memcg, NULL, "Memory cgroup out of memory"); } static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned long flags) { unsigned long total = 0; bool noswap = false; int loop; if (flags & MEM_CGROUP_RECLAIM_NOSWAP) noswap = true; if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum) noswap = true; for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) { if (loop) drain_all_stock_async(memcg); total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap); /* * Allow limit shrinkers, which are triggered directly * by userspace, to catch signals and stop reclaim * after minimal progress, regardless of the margin. */ if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK)) break; if (mem_cgroup_margin(memcg)) break; /* * If nothing was reclaimed after two attempts, there * may be no reclaimable pages in this hierarchy. */ if (loop && !total) break; } return total; } #if MAX_NUMNODES > 1 /** * test_mem_cgroup_node_reclaimable * @memcg: the target memcg * @nid: the node ID to be checked. * @noswap : specify true here if the user wants flle only information. * * This function returns whether the specified memcg contains any * reclaimable pages on a node. Returns true if there are any reclaimable * pages in the node. */ static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg, int nid, bool noswap) { if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE)) return true; if (noswap || !total_swap_pages) return false; if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON)) return true; return false; } /* * Always updating the nodemask is not very good - even if we have an empty * list or the wrong list here, we can start from some node and traverse all * nodes based on the zonelist. So update the list loosely once per 10 secs. * */ static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg) { int nid; /* * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET * pagein/pageout changes since the last update. */ if (!atomic_read(&memcg->numainfo_events)) return; if (atomic_inc_return(&memcg->numainfo_updating) > 1) return; /* make a nodemask where this memcg uses memory from */ memcg->scan_nodes = node_states[N_MEMORY]; for_each_node_mask(nid, node_states[N_MEMORY]) { if (!test_mem_cgroup_node_reclaimable(memcg, nid, false)) node_clear(nid, memcg->scan_nodes); } atomic_set(&memcg->numainfo_events, 0); atomic_set(&memcg->numainfo_updating, 0); } /* * Selecting a node where we start reclaim from. Because what we need is just * reducing usage counter, start from anywhere is O,K. Considering * memory reclaim from current node, there are pros. and cons. * * Freeing memory from current node means freeing memory from a node which * we'll use or we've used. So, it may make LRU bad. And if several threads * hit limits, it will see a contention on a node. But freeing from remote * node means more costs for memory reclaim because of memory latency. * * Now, we use round-robin. Better algorithm is welcomed. */ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) { int node; mem_cgroup_may_update_nodemask(memcg); node = memcg->last_scanned_node; node = next_node(node, memcg->scan_nodes); if (node == MAX_NUMNODES) node = first_node(memcg->scan_nodes); /* * We call this when we hit limit, not when pages are added to LRU. * No LRU may hold pages because all pages are UNEVICTABLE or * memcg is too small and all pages are not on LRU. In that case, * we use curret node. */ if (unlikely(node == MAX_NUMNODES)) node = numa_node_id(); memcg->last_scanned_node = node; return node; } #else int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) { return 0; } #endif /* * A group is eligible for the soft limit reclaim under the given root * hierarchy if * a) it is over its soft limit * b) any parent up the hierarchy is over its soft limit * * If the given group doesn't have any children over the limit then it * doesn't make any sense to iterate its subtree. */ enum mem_cgroup_filter_t mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg, struct mem_cgroup *root) { struct mem_cgroup *parent; if (!memcg) memcg = root_mem_cgroup; parent = memcg; if (res_counter_soft_limit_excess(&memcg->res)) return VISIT; /* * If any parent up to the root in the hierarchy is over its soft limit * then we have to obey and reclaim from this group as well. */ while ((parent = parent_mem_cgroup(parent))) { if (res_counter_soft_limit_excess(&parent->res)) return VISIT; if (parent == root) break; } if (!atomic_read(&memcg->children_in_excess)) return SKIP_TREE; return SKIP; } static DEFINE_SPINLOCK(memcg_oom_lock); /* * Check OOM-Killer is already running under our hierarchy. * If someone is running, return false. */ static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg) { struct mem_cgroup *iter, *failed = NULL; spin_lock(&memcg_oom_lock); for_each_mem_cgroup_tree(iter, memcg) { if (iter->oom_lock) { /* * this subtree of our hierarchy is already locked * so we cannot give a lock. */ failed = iter; mem_cgroup_iter_break(memcg, iter); break; } else iter->oom_lock = true; } if (failed) { /* * OK, we failed to lock the whole subtree so we have * to clean up what we set up to the failing subtree */ for_each_mem_cgroup_tree(iter, memcg) { if (iter == failed) { mem_cgroup_iter_break(memcg, iter); break; } iter->oom_lock = false; } } spin_unlock(&memcg_oom_lock); return !failed; } static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg) { struct mem_cgroup *iter; spin_lock(&memcg_oom_lock); for_each_mem_cgroup_tree(iter, memcg) iter->oom_lock = false; spin_unlock(&memcg_oom_lock); } static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg) { struct mem_cgroup *iter; for_each_mem_cgroup_tree(iter, memcg) atomic_inc(&iter->under_oom); } static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg) { struct mem_cgroup *iter; /* * When a new child is created while the hierarchy is under oom, * mem_cgroup_oom_lock() may not be called. We have to use * atomic_add_unless() here. */ for_each_mem_cgroup_tree(iter, memcg) atomic_add_unless(&iter->under_oom, -1, 0); } static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); struct oom_wait_info { struct mem_cgroup *memcg; wait_queue_t wait; }; static int memcg_oom_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *arg) { struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg; struct mem_cgroup *oom_wait_memcg; struct oom_wait_info *oom_wait_info; oom_wait_info = container_of(wait, struct oom_wait_info, wait); oom_wait_memcg = oom_wait_info->memcg; /* * Both of oom_wait_info->memcg and wake_memcg are stable under us. * Then we can use css_is_ancestor without taking care of RCU. */ if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg) && !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg)) return 0; return autoremove_wake_function(wait, mode, sync, arg); } static void memcg_wakeup_oom(struct mem_cgroup *memcg) { atomic_inc(&memcg->oom_wakeups); /* for filtering, pass "memcg" as argument. */ __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); } static void memcg_oom_recover(struct mem_cgroup *memcg) { if (memcg && atomic_read(&memcg->under_oom)) memcg_wakeup_oom(memcg); } /* * try to call OOM killer */ static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) { bool locked; int wakeups; if (!current->memcg_oom.may_oom) return; current->memcg_oom.in_memcg_oom = 1; /* * As with any blocking lock, a contender needs to start * listening for wakeups before attempting the trylock, * otherwise it can miss the wakeup from the unlock and sleep * indefinitely. This is just open-coded because our locking * is so particular to memcg hierarchies. */ wakeups = atomic_read(&memcg->oom_wakeups); mem_cgroup_mark_under_oom(memcg); locked = mem_cgroup_oom_trylock(memcg); if (locked) mem_cgroup_oom_notify(memcg); if (locked && !memcg->oom_kill_disable) { mem_cgroup_unmark_under_oom(memcg); mem_cgroup_out_of_memory(memcg, mask, order); mem_cgroup_oom_unlock(memcg); /* * There is no guarantee that an OOM-lock contender * sees the wakeups triggered by the OOM kill * uncharges. Wake any sleepers explicitely. */ memcg_oom_recover(memcg); } else { /* * A system call can just return -ENOMEM, but if this * is a page fault and somebody else is handling the * OOM already, we need to sleep on the OOM waitqueue * for this memcg until the situation is resolved. * Which can take some time because it might be * handled by a userspace task. * * However, this is the charge context, which means * that we may sit on a large call stack and hold * various filesystem locks, the mmap_sem etc. and we * don't want the OOM handler to deadlock on them * while we sit here and wait. Store the current OOM * context in the task_struct, then return -ENOMEM. * At the end of the page fault handler, with the * stack unwound, pagefault_out_of_memory() will check * back with us by calling * mem_cgroup_oom_synchronize(), possibly putting the * task to sleep. */ current->memcg_oom.oom_locked = locked; current->memcg_oom.wakeups = wakeups; css_get(&memcg->css); current->memcg_oom.wait_on_memcg = memcg; } } /** * mem_cgroup_oom_synchronize - complete memcg OOM handling * * This has to be called at the end of a page fault if the the memcg * OOM handler was enabled and the fault is returning %VM_FAULT_OOM. * * Memcg supports userspace OOM handling, so failed allocations must * sleep on a waitqueue until the userspace task resolves the * situation. Sleeping directly in the charge context with all kinds * of locks held is not a good idea, instead we remember an OOM state * in the task and mem_cgroup_oom_synchronize() has to be called at * the end of the page fault to put the task to sleep and clean up the * OOM state. * * Returns %true if an ongoing memcg OOM situation was detected and * finalized, %false otherwise. */ bool mem_cgroup_oom_synchronize(void) { struct oom_wait_info owait; struct mem_cgroup *memcg; /* OOM is global, do not handle */ if (!current->memcg_oom.in_memcg_oom) return false; /* * We invoked the OOM killer but there is a chance that a kill * did not free up any charges. Everybody else might already * be sleeping, so restart the fault and keep the rampage * going until some charges are released. */ memcg = current->memcg_oom.wait_on_memcg; if (!memcg) goto out; if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current)) goto out_memcg; owait.memcg = memcg; owait.wait.flags = 0; owait.wait.func = memcg_oom_wake_function; owait.wait.private = current; INIT_LIST_HEAD(&owait.wait.task_list); prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); /* Only sleep if we didn't miss any wakeups since OOM */ if (atomic_read(&memcg->oom_wakeups) == current->memcg_oom.wakeups) schedule(); finish_wait(&memcg_oom_waitq, &owait.wait); out_memcg: mem_cgroup_unmark_under_oom(memcg); if (current->memcg_oom.oom_locked) { mem_cgroup_oom_unlock(memcg); /* * There is no guarantee that an OOM-lock contender * sees the wakeups triggered by the OOM kill * uncharges. Wake any sleepers explicitely. */ memcg_oom_recover(memcg); } css_put(&memcg->css); current->memcg_oom.wait_on_memcg = NULL; out: current->memcg_oom.in_memcg_oom = 0; return true; } /* * Currently used to update mapped file statistics, but the routine can be * generalized to update other statistics as well. * * Notes: Race condition * * We usually use page_cgroup_lock() for accessing page_cgroup member but * it tends to be costly. But considering some conditions, we doesn't need * to do so _always_. * * Considering "charge", lock_page_cgroup() is not required because all * file-stat operations happen after a page is attached to radix-tree. There * are no race with "charge". * * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even * if there are race with "uncharge". Statistics itself is properly handled * by flags. * * Considering "move", this is an only case we see a race. To make the race * small, we check mm->moving_account and detect there are possibility of race * If there is, we take a lock. */ void __mem_cgroup_begin_update_page_stat(struct page *page, bool *locked, unsigned long *flags) { struct mem_cgroup *memcg; struct page_cgroup *pc; pc = lookup_page_cgroup(page); again: memcg = pc->mem_cgroup; if (unlikely(!memcg || !PageCgroupUsed(pc))) return; /* * If this memory cgroup is not under account moving, we don't * need to take move_lock_mem_cgroup(). Because we already hold * rcu_read_lock(), any calls to move_account will be delayed until * rcu_read_unlock() if mem_cgroup_stolen() == true. */ if (!mem_cgroup_stolen(memcg)) return; move_lock_mem_cgroup(memcg, flags); if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) { move_unlock_mem_cgroup(memcg, flags); goto again; } *locked = true; } void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags) { struct page_cgroup *pc = lookup_page_cgroup(page); /* * It's guaranteed that pc->mem_cgroup never changes while * lock is held because a routine modifies pc->mem_cgroup * should take move_lock_mem_cgroup(). */ move_unlock_mem_cgroup(pc->mem_cgroup, flags); } void mem_cgroup_update_page_stat(struct page *page, enum mem_cgroup_stat_index idx, int val) { struct mem_cgroup *memcg; struct page_cgroup *pc = lookup_page_cgroup(page); unsigned long uninitialized_var(flags); if (mem_cgroup_disabled()) return; VM_BUG_ON(!rcu_read_lock_held()); memcg = pc->mem_cgroup; if (unlikely(!memcg || !PageCgroupUsed(pc))) return; this_cpu_add(memcg->stat->count[idx], val); } /* * size of first charge trial. "32" comes from vmscan.c's magic value. * TODO: maybe necessary to use big numbers in big irons. */ #define CHARGE_BATCH 32U struct memcg_stock_pcp { struct mem_cgroup *cached; /* this never be root cgroup */ unsigned int nr_pages; struct work_struct work; unsigned long flags; #define FLUSHING_CACHED_CHARGE 0 }; static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); static DEFINE_MUTEX(percpu_charge_mutex); /** * consume_stock: Try to consume stocked charge on this cpu. * @memcg: memcg to consume from. * @nr_pages: how many pages to charge. * * The charges will only happen if @memcg matches the current cpu's memcg * stock, and at least @nr_pages are available in that stock. Failure to * service an allocation will refill the stock. * * returns true if successful, false otherwise. */ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) { struct memcg_stock_pcp *stock; bool ret = true; if (nr_pages > CHARGE_BATCH) return false; stock = &get_cpu_var(memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) stock->nr_pages -= nr_pages; else /* need to call res_counter_charge */ ret = false; put_cpu_var(memcg_stock); return ret; } /* * Returns stocks cached in percpu to res_counter and reset cached information. */ static void drain_stock(struct memcg_stock_pcp *stock) { struct mem_cgroup *old = stock->cached; if (stock->nr_pages) { unsigned long bytes = stock->nr_pages * PAGE_SIZE; res_counter_uncharge(&old->res, bytes); if (do_swap_account) res_counter_uncharge(&old->memsw, bytes); stock->nr_pages = 0; } stock->cached = NULL; } /* * This must be called under preempt disabled or must be called by * a thread which is pinned to local cpu. */ static void drain_local_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); } static void __init memcg_stock_init(void) { int cpu; for_each_possible_cpu(cpu) { struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); INIT_WORK(&stock->work, drain_local_stock); } } /* * Cache charges(val) which is from res_counter, to local per_cpu area. * This will be consumed by consume_stock() function, later. */ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) { struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); stock->cached = memcg; } stock->nr_pages += nr_pages; put_cpu_var(memcg_stock); } /* * Drains all per-CPU charge caches for given root_memcg resp. subtree * of the hierarchy under it. sync flag says whether we should block * until the work is done. */ static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync) { int cpu, curcpu; /* Notify other cpus that system-wide "drain" is running */ get_online_cpus(); curcpu = get_cpu(); for_each_online_cpu(cpu) { struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); struct mem_cgroup *memcg; memcg = stock->cached; if (!memcg || !stock->nr_pages) continue; if (!mem_cgroup_same_or_subtree(root_memcg, memcg)) continue; if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) { if (cpu == curcpu) drain_local_stock(&stock->work); else schedule_work_on(cpu, &stock->work); } } put_cpu(); if (!sync) goto out; for_each_online_cpu(cpu) { struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) flush_work(&stock->work); } out: put_online_cpus(); } /* * Tries to drain stocked charges in other cpus. This function is asynchronous * and just put a work per cpu for draining localy on each cpu. Caller can * expects some charges will be back to res_counter later but cannot wait for * it. */ static void drain_all_stock_async(struct mem_cgroup *root_memcg) { /* * If someone calls draining, avoid adding more kworker runs. */ if (!mutex_trylock(&percpu_charge_mutex)) return; drain_all_stock(root_memcg, false); mutex_unlock(&percpu_charge_mutex); } /* This is a synchronous drain interface. */ static void drain_all_stock_sync(struct mem_cgroup *root_memcg) { /* called when force_empty is called */ mutex_lock(&percpu_charge_mutex); drain_all_stock(root_memcg, true); mutex_unlock(&percpu_charge_mutex); } /* * This function drains percpu counter value from DEAD cpu and * move it to local cpu. Note that this function can be preempted. */ static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu) { int i; spin_lock(&memcg->pcp_counter_lock); for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { long x = per_cpu(memcg->stat->count[i], cpu); per_cpu(memcg->stat->count[i], cpu) = 0; memcg->nocpu_base.count[i] += x; } for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) { unsigned long x = per_cpu(memcg->stat->events[i], cpu); per_cpu(memcg->stat->events[i], cpu) = 0; memcg->nocpu_base.events[i] += x; } spin_unlock(&memcg->pcp_counter_lock); } static int memcg_cpu_hotplug_callback(struct notifier_block *nb, unsigned long action, void *hcpu) { int cpu = (unsigned long)hcpu; struct memcg_stock_pcp *stock; struct mem_cgroup *iter; if (action == CPU_ONLINE) return NOTIFY_OK; if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) return NOTIFY_OK; for_each_mem_cgroup(iter) mem_cgroup_drain_pcp_counter(iter, cpu); stock = &per_cpu(memcg_stock, cpu); drain_stock(stock); return NOTIFY_OK; } /* See __mem_cgroup_try_charge() for details */ enum { CHARGE_OK, /* success */ CHARGE_RETRY, /* need to retry but retry is not bad */ CHARGE_NOMEM, /* we can't do more. return -ENOMEM */ CHARGE_WOULDBLOCK, /* GFP_WAIT wasn't set and no enough res. */ }; static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages, unsigned int min_pages, bool invoke_oom) { unsigned long csize = nr_pages * PAGE_SIZE; struct mem_cgroup *mem_over_limit; struct res_counter *fail_res; unsigned long flags = 0; int ret; ret = res_counter_charge(&memcg->res, csize, &fail_res); if (likely(!ret)) { if (!do_swap_account) return CHARGE_OK; ret = res_counter_charge(&memcg->memsw, csize, &fail_res); if (likely(!ret)) return CHARGE_OK; res_counter_uncharge(&memcg->res, csize); mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw); flags |= MEM_CGROUP_RECLAIM_NOSWAP; } else mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); /* * Never reclaim on behalf of optional batching, retry with a * single page instead. */ if (nr_pages > min_pages) return CHARGE_RETRY; if (!(gfp_mask & __GFP_WAIT)) return CHARGE_WOULDBLOCK; if (gfp_mask & __GFP_NORETRY) return CHARGE_NOMEM; ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) return CHARGE_RETRY; /* * Even though the limit is exceeded at this point, reclaim * may have been able to free some pages. Retry the charge * before killing the task. * * Only for regular pages, though: huge pages are rather * unlikely to succeed so close to the limit, and we fall back * to regular pages anyway in case of failure. */ if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret) return CHARGE_RETRY; /* * At task move, charge accounts can be doubly counted. So, it's * better to wait until the end of task_move if something is going on. */ if (mem_cgroup_wait_acct_move(mem_over_limit)) return CHARGE_RETRY; if (invoke_oom) mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize)); return CHARGE_NOMEM; } /* * __mem_cgroup_try_charge() does * 1. detect memcg to be charged against from passed *mm and *ptr, * 2. update res_counter * 3. call memory reclaim if necessary. * * In some special case, if the task is fatal, fatal_signal_pending() or * has TIF_MEMDIE, this function returns -EINTR while writing root_mem_cgroup * to *ptr. There are two reasons for this. 1: fatal threads should quit as soon * as possible without any hazards. 2: all pages should have a valid * pc->mem_cgroup. If mm is NULL and the caller doesn't pass a valid memcg * pointer, that is treated as a charge to root_mem_cgroup. * * So __mem_cgroup_try_charge() will return * 0 ... on success, filling *ptr with a valid memcg pointer. * -ENOMEM ... charge failure because of resource limits. * -EINTR ... if thread is fatal. *ptr is filled with root_mem_cgroup. * * Unlike the exported interface, an "oom" parameter is added. if oom==true, * the oom-killer can be invoked. */ static int __mem_cgroup_try_charge(struct mm_struct *mm, gfp_t gfp_mask, unsigned int nr_pages, struct mem_cgroup **ptr, bool oom) { unsigned int batch = max(CHARGE_BATCH, nr_pages); int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; struct mem_cgroup *memcg = NULL; int ret; /* * Unlike gloval-vm's OOM-kill, we're not in memory shortage * in system level. So, allow to go ahead dying process in addition to * MEMDIE process. */ if (unlikely(test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))) goto bypass; /* * We always charge the cgroup the mm_struct belongs to. * The mm_struct's mem_cgroup changes on task migration if the * thread group leader migrates. It's possible that mm is not * set, if so charge the root memcg (happens for pagecache usage). */ if (!*ptr && !mm) *ptr = root_mem_cgroup; again: if (*ptr) { /* css should be a valid one */ memcg = *ptr; if (mem_cgroup_is_root(memcg)) goto done; if (consume_stock(memcg, nr_pages)) goto done; css_get(&memcg->css); } else { struct task_struct *p; rcu_read_lock(); p = rcu_dereference(mm->owner); /* * Because we don't have task_lock(), "p" can exit. * In that case, "memcg" can point to root or p can be NULL with * race with swapoff. Then, we have small risk of mis-accouning. * But such kind of mis-account by race always happens because * we don't have cgroup_mutex(). It's overkill and we allo that * small race, here. * (*) swapoff at el will charge against mm-struct not against * task-struct. So, mm->owner can be NULL. */ memcg = mem_cgroup_from_task(p); if (!memcg) memcg = root_mem_cgroup; if (mem_cgroup_is_root(memcg)) { rcu_read_unlock(); goto done; } if (consume_stock(memcg, nr_pages)) { /* * It seems dagerous to access memcg without css_get(). * But considering how consume_stok works, it's not * necessary. If consume_stock success, some charges * from this memcg are cached on this cpu. So, we * don't need to call css_get()/css_tryget() before * calling consume_stock(). */ rcu_read_unlock(); goto done; } /* after here, we may be blocked. we need to get refcnt */ if (!css_tryget(&memcg->css)) { rcu_read_unlock(); goto again; } rcu_read_unlock(); } do { bool invoke_oom = oom && !nr_oom_retries; /* If killed, bypass charge */ if (fatal_signal_pending(current)) { css_put(&memcg->css); goto bypass; } ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, nr_pages, invoke_oom); switch (ret) { case CHARGE_OK: break; case CHARGE_RETRY: /* not in OOM situation but retry */ batch = nr_pages; css_put(&memcg->css); memcg = NULL; goto again; case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */ css_put(&memcg->css); goto nomem; case CHARGE_NOMEM: /* OOM routine works */ if (!oom || invoke_oom) { css_put(&memcg->css); goto nomem; } nr_oom_retries--; break; } } while (ret != CHARGE_OK); if (batch > nr_pages) refill_stock(memcg, batch - nr_pages); css_put(&memcg->css); done: *ptr = memcg; return 0; nomem: *ptr = NULL; return -ENOMEM; bypass: *ptr = root_mem_cgroup; return -EINTR; } /* * Somemtimes we have to undo a charge we got by try_charge(). * This function is for that and do uncharge, put css's refcnt. * gotten by try_charge(). */ static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) { if (!mem_cgroup_is_root(memcg)) { unsigned long bytes = nr_pages * PAGE_SIZE; res_counter_uncharge(&memcg->res, bytes); if (do_swap_account) res_counter_uncharge(&memcg->memsw, bytes); } } /* * Cancel chrages in this cgroup....doesn't propagate to parent cgroup. * This is useful when moving usage to parent cgroup. */ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg, unsigned int nr_pages) { unsigned long bytes = nr_pages * PAGE_SIZE; if (mem_cgroup_is_root(memcg)) return; res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes); if (do_swap_account) res_counter_uncharge_until(&memcg->memsw, memcg->memsw.parent, bytes); } /* * A helper function to get mem_cgroup from ID. must be called under * rcu_read_lock(). The caller is responsible for calling css_tryget if * the mem_cgroup is used for charging. (dropping refcnt from swap can be * called against removed memcg.) */ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) { /* ID 0 is unused ID */ if (!id) return NULL; return mem_cgroup_from_id(id); } struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) { struct mem_cgroup *memcg = NULL; struct page_cgroup *pc; unsigned short id; swp_entry_t ent; VM_BUG_ON(!PageLocked(page)); pc = lookup_page_cgroup(page); lock_page_cgroup(pc); if (PageCgroupUsed(pc)) { memcg = pc->mem_cgroup; if (memcg && !css_tryget(&memcg->css)) memcg = NULL; } else if (PageSwapCache(page)) { ent.val = page_private(page); id = lookup_swap_cgroup_id(ent); rcu_read_lock(); memcg = mem_cgroup_lookup(id); if (memcg && !css_tryget(&memcg->css)) memcg = NULL; rcu_read_unlock(); } unlock_page_cgroup(pc); return memcg; } static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, struct page *page, unsigned int nr_pages, enum charge_type ctype, bool lrucare) { struct page_cgroup *pc = lookup_page_cgroup(page); struct zone *uninitialized_var(zone); struct lruvec *lruvec; bool was_on_lru = false; bool anon; lock_page_cgroup(pc); VM_BUG_ON(PageCgroupUsed(pc)); /* * we don't need page_cgroup_lock about tail pages, becase they are not * accessed by any other context at this point. */ /* * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page * may already be on some other mem_cgroup's LRU. Take care of it. */ if (lrucare) { zone = page_zone(page); spin_lock_irq(&zone->lru_lock); if (PageLRU(page)) { lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup); ClearPageLRU(page); del_page_from_lru_list(page, lruvec, page_lru(page)); was_on_lru = true; } } pc->mem_cgroup = memcg; /* * We access a page_cgroup asynchronously without lock_page_cgroup(). * Especially when a page_cgroup is taken from a page, pc->mem_cgroup * is accessed after testing USED bit. To make pc->mem_cgroup visible * before USED bit, we need memory barrier here. * See mem_cgroup_add_lru_list(), etc. */ smp_wmb(); SetPageCgroupUsed(pc); if (lrucare) { if (was_on_lru) { lruvec = mem_cgroup_zone_lruvec(zone, pc->mem_cgroup); VM_BUG_ON(PageLRU(page)); SetPageLRU(page); add_page_to_lru_list(page, lruvec, page_lru(page)); } spin_unlock_irq(&zone->lru_lock); } if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON) anon = true; else anon = false; mem_cgroup_charge_statistics(memcg, page, anon, nr_pages); unlock_page_cgroup(pc); /* * "charge_statistics" updated event counter. */ memcg_check_events(memcg, page); } static DEFINE_MUTEX(set_limit_mutex); #ifdef CONFIG_MEMCG_KMEM static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg) { return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) && (memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK); } /* * This is a bit cumbersome, but it is rarely used and avoids a backpointer * in the memcg_cache_params struct. */ static struct kmem_cache *memcg_params_to_cache(struct memcg_cache_params *p) { struct kmem_cache *cachep; VM_BUG_ON(p->is_root_cache); cachep = p->root_cache; return cachep->memcg_params->memcg_caches[memcg_cache_id(p->memcg)]; } #ifdef CONFIG_SLABINFO static int mem_cgroup_slabinfo_read(struct cgroup_subsys_state *css, struct cftype *cft, struct seq_file *m) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct memcg_cache_params *params; if (!memcg_can_account_kmem(memcg)) return -EIO; print_slabinfo_header(m); mutex_lock(&memcg->slab_caches_mutex); list_for_each_entry(params, &memcg->memcg_slab_caches, list) cache_show(memcg_params_to_cache(params), m); mutex_unlock(&memcg->slab_caches_mutex); return 0; } #endif static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size) { struct res_counter *fail_res; struct mem_cgroup *_memcg; int ret = 0; bool may_oom; ret = res_counter_charge(&memcg->kmem, size, &fail_res); if (ret) return ret; /* * Conditions under which we can wait for the oom_killer. Those are * the same conditions tested by the core page allocator */ may_oom = (gfp & __GFP_FS) && !(gfp & __GFP_NORETRY); _memcg = memcg; ret = __mem_cgroup_try_charge(NULL, gfp, size >> PAGE_SHIFT, &_memcg, may_oom); if (ret == -EINTR) { /* * __mem_cgroup_try_charge() chosed to bypass to root due to * OOM kill or fatal signal. Since our only options are to * either fail the allocation or charge it to this cgroup, do * it as a temporary condition. But we can't fail. From a * kmem/slab perspective, the cache has already been selected, * by mem_cgroup_kmem_get_cache(), so it is too late to change * our minds. * * This condition will only trigger if the task entered * memcg_charge_kmem in a sane state, but was OOM-killed during * __mem_cgroup_try_charge() above. Tasks that were already * dying when the allocation triggers should have been already * directed to the root cgroup in memcontrol.h */ res_counter_charge_nofail(&memcg->res, size, &fail_res); if (do_swap_account) res_counter_charge_nofail(&memcg->memsw, size, &fail_res); ret = 0; } else if (ret) res_counter_uncharge(&memcg->kmem, size); return ret; } static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size) { res_counter_uncharge(&memcg->res, size); if (do_swap_account) res_counter_uncharge(&memcg->memsw, size); /* Not down to 0 */ if (res_counter_uncharge(&memcg->kmem, size)) return; /* * Releases a reference taken in kmem_cgroup_css_offline in case * this last uncharge is racing with the offlining code or it is * outliving the memcg existence. * * The memory barrier imposed by test&clear is paired with the * explicit one in memcg_kmem_mark_dead(). */ if (memcg_kmem_test_and_clear_dead(memcg)) css_put(&memcg->css); } void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep) { if (!memcg) return; mutex_lock(&memcg->slab_caches_mutex); list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches); mutex_unlock(&memcg->slab_caches_mutex); } /* * helper for acessing 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. */ int memcg_cache_id(struct mem_cgroup *memcg) { return memcg ? memcg->kmemcg_id : -1; } /* * This ends up being protected by the set_limit mutex, during normal * operation, because that is its main call site. * * But when we create a new cache, we can call this as well if its parent * is kmem-limited. That will have to hold set_limit_mutex as well. */ int memcg_update_cache_sizes(struct mem_cgroup *memcg) { int num, ret; num = ida_simple_get(&kmem_limited_groups, 0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL); if (num < 0) return num; /* * After this point, kmem_accounted (that we test atomically in * the beginning of this conditional), is no longer 0. This * guarantees only one process will set the following boolean * to true. We don't need test_and_set because we're protected * by the set_limit_mutex anyway. */ memcg_kmem_set_activated(memcg); ret = memcg_update_all_caches(num+1); if (ret) { ida_simple_remove(&kmem_limited_groups, num); memcg_kmem_clear_activated(memcg); return ret; } memcg->kmemcg_id = num; INIT_LIST_HEAD(&memcg->memcg_slab_caches); mutex_init(&memcg->slab_caches_mutex); return 0; } static size_t memcg_caches_array_size(int num_groups) { ssize_t size; if (num_groups <= 0) return 0; size = 2 * num_groups; if (size < MEMCG_CACHES_MIN_SIZE) size = MEMCG_CACHES_MIN_SIZE; else if (size > MEMCG_CACHES_MAX_SIZE) size = MEMCG_CACHES_MAX_SIZE; return size; } /* * We should update the current array size iff all caches updates succeed. This * can only be done from the slab side. The slab mutex needs to be held when * calling this. */ void memcg_update_array_size(int num) { if (num > memcg_limited_groups_array_size) memcg_limited_groups_array_size = memcg_caches_array_size(num); } static void kmem_cache_destroy_work_func(struct work_struct *w); int memcg_update_cache_size(struct kmem_cache *s, int num_groups) { struct memcg_cache_params *cur_params = s->memcg_params; VM_BUG_ON(s->memcg_params && !s->memcg_params->is_root_cache); if (num_groups > memcg_limited_groups_array_size) { int i; ssize_t size = memcg_caches_array_size(num_groups); size *= sizeof(void *); size += offsetof(struct memcg_cache_params, memcg_caches); s->memcg_params = kzalloc(size, GFP_KERNEL); if (!s->memcg_params) { s->memcg_params = cur_params; return -ENOMEM; } s->memcg_params->is_root_cache = true; /* * There is the chance it will be bigger than * memcg_limited_groups_array_size, if we failed an allocation * in a cache, in which case all caches updated before it, will * have a bigger array. * * But if that is the case, the data after * memcg_limited_groups_array_size is certainly unused */ for (i = 0; i < memcg_limited_groups_array_size; i++) { if (!cur_params->memcg_caches[i]) continue; s->memcg_params->memcg_caches[i] = cur_params->memcg_caches[i]; } /* * Ideally, we would wait until all caches succeed, and only * then free the old one. But this is not worth the extra * pointer per-cache we'd have to have for this. * * It is not a big deal if some caches are left with a size * bigger than the others. And all updates will reset this * anyway. */ kfree(cur_params); } return 0; } int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s, struct kmem_cache *root_cache) { size_t size; if (!memcg_kmem_enabled()) return 0; if (!memcg) { size = offsetof(struct memcg_cache_params, memcg_caches); size += memcg_limited_groups_array_size * sizeof(void *); } else size = sizeof(struct memcg_cache_params); s->memcg_params = kzalloc(size, GFP_KERNEL); if (!s->memcg_params) return -ENOMEM; if (memcg) { s->memcg_params->memcg = memcg; s->memcg_params->root_cache = root_cache; INIT_WORK(&s->memcg_params->destroy, kmem_cache_destroy_work_func); } else s->memcg_params->is_root_cache = true; return 0; } void memcg_release_cache(struct kmem_cache *s) { struct kmem_cache *root; struct mem_cgroup *memcg; int id; /* * This happens, for instance, when a root cache goes away before we * add any memcg. */ if (!s->memcg_params) return; if (s->memcg_params->is_root_cache) goto out; memcg = s->memcg_params->memcg; id = memcg_cache_id(memcg); root = s->memcg_params->root_cache; root->memcg_params->memcg_caches[id] = NULL; mutex_lock(&memcg->slab_caches_mutex); list_del(&s->memcg_params->list); mutex_unlock(&memcg->slab_caches_mutex); css_put(&memcg->css); out: kfree(s->memcg_params); } /* * During the creation a new cache, we need to disable our accounting mechanism * altogether. This is true even if we are not creating, but rather just * enqueing new caches to be created. * * This is because that process will trigger allocations; some visible, like * explicit kmallocs to auxiliary data structures, name strings and internal * cache structures; some well concealed, like INIT_WORK() that can allocate * objects during debug. * * If any allocation happens during memcg_kmem_get_cache, we will recurse back * to it. This may not be a bounded recursion: since the first cache creation * failed to complete (waiting on the allocation), we'll just try to create the * cache again, failing at the same point. * * memcg_kmem_get_cache is prepared to abort after seeing a positive count of * memcg_kmem_skip_account. So we enclose anything that might allocate memory * inside the following two functions. */ static inline void memcg_stop_kmem_account(void) { VM_BUG_ON(!current->mm); current->memcg_kmem_skip_account++; } static inline void memcg_resume_kmem_account(void) { VM_BUG_ON(!current->mm); current->memcg_kmem_skip_account--; } static void kmem_cache_destroy_work_func(struct work_struct *w) { struct kmem_cache *cachep; struct memcg_cache_params *p; p = container_of(w, struct memcg_cache_params, destroy); cachep = memcg_params_to_cache(p); /* * If we get down to 0 after shrink, we could delete right away. * However, memcg_release_pages() already puts us back in the workqueue * in that case. If we proceed deleting, we'll get a dangling * reference, and removing the object from the workqueue in that case * is unnecessary complication. We are not a fast path. * * Note that this case is fundamentally different from racing with * shrink_slab(): if memcg_cgroup_destroy_cache() is called in * kmem_cache_shrink, not only we would be reinserting a dead cache * into the queue, but doing so from inside the worker racing to * destroy it. * * So if we aren't down to zero, we'll just schedule a worker and try * again */ if (atomic_read(&cachep->memcg_params->nr_pages) != 0) { kmem_cache_shrink(cachep); if (atomic_read(&cachep->memcg_params->nr_pages) == 0) return; } else kmem_cache_destroy(cachep); } void mem_cgroup_destroy_cache(struct kmem_cache *cachep) { if (!cachep->memcg_params->dead) return; /* * There are many ways in which we can get here. * * We can get to a memory-pressure situation while the delayed work is * still pending to run. The vmscan shrinkers can then release all * cache memory and get us to destruction. If this is the case, we'll * be executed twice, which is a bug (the second time will execute over * bogus data). In this case, cancelling the work should be fine. * * But we can also get here from the worker itself, if * kmem_cache_shrink is enough to shake all the remaining objects and * get the page count to 0. In this case, we'll deadlock if we try to * cancel the work (the worker runs with an internal lock held, which * is the same lock we would hold for cancel_work_sync().) * * Since we can't possibly know who got us here, just refrain from * running if there is already work pending */ if (work_pending(&cachep->memcg_params->destroy)) return; /* * We have to defer the actual destroying to a workqueue, because * we might currently be in a context that cannot sleep. */ schedule_work(&cachep->memcg_params->destroy); } /* * This lock protects updaters, not readers. We want readers to be as fast as * they can, and they will either see NULL or a valid cache value. Our model * allow them to see NULL, in which case the root memcg will be selected. * * We need this lock because multiple allocations to the same cache from a non * will span more than one worker. Only one of them can create the cache. */ static DEFINE_MUTEX(memcg_cache_mutex); /* * Called with memcg_cache_mutex held */ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg, struct kmem_cache *s) { struct kmem_cache *new; static char *tmp_name = NULL; lockdep_assert_held(&memcg_cache_mutex); /* * kmem_cache_create_memcg duplicates the given name and * cgroup_name for this name requires RCU context. * This static temporary buffer is used to prevent from * pointless shortliving allocation. */ if (!tmp_name) { tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); if (!tmp_name) return NULL; } rcu_read_lock(); snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name, memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup)); rcu_read_unlock(); new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align, (s->flags & ~SLAB_PANIC), s->ctor, s); if (new) new->allocflags |= __GFP_KMEMCG; return new; } static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, struct kmem_cache *cachep) { struct kmem_cache *new_cachep; int idx; BUG_ON(!memcg_can_account_kmem(memcg)); idx = memcg_cache_id(memcg); mutex_lock(&memcg_cache_mutex); new_cachep = cachep->memcg_params->memcg_caches[idx]; if (new_cachep) { css_put(&memcg->css); goto out; } new_cachep = kmem_cache_dup(memcg, cachep); if (new_cachep == NULL) { new_cachep = cachep; css_put(&memcg->css); goto out; } atomic_set(&new_cachep->memcg_params->nr_pages , 0); cachep->memcg_params->memcg_caches[idx] = new_cachep; /* * the readers won't lock, make sure everybody sees the updated value, * so they won't put stuff in the queue again for no reason */ wmb(); out: mutex_unlock(&memcg_cache_mutex); return new_cachep; } void kmem_cache_destroy_memcg_children(struct kmem_cache *s) { struct kmem_cache *c; int i; if (!s->memcg_params) return; if (!s->memcg_params->is_root_cache) return; /* * If the cache is being destroyed, we trust that there is no one else * requesting objects from it. Even if there are, the sanity checks in * kmem_cache_destroy should caught this ill-case. * * Still, we don't want anyone else freeing memcg_caches under our * noses, which can happen if a new memcg comes to life. As usual, * we'll take the set_limit_mutex to protect ourselves against this. */ mutex_lock(&set_limit_mutex); for (i = 0; i < memcg_limited_groups_array_size; i++) { c = s->memcg_params->memcg_caches[i]; if (!c) continue; /* * We will now manually delete the caches, so to avoid races * we need to cancel all pending destruction workers and * proceed with destruction ourselves. * * kmem_cache_destroy() will call kmem_cache_shrink internally, * and that could spawn the workers again: it is likely that * the cache still have active pages until this very moment. * This would lead us back to mem_cgroup_destroy_cache. * * But that will not execute at all if the "dead" flag is not * set, so flip it down to guarantee we are in control. */ c->memcg_params->dead = false; cancel_work_sync(&c->memcg_params->destroy); kmem_cache_destroy(c); } mutex_unlock(&set_limit_mutex); } struct create_work { struct mem_cgroup *memcg; struct kmem_cache *cachep; struct work_struct work; }; static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg) { struct kmem_cache *cachep; struct memcg_cache_params *params; if (!memcg_kmem_is_active(memcg)) return; mutex_lock(&memcg->slab_caches_mutex); list_for_each_entry(params, &memcg->memcg_slab_caches, list) { cachep = memcg_params_to_cache(params); cachep->memcg_params->dead = true; schedule_work(&cachep->memcg_params->destroy); } mutex_unlock(&memcg->slab_caches_mutex); } static void memcg_create_cache_work_func(struct work_struct *w) { struct create_work *cw; cw = container_of(w, struct create_work, work); memcg_create_kmem_cache(cw->memcg, cw->cachep); kfree(cw); } /* * Enqueue the creation of a per-memcg kmem_cache. */ static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg, struct kmem_cache *cachep) { struct create_work *cw; cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT); if (cw == NULL) { css_put(&memcg->css); return; } cw->memcg = memcg; cw->cachep = cachep; INIT_WORK(&cw->work, memcg_create_cache_work_func); schedule_work(&cw->work); } static void memcg_create_cache_enqueue(struct mem_cgroup *memcg, struct kmem_cache *cachep) { /* * We need to stop accounting when we kmalloc, because if the * corresponding kmalloc cache is not yet created, the first allocation * in __memcg_create_cache_enqueue will recurse. * * However, it is better to enclose the whole function. Depending on * the debugging options enabled, INIT_WORK(), for instance, can * trigger an allocation. This too, will make us recurse. Because at * this point we can't allow ourselves back into memcg_kmem_get_cache, * the safest choice is to do it like this, wrapping the whole function. */ memcg_stop_kmem_account(); __memcg_create_cache_enqueue(memcg, cachep); memcg_resume_kmem_account(); } /* * Return the kmem_cache we're supposed to use for a slab allocation. * We try to use the current memcg's version of the cache. * * If the cache does not exist yet, if we are the first user of it, * we either create it immediately, if possible, or create it asynchronously * in a workqueue. * In the latter case, we will let the current allocation go through with * the original cache. * * Can't be called in interrupt context or from kernel threads. * This function needs to be called with rcu_read_lock() held. */ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp) { struct mem_cgroup *memcg; int idx; VM_BUG_ON(!cachep->memcg_params); VM_BUG_ON(!cachep->memcg_params->is_root_cache); if (!current->mm || current->memcg_kmem_skip_account) return cachep; rcu_read_lock(); memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner)); if (!memcg_can_account_kmem(memcg)) goto out; idx = memcg_cache_id(memcg); /* * barrier to mare sure we're always seeing the up to date value. The * code updating memcg_caches will issue a write barrier to match this. */ read_barrier_depends(); if (likely(cachep->memcg_params->memcg_caches[idx])) { cachep = cachep->memcg_params->memcg_caches[idx]; goto out; } /* The corresponding put will be done in the workqueue. */ if (!css_tryget(&memcg->css)) goto out; rcu_read_unlock(); /* * If we are in a safe context (can wait, and not in interrupt * context), we could be be predictable and return right away. * This would guarantee that the allocation being performed * already belongs in the new cache. * * However, there are some clashes that can arrive from locking. * For instance, because we acquire the slab_mutex while doing * kmem_cache_dup, this means no further allocation could happen * with the slab_mutex held. * * Also, because cache creation issue get_online_cpus(), this * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex, * that ends up reversed during cpu hotplug. (cpuset allocates * a bunch of GFP_KERNEL memory during cpuup). Due to all that, * better to defer everything. */ memcg_create_cache_enqueue(memcg, cachep); return cachep; out: rcu_read_unlock(); return cachep; } EXPORT_SYMBOL(__memcg_kmem_get_cache); /* * We need to verify if the allocation against current->mm->owner's memcg is * possible for the given order. But the page is not allocated yet, so we'll * need a further commit step to do the final arrangements. * * It is possible for the task to switch cgroups in this mean time, so at * commit time, we can't rely on task conversion any longer. We'll then use * the handle argument to return to the caller which cgroup we should commit * against. We could also return the memcg directly and avoid the pointer * passing, but a boolean return value gives better semantics considering * the compiled-out case as well. * * Returning true means the allocation is possible. */ bool __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) { struct mem_cgroup *memcg; int ret; *_memcg = NULL; /* * Disabling accounting is only relevant for some specific memcg * internal allocations. Therefore we would initially not have such * check here, since direct calls to the page allocator that are marked * with GFP_KMEMCG only happen outside memcg core. We are mostly * concerned with cache allocations, and by having this test at * memcg_kmem_get_cache, we are already able to relay the allocation to * the root cache and bypass the memcg cache altogether. * * There is one exception, though: the SLUB allocator does not create * large order caches, but rather service large kmallocs directly from * the page allocator. Therefore, the following sequence when backed by * the SLUB allocator: * * memcg_stop_kmem_account(); * kmalloc() * memcg_resume_kmem_account(); * * would effectively ignore the fact that we should skip accounting, * since it will drive us directly to this function without passing * through the cache selector memcg_kmem_get_cache. Such large * allocations are extremely rare but can happen, for instance, for the * cache arrays. We bring this test here. */ if (!current->mm || current->memcg_kmem_skip_account) return true; memcg = try_get_mem_cgroup_from_mm(current->mm); /* * very rare case described in mem_cgroup_from_task. Unfortunately there * isn't much we can do without complicating this too much, and it would * be gfp-dependent anyway. Just let it go */ if (unlikely(!memcg)) return true; if (!memcg_can_account_kmem(memcg)) { css_put(&memcg->css); return true; } ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order); if (!ret) *_memcg = memcg; css_put(&memcg->css); return (ret == 0); } void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order) { struct page_cgroup *pc; VM_BUG_ON(mem_cgroup_is_root(memcg)); /* The page allocation failed. Revert */ if (!page) { memcg_uncharge_kmem(memcg, PAGE_SIZE << order); return; } pc = lookup_page_cgroup(page); lock_page_cgroup(pc); pc->mem_cgroup = memcg; SetPageCgroupUsed(pc); unlock_page_cgroup(pc); } void __memcg_kmem_uncharge_pages(struct page *page, int order) { struct mem_cgroup *memcg = NULL; struct page_cgroup *pc; pc = lookup_page_cgroup(page); /* * Fast unlocked return. Theoretically might have changed, have to * check again after locking. */ if (!PageCgroupUsed(pc)) return; lock_page_cgroup(pc); if (PageCgroupUsed(pc)) { memcg = pc->mem_cgroup; ClearPageCgroupUsed(pc); } unlock_page_cgroup(pc); /* * We trust that only if there is a memcg associated with the page, it * is a valid allocation */ if (!memcg) return; VM_BUG_ON(mem_cgroup_is_root(memcg)); memcg_uncharge_kmem(memcg, PAGE_SIZE << order); } #else static inline void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg) { } #endif /* CONFIG_MEMCG_KMEM */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION) /* * Because tail pages are not marked as "used", set it. We're under * zone->lru_lock, 'splitting on pmd' and compound_lock. * charge/uncharge will be never happen and move_account() is done under * compound_lock(), so we don't have to take care of races. */ void mem_cgroup_split_huge_fixup(struct page *head) { struct page_cgroup *head_pc = lookup_page_cgroup(head); struct page_cgroup *pc; struct mem_cgroup *memcg; int i; if (mem_cgroup_disabled()) return; memcg = head_pc->mem_cgroup; for (i = 1; i < HPAGE_PMD_NR; i++) { pc = head_pc + i; pc->mem_cgroup = memcg; smp_wmb();/* see __commit_charge() */ pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT; } __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], HPAGE_PMD_NR); } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ static inline void mem_cgroup_move_account_page_stat(struct mem_cgroup *from, struct mem_cgroup *to, unsigned int nr_pages, enum mem_cgroup_stat_index idx) { /* Update stat data for mem_cgroup */ preempt_disable(); WARN_ON_ONCE(from->stat->count[idx] < nr_pages); __this_cpu_add(from->stat->count[idx], -nr_pages); __this_cpu_add(to->stat->count[idx], nr_pages); preempt_enable(); } /** * mem_cgroup_move_account - move account of the page * @page: the page * @nr_pages: number of regular pages (>1 for huge pages) * @pc: page_cgroup of the page. * @from: mem_cgroup which the page is moved from. * @to: mem_cgroup which the page is moved to. @from != @to. * * The caller must confirm following. * - page is not on LRU (isolate_page() is useful.) * - compound_lock is held when nr_pages > 1 * * This function doesn't do "charge" to new cgroup and doesn't do "uncharge" * from old cgroup. */ static int mem_cgroup_move_account(struct page *page, unsigned int nr_pages, struct page_cgroup *pc, struct mem_cgroup *from, struct mem_cgroup *to) { unsigned long flags; int ret; bool anon = PageAnon(page); VM_BUG_ON(from == to); VM_BUG_ON(PageLRU(page)); /* * The page is isolated from LRU. So, collapse function * will not handle this page. But page splitting can happen. * Do this check under compound_page_lock(). The caller should * hold it. */ ret = -EBUSY; if (nr_pages > 1 && !PageTransHuge(page)) goto out; lock_page_cgroup(pc); ret = -EINVAL; if (!PageCgroupUsed(pc) || pc->mem_cgroup != from) goto unlock; move_lock_mem_cgroup(from, &flags); if (!anon && page_mapped(page)) mem_cgroup_move_account_page_stat(from, to, nr_pages, MEM_CGROUP_STAT_FILE_MAPPED); if (PageWriteback(page)) mem_cgroup_move_account_page_stat(from, to, nr_pages, MEM_CGROUP_STAT_WRITEBACK); mem_cgroup_charge_statistics(from, page, anon, -nr_pages); /* caller should have done css_get */ pc->mem_cgroup = to; mem_cgroup_charge_statistics(to, page, anon, nr_pages); move_unlock_mem_cgroup(from, &flags); ret = 0; unlock: unlock_page_cgroup(pc); /* * check events */ memcg_check_events(to, page); memcg_check_events(from, page); out: return ret; } /** * mem_cgroup_move_parent - moves page to the parent group * @page: the page to move * @pc: page_cgroup of the page * @child: page's cgroup * * move charges to its parent or the root cgroup if the group has no * parent (aka use_hierarchy==0). * Although this might fail (get_page_unless_zero, isolate_lru_page or * mem_cgroup_move_account fails) the failure is always temporary and * it signals a race with a page removal/uncharge or migration. In the * first case the page is on the way out and it will vanish from the LRU * on the next attempt and the call should be retried later. * Isolation from the LRU fails only if page has been isolated from * the LRU since we looked at it and that usually means either global * reclaim or migration going on. The page will either get back to the * LRU or vanish. * Finaly mem_cgroup_move_account fails only if the page got uncharged * (!PageCgroupUsed) or moved to a different group. The page will * disappear in the next attempt. */ static int mem_cgroup_move_parent(struct page *page, struct page_cgroup *pc, struct mem_cgroup *child) { struct mem_cgroup *parent; unsigned int nr_pages; unsigned long uninitialized_var(flags); int ret; VM_BUG_ON(mem_cgroup_is_root(child)); ret = -EBUSY; if (!get_page_unless_zero(page)) goto out; if (isolate_lru_page(page)) goto put; nr_pages = hpage_nr_pages(page); parent = parent_mem_cgroup(child); /* * If no parent, move charges to root cgroup. */ if (!parent) parent = root_mem_cgroup; if (nr_pages > 1) { VM_BUG_ON(!PageTransHuge(page)); flags = compound_lock_irqsave(page); } ret = mem_cgroup_move_account(page, nr_pages, pc, child, parent); if (!ret) __mem_cgroup_cancel_local_charge(child, nr_pages); if (nr_pages > 1) compound_unlock_irqrestore(page, flags); putback_lru_page(page); put: put_page(page); out: return ret; } /* * Charge the memory controller for page usage. * Return * 0 if the charge was successful * < 0 if the cgroup is over its limit */ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, enum charge_type ctype) { struct mem_cgroup *memcg = NULL; unsigned int nr_pages = 1; bool oom = true; int ret; if (PageTransHuge(page)) { nr_pages <<= compound_order(page); VM_BUG_ON(!PageTransHuge(page)); /* * Never OOM-kill a process for a huge page. The * fault handler will fall back to regular pages. */ oom = false; } ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom); if (ret == -ENOMEM) return ret; __mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false); return 0; } int mem_cgroup_newpage_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { if (mem_cgroup_disabled()) return 0; VM_BUG_ON(page_mapped(page)); VM_BUG_ON(page->mapping && !PageAnon(page)); VM_BUG_ON(!mm); return mem_cgroup_charge_common(page, mm, gfp_mask, MEM_CGROUP_CHARGE_TYPE_ANON); } /* * While swap-in, try_charge -> commit or cancel, the page is locked. * And when try_charge() successfully returns, one refcnt to memcg without * struct page_cgroup is acquired. This refcnt will be consumed by * "commit()" or removed by "cancel()" */ static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page, gfp_t mask, struct mem_cgroup **memcgp) { struct mem_cgroup *memcg; struct page_cgroup *pc; int ret; pc = lookup_page_cgroup(page); /* * Every swap fault against a single page tries to charge the * page, bail as early as possible. shmem_unuse() encounters * already charged pages, too. The USED bit is protected by * the page lock, which serializes swap cache removal, which * in turn serializes uncharging. */ if (PageCgroupUsed(pc)) return 0; if (!do_swap_account) goto charge_cur_mm; memcg = try_get_mem_cgroup_from_page(page); if (!memcg) goto charge_cur_mm; *memcgp = memcg; ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true); css_put(&memcg->css); if (ret == -EINTR) ret = 0; return ret; charge_cur_mm: ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true); if (ret == -EINTR) ret = 0; return ret; } int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page, gfp_t gfp_mask, struct mem_cgroup **memcgp) { *memcgp = NULL; if (mem_cgroup_disabled()) return 0; /* * A racing thread's fault, or swapoff, may have already * updated the pte, and even removed page from swap cache: in * those cases unuse_pte()'s pte_same() test will fail; but * there's also a KSM case which does need to charge the page. */ if (!PageSwapCache(page)) { int ret; ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, memcgp, true); if (ret == -EINTR) ret = 0; return ret; } return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp); } void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg) { if (mem_cgroup_disabled()) return; if (!memcg) return; __mem_cgroup_cancel_charge(memcg, 1); } static void __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg, enum charge_type ctype) { if (mem_cgroup_disabled()) return; if (!memcg) return; __mem_cgroup_commit_charge(memcg, page, 1, ctype, true); /* * Now swap is on-memory. This means this page may be * counted both as mem and swap....double count. * Fix it by uncharging from memsw. Basically, this SwapCache is stable * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page() * may call delete_from_swap_cache() before reach here. */ if (do_swap_account && PageSwapCache(page)) { swp_entry_t ent = {.val = page_private(page)}; mem_cgroup_uncharge_swap(ent); } } void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg) { __mem_cgroup_commit_charge_swapin(page, memcg, MEM_CGROUP_CHARGE_TYPE_ANON); } int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { struct mem_cgroup *memcg = NULL; enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE; int ret; if (mem_cgroup_disabled()) return 0; if (PageCompound(page)) return 0; if (!PageSwapCache(page)) ret = mem_cgroup_charge_common(page, mm, gfp_mask, type); else { /* page is swapcache/shmem */ ret = __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &memcg); if (!ret) __mem_cgroup_commit_charge_swapin(page, memcg, type); } return ret; } static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages, const enum charge_type ctype) { struct memcg_batch_info *batch = NULL; bool uncharge_memsw = true; /* If swapout, usage of swap doesn't decrease */ if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) uncharge_memsw = false; batch = ¤t->memcg_batch; /* * In usual, we do css_get() when we remember memcg pointer. * But in this case, we keep res->usage until end of a series of * uncharges. Then, it's ok to ignore memcg's refcnt. */ if (!batch->memcg) batch->memcg = memcg; /* * do_batch > 0 when unmapping pages or inode invalidate/truncate. * In those cases, all pages freed continuously can be expected to be in * the same cgroup and we have chance to coalesce uncharges. * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE) * because we want to do uncharge as soon as possible. */ if (!batch->do_batch || test_thread_flag(TIF_MEMDIE)) goto direct_uncharge; if (nr_pages > 1) goto direct_uncharge; /* * In typical case, batch->memcg == mem. This means we can * merge a series of uncharges to an uncharge of res_counter. * If not, we uncharge res_counter ony by one. */ if (batch->memcg != memcg) goto direct_uncharge; /* remember freed charge and uncharge it later */ batch->nr_pages++; if (uncharge_memsw) batch->memsw_nr_pages++; return; direct_uncharge: res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE); if (uncharge_memsw) res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE); if (unlikely(batch->memcg != memcg)) memcg_oom_recover(memcg); } /* * uncharge if !page_mapped(page) */ static struct mem_cgroup * __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype, bool end_migration) { struct mem_cgroup *memcg = NULL; unsigned int nr_pages = 1; struct page_cgroup *pc; bool anon; if (mem_cgroup_disabled()) return NULL; if (PageTransHuge(page)) { nr_pages <<= compound_order(page); VM_BUG_ON(!PageTransHuge(page)); } /* * Check if our page_cgroup is valid */ pc = lookup_page_cgroup(page); if (unlikely(!PageCgroupUsed(pc))) return NULL; lock_page_cgroup(pc); memcg = pc->mem_cgroup; if (!PageCgroupUsed(pc)) goto unlock_out; anon = PageAnon(page); switch (ctype) { case MEM_CGROUP_CHARGE_TYPE_ANON: /* * Generally PageAnon tells if it's the anon statistics to be * updated; but sometimes e.g. mem_cgroup_uncharge_page() is * used before page reached the stage of being marked PageAnon. */ anon = true; /* fallthrough */ case MEM_CGROUP_CHARGE_TYPE_DROP: /* See mem_cgroup_prepare_migration() */ if (page_mapped(page)) goto unlock_out; /* * Pages under migration may not be uncharged. But * end_migration() /must/ be the one uncharging the * unused post-migration page and so it has to call * here with the migration bit still set. See the * res_counter handling below. */ if (!end_migration && PageCgroupMigration(pc)) goto unlock_out; break; case MEM_CGROUP_CHARGE_TYPE_SWAPOUT: if (!PageAnon(page)) { /* Shared memory */ if (page->mapping && !page_is_file_cache(page)) goto unlock_out; } else if (page_mapped(page)) /* Anon */ goto unlock_out; break; default: break; } mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages); ClearPageCgroupUsed(pc); /* * pc->mem_cgroup is not cleared here. It will be accessed when it's * freed from LRU. This is safe because uncharged page is expected not * to be reused (freed soon). Exception is SwapCache, it's handled by * special functions. */ unlock_page_cgroup(pc); /* * even after unlock, we have memcg->res.usage here and this memcg * will never be freed, so it's safe to call css_get(). */ memcg_check_events(memcg, page); if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) { mem_cgroup_swap_statistics(memcg, true); css_get(&memcg->css); } /* * Migration does not charge the res_counter for the * replacement page, so leave it alone when phasing out the * page that is unused after the migration. */ if (!end_migration && !mem_cgroup_is_root(memcg)) mem_cgroup_do_uncharge(memcg, nr_pages, ctype); return memcg; unlock_out: unlock_page_cgroup(pc); return NULL; } void mem_cgroup_uncharge_page(struct page *page) { /* early check. */ if (page_mapped(page)) return; VM_BUG_ON(page->mapping && !PageAnon(page)); /* * If the page is in swap cache, uncharge should be deferred * to the swap path, which also properly accounts swap usage * and handles memcg lifetime. * * Note that this check is not stable and reclaim may add the * page to swap cache at any time after this. However, if the * page is not in swap cache by the time page->mapcount hits * 0, there won't be any page table references to the swap * slot, and reclaim will free it and not actually write the * page to disk. */ if (PageSwapCache(page)) return; __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false); } void mem_cgroup_uncharge_cache_page(struct page *page) { VM_BUG_ON(page_mapped(page)); VM_BUG_ON(page->mapping); __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false); } /* * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate. * In that cases, pages are freed continuously and we can expect pages * are in the same memcg. All these calls itself limits the number of * pages freed at once, then uncharge_start/end() is called properly. * This may be called prural(2) times in a context, */ void mem_cgroup_uncharge_start(void) { current->memcg_batch.do_batch++; /* We can do nest. */ if (current->memcg_batch.do_batch == 1) { current->memcg_batch.memcg = NULL; current->memcg_batch.nr_pages = 0; current->memcg_batch.memsw_nr_pages = 0; } } void mem_cgroup_uncharge_end(void) { struct memcg_batch_info *batch = ¤t->memcg_batch; if (!batch->do_batch) return; batch->do_batch--; if (batch->do_batch) /* If stacked, do nothing. */ return; if (!batch->memcg) return; /* * This "batch->memcg" is valid without any css_get/put etc... * bacause we hide charges behind us. */ if (batch->nr_pages) res_counter_uncharge(&batch->memcg->res, batch->nr_pages * PAGE_SIZE); if (batch->memsw_nr_pages) res_counter_uncharge(&batch->memcg->memsw, batch->memsw_nr_pages * PAGE_SIZE); memcg_oom_recover(batch->memcg); /* forget this pointer (for sanity check) */ batch->memcg = NULL; } #ifdef CONFIG_SWAP /* * called after __delete_from_swap_cache() and drop "page" account. * memcg information is recorded to swap_cgroup of "ent" */ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) { struct mem_cgroup *memcg; int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT; if (!swapout) /* this was a swap cache but the swap is unused ! */ ctype = MEM_CGROUP_CHARGE_TYPE_DROP; memcg = __mem_cgroup_uncharge_common(page, ctype, false); /* * record memcg information, if swapout && memcg != NULL, * css_get() was called in uncharge(). */ if (do_swap_account && swapout && memcg) swap_cgroup_record(ent, mem_cgroup_id(memcg)); } #endif #ifdef CONFIG_MEMCG_SWAP /* * called from swap_entry_free(). remove record in swap_cgroup and * uncharge "memsw" account. */ void mem_cgroup_uncharge_swap(swp_entry_t ent) { struct mem_cgroup *memcg; unsigned short id; if (!do_swap_account) return; id = swap_cgroup_record(ent, 0); rcu_read_lock(); memcg = mem_cgroup_lookup(id); if (memcg) { /* * We uncharge this because swap is freed. * This memcg can be obsolete one. We avoid calling css_tryget */ if (!mem_cgroup_is_root(memcg)) res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_swap_statistics(memcg, false); css_put(&memcg->css); } rcu_read_unlock(); } /** * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. * @entry: swap entry to be moved * @from: mem_cgroup which the entry is moved from * @to: mem_cgroup which the entry is moved to * * It succeeds only when the swap_cgroup's record for this entry is the same * as the mem_cgroup's id of @from. * * Returns 0 on success, -EINVAL on failure. * * The caller must have charged to @to, IOW, called res_counter_charge() about * both res and memsw, and called css_get(). */ static int mem_cgroup_move_swap_account(swp_entry_t entry, struct mem_cgroup *from, struct mem_cgroup *to) { unsigned short old_id, new_id; old_id = mem_cgroup_id(from); new_id = mem_cgroup_id(to); if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { mem_cgroup_swap_statistics(from, false); mem_cgroup_swap_statistics(to, true); /* * This function is only called from task migration context now. * It postpones res_counter and refcount handling till the end * of task migration(mem_cgroup_clear_mc()) for performance * improvement. But we cannot postpone css_get(to) because if * the process that has been moved to @to does swap-in, the * refcount of @to might be decreased to 0. * * We are in attach() phase, so the cgroup is guaranteed to be * alive, so we can just call css_get(). */ css_get(&to->css); return 0; } return -EINVAL; } #else static inline int mem_cgroup_move_swap_account(swp_entry_t entry, struct mem_cgroup *from, struct mem_cgroup *to) { return -EINVAL; } #endif /* * Before starting migration, account PAGE_SIZE to mem_cgroup that the old * page belongs to. */ void mem_cgroup_prepare_migration(struct page *page, struct page *newpage, struct mem_cgroup **memcgp) { struct mem_cgroup *memcg = NULL; unsigned int nr_pages = 1; struct page_cgroup *pc; enum charge_type ctype; *memcgp = NULL; if (mem_cgroup_disabled()) return; if (PageTransHuge(page)) nr_pages <<= compound_order(page); pc = lookup_page_cgroup(page); lock_page_cgroup(pc); if (PageCgroupUsed(pc)) { memcg = pc->mem_cgroup; css_get(&memcg->css); /* * At migrating an anonymous page, its mapcount goes down * to 0 and uncharge() will be called. But, even if it's fully * unmapped, migration may fail and this page has to be * charged again. We set MIGRATION flag here and delay uncharge * until end_migration() is called * * Corner Case Thinking * A) * When the old page was mapped as Anon and it's unmap-and-freed * while migration was ongoing. * If unmap finds the old page, uncharge() of it will be delayed * until end_migration(). If unmap finds a new page, it's * uncharged when it make mapcount to be 1->0. If unmap code * finds swap_migration_entry, the new page will not be mapped * and end_migration() will find it(mapcount==0). * * B) * When the old page was mapped but migraion fails, the kernel * remaps it. A charge for it is kept by MIGRATION flag even * if mapcount goes down to 0. We can do remap successfully * without charging it again. * * C) * The "old" page is under lock_page() until the end of * migration, so, the old page itself will not be swapped-out. * If the new page is swapped out before end_migraton, our * hook to usual swap-out path will catch the event. */ if (PageAnon(page)) SetPageCgroupMigration(pc); } unlock_page_cgroup(pc); /* * If the page is not charged at this point, * we return here. */ if (!memcg) return; *memcgp = memcg; /* * We charge new page before it's used/mapped. So, even if unlock_page() * is called before end_migration, we can catch all events on this new * page. In the case new page is migrated but not remapped, new page's * mapcount will be finally 0 and we call uncharge in end_migration(). */ if (PageAnon(page)) ctype = MEM_CGROUP_CHARGE_TYPE_ANON; else ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; /* * The page is committed to the memcg, but it's not actually * charged to the res_counter since we plan on replacing the * old one and only one page is going to be left afterwards. */ __mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false); } /* remove redundant charge if migration failed*/ void mem_cgroup_end_migration(struct mem_cgroup *memcg, struct page *oldpage, struct page *newpage, bool migration_ok) { struct page *used, *unused; struct page_cgroup *pc; bool anon; if (!memcg) return; if (!migration_ok) { used = oldpage; unused = newpage; } else { used = newpage; unused = oldpage; } anon = PageAnon(used); __mem_cgroup_uncharge_common(unused, anon ? MEM_CGROUP_CHARGE_TYPE_ANON : MEM_CGROUP_CHARGE_TYPE_CACHE, true); css_put(&memcg->css); /* * We disallowed uncharge of pages under migration because mapcount * of the page goes down to zero, temporarly. * Clear the flag and check the page should be charged. */ pc = lookup_page_cgroup(oldpage); lock_page_cgroup(pc); ClearPageCgroupMigration(pc); unlock_page_cgroup(pc); /* * If a page is a file cache, radix-tree replacement is very atomic * and we can skip this check. When it was an Anon page, its mapcount * goes down to 0. But because we added MIGRATION flage, it's not * uncharged yet. There are several case but page->mapcount check * and USED bit check in mem_cgroup_uncharge_page() will do enough * check. (see prepare_charge() also) */ if (anon) mem_cgroup_uncharge_page(used); } /* * At replace page cache, newpage is not under any memcg but it's on * LRU. So, this function doesn't touch res_counter but handles LRU * in correct way. Both pages are locked so we cannot race with uncharge. */ void mem_cgroup_replace_page_cache(struct page *oldpage, struct page *newpage) { struct mem_cgroup *memcg = NULL; struct page_cgroup *pc; enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE; if (mem_cgroup_disabled()) return; pc = lookup_page_cgroup(oldpage); /* fix accounting on old pages */ lock_page_cgroup(pc); if (PageCgroupUsed(pc)) { memcg = pc->mem_cgroup; mem_cgroup_charge_statistics(memcg, oldpage, false, -1); ClearPageCgroupUsed(pc); } unlock_page_cgroup(pc); /* * When called from shmem_replace_page(), in some cases the * oldpage has already been charged, and in some cases not. */ if (!memcg) return; /* * Even if newpage->mapping was NULL before starting replacement, * the newpage may be on LRU(or pagevec for LRU) already. We lock * LRU while we overwrite pc->mem_cgroup. */ __mem_cgroup_commit_charge(memcg, newpage, 1, type, true); } #ifdef CONFIG_DEBUG_VM static struct page_cgroup *lookup_page_cgroup_used(struct page *page) { struct page_cgroup *pc; pc = lookup_page_cgroup(page); /* * Can be NULL while feeding pages into the page allocator for * the first time, i.e. during boot or memory hotplug; * or when mem_cgroup_disabled(). */ if (likely(pc) && PageCgroupUsed(pc)) return pc; return NULL; } bool mem_cgroup_bad_page_check(struct page *page) { if (mem_cgroup_disabled()) return false; return lookup_page_cgroup_used(page) != NULL; } void mem_cgroup_print_bad_page(struct page *page) { struct page_cgroup *pc; pc = lookup_page_cgroup_used(page); if (pc) { pr_alert("pc:%p pc->flags:%lx pc->mem_cgroup:%p\n", pc, pc->flags, pc->mem_cgroup); } } #endif static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, unsigned long long val) { int retry_count; u64 memswlimit, memlimit; int ret = 0; int children = mem_cgroup_count_children(memcg); u64 curusage, oldusage; int enlarge; /* * For keeping hierarchical_reclaim simple, how long we should retry * is depends on callers. We set our retry-count to be function * of # of children which we should visit in this loop. */ retry_count = MEM_CGROUP_RECLAIM_RETRIES * children; oldusage = res_counter_read_u64(&memcg->res, RES_USAGE); enlarge = 0; while (retry_count) { if (signal_pending(current)) { ret = -EINTR; break; } /* * Rather than hide all in some function, I do this in * open coded manner. You see what this really does. * We have to guarantee memcg->res.limit <= memcg->memsw.limit. */ mutex_lock(&set_limit_mutex); memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); if (memswlimit < val) { ret = -EINVAL; mutex_unlock(&set_limit_mutex); break; } memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT); if (memlimit < val) enlarge = 1; ret = res_counter_set_limit(&memcg->res, val); if (!ret) { if (memswlimit == val) memcg->memsw_is_minimum = true; else memcg->memsw_is_minimum = false; } mutex_unlock(&set_limit_mutex); if (!ret) break; mem_cgroup_reclaim(memcg, GFP_KERNEL, MEM_CGROUP_RECLAIM_SHRINK); curusage = res_counter_read_u64(&memcg->res, RES_USAGE); /* Usage is reduced ? */ if (curusage >= oldusage) retry_count--; else oldusage = curusage; } if (!ret && enlarge) memcg_oom_recover(memcg); return ret; } static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, unsigned long long val) { int retry_count; u64 memlimit, memswlimit, oldusage, curusage; int children = mem_cgroup_count_children(memcg); int ret = -EBUSY; int enlarge = 0; /* see mem_cgroup_resize_res_limit */ retry_count = children * MEM_CGROUP_RECLAIM_RETRIES; oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); while (retry_count) { if (signal_pending(current)) { ret = -EINTR; break; } /* * Rather than hide all in some function, I do this in * open coded manner. You see what this really does. * We have to guarantee memcg->res.limit <= memcg->memsw.limit. */ mutex_lock(&set_limit_mutex); memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT); if (memlimit > val) { ret = -EINVAL; mutex_unlock(&set_limit_mutex); break; } memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); if (memswlimit < val) enlarge = 1; ret = res_counter_set_limit(&memcg->memsw, val); if (!ret) { if (memlimit == val) memcg->memsw_is_minimum = true; else memcg->memsw_is_minimum = false; } mutex_unlock(&set_limit_mutex); if (!ret) break; mem_cgroup_reclaim(memcg, GFP_KERNEL, MEM_CGROUP_RECLAIM_NOSWAP | MEM_CGROUP_RECLAIM_SHRINK); curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE); /* Usage is reduced ? */ if (curusage >= oldusage) retry_count--; else oldusage = curusage; } if (!ret && enlarge) memcg_oom_recover(memcg); return ret; } /** * mem_cgroup_force_empty_list - clears LRU of a group * @memcg: group to clear * @node: NUMA node * @zid: zone id * @lru: lru to to clear * * Traverse a specified page_cgroup list and try to drop them all. This doesn't * reclaim the pages page themselves - pages are moved to the parent (or root) * group. */ static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg, int node, int zid, enum lru_list lru) { struct lruvec *lruvec; unsigned long flags; struct list_head *list; struct page *busy; struct zone *zone; zone = &NODE_DATA(node)->node_zones[zid]; lruvec = mem_cgroup_zone_lruvec(zone, memcg); list = &lruvec->lists[lru]; busy = NULL; do { struct page_cgroup *pc; struct page *page; spin_lock_irqsave(&zone->lru_lock, flags); if (list_empty(list)) { spin_unlock_irqrestore(&zone->lru_lock, flags); break; } page = list_entry(list->prev, struct page, lru); if (busy == page) { list_move(&page->lru, list); busy = NULL; spin_unlock_irqrestore(&zone->lru_lock, flags); continue; } spin_unlock_irqrestore(&zone->lru_lock, flags); pc = lookup_page_cgroup(page); if (mem_cgroup_move_parent(page, pc, memcg)) { /* found lock contention or "pc" is obsolete. */ busy = page; cond_resched(); } else busy = NULL; } while (!list_empty(list)); } /* * make mem_cgroup's charge to be 0 if there is no task by moving * all the charges and pages to the parent. * This enables deleting this mem_cgroup. * * Caller is responsible for holding css reference on the memcg. */ static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg) { int node, zid; u64 usage; do { /* This is for making all *used* pages to be on LRU. */ lru_add_drain_all(); drain_all_stock_sync(memcg); mem_cgroup_start_move(memcg); for_each_node_state(node, N_MEMORY) { for (zid = 0; zid < MAX_NR_ZONES; zid++) { enum lru_list lru; for_each_lru(lru) { mem_cgroup_force_empty_list(memcg, node, zid, lru); } } } mem_cgroup_end_move(memcg); memcg_oom_recover(memcg); cond_resched(); /* * Kernel memory may not necessarily be trackable to a specific * process. So they are not migrated, and therefore we can't * expect their value to drop to 0 here. * Having res filled up with kmem only is enough. * * This is a safety check because mem_cgroup_force_empty_list * could have raced with mem_cgroup_replace_page_cache callers * so the lru seemed empty but the page could have been added * right after the check. RES_USAGE should be safe as we always * charge before adding to the LRU. */ usage = res_counter_read_u64(&memcg->res, RES_USAGE) - res_counter_read_u64(&memcg->kmem, RES_USAGE); } while (usage > 0); } /* * This mainly exists for tests during the setting of set of use_hierarchy. * Since this is the very setting we are changing, the current hierarchy value * is meaningless */ static inline bool __memcg_has_children(struct mem_cgroup *memcg) { struct cgroup_subsys_state *pos; /* bounce at first found */ css_for_each_child(pos, &memcg->css) return true; return false; } /* * Must be called with memcg_create_mutex held, unless the cgroup is guaranteed * to be already dead (as in mem_cgroup_force_empty, for instance). This is * from mem_cgroup_count_children(), in the sense that we don't really care how * many children we have; we only need to know if we have any. It also counts * any memcg without hierarchy as infertile. */ static inline bool memcg_has_children(struct mem_cgroup *memcg) { return memcg->use_hierarchy && __memcg_has_children(memcg); } /* * Reclaims as many pages from the given memcg as possible and moves * the rest to the parent. * * Caller is responsible for holding css reference for memcg. */ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) { int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; struct cgroup *cgrp = memcg->css.cgroup; /* returns EBUSY if there is a task or if we come here twice. */ if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children)) return -EBUSY; /* we call try-to-free pages for make this cgroup empty */ lru_add_drain_all(); /* try to free all pages in this cgroup */ while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) { int progress; if (signal_pending(current)) return -EINTR; progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, false); if (!progress) { nr_retries--; /* maybe some writeback is necessary */ congestion_wait(BLK_RW_ASYNC, HZ/10); } } lru_add_drain(); mem_cgroup_reparent_charges(memcg); return 0; } static int mem_cgroup_force_empty_write(struct cgroup_subsys_state *css, unsigned int event) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); if (mem_cgroup_is_root(memcg)) return -EINVAL; return mem_cgroup_force_empty(memcg); } static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css, struct cftype *cft) { return mem_cgroup_from_css(css)->use_hierarchy; } static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { int retval = 0; struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent_memcg = mem_cgroup_from_css(css_parent(&memcg->css)); mutex_lock(&memcg_create_mutex); if (memcg->use_hierarchy == val) goto out; /* * If parent's use_hierarchy is set, we can't make any modifications * in the child subtrees. If it is unset, then the change can * occur, provided the current cgroup has no children. * * For the root cgroup, parent_mem is NULL, we allow value to be * set if there are no children. */ if ((!parent_memcg || !parent_memcg->use_hierarchy) && (val == 1 || val == 0)) { if (!__memcg_has_children(memcg)) memcg->use_hierarchy = val; else retval = -EBUSY; } else retval = -EINVAL; out: mutex_unlock(&memcg_create_mutex); return retval; } static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg, enum mem_cgroup_stat_index idx) { struct mem_cgroup *iter; long val = 0; /* Per-cpu values can be negative, use a signed accumulator */ for_each_mem_cgroup_tree(iter, memcg) val += mem_cgroup_read_stat(iter, idx); if (val < 0) /* race ? */ val = 0; return val; } static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) { u64 val; if (!mem_cgroup_is_root(memcg)) { if (!swap) return res_counter_read_u64(&memcg->res, RES_USAGE); else return res_counter_read_u64(&memcg->memsw, RES_USAGE); } /* * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS * as well as in MEM_CGROUP_STAT_RSS_HUGE. */ val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS); if (swap) val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP); return val << PAGE_SHIFT; } static ssize_t mem_cgroup_read(struct cgroup_subsys_state *css, struct cftype *cft, struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); char str[64]; u64 val; int name, len; enum res_type type; type = MEMFILE_TYPE(cft->private); name = MEMFILE_ATTR(cft->private); switch (type) { case _MEM: if (name == RES_USAGE) val = mem_cgroup_usage(memcg, false); else val = res_counter_read_u64(&memcg->res, name); break; case _MEMSWAP: if (name == RES_USAGE) val = mem_cgroup_usage(memcg, true); else val = res_counter_read_u64(&memcg->memsw, name); break; case _KMEM: val = res_counter_read_u64(&memcg->kmem, name); break; default: BUG(); } len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val); return simple_read_from_buffer(buf, nbytes, ppos, str, len); } static int memcg_update_kmem_limit(struct cgroup_subsys_state *css, u64 val) { int ret = -EINVAL; #ifdef CONFIG_MEMCG_KMEM struct mem_cgroup *memcg = mem_cgroup_from_css(css); /* * For simplicity, we won't allow this to be disabled. It also can't * be changed if the cgroup has children already, or if tasks had * already joined. * * If tasks join before we set the limit, a person looking at * kmem.usage_in_bytes will have no way to determine when it took * place, which makes the value quite meaningless. * * After it first became limited, changes in the value of the limit are * of course permitted. */ mutex_lock(&memcg_create_mutex); mutex_lock(&set_limit_mutex); if (!memcg->kmem_account_flags && val != RES_COUNTER_MAX) { if (cgroup_task_count(css->cgroup) || memcg_has_children(memcg)) { ret = -EBUSY; goto out; } ret = res_counter_set_limit(&memcg->kmem, val); VM_BUG_ON(ret); ret = memcg_update_cache_sizes(memcg); if (ret) { res_counter_set_limit(&memcg->kmem, RES_COUNTER_MAX); goto out; } static_key_slow_inc(&memcg_kmem_enabled_key); /* * setting the active bit after the inc will guarantee no one * starts accounting before all call sites are patched */ memcg_kmem_set_active(memcg); } else ret = res_counter_set_limit(&memcg->kmem, val); out: mutex_unlock(&set_limit_mutex); mutex_unlock(&memcg_create_mutex); #endif return ret; } #ifdef CONFIG_MEMCG_KMEM static int memcg_propagate_kmem(struct mem_cgroup *memcg) { int ret = 0; struct mem_cgroup *parent = parent_mem_cgroup(memcg); if (!parent) goto out; memcg->kmem_account_flags = parent->kmem_account_flags; /* * When that happen, we need to disable the static branch only on those * memcgs that enabled it. To achieve this, we would be forced to * complicate the code by keeping track of which memcgs were the ones * that actually enabled limits, and which ones got it from its * parents. * * It is a lot simpler just to do static_key_slow_inc() on every child * that is accounted. */ if (!memcg_kmem_is_active(memcg)) goto out; /* * __mem_cgroup_free() will issue static_key_slow_dec() because this * memcg is active already. If the later initialization fails then the * cgroup core triggers the cleanup so we do not have to do it here. */ static_key_slow_inc(&memcg_kmem_enabled_key); mutex_lock(&set_limit_mutex); memcg_stop_kmem_account(); ret = memcg_update_cache_sizes(memcg); memcg_resume_kmem_account(); mutex_unlock(&set_limit_mutex); out: return ret; } #endif /* CONFIG_MEMCG_KMEM */ /* * The user of this function is... * RES_LIMIT. */ static int mem_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft, const char *buffer) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); enum res_type type; int name; unsigned long long val; int ret; type = MEMFILE_TYPE(cft->private); name = MEMFILE_ATTR(cft->private); switch (name) { case RES_LIMIT: if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */ ret = -EINVAL; break; } /* This function does all necessary parse...reuse it */ ret = res_counter_memparse_write_strategy(buffer, &val); if (ret) break; if (type == _MEM) ret = mem_cgroup_resize_limit(memcg, val); else if (type == _MEMSWAP) ret = mem_cgroup_resize_memsw_limit(memcg, val); else if (type == _KMEM) ret = memcg_update_kmem_limit(css, val); else return -EINVAL; break; case RES_SOFT_LIMIT: ret = res_counter_memparse_write_strategy(buffer, &val); if (ret) break; /* * For memsw, soft limits are hard to implement in terms * of semantics, for now, we support soft limits for * control without swap */ if (type == _MEM) ret = res_counter_set_soft_limit(&memcg->res, val); else ret = -EINVAL; break; default: ret = -EINVAL; /* should be BUG() ? */ break; } return ret; } static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg, unsigned long long *mem_limit, unsigned long long *memsw_limit) { unsigned long long min_limit, min_memsw_limit, tmp; min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT); min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT); if (!memcg->use_hierarchy) goto out; while (css_parent(&memcg->css)) { memcg = mem_cgroup_from_css(css_parent(&memcg->css)); if (!memcg->use_hierarchy) break; tmp = res_counter_read_u64(&memcg->res, RES_LIMIT); min_limit = min(min_limit, tmp); tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT); min_memsw_limit = min(min_memsw_limit, tmp); } out: *mem_limit = min_limit; *memsw_limit = min_memsw_limit; } static int mem_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); int name; enum res_type type; type = MEMFILE_TYPE(event); name = MEMFILE_ATTR(event); switch (name) { case RES_MAX_USAGE: if (type == _MEM) res_counter_reset_max(&memcg->res); else if (type == _MEMSWAP) res_counter_reset_max(&memcg->memsw); else if (type == _KMEM) res_counter_reset_max(&memcg->kmem); else return -EINVAL; break; case RES_FAILCNT: if (type == _MEM) res_counter_reset_failcnt(&memcg->res); else if (type == _MEMSWAP) res_counter_reset_failcnt(&memcg->memsw); else if (type == _KMEM) res_counter_reset_failcnt(&memcg->kmem); else return -EINVAL; break; } return 0; } static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, struct cftype *cft) { return mem_cgroup_from_css(css)->move_charge_at_immigrate; } #ifdef CONFIG_MMU static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); if (val >= (1 << NR_MOVE_TYPE)) return -EINVAL; /* * No kind of locking is needed in here, because ->can_attach() will * check this value once in the beginning of the process, and then carry * on with stale data. This means that changes to this value will only * affect task migrations starting after the change. */ memcg->move_charge_at_immigrate = val; return 0; } #else static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { return -ENOSYS; } #endif #ifdef CONFIG_NUMA static int memcg_numa_stat_show(struct cgroup_subsys_state *css, struct cftype *cft, struct seq_file *m) { int nid; unsigned long total_nr, file_nr, anon_nr, unevictable_nr; unsigned long node_nr; struct mem_cgroup *memcg = mem_cgroup_from_css(css); total_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL); seq_printf(m, "total=%lu", total_nr); for_each_node_state(nid, N_MEMORY) { node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL); seq_printf(m, " N%d=%lu", nid, node_nr); } seq_putc(m, '\n'); file_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_FILE); seq_printf(m, "file=%lu", file_nr); for_each_node_state(nid, N_MEMORY) { node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE); seq_printf(m, " N%d=%lu", nid, node_nr); } seq_putc(m, '\n'); anon_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_ANON); seq_printf(m, "anon=%lu", anon_nr); for_each_node_state(nid, N_MEMORY) { node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON); seq_printf(m, " N%d=%lu", nid, node_nr); } seq_putc(m, '\n'); unevictable_nr = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_UNEVICTABLE)); seq_printf(m, "unevictable=%lu", unevictable_nr); for_each_node_state(nid, N_MEMORY) { node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, BIT(LRU_UNEVICTABLE)); seq_printf(m, " N%d=%lu", nid, node_nr); } seq_putc(m, '\n'); return 0; } #endif /* CONFIG_NUMA */ static inline void mem_cgroup_lru_names_not_uptodate(void) { BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS); } static int memcg_stat_show(struct cgroup_subsys_state *css, struct cftype *cft, struct seq_file *m) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *mi; unsigned int i; for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) continue; seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i], mem_cgroup_read_stat(memcg, i) * PAGE_SIZE); } for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) seq_printf(m, "%s %lu\n", mem_cgroup_events_names[i], mem_cgroup_read_events(memcg, i)); for (i = 0; i < NR_LRU_LISTS; i++) seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i], mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE); /* Hierarchical information */ { unsigned long long limit, memsw_limit; memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit); seq_printf(m, "hierarchical_memory_limit %llu\n", limit); if (do_swap_account) seq_printf(m, "hierarchical_memsw_limit %llu\n", memsw_limit); } for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) { long long val = 0; if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account) continue; for_each_mem_cgroup_tree(mi, memcg) val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE; seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val); } for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) { unsigned long long val = 0; for_each_mem_cgroup_tree(mi, memcg) val += mem_cgroup_read_events(mi, i); seq_printf(m, "total_%s %llu\n", mem_cgroup_events_names[i], val); } for (i = 0; i < NR_LRU_LISTS; i++) { unsigned long long val = 0; for_each_mem_cgroup_tree(mi, memcg) val += mem_cgroup_nr_lru_pages(mi, BIT(i)) * PAGE_SIZE; seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], val); } #ifdef CONFIG_DEBUG_VM { int nid, zid; struct mem_cgroup_per_zone *mz; struct zone_reclaim_stat *rstat; unsigned long recent_rotated[2] = {0, 0}; unsigned long recent_scanned[2] = {0, 0}; for_each_online_node(nid) for (zid = 0; zid < MAX_NR_ZONES; zid++) { mz = mem_cgroup_zoneinfo(memcg, nid, zid); rstat = &mz->lruvec.reclaim_stat; recent_rotated[0] += rstat->recent_rotated[0]; recent_rotated[1] += rstat->recent_rotated[1]; recent_scanned[0] += rstat->recent_scanned[0]; recent_scanned[1] += rstat->recent_scanned[1]; } seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]); seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]); seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]); seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]); } #endif return 0; } static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css, struct cftype *cft) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); return mem_cgroup_swappiness(memcg); } static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css)); if (val > 100 || !parent) return -EINVAL; mutex_lock(&memcg_create_mutex); /* If under hierarchy, only empty-root can set this value */ if ((parent->use_hierarchy) || memcg_has_children(memcg)) { mutex_unlock(&memcg_create_mutex); return -EINVAL; } memcg->swappiness = val; mutex_unlock(&memcg_create_mutex); return 0; } static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) { struct mem_cgroup_threshold_ary *t; u64 usage; int i; rcu_read_lock(); if (!swap) t = rcu_dereference(memcg->thresholds.primary); else t = rcu_dereference(memcg->memsw_thresholds.primary); if (!t) goto unlock; usage = mem_cgroup_usage(memcg, swap); /* * current_threshold points to threshold just below or equal to usage. * If it's not true, a threshold was crossed after last * call of __mem_cgroup_threshold(). */ i = t->current_threshold; /* * Iterate backward over array of thresholds starting from * current_threshold and check if a threshold is crossed. * If none of thresholds below usage is crossed, we read * only one element of the array here. */ for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--) eventfd_signal(t->entries[i].eventfd, 1); /* i = current_threshold + 1 */ i++; /* * Iterate forward over array of thresholds starting from * current_threshold+1 and check if a threshold is crossed. * If none of thresholds above usage is crossed, we read * only one element of the array here. */ for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++) eventfd_signal(t->entries[i].eventfd, 1); /* Update current_threshold */ t->current_threshold = i - 1; unlock: rcu_read_unlock(); } static void mem_cgroup_threshold(struct mem_cgroup *memcg) { while (memcg) { __mem_cgroup_threshold(memcg, false); if (do_swap_account) __mem_cgroup_threshold(memcg, true); memcg = parent_mem_cgroup(memcg); } } static int compare_thresholds(const void *a, const void *b) { const struct mem_cgroup_threshold *_a = a; const struct mem_cgroup_threshold *_b = b; if (_a->threshold > _b->threshold) return 1; if (_a->threshold < _b->threshold) return -1; return 0; } static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg) { struct mem_cgroup_eventfd_list *ev; list_for_each_entry(ev, &memcg->oom_notify, list) eventfd_signal(ev->eventfd, 1); return 0; } static void mem_cgroup_oom_notify(struct mem_cgroup *memcg) { struct mem_cgroup *iter; for_each_mem_cgroup_tree(iter, memcg) mem_cgroup_oom_notify_cb(iter); } static int mem_cgroup_usage_register_event(struct cgroup_subsys_state *css, struct cftype *cft, struct eventfd_ctx *eventfd, const char *args) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_thresholds *thresholds; struct mem_cgroup_threshold_ary *new; enum res_type type = MEMFILE_TYPE(cft->private); u64 threshold, usage; int i, size, ret; ret = res_counter_memparse_write_strategy(args, &threshold); if (ret) return ret; mutex_lock(&memcg->thresholds_lock); if (type == _MEM) thresholds = &memcg->thresholds; else if (type == _MEMSWAP) thresholds = &memcg->memsw_thresholds; else BUG(); usage = mem_cgroup_usage(memcg, type == _MEMSWAP); /* Check if a threshold crossed before adding a new one */ if (thresholds->primary) __mem_cgroup_threshold(memcg, type == _MEMSWAP); size = thresholds->primary ? thresholds->primary->size + 1 : 1; /* Allocate memory for new array of thresholds */ new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold), GFP_KERNEL); if (!new) { ret = -ENOMEM; goto unlock; } new->size = size; /* Copy thresholds (if any) to new array */ if (thresholds->primary) { memcpy(new->entries, thresholds->primary->entries, (size - 1) * sizeof(struct mem_cgroup_threshold)); } /* Add new threshold */ new->entries[size - 1].eventfd = eventfd; new->entries[size - 1].threshold = threshold; /* Sort thresholds. Registering of new threshold isn't time-critical */ sort(new->entries, size, sizeof(struct mem_cgroup_threshold), compare_thresholds, NULL); /* Find current threshold */ new->current_threshold = -1; for (i = 0; i < size; i++) { if (new->entries[i].threshold <= usage) { /* * new->current_threshold will not be used until * rcu_assign_pointer(), so it's safe to increment * it here. */ ++new->current_threshold; } else break; } /* Free old spare buffer and save old primary buffer as spare */ kfree(thresholds->spare); thresholds->spare = thresholds->primary; rcu_assign_pointer(thresholds->primary, new); /* To be sure that nobody uses thresholds */ synchronize_rcu(); unlock: mutex_unlock(&memcg->thresholds_lock); return ret; } static void mem_cgroup_usage_unregister_event(struct cgroup_subsys_state *css, struct cftype *cft, struct eventfd_ctx *eventfd) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_thresholds *thresholds; struct mem_cgroup_threshold_ary *new; enum res_type type = MEMFILE_TYPE(cft->private); u64 usage; int i, j, size; mutex_lock(&memcg->thresholds_lock); if (type == _MEM) thresholds = &memcg->thresholds; else if (type == _MEMSWAP) thresholds = &memcg->memsw_thresholds; else BUG(); if (!thresholds->primary) goto unlock; usage = mem_cgroup_usage(memcg, type == _MEMSWAP); /* Check if a threshold crossed before removing */ __mem_cgroup_threshold(memcg, type == _MEMSWAP); /* Calculate new number of threshold */ size = 0; for (i = 0; i < thresholds->primary->size; i++) { if (thresholds->primary->entries[i].eventfd != eventfd) size++; } new = thresholds->spare; /* Set thresholds array to NULL if we don't have thresholds */ if (!size) { kfree(new); new = NULL; goto swap_buffers; } new->size = size; /* Copy thresholds and find current threshold */ new->current_threshold = -1; for (i = 0, j = 0; i < thresholds->primary->size; i++) { if (thresholds->primary->entries[i].eventfd == eventfd) continue; new->entries[j] = thresholds->primary->entries[i]; if (new->entries[j].threshold <= usage) { /* * new->current_threshold will not be used * until rcu_assign_pointer(), so it's safe to increment * it here. */ ++new->current_threshold; } j++; } swap_buffers: /* Swap primary and spare array */ thresholds->spare = thresholds->primary; /* If all events are unregistered, free the spare array */ if (!new) { kfree(thresholds->spare); thresholds->spare = NULL; } rcu_assign_pointer(thresholds->primary, new); /* To be sure that nobody uses thresholds */ synchronize_rcu(); unlock: mutex_unlock(&memcg->thresholds_lock); } static int mem_cgroup_oom_register_event(struct cgroup_subsys_state *css, struct cftype *cft, struct eventfd_ctx *eventfd, const char *args) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_eventfd_list *event; enum res_type type = MEMFILE_TYPE(cft->private); BUG_ON(type != _OOM_TYPE); event = kmalloc(sizeof(*event), GFP_KERNEL); if (!event) return -ENOMEM; spin_lock(&memcg_oom_lock); event->eventfd = eventfd; list_add(&event->list, &memcg->oom_notify); /* already in OOM ? */ if (atomic_read(&memcg->under_oom)) eventfd_signal(eventfd, 1); spin_unlock(&memcg_oom_lock); return 0; } static void mem_cgroup_oom_unregister_event(struct cgroup_subsys_state *css, struct cftype *cft, struct eventfd_ctx *eventfd) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_eventfd_list *ev, *tmp; enum res_type type = MEMFILE_TYPE(cft->private); BUG_ON(type != _OOM_TYPE); spin_lock(&memcg_oom_lock); list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) { if (ev->eventfd == eventfd) { list_del(&ev->list); kfree(ev); } } spin_unlock(&memcg_oom_lock); } static int mem_cgroup_oom_control_read(struct cgroup_subsys_state *css, struct cftype *cft, struct cgroup_map_cb *cb) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable); if (atomic_read(&memcg->under_oom)) cb->fill(cb, "under_oom", 1); else cb->fill(cb, "under_oom", 0); return 0; } static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(&memcg->css)); /* cannot set to root cgroup and only 0 and 1 are allowed */ if (!parent || !((val == 0) || (val == 1))) return -EINVAL; mutex_lock(&memcg_create_mutex); /* oom-kill-disable is a flag for subhierarchy. */ if ((parent->use_hierarchy) || memcg_has_children(memcg)) { mutex_unlock(&memcg_create_mutex); return -EINVAL; } memcg->oom_kill_disable = val; if (!val) memcg_oom_recover(memcg); mutex_unlock(&memcg_create_mutex); return 0; } #ifdef CONFIG_MEMCG_KMEM static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) { int ret; memcg->kmemcg_id = -1; ret = memcg_propagate_kmem(memcg); if (ret) return ret; return mem_cgroup_sockets_init(memcg, ss); } static void memcg_destroy_kmem(struct mem_cgroup *memcg) { mem_cgroup_sockets_destroy(memcg); } static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) { if (!memcg_kmem_is_active(memcg)) return; /* * kmem charges can outlive the cgroup. In the case of slab * pages, for instance, a page contain objects from various * processes. As we prevent from taking a reference for every * such allocation we have to be careful when doing uncharge * (see memcg_uncharge_kmem) and here during offlining. * * The idea is that that only the _last_ uncharge which sees * the dead memcg will drop the last reference. An additional * reference is taken here before the group is marked dead * which is then paired with css_put during uncharge resp. here. * * Although this might sound strange as this path is called from * css_offline() when the referencemight have dropped down to 0 * and shouldn't be incremented anymore (css_tryget would fail) * we do not have other options because of the kmem allocations * lifetime. */ css_get(&memcg->css); memcg_kmem_mark_dead(memcg); if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0) return; if (memcg_kmem_test_and_clear_dead(memcg)) css_put(&memcg->css); } #else static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) { return 0; } static void memcg_destroy_kmem(struct mem_cgroup *memcg) { } static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) { } #endif static struct cftype mem_cgroup_files[] = { { .name = "usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), .read = mem_cgroup_read, .register_event = mem_cgroup_usage_register_event, .unregister_event = mem_cgroup_usage_unregister_event, }, { .name = "max_usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, { .name = "limit_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT), .write_string = mem_cgroup_write, .read = mem_cgroup_read, }, { .name = "soft_limit_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), .write_string = mem_cgroup_write, .read = mem_cgroup_read, }, { .name = "failcnt", .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, { .name = "stat", .read_seq_string = memcg_stat_show, }, { .name = "force_empty", .trigger = mem_cgroup_force_empty_write, }, { .name = "use_hierarchy", .flags = CFTYPE_INSANE, .write_u64 = mem_cgroup_hierarchy_write, .read_u64 = mem_cgroup_hierarchy_read, }, { .name = "swappiness", .read_u64 = mem_cgroup_swappiness_read, .write_u64 = mem_cgroup_swappiness_write, }, { .name = "move_charge_at_immigrate", .read_u64 = mem_cgroup_move_charge_read, .write_u64 = mem_cgroup_move_charge_write, }, { .name = "oom_control", .read_map = mem_cgroup_oom_control_read, .write_u64 = mem_cgroup_oom_control_write, .register_event = mem_cgroup_oom_register_event, .unregister_event = mem_cgroup_oom_unregister_event, .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), }, { .name = "pressure_level", .register_event = vmpressure_register_event, .unregister_event = vmpressure_unregister_event, }, #ifdef CONFIG_NUMA { .name = "numa_stat", .read_seq_string = memcg_numa_stat_show, }, #endif #ifdef CONFIG_MEMCG_KMEM { .name = "kmem.limit_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), .write_string = mem_cgroup_write, .read = mem_cgroup_read, }, { .name = "kmem.usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), .read = mem_cgroup_read, }, { .name = "kmem.failcnt", .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, { .name = "kmem.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, #ifdef CONFIG_SLABINFO { .name = "kmem.slabinfo", .read_seq_string = mem_cgroup_slabinfo_read, }, #endif #endif { }, /* terminate */ }; #ifdef CONFIG_MEMCG_SWAP static struct cftype memsw_cgroup_files[] = { { .name = "memsw.usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), .read = mem_cgroup_read, .register_event = mem_cgroup_usage_register_event, .unregister_event = mem_cgroup_usage_unregister_event, }, { .name = "memsw.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, { .name = "memsw.limit_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), .write_string = mem_cgroup_write, .read = mem_cgroup_read, }, { .name = "memsw.failcnt", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), .trigger = mem_cgroup_reset, .read = mem_cgroup_read, }, { }, /* terminate */ }; #endif static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn; struct mem_cgroup_per_zone *mz; int zone, tmp = node; /* * This routine is called against possible nodes. * But it's BUG to call kmalloc() against offline node. * * TODO: this routine can waste much memory for nodes which will * never be onlined. It's better to use memory hotplug callback * function. */ if (!node_state(node, N_NORMAL_MEMORY)) tmp = -1; pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp); if (!pn) return 1; for (zone = 0; zone < MAX_NR_ZONES; zone++) { mz = &pn->zoneinfo[zone]; lruvec_init(&mz->lruvec); mz->memcg = memcg; } memcg->nodeinfo[node] = pn; return 0; } static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node) { kfree(memcg->nodeinfo[node]); } static struct mem_cgroup *mem_cgroup_alloc(void) { struct mem_cgroup *memcg; size_t size = memcg_size(); /* Can be very big if nr_node_ids is very big */ if (size < PAGE_SIZE) memcg = kzalloc(size, GFP_KERNEL); else memcg = vzalloc(size); if (!memcg) return NULL; memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu); if (!memcg->stat) goto out_free; spin_lock_init(&memcg->pcp_counter_lock); return memcg; out_free: if (size < PAGE_SIZE) kfree(memcg); else vfree(memcg); return NULL; } /* * At destroying mem_cgroup, references from swap_cgroup can remain. * (scanning all at force_empty is too costly...) * * Instead of clearing all references at force_empty, we remember * the number of reference from swap_cgroup and free mem_cgroup when * it goes down to 0. * * Removal of cgroup itself succeeds regardless of refs from swap. */ static void __mem_cgroup_free(struct mem_cgroup *memcg) { int node; size_t size = memcg_size(); free_css_id(&mem_cgroup_subsys, &memcg->css); for_each_node(node) free_mem_cgroup_per_zone_info(memcg, node); free_percpu(memcg->stat); /* * We need to make sure that (at least for now), the jump label * destruction code runs outside of the cgroup lock. This is because * get_online_cpus(), which is called from the static_branch update, * can't be called inside the cgroup_lock. cpusets are the ones * enforcing this dependency, so if they ever change, we might as well. * * schedule_work() will guarantee this happens. Be careful if you need * to move this code around, and make sure it is outside * the cgroup_lock. */ disarm_static_keys(memcg); if (size < PAGE_SIZE) kfree(memcg); else vfree(memcg); } /* * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled. */ struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg) { if (!memcg->res.parent) return NULL; return mem_cgroup_from_res_counter(memcg->res.parent, res); } EXPORT_SYMBOL(parent_mem_cgroup); static struct cgroup_subsys_state * __ref mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) { struct mem_cgroup *memcg; long error = -ENOMEM; int node; memcg = mem_cgroup_alloc(); if (!memcg) return ERR_PTR(error); for_each_node(node) if (alloc_mem_cgroup_per_zone_info(memcg, node)) goto free_out; /* root ? */ if (parent_css == NULL) { root_mem_cgroup = memcg; res_counter_init(&memcg->res, NULL); res_counter_init(&memcg->memsw, NULL); res_counter_init(&memcg->kmem, NULL); } memcg->last_scanned_node = MAX_NUMNODES; INIT_LIST_HEAD(&memcg->oom_notify); memcg->move_charge_at_immigrate = 0; mutex_init(&memcg->thresholds_lock); spin_lock_init(&memcg->move_lock); vmpressure_init(&memcg->vmpressure); spin_lock_init(&memcg->soft_lock); return &memcg->css; free_out: __mem_cgroup_free(memcg); return ERR_PTR(error); } static int mem_cgroup_css_online(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css)); int error = 0; if (!parent) return 0; mutex_lock(&memcg_create_mutex); memcg->use_hierarchy = parent->use_hierarchy; memcg->oom_kill_disable = parent->oom_kill_disable; memcg->swappiness = mem_cgroup_swappiness(parent); if (parent->use_hierarchy) { res_counter_init(&memcg->res, &parent->res); res_counter_init(&memcg->memsw, &parent->memsw); res_counter_init(&memcg->kmem, &parent->kmem); /* * No need to take a reference to the parent because cgroup * core guarantees its existence. */ } else { res_counter_init(&memcg->res, NULL); res_counter_init(&memcg->memsw, NULL); res_counter_init(&memcg->kmem, NULL); /* * Deeper hierachy with use_hierarchy == false doesn't make * much sense so let cgroup subsystem know about this * unfortunate state in our controller. */ if (parent != root_mem_cgroup) mem_cgroup_subsys.broken_hierarchy = true; } error = memcg_init_kmem(memcg, &mem_cgroup_subsys); mutex_unlock(&memcg_create_mutex); return error; } /* * Announce all parents that a group from their hierarchy is gone. */ static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg) { struct mem_cgroup *parent = memcg; while ((parent = parent_mem_cgroup(parent))) mem_cgroup_iter_invalidate(parent); /* * if the root memcg is not hierarchical we have to check it * explicitely. */ if (!root_mem_cgroup->use_hierarchy) mem_cgroup_iter_invalidate(root_mem_cgroup); } static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); kmem_cgroup_css_offline(memcg); mem_cgroup_invalidate_reclaim_iterators(memcg); mem_cgroup_reparent_charges(memcg); if (memcg->soft_contributed) { while ((memcg = parent_mem_cgroup(memcg))) atomic_dec(&memcg->children_in_excess); if (memcg != root_mem_cgroup && !root_mem_cgroup->use_hierarchy) atomic_dec(&root_mem_cgroup->children_in_excess); } mem_cgroup_destroy_all_caches(memcg); vmpressure_cleanup(&memcg->vmpressure); } static void mem_cgroup_css_free(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); memcg_destroy_kmem(memcg); __mem_cgroup_free(memcg); } #ifdef CONFIG_MMU /* Handlers for move charge at task migration. */ #define PRECHARGE_COUNT_AT_ONCE 256 static int mem_cgroup_do_precharge(unsigned long count) { int ret = 0; int batch_count = PRECHARGE_COUNT_AT_ONCE; struct mem_cgroup *memcg = mc.to; if (mem_cgroup_is_root(memcg)) { mc.precharge += count; /* we don't need css_get for root */ return ret; } /* try to charge at once */ if (count > 1) { struct res_counter *dummy; /* * "memcg" cannot be under rmdir() because we've already checked * by cgroup_lock_live_cgroup() that it is not removed and we * are still under the same cgroup_mutex. So we can postpone * css_get(). */ if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy)) goto one_by_one; if (do_swap_account && res_counter_charge(&memcg->memsw, PAGE_SIZE * count, &dummy)) { res_counter_uncharge(&memcg->res, PAGE_SIZE * count); goto one_by_one; } mc.precharge += count; return ret; } one_by_one: /* fall back to one by one charge */ while (count--) { if (signal_pending(current)) { ret = -EINTR; break; } if (!batch_count--) { batch_count = PRECHARGE_COUNT_AT_ONCE; cond_resched(); } ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, 1, &memcg, false); if (ret) /* mem_cgroup_clear_mc() will do uncharge later */ return ret; mc.precharge++; } return ret; } /** * get_mctgt_type - get target type of moving charge * @vma: the vma the pte to be checked belongs * @addr: the address corresponding to the pte to be checked * @ptent: the pte to be checked * @target: the pointer the target page or swap ent will be stored(can be NULL) * * Returns * 0(MC_TARGET_NONE): if the pte is not a target for move charge. * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for * move charge. if @target is not NULL, the page is stored in target->page * with extra refcnt got(Callers should handle it). * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a * target for charge migration. if @target is not NULL, the entry is stored * in target->ent. * * Called with pte lock held. */ union mc_target { struct page *page; swp_entry_t ent; }; enum mc_target_type { MC_TARGET_NONE = 0, MC_TARGET_PAGE, MC_TARGET_SWAP, }; static struct page *mc_handle_present_pte(struct vm_area_struct *vma, unsigned long addr, pte_t ptent) { struct page *page = vm_normal_page(vma, addr, ptent); if (!page || !page_mapped(page)) return NULL; if (PageAnon(page)) { /* we don't move shared anon */ if (!move_anon()) return NULL; } else if (!move_file()) /* we ignore mapcount for file pages */ return NULL; if (!get_page_unless_zero(page)) return NULL; return page; } #ifdef CONFIG_SWAP static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, unsigned long addr, pte_t ptent, swp_entry_t *entry) { struct page *page = NULL; swp_entry_t ent = pte_to_swp_entry(ptent); if (!move_anon() || non_swap_entry(ent)) return NULL; /* * Because lookup_swap_cache() updates some statistics counter, * we call find_get_page() with swapper_space directly. */ page = find_get_page(swap_address_space(ent), ent.val); if (do_swap_account) entry->val = ent.val; return page; } #else static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, unsigned long addr, pte_t ptent, swp_entry_t *entry) { return NULL; } #endif static struct page *mc_handle_file_pte(struct vm_area_struct *vma, unsigned long addr, pte_t ptent, swp_entry_t *entry) { struct page *page = NULL; struct address_space *mapping; pgoff_t pgoff; if (!vma->vm_file) /* anonymous vma */ return NULL; if (!move_file()) return NULL; mapping = vma->vm_file->f_mapping; if (pte_none(ptent)) pgoff = linear_page_index(vma, addr); else /* pte_file(ptent) is true */ pgoff = pte_to_pgoff(ptent); /* page is moved even if it's not RSS of this task(page-faulted). */ page = find_get_page(mapping, pgoff); #ifdef CONFIG_SWAP /* shmem/tmpfs may report page out on swap: account for that too. */ if (radix_tree_exceptional_entry(page)) { swp_entry_t swap = radix_to_swp_entry(page); if (do_swap_account) *entry = swap; page = find_get_page(swap_address_space(swap), swap.val); } #endif return page; } static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma, unsigned long addr, pte_t ptent, union mc_target *target) { struct page *page = NULL; struct page_cgroup *pc; enum mc_target_type ret = MC_TARGET_NONE; swp_entry_t ent = { .val = 0 }; if (pte_present(ptent)) page = mc_handle_present_pte(vma, addr, ptent); else if (is_swap_pte(ptent)) page = mc_handle_swap_pte(vma, addr, ptent, &ent); else if (pte_none(ptent) || pte_file(ptent)) page = mc_handle_file_pte(vma, addr, ptent, &ent); if (!page && !ent.val) return ret; if (page) { pc = lookup_page_cgroup(page); /* * Do only loose check w/o page_cgroup lock. * mem_cgroup_move_account() checks the pc is valid or not under * the lock. */ if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) { ret = MC_TARGET_PAGE; if (target) target->page = page; } if (!ret || !target) put_page(page); } /* There is a swap entry and a page doesn't exist or isn't charged */ if (ent.val && !ret && mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) { ret = MC_TARGET_SWAP; if (target) target->ent = ent; } return ret; } #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* * We don't consider swapping or file mapped pages because THP does not * support them for now. * Caller should make sure that pmd_trans_huge(pmd) is true. */ static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, unsigned long addr, pmd_t pmd, union mc_target *target) { struct page *page = NULL; struct page_cgroup *pc; enum mc_target_type ret = MC_TARGET_NONE; page = pmd_page(pmd); VM_BUG_ON(!page || !PageHead(page)); if (!move_anon()) return ret; pc = lookup_page_cgroup(page); if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) { ret = MC_TARGET_PAGE; if (target) { get_page(page); target->page = page; } } return ret; } #else static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, unsigned long addr, pmd_t pmd, union mc_target *target) { return MC_TARGET_NONE; } #endif static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { struct vm_area_struct *vma = walk->private; pte_t *pte; spinlock_t *ptl; if (pmd_trans_huge_lock(pmd, vma) == 1) { if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) mc.precharge += HPAGE_PMD_NR; spin_unlock(&vma->vm_mm->page_table_lock); return 0; } if (pmd_trans_unstable(pmd)) return 0; pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) if (get_mctgt_type(vma, addr, *pte, NULL)) mc.precharge++; /* increment precharge temporarily */ pte_unmap_unlock(pte - 1, ptl); cond_resched(); return 0; } static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) { unsigned long precharge; struct vm_area_struct *vma; down_read(&mm->mmap_sem); for (vma = mm->mmap; vma; vma = vma->vm_next) { struct mm_walk mem_cgroup_count_precharge_walk = { .pmd_entry = mem_cgroup_count_precharge_pte_range, .mm = mm, .private = vma, }; if (is_vm_hugetlb_page(vma)) continue; walk_page_range(vma->vm_start, vma->vm_end, &mem_cgroup_count_precharge_walk); } up_read(&mm->mmap_sem); precharge = mc.precharge; mc.precharge = 0; return precharge; } static int mem_cgroup_precharge_mc(struct mm_struct *mm) { unsigned long precharge = mem_cgroup_count_precharge(mm); VM_BUG_ON(mc.moving_task); mc.moving_task = current; return mem_cgroup_do_precharge(precharge); } /* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */ static void __mem_cgroup_clear_mc(void) { struct mem_cgroup *from = mc.from; struct mem_cgroup *to = mc.to; int i; /* we must uncharge all the leftover precharges from mc.to */ if (mc.precharge) { __mem_cgroup_cancel_charge(mc.to, mc.precharge); mc.precharge = 0; } /* * we didn't uncharge from mc.from at mem_cgroup_move_account(), so * we must uncharge here. */ if (mc.moved_charge) { __mem_cgroup_cancel_charge(mc.from, mc.moved_charge); mc.moved_charge = 0; } /* we must fixup refcnts and charges */ if (mc.moved_swap) { /* uncharge swap account from the old cgroup */ if (!mem_cgroup_is_root(mc.from)) res_counter_uncharge(&mc.from->memsw, PAGE_SIZE * mc.moved_swap); for (i = 0; i < mc.moved_swap; i++) css_put(&mc.from->css); if (!mem_cgroup_is_root(mc.to)) { /* * we charged both to->res and to->memsw, so we should * uncharge to->res. */ res_counter_uncharge(&mc.to->res, PAGE_SIZE * mc.moved_swap); } /* we've already done css_get(mc.to) */ mc.moved_swap = 0; } memcg_oom_recover(from); memcg_oom_recover(to); wake_up_all(&mc.waitq); } static void mem_cgroup_clear_mc(void) { struct mem_cgroup *from = mc.from; /* * we must clear moving_task before waking up waiters at the end of * task migration. */ mc.moving_task = NULL; __mem_cgroup_clear_mc(); spin_lock(&mc.lock); mc.from = NULL; mc.to = NULL; spin_unlock(&mc.lock); mem_cgroup_end_move(from); } static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { struct task_struct *p = cgroup_taskset_first(tset); int ret = 0; struct mem_cgroup *memcg = mem_cgroup_from_css(css); unsigned long move_charge_at_immigrate; /* * We are now commited to this value whatever it is. Changes in this * tunable will only affect upcoming migrations, not the current one. * So we need to save it, and keep it going. */ move_charge_at_immigrate = memcg->move_charge_at_immigrate; if (move_charge_at_immigrate) { struct mm_struct *mm; struct mem_cgroup *from = mem_cgroup_from_task(p); VM_BUG_ON(from == memcg); mm = get_task_mm(p); if (!mm) return 0; /* We move charges only when we move a owner of the mm */ if (mm->owner == p) { VM_BUG_ON(mc.from); VM_BUG_ON(mc.to); VM_BUG_ON(mc.precharge); VM_BUG_ON(mc.moved_charge); VM_BUG_ON(mc.moved_swap); mem_cgroup_start_move(from); spin_lock(&mc.lock); mc.from = from; mc.to = memcg; mc.immigrate_flags = move_charge_at_immigrate; spin_unlock(&mc.lock); /* We set mc.moving_task later */ ret = mem_cgroup_precharge_mc(mm); if (ret) mem_cgroup_clear_mc(); } mmput(mm); } return ret; } static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { mem_cgroup_clear_mc(); } static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { int ret = 0; struct vm_area_struct *vma = walk->private; pte_t *pte; spinlock_t *ptl; enum mc_target_type target_type; union mc_target target; struct page *page; struct page_cgroup *pc; /* * We don't take compound_lock() here but no race with splitting thp * happens because: * - if pmd_trans_huge_lock() returns 1, the relevant thp is not * under splitting, which means there's no concurrent thp split, * - if another thread runs into split_huge_page() just after we * entered this if-block, the thread must wait for page table lock * to be unlocked in __split_huge_page_splitting(), where the main * part of thp split is not executed yet. */ if (pmd_trans_huge_lock(pmd, vma) == 1) { if (mc.precharge < HPAGE_PMD_NR) { spin_unlock(&vma->vm_mm->page_table_lock); return 0; } target_type = get_mctgt_type_thp(vma, addr, *pmd, &target); if (target_type == MC_TARGET_PAGE) { page = target.page; if (!isolate_lru_page(page)) { pc = lookup_page_cgroup(page); if (!mem_cgroup_move_account(page, HPAGE_PMD_NR, pc, mc.from, mc.to)) { mc.precharge -= HPAGE_PMD_NR; mc.moved_charge += HPAGE_PMD_NR; } putback_lru_page(page); } put_page(page); } spin_unlock(&vma->vm_mm->page_table_lock); return 0; } if (pmd_trans_unstable(pmd)) return 0; retry: pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; addr += PAGE_SIZE) { pte_t ptent = *(pte++); swp_entry_t ent; if (!mc.precharge) break; switch (get_mctgt_type(vma, addr, ptent, &target)) { case MC_TARGET_PAGE: page = target.page; if (isolate_lru_page(page)) goto put; pc = lookup_page_cgroup(page); if (!mem_cgroup_move_account(page, 1, pc, mc.from, mc.to)) { mc.precharge--; /* we uncharge from mc.from later. */ mc.moved_charge++; } putback_lru_page(page); put: /* get_mctgt_type() gets the page */ put_page(page); break; case MC_TARGET_SWAP: ent = target.ent; if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) { mc.precharge--; /* we fixup refcnts and charges later. */ mc.moved_swap++; } break; default: break; } } pte_unmap_unlock(pte - 1, ptl); cond_resched(); if (addr != end) { /* * We have consumed all precharges we got in can_attach(). * We try charge one by one, but don't do any additional * charges to mc.to if we have failed in charge once in attach() * phase. */ ret = mem_cgroup_do_precharge(1); if (!ret) goto retry; } return ret; } static void mem_cgroup_move_charge(struct mm_struct *mm) { struct vm_area_struct *vma; lru_add_drain_all(); retry: if (unlikely(!down_read_trylock(&mm->mmap_sem))) { /* * Someone who are holding the mmap_sem might be waiting in * waitq. So we cancel all extra charges, wake up all waiters, * and retry. Because we cancel precharges, we might not be able * to move enough charges, but moving charge is a best-effort * feature anyway, so it wouldn't be a big problem. */ __mem_cgroup_clear_mc(); cond_resched(); goto retry; } for (vma = mm->mmap; vma; vma = vma->vm_next) { int ret; struct mm_walk mem_cgroup_move_charge_walk = { .pmd_entry = mem_cgroup_move_charge_pte_range, .mm = mm, .private = vma, }; if (is_vm_hugetlb_page(vma)) continue; ret = walk_page_range(vma->vm_start, vma->vm_end, &mem_cgroup_move_charge_walk); if (ret) /* * means we have consumed all precharges and failed in * doing additional charge. Just abandon here. */ break; } up_read(&mm->mmap_sem); } static void mem_cgroup_move_task(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { struct task_struct *p = cgroup_taskset_first(tset); struct mm_struct *mm = get_task_mm(p); if (mm) { if (mc.to) mem_cgroup_move_charge(mm); mmput(mm); } if (mc.to) mem_cgroup_clear_mc(); } #else /* !CONFIG_MMU */ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { return 0; } static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { } static void mem_cgroup_move_task(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { } #endif /* * Cgroup retains root cgroups across [un]mount cycles making it necessary * to verify sane_behavior flag on each mount attempt. */ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) { /* * use_hierarchy is forced with sane_behavior. cgroup core * guarantees that @root doesn't have any children, so turning it * on for the root memcg is enough. */ if (cgroup_sane_behavior(root_css->cgroup)) mem_cgroup_from_css(root_css)->use_hierarchy = true; } struct cgroup_subsys mem_cgroup_subsys = { .name = "memory", .subsys_id = mem_cgroup_subsys_id, .css_alloc = mem_cgroup_css_alloc, .css_online = mem_cgroup_css_online, .css_offline = mem_cgroup_css_offline, .css_free = mem_cgroup_css_free, .can_attach = mem_cgroup_can_attach, .cancel_attach = mem_cgroup_cancel_attach, .attach = mem_cgroup_move_task, .bind = mem_cgroup_bind, .base_cftypes = mem_cgroup_files, .early_init = 0, .use_id = 1, }; #ifdef CONFIG_MEMCG_SWAP static int __init enable_swap_account(char *s) { if (!strcmp(s, "1")) really_do_swap_account = 1; else if (!strcmp(s, "0")) really_do_swap_account = 0; return 1; } __setup("swapaccount=", enable_swap_account); static void __init memsw_file_init(void) { WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys, memsw_cgroup_files)); } static void __init enable_swap_cgroup(void) { if (!mem_cgroup_disabled() && really_do_swap_account) { do_swap_account = 1; memsw_file_init(); } } #else static void __init enable_swap_cgroup(void) { } #endif /* * subsys_initcall() for memory controller. * * Some parts like hotcpu_notifier() have to be initialized from this context * because of lock dependencies (cgroup_lock -> cpu hotplug) but basically * everything that doesn't depend on a specific mem_cgroup structure should * be initialized from here. */ static int __init mem_cgroup_init(void) { hotcpu_notifier(memcg_cpu_hotplug_callback, 0); enable_swap_cgroup(); memcg_stock_init(); return 0; } subsys_initcall(mem_cgroup_init);