/* 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 * * 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; #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 /* * Statistics for memory cgroup. */ enum mem_cgroup_stat_index { /* * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss. */ MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */ MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */ MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */ MEM_CGROUP_STAT_SWAP, /* # of pages, swapped out */ MEM_CGROUP_STAT_NSTATS, }; static const char * const mem_cgroup_stat_names[] = { "cache", "rss", "mapped_file", "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", }; /* * 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 { /* css_id of the last scanned hierarchy member */ int position; /* scan generation, increased every round-trip */ unsigned int generation; }; /* * per-zone information in memory controller. */ struct mem_cgroup_per_zone { struct lruvec lruvec; unsigned long lru_size[NR_LRU_LISTS]; struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1]; struct rb_node tree_node; /* RB tree node */ unsigned long long usage_in_excess;/* Set to the value by which */ /* the soft limit is exceeded*/ bool on_tree; struct mem_cgroup *memcg; /* Back pointer, we cannot */ /* use container_of */ }; struct mem_cgroup_per_node { struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES]; }; struct mem_cgroup_lru_info { struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES]; }; /* * Cgroups above their limits are maintained in a RB-Tree, independent of * their hierarchy representation */ struct mem_cgroup_tree_per_zone { struct rb_root rb_root; spinlock_t lock; }; struct mem_cgroup_tree_per_node { struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES]; }; struct mem_cgroup_tree { struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES]; }; static struct mem_cgroup_tree soft_limit_tree __read_mostly; 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; union { /* * the counter to account for mem+swap usage. */ struct res_counter memsw; /* * rcu_freeing is used only when freeing struct mem_cgroup, * so put it into a union to avoid wasting more memory. * It must be disjoint from the css field. It could be * in a union with the res field, but res plays a much * larger part in mem_cgroup life than memsw, and might * be of interest, even at time of free, when debugging. * So share rcu_head with the less interesting memsw. */ struct rcu_head rcu_freeing; /* * We also need some space for a worker in deferred freeing. * By the time we call it, rcu_freeing is no longer in use. */ struct work_struct work_freeing; }; /* * Per cgroup active and inactive list, similar to the * per zone LRU lists. */ struct mem_cgroup_lru_info info; int last_scanned_node; #if MAX_NUMNODES > 1 nodemask_t scan_nodes; atomic_t numainfo_events; atomic_t numainfo_updating; #endif /* * Should the accounting and control be hierarchical, per subtree? */ bool use_hierarchy; bool oom_lock; atomic_t under_oom; atomic_t refcnt; 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; #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET) struct tcp_memcontrol tcp_mem; #endif }; /* Stuffs for move charges at task migration. */ /* * Types of charges to be moved. "move_charge_at_immitgrate" is 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 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.to->move_charge_at_immigrate); } static bool move_file(void) { return test_bit(MOVE_CHARGE_TYPE_FILE, &mc.to->move_charge_at_immigrate); } /* * 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 #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2 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 */ #define _MEM (0) #define _MEMSWAP (1) #define _OOM_TYPE (2) #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) static void mem_cgroup_get(struct mem_cgroup *memcg); static void mem_cgroup_put(struct mem_cgroup *memcg); static inline struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s) { return container_of(s, struct mem_cgroup, css); } static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) { return (memcg == root_mem_cgroup); } /* 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)); mem_cgroup_get(sk->sk_cgrp->memcg); 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)) { mem_cgroup_get(memcg); 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; mem_cgroup_put(memcg); } } 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 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) { return &memcg->info.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); } static struct mem_cgroup_tree_per_zone * soft_limit_tree_node_zone(int nid, int zid) { return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; } static struct mem_cgroup_tree_per_zone * soft_limit_tree_from_page(struct page *page) { int nid = page_to_nid(page); int zid = page_zonenum(page); return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid]; } static void __mem_cgroup_insert_exceeded(struct mem_cgroup *memcg, struct mem_cgroup_per_zone *mz, struct mem_cgroup_tree_per_zone *mctz, unsigned long long new_usage_in_excess) { struct rb_node **p = &mctz->rb_root.rb_node; struct rb_node *parent = NULL; struct mem_cgroup_per_zone *mz_node; if (mz->on_tree) return; mz->usage_in_excess = new_usage_in_excess; if (!mz->usage_in_excess) return; while (*p) { parent = *p; mz_node = rb_entry(parent, struct mem_cgroup_per_zone, tree_node); if (mz->usage_in_excess < mz_node->usage_in_excess) p = &(*p)->rb_left; /* * We can't avoid mem cgroups that are over their soft * limit by the same amount */ else if (mz->usage_in_excess >= mz_node->usage_in_excess) p = &(*p)->rb_right; } rb_link_node(&mz->tree_node, parent, p); rb_insert_color(&mz->tree_node, &mctz->rb_root); mz->on_tree = true; } static void __mem_cgroup_remove_exceeded(struct mem_cgroup *memcg, struct mem_cgroup_per_zone *mz, struct mem_cgroup_tree_per_zone *mctz) { if (!mz->on_tree) return; rb_erase(&mz->tree_node, &mctz->rb_root); mz->on_tree = false; } static void mem_cgroup_remove_exceeded(struct mem_cgroup *memcg, struct mem_cgroup_per_zone *mz, struct mem_cgroup_tree_per_zone *mctz) { spin_lock(&mctz->lock); __mem_cgroup_remove_exceeded(memcg, mz, mctz); spin_unlock(&mctz->lock); } static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page) { unsigned long long excess; struct mem_cgroup_per_zone *mz; struct mem_cgroup_tree_per_zone *mctz; int nid = page_to_nid(page); int zid = page_zonenum(page); mctz = soft_limit_tree_from_page(page); /* * Necessary to update all ancestors when hierarchy is used. * because their event counter is not touched. */ for (; memcg; memcg = parent_mem_cgroup(memcg)) { mz = mem_cgroup_zoneinfo(memcg, nid, zid); excess = res_counter_soft_limit_excess(&memcg->res); /* * We have to update the tree if mz is on RB-tree or * mem is over its softlimit. */ if (excess || mz->on_tree) { spin_lock(&mctz->lock); /* if on-tree, remove it */ if (mz->on_tree) __mem_cgroup_remove_exceeded(memcg, mz, mctz); /* * Insert again. mz->usage_in_excess will be updated. * If excess is 0, no tree ops. */ __mem_cgroup_insert_exceeded(memcg, mz, mctz, excess); spin_unlock(&mctz->lock); } } } static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) { int node, zone; struct mem_cgroup_per_zone *mz; struct mem_cgroup_tree_per_zone *mctz; for_each_node(node) { for (zone = 0; zone < MAX_NR_ZONES; zone++) { mz = mem_cgroup_zoneinfo(memcg, node, zone); mctz = soft_limit_tree_node_zone(node, zone); mem_cgroup_remove_exceeded(memcg, mz, mctz); } } } static struct mem_cgroup_per_zone * __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) { struct rb_node *rightmost = NULL; struct mem_cgroup_per_zone *mz; retry: mz = NULL; rightmost = rb_last(&mctz->rb_root); if (!rightmost) goto done; /* Nothing to reclaim from */ mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node); /* * Remove the node now but someone else can add it back, * we will to add it back at the end of reclaim to its correct * position in the tree. */ __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz); if (!res_counter_soft_limit_excess(&mz->memcg->res) || !css_tryget(&mz->memcg->css)) goto retry; done: return mz; } static struct mem_cgroup_per_zone * mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz) { struct mem_cgroup_per_zone *mz; spin_lock(&mctz->lock); mz = __mem_cgroup_largest_soft_limit_node(mctz); spin_unlock(&mctz->lock); return mz; } /* * 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, 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); /* 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_HIGH_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; } /* * 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_tree(memcg, page); #if MAX_NUMNODES > 1 if (unlikely(do_numainfo)) atomic_inc(&memcg->numainfo_events); #endif } else preempt_enable(); } struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont) { return mem_cgroup_from_css( cgroup_subsys_state(cont, mem_cgroup_subsys_id)); } 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_subsys_state(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; } /** * 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 * * 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(struct mem_cgroup *root, struct mem_cgroup *prev, struct mem_cgroup_reclaim_cookie *reclaim) { struct mem_cgroup *memcg = NULL; int id = 0; if (mem_cgroup_disabled()) return NULL; if (!root) root = root_mem_cgroup; if (prev && !reclaim) id = css_id(&prev->css); if (prev && prev != root) css_put(&prev->css); if (!root->use_hierarchy && root != root_mem_cgroup) { if (prev) return NULL; return root; } while (!memcg) { struct mem_cgroup_reclaim_iter *uninitialized_var(iter); struct cgroup_subsys_state *css; 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) return NULL; id = iter->position; } rcu_read_lock(); css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id); if (css) { if (css == &root->css || css_tryget(css)) memcg = mem_cgroup_from_css(css); } else id = 0; rcu_read_unlock(); if (reclaim) { iter->position = id; if (!css) iter->generation++; else if (!prev && memcg) reclaim->generation = iter->generation; } if (prev && !css) return NULL; } 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; if (!mm) return; rcu_read_lock(); memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); if (unlikely(!memcg)) goto out; switch (idx) { case PGFAULT: this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]); break; case PGMAJFAULT: this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]); break; default: BUG(); } out: rcu_read_unlock(); } 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 css_is_ancestor(&memcg->css, &root_memcg->css); } 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; } int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg) { int ret; struct mem_cgroup *curr = NULL; struct task_struct *p; 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. */ task_lock(task); curr = mem_cgroup_from_task(task); if (curr) css_get(&curr->css); task_unlock(task); } if (!curr) return 0; /* * 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; } int mem_cgroup_inactive_file_is_low(struct lruvec *lruvec) { unsigned long active; unsigned long inactive; inactive = mem_cgroup_get_lru_size(lruvec, LRU_INACTIVE_FILE); active = mem_cgroup_get_lru_size(lruvec, LRU_ACTIVE_FILE); return (active > inactive); } #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) { struct cgroup *cgrp = memcg->css.cgroup; /* root ? */ if (cgrp->parent == NULL) 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); } /** * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode. * @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; if (!memcg || !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(); printk(KERN_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 */ printk(KERN_CONT " as a result of limit of %s\n", memcg_name); done: printk(KERN_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)); printk(KERN_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)); } /* * 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; } 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, 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)) { 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 cgroup *cgroup = iter->css.cgroup; struct cgroup_iter it; struct task_struct *task; cgroup_iter_start(cgroup, &it); while ((task = cgroup_iter_next(cgroup, &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: cgroup_iter_end(cgroup, &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); } } cgroup_iter_end(cgroup, &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; } /** * 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; } #if MAX_NUMNODES > 1 /* * 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_HIGH_MEMORY]; for_each_node_mask(nid, node_states[N_HIGH_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; } /* * Check all nodes whether it contains reclaimable pages or not. * For quick scan, we make use of scan_nodes. This will allow us to skip * unused nodes. But scan_nodes is lazily updated and may not cotain * enough new information. We need to do double check. */ static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) { int nid; /* * quick check...making use of scan_node. * We can skip unused nodes. */ if (!nodes_empty(memcg->scan_nodes)) { for (nid = first_node(memcg->scan_nodes); nid < MAX_NUMNODES; nid = next_node(nid, memcg->scan_nodes)) { if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) return true; } } /* * Check rest of nodes. */ for_each_node_state(nid, N_HIGH_MEMORY) { if (node_isset(nid, memcg->scan_nodes)) continue; if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap)) return true; } return false; } #else int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) { return 0; } static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) { return test_mem_cgroup_node_reclaimable(memcg, 0, noswap); } #endif static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, struct zone *zone, gfp_t gfp_mask, unsigned long *total_scanned) { struct mem_cgroup *victim = NULL; int total = 0; int loop = 0; unsigned long excess; unsigned long nr_scanned; struct mem_cgroup_reclaim_cookie reclaim = { .zone = zone, .priority = 0, }; excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT; while (1) { victim = mem_cgroup_iter(root_memcg, victim, &reclaim); if (!victim) { loop++; if (loop >= 2) { /* * If we have not been able to reclaim * anything, it might because there are * no reclaimable pages under this hierarchy */ if (!total) break; /* * We want to do more targeted reclaim. * excess >> 2 is not to excessive so as to * reclaim too much, nor too less that we keep * coming back to reclaim from this cgroup */ if (total >= (excess >> 2) || (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) break; } continue; } if (!mem_cgroup_reclaimable(victim, false)) continue; total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false, zone, &nr_scanned); *total_scanned += nr_scanned; if (!res_counter_soft_limit_excess(&root_memcg->res)) break; } mem_cgroup_iter_break(root_memcg, victim); return total; } /* * Check OOM-Killer is already running under our hierarchy. * If someone is running, return false. * Has to be called with memcg_oom_lock */ static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg) { struct mem_cgroup *iter, *failed = NULL; 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) return true; /* * 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; } return false; } /* * Has to be called with memcg_oom_lock */ static int mem_cgroup_oom_unlock(struct mem_cgroup *memcg) { struct mem_cgroup *iter; for_each_mem_cgroup_tree(iter, memcg) iter->oom_lock = false; return 0; } 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 DEFINE_SPINLOCK(memcg_oom_lock); 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) { /* 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. returns false if we should exit memory-reclaim loop. */ static bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask, int order) { struct oom_wait_info owait; bool locked, need_to_kill; 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); need_to_kill = true; mem_cgroup_mark_under_oom(memcg); /* At first, try to OOM lock hierarchy under memcg.*/ spin_lock(&memcg_oom_lock); locked = mem_cgroup_oom_lock(memcg); /* * Even if signal_pending(), we can't quit charge() loop without * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL * under OOM is always welcomed, use TASK_KILLABLE here. */ prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); if (!locked || memcg->oom_kill_disable) need_to_kill = false; if (locked) mem_cgroup_oom_notify(memcg); spin_unlock(&memcg_oom_lock); if (need_to_kill) { finish_wait(&memcg_oom_waitq, &owait.wait); mem_cgroup_out_of_memory(memcg, mask, order); } else { schedule(); finish_wait(&memcg_oom_waitq, &owait.wait); } spin_lock(&memcg_oom_lock); if (locked) mem_cgroup_oom_unlock(memcg); memcg_wakeup_oom(memcg); spin_unlock(&memcg_oom_lock); mem_cgroup_unmark_under_oom(memcg); if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current)) return false; /* Give chance to dying process */ schedule_timeout_uninterruptible(1); 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_page_stat_item 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; memcg = pc->mem_cgroup; if (unlikely(!memcg || !PageCgroupUsed(pc))) return; switch (idx) { case MEMCG_NR_FILE_MAPPED: idx = MEM_CGROUP_STAT_FILE_MAPPED; break; default: BUG(); } 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); /* * Try to consume stocked charge on this cpu. If success, one page is consumed * from local stock and true is returned. If the stock is 0 or charges from a * cgroup which is not current target, returns false. This stock will be * refilled. */ static bool consume_stock(struct mem_cgroup *memcg) { struct memcg_stock_pcp *stock; bool ret = true; stock = &get_cpu_var(memcg_stock); if (memcg == stock->cached && stock->nr_pages) stock->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); } /* * 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 __cpuinit 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. */ CHARGE_OOM_DIE, /* the current is killed because of OOM */ }; static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages, bool oom_check) { 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); /* * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch * of regular pages (CHARGE_BATCH), or a single regular page (1). * * Never reclaim on behalf of optional batching, retry with a * single page instead. */ if (nr_pages == CHARGE_BATCH) return CHARGE_RETRY; if (!(gfp_mask & __GFP_WAIT)) return CHARGE_WOULDBLOCK; 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 && 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 we don't need to call oom-killer at el, return immediately */ if (!oom_check) return CHARGE_NOMEM; /* check OOM */ if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize))) return CHARGE_OOM_DIE; return CHARGE_RETRY; } /* * __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; VM_BUG_ON(css_is_removed(&memcg->css)); if (mem_cgroup_is_root(memcg)) goto done; if (nr_pages == 1 && consume_stock(memcg)) 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 (nr_pages == 1 && consume_stock(memcg)) { /* * It seems dagerous to access