// SPDX-License-Identifier: GPL-2.0-or-later /* 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 * * Native page reclaim * Charge lifetime sanitation * Lockless page tracking & accounting * Unified hierarchy configuration model * Copyright (C) 2015 Red Hat, Inc., Johannes Weiner */ #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 #include #include #include #include #include #include #include #include #include "internal.h" #include #include #include "slab.h" #include #include struct cgroup_subsys memory_cgrp_subsys __read_mostly; EXPORT_SYMBOL(memory_cgrp_subsys); struct mem_cgroup *root_mem_cgroup __read_mostly; #define MEM_CGROUP_RECLAIM_RETRIES 5 /* Socket memory accounting disabled? */ static bool cgroup_memory_nosocket; /* Kernel memory accounting disabled? */ static bool cgroup_memory_nokmem; /* Whether the swap controller is active */ #ifdef CONFIG_MEMCG_SWAP int do_swap_account __read_mostly; #else #define do_swap_account 0 #endif #ifdef CONFIG_CGROUP_WRITEBACK static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq); #endif /* Whether legacy memory+swap accounting is active */ static bool do_memsw_account(void) { return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account; } #define THRESHOLDS_EVENTS_TARGET 128 #define SOFTLIMIT_EVENTS_TARGET 1024 /* * Cgroups above their limits are maintained in a RB-Tree, independent of * their hierarchy representation */ struct mem_cgroup_tree_per_node { struct rb_root rb_root; struct rb_node *rb_rightmost; spinlock_t lock; }; 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; /* for OOM */ struct mem_cgroup_eventfd_list { struct list_head list; struct eventfd_ctx *eventfd; }; /* * cgroup_event represents events which userspace want to receive. */ struct mem_cgroup_event { /* * memcg which the event belongs to. */ struct mem_cgroup *memcg; /* * eventfd to signal userspace about the event. */ struct eventfd_ctx *eventfd; /* * Each of these stored in a list by the cgroup. */ struct list_head list; /* * register_event() callback will be used to add new userspace * waiter for changes related to this event. Use eventfd_signal() * on eventfd to send notification to userspace. */ int (*register_event)(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args); /* * unregister_event() callback will be called when userspace closes * the eventfd or on cgroup removing. This callback must be set, * if you want provide notification functionality. */ void (*unregister_event)(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd); /* * All fields below needed to unregister event when * userspace closes eventfd. */ poll_table pt; wait_queue_head_t *wqh; wait_queue_entry_t wait; struct work_struct remove; }; static void mem_cgroup_threshold(struct mem_cgroup *memcg); static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); /* Stuffs for move charges at task migration. */ /* * Types of charges to be moved. */ #define MOVE_ANON 0x1U #define MOVE_FILE 0x2U #define MOVE_MASK (MOVE_ANON | MOVE_FILE) /* "mc" and its members are protected by cgroup_mutex */ static struct move_charge_struct { spinlock_t lock; /* for from, to */ struct mm_struct *mm; struct mem_cgroup *from; struct mem_cgroup *to; unsigned long 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), }; /* * 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 */ enum res_type { _MEM, _MEMSWAP, _OOM_TYPE, _KMEM, _TCP, }; #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) /* * 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)) static inline bool should_force_charge(void) { return tsk_is_oom_victim(current) || fatal_signal_pending(current) || (current->flags & PF_EXITING); } /* 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; } #ifdef CONFIG_MEMCG_KMEM /* * This will be the memcg's index in each cache's ->memcg_params.memcg_caches. * The main reason for not using cgroup id for this: * 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. * * The current size of the caches array is stored in memcg_nr_cache_ids. It * will double each time we have to increase it. */ static DEFINE_IDA(memcg_cache_ida); int memcg_nr_cache_ids; /* Protects memcg_nr_cache_ids */ static DECLARE_RWSEM(memcg_cache_ids_sem); void memcg_get_cache_ids(void) { down_read(&memcg_cache_ids_sem); } void memcg_put_cache_ids(void) { up_read(&memcg_cache_ids_sem); } /* * 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 cgrp_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 * cgrp_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 MEM_CGROUP_ID_MAX /* * 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 */ DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key); EXPORT_SYMBOL(memcg_kmem_enabled_key); struct workqueue_struct *memcg_kmem_cache_wq; #endif static int memcg_shrinker_map_size; static DEFINE_MUTEX(memcg_shrinker_map_mutex); static void memcg_free_shrinker_map_rcu(struct rcu_head *head) { kvfree(container_of(head, struct memcg_shrinker_map, rcu)); } static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg, int size, int old_size) { struct memcg_shrinker_map *new, *old; int nid; lockdep_assert_held(&memcg_shrinker_map_mutex); for_each_node(nid) { old = rcu_dereference_protected( mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true); /* Not yet online memcg */ if (!old) return 0; new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid); if (!new) return -ENOMEM; /* Set all old bits, clear all new bits */ memset(new->map, (int)0xff, old_size); memset((void *)new->map + old_size, 0, size - old_size); rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new); call_rcu(&old->rcu, memcg_free_shrinker_map_rcu); } return 0; } static void memcg_free_shrinker_maps(struct mem_cgroup *memcg) { struct mem_cgroup_per_node *pn; struct memcg_shrinker_map *map; int nid; if (mem_cgroup_is_root(memcg)) return; for_each_node(nid) { pn = mem_cgroup_nodeinfo(memcg, nid); map = rcu_dereference_protected(pn->shrinker_map, true); if (map) kvfree(map); rcu_assign_pointer(pn->shrinker_map, NULL); } } static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) { struct memcg_shrinker_map *map; int nid, size, ret = 0; if (mem_cgroup_is_root(memcg)) return 0; mutex_lock(&memcg_shrinker_map_mutex); size = memcg_shrinker_map_size; for_each_node(nid) { map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid); if (!map) { memcg_free_shrinker_maps(memcg); ret = -ENOMEM; break; } rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map); } mutex_unlock(&memcg_shrinker_map_mutex); return ret; } int memcg_expand_shrinker_maps(int new_id) { int size, old_size, ret = 0; struct mem_cgroup *memcg; size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); old_size = memcg_shrinker_map_size; if (size <= old_size) return 0; mutex_lock(&memcg_shrinker_map_mutex); if (!root_mem_cgroup) goto unlock; for_each_mem_cgroup(memcg) { if (mem_cgroup_is_root(memcg)) continue; ret = memcg_expand_one_shrinker_map(memcg, size, old_size); if (ret) { mem_cgroup_iter_break(NULL, memcg); goto unlock; } } unlock: if (!ret) memcg_shrinker_map_size = size; mutex_unlock(&memcg_shrinker_map_mutex); return ret; } void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) { if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) { struct memcg_shrinker_map *map; rcu_read_lock(); map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map); /* Pairs with smp mb in shrink_slab() */ smp_mb__before_atomic(); set_bit(shrinker_id, map->map); rcu_read_unlock(); } } /** * mem_cgroup_css_from_page - css of the memcg associated with a page * @page: page of interest * * If memcg is bound to the default hierarchy, css of the memcg associated * with @page is returned. The returned css remains associated with @page * until it is released. * * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup * is returned. */ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page) { struct mem_cgroup *memcg; memcg = page->mem_cgroup; if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) memcg = root_mem_cgroup; return &memcg->css; } /** * page_cgroup_ino - return inode number of the memcg a page is charged to * @page: the page * * Look up the closest online ancestor of the memory cgroup @page is charged to * and return its inode number or 0 if @page is not charged to any cgroup. It * is safe to call this function without holding a reference to @page. * * Note, this function is inherently racy, because there is nothing to prevent * the cgroup inode from getting torn down and potentially reallocated a moment * after page_cgroup_ino() returns, so it only should be used by callers that * do not care (such as procfs interfaces). */ ino_t page_cgroup_ino(struct page *page) { struct mem_cgroup *memcg; unsigned long ino = 0; rcu_read_lock(); if (PageSlab(page) && !PageTail(page)) memcg = memcg_from_slab_page(page); else memcg = READ_ONCE(page->mem_cgroup); while (memcg && !(memcg->css.flags & CSS_ONLINE)) memcg = parent_mem_cgroup(memcg); if (memcg) ino = cgroup_ino(memcg->css.cgroup); rcu_read_unlock(); return ino; } static struct mem_cgroup_per_node * mem_cgroup_page_nodeinfo(struct mem_cgroup *memcg, struct page *page) { int nid = page_to_nid(page); return memcg->nodeinfo[nid]; } static struct mem_cgroup_tree_per_node * soft_limit_tree_node(int nid) { return soft_limit_tree.rb_tree_per_node[nid]; } static struct mem_cgroup_tree_per_node * soft_limit_tree_from_page(struct page *page) { int nid = page_to_nid(page); return soft_limit_tree.rb_tree_per_node[nid]; } static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, struct mem_cgroup_tree_per_node *mctz, unsigned long new_usage_in_excess) { struct rb_node **p = &mctz->rb_root.rb_node; struct rb_node *parent = NULL; struct mem_cgroup_per_node *mz_node; bool rightmost = true; 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_node, tree_node); if (mz->usage_in_excess < mz_node->usage_in_excess) { p = &(*p)->rb_left; rightmost = false; } /* * 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; } if (rightmost) mctz->rb_rightmost = &mz->tree_node; 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_per_node *mz, struct mem_cgroup_tree_per_node *mctz) { if (!mz->on_tree) return; if (&mz->tree_node == mctz->rb_rightmost) mctz->rb_rightmost = rb_prev(&mz->tree_node); rb_erase(&mz->tree_node, &mctz->rb_root); mz->on_tree = false; } static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, struct mem_cgroup_tree_per_node *mctz) { unsigned long flags; spin_lock_irqsave(&mctz->lock, flags); __mem_cgroup_remove_exceeded(mz, mctz); spin_unlock_irqrestore(&mctz->lock, flags); } static unsigned long soft_limit_excess(struct mem_cgroup *memcg) { unsigned long nr_pages = page_counter_read(&memcg->memory); unsigned long soft_limit = READ_ONCE(memcg->soft_limit); unsigned long excess = 0; if (nr_pages > soft_limit) excess = nr_pages - soft_limit; return excess; } static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page) { unsigned long excess; struct mem_cgroup_per_node *mz; struct mem_cgroup_tree_per_node *mctz; mctz = soft_limit_tree_from_page(page); if (!mctz) return; /* * 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_page_nodeinfo(memcg, page); excess = soft_limit_excess(memcg); /* * We have to update the tree if mz is on RB-tree or * mem is over its softlimit. */ if (excess || mz->on_tree) { unsigned long flags; spin_lock_irqsave(&mctz->lock, flags); /* if on-tree, remove it */ if (mz->on_tree) __mem_cgroup_remove_exceeded(mz, mctz); /* * Insert again. mz->usage_in_excess will be updated. * If excess is 0, no tree ops. */ __mem_cgroup_insert_exceeded(mz, mctz, excess); spin_unlock_irqrestore(&mctz->lock, flags); } } } static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) { struct mem_cgroup_tree_per_node *mctz; struct mem_cgroup_per_node *mz; int nid; for_each_node(nid) { mz = mem_cgroup_nodeinfo(memcg, nid); mctz = soft_limit_tree_node(nid); if (mctz) mem_cgroup_remove_exceeded(mz, mctz); } } static struct mem_cgroup_per_node * __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) { struct mem_cgroup_per_node *mz; retry: mz = NULL; if (!mctz->rb_rightmost) goto done; /* Nothing to reclaim from */ mz = rb_entry(mctz->rb_rightmost, struct mem_cgroup_per_node, 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, mctz); if (!soft_limit_excess(mz->memcg) || !css_tryget(&mz->memcg->css)) goto retry; done: return mz; } static struct mem_cgroup_per_node * mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) { struct mem_cgroup_per_node *mz; spin_lock_irq(&mctz->lock); mz = __mem_cgroup_largest_soft_limit_node(mctz); spin_unlock_irq(&mctz->lock); return mz; } /** * __mod_memcg_state - update cgroup memory statistics * @memcg: the memory cgroup * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item * @val: delta to add to the counter, can be negative */ void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val) { long x; if (mem_cgroup_disabled()) return; x = val + __this_cpu_read(memcg->vmstats_percpu->stat[idx]); if (unlikely(abs(x) > MEMCG_CHARGE_BATCH)) { struct mem_cgroup *mi; /* * Batch local counters to keep them in sync with * the hierarchical ones. */ __this_cpu_add(memcg->vmstats_local->stat[idx], x); for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) atomic_long_add(x, &mi->vmstats[idx]); x = 0; } __this_cpu_write(memcg->vmstats_percpu->stat[idx], x); } static struct mem_cgroup_per_node * parent_nodeinfo(struct mem_cgroup_per_node *pn, int nid) { struct mem_cgroup *parent; parent = parent_mem_cgroup(pn->memcg); if (!parent) return NULL; return mem_cgroup_nodeinfo(parent, nid); } /** * __mod_lruvec_state - update lruvec memory statistics * @lruvec: the lruvec * @idx: the stat item * @val: delta to add to the counter, can be negative * * The lruvec is the intersection of the NUMA node and a cgroup. This * function updates the all three counters that are affected by a * change of state at this level: per-node, per-cgroup, per-lruvec. */ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, int val) { pg_data_t *pgdat = lruvec_pgdat(lruvec); struct mem_cgroup_per_node *pn; struct mem_cgroup *memcg; long x; /* Update node */ __mod_node_page_state(pgdat, idx, val); if (mem_cgroup_disabled()) return; pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); memcg = pn->memcg; /* Update memcg */ __mod_memcg_state(memcg, idx, val); /* Update lruvec */ __this_cpu_add(pn->lruvec_stat_local->count[idx], val); x = val + __this_cpu_read(pn->lruvec_stat_cpu->count[idx]); if (unlikely(abs(x) > MEMCG_CHARGE_BATCH)) { struct mem_cgroup_per_node *pi; for (pi = pn; pi; pi = parent_nodeinfo(pi, pgdat->node_id)) atomic_long_add(x, &pi->lruvec_stat[idx]); x = 0; } __this_cpu_write(pn->lruvec_stat_cpu->count[idx], x); } void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val) { pg_data_t *pgdat = page_pgdat(virt_to_page(p)); struct mem_cgroup *memcg; struct lruvec *lruvec; rcu_read_lock(); memcg = mem_cgroup_from_obj(p); /* Untracked pages have no memcg, no lruvec. Update only the node */ if (!memcg || memcg == root_mem_cgroup) { __mod_node_page_state(pgdat, idx, val); } else { lruvec = mem_cgroup_lruvec(memcg, pgdat); __mod_lruvec_state(lruvec, idx, val); } rcu_read_unlock(); } void mod_memcg_obj_state(void *p, int idx, int val) { struct mem_cgroup *memcg; rcu_read_lock(); memcg = mem_cgroup_from_obj(p); if (memcg) mod_memcg_state(memcg, idx, val); rcu_read_unlock(); } /** * __count_memcg_events - account VM events in a cgroup * @memcg: the memory cgroup * @idx: the event item * @count: the number of events that occured */ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, unsigned long count) { unsigned long x; if (mem_cgroup_disabled()) return; x = count + __this_cpu_read(memcg->vmstats_percpu->events[idx]); if (unlikely(x > MEMCG_CHARGE_BATCH)) { struct mem_cgroup *mi; /* * Batch local counters to keep them in sync with * the hierarchical ones. */ __this_cpu_add(memcg->vmstats_local->events[idx], x); for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) atomic_long_add(x, &mi->vmevents[idx]); x = 0; } __this_cpu_write(memcg->vmstats_percpu->events[idx], x); } static unsigned long memcg_events(struct mem_cgroup *memcg, int event) { return atomic_long_read(&memcg->vmevents[event]); } static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event) { long x = 0; int cpu; for_each_possible_cpu(cpu) x += per_cpu(memcg->vmstats_local->events[event], cpu); return x; } static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, struct page *page, bool compound, int nr_pages) { /* * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is * counted as CACHE even if it's on ANON LRU. */ if (PageAnon(page)) __mod_memcg_state(memcg, MEMCG_RSS, nr_pages); else { __mod_memcg_state(memcg, MEMCG_CACHE, nr_pages); if (PageSwapBacked(page)) __mod_memcg_state(memcg, NR_SHMEM, nr_pages); } if (compound) { VM_BUG_ON_PAGE(!PageTransHuge(page), page); __mod_memcg_state(memcg, MEMCG_RSS_HUGE, nr_pages); } /* pagein of a big page is an event. So, ignore page size */ if (nr_pages > 0) __count_memcg_events(memcg, PGPGIN, 1); else { __count_memcg_events(memcg, PGPGOUT, 1); nr_pages = -nr_pages; /* for event */ } __this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages); } 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->vmstats_percpu->nr_page_events); next = __this_cpu_read(memcg->vmstats_percpu->targets[target]); /* from time_after() in jiffies.h */ if ((long)(next - 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; default: break; } __this_cpu_write(memcg->vmstats_percpu->targets[target], next); return true; } return false; } /* * Check events in order. * */ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) { /* threshold event is triggered in finer grain than soft limit */ if (unlikely(mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_THRESH))) { bool do_softlimit; do_softlimit = mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_SOFTLIMIT); mem_cgroup_threshold(memcg); if (unlikely(do_softlimit)) mem_cgroup_update_tree(memcg, page); } } 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, memory_cgrp_id)); } EXPORT_SYMBOL(mem_cgroup_from_task); /** * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg. * @mm: mm from which memcg should be extracted. It can be NULL. * * Obtain a reference on mm->memcg and returns it if successful. Otherwise * root_mem_cgroup is returned. However if mem_cgroup is disabled, NULL is * returned. */ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) { struct mem_cgroup *memcg; if (mem_cgroup_disabled()) return NULL; rcu_read_lock(); do { /* * Page cache insertions can happen withou an * actual mm context, e.g. during disk probing * on boot, loopback IO, acct() writes etc. */ if (unlikely(!mm)) memcg = root_mem_cgroup; else { memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); if (unlikely(!memcg)) memcg = root_mem_cgroup; } } while (!css_tryget(&memcg->css)); rcu_read_unlock(); return memcg; } EXPORT_SYMBOL(get_mem_cgroup_from_mm); /** * get_mem_cgroup_from_page: Obtain a reference on given page's memcg. * @page: page from which memcg should be extracted. * * Obtain a reference on page->memcg and returns it if successful. Otherwise * root_mem_cgroup is returned. */ struct mem_cgroup *get_mem_cgroup_from_page(struct page *page) { struct mem_cgroup *memcg = page->mem_cgroup; if (mem_cgroup_disabled()) return NULL; rcu_read_lock(); /* Page should not get uncharged and freed memcg under us. */ if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css))) memcg = root_mem_cgroup; rcu_read_unlock(); return memcg; } EXPORT_SYMBOL(get_mem_cgroup_from_page); /** * If current->active_memcg is non-NULL, do not fallback to current->mm->memcg. */ static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void) { if (unlikely(current->active_memcg)) { struct mem_cgroup *memcg; rcu_read_lock(); /* current->active_memcg must hold a ref. */ if (WARN_ON_ONCE(!css_tryget(¤t->active_memcg->css))) memcg = root_mem_cgroup; else memcg = current->active_memcg; rcu_read_unlock(); return memcg; } return get_mem_cgroup_from_mm(current->mm); } /** * 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 node and a priority level in @reclaim to * divide up the memcgs in the hierarchy among all concurrent * reclaimers operating on the same node 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_reclaim_iter *uninitialized_var(iter); struct cgroup_subsys_state *css = NULL; struct mem_cgroup *memcg = NULL; struct mem_cgroup *pos = NULL; if (mem_cgroup_disabled()) return NULL; if (!root) root = root_mem_cgroup; if (prev && !reclaim) pos = prev; if (!root->use_hierarchy && root != root_mem_cgroup) { if (prev) goto out; return root; } rcu_read_lock(); if (reclaim) { struct mem_cgroup_per_node *mz; mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id); iter = &mz->iter; if (prev && reclaim->generation != iter->generation) goto out_unlock; while (1) { pos = READ_ONCE(iter->position); if (!pos || css_tryget(&pos->css)) break; /* * css reference reached zero, so iter->position will * be cleared by ->css_released. However, we should not * rely on this happening soon, because ->css_released * is called from a work queue, and by busy-waiting we * might block it. So we clear iter->position right * away. */ (void)cmpxchg(&iter->position, pos, NULL); } } if (pos) css = &pos->css; for (;;) { css = css_next_descendant_pre(css, &root->css); if (!css) { /* * Reclaimers share the hierarchy walk, and a * new one might jump in right at the end of * the hierarchy - make sure they see at least * one group and restart from the beginning. */ if (!prev) continue; break; } /* * Verify the css and acquire a reference. The root * is provided by the caller, so we know it's alive * and kicking, and don't take an extra reference. */ memcg = mem_cgroup_from_css(css); if (css == &root->css) break; if (css_tryget(css)) break; memcg = NULL; } if (reclaim) { /* * The position could have already been updated by a competing * thread, so check that the value hasn't changed since we read * it to avoid reclaiming from the same cgroup twice. */ (void)cmpxchg(&iter->position, pos, memcg); if (pos) css_put(&pos->css); if (!memcg) iter->generation++; else if (!prev) reclaim->generation = iter->generation; } out_unlock: rcu_read_unlock(); out: 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); } static void __invalidate_reclaim_iterators(struct mem_cgroup *from, struct mem_cgroup *dead_memcg) { struct mem_cgroup_reclaim_iter *iter; struct mem_cgroup_per_node *mz; int nid; for_each_node(nid) { mz = mem_cgroup_nodeinfo(from, nid); iter = &mz->iter; cmpxchg(&iter->position, dead_memcg, NULL); } } static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) { struct mem_cgroup *memcg = dead_memcg; struct mem_cgroup *last; do { __invalidate_reclaim_iterators(memcg, dead_memcg); last = memcg; } while ((memcg = parent_mem_cgroup(memcg))); /* * When cgruop1 non-hierarchy mode is used, * parent_mem_cgroup() does not walk all the way up to the * cgroup root (root_mem_cgroup). So we have to handle * dead_memcg from cgroup root separately. */ if (last != root_mem_cgroup) __invalidate_reclaim_iterators(root_mem_cgroup, dead_memcg); } /** * mem_cgroup_scan_tasks - iterate over tasks of a memory cgroup hierarchy * @memcg: hierarchy root * @fn: function to call for each task * @arg: argument passed to @fn * * This function iterates over tasks attached to @memcg or to any of its * descendants and calls @fn for each task. If @fn returns a non-zero * value, the function breaks the iteration loop and returns the value. * Otherwise, it will iterate over all tasks and return 0. * * This function must not be called for the root memory cgroup. */ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg, int (*fn)(struct task_struct *, void *), void *arg) { struct mem_cgroup *iter; int ret = 0; BUG_ON(memcg == root_mem_cgroup); for_each_mem_cgroup_tree(iter, memcg) { struct css_task_iter it; struct task_struct *task; css_task_iter_start(&iter->css, CSS_TASK_ITER_PROCS, &it); while (!ret && (task = css_task_iter_next(&it))) ret = fn(task, arg); css_task_iter_end(&it); if (ret) { mem_cgroup_iter_break(memcg, iter); break; } } return ret; } /** * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page * @page: the page * @pgdat: pgdat of the page * * This function is only safe when following the LRU page isolation * and putback protocol: the LRU lock must be held, and the page must * either be PageLRU() or the caller must have isolated/allocated it. */ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat) { struct mem_cgroup_per_node *mz; struct mem_cgroup *memcg; struct lruvec *lruvec; if (mem_cgroup_disabled()) { lruvec = &pgdat->__lruvec; goto out; } memcg = page->mem_cgroup; /* * Swapcache readahead pages are added to the LRU - and * possibly migrated - before they are charged. */ if (!memcg) memcg = root_mem_cgroup; mz = mem_cgroup_page_nodeinfo(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->pgdat != pgdat)) lruvec->pgdat = pgdat; 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 * @zid: zone id of the accounted pages * @nr_pages: positive when adding or negative when removing * * This function must be called under lru_lock, just before a page is added * to or just after a page is removed from an lru list (that ordering being * so as to allow it to check that lru_size 0 is consistent with list_empty). */ void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, int zid, int nr_pages) { struct mem_cgroup_per_node *mz; unsigned long *lru_size; long size; if (mem_cgroup_disabled()) return; mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec); lru_size = &mz->lru_zone_size[zid][lru]; if (nr_pages < 0) *lru_size += nr_pages; size = *lru_size; if (WARN_ONCE(size < 0, "%s(%p, %d, %d): lru_size %ld\n", __func__, lruvec, lru, nr_pages, size)) { VM_BUG_ON(1); *lru_size = 0; } if (nr_pages > 0) *lru_size += nr_pages; } /** * 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 margin = 0; unsigned long count; unsigned long limit; count = page_counter_read(&memcg->memory); limit = READ_ONCE(memcg->memory.max); if (count < limit) margin = limit - count; if (do_memsw_account()) { count = page_counter_read(&memcg->memsw); limit = READ_ONCE(memcg->memsw.max); if (count < limit) margin = min(margin, limit - count); else margin = 0; } return margin; } /* * A routine for checking "mem" is under move_account() or not. * * Checking a cgroup is mc.from or mc.to or under hierarchy of * moving cgroups. This is for waiting at high-memory pressure * caused by "move". */ 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_is_descendant(from, memcg) || mem_cgroup_is_descendant(to, memcg); 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; } static char *memory_stat_format(struct mem_cgroup *memcg) { struct seq_buf s; int i; seq_buf_init(&s, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE); if (!s.buffer) return NULL; /* * Provide statistics on the state of the memory subsystem as * well as cumulative event counters that show past behavior. * * This list is ordered following a combination of these gradients: * 1) generic big picture -> specifics and details * 2) reflecting userspace activity -> reflecting kernel heuristics * * Current memory state: */ seq_buf_printf(&s, "anon %llu\n", (u64)memcg_page_state(memcg, MEMCG_RSS) * PAGE_SIZE); seq_buf_printf(&s, "file %llu\n", (u64)memcg_page_state(memcg, MEMCG_CACHE) * PAGE_SIZE); seq_buf_printf(&s, "kernel_stack %llu\n", (u64)memcg_page_state(memcg, MEMCG_KERNEL_STACK_KB) * 1024); seq_buf_printf(&s, "slab %llu\n", (u64)(memcg_page_state(memcg, NR_SLAB_RECLAIMABLE) + memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE)) * PAGE_SIZE); seq_buf_printf(&s, "sock %llu\n", (u64)memcg_page_state(memcg, MEMCG_SOCK) * PAGE_SIZE); seq_buf_printf(&s, "shmem %llu\n", (u64)memcg_page_state(memcg, NR_SHMEM) * PAGE_SIZE); seq_buf_printf(&s, "file_mapped %llu\n", (u64)memcg_page_state(memcg, NR_FILE_MAPPED) * PAGE_SIZE); seq_buf_printf(&s, "file_dirty %llu\n", (u64)memcg_page_state(memcg, NR_FILE_DIRTY) * PAGE_SIZE); seq_buf_printf(&s, "file_writeback %llu\n", (u64)memcg_page_state(memcg, NR_WRITEBACK) * PAGE_SIZE); /* * TODO: We should eventually replace our own MEMCG_RSS_HUGE counter * with the NR_ANON_THP vm counter, but right now it's a pain in the * arse because it requires migrating the work out of rmap to a place * where the page->mem_cgroup is set up and stable. */ seq_buf_printf(&s, "anon_thp %llu\n", (u64)memcg_page_state(memcg, MEMCG_RSS_HUGE) * PAGE_SIZE); for (i = 0; i < NR_LRU_LISTS; i++) seq_buf_printf(&s, "%s %llu\n", lru_list_name(i), (u64)memcg_page_state(memcg, NR_LRU_BASE + i) * PAGE_SIZE); seq_buf_printf(&s, "slab_reclaimable %llu\n", (u64)memcg_page_state(memcg, NR_SLAB_RECLAIMABLE) * PAGE_SIZE); seq_buf_printf(&s, "slab_unreclaimable %llu\n", (u64)memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE) * PAGE_SIZE); /* Accumulated memory events */ seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGFAULT), memcg_events(memcg, PGFAULT)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGMAJFAULT), memcg_events(memcg, PGMAJFAULT)); seq_buf_printf(&s, "workingset_refault %lu\n", memcg_page_state(memcg, WORKINGSET_REFAULT)); seq_buf_printf(&s, "workingset_activate %lu\n", memcg_page_state(memcg, WORKINGSET_ACTIVATE)); seq_buf_printf(&s, "workingset_restore %lu\n", memcg_page_state(memcg, WORKINGSET_RESTORE)); seq_buf_printf(&s, "workingset_nodereclaim %lu\n", memcg_page_state(memcg, WORKINGSET_NODERECLAIM)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGREFILL), memcg_events(memcg, PGREFILL)); seq_buf_printf(&s, "pgscan %lu\n", memcg_events(memcg, PGSCAN_KSWAPD) + memcg_events(memcg, PGSCAN_DIRECT)); seq_buf_printf(&s, "pgsteal %lu\n", memcg_events(memcg, PGSTEAL_KSWAPD) + memcg_events(memcg, PGSTEAL_DIRECT)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGACTIVATE), memcg_events(memcg, PGACTIVATE)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGDEACTIVATE), memcg_events(memcg, PGDEACTIVATE)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREE), memcg_events(memcg, PGLAZYFREE)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREED), memcg_events(memcg, PGLAZYFREED)); #ifdef CONFIG_TRANSPARENT_HUGEPAGE seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_FAULT_ALLOC), memcg_events(memcg, THP_FAULT_ALLOC)); seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_COLLAPSE_ALLOC), memcg_events(memcg, THP_COLLAPSE_ALLOC)); #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ /* The above should easily fit into one page */ WARN_ON_ONCE(seq_buf_has_overflowed(&s)); return s.buffer; } #define K(x) ((x) << (PAGE_SHIFT-10)) /** * mem_cgroup_print_oom_context: 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_context(struct mem_cgroup *memcg, struct task_struct *p) { rcu_read_lock(); if (memcg) { pr_cont(",oom_memcg="); pr_cont_cgroup_path(memcg->css.cgroup); } else pr_cont(",global_oom"); if (p) { pr_cont(",task_memcg="); pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id)); } rcu_read_unlock(); } /** * mem_cgroup_print_oom_meminfo: Print OOM memory information relevant to * memory controller. * @memcg: The memory cgroup that went over limit */ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) { char *buf; pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->memory)), K((u64)READ_ONCE(memcg->memory.max)), memcg->memory.failcnt); if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->swap)), K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt); else { pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->memsw)), K((u64)memcg->memsw.max), memcg->memsw.failcnt); pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->kmem)), K((u64)memcg->kmem.max), memcg->kmem.failcnt); } pr_info("Memory cgroup stats for "); pr_cont_cgroup_path(memcg->css.cgroup); pr_cont(":"); buf = memory_stat_format(memcg); if (!buf) return; pr_info("%s", buf); kfree(buf); } /* * Return the memory (and swap, if configured) limit for a memcg. */ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) { unsigned long max; max = READ_ONCE(memcg->memory.max); if (mem_cgroup_swappiness(memcg)) { unsigned long memsw_max; unsigned long swap_max; memsw_max = memcg->memsw.max; swap_max = READ_ONCE(memcg->swap.max); swap_max = min(swap_max, (unsigned long)total_swap_pages); max = min(max + swap_max, memsw_max); } return max; } unsigned long mem_cgroup_size(struct mem_cgroup *memcg) { return page_counter_read(&memcg->memory); } static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, int order) { struct oom_control oc = { .zonelist = NULL, .nodemask = NULL, .memcg = memcg, .gfp_mask = gfp_mask, .order = order, }; bool ret; if (mutex_lock_killable(&oom_lock)) return true; /* * A few threads which were not waiting at mutex_lock_killable() can * fail to bail out. Therefore, check again after holding oom_lock. */ ret = should_force_charge() || out_of_memory(&oc); mutex_unlock(&oom_lock); return ret; } static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, pg_data_t *pgdat, 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 = { .pgdat = pgdat, }; excess = soft_limit_excess(root_memcg); 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; } total += mem_cgroup_shrink_node(victim, gfp_mask, false, pgdat, &nr_scanned); *total_scanned += nr_scanned; if (!soft_limit_excess(root_memcg)) break; } mem_cgroup_iter_break(root_memcg, victim); return total; } #ifdef CONFIG_LOCKDEP static struct lockdep_map memcg_oom_lock_dep_map = { .name = "memcg_oom_lock", }; #endif 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; } } else mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_); 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); mutex_release(&memcg_oom_lock_dep_map, _RET_IP_); 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; spin_lock(&memcg_oom_lock); for_each_mem_cgroup_tree(iter, memcg) iter->under_oom++; spin_unlock(&memcg_oom_lock); } 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. Watch for underflow. */ spin_lock(&memcg_oom_lock); for_each_mem_cgroup_tree(iter, memcg) if (iter->under_oom > 0) iter->under_oom--; spin_unlock(&memcg_oom_lock); } static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); struct oom_wait_info { struct mem_cgroup *memcg; wait_queue_entry_t wait; }; static int memcg_oom_wake_function(wait_queue_entry_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; if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) && !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg)) return 0; return autoremove_wake_function(wait, mode, sync, arg); } static void memcg_oom_recover(struct mem_cgroup *memcg) { /* * For the following lockless ->under_oom test, the only required * guarantee is that it must see the state asserted by an OOM when * this function is called as a result of userland actions * triggered by the notification of the OOM. This is trivially * achieved by invoking mem_cgroup_mark_under_oom() before * triggering notification. */ if (memcg && memcg->under_oom) __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); } enum oom_status { OOM_SUCCESS, OOM_FAILED, OOM_ASYNC, OOM_SKIPPED }; static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) { enum oom_status ret; bool locked; if (order > PAGE_ALLOC_COSTLY_ORDER) return OOM_SKIPPED; memcg_memory_event(memcg, MEMCG_OOM); /* * We are in the middle of the charge context here, so we * don't want to block when potentially sitting on a callstack * that holds all kinds of filesystem and mm locks. * * cgroup1 allows disabling the OOM killer and waiting for outside * handling until the charge can succeed; remember the context and put * the task to sleep at the end of the page fault when all locks are * released. * * On the other hand, in-kernel OOM killer allows for an async victim * memory reclaim (oom_reaper) and that means that we are not solely * relying on the oom victim to make a forward progress and we can * invoke the oom killer here. * * Please note that mem_cgroup_out_of_memory might fail to find a * victim and then we have to bail out from the charge path. */ if (memcg->oom_kill_disable) { if (!current->in_user_fault) return OOM_SKIPPED; css_get(&memcg->css); current->memcg_in_oom = memcg; current->memcg_oom_gfp_mask = mask; current->memcg_oom_order = order; return OOM_ASYNC; } mem_cgroup_mark_under_oom(memcg); locked = mem_cgroup_oom_trylock(memcg); if (locked) mem_cgroup_oom_notify(memcg); mem_cgroup_unmark_under_oom(memcg); if (mem_cgroup_out_of_memory(memcg, mask, order)) ret = OOM_SUCCESS; else ret = OOM_FAILED; if (locked) mem_cgroup_oom_unlock(memcg); return ret; } /** * mem_cgroup_oom_synchronize - complete memcg OOM handling * @handle: actually kill/wait or just clean up the OOM state * * This has to be called at the end of a page fault if the memcg OOM * handler was enabled. * * Memcg supports userspace OOM handling where 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 complete the OOM handling. * * Returns %true if an ongoing memcg OOM situation was detected and * completed, %false otherwise. */ bool mem_cgroup_oom_synchronize(bool handle) { struct mem_cgroup *memcg = current->memcg_in_oom; struct oom_wait_info owait; bool locked; /* OOM is global, do not handle */ if (!memcg) return false; if (!handle) goto cleanup; owait.memcg = memcg; owait.wait.flags = 0; owait.wait.func = memcg_oom_wake_function; owait.wait.private = current; INIT_LIST_HEAD(&owait.wait.entry); prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); 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); finish_wait(&memcg_oom_waitq, &owait.wait); mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask, current->memcg_oom_order); } else { schedule(); mem_cgroup_unmark_under_oom(memcg); finish_wait(&memcg_oom_waitq, &owait.wait); } if (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); } cleanup: current->memcg_in_oom = NULL; css_put(&memcg->css); return true; } /** * mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM * @victim: task to be killed by the OOM killer * @oom_domain: memcg in case of memcg OOM, NULL in case of system-wide OOM * * Returns a pointer to a memory cgroup, which has to be cleaned up * by killing all belonging OOM-killable tasks. * * Caller has to call mem_cgroup_put() on the returned non-NULL memcg. */ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim, struct mem_cgroup *oom_domain) { struct mem_cgroup *oom_group = NULL; struct mem_cgroup *memcg; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return NULL; if (!oom_domain) oom_domain = root_mem_cgroup; rcu_read_lock(); memcg = mem_cgroup_from_task(victim); if (memcg == root_mem_cgroup) goto out; /* * If the victim task has been asynchronously moved to a different * memory cgroup, we might end up killing tasks outside oom_domain. * In this case it's better to ignore memory.group.oom. */ if (unlikely(!mem_cgroup_is_descendant(memcg, oom_domain))) goto out; /* * Traverse the memory cgroup hierarchy from the victim task's * cgroup up to the OOMing cgroup (or root) to find the * highest-level memory cgroup with oom.group set. */ for (; memcg; memcg = parent_mem_cgroup(memcg)) { if (memcg->oom_group) oom_group = memcg; if (memcg == oom_domain) break; } if (oom_group) css_get(&oom_group->css); out: rcu_read_unlock(); return oom_group; } void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) { pr_info("Tasks in "); pr_cont_cgroup_path(memcg->css.cgroup); pr_cont(" are going to be killed due to memory.oom.group set\n"); } /** * lock_page_memcg - lock a page->mem_cgroup binding * @page: the page * * This function protects unlocked LRU pages from being moved to * another cgroup. * * It ensures lifetime of the returned memcg. Caller is responsible * for the lifetime of the page; __unlock_page_memcg() is available * when @page might get freed inside the locked section. */ struct mem_cgroup *lock_page_memcg(struct page *page) { struct mem_cgroup *memcg; unsigned long flags; /* * The RCU lock is held throughout the transaction. The fast * path can get away without acquiring the memcg->move_lock * because page moving starts with an RCU grace period. * * The RCU lock also protects the memcg from being freed when * the page state that is going to change is the only thing * preventing the page itself from being freed. E.g. writeback * doesn't hold a page reference and relies on PG_writeback to * keep off truncation, migration and so forth. */ rcu_read_lock(); if (mem_cgroup_disabled()) return NULL; again: memcg = page->mem_cgroup; if (unlikely(!memcg)) return NULL; if (atomic_read(&memcg->moving_account) <= 0) return memcg; spin_lock_irqsave(&memcg->move_lock, flags); if (memcg != page->mem_cgroup) { spin_unlock_irqrestore(&memcg->move_lock, flags); goto again; } /* * When charge migration first begins, we can have locked and * unlocked page stat updates happening concurrently. Track * the task who has the lock for unlock_page_memcg(). */ memcg->move_lock_task = current; memcg->move_lock_flags = flags; return memcg; } EXPORT_SYMBOL(lock_page_memcg); /** * __unlock_page_memcg - unlock and unpin a memcg * @memcg: the memcg * * Unlock and unpin a memcg returned by lock_page_memcg(). */ void __unlock_page_memcg(struct mem_cgroup *memcg) { if (memcg && memcg->move_lock_task == current) { unsigned long flags = memcg->move_lock_flags; memcg->move_lock_task = NULL; memcg->move_lock_flags = 0; spin_unlock_irqrestore(&memcg->move_lock, flags); } rcu_read_unlock(); } /** * unlock_page_memcg - unlock a page->mem_cgroup binding * @page: the page */ void unlock_page_memcg(struct page *page) { __unlock_page_memcg(page->mem_cgroup); } EXPORT_SYMBOL(unlock_page_memcg); 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; unsigned long flags; bool ret = false; if (nr_pages > MEMCG_CHARGE_BATCH) return ret; local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) { stock->nr_pages -= nr_pages; ret = true; } local_irq_restore(flags); return ret; } /* * Returns stocks cached in percpu and reset cached information. */ static void drain_stock(struct memcg_stock_pcp *stock) { struct mem_cgroup *old = stock->cached; if (stock->nr_pages) { page_counter_uncharge(&old->memory, stock->nr_pages); if (do_memsw_account()) page_counter_uncharge(&old->memsw, stock->nr_pages); css_put_many(&old->css, stock->nr_pages); stock->nr_pages = 0; } stock->cached = NULL; } static void drain_local_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock; unsigned long flags; /* * The only protection from memory hotplug vs. drain_stock races is * that we always operate on local CPU stock here with IRQ disabled */ local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); local_irq_restore(flags); } /* * Cache charges(val) 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; unsigned long flags; local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); stock->cached = memcg; } stock->nr_pages += nr_pages; if (stock->nr_pages > MEMCG_CHARGE_BATCH) drain_stock(stock); local_irq_restore(flags); } /* * Drains all per-CPU charge caches for given root_memcg resp. subtree * of the hierarchy under it. */ static void drain_all_stock(struct mem_cgroup *root_memcg) { int cpu, curcpu; /* If someone's already draining, avoid adding running more workers. */ if (!mutex_trylock(&percpu_charge_mutex)) return; /* * Notify other cpus that system-wide "drain" is running * We do not care about races with the cpu hotplug because cpu down * as well as workers from this path always operate on the local * per-cpu data. CPU up doesn't touch memcg_stock at all. */ curcpu = get_cpu(); for_each_online_cpu(cpu) { struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); struct mem_cgroup *memcg; bool flush = false; rcu_read_lock(); memcg = stock->cached; if (memcg && stock->nr_pages && mem_cgroup_is_descendant(memcg, root_memcg)) flush = true; rcu_read_unlock(); if (flush && !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(); mutex_unlock(&percpu_charge_mutex); } static int memcg_hotplug_cpu_dead(unsigned int cpu) { struct memcg_stock_pcp *stock; struct mem_cgroup *memcg, *mi; stock = &per_cpu(memcg_stock, cpu); drain_stock(stock); for_each_mem_cgroup(memcg) { int i; for (i = 0; i < MEMCG_NR_STAT; i++) { int nid; long x; x = this_cpu_xchg(memcg->vmstats_percpu->stat[i], 0); if (x) for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) atomic_long_add(x, &memcg->vmstats[i]); if (i >= NR_VM_NODE_STAT_ITEMS) continue; for_each_node(nid) { struct mem_cgroup_per_node *pn; pn = mem_cgroup_nodeinfo(memcg, nid); x = this_cpu_xchg(pn->lruvec_stat_cpu->count[i], 0); if (x) do { atomic_long_add(x, &pn->lruvec_stat[i]); } while ((pn = parent_nodeinfo(pn, nid))); } } for (i = 0; i < NR_VM_EVENT_ITEMS; i++) { long x; x = this_cpu_xchg(memcg->vmstats_percpu->events[i], 0); if (x) for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) atomic_long_add(x, &memcg->vmevents[i]); } } return 0; } static void reclaim_high(struct mem_cgroup *memcg, unsigned int nr_pages, gfp_t gfp_mask) { do { if (page_counter_read(&memcg->memory) <= READ_ONCE(memcg->memory.high)) continue; memcg_memory_event(memcg, MEMCG_HIGH); try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); } while ((memcg = parent_mem_cgroup(memcg)) && !mem_cgroup_is_root(memcg)); } static void high_work_func(struct work_struct *work) { struct mem_cgroup *memcg; memcg = container_of(work, struct mem_cgroup, high_work); reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL); } /* * Clamp the maximum sleep time per allocation batch to 2 seconds. This is * enough to still cause a significant slowdown in most cases, while still * allowing diagnostics and tracing to proceed without becoming stuck. */ #define MEMCG_MAX_HIGH_DELAY_JIFFIES (2UL*HZ) /* * When calculating the delay, we use these either side of the exponentiation to * maintain precision and scale to a reasonable number of jiffies (see the table * below. * * - MEMCG_DELAY_PRECISION_SHIFT: Extra precision bits while translating the * overage ratio to a delay. * - MEMCG_DELAY_SCALING_SHIFT: The number of bits to scale down down the * proposed penalty in order to reduce to a reasonable number of jiffies, and * to produce a reasonable delay curve. * * MEMCG_DELAY_SCALING_SHIFT just happens to be a number that produces a * reasonable delay curve compared to precision-adjusted overage, not * penalising heavily at first, but still making sure that growth beyond the * limit penalises misbehaviour cgroups by slowing them down exponentially. For * example, with a high of 100 megabytes: * * +-------+------------------------+ * | usage | time to allocate in ms | * +-------+------------------------+ * | 100M | 0 | * | 101M | 6 | * | 102M | 25 | * | 103M | 57 | * | 104M | 102 | * | 105M | 159 | * | 106M | 230 | * | 107M | 313 | * | 108M | 409 | * | 109M | 518 | * | 110M | 639 | * | 111M | 774 | * | 112M | 921 | * | 113M | 1081 | * | 114M | 1254 | * | 115M | 1439 | * | 116M | 1638 | * | 117M | 1849 | * | 118M | 2000 | * | 119M | 2000 | * | 120M | 2000 | * +-------+------------------------+ */ #define MEMCG_DELAY_PRECISION_SHIFT 20 #define MEMCG_DELAY_SCALING_SHIFT 14 static u64 calculate_overage(unsigned long usage, unsigned long high) { u64 overage; if (usage <= high) return 0; /* * Prevent division by 0 in overage calculation by acting as if * it was a threshold of 1 page */ high = max(high, 1UL); overage = usage - high; overage <<= MEMCG_DELAY_PRECISION_SHIFT; return div64_u64(overage, high); } static u64 mem_find_max_overage(struct mem_cgroup *memcg) { u64 overage, max_overage = 0; do { overage = calculate_overage(page_counter_read(&memcg->memory), READ_ONCE(memcg->memory.high)); max_overage = max(overage, max_overage); } while ((memcg = parent_mem_cgroup(memcg)) && !mem_cgroup_is_root(memcg)); return max_overage; } static u64 swap_find_max_overage(struct mem_cgroup *memcg) { u64 overage, max_overage = 0; do { overage = calculate_overage(page_counter_read(&memcg->swap), READ_ONCE(memcg->swap.high)); if (overage) memcg_memory_event(memcg, MEMCG_SWAP_HIGH); max_overage = max(overage, max_overage); } while ((memcg = parent_mem_cgroup(memcg)) && !mem_cgroup_is_root(memcg)); return max_overage; } /* * Get the number of jiffies that we should penalise a mischievous cgroup which * is exceeding its memory.high by checking both it and its ancestors. */ static unsigned long calculate_high_delay(struct mem_cgroup *memcg, unsigned int nr_pages, u64 max_overage) { unsigned long penalty_jiffies; if (!max_overage) return 0; /* * We use overage compared to memory.high to calculate the number of * jiffies to sleep (penalty_jiffies). Ideally this value should be * fairly lenient on small overages, and increasingly harsh when the * memcg in question makes it clear that it has no intention of stopping * its crazy behaviour, so we exponentially increase the delay based on * overage amount. */ penalty_jiffies = max_overage * max_overage * HZ; penalty_jiffies >>= MEMCG_DELAY_PRECISION_SHIFT; penalty_jiffies >>= MEMCG_DELAY_SCALING_SHIFT; /* * Factor in the task's own contribution to the overage, such that four * N-sized allocations are throttled approximately the same as one * 4N-sized allocation. * * MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or * larger the current charge patch is than that. */ return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH; } /* * Scheduled by try_charge() to be executed from the userland return path * and reclaims memory over the high limit. */ void mem_cgroup_handle_over_high(void) { unsigned long penalty_jiffies; unsigned long pflags; unsigned int nr_pages = current->memcg_nr_pages_over_high; struct mem_cgroup *memcg; if (likely(!nr_pages)) return; memcg = get_mem_cgroup_from_mm(current->mm); reclaim_high(memcg, nr_pages, GFP_KERNEL); current->memcg_nr_pages_over_high = 0; /* * memory.high is breached and reclaim is unable to keep up. Throttle * allocators proactively to slow down excessive growth. */ penalty_jiffies = calculate_high_delay(memcg, nr_pages, mem_find_max_overage(memcg)); penalty_jiffies += calculate_high_delay(memcg, nr_pages, swap_find_max_overage(memcg)); /* * Clamp the max delay per usermode return so as to still keep the * application moving forwards and also permit diagnostics, albeit * extremely slowly. */ penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES); /* * Don't sleep if the amount of jiffies this memcg owes us is so low * that it's not even worth doing, in an attempt to be nice to those who * go only a small amount over their memory.high value and maybe haven't * been aggressively reclaimed enough yet. */ if (penalty_jiffies <= HZ / 100) goto out; /* * If we exit early, we're guaranteed to die (since * schedule_timeout_killable sets TASK_KILLABLE). This means we don't * need to account for any ill-begotten jiffies to pay them off later. */ psi_memstall_enter(&pflags); schedule_timeout_killable(penalty_jiffies); psi_memstall_leave(&pflags); out: css_put(&memcg->css); } static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages) { unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; struct mem_cgroup *mem_over_limit; struct page_counter *counter; unsigned long nr_reclaimed; bool may_swap = true; bool drained = false; enum oom_status oom_status; if (mem_cgroup_is_root(memcg)) return 0; retry: if (consume_stock(memcg, nr_pages)) return 0; if (!do_memsw_account() || page_counter_try_charge(&memcg->memsw, batch, &counter)) { if (page_counter_try_charge(&memcg->memory, batch, &counter)) goto done_restock; if (do_memsw_account()) page_counter_uncharge(&memcg->memsw, batch); mem_over_limit = mem_cgroup_from_counter(counter, memory); } else { mem_over_limit = mem_cgroup_from_counter(counter, memsw); may_swap = false; } if (batch > nr_pages) { batch = nr_pages; goto retry; } /* * Memcg doesn't have a dedicated reserve for atomic * allocations. But like the global atomic pool, we need to * put the burden of reclaim on regular allocation requests * and let these go through as privileged allocations. */ if (gfp_mask & __GFP_ATOMIC) goto force; /* * Unlike in global OOM situations, memcg is not in a physical * memory shortage. Allow dying and OOM-killed tasks to * bypass the last charges so that they can exit quickly and * free their memory. */ if (unlikely(should_force_charge())) goto force; /* * Prevent unbounded recursion when reclaim operations need to * allocate memory. This might exceed the limits temporarily, * but we prefer facilitating memory reclaim and getting back * under the limit over triggering OOM kills in these cases. */ if (unlikely(current->flags & PF_MEMALLOC)) goto force; if (unlikely(task_in_memcg_oom(current))) goto nomem; if (!gfpflags_allow_blocking(gfp_mask)) goto nomem; memcg_memory_event(mem_over_limit, MEMCG_MAX); nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, gfp_mask, may_swap); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) goto retry; if (!drained) { drain_all_stock(mem_over_limit); drained = true; goto retry; } if (gfp_mask & __GFP_NORETRY) goto nomem; /* * 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_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER)) goto 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)) goto retry; if (nr_retries--) goto retry; if (gfp_mask & __GFP_RETRY_MAYFAIL) goto nomem; if (gfp_mask & __GFP_NOFAIL) goto force; if (fatal_signal_pending(current)) goto force; /* * keep retrying as long as the memcg oom killer is able to make * a forward progress or bypass the charge if the oom killer * couldn't make any progress. */ oom_status = mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(nr_pages * PAGE_SIZE)); switch (oom_status) { case OOM_SUCCESS: nr_retries = MEM_CGROUP_RECLAIM_RETRIES; goto retry; case OOM_FAILED: goto force; default: goto nomem; } nomem: if (!(gfp_mask & __GFP_NOFAIL)) return -ENOMEM; force: /* * The allocation either can't fail or will lead to more memory * being freed very soon. Allow memory usage go over the limit * temporarily by force charging it. */ page_counter_charge(&memcg->memory, nr_pages); if (do_memsw_account()) page_counter_charge(&memcg->memsw, nr_pages); css_get_many(&memcg->css, nr_pages); return 0; done_restock: css_get_many(&memcg->css, batch); if (batch > nr_pages) refill_stock(memcg, batch - nr_pages); /* * If the hierarchy is above the normal consumption range, schedule * reclaim on returning to userland. We can perform reclaim here * if __GFP_RECLAIM but let's always punt for simplicity and so that * GFP_KERNEL can consistently be used during reclaim. @memcg is * not recorded as it most likely matches current's and won't * change in the meantime. As high limit is checked again before * reclaim, the cost of mismatch is negligible. */ do { bool mem_high, swap_high; mem_high = page_counter_read(&memcg->memory) > READ_ONCE(memcg->memory.high); swap_high = page_counter_read(&memcg->swap) > READ_ONCE(memcg->swap.high); /* Don't bother a random interrupted task */ if (in_interrupt()) { if (mem_high) { schedule_work(&memcg->high_work); break; } continue; } if (mem_high || swap_high) { /* * The allocating tasks in this cgroup will need to do * reclaim or be throttled to prevent further growth * of the memory or swap footprints. * * Target some best-effort fairness between the tasks, * and distribute reclaim work and delay penalties * based on how much each task is actually allocating. */ current->memcg_nr_pages_over_high += batch; set_notify_resume(current); break; } } while ((memcg = parent_mem_cgroup(memcg))); return 0; } static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) { if (mem_cgroup_is_root(memcg)) return; page_counter_uncharge(&memcg->memory, nr_pages); if (do_memsw_account()) page_counter_uncharge(&memcg->memsw, nr_pages); css_put_many(&memcg->css, nr_pages); } static void lock_page_lru(struct page *page, int *isolated) { pg_data_t *pgdat = page_pgdat(page); spin_lock_irq(&pgdat->lru_lock); if (PageLRU(page)) { struct lruvec *lruvec; lruvec = mem_cgroup_page_lruvec(page, pgdat); ClearPageLRU(page); del_page_from_lru_list(page, lruvec, page_lru(page)); *isolated = 1; } else *isolated = 0; } static void unlock_page_lru(struct page *page, int isolated) { pg_data_t *pgdat = page_pgdat(page); if (isolated) { struct lruvec *lruvec; lruvec = mem_cgroup_page_lruvec(page, pgdat); VM_BUG_ON_PAGE(PageLRU(page), page); SetPageLRU(page); add_page_to_lru_list(page, lruvec, page_lru(page)); } spin_unlock_irq(&pgdat->lru_lock); } static void commit_charge(struct page *page, struct mem_cgroup *memcg, bool lrucare) { int isolated; VM_BUG_ON_PAGE(page->mem_cgroup, page); /* * 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) lock_page_lru(page, &isolated); /* * Nobody should be changing or seriously looking at * page->mem_cgroup at this point: * * - the page is uncharged * * - the page is off-LRU * * - an anonymous fault has exclusive page access, except for * a locked page table * * - a page cache insertion, a swapin fault, or a migration * have the page locked */ page->mem_cgroup = memcg; if (lrucare) unlock_page_lru(page, isolated); } #ifdef CONFIG_MEMCG_KMEM /* * Returns a pointer to the memory cgroup to which the kernel object is charged. * * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(), * cgroup_mutex, etc. */ struct mem_cgroup *mem_cgroup_from_obj(void *p) { struct page *page; if (mem_cgroup_disabled()) return NULL; page = virt_to_head_page(p); /* * Slab pages don't have page->mem_cgroup set because corresponding * kmem caches can be reparented during the lifetime. That's why * memcg_from_slab_page() should be used instead. */ if (PageSlab(page)) return memcg_from_slab_page(page); /* All other pages use page->mem_cgroup */ return page->mem_cgroup; } static int memcg_alloc_cache_id(void) { int id, size; int err; id = ida_simple_get(&memcg_cache_ida, 0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL); if (id < 0) return id; if (id < memcg_nr_cache_ids) return id; /* * There's no space for the new id in memcg_caches arrays, * so we have to grow them. */ down_write(&memcg_cache_ids_sem); size = 2 * (id + 1); if (size < MEMCG_CACHES_MIN_SIZE) size = MEMCG_CACHES_MIN_SIZE; else if (size > MEMCG_CACHES_MAX_SIZE) size = MEMCG_CACHES_MAX_SIZE; err = memcg_update_all_caches(size); if (!err) err = memcg_update_all_list_lrus(size); if (!err) memcg_nr_cache_ids = size; up_write(&memcg_cache_ids_sem); if (err) { ida_simple_remove(&memcg_cache_ida, id); return err; } return id; } static void memcg_free_cache_id(int id) { ida_simple_remove(&memcg_cache_ida, id); } struct memcg_kmem_cache_create_work { struct mem_cgroup *memcg; struct kmem_cache *cachep; struct work_struct work; }; static void memcg_kmem_cache_create_func(struct work_struct *w) { struct memcg_kmem_cache_create_work *cw = container_of(w, struct memcg_kmem_cache_create_work, work); struct mem_cgroup *memcg = cw->memcg; struct kmem_cache *cachep = cw->cachep; memcg_create_kmem_cache(memcg, cachep); css_put(&memcg->css); kfree(cw); } /* * Enqueue the creation of a per-memcg kmem_cache. */ static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, struct kmem_cache *cachep) { struct memcg_kmem_cache_create_work *cw; if (!css_tryget_online(&memcg->css)) return; cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN); if (!cw) return; cw->memcg = memcg; cw->cachep = cachep; INIT_WORK(&cw->work, memcg_kmem_cache_create_func); queue_work(memcg_kmem_cache_wq, &cw->work); } static inline bool memcg_kmem_bypass(void) { if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD)) return true; return false; } /** * memcg_kmem_get_cache: select the correct per-memcg cache for allocation * @cachep: the original global kmem cache * * 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 * create it asynchronously in a workqueue and let the current allocation * go through with the original cache. * * This function takes a reference to the cache it returns to assure it * won't get destroyed while we are working with it. Once the caller is * done with it, memcg_kmem_put_cache() must be called to release the * reference. */ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep) { struct mem_cgroup *memcg; struct kmem_cache *memcg_cachep; struct memcg_cache_array *arr; int kmemcg_id; VM_BUG_ON(!is_root_cache(cachep)); if (memcg_kmem_bypass()) return cachep; rcu_read_lock(); if (unlikely(current->active_memcg)) memcg = current->active_memcg; else memcg = mem_cgroup_from_task(current); if (!memcg || memcg == root_mem_cgroup) goto out_unlock; kmemcg_id = READ_ONCE(memcg->kmemcg_id); if (kmemcg_id < 0) goto out_unlock; arr = rcu_dereference(cachep->memcg_params.memcg_caches); /* * Make sure we will access the up-to-date value. The code updating * memcg_caches issues a write barrier to match the data dependency * barrier inside READ_ONCE() (see memcg_create_kmem_cache()). */ memcg_cachep = READ_ONCE(arr->entries[kmemcg_id]); /* * 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 * memcg_create_kmem_cache, this means no further allocation * could happen with the slab_mutex held. So it's better to * defer everything. * * If the memcg is dying or memcg_cache is about to be released, * don't bother creating new kmem_caches. Because memcg_cachep * is ZEROed as the fist step of kmem offlining, we don't need * percpu_ref_tryget_live() here. css_tryget_online() check in * memcg_schedule_kmem_cache_create() will prevent us from * creation of a new kmem_cache. */ if (unlikely(!memcg_cachep)) memcg_schedule_kmem_cache_create(memcg, cachep); else if (percpu_ref_tryget(&memcg_cachep->memcg_params.refcnt)) cachep = memcg_cachep; out_unlock: rcu_read_unlock(); return cachep; } /** * memcg_kmem_put_cache: drop reference taken by memcg_kmem_get_cache * @cachep: the cache returned by memcg_kmem_get_cache */ void memcg_kmem_put_cache(struct kmem_cache *cachep) { if (!is_root_cache(cachep)) percpu_ref_put(&cachep->memcg_params.refcnt); } /** * __memcg_kmem_charge: charge a number of kernel pages to a memcg * @memcg: memory cgroup to charge * @gfp: reclaim mode * @nr_pages: number of pages to charge * * Returns 0 on success, an error code on failure. */ int __memcg_kmem_charge(struct mem_cgroup *memcg, gfp_t gfp, unsigned int nr_pages) { struct page_counter *counter; int ret; ret = try_charge(memcg, gfp, nr_pages); if (ret) return ret; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !page_counter_try_charge(&memcg->kmem, nr_pages, &counter)) { /* * Enforce __GFP_NOFAIL allocation because callers are not * prepared to see failures and likely do not have any failure * handling code. */ if (gfp & __GFP_NOFAIL) { page_counter_charge(&memcg->kmem, nr_pages); return 0; } cancel_charge(memcg, nr_pages); return -ENOMEM; } return 0; } /** * __memcg_kmem_uncharge: uncharge a number of kernel pages from a memcg * @memcg: memcg to uncharge * @nr_pages: number of pages to uncharge */ void __memcg_kmem_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages) { if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) page_counter_uncharge(&memcg->kmem, nr_pages); page_counter_uncharge(&memcg->memory, nr_pages); if (do_memsw_account()) page_counter_uncharge(&memcg->memsw, nr_pages); } /** * __memcg_kmem_charge_page: charge a kmem page to the current memory cgroup * @page: page to charge * @gfp: reclaim mode * @order: allocation order * * Returns 0 on success, an error code on failure. */ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order) { struct mem_cgroup *memcg; int ret = 0; if (memcg_kmem_bypass()) return 0; memcg = get_mem_cgroup_from_current(); if (!mem_cgroup_is_root(memcg)) { ret = __memcg_kmem_charge(memcg, gfp, 1 << order); if (!ret) { page->mem_cgroup = memcg; __SetPageKmemcg(page); } } css_put(&memcg->css); return ret; } /** * __memcg_kmem_uncharge_page: uncharge a kmem page * @page: page to uncharge * @order: allocation order */ void __memcg_kmem_uncharge_page(struct page *page, int order) { struct mem_cgroup *memcg = page->mem_cgroup; unsigned int nr_pages = 1 << order; if (!memcg) return; VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page); __memcg_kmem_uncharge(memcg, nr_pages); page->mem_cgroup = NULL; /* slab pages do not have PageKmemcg flag set */ if (PageKmemcg(page)) __ClearPageKmemcg(page); css_put_many(&memcg->css, nr_pages); } #endif /* CONFIG_MEMCG_KMEM */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* * Because tail pages are not marked as "used", set it. We're under * pgdat->lru_lock and migration entries setup in all page mappings. */ void mem_cgroup_split_huge_fixup(struct page *head) { int i; if (mem_cgroup_disabled()) return; for (i = 1; i < HPAGE_PMD_NR; i++) head[i].mem_cgroup = head->mem_cgroup; __mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PMD_NR); } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #ifdef CONFIG_MEMCG_SWAP /** * 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 page_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) { mod_memcg_state(from, MEMCG_SWAP, -1); mod_memcg_state(to, MEMCG_SWAP, 1); 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 static DEFINE_MUTEX(memcg_max_mutex); static int mem_cgroup_resize_max(struct mem_cgroup *memcg, unsigned long max, bool memsw) { bool enlarge = false; bool drained = false; int ret; bool limits_invariant; struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory; do { if (signal_pending(current)) { ret = -EINTR; break; } mutex_lock(&memcg_max_mutex); /* * Make sure that the new limit (memsw or memory limit) doesn't * break our basic invariant rule memory.max <= memsw.max. */ limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) : max <= memcg->memsw.max; if (!limits_invariant) { mutex_unlock(&memcg_max_mutex); ret = -EINVAL; break; } if (max > counter->max) enlarge = true; ret = page_counter_set_max(counter, max); mutex_unlock(&memcg_max_mutex); if (!ret) break; if (!drained) { drain_all_stock(memcg); drained = true; continue; } if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, !memsw)) { ret = -EBUSY; break; } } while (true); if (!ret && enlarge) memcg_oom_recover(memcg); return ret; } unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, gfp_t gfp_mask, unsigned long *total_scanned) { unsigned long nr_reclaimed = 0; struct mem_cgroup_per_node *mz, *next_mz = NULL; unsigned long reclaimed; int loop = 0; struct mem_cgroup_tree_per_node *mctz; unsigned long excess; unsigned long nr_scanned; if (order > 0) return 0; mctz = soft_limit_tree_node(pgdat->node_id); /* * Do not even bother to check the largest node if the root * is empty. Do it lockless to prevent lock bouncing. Races * are acceptable as soft limit is best effort anyway. */ if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root)) return 0; /* * This loop can run a while, specially if mem_cgroup's continuously * keep exceeding their soft limit and putting the system under * pressure */ do { if (next_mz) mz = next_mz; else mz = mem_cgroup_largest_soft_limit_node(mctz); if (!mz) break; nr_scanned = 0; reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat, gfp_mask, &nr_scanned); nr_reclaimed += reclaimed; *total_scanned += nr_scanned; spin_lock_irq(&mctz->lock); __mem_cgroup_remove_exceeded(mz, mctz); /* * If we failed to reclaim anything from this memory cgroup * it is time to move on to the next cgroup */ next_mz = NULL; if (!reclaimed) next_mz = __mem_cgroup_largest_soft_limit_node(mctz); excess = soft_limit_excess(mz->memcg); /* * One school of thought says that we should not add * back the node to the tree if reclaim returns 0. * But our reclaim could return 0, simply because due * to priority we are exposing a smaller subset of * memory to reclaim from. Consider this as a longer * term TODO. */ /* If excess == 0, no tree ops */ __mem_cgroup_insert_exceeded(mz, mctz, excess); spin_unlock_irq(&mctz->lock); css_put(&mz->memcg->css); loop++; /* * Could not reclaim anything and there are no more * mem cgroups to try or we seem to be looping without * reclaiming anything. */ if (!nr_reclaimed && (next_mz == NULL || loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) break; } while (!nr_reclaimed); if (next_mz) css_put(&next_mz->memcg->css); return nr_reclaimed; } /* * Test whether @memcg has children, dead or alive. Note that this * function doesn't care whether @memcg has use_hierarchy enabled and * returns %true if there are child csses according to the cgroup * hierarchy. Testing use_hierarchy is the caller's responsiblity. */ static inline bool memcg_has_children(struct mem_cgroup *memcg) { bool ret; rcu_read_lock(); ret = css_next_child(NULL, &memcg->css); rcu_read_unlock(); return ret; } /* * Reclaims as many pages from the given memcg as possible. * * 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; /* we call try-to-free pages for make this cgroup empty */ lru_add_drain_all(); drain_all_stock(memcg); /* try to free all pages in this cgroup */ while (nr_retries && page_counter_read(&memcg->memory)) { int progress; if (signal_pending(current)) return -EINTR; progress = try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true); if (!progress) { nr_retries--; /* maybe some writeback is necessary */ congestion_wait(BLK_RW_ASYNC, HZ/10); } } return 0; } static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); if (mem_cgroup_is_root(memcg)) return -EINVAL; return mem_cgroup_force_empty(memcg) ?: nbytes; } 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(memcg->css.parent); if (memcg->use_hierarchy == val) return 0; /* * 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; return retval; } static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) { unsigned long val; if (mem_cgroup_is_root(memcg)) { val = memcg_page_state(memcg, MEMCG_CACHE) + memcg_page_state(memcg, MEMCG_RSS); if (swap) val += memcg_page_state(memcg, MEMCG_SWAP); } else { if (!swap) val = page_counter_read(&memcg->memory); else val = page_counter_read(&memcg->memsw); } return val; } enum { RES_USAGE, RES_LIMIT, RES_MAX_USAGE, RES_FAILCNT, RES_SOFT_LIMIT, }; static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, struct cftype *cft) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct page_counter *counter; switch (MEMFILE_TYPE(cft->private)) { case _MEM: counter = &memcg->memory; break; case _MEMSWAP: counter = &memcg->memsw; break; case _KMEM: counter = &memcg->kmem; break; case _TCP: counter = &memcg->tcpmem; break; default: BUG(); } switch (MEMFILE_ATTR(cft->private)) { case RES_USAGE: if (counter == &memcg->memory) return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE; if (counter == &memcg->memsw) return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE; return (u64)page_counter_read(counter) * PAGE_SIZE; case RES_LIMIT: return (u64)counter->max * PAGE_SIZE; case RES_MAX_USAGE: return (u64)counter->watermark * PAGE_SIZE; case RES_FAILCNT: return counter->failcnt; case RES_SOFT_LIMIT: return (u64)memcg->soft_limit * PAGE_SIZE; default: BUG(); } } static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg) { unsigned long stat[MEMCG_NR_STAT] = {0}; struct mem_cgroup *mi; int node, cpu, i; for_each_online_cpu(cpu) for (i = 0; i < MEMCG_NR_STAT; i++) stat[i] += per_cpu(memcg->vmstats_percpu->stat[i], cpu); for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) for (i = 0; i < MEMCG_NR_STAT; i++) atomic_long_add(stat[i], &mi->vmstats[i]); for_each_node(node) { struct mem_cgroup_per_node *pn = memcg->nodeinfo[node]; struct mem_cgroup_per_node *pi; for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) stat[i] = 0; for_each_online_cpu(cpu) for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) stat[i] += per_cpu( pn->lruvec_stat_cpu->count[i], cpu); for (pi = pn; pi; pi = parent_nodeinfo(pi, node)) for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) atomic_long_add(stat[i], &pi->lruvec_stat[i]); } } static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg) { unsigned long events[NR_VM_EVENT_ITEMS]; struct mem_cgroup *mi; int cpu, i; for (i = 0; i < NR_VM_EVENT_ITEMS; i++) events[i] = 0; for_each_online_cpu(cpu) for (i = 0; i < NR_VM_EVENT_ITEMS; i++) events[i] += per_cpu(memcg->vmstats_percpu->events[i], cpu); for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) for (i = 0; i < NR_VM_EVENT_ITEMS; i++) atomic_long_add(events[i], &mi->vmevents[i]); } #ifdef CONFIG_MEMCG_KMEM static int memcg_online_kmem(struct mem_cgroup *memcg) { int memcg_id; if (cgroup_memory_nokmem) return 0; BUG_ON(memcg->kmemcg_id >= 0); BUG_ON(memcg->kmem_state); memcg_id = memcg_alloc_cache_id(); if (memcg_id < 0) return memcg_id; static_branch_inc(&memcg_kmem_enabled_key); /* * A memory cgroup is considered kmem-online as soon as it gets * kmemcg_id. Setting the id after enabling static branching will * guarantee no one starts accounting before all call sites are * patched. */ memcg->kmemcg_id = memcg_id; memcg->kmem_state = KMEM_ONLINE; INIT_LIST_HEAD(&memcg->kmem_caches); return 0; } static void memcg_offline_kmem(struct mem_cgroup *memcg) { struct cgroup_subsys_state *css; struct mem_cgroup *parent, *child; int kmemcg_id; if (memcg->kmem_state != KMEM_ONLINE) return; /* * Clear the online state before clearing memcg_caches array * entries. The slab_mutex in memcg_deactivate_kmem_caches() * guarantees that no cache will be created for this cgroup * after we are done (see memcg_create_kmem_cache()). */ memcg->kmem_state = KMEM_ALLOCATED; parent = parent_mem_cgroup(memcg); if (!parent) parent = root_mem_cgroup; /* * Deactivate and reparent kmem_caches. */ memcg_deactivate_kmem_caches(memcg, parent); kmemcg_id = memcg->kmemcg_id; BUG_ON(kmemcg_id < 0); /* * Change kmemcg_id of this cgroup and all its descendants to the * parent's id, and then move all entries from this cgroup's list_lrus * to ones of the parent. After we have finished, all list_lrus * corresponding to this cgroup are guaranteed to remain empty. The * ordering is imposed by list_lru_node->lock taken by * memcg_drain_all_list_lrus(). */ rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */ css_for_each_descendant_pre(css, &memcg->css) { child = mem_cgroup_from_css(css); BUG_ON(child->kmemcg_id != kmemcg_id); child->kmemcg_id = parent->kmemcg_id; if (!memcg->use_hierarchy) break; } rcu_read_unlock(); memcg_drain_all_list_lrus(kmemcg_id, parent); memcg_free_cache_id(kmemcg_id); } static void memcg_free_kmem(struct mem_cgroup *memcg) { /* css_alloc() failed, offlining didn't happen */ if (unlikely(memcg->kmem_state == KMEM_ONLINE)) memcg_offline_kmem(memcg); if (memcg->kmem_state == KMEM_ALLOCATED) { WARN_ON(!list_empty(&memcg->kmem_caches)); static_branch_dec(&memcg_kmem_enabled_key); } } #else static int memcg_online_kmem(struct mem_cgroup *memcg) { return 0; } static void memcg_offline_kmem(struct mem_cgroup *memcg) { } static void memcg_free_kmem(struct mem_cgroup *memcg) { } #endif /* CONFIG_MEMCG_KMEM */ static int memcg_update_kmem_max(struct mem_cgroup *memcg, unsigned long max) { int ret; mutex_lock(&memcg_max_mutex); ret = page_counter_set_max(&memcg->kmem, max); mutex_unlock(&memcg_max_mutex); return ret; } static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max) { int ret; mutex_lock(&memcg_max_mutex); ret = page_counter_set_max(&memcg->tcpmem, max); if (ret) goto out; if (!memcg->tcpmem_active) { /* * The active flag needs to be written after the static_key * update. This is what guarantees that the socket activation * function is the last one to run. See mem_cgroup_sk_alloc() * for details, and note that we don't mark any socket as * belonging to this memcg until that flag is up. * * We need to do this, because static_keys will span multiple * sites, but we can't control their order. If we mark a socket * as accounted, but the accounting functions are not patched in * yet, we'll lose accounting. * * We never race with the readers in mem_cgroup_sk_alloc(), * because when this value change, the code to process it is not * patched in yet. */ static_branch_inc(&memcg_sockets_enabled_key); memcg->tcpmem_active = true; } out: mutex_unlock(&memcg_max_mutex); return ret; } /* * The user of this function is... * RES_LIMIT. */ static ssize_t mem_cgroup_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned long nr_pages; int ret; buf = strstrip(buf); ret = page_counter_memparse(buf, "-1", &nr_pages); if (ret) return ret; switch (MEMFILE_ATTR(of_cft(of)->private)) { case RES_LIMIT: if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */ ret = -EINVAL; break; } switch (MEMFILE_TYPE(of_cft(of)->private)) { case _MEM: ret = mem_cgroup_resize_max(memcg, nr_pages, false); break; case _MEMSWAP: ret = mem_cgroup_resize_max(memcg, nr_pages, true); break; case _KMEM: pr_warn_once("kmem.limit_in_bytes is deprecated and will be removed. " "Please report your usecase to linux-mm@kvack.org if you " "depend on this functionality.\n"); ret = memcg_update_kmem_max(memcg, nr_pages); break; case _TCP: ret = memcg_update_tcp_max(memcg, nr_pages); break; } break; case RES_SOFT_LIMIT: memcg->soft_limit = nr_pages; ret = 0; break; } return ret ?: nbytes; } static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); struct page_counter *counter; switch (MEMFILE_TYPE(of_cft(of)->private)) { case _MEM: counter = &memcg->memory; break; case _MEMSWAP: counter = &memcg->memsw; break; case _KMEM: counter = &memcg->kmem; break; case _TCP: counter = &memcg->tcpmem; break; default: BUG(); } switch (MEMFILE_ATTR(of_cft(of)->private)) { case RES_MAX_USAGE: page_counter_reset_watermark(counter); break; case RES_FAILCNT: counter->failcnt = 0; break; default: BUG(); } return nbytes; } 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 & ~MOVE_MASK) 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 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE)) #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON)) #define LRU_ALL ((1 << NR_LRU_LISTS) - 1) static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, int nid, unsigned int lru_mask) { struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); unsigned long nr = 0; enum lru_list lru; VM_BUG_ON((unsigned)nid >= nr_node_ids); for_each_lru(lru) { if (!(BIT(lru) & lru_mask)) continue; nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru); } return nr; } static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, unsigned int lru_mask) { unsigned long nr = 0; enum lru_list lru; for_each_lru(lru) { if (!(BIT(lru) & lru_mask)) continue; nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru); } return nr; } static int memcg_numa_stat_show(struct seq_file *m, void *v) { struct numa_stat { const char *name; unsigned int lru_mask; }; static const struct numa_stat stats[] = { { "total", LRU_ALL }, { "file", LRU_ALL_FILE }, { "anon", LRU_ALL_ANON }, { "unevictable", BIT(LRU_UNEVICTABLE) }, }; const struct numa_stat *stat; int nid; unsigned long nr; struct mem_cgroup *memcg = mem_cgroup_from_seq(m); for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask); seq_printf(m, "%s=%lu", stat->name, nr); for_each_node_state(nid, N_MEMORY) { nr = mem_cgroup_node_nr_lru_pages(memcg, nid, stat->lru_mask); seq_printf(m, " N%d=%lu", nid, nr); } seq_putc(m, '\n'); } for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { struct mem_cgroup *iter; nr = 0; for_each_mem_cgroup_tree(iter, memcg) nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask); seq_printf(m, "hierarchical_%s=%lu", stat->name, nr); for_each_node_state(nid, N_MEMORY) { nr = 0; for_each_mem_cgroup_tree(iter, memcg) nr += mem_cgroup_node_nr_lru_pages( iter, nid, stat->lru_mask); seq_printf(m, " N%d=%lu", nid, nr); } seq_putc(m, '\n'); } return 0; } #endif /* CONFIG_NUMA */ static const unsigned int memcg1_stats[] = { MEMCG_CACHE, MEMCG_RSS, MEMCG_RSS_HUGE, NR_SHMEM, NR_FILE_MAPPED, NR_FILE_DIRTY, NR_WRITEBACK, MEMCG_SWAP, }; static const char *const memcg1_stat_names[] = { "cache", "rss", "rss_huge", "shmem", "mapped_file", "dirty", "writeback", "swap", }; /* Universal VM events cgroup1 shows, original sort order */ static const unsigned int memcg1_events[] = { PGPGIN, PGPGOUT, PGFAULT, PGMAJFAULT, }; static int memcg_stat_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); unsigned long memory, memsw; struct mem_cgroup *mi; unsigned int i; BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats)); for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) continue; seq_printf(m, "%s %lu\n", memcg1_stat_names[i], memcg_page_state_local(memcg, memcg1_stats[i]) * PAGE_SIZE); } for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) seq_printf(m, "%s %lu\n", vm_event_name(memcg1_events[i]), memcg_events_local(memcg, memcg1_events[i])); for (i = 0; i < NR_LRU_LISTS; i++) seq_printf(m, "%s %lu\n", lru_list_name(i), memcg_page_state_local(memcg, NR_LRU_BASE + i) * PAGE_SIZE); /* Hierarchical information */ memory = memsw = PAGE_COUNTER_MAX; for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) { memory = min(memory, READ_ONCE(mi->memory.max)); memsw = min(memsw, READ_ONCE(mi->memsw.max)); } seq_printf(m, "hierarchical_memory_limit %llu\n", (u64)memory * PAGE_SIZE); if (do_memsw_account()) seq_printf(m, "hierarchical_memsw_limit %llu\n", (u64)memsw * PAGE_SIZE); for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) continue; seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], (u64)memcg_page_state(memcg, memcg1_stats[i]) * PAGE_SIZE); } for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) seq_printf(m, "total_%s %llu\n", vm_event_name(memcg1_events[i]), (u64)memcg_events(memcg, memcg1_events[i])); for (i = 0; i < NR_LRU_LISTS; i++) seq_printf(m, "total_%s %llu\n", lru_list_name(i), (u64)memcg_page_state(memcg, NR_LRU_BASE + i) * PAGE_SIZE); #ifdef CONFIG_DEBUG_VM { pg_data_t *pgdat; struct mem_cgroup_per_node *mz; struct zone_reclaim_stat *rstat; unsigned long recent_rotated[2] = {0, 0}; unsigned long recent_scanned[2] = {0, 0}; for_each_online_pgdat(pgdat) { mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id); 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); if (val > 100) return -EINVAL; if (css->parent) memcg->swappiness = val; else vm_swappiness = val; return 0; } static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) { struct mem_cgroup_threshold_ary *t; unsigned long 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_memsw_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; spin_lock(&memcg_oom_lock); list_for_each_entry(ev, &memcg->oom_notify, list) eventfd_signal(ev->eventfd, 1); spin_unlock(&memcg_oom_lock); 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 mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args, enum res_type type) { struct mem_cgroup_thresholds *thresholds; struct mem_cgroup_threshold_ary *new; unsigned long threshold; unsigned long usage; int i, size, ret; ret = page_counter_memparse(args, "-1", &threshold); if (ret) return ret; mutex_lock(&memcg->thresholds_lock); if (type == _MEM) { thresholds = &memcg->thresholds; usage = mem_cgroup_usage(memcg, false); } else if (type == _MEMSWAP) { thresholds = &memcg->memsw_thresholds; usage = mem_cgroup_usage(memcg, true); } else BUG(); /* 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(struct_size(new, entries, size), 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 int mem_cgroup_usage_register_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args) { return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM); } static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args) { return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP); } static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, enum res_type type) { struct mem_cgroup_thresholds *thresholds; struct mem_cgroup_threshold_ary *new; unsigned long usage; int i, j, size, entries; mutex_lock(&memcg->thresholds_lock); if (type == _MEM) { thresholds = &memcg->thresholds; usage = mem_cgroup_usage(memcg, false); } else if (type == _MEMSWAP) { thresholds = &memcg->memsw_thresholds; usage = mem_cgroup_usage(memcg, true); } else BUG(); if (!thresholds->primary) goto unlock; /* Check if a threshold crossed before removing */ __mem_cgroup_threshold(memcg, type == _MEMSWAP); /* Calculate new number of threshold */ size = entries = 0; for (i = 0; i < thresholds->primary->size; i++) { if (thresholds->primary->entries[i].eventfd != eventfd) size++; else entries++; } new = thresholds->spare; /* If no items related to eventfd have been cleared, nothing to do */ if (!entries) goto unlock; /* 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; rcu_assign_pointer(thresholds->primary, new); /* To be sure that nobody uses thresholds */ synchronize_rcu(); /* If all events are unregistered, free the spare array */ if (!new) { kfree(thresholds->spare); thresholds->spare = NULL; } unlock: mutex_unlock(&memcg->thresholds_lock); } static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd) { return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM); } static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd) { return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP); } static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd, const char *args) { struct mem_cgroup_eventfd_list *event; 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 (memcg->under_oom) eventfd_signal(eventfd, 1); spin_unlock(&memcg_oom_lock); return 0; } static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg, struct eventfd_ctx *eventfd) { struct mem_cgroup_eventfd_list *ev, *tmp; 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 seq_file *sf, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(sf); seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable); seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom); seq_printf(sf, "oom_kill %lu\n", atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL])); 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); /* cannot set to root cgroup and only 0 and 1 are allowed */ if (!css->parent || !((val == 0) || (val == 1))) return -EINVAL; memcg->oom_kill_disable = val; if (!val) memcg_oom_recover(memcg); return 0; } #ifdef CONFIG_CGROUP_WRITEBACK #include static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) { return wb_domain_init(&memcg->cgwb_domain, gfp); } static void memcg_wb_domain_exit(struct mem_cgroup *memcg) { wb_domain_exit(&memcg->cgwb_domain); } static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg) { wb_domain_size_changed(&memcg->cgwb_domain); } struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb) { struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); if (!memcg->css.parent) return NULL; return &memcg->cgwb_domain; } /* * idx can be of type enum memcg_stat_item or node_stat_item. * Keep in sync with memcg_exact_page(). */ static unsigned long memcg_exact_page_state(struct mem_cgroup *memcg, int idx) { long x = atomic_long_read(&memcg->vmstats[idx]); int cpu; for_each_online_cpu(cpu) x += per_cpu_ptr(memcg->vmstats_percpu, cpu)->stat[idx]; if (x < 0) x = 0; return x; } /** * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg * @wb: bdi_writeback in question * @pfilepages: out parameter for number of file pages * @pheadroom: out parameter for number of allocatable pages according to memcg * @pdirty: out parameter for number of dirty pages * @pwriteback: out parameter for number of pages under writeback * * Determine the numbers of file, headroom, dirty, and writeback pages in * @wb's memcg. File, dirty and writeback are self-explanatory. Headroom * is a bit more involved. * * A memcg's headroom is "min(max, high) - used". In the hierarchy, the * headroom is calculated as the lowest headroom of itself and the * ancestors. Note that this doesn't consider the actual amount of * available memory in the system. The caller should further cap * *@pheadroom accordingly. */ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages, unsigned long *pheadroom, unsigned long *pdirty, unsigned long *pwriteback) { struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); struct mem_cgroup *parent; *pdirty = memcg_exact_page_state(memcg, NR_FILE_DIRTY); *pwriteback = memcg_exact_page_state(memcg, NR_WRITEBACK); *pfilepages = memcg_exact_page_state(memcg, NR_INACTIVE_FILE) + memcg_exact_page_state(memcg, NR_ACTIVE_FILE); *pheadroom = PAGE_COUNTER_MAX; while ((parent = parent_mem_cgroup(memcg))) { unsigned long ceiling = min(READ_ONCE(memcg->memory.max), READ_ONCE(memcg->memory.high)); unsigned long used = page_counter_read(&memcg->memory); *pheadroom = min(*pheadroom, ceiling - min(ceiling, used)); memcg = parent; } } /* * Foreign dirty flushing * * There's an inherent mismatch between memcg and writeback. The former * trackes ownership per-page while the latter per-inode. This was a * deliberate design decision because honoring per-page ownership in the * writeback path is complicated, may lead to higher CPU and IO overheads * and deemed unnecessary given that write-sharing an inode across * different cgroups isn't a common use-case. * * Combined with inode majority-writer ownership switching, this works well * enough in most cases but there are some pathological cases. For * example, let's say there are two cgroups A and B which keep writing to * different but confined parts of the same inode. B owns the inode and * A's memory is limited far below B's. A's dirty ratio can rise enough to * trigger balance_dirty_pages() sleeps but B's can be low enough to avoid * triggering background writeback. A will be slowed down without a way to * make writeback of the dirty pages happen. * * Conditions like the above can lead to a cgroup getting repatedly and * severely throttled after making some progress after each * dirty_expire_interval while the underyling IO device is almost * completely idle. * * Solving this problem completely requires matching the ownership tracking * granularities between memcg and writeback in either direction. However, * the more egregious behaviors can be avoided by simply remembering the * most recent foreign dirtying events and initiating remote flushes on * them when local writeback isn't enough to keep the memory clean enough. * * The following two functions implement such mechanism. When a foreign * page - a page whose memcg and writeback ownerships don't match - is * dirtied, mem_cgroup_track_foreign_dirty() records the inode owning * bdi_writeback on the page owning memcg. When balance_dirty_pages() * decides that the memcg needs to sleep due to high dirty ratio, it calls * mem_cgroup_flush_foreign() which queues writeback on the recorded * foreign bdi_writebacks which haven't expired. Both the numbers of * recorded bdi_writebacks and concurrent in-flight foreign writebacks are * limited to MEMCG_CGWB_FRN_CNT. * * The mechanism only remembers IDs and doesn't hold any object references. * As being wrong occasionally doesn't matter, updates and accesses to the * records are lockless and racy. */ void mem_cgroup_track_foreign_dirty_slowpath(struct page *page, struct bdi_writeback *wb) { struct mem_cgroup *memcg = page->mem_cgroup; struct memcg_cgwb_frn *frn; u64 now = get_jiffies_64(); u64 oldest_at = now; int oldest = -1; int i; trace_track_foreign_dirty(page, wb); /* * Pick the slot to use. If there is already a slot for @wb, keep * using it. If not replace the oldest one which isn't being * written out. */ for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) { frn = &memcg->cgwb_frn[i]; if (frn->bdi_id == wb->bdi->id && frn->memcg_id == wb->memcg_css->id) break; if (time_before64(frn->at, oldest_at) && atomic_read(&frn->done.cnt) == 1) { oldest = i; oldest_at = frn->at; } } if (i < MEMCG_CGWB_FRN_CNT) { /* * Re-using an existing one. Update timestamp lazily to * avoid making the cacheline hot. We want them to be * reasonably up-to-date and significantly shorter than * dirty_expire_interval as that's what expires the record. * Use the shorter of 1s and dirty_expire_interval / 8. */ unsigned long update_intv = min_t(unsigned long, HZ, msecs_to_jiffies(dirty_expire_interval * 10) / 8); if (time_before64(frn->at, now - update_intv)) frn->at = now; } else if (oldest >= 0) { /* replace the oldest free one */ frn = &memcg->cgwb_frn[oldest]; frn->bdi_id = wb->bdi->id; frn->memcg_id = wb->memcg_css->id; frn->at = now; } } /* issue foreign writeback flushes for recorded foreign dirtying events */ void mem_cgroup_flush_foreign(struct bdi_writeback *wb) { struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10); u64 now = jiffies_64; int i; for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) { struct memcg_cgwb_frn *frn = &memcg->cgwb_frn[i]; /* * If the record is older than dirty_expire_interval, * writeback on it has already started. No need to kick it * off again. Also, don't start a new one if there's * already one in flight. */ if (time_after64(frn->at, now - intv) && atomic_read(&frn->done.cnt) == 1) { frn->at = 0; trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id); cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, 0, WB_REASON_FOREIGN_FLUSH, &frn->done); } } } #else /* CONFIG_CGROUP_WRITEBACK */ static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) { return 0; } static void memcg_wb_domain_exit(struct mem_cgroup *memcg) { } static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg) { } #endif /* CONFIG_CGROUP_WRITEBACK */ /* * DO NOT USE IN NEW FILES. * * "cgroup.event_control" implementation. * * This is way over-engineered. It tries to support fully configurable * events for each user. Such level of flexibility is completely * unnecessary especially in the light of the planned unified hierarchy. * * Please deprecate this and replace with something simpler if at all * possible. */ /* * Unregister event and free resources. * * Gets called from workqueue. */ static void memcg_event_remove(struct work_struct *work) { struct mem_cgroup_event *event = container_of(work, struct mem_cgroup_event, remove); struct mem_cgroup *memcg = event->memcg; remove_wait_queue(event->wqh, &event->wait); event->unregister_event(memcg, event->eventfd); /* Notify userspace the event is going away. */ eventfd_signal(event->eventfd, 1); eventfd_ctx_put(event->eventfd); kfree(event); css_put(&memcg->css); } /* * Gets called on EPOLLHUP on eventfd when user closes it. * * Called with wqh->lock held and interrupts disabled. */ static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) { struct mem_cgroup_event *event = container_of(wait, struct mem_cgroup_event, wait); struct mem_cgroup *memcg = event->memcg; __poll_t flags = key_to_poll(key); if (flags & EPOLLHUP) { /* * If the event has been detached at cgroup removal, we * can simply return knowing the other side will cleanup * for us. * * We can't race against event freeing since the other * side will require wqh->lock via remove_wait_queue(), * which we hold. */ spin_lock(&memcg->event_list_lock); if (!list_empty(&event->list)) { list_del_init(&event->list); /* * We are in atomic context, but cgroup_event_remove() * may sleep, so we have to call it in workqueue. */ schedule_work(&event->remove); } spin_unlock(&memcg->event_list_lock); } return 0; } static void memcg_event_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh, poll_table *pt) { struct mem_cgroup_event *event = container_of(pt, struct mem_cgroup_event, pt); event->wqh = wqh; add_wait_queue(wqh, &event->wait); } /* * DO NOT USE IN NEW FILES. * * Parse input and register new cgroup event handler. * * Input must be in format ' '. * Interpretation of args is defined by control file implementation. */ static ssize_t memcg_write_event_control(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct cgroup_subsys_state *css = of_css(of); struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_event *event; struct cgroup_subsys_state *cfile_css; unsigned int efd, cfd; struct fd efile; struct fd cfile; const char *name; char *endp; int ret; buf = strstrip(buf); efd = simple_strtoul(buf, &endp, 10); if (*endp != ' ') return -EINVAL; buf = endp + 1; cfd = simple_strtoul(buf, &endp, 10); if ((*endp != ' ') && (*endp != '\0')) return -EINVAL; buf = endp + 1; event = kzalloc(sizeof(*event), GFP_KERNEL); if (!event) return -ENOMEM; event->memcg = memcg; INIT_LIST_HEAD(&event->list); init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc); init_waitqueue_func_entry(&event->wait, memcg_event_wake); INIT_WORK(&event->remove, memcg_event_remove); efile = fdget(efd); if (!efile.file) { ret = -EBADF; goto out_kfree; } event->eventfd = eventfd_ctx_fileget(efile.file); if (IS_ERR(event->eventfd)) { ret = PTR_ERR(event->eventfd); goto out_put_efile; } cfile = fdget(cfd); if (!cfile.file) { ret = -EBADF; goto out_put_eventfd; } /* the process need read permission on control file */ /* AV: shouldn't we check that it's been opened for read instead? */ ret = inode_permission(file_inode(cfile.file), MAY_READ); if (ret < 0) goto out_put_cfile; /* * Determine the event callbacks and set them in @event. This used * to be done via struct cftype but cgroup core no longer knows * about these events. The following is crude but the whole thing * is for compatibility anyway. * * DO NOT ADD NEW FILES. */ name = cfile.file->f_path.dentry->d_name.name; if (!strcmp(name, "memory.usage_in_bytes")) { event->register_event = mem_cgroup_usage_register_event; event->unregister_event = mem_cgroup_usage_unregister_event; } else if (!strcmp(name, "memory.oom_control")) { event->register_event = mem_cgroup_oom_register_event; event->unregister_event = mem_cgroup_oom_unregister_event; } else if (!strcmp(name, "memory.pressure_level")) { event->register_event = vmpressure_register_event; event->unregister_event = vmpressure_unregister_event; } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) { event->register_event = memsw_cgroup_usage_register_event; event->unregister_event = memsw_cgroup_usage_unregister_event; } else { ret = -EINVAL; goto out_put_cfile; } /* * Verify @cfile should belong to @css. Also, remaining events are * automatically removed on cgroup destruction but the removal is * asynchronous, so take an extra ref on @css. */ cfile_css = css_tryget_online_from_dir(cfile.file->f_path.dentry->d_parent, &memory_cgrp_subsys); ret = -EINVAL; if (IS_ERR(cfile_css)) goto out_put_cfile; if (cfile_css != css) { css_put(cfile_css); goto out_put_cfile; } ret = event->register_event(memcg, event->eventfd, buf); if (ret) goto out_put_css; vfs_poll(efile.file, &event->pt); spin_lock(&memcg->event_list_lock); list_add(&event->list, &memcg->event_list); spin_unlock(&memcg->event_list_lock); fdput(cfile); fdput(efile); return nbytes; out_put_css: css_put(css); out_put_cfile: fdput(cfile); out_put_eventfd: eventfd_ctx_put(event->eventfd); out_put_efile: fdput(efile); out_kfree: kfree(event); return ret; } static struct cftype mem_cgroup_legacy_files[] = { { .name = "usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), .read_u64 = mem_cgroup_read_u64, }, { .name = "max_usage_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "limit_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT), .write = mem_cgroup_write, .read_u64 = mem_cgroup_read_u64, }, { .name = "soft_limit_in_bytes", .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), .write = mem_cgroup_write, .read_u64 = mem_cgroup_read_u64, }, { .name = "failcnt", .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "stat", .seq_show = memcg_stat_show, }, { .name = "force_empty", .write = mem_cgroup_force_empty_write, }, { .name = "use_hierarchy", .write_u64 = mem_cgroup_hierarchy_write, .read_u64 = mem_cgroup_hierarchy_read, }, { .name = "cgroup.event_control", /* XXX: for compat */ .write = memcg_write_event_control, .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE, }, { .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", .seq_show = mem_cgroup_oom_control_read, .write_u64 = mem_cgroup_oom_control_write, .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), }, { .name = "pressure_level", }, #ifdef CONFIG_NUMA { .name = "numa_stat", .seq_show = memcg_numa_stat_show, }, #endif { .name = "kmem.limit_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), .write = mem_cgroup_write, .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.failcnt", .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, #if defined(CONFIG_MEMCG_KMEM) && \ (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)) { .name = "kmem.slabinfo", .seq_start = memcg_slab_start, .seq_next = memcg_slab_next, .seq_stop = memcg_slab_stop, .seq_show = memcg_slab_show, }, #endif { .name = "kmem.tcp.limit_in_bytes", .private = MEMFILE_PRIVATE(_TCP, RES_LIMIT), .write = mem_cgroup_write, .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.tcp.usage_in_bytes", .private = MEMFILE_PRIVATE(_TCP, RES_USAGE), .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.tcp.failcnt", .private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.tcp.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { }, /* terminate */ }; /* * Private memory cgroup IDR * * Swap-out records and page cache shadow entries need to store memcg * references in constrained space, so we maintain an ID space that is * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of * memory-controlled cgroups to 64k. * * However, there usually are many references to the oflline CSS after * the cgroup has been destroyed, such as page cache or reclaimable * slab objects, that don't need to hang on to the ID. We want to keep * those dead CSS from occupying IDs, or we might quickly exhaust the * relatively small ID space and prevent the creation of new cgroups * even when there are much fewer than 64k cgroups - possibly none. * * Maintain a private 16-bit ID space for memcg, and allow the ID to * be freed and recycled when it's no longer needed, which is usually * when the CSS is offlined. * * The only exception to that are records of swapped out tmpfs/shmem * pages that need to be attributed to live ancestors on swapin. But * those references are manageable from userspace. */ static DEFINE_IDR(mem_cgroup_idr); static void mem_cgroup_id_remove(struct mem_cgroup *memcg) { if (memcg->id.id > 0) { idr_remove(&mem_cgroup_idr, memcg->id.id); memcg->id.id = 0; } } static void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) { refcount_add(n, &memcg->id.ref); } static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) { if (refcount_sub_and_test(n, &memcg->id.ref)) { mem_cgroup_id_remove(memcg); /* Memcg ID pins CSS */ css_put(&memcg->css); } } static inline void mem_cgroup_id_put(struct mem_cgroup *memcg) { mem_cgroup_id_put_many(memcg, 1); } /** * mem_cgroup_from_id - look up a memcg from a memcg id * @id: the memcg id to look up * * Caller must hold rcu_read_lock(). */ struct mem_cgroup *mem_cgroup_from_id(unsigned short id) { WARN_ON_ONCE(!rcu_read_lock_held()); return idr_find(&mem_cgroup_idr, id); } static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn; int 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; pn->lruvec_stat_local = alloc_percpu(struct lruvec_stat); if (!pn->lruvec_stat_local) { kfree(pn); return 1; } pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat); if (!pn->lruvec_stat_cpu) { free_percpu(pn->lruvec_stat_local); kfree(pn); return 1; } lruvec_init(&pn->lruvec); pn->usage_in_excess = 0; pn->on_tree = false; pn->memcg = memcg; memcg->nodeinfo[node] = pn; return 0; } static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn = memcg->nodeinfo[node]; if (!pn) return; free_percpu(pn->lruvec_stat_cpu); free_percpu(pn->lruvec_stat_local); kfree(pn); } static void __mem_cgroup_free(struct mem_cgroup *memcg) { int node; for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); free_percpu(memcg->vmstats_percpu); free_percpu(memcg->vmstats_local); kfree(memcg); } static void mem_cgroup_free(struct mem_cgroup *memcg) { memcg_wb_domain_exit(memcg); /* * Flush percpu vmstats and vmevents to guarantee the value correctness * on parent's and all ancestor levels. */ memcg_flush_percpu_vmstats(memcg); memcg_flush_percpu_vmevents(memcg); __mem_cgroup_free(memcg); } static struct mem_cgroup *mem_cgroup_alloc(void) { struct mem_cgroup *memcg; unsigned int size; int node; int __maybe_unused i; long error = -ENOMEM; size = sizeof(struct mem_cgroup); size += nr_node_ids * sizeof(struct mem_cgroup_per_node *); memcg = kzalloc(size, GFP_KERNEL); if (!memcg) return ERR_PTR(error); memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL, 1, MEM_CGROUP_ID_MAX, GFP_KERNEL); if (memcg->id.id < 0) { error = memcg->id.id; goto fail; } memcg->vmstats_local = alloc_percpu(struct memcg_vmstats_percpu); if (!memcg->vmstats_local) goto fail; memcg->vmstats_percpu = alloc_percpu(struct memcg_vmstats_percpu); if (!memcg->vmstats_percpu) goto fail; for_each_node(node) if (alloc_mem_cgroup_per_node_info(memcg, node)) goto fail; if (memcg_wb_domain_init(memcg, GFP_KERNEL)) goto fail; INIT_WORK(&memcg->high_work, high_work_func); INIT_LIST_HEAD(&memcg->oom_notify); mutex_init(&memcg->thresholds_lock); spin_lock_init(&memcg->move_lock); vmpressure_init(&memcg->vmpressure); INIT_LIST_HEAD(&memcg->event_list); spin_lock_init(&memcg->event_list_lock); memcg->socket_pressure = jiffies; #ifdef CONFIG_MEMCG_KMEM memcg->kmemcg_id = -1; #endif #ifdef CONFIG_CGROUP_WRITEBACK INIT_LIST_HEAD(&memcg->cgwb_list); for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) memcg->cgwb_frn[i].done = __WB_COMPLETION_INIT(&memcg_cgwb_frn_waitq); #endif #ifdef CONFIG_TRANSPARENT_HUGEPAGE spin_lock_init(&memcg->deferred_split_queue.split_queue_lock); INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue); memcg->deferred_split_queue.split_queue_len = 0; #endif idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); return memcg; fail: mem_cgroup_id_remove(memcg); __mem_cgroup_free(memcg); return ERR_PTR(error); } static struct cgroup_subsys_state * __ref mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) { struct mem_cgroup *parent = mem_cgroup_from_css(parent_css); struct mem_cgroup *memcg; long error = -ENOMEM; memcg = mem_cgroup_alloc(); if (IS_ERR(memcg)) return ERR_CAST(memcg); page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); if (parent) { memcg->swappiness = mem_cgroup_swappiness(parent); memcg->oom_kill_disable = parent->oom_kill_disable; } if (parent && parent->use_hierarchy) { memcg->use_hierarchy = true; page_counter_init(&memcg->memory, &parent->memory); page_counter_init(&memcg->swap, &parent->swap); page_counter_init(&memcg->memsw, &parent->memsw); page_counter_init(&memcg->kmem, &parent->kmem); page_counter_init(&memcg->tcpmem, &parent->tcpmem); } else { page_counter_init(&memcg->memory, NULL); page_counter_init(&memcg->swap, NULL); page_counter_init(&memcg->memsw, NULL); page_counter_init(&memcg->kmem, NULL); page_counter_init(&memcg->tcpmem, 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) memory_cgrp_subsys.broken_hierarchy = true; } /* The following stuff does not apply to the root */ if (!parent) { #ifdef CONFIG_MEMCG_KMEM INIT_LIST_HEAD(&memcg->kmem_caches); #endif root_mem_cgroup = memcg; return &memcg->css; } error = memcg_online_kmem(memcg); if (error) goto fail; if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket) static_branch_inc(&memcg_sockets_enabled_key); return &memcg->css; fail: mem_cgroup_id_remove(memcg); 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); /* * A memcg must be visible for memcg_expand_shrinker_maps() * by the time the maps are allocated. So, we allocate maps * here, when for_each_mem_cgroup() can't skip it. */ if (memcg_alloc_shrinker_maps(memcg)) { mem_cgroup_id_remove(memcg); return -ENOMEM; } /* Online state pins memcg ID, memcg ID pins CSS */ refcount_set(&memcg->id.ref, 1); css_get(css); return 0; } static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_event *event, *tmp; /* * Unregister events and notify userspace. * Notify userspace about cgroup removing only after rmdir of cgroup * directory to avoid race between userspace and kernelspace. */ spin_lock(&memcg->event_list_lock); list_for_each_entry_safe(event, tmp, &memcg->event_list, list) { list_del_init(&event->list); schedule_work(&event->remove); } spin_unlock(&memcg->event_list_lock); page_counter_set_min(&memcg->memory, 0); page_counter_set_low(&memcg->memory, 0); memcg_offline_kmem(memcg); wb_memcg_offline(memcg); drain_all_stock(memcg); mem_cgroup_id_put(memcg); } static void mem_cgroup_css_released(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); invalidate_reclaim_iterators(memcg); } static void mem_cgroup_css_free(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); int __maybe_unused i; #ifdef CONFIG_CGROUP_WRITEBACK for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) wb_wait_for_completion(&memcg->cgwb_frn[i].done); #endif if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket) static_branch_dec(&memcg_sockets_enabled_key); if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_active) static_branch_dec(&memcg_sockets_enabled_key); vmpressure_cleanup(&memcg->vmpressure); cancel_work_sync(&memcg->high_work); mem_cgroup_remove_from_trees(memcg); memcg_free_shrinker_maps(memcg); memcg_free_kmem(memcg); mem_cgroup_free(memcg); } /** * mem_cgroup_css_reset - reset the states of a mem_cgroup * @css: the target css * * Reset the states of the mem_cgroup associated with @css. This is * invoked when the userland requests disabling on the default hierarchy * but the memcg is pinned through dependency. The memcg should stop * applying policies and should revert to the vanilla state as it may be * made visible again. * * The current implementation only resets the essential configurations. * This needs to be expanded to cover all the visible parts. */ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX); page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX); page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX); page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX); page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX); page_counter_set_min(&memcg->memory, 0); page_counter_set_low(&memcg->memory, 0); page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); memcg_wb_domain_size_changed(memcg); } #ifdef CONFIG_MMU /* Handlers for move charge at task migration. */ static int mem_cgroup_do_precharge(unsigned long count) { int ret; /* Try a single bulk charge without reclaim first, kswapd may wake */ ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count); if (!ret) { mc.precharge += count; return ret; } /* Try charges one by one with reclaim, but do not retry */ while (count--) { ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1); if (ret) return ret; mc.precharge++; cond_resched(); } return 0; } union mc_target { struct page *page; swp_entry_t ent; }; enum mc_target_type { MC_TARGET_NONE = 0, MC_TARGET_PAGE, MC_TARGET_SWAP, MC_TARGET_DEVICE, }; 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)) { if (!(mc.flags & MOVE_ANON)) return NULL; } else { if (!(mc.flags & MOVE_FILE)) return NULL; } if (!get_page_unless_zero(page)) return NULL; return page; } #if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE) static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, pte_t ptent, swp_entry_t *entry) { struct page *page = NULL; swp_entry_t ent = pte_to_swp_entry(ptent); if (!(mc.flags & MOVE_ANON) || non_swap_entry(ent)) return NULL; /* * Handle MEMORY_DEVICE_PRIVATE which are ZONE_DEVICE page belonging to * a device and because they are not accessible by CPU they are store * as special swap entry in the CPU page table. */ if (is_device_private_entry(ent)) { page = device_private_entry_to_page(ent); /* * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have * a refcount of 1 when free (unlike normal page) */ if (!page_ref_add_unless(page, 1, 1)) return NULL; return page; } /* * 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), swp_offset(ent)); if (do_memsw_account()) entry->val = ent.val; return page; } #else static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, 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 (!(mc.flags & MOVE_FILE)) return NULL; mapping = vma->vm_file->f_mapping; pgoff = linear_page_index(vma, addr); /* page is moved even if it's not RSS of this task(page-faulted). */ #ifdef CONFIG_SWAP /* shmem/tmpfs may report page out on swap: account for that too. */ if (shmem_mapping(mapping)) { page = find_get_entry(mapping, pgoff); if (xa_is_value(page)) { swp_entry_t swp = radix_to_swp_entry(page); if (do_memsw_account()) *entry = swp; page = find_get_page(swap_address_space(swp), swp_offset(swp)); } } else page = find_get_page(mapping, pgoff); #else page = find_get_page(mapping, pgoff); #endif return page; } /** * mem_cgroup_move_account - move account of the page * @page: the page * @compound: charge the page as compound or small page * @from: mem_cgroup which the page is moved from. * @to: mem_cgroup which the page is moved to. @from != @to. * * The caller must make sure the page is not on LRU (isolate_page() is useful.) * * 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, bool compound, struct mem_cgroup *from, struct mem_cgroup *to) { struct lruvec *from_vec, *to_vec; struct pglist_data *pgdat; unsigned long flags; unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; int ret; bool anon; VM_BUG_ON(from == to); VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON(compound && !PageTransHuge(page)); /* * Prevent mem_cgroup_migrate() from looking at * page->mem_cgroup of its source page while we change it. */ ret = -EBUSY; if (!trylock_page(page)) goto out; ret = -EINVAL; if (page->mem_cgroup != from) goto out_unlock; anon = PageAnon(page); pgdat = page_pgdat(page); from_vec = mem_cgroup_lruvec(from, pgdat); to_vec = mem_cgroup_lruvec(to, pgdat); spin_lock_irqsave(&from->move_lock, flags); if (!anon && page_mapped(page)) { __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages); } /* * move_lock grabbed above and caller set from->moving_account, so * mod_memcg_page_state will serialize updates to PageDirty. * So mapping should be stable for dirty pages. */ if (!anon && PageDirty(page)) { struct address_space *mapping = page_mapping(page); if (mapping_cap_account_dirty(mapping)) { __mod_lruvec_state(from_vec, NR_FILE_DIRTY, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_DIRTY, nr_pages); } } if (PageWriteback(page)) { __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages); __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages); } /* * It is safe to change page->mem_cgroup here because the page * is referenced, charged, and isolated - we can't race with * uncharging, charging, migration, or LRU putback. */ /* caller should have done css_get */ page->mem_cgroup = to; spin_unlock_irqrestore(&from->move_lock, flags); ret = 0; local_irq_disable(); mem_cgroup_charge_statistics(to, page, compound, nr_pages); memcg_check_events(to, page); mem_cgroup_charge_statistics(from, page, compound, -nr_pages); memcg_check_events(from, page); local_irq_enable(); out_unlock: unlock_page(page); out: 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. * 3(MC_TARGET_DEVICE): like MC_TARGET_PAGE but page is MEMORY_DEVICE_PRIVATE * (so ZONE_DEVICE page and thus not on the lru). * For now we such page is charge like a regular page would be as for all * intent and purposes it is just special memory taking the place of a * regular page. * * See Documentations/vm/hmm.txt and include/linux/hmm.h * * Called with pte lock held. */ 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; 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, ptent, &ent); else if (pte_none(ptent)) page = mc_handle_file_pte(vma, addr, ptent, &ent); if (!page && !ent.val) return ret; if (page) { /* * Do only loose check w/o serialization. * mem_cgroup_move_account() checks the page is valid or * not under LRU exclusion. */ if (page->mem_cgroup == mc.from) { ret = MC_TARGET_PAGE; if (is_device_private_page(page)) ret = MC_TARGET_DEVICE; 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. * But we cannot move a tail-page in a THP. */ if (ent.val && !ret && (!page || !PageTransCompound(page)) && 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 PMD mapped 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; enum mc_target_type ret = MC_TARGET_NONE; if (unlikely(is_swap_pmd(pmd))) { VM_BUG_ON(thp_migration_supported() && !is_pmd_migration_entry(pmd)); return ret; } page = pmd_page(pmd); VM_BUG_ON_PAGE(!page || !PageHead(page), page); if (!(mc.flags & MOVE_ANON)) return ret; if (page->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->vma; pte_t *pte; spinlock_t *ptl; ptl = pmd_trans_huge_lock(pmd, vma); if (ptl) { /* * Note their can not be MC_TARGET_DEVICE for now as we do not * support transparent huge page with MEMORY_DEVICE_PRIVATE but * this might change. */ if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) mc.precharge += HPAGE_PMD_NR; spin_unlock(ptl); 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 const struct mm_walk_ops precharge_walk_ops = { .pmd_entry = mem_cgroup_count_precharge_pte_range, }; static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) { unsigned long precharge; down_read(&mm->mmap_sem); walk_page_range(mm, 0, mm->highest_vm_end, &precharge_walk_ops, NULL); 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; /* we must uncharge all the leftover precharges from mc.to */ if (mc.precharge) { 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) { 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)) page_counter_uncharge(&mc.from->memsw, mc.moved_swap); mem_cgroup_id_put_many(mc.from, mc.moved_swap); /* * we charged both to->memory and to->memsw, so we * should uncharge to->memory. */ if (!mem_cgroup_is_root(mc.to)) page_counter_uncharge(&mc.to->memory, mc.moved_swap); mem_cgroup_id_get_many(mc.to, mc.moved_swap); css_put_many(&mc.to->css, mc.moved_swap); 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 mm_struct *mm = mc.mm; /* * 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; mc.mm = NULL; spin_unlock(&mc.lock); mmput(mm); } static int mem_cgroup_can_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */ struct mem_cgroup *from; struct task_struct *leader, *p; struct mm_struct *mm; unsigned long move_flags; int ret = 0; /* charge immigration isn't supported on the default hierarchy */ if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; /* * Multi-process migrations only happen on the default hierarchy * where charge immigration is not used. Perform charge * immigration if @tset contains a leader and whine if there are * multiple. */ p = NULL; cgroup_taskset_for_each_leader(leader, css, tset) { WARN_ON_ONCE(p); p = leader; memcg = mem_cgroup_from_css(css); } if (!p) return 0; /* * 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_flags = READ_ONCE(memcg->move_charge_at_immigrate); if (!move_flags) return 0; 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); spin_lock(&mc.lock); mc.mm = mm; mc.from = from; mc.to = memcg; mc.flags = move_flags; spin_unlock(&mc.lock); /* We set mc.moving_task later */ ret = mem_cgroup_precharge_mc(mm); if (ret) mem_cgroup_clear_mc(); } else { mmput(mm); } return ret; } static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) { if (mc.to) 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->vma; pte_t *pte; spinlock_t *ptl; enum mc_target_type target_type; union mc_target target; struct page *page; ptl = pmd_trans_huge_lock(pmd, vma); if (ptl) { if (mc.precharge < HPAGE_PMD_NR) { spin_unlock(ptl); 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)) { if (!mem_cgroup_move_account(page, true, mc.from, mc.to)) { mc.precharge -= HPAGE_PMD_NR; mc.moved_charge += HPAGE_PMD_NR; } putback_lru_page(page); } put_page(page); } else if (target_type == MC_TARGET_DEVICE) { page = target.page; if (!mem_cgroup_move_account(page, true, mc.from, mc.to)) { mc.precharge -= HPAGE_PMD_NR; mc.moved_charge += HPAGE_PMD_NR; } put_page(page); } spin_unlock(ptl); 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++); bool device = false; swp_entry_t ent; if (!mc.precharge) break; switch (get_mctgt_type(vma, addr, ptent, &target)) { case MC_TARGET_DEVICE: device = true; fallthrough; case MC_TARGET_PAGE: page = target.page; /* * We can have a part of the split pmd here. Moving it * can be done but it would be too convoluted so simply * ignore such a partial THP and keep it in original * memcg. There should be somebody mapping the head. */ if (PageTransCompound(page)) goto put; if (!device && isolate_lru_page(page)) goto put; if (!mem_cgroup_move_account(page, false, mc.from, mc.to)) { mc.precharge--; /* we uncharge from mc.from later. */ mc.moved_charge++; } if (!device) 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 const struct mm_walk_ops charge_walk_ops = { .pmd_entry = mem_cgroup_move_charge_pte_range, }; static void mem_cgroup_move_charge(void) { lru_add_drain_all(); /* * Signal lock_page_memcg() to take the memcg's move_lock * while we're moving its pages to another memcg. Then wait * for already started RCU-only updates to finish. */ atomic_inc(&mc.from->moving_account); synchronize_rcu(); retry: if (unlikely(!down_read_trylock(&mc.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; } /* * When we have consumed all precharges and failed in doing * additional charge, the page walk just aborts. */ walk_page_range(mc.mm, 0, mc.mm->highest_vm_end, &charge_walk_ops, NULL); up_read(&mc.mm->mmap_sem); atomic_dec(&mc.from->moving_account); } static void mem_cgroup_move_task(void) { if (mc.to) { mem_cgroup_move_charge(); mem_cgroup_clear_mc(); } } #else /* !CONFIG_MMU */ static int mem_cgroup_can_attach(struct cgroup_taskset *tset) { return 0; } static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) { } static void mem_cgroup_move_task(void) { } #endif /* * Cgroup retains root cgroups across [un]mount cycles making it necessary * to verify whether we're attached to the default hierarchy on each mount * attempt. */ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) { /* * use_hierarchy is forced on the default hierarchy. cgroup core * guarantees that @root doesn't have any children, so turning it * on for the root memcg is enough. */ if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) root_mem_cgroup->use_hierarchy = true; else root_mem_cgroup->use_hierarchy = false; } static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value) { if (value == PAGE_COUNTER_MAX) seq_puts(m, "max\n"); else seq_printf(m, "%llu\n", (u64)value * PAGE_SIZE); return 0; } static u64 memory_current_read(struct cgroup_subsys_state *css, struct cftype *cft) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE; } static int memory_min_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->memory.min)); } static ssize_t memory_min_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned long min; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &min); if (err) return err; page_counter_set_min(&memcg->memory, min); return nbytes; } static int memory_low_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->memory.low)); } static ssize_t memory_low_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned long low; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &low); if (err) return err; page_counter_set_low(&memcg->memory, low); return nbytes; } static int memory_high_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->memory.high)); } static ssize_t memory_high_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; bool drained = false; unsigned long high; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &high); if (err) return err; page_counter_set_high(&memcg->memory, high); for (;;) { unsigned long nr_pages = page_counter_read(&memcg->memory); unsigned long reclaimed; if (nr_pages <= high) break; if (signal_pending(current)) break; if (!drained) { drain_all_stock(memcg); drained = true; continue; } reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high, GFP_KERNEL, true); if (!reclaimed && !nr_retries--) break; } return nbytes; } static int memory_max_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->memory.max)); } static ssize_t memory_max_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES; bool drained = false; unsigned long max; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &max); if (err) return err; xchg(&memcg->memory.max, max); for (;;) { unsigned long nr_pages = page_counter_read(&memcg->memory); if (nr_pages <= max) break; if (signal_pending(current)) break; if (!drained) { drain_all_stock(memcg); drained = true; continue; } if (nr_reclaims) { if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max, GFP_KERNEL, true)) nr_reclaims--; continue; } memcg_memory_event(memcg, MEMCG_OOM); if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0)) break; } memcg_wb_domain_size_changed(memcg); return nbytes; } static void __memory_events_show(struct seq_file *m, atomic_long_t *events) { seq_printf(m, "low %lu\n", atomic_long_read(&events[MEMCG_LOW])); seq_printf(m, "high %lu\n", atomic_long_read(&events[MEMCG_HIGH])); seq_printf(m, "max %lu\n", atomic_long_read(&events[MEMCG_MAX])); seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM])); seq_printf(m, "oom_kill %lu\n", atomic_long_read(&events[MEMCG_OOM_KILL])); } static int memory_events_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); __memory_events_show(m, memcg->memory_events); return 0; } static int memory_events_local_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); __memory_events_show(m, memcg->memory_events_local); return 0; } static int memory_stat_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); char *buf; buf = memory_stat_format(memcg); if (!buf) return -ENOMEM; seq_puts(m, buf); kfree(buf); return 0; } static int memory_oom_group_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); seq_printf(m, "%d\n", memcg->oom_group); return 0; } static ssize_t memory_oom_group_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); int ret, oom_group; buf = strstrip(buf); if (!buf) return -EINVAL; ret = kstrtoint(buf, 0, &oom_group); if (ret) return ret; if (oom_group != 0 && oom_group != 1) return -EINVAL; memcg->oom_group = oom_group; return nbytes; } static struct cftype memory_files[] = { { .name = "current", .flags = CFTYPE_NOT_ON_ROOT, .read_u64 = memory_current_read, }, { .name = "min", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = memory_min_show, .write = memory_min_write, }, { .name = "low", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = memory_low_show, .write = memory_low_write, }, { .name = "high", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = memory_high_show, .write = memory_high_write, }, { .name = "max", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = memory_max_show, .write = memory_max_write, }, { .name = "events", .flags = CFTYPE_NOT_ON_ROOT, .file_offset = offsetof(struct mem_cgroup, events_file), .seq_show = memory_events_show, }, { .name = "events.local", .flags = CFTYPE_NOT_ON_ROOT, .file_offset = offsetof(struct mem_cgroup, events_local_file), .seq_show = memory_events_local_show, }, { .name = "stat", .seq_show = memory_stat_show, }, { .name = "oom.group", .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE, .seq_show = memory_oom_group_show, .write = memory_oom_group_write, }, { } /* terminate */ }; struct cgroup_subsys memory_cgrp_subsys = { .css_alloc = mem_cgroup_css_alloc, .css_online = mem_cgroup_css_online, .css_offline = mem_cgroup_css_offline, .css_released = mem_cgroup_css_released, .css_free = mem_cgroup_css_free, .css_reset = mem_cgroup_css_reset, .can_attach = mem_cgroup_can_attach, .cancel_attach = mem_cgroup_cancel_attach, .post_attach = mem_cgroup_move_task, .bind = mem_cgroup_bind, .dfl_cftypes = memory_files, .legacy_cftypes = mem_cgroup_legacy_files, .early_init = 0, }; /* * This function calculates an individual cgroup's effective * protection which is derived from its own memory.min/low, its * parent's and siblings' settings, as well as the actual memory * distribution in the tree. * * The following rules apply to the effective protection values: * * 1. At the first level of reclaim, effective protection is equal to * the declared protection in memory.min and memory.low. * * 2. To enable safe delegation of the protection configuration, at * subsequent levels the effective protection is capped to the * parent's effective protection. * * 3. To make complex and dynamic subtrees easier to configure, the * user is allowed to overcommit the declared protection at a given * level. If that is the case, the parent's effective protection is * distributed to the children in proportion to how much protection * they have declared and how much of it they are utilizing. * * This makes distribution proportional, but also work-conserving: * if one cgroup claims much more protection than it uses memory, * the unused remainder is available to its siblings. * * 4. Conversely, when the declared protection is undercommitted at a * given level, the distribution of the larger parental protection * budget is NOT proportional. A cgroup's protection from a sibling * is capped to its own memory.min/low setting. * * 5. However, to allow protecting recursive subtrees from each other * without having to declare each individual cgroup's fixed share * of the ancestor's claim to protection, any unutilized - * "floating" - protection from up the tree is distributed in * proportion to each cgroup's *usage*. This makes the protection * neutral wrt sibling cgroups and lets them compete freely over * the shared parental protection budget, but it protects the * subtree as a whole from neighboring subtrees. * * Note that 4. and 5. are not in conflict: 4. is about protecting * against immediate siblings whereas 5. is about protecting against * neighboring subtrees. */ static unsigned long effective_protection(unsigned long usage, unsigned long parent_usage, unsigned long setting, unsigned long parent_effective, unsigned long siblings_protected) { unsigned long protected; unsigned long ep; protected = min(usage, setting); /* * If all cgroups at this level combined claim and use more * protection then what the parent affords them, distribute * shares in proportion to utilization. * * We are using actual utilization rather than the statically * claimed protection in order to be work-conserving: claimed * but unused protection is available to siblings that would * otherwise get a smaller chunk than what they claimed. */ if (siblings_protected > parent_effective) return protected * parent_effective / siblings_protected; /* * Ok, utilized protection of all children is within what the * parent affords them, so we know whatever this child claims * and utilizes is effectively protected. * * If there is unprotected usage beyond this value, reclaim * will apply pressure in proportion to that amount. * * If there is unutilized protection, the cgroup will be fully * shielded from reclaim, but we do return a smaller value for * protection than what the group could enjoy in theory. This * is okay. With the overcommit distribution above, effective * protection is always dependent on how memory is actually * consumed among the siblings anyway. */ ep = protected; /* * If the children aren't claiming (all of) the protection * afforded to them by the parent, distribute the remainder in * proportion to the (unprotected) memory of each cgroup. That * way, cgroups that aren't explicitly prioritized wrt each * other compete freely over the allowance, but they are * collectively protected from neighboring trees. * * We're using unprotected memory for the weight so that if * some cgroups DO claim explicit protection, we don't protect * the same bytes twice. */ if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)) return ep; if (parent_effective > siblings_protected && usage > protected) { unsigned long unclaimed; unclaimed = parent_effective - siblings_protected; unclaimed *= usage - protected; unclaimed /= parent_usage - siblings_protected; ep += unclaimed; } return ep; } /** * mem_cgroup_protected - check if memory consumption is in the normal range * @root: the top ancestor of the sub-tree being checked * @memcg: the memory cgroup to check * * WARNING: This function is not stateless! It can only be used as part * of a top-down tree iteration, not for isolated queries. * * Returns one of the following: * MEMCG_PROT_NONE: cgroup memory is not protected * MEMCG_PROT_LOW: cgroup memory is protected as long there is * an unprotected supply of reclaimable memory from other cgroups. * MEMCG_PROT_MIN: cgroup memory is protected */ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, struct mem_cgroup *memcg) { unsigned long usage, parent_usage; struct mem_cgroup *parent; if (mem_cgroup_disabled()) return MEMCG_PROT_NONE; if (!root) root = root_mem_cgroup; if (memcg == root) return MEMCG_PROT_NONE; usage = page_counter_read(&memcg->memory); if (!usage) return MEMCG_PROT_NONE; parent = parent_mem_cgroup(memcg); /* No parent means a non-hierarchical mode on v1 memcg */ if (!parent) return MEMCG_PROT_NONE; if (parent == root) { memcg->memory.emin = READ_ONCE(memcg->memory.min); memcg->memory.elow = memcg->memory.low; goto out; } parent_usage = page_counter_read(&parent->memory); WRITE_ONCE(memcg->memory.emin, effective_protection(usage, parent_usage, READ_ONCE(memcg->memory.min), READ_ONCE(parent->memory.emin), atomic_long_read(&parent->memory.children_min_usage))); WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage, memcg->memory.low, READ_ONCE(parent->memory.elow), atomic_long_read(&parent->memory.children_low_usage))); out: if (usage <= memcg->memory.emin) return MEMCG_PROT_MIN; else if (usage <= memcg->memory.elow) return MEMCG_PROT_LOW; else return MEMCG_PROT_NONE; } /** * mem_cgroup_try_charge - try charging a page * @page: page to charge * @mm: mm context of the victim * @gfp_mask: reclaim mode * @memcgp: charged memcg return * @compound: charge the page as compound or small page * * Try to charge @page to the memcg that @mm belongs to, reclaiming * pages according to @gfp_mask if necessary. * * Returns 0 on success, with *@memcgp pointing to the charged memcg. * Otherwise, an error code is returned. * * After page->mapping has been set up, the caller must finalize the * charge with mem_cgroup_commit_charge(). Or abort the transaction * with mem_cgroup_cancel_charge() in case page instantiation fails. */ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, struct mem_cgroup **memcgp, bool compound) { struct mem_cgroup *memcg = NULL; unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; int ret = 0; if (mem_cgroup_disabled()) goto out; if (PageSwapCache(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. */ VM_BUG_ON_PAGE(!PageLocked(page), page); if (compound_head(page)->mem_cgroup) goto out; if (do_swap_account) { swp_entry_t ent = { .val = page_private(page), }; unsigned short id = lookup_swap_cgroup_id(ent); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg && !css_tryget_online(&memcg->css)) memcg = NULL; rcu_read_unlock(); } } if (!memcg) memcg = get_mem_cgroup_from_mm(mm); ret = try_charge(memcg, gfp_mask, nr_pages); css_put(&memcg->css); out: *memcgp = memcg; return ret; } int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, struct mem_cgroup **memcgp, bool compound) { struct mem_cgroup *memcg; int ret; ret = mem_cgroup_try_charge(page, mm, gfp_mask, memcgp, compound); memcg = *memcgp; mem_cgroup_throttle_swaprate(memcg, page_to_nid(page), gfp_mask); return ret; } /** * mem_cgroup_commit_charge - commit a page charge * @page: page to charge * @memcg: memcg to charge the page to * @lrucare: page might be on LRU already * @compound: charge the page as compound or small page * * Finalize a charge transaction started by mem_cgroup_try_charge(), * after page->mapping has been set up. This must happen atomically * as part of the page instantiation, i.e. under the page table lock * for anonymous pages, under the page lock for page and swap cache. * * In addition, the page must not be on the LRU during the commit, to * prevent racing with task migration. If it might be, use @lrucare. * * Use mem_cgroup_cancel_charge() to cancel the transaction instead. */ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg, bool lrucare, bool compound) { unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; VM_BUG_ON_PAGE(!page->mapping, page); VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page); if (mem_cgroup_disabled()) return; /* * Swap faults will attempt to charge the same page multiple * times. But reuse_swap_page() might have removed the page * from swapcache already, so we can't check PageSwapCache(). */ if (!memcg) return; commit_charge(page, memcg, lrucare); local_irq_disable(); mem_cgroup_charge_statistics(memcg, page, compound, nr_pages); memcg_check_events(memcg, page); local_irq_enable(); if (do_memsw_account() && PageSwapCache(page)) { swp_entry_t entry = { .val = page_private(page) }; /* * The swap entry might not get freed for a long time, * let's not wait for it. The page already received a * memory+swap charge, drop the swap entry duplicate. */ mem_cgroup_uncharge_swap(entry, nr_pages); } } /** * mem_cgroup_cancel_charge - cancel a page charge * @page: page to charge * @memcg: memcg to charge the page to * @compound: charge the page as compound or small page * * Cancel a charge transaction started by mem_cgroup_try_charge(). */ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg, bool compound) { unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; if (mem_cgroup_disabled()) return; /* * Swap faults will attempt to charge the same page multiple * times. But reuse_swap_page() might have removed the page * from swapcache already, so we can't check PageSwapCache(). */ if (!memcg) return; cancel_charge(memcg, nr_pages); } struct uncharge_gather { struct mem_cgroup *memcg; unsigned long pgpgout; unsigned long nr_anon; unsigned long nr_file; unsigned long nr_kmem; unsigned long nr_huge; unsigned long nr_shmem; struct page *dummy_page; }; static inline void uncharge_gather_clear(struct uncharge_gather *ug) { memset(ug, 0, sizeof(*ug)); } static void uncharge_batch(const struct uncharge_gather *ug) { unsigned long nr_pages = ug->nr_anon + ug->nr_file + ug->nr_kmem; unsigned long flags; if (!mem_cgroup_is_root(ug->memcg)) { page_counter_uncharge(&ug->memcg->memory, nr_pages); if (do_memsw_account()) page_counter_uncharge(&ug->memcg->memsw, nr_pages); if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && ug->nr_kmem) page_counter_uncharge(&ug->memcg->kmem, ug->nr_kmem); memcg_oom_recover(ug->memcg); } local_irq_save(flags); __mod_memcg_state(ug->memcg, MEMCG_RSS, -ug->nr_anon); __mod_memcg_state(ug->memcg, MEMCG_CACHE, -ug->nr_file); __mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge); __mod_memcg_state(ug->memcg, NR_SHMEM, -ug->nr_shmem); __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout); __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, nr_pages); memcg_check_events(ug->memcg, ug->dummy_page); local_irq_restore(flags); if (!mem_cgroup_is_root(ug->memcg)) css_put_many(&ug->memcg->css, nr_pages); } static void uncharge_page(struct page *page, struct uncharge_gather *ug) { VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) && !PageHWPoison(page) , page); if (!page->mem_cgroup) return; /* * Nobody should be changing or seriously looking at * page->mem_cgroup at this point, we have fully * exclusive access to the page. */ if (ug->memcg != page->mem_cgroup) { if (ug->memcg) { uncharge_batch(ug); uncharge_gather_clear(ug); } ug->memcg = page->mem_cgroup; } if (!PageKmemcg(page)) { unsigned int nr_pages = 1; if (PageTransHuge(page)) { nr_pages = compound_nr(page); ug->nr_huge += nr_pages; } if (PageAnon(page)) ug->nr_anon += nr_pages; else { ug->nr_file += nr_pages; if (PageSwapBacked(page)) ug->nr_shmem += nr_pages; } ug->pgpgout++; } else { ug->nr_kmem += compound_nr(page); __ClearPageKmemcg(page); } ug->dummy_page = page; page->mem_cgroup = NULL; } static void uncharge_list(struct list_head *page_list) { struct uncharge_gather ug; struct list_head *next; uncharge_gather_clear(&ug); /* * Note that the list can be a single page->lru; hence the * do-while loop instead of a simple list_for_each_entry(). */ next = page_list->next; do { struct page *page; page = list_entry(next, struct page, lru); next = page->lru.next; uncharge_page(page, &ug); } while (next != page_list); if (ug.memcg) uncharge_batch(&ug); } /** * mem_cgroup_uncharge - uncharge a page * @page: page to uncharge * * Uncharge a page previously charged with mem_cgroup_try_charge() and * mem_cgroup_commit_charge(). */ void mem_cgroup_uncharge(struct page *page) { struct uncharge_gather ug; if (mem_cgroup_disabled()) return; /* Don't touch page->lru of any random page, pre-check: */ if (!page->mem_cgroup) return; uncharge_gather_clear(&ug); uncharge_page(page, &ug); uncharge_batch(&ug); } /** * mem_cgroup_uncharge_list - uncharge a list of page * @page_list: list of pages to uncharge * * Uncharge a list of pages previously charged with * mem_cgroup_try_charge() and mem_cgroup_commit_charge(). */ void mem_cgroup_uncharge_list(struct list_head *page_list) { if (mem_cgroup_disabled()) return; if (!list_empty(page_list)) uncharge_list(page_list); } /** * mem_cgroup_migrate - charge a page's replacement * @oldpage: currently circulating page * @newpage: replacement page * * Charge @newpage as a replacement page for @oldpage. @oldpage will * be uncharged upon free. * * Both pages must be locked, @newpage->mapping must be set up. */ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) { struct mem_cgroup *memcg; unsigned int nr_pages; unsigned long flags; VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage); VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage); VM_BUG_ON_PAGE(PageTransHuge(oldpage) != PageTransHuge(newpage), newpage); if (mem_cgroup_disabled()) return; /* Page cache replacement: new page already charged? */ if (newpage->mem_cgroup) return; /* Swapcache readahead pages can get replaced before being charged */ memcg = oldpage->mem_cgroup; if (!memcg) return; /* Force-charge the new page. The old one will be freed soon */ nr_pages = hpage_nr_pages(newpage); page_counter_charge(&memcg->memory, nr_pages); if (do_memsw_account()) page_counter_charge(&memcg->memsw, nr_pages); css_get_many(&memcg->css, nr_pages); commit_charge(newpage, memcg, false); local_irq_save(flags); mem_cgroup_charge_statistics(memcg, newpage, PageTransHuge(newpage), nr_pages); memcg_check_events(memcg, newpage); local_irq_restore(flags); } DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key); EXPORT_SYMBOL(memcg_sockets_enabled_key); void mem_cgroup_sk_alloc(struct sock *sk) { struct mem_cgroup *memcg; if (!mem_cgroup_sockets_enabled) return; /* Do not associate the sock with unrelated interrupted task's memcg. */ if (in_interrupt()) return; rcu_read_lock(); memcg = mem_cgroup_from_task(current); if (memcg == root_mem_cgroup) goto out; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active) goto out; if (css_tryget(&memcg->css)) sk->sk_memcg = memcg; out: rcu_read_unlock(); } void mem_cgroup_sk_free(struct sock *sk) { if (sk->sk_memcg) css_put(&sk->sk_memcg->css); } /** * mem_cgroup_charge_skmem - charge socket memory * @memcg: memcg to charge * @nr_pages: number of pages to charge * * Charges @nr_pages to @memcg. Returns %true if the charge fit within * @memcg's configured limit, %false if the charge had to be forced. */ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages) { gfp_t gfp_mask = GFP_KERNEL; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) { struct page_counter *fail; if (page_counter_try_charge(&memcg->tcpmem, nr_pages, &fail)) { memcg->tcpmem_pressure = 0; return true; } page_counter_charge(&memcg->tcpmem, nr_pages); memcg->tcpmem_pressure = 1; return false; } /* Don't block in the packet receive path */ if (in_softirq()) gfp_mask = GFP_NOWAIT; mod_memcg_state(memcg, MEMCG_SOCK, nr_pages); if (try_charge(memcg, gfp_mask, nr_pages) == 0) return true; try_charge(memcg, gfp_mask|__GFP_NOFAIL, nr_pages); return false; } /** * mem_cgroup_uncharge_skmem - uncharge socket memory * @memcg: memcg to uncharge * @nr_pages: number of pages to uncharge */ void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages) { if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) { page_counter_uncharge(&memcg->tcpmem, nr_pages); return; } mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages); refill_stock(memcg, nr_pages); } static int __init cgroup_memory(char *s) { char *token; while ((token = strsep(&s, ",")) != NULL) { if (!*token) continue; if (!strcmp(token, "nosocket")) cgroup_memory_nosocket = true; if (!strcmp(token, "nokmem")) cgroup_memory_nokmem = true; } return 0; } __setup("cgroup.memory=", cgroup_memory); /* * subsys_initcall() for memory controller. * * Some parts like memcg_hotplug_cpu_dead() 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) { int cpu, node; #ifdef CONFIG_MEMCG_KMEM /* * Kmem cache creation is mostly done with the slab_mutex held, * so use a workqueue with limited concurrency to avoid stalling * all worker threads in case lots of cgroups are created and * destroyed simultaneously. */ memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1); BUG_ON(!memcg_kmem_cache_wq); #endif cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL, memcg_hotplug_cpu_dead); for_each_possible_cpu(cpu) INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work, drain_local_stock); for_each_node(node) { struct mem_cgroup_tree_per_node *rtpn; rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, node_online(node) ? node : NUMA_NO_NODE); rtpn->rb_root = RB_ROOT; rtpn->rb_rightmost = NULL; spin_lock_init(&rtpn->lock); soft_limit_tree.rb_tree_per_node[node] = rtpn; } return 0; } subsys_initcall(mem_cgroup_init); #ifdef CONFIG_MEMCG_SWAP static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) { while (!refcount_inc_not_zero(&memcg->id.ref)) { /* * The root cgroup cannot be destroyed, so it's refcount must * always be >= 1. */ if (WARN_ON_ONCE(memcg == root_mem_cgroup)) { VM_BUG_ON(1); break; } memcg = parent_mem_cgroup(memcg); if (!memcg) memcg = root_mem_cgroup; } return memcg; } /** * mem_cgroup_swapout - transfer a memsw charge to swap * @page: page whose memsw charge to transfer * @entry: swap entry to move the charge to * * Transfer the memsw charge of @page to @entry. */ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) { struct mem_cgroup *memcg, *swap_memcg; unsigned int nr_entries; unsigned short oldid; VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); if (!do_memsw_account()) return; memcg = page->mem_cgroup; /* Readahead page, never charged */ if (!memcg) return; /* * In case the memcg owning these pages has been offlined and doesn't * have an ID allocated to it anymore, charge the closest online * ancestor for the swap instead and transfer the memory+swap charge. */ swap_memcg = mem_cgroup_id_get_online(memcg); nr_entries = hpage_nr_pages(page); /* Get references for the tail pages, too */ if (nr_entries > 1) mem_cgroup_id_get_many(swap_memcg, nr_entries - 1); oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg), nr_entries); VM_BUG_ON_PAGE(oldid, page); mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries); page->mem_cgroup = NULL; if (!mem_cgroup_is_root(memcg)) page_counter_uncharge(&memcg->memory, nr_entries); if (memcg != swap_memcg) { if (!mem_cgroup_is_root(swap_memcg)) page_counter_charge(&swap_memcg->memsw, nr_entries); page_counter_uncharge(&memcg->memsw, nr_entries); } /* * Interrupts should be disabled here because the caller holds the * i_pages lock which is taken with interrupts-off. It is * important here to have the interrupts disabled because it is the * only synchronisation we have for updating the per-CPU variables. */ VM_BUG_ON(!irqs_disabled()); mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page), -nr_entries); memcg_check_events(memcg, page); if (!mem_cgroup_is_root(memcg)) css_put_many(&memcg->css, nr_entries); } /** * mem_cgroup_try_charge_swap - try charging swap space for a page * @page: page being added to swap * @entry: swap entry to charge * * Try to charge @page's memcg for the swap space at @entry. * * Returns 0 on success, -ENOMEM on failure. */ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) { unsigned int nr_pages = hpage_nr_pages(page); struct page_counter *counter; struct mem_cgroup *memcg; unsigned short oldid; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account) return 0; memcg = page->mem_cgroup; /* Readahead page, never charged */ if (!memcg) return 0; if (!entry.val) { memcg_memory_event(memcg, MEMCG_SWAP_FAIL); return 0; } memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) { memcg_memory_event(memcg, MEMCG_SWAP_MAX); memcg_memory_event(memcg, MEMCG_SWAP_FAIL); mem_cgroup_id_put(memcg); return -ENOMEM; } /* Get references for the tail pages, too */ if (nr_pages > 1) mem_cgroup_id_get_many(memcg, nr_pages - 1); oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages); VM_BUG_ON_PAGE(oldid, page); mod_memcg_state(memcg, MEMCG_SWAP, nr_pages); return 0; } /** * mem_cgroup_uncharge_swap - uncharge swap space * @entry: swap entry to uncharge * @nr_pages: the amount of swap space to uncharge */ void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) { struct mem_cgroup *memcg; unsigned short id; if (!do_swap_account) return; id = swap_cgroup_record(entry, 0, nr_pages); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg) { if (!mem_cgroup_is_root(memcg)) { if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) page_counter_uncharge(&memcg->swap, nr_pages); else page_counter_uncharge(&memcg->memsw, nr_pages); } mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages); mem_cgroup_id_put_many(memcg, nr_pages); } rcu_read_unlock(); } long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) { long nr_swap_pages = get_nr_swap_pages(); if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) return nr_swap_pages; for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) nr_swap_pages = min_t(long, nr_swap_pages, READ_ONCE(memcg->swap.max) - page_counter_read(&memcg->swap)); return nr_swap_pages; } bool mem_cgroup_swap_full(struct page *page) { struct mem_cgroup *memcg; VM_BUG_ON_PAGE(!PageLocked(page), page); if (vm_swap_full()) return true; if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) return false; memcg = page->mem_cgroup; if (!memcg) return false; for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) { unsigned long usage = page_counter_read(&memcg->swap); if (usage * 2 >= READ_ONCE(memcg->swap.high) || usage * 2 >= READ_ONCE(memcg->swap.max)) return true; } return false; } /* 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; #endif 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 u64 swap_current_read(struct cgroup_subsys_state *css, struct cftype *cft) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); return (u64)page_counter_read(&memcg->swap) * PAGE_SIZE; } static int swap_high_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->swap.high)); } static ssize_t swap_high_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned long high; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &high); if (err) return err; page_counter_set_high(&memcg->swap, high); return nbytes; } static int swap_max_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, READ_ONCE(mem_cgroup_from_seq(m)->swap.max)); } static ssize_t swap_max_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned long max; int err; buf = strstrip(buf); err = page_counter_memparse(buf, "max", &max); if (err) return err; xchg(&memcg->swap.max, max); return nbytes; } static int swap_events_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); seq_printf(m, "high %lu\n", atomic_long_read(&memcg->memory_events[MEMCG_SWAP_HIGH])); seq_printf(m, "max %lu\n", atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX])); seq_printf(m, "fail %lu\n", atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL])); return 0; } static struct cftype swap_files[] = { { .name = "swap.current", .flags = CFTYPE_NOT_ON_ROOT, .read_u64 = swap_current_read, }, { .name = "swap.high", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = swap_high_show, .write = swap_high_write, }, { .name = "swap.max", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = swap_max_show, .write = swap_max_write, }, { .name = "swap.events", .flags = CFTYPE_NOT_ON_ROOT, .file_offset = offsetof(struct mem_cgroup, swap_events_file), .seq_show = swap_events_show, }, { } /* terminate */ }; static struct cftype memsw_cgroup_files[] = { { .name = "memsw.usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), .read_u64 = mem_cgroup_read_u64, }, { .name = "memsw.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "memsw.limit_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), .write = mem_cgroup_write, .read_u64 = mem_cgroup_read_u64, }, { .name = "memsw.failcnt", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { }, /* terminate */ }; static int __init mem_cgroup_swap_init(void) { if (!mem_cgroup_disabled() && really_do_swap_account) { do_swap_account = 1; WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files)); WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_cgroup_files)); } return 0; } subsys_initcall(mem_cgroup_swap_init); #endif /* CONFIG_MEMCG_SWAP */