// 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 * * Per memcg lru locking * Copyright (C) 2020 Alibaba, Inc, Alex Shi */ #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 #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; /* Active memory cgroup to use from an interrupt context */ DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg); EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg); /* Socket memory accounting disabled? */ static bool cgroup_memory_nosocket __ro_after_init; /* Kernel memory accounting disabled? */ static bool cgroup_memory_nokmem __ro_after_init; /* Whether the swap controller is active */ #ifdef CONFIG_MEMCG_SWAP bool cgroup_memory_noswap __ro_after_init; #else #define cgroup_memory_noswap 1 #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) && !cgroup_memory_noswap; } #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 /* 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 notifier */ #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 task_is_dying(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 mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr) { return container_of(vmpr, struct mem_cgroup, vmpressure); } #ifdef CONFIG_MEMCG_KMEM static DEFINE_SPINLOCK(objcg_lock); bool mem_cgroup_kmem_disabled(void) { return cgroup_memory_nokmem; } static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, unsigned int nr_pages); static void obj_cgroup_release(struct percpu_ref *ref) { struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt); unsigned int nr_bytes; unsigned int nr_pages; unsigned long flags; /* * At this point all allocated objects are freed, and * objcg->nr_charged_bytes can't have an arbitrary byte value. * However, it can be PAGE_SIZE or (x * PAGE_SIZE). * * The following sequence can lead to it: * 1) CPU0: objcg == stock->cached_objcg * 2) CPU1: we do a small allocation (e.g. 92 bytes), * PAGE_SIZE bytes are charged * 3) CPU1: a process from another memcg is allocating something, * the stock if flushed, * objcg->nr_charged_bytes = PAGE_SIZE - 92 * 5) CPU0: we do release this object, * 92 bytes are added to stock->nr_bytes * 6) CPU0: stock is flushed, * 92 bytes are added to objcg->nr_charged_bytes * * In the result, nr_charged_bytes == PAGE_SIZE. * This page will be uncharged in obj_cgroup_release(). */ nr_bytes = atomic_read(&objcg->nr_charged_bytes); WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1)); nr_pages = nr_bytes >> PAGE_SHIFT; if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages); spin_lock_irqsave(&objcg_lock, flags); list_del(&objcg->list); spin_unlock_irqrestore(&objcg_lock, flags); percpu_ref_exit(ref); kfree_rcu(objcg, rcu); } static struct obj_cgroup *obj_cgroup_alloc(void) { struct obj_cgroup *objcg; int ret; objcg = kzalloc(sizeof(struct obj_cgroup), GFP_KERNEL); if (!objcg) return NULL; ret = percpu_ref_init(&objcg->refcnt, obj_cgroup_release, 0, GFP_KERNEL); if (ret) { kfree(objcg); return NULL; } INIT_LIST_HEAD(&objcg->list); return objcg; } static void memcg_reparent_objcgs(struct mem_cgroup *memcg, struct mem_cgroup *parent) { struct obj_cgroup *objcg, *iter; objcg = rcu_replace_pointer(memcg->objcg, NULL, true); spin_lock_irq(&objcg_lock); /* 1) Ready to reparent active objcg. */ list_add(&objcg->list, &memcg->objcg_list); /* 2) Reparent active objcg and already reparented objcgs to parent. */ list_for_each_entry(iter, &memcg->objcg_list, list) WRITE_ONCE(iter->memcg, parent); /* 3) Move already reparented objcgs to the parent's list */ list_splice(&memcg->objcg_list, &parent->objcg_list); spin_unlock_irq(&objcg_lock); percpu_ref_kill(&objcg->refcnt); } /* * This will be used as a shrinker list's index. * 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_slab_pre_alloc_hook() 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); #endif /** * 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_memcg(page); 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(); memcg = page_memcg_check(page); 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 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; } else { 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, int nid) { unsigned long excess; struct mem_cgroup_per_node *mz; struct mem_cgroup_tree_per_node *mctz; mctz = soft_limit_tree.rb_tree_per_node[nid]; 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 = memcg->nodeinfo[nid]; 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 = memcg->nodeinfo[nid]; mctz = soft_limit_tree.rb_tree_per_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; } /* * memcg and lruvec stats flushing * * Many codepaths leading to stats update or read are performance sensitive and * adding stats flushing in such codepaths is not desirable. So, to optimize the * flushing the kernel does: * * 1) Periodically and asynchronously flush the stats every 2 seconds to not let * rstat update tree grow unbounded. * * 2) Flush the stats synchronously on reader side only when there are more than * (MEMCG_CHARGE_BATCH * nr_cpus) update events. Though this optimization * will let stats be out of sync by atmost (MEMCG_CHARGE_BATCH * nr_cpus) but * only for 2 seconds due to (1). */ static void flush_memcg_stats_dwork(struct work_struct *w); static DECLARE_DEFERRABLE_WORK(stats_flush_dwork, flush_memcg_stats_dwork); static DEFINE_SPINLOCK(stats_flush_lock); static DEFINE_PER_CPU(unsigned int, stats_updates); static atomic_t stats_flush_threshold = ATOMIC_INIT(0); static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) { unsigned int x; cgroup_rstat_updated(memcg->css.cgroup, smp_processor_id()); x = __this_cpu_add_return(stats_updates, abs(val)); if (x > MEMCG_CHARGE_BATCH) { atomic_add(x / MEMCG_CHARGE_BATCH, &stats_flush_threshold); __this_cpu_write(stats_updates, 0); } } static void __mem_cgroup_flush_stats(void) { unsigned long flag; if (!spin_trylock_irqsave(&stats_flush_lock, flag)) return; cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup); atomic_set(&stats_flush_threshold, 0); spin_unlock_irqrestore(&stats_flush_lock, flag); } void mem_cgroup_flush_stats(void) { if (atomic_read(&stats_flush_threshold) > num_online_cpus()) __mem_cgroup_flush_stats(); } static void flush_memcg_stats_dwork(struct work_struct *w) { __mem_cgroup_flush_stats(); queue_delayed_work(system_unbound_wq, &stats_flush_dwork, 2UL*HZ); } /** * __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) { if (mem_cgroup_disabled()) return; __this_cpu_add(memcg->vmstats_percpu->state[idx], val); memcg_rstat_updated(memcg, val); } /* idx can be of type enum memcg_stat_item or node_stat_item. */ static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) { long x = 0; int cpu; for_each_possible_cpu(cpu) x += per_cpu(memcg->vmstats_percpu->state[idx], cpu); #ifdef CONFIG_SMP if (x < 0) x = 0; #endif return x; } void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, int val) { struct mem_cgroup_per_node *pn; struct mem_cgroup *memcg; pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); memcg = pn->memcg; /* Update memcg */ __this_cpu_add(memcg->vmstats_percpu->state[idx], val); /* Update lruvec */ __this_cpu_add(pn->lruvec_stats_percpu->state[idx], val); memcg_rstat_updated(memcg, val); } /** * __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) { /* Update node */ __mod_node_page_state(lruvec_pgdat(lruvec), idx, val); /* Update memcg and lruvec */ if (!mem_cgroup_disabled()) __mod_memcg_lruvec_state(lruvec, idx, val); } void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx, int val) { struct page *head = compound_head(page); /* rmap on tail pages */ struct mem_cgroup *memcg; pg_data_t *pgdat = page_pgdat(page); struct lruvec *lruvec; rcu_read_lock(); memcg = page_memcg(head); /* Untracked pages have no memcg, no lruvec. Update only the node */ if (!memcg) { rcu_read_unlock(); __mod_node_page_state(pgdat, idx, val); return; } lruvec = mem_cgroup_lruvec(memcg, pgdat); __mod_lruvec_state(lruvec, idx, val); rcu_read_unlock(); } EXPORT_SYMBOL(__mod_lruvec_page_state); void __mod_lruvec_kmem_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 we reparent the slab objects to the root memcg, * when we free the slab object, we need to update the per-memcg * vmstats to keep it correct for the root memcg. */ if (!memcg) { __mod_node_page_state(pgdat, idx, val); } else { lruvec = mem_cgroup_lruvec(memcg, pgdat); __mod_lruvec_state(lruvec, 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 occurred */ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, unsigned long count) { if (mem_cgroup_disabled()) return; __this_cpu_add(memcg->vmstats_percpu->events[idx], count); memcg_rstat_updated(memcg, count); } static unsigned long memcg_events(struct mem_cgroup *memcg, int event) { return READ_ONCE(memcg->vmstats.events[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_percpu->events[event], cpu); return x; } static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, int 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, int nid) { /* 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, nid); } } 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); static __always_inline struct mem_cgroup *active_memcg(void) { if (!in_task()) return this_cpu_read(int_active_memcg); else return current->active_memcg; } /** * 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. If mm * is NULL, then the memcg is chosen as follows: * 1) The active memcg, if set. * 2) current->mm->memcg, if available * 3) root memcg * 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; /* * Page cache insertions can happen without an * actual mm context, e.g. during disk probing * on boot, loopback IO, acct() writes etc. * * No need to css_get on root memcg as the reference * counting is disabled on the root level in the * cgroup core. See CSS_NO_REF. */ if (unlikely(!mm)) { memcg = active_memcg(); if (unlikely(memcg)) { /* remote memcg must hold a ref */ css_get(&memcg->css); return memcg; } mm = current->mm; if (unlikely(!mm)) return root_mem_cgroup; } rcu_read_lock(); do { 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); static __always_inline bool memcg_kmem_bypass(void) { /* Allow remote memcg charging from any context. */ if (unlikely(active_memcg())) return false; /* Memcg to charge can't be determined. */ if (!in_task() || !current->mm || (current->flags & PF_KTHREAD)) return true; return false; } /** * 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 in @reclaim to divide up the memcgs * in the hierarchy among all concurrent reclaimers operating on the * same node. */ 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 *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; rcu_read_lock(); if (reclaim) { struct mem_cgroup_per_node *mz; mz = root->nodeinfo[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(); 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 = from->nodeinfo[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; } #ifdef CONFIG_DEBUG_VM void lruvec_memcg_debug(struct lruvec *lruvec, struct folio *folio) { struct mem_cgroup *memcg; if (mem_cgroup_disabled()) return; memcg = folio_memcg(folio); if (!memcg) VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != root_mem_cgroup, folio); else VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != memcg, folio); } #endif /** * folio_lruvec_lock - Lock the lruvec for a folio. * @folio: Pointer to the folio. * * These functions are safe to use under any of the following conditions: * - folio locked * - folio_test_lru false * - folio_memcg_lock() * - folio frozen (refcount of 0) * * Return: The lruvec this folio is on with its lock held. */ struct lruvec *folio_lruvec_lock(struct folio *folio) { struct lruvec *lruvec = folio_lruvec(folio); spin_lock(&lruvec->lru_lock); lruvec_memcg_debug(lruvec, folio); return lruvec; } /** * folio_lruvec_lock_irq - Lock the lruvec for a folio. * @folio: Pointer to the folio. * * These functions are safe to use under any of the following conditions: * - folio locked * - folio_test_lru false * - folio_memcg_lock() * - folio frozen (refcount of 0) * * Return: The lruvec this folio is on with its lock held and interrupts * disabled. */ struct lruvec *folio_lruvec_lock_irq(struct folio *folio) { struct lruvec *lruvec = folio_lruvec(folio); spin_lock_irq(&lruvec->lru_lock); lruvec_memcg_debug(lruvec, folio); return lruvec; } /** * folio_lruvec_lock_irqsave - Lock the lruvec for a folio. * @folio: Pointer to the folio. * @flags: Pointer to irqsave flags. * * These functions are safe to use under any of the following conditions: * - folio locked * - folio_test_lru false * - folio_memcg_lock() * - folio frozen (refcount of 0) * * Return: The lruvec this folio is on with its lock held and interrupts * disabled. */ struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio, unsigned long *flags) { struct lruvec *lruvec = folio_lruvec(folio); spin_lock_irqsave(&lruvec->lru_lock, *flags); lruvec_memcg_debug(lruvec, folio); 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. */ 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; } struct memory_stat { const char *name; unsigned int idx; }; static const struct memory_stat memory_stats[] = { { "anon", NR_ANON_MAPPED }, { "file", NR_FILE_PAGES }, { "kernel_stack", NR_KERNEL_STACK_KB }, { "pagetables", NR_PAGETABLE }, { "percpu", MEMCG_PERCPU_B }, { "sock", MEMCG_SOCK }, { "vmalloc", MEMCG_VMALLOC }, { "shmem", NR_SHMEM }, { "file_mapped", NR_FILE_MAPPED }, { "file_dirty", NR_FILE_DIRTY }, { "file_writeback", NR_WRITEBACK }, #ifdef CONFIG_SWAP { "swapcached", NR_SWAPCACHE }, #endif #ifdef CONFIG_TRANSPARENT_HUGEPAGE { "anon_thp", NR_ANON_THPS }, { "file_thp", NR_FILE_THPS }, { "shmem_thp", NR_SHMEM_THPS }, #endif { "inactive_anon", NR_INACTIVE_ANON }, { "active_anon", NR_ACTIVE_ANON }, { "inactive_file", NR_INACTIVE_FILE }, { "active_file", NR_ACTIVE_FILE }, { "unevictable", NR_UNEVICTABLE }, { "slab_reclaimable", NR_SLAB_RECLAIMABLE_B }, { "slab_unreclaimable", NR_SLAB_UNRECLAIMABLE_B }, /* The memory events */ { "workingset_refault_anon", WORKINGSET_REFAULT_ANON }, { "workingset_refault_file", WORKINGSET_REFAULT_FILE }, { "workingset_activate_anon", WORKINGSET_ACTIVATE_ANON }, { "workingset_activate_file", WORKINGSET_ACTIVATE_FILE }, { "workingset_restore_anon", WORKINGSET_RESTORE_ANON }, { "workingset_restore_file", WORKINGSET_RESTORE_FILE }, { "workingset_nodereclaim", WORKINGSET_NODERECLAIM }, }; /* Translate stat items to the correct unit for memory.stat output */ static int memcg_page_state_unit(int item) { switch (item) { case MEMCG_PERCPU_B: case NR_SLAB_RECLAIMABLE_B: case NR_SLAB_UNRECLAIMABLE_B: case WORKINGSET_REFAULT_ANON: case WORKINGSET_REFAULT_FILE: case WORKINGSET_ACTIVATE_ANON: case WORKINGSET_ACTIVATE_FILE: case WORKINGSET_RESTORE_ANON: case WORKINGSET_RESTORE_FILE: case WORKINGSET_NODERECLAIM: return 1; case NR_KERNEL_STACK_KB: return SZ_1K; default: return PAGE_SIZE; } } static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item) { return memcg_page_state(memcg, item) * memcg_page_state_unit(item); } 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: */ mem_cgroup_flush_stats(); for (i = 0; i < ARRAY_SIZE(memory_stats); i++) { u64 size; size = memcg_page_state_output(memcg, memory_stats[i].idx); seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size); if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) { size += memcg_page_state_output(memcg, NR_SLAB_RECLAIMABLE_B); seq_buf_printf(&s, "slab %llu\n", 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, "%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 = READ_ONCE(memcg->memory.max); if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) { if (mem_cgroup_swappiness(memcg)) max += min(READ_ONCE(memcg->swap.max), (unsigned long)total_swap_pages); } else { /* v1 */ if (mem_cgroup_swappiness(memcg)) { /* Calculate swap excess capacity from memsw limit */ unsigned long swap = READ_ONCE(memcg->memsw.max) - max; max += min(swap, (unsigned long)total_swap_pages); } } 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 = true; if (mutex_lock_killable(&oom_lock)) return true; if (mem_cgroup_margin(memcg) >= (1 << order)) goto unlock; /* * A few threads which were not waiting at mutex_lock_killable() can * fail to bail out. Therefore, check again after holding oom_lock. */ ret = task_is_dying() || out_of_memory(&oc); unlock: 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; /* * Be careful about under_oom underflows because a child memcg * could have been added after mem_cgroup_mark_under_oom. */ 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 explicitly. */ 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"); } /** * folio_memcg_lock - Bind a folio to its memcg. * @folio: The folio. * * This function prevents unlocked LRU folios from being moved to * another cgroup. * * It ensures lifetime of the bound memcg. The caller is responsible * for the lifetime of the folio. */ void folio_memcg_lock(struct folio *folio) { 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. */ rcu_read_lock(); if (mem_cgroup_disabled()) return; again: memcg = folio_memcg(folio); if (unlikely(!memcg)) return; #ifdef CONFIG_PROVE_LOCKING local_irq_save(flags); might_lock(&memcg->move_lock); local_irq_restore(flags); #endif if (atomic_read(&memcg->moving_account) <= 0) return; spin_lock_irqsave(&memcg->move_lock, flags); if (memcg != folio_memcg(folio)) { spin_unlock_irqrestore(&memcg->move_lock, flags); goto again; } /* * When charge migration first begins, we can have multiple * critical sections holding the fast-path RCU lock and one * holding the slowpath move_lock. Track the task who has the * move_lock for unlock_page_memcg(). */ memcg->move_lock_task = current; memcg->move_lock_flags = flags; } void lock_page_memcg(struct page *page) { folio_memcg_lock(page_folio(page)); } static void __folio_memcg_unlock(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(); } /** * folio_memcg_unlock - Release the binding between a folio and its memcg. * @folio: The folio. * * This releases the binding created by folio_memcg_lock(). This does * not change the accounting of this folio to its memcg, but it does * permit others to change it. */ void folio_memcg_unlock(struct folio *folio) { __folio_memcg_unlock(folio_memcg(folio)); } void unlock_page_memcg(struct page *page) { folio_memcg_unlock(page_folio(page)); } struct obj_stock { #ifdef CONFIG_MEMCG_KMEM struct obj_cgroup *cached_objcg; struct pglist_data *cached_pgdat; unsigned int nr_bytes; int nr_slab_reclaimable_b; int nr_slab_unreclaimable_b; #else int dummy[0]; #endif }; struct memcg_stock_pcp { struct mem_cgroup *cached; /* this never be root cgroup */ unsigned int nr_pages; struct obj_stock task_obj; struct obj_stock irq_obj; 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); #ifdef CONFIG_MEMCG_KMEM static void drain_obj_stock(struct obj_stock *stock); static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg); #else static inline void drain_obj_stock(struct obj_stock *stock) { } static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg) { return false; } #endif /** * 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 (!old) return; if (stock->nr_pages) { page_counter_uncharge(&old->memory, stock->nr_pages); if (do_memsw_account()) page_counter_uncharge(&old->memsw, stock->nr_pages); stock->nr_pages = 0; } css_put(&old->css); stock->cached = NULL; } static void drain_local_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock; unsigned long flags; /* * The only protection from cpu hotplug (memcg_hotplug_cpu_dead) 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_obj_stock(&stock->irq_obj); if (in_task()) drain_obj_stock(&stock->task_obj); 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); css_get(&memcg->css); 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; else if (obj_stock_flush_required(stock, 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; stock = &per_cpu(memcg_stock, cpu); drain_stock(stock); return 0; } static unsigned long reclaim_high(struct mem_cgroup *memcg, unsigned int nr_pages, gfp_t gfp_mask) { unsigned long nr_reclaimed = 0; do { unsigned long pflags; if (page_counter_read(&memcg->memory) <= READ_ONCE(memcg->memory.high)) continue; memcg_memory_event(memcg, MEMCG_HIGH); psi_memstall_enter(&pflags); nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); psi_memstall_leave(&pflags); } while ((memcg = parent_mem_cgroup(memcg)) && !mem_cgroup_is_root(memcg)); return nr_reclaimed; } 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 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 long nr_reclaimed; unsigned int nr_pages = current->memcg_nr_pages_over_high; int nr_retries = MAX_RECLAIM_RETRIES; struct mem_cgroup *memcg; bool in_retry = false; if (likely(!nr_pages)) return; memcg = get_mem_cgroup_from_mm(current->mm); current->memcg_nr_pages_over_high = 0; retry_reclaim: /* * The allocating task should reclaim at least the batch size, but for * subsequent retries we only want to do what's necessary to prevent oom * or breaching resource isolation. * * This is distinct from memory.max or page allocator behaviour because * memory.high is currently batched, whereas memory.max and the page * allocator run every time an allocation is made. */ nr_reclaimed = reclaim_high(memcg, in_retry ? SWAP_CLUSTER_MAX : nr_pages, GFP_KERNEL); /* * 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 reclaim is making forward progress but we're still over * memory.high, we want to encourage that rather than doing allocator * throttling. */ if (nr_reclaimed || nr_retries--) { in_retry = true; goto retry_reclaim; } /* * 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_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages) { unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); int nr_retries = MAX_RECLAIM_RETRIES; struct mem_cgroup *mem_over_limit; struct page_counter *counter; enum oom_status oom_status; unsigned long nr_reclaimed; bool passed_oom = false; bool may_swap = true; bool drained = false; unsigned long pflags; 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; /* * 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); psi_memstall_enter(&pflags); nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, gfp_mask, may_swap); psi_memstall_leave(&pflags); 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; /* Avoid endless loop for tasks bypassed by the oom killer */ if (passed_oom && task_is_dying()) goto nomem; /* * 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)); if (oom_status == OOM_SUCCESS) { passed_oom = true; nr_retries = MAX_RECLAIM_RETRIES; goto retry; } 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); return 0; done_restock: 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 inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages) { if (mem_cgroup_is_root(memcg)) return 0; return try_charge_memcg(memcg, gfp_mask, nr_pages); } static inline 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); } static void commit_charge(struct folio *folio, struct mem_cgroup *memcg) { VM_BUG_ON_FOLIO(folio_memcg(folio), folio); /* * Any of the following ensures page's memcg stability: * * - the page lock * - LRU isolation * - lock_page_memcg() * - exclusive reference */ folio->memcg_data = (unsigned long)memcg; } static struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg) { struct mem_cgroup *memcg; rcu_read_lock(); retry: memcg = obj_cgroup_memcg(objcg); if (unlikely(!css_tryget(&memcg->css))) goto retry; rcu_read_unlock(); return memcg; } #ifdef CONFIG_MEMCG_KMEM /* * The allocated objcg pointers array is not accounted directly. * Moreover, it should not come from DMA buffer and is not readily * reclaimable. So those GFP bits should be masked off. */ #define OBJCGS_CLEAR_MASK (__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT) /* * Most kmem_cache_alloc() calls are from user context. The irq disable/enable * sequence used in this case to access content from object stock is slow. * To optimize for user context access, there are now two object stocks for * task context and interrupt context access respectively. * * The task context object stock can be accessed by disabling preemption only * which is cheap in non-preempt kernel. The interrupt context object stock * can only be accessed after disabling interrupt. User context code can * access interrupt object stock, but not vice versa. */ static inline struct obj_stock *get_obj_stock(unsigned long *pflags) { struct memcg_stock_pcp *stock; if (likely(in_task())) { *pflags = 0UL; preempt_disable(); stock = this_cpu_ptr(&memcg_stock); return &stock->task_obj; } local_irq_save(*pflags); stock = this_cpu_ptr(&memcg_stock); return &stock->irq_obj; } static inline void put_obj_stock(unsigned long flags) { if (likely(in_task())) preempt_enable(); else local_irq_restore(flags); } /* * mod_objcg_mlstate() may be called with irq enabled, so * mod_memcg_lruvec_state() should be used. */ static inline void mod_objcg_mlstate(struct obj_cgroup *objcg, struct pglist_data *pgdat, enum node_stat_item idx, int nr) { struct mem_cgroup *memcg; struct lruvec *lruvec; rcu_read_lock(); memcg = obj_cgroup_memcg(objcg); lruvec = mem_cgroup_lruvec(memcg, pgdat); mod_memcg_lruvec_state(lruvec, idx, nr); rcu_read_unlock(); } int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s, gfp_t gfp, bool new_slab) { unsigned int objects = objs_per_slab(s, slab); unsigned long memcg_data; void *vec; gfp &= ~OBJCGS_CLEAR_MASK; vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp, slab_nid(slab)); if (!vec) return -ENOMEM; memcg_data = (unsigned long) vec | MEMCG_DATA_OBJCGS; if (new_slab) { /* * If the slab is brand new and nobody can yet access its * memcg_data, no synchronization is required and memcg_data can * be simply assigned. */ slab->memcg_data = memcg_data; } else if (cmpxchg(&slab->memcg_data, 0, memcg_data)) { /* * If the slab is already in use, somebody can allocate and * assign obj_cgroups in parallel. In this case the existing * objcg vector should be reused. */ kfree(vec); return 0; } kmemleak_not_leak(vec); return 0; } /* * Returns a pointer to the memory cgroup to which the kernel object is charged. * * A passed kernel object can be a slab object or a generic kernel page, so * different mechanisms for getting the memory cgroup pointer should be used. * In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller * can not know for sure how the kernel object is implemented. * mem_cgroup_from_obj() can be safely used in such cases. * * 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 folio *folio; if (mem_cgroup_disabled()) return NULL; folio = virt_to_folio(p); /* * Slab objects are accounted individually, not per-page. * Memcg membership data for each individual object is saved in * slab->memcg_data. */ if (folio_test_slab(folio)) { struct obj_cgroup **objcgs; struct slab *slab; unsigned int off; slab = folio_slab(folio); objcgs = slab_objcgs(slab); if (!objcgs) return NULL; off = obj_to_index(slab->slab_cache, slab, p); if (objcgs[off]) return obj_cgroup_memcg(objcgs[off]); return NULL; } /* * page_memcg_check() is used here, because in theory we can encounter * a folio where the slab flag has been cleared already, but * slab->memcg_data has not been freed yet * page_memcg_check(page) will guarantee that a proper memory * cgroup pointer or NULL will be returned. */ return page_memcg_check(folio_page(folio, 0)); } __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) { struct obj_cgroup *objcg = NULL; struct mem_cgroup *memcg; if (memcg_kmem_bypass()) return NULL; rcu_read_lock(); if (unlikely(active_memcg())) memcg = active_memcg(); else memcg = mem_cgroup_from_task(current); for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) { objcg = rcu_dereference(memcg->objcg); if (objcg && obj_cgroup_tryget(objcg)) break; objcg = NULL; } rcu_read_unlock(); return objcg; } 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_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); } /* * obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg * @objcg: object cgroup to uncharge * @nr_pages: number of pages to uncharge */ static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, unsigned int nr_pages) { struct mem_cgroup *memcg; memcg = get_mem_cgroup_from_objcg(objcg); if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) page_counter_uncharge(&memcg->kmem, nr_pages); refill_stock(memcg, nr_pages); css_put(&memcg->css); } /* * obj_cgroup_charge_pages: charge a number of kernel pages to a objcg * @objcg: object cgroup to charge * @gfp: reclaim mode * @nr_pages: number of pages to charge * * Returns 0 on success, an error code on failure. */ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp, unsigned int nr_pages) { struct mem_cgroup *memcg; int ret; memcg = get_mem_cgroup_from_objcg(objcg); ret = try_charge_memcg(memcg, gfp, nr_pages); if (ret) goto out; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) page_counter_charge(&memcg->kmem, nr_pages); out: css_put(&memcg->css); return ret; } /** * __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 obj_cgroup *objcg; int ret = 0; objcg = get_obj_cgroup_from_current(); if (objcg) { ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order); if (!ret) { page->memcg_data = (unsigned long)objcg | MEMCG_DATA_KMEM; return 0; } obj_cgroup_put(objcg); } 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 folio *folio = page_folio(page); struct obj_cgroup *objcg; unsigned int nr_pages = 1 << order; if (!folio_memcg_kmem(folio)) return; objcg = __folio_objcg(folio); obj_cgroup_uncharge_pages(objcg, nr_pages); folio->memcg_data = 0; obj_cgroup_put(objcg); } void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, enum node_stat_item idx, int nr) { unsigned long flags; struct obj_stock *stock = get_obj_stock(&flags); int *bytes; /* * Save vmstat data in stock and skip vmstat array update unless * accumulating over a page of vmstat data or when pgdat or idx * changes. */ if (stock->cached_objcg != objcg) { drain_obj_stock(stock); obj_cgroup_get(objcg); stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; stock->cached_objcg = objcg; stock->cached_pgdat = pgdat; } else if (stock->cached_pgdat != pgdat) { /* Flush the existing cached vmstat data */ struct pglist_data *oldpg = stock->cached_pgdat; if (stock->nr_slab_reclaimable_b) { mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B, stock->nr_slab_reclaimable_b); stock->nr_slab_reclaimable_b = 0; } if (stock->nr_slab_unreclaimable_b) { mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B, stock->nr_slab_unreclaimable_b); stock->nr_slab_unreclaimable_b = 0; } stock->cached_pgdat = pgdat; } bytes = (idx == NR_SLAB_RECLAIMABLE_B) ? &stock->nr_slab_reclaimable_b : &stock->nr_slab_unreclaimable_b; /* * Even for large object >= PAGE_SIZE, the vmstat data will still be * cached locally at least once before pushing it out. */ if (!*bytes) { *bytes = nr; nr = 0; } else { *bytes += nr; if (abs(*bytes) > PAGE_SIZE) { nr = *bytes; *bytes = 0; } else { nr = 0; } } if (nr) mod_objcg_mlstate(objcg, pgdat, idx, nr); put_obj_stock(flags); } static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) { unsigned long flags; struct obj_stock *stock = get_obj_stock(&flags); bool ret = false; if (objcg == stock->cached_objcg && stock->nr_bytes >= nr_bytes) { stock->nr_bytes -= nr_bytes; ret = true; } put_obj_stock(flags); return ret; } static void drain_obj_stock(struct obj_stock *stock) { struct obj_cgroup *old = stock->cached_objcg; if (!old) return; if (stock->nr_bytes) { unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT; unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1); if (nr_pages) obj_cgroup_uncharge_pages(old, nr_pages); /* * The leftover is flushed to the centralized per-memcg value. * On the next attempt to refill obj stock it will be moved * to a per-cpu stock (probably, on an other CPU), see * refill_obj_stock(). * * How often it's flushed is a trade-off between the memory * limit enforcement accuracy and potential CPU contention, * so it might be changed in the future. */ atomic_add(nr_bytes, &old->nr_charged_bytes); stock->nr_bytes = 0; } /* * Flush the vmstat data in current stock */ if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) { if (stock->nr_slab_reclaimable_b) { mod_objcg_mlstate(old, stock->cached_pgdat, NR_SLAB_RECLAIMABLE_B, stock->nr_slab_reclaimable_b); stock->nr_slab_reclaimable_b = 0; } if (stock->nr_slab_unreclaimable_b) { mod_objcg_mlstate(old, stock->cached_pgdat, NR_SLAB_UNRECLAIMABLE_B, stock->nr_slab_unreclaimable_b); stock->nr_slab_unreclaimable_b = 0; } stock->cached_pgdat = NULL; } obj_cgroup_put(old); stock->cached_objcg = NULL; } static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg) { struct mem_cgroup *memcg; if (in_task() && stock->task_obj.cached_objcg) { memcg = obj_cgroup_memcg(stock->task_obj.cached_objcg); if (memcg && mem_cgroup_is_descendant(memcg, root_memcg)) return true; } if (stock->irq_obj.cached_objcg) { memcg = obj_cgroup_memcg(stock->irq_obj.cached_objcg); if (memcg && mem_cgroup_is_descendant(memcg, root_memcg)) return true; } return false; } static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, bool allow_uncharge) { unsigned long flags; struct obj_stock *stock = get_obj_stock(&flags); unsigned int nr_pages = 0; if (stock->cached_objcg != objcg) { /* reset if necessary */ drain_obj_stock(stock); obj_cgroup_get(objcg); stock->cached_objcg = objcg; stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; allow_uncharge = true; /* Allow uncharge when objcg changes */ } stock->nr_bytes += nr_bytes; if (allow_uncharge && (stock->nr_bytes > PAGE_SIZE)) { nr_pages = stock->nr_bytes >> PAGE_SHIFT; stock->nr_bytes &= (PAGE_SIZE - 1); } put_obj_stock(flags); if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages); } int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size) { unsigned int nr_pages, nr_bytes; int ret; if (consume_obj_stock(objcg, size)) return 0; /* * In theory, objcg->nr_charged_bytes can have enough * pre-charged bytes to satisfy the allocation. However, * flushing objcg->nr_charged_bytes requires two atomic * operations, and objcg->nr_charged_bytes can't be big. * The shared objcg->nr_charged_bytes can also become a * performance bottleneck if all tasks of the same memcg are * trying to update it. So it's better to ignore it and try * grab some new pages. The stock's nr_bytes will be flushed to * objcg->nr_charged_bytes later on when objcg changes. * * The stock's nr_bytes may contain enough pre-charged bytes * to allow one less page from being charged, but we can't rely * on the pre-charged bytes not being changed outside of * consume_obj_stock() or refill_obj_stock(). So ignore those * pre-charged bytes as well when charging pages. To avoid a * page uncharge right after a page charge, we set the * allow_uncharge flag to false when calling refill_obj_stock() * to temporarily allow the pre-charged bytes to exceed the page * size limit. The maximum reachable value of the pre-charged * bytes is (sizeof(object) + PAGE_SIZE - 2) if there is no data * race. */ nr_pages = size >> PAGE_SHIFT; nr_bytes = size & (PAGE_SIZE - 1); if (nr_bytes) nr_pages += 1; ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages); if (!ret && nr_bytes) refill_obj_stock(objcg, PAGE_SIZE - nr_bytes, false); return ret; } void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size) { refill_obj_stock(objcg, size, true); } #endif /* CONFIG_MEMCG_KMEM */ /* * Because page_memcg(head) is not set on tails, set it now. */ void split_page_memcg(struct page *head, unsigned int nr) { struct folio *folio = page_folio(head); struct mem_cgroup *memcg = folio_memcg(folio); int i; if (mem_cgroup_disabled() || !memcg) return; for (i = 1; i < nr; i++) folio_page(folio, i)->memcg_data = folio->memcg_data; if (folio_memcg_kmem(folio)) obj_cgroup_get_many(__folio_objcg(folio), nr - 1); else css_get_many(&memcg->css, nr - 1); } #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.rb_tree_per_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; } /* * 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 = MAX_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)) { if (signal_pending(current)) return -EINTR; if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true)) nr_retries--; } 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 1; } static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val) { if (val == 1) return 0; pr_warn_once("Non-hierarchical mode is deprecated. " "Please report your usecase to linux-mm@kvack.org if you " "depend on this functionality.\n"); return -EINVAL; } static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) { unsigned long val; if (mem_cgroup_is_root(memcg)) { mem_cgroup_flush_stats(); val = memcg_page_state(memcg, NR_FILE_PAGES) + memcg_page_state(memcg, NR_ANON_MAPPED); 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(); } } #ifdef CONFIG_MEMCG_KMEM static int memcg_online_kmem(struct mem_cgroup *memcg) { struct obj_cgroup *objcg; int memcg_id; if (cgroup_memory_nokmem) return 0; BUG_ON(memcg->kmemcg_id >= 0); memcg_id = memcg_alloc_cache_id(); if (memcg_id < 0) return memcg_id; objcg = obj_cgroup_alloc(); if (!objcg) { memcg_free_cache_id(memcg_id); return -ENOMEM; } objcg->memcg = memcg; rcu_assign_pointer(memcg->objcg, objcg); static_branch_enable(&memcg_kmem_enabled_key); memcg->kmemcg_id = memcg_id; return 0; } static void memcg_offline_kmem(struct mem_cgroup *memcg) { struct mem_cgroup *parent; int kmemcg_id; if (memcg->kmemcg_id == -1) return; parent = parent_mem_cgroup(memcg); if (!parent) parent = root_mem_cgroup; memcg_reparent_objcgs(memcg, parent); kmemcg_id = memcg->kmemcg_id; BUG_ON(kmemcg_id < 0); /* * After we have finished memcg_reparent_objcgs(), 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(). */ memcg_drain_all_list_lrus(kmemcg_id, parent); memcg_free_cache_id(kmemcg_id); memcg->kmemcg_id = -1; } #else static int memcg_online_kmem(struct mem_cgroup *memcg) { return 0; } static void memcg_offline_kmem(struct mem_cgroup *memcg) { } #endif /* CONFIG_MEMCG_KMEM */ 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: /* kmem.limit_in_bytes is deprecated. */ ret = -EOPNOTSUPP; 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, bool tree) { 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; if (tree) nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru); else 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, bool tree) { unsigned long nr = 0; enum lru_list lru; for_each_lru(lru) { if (!(BIT(lru) & lru_mask)) continue; if (tree) nr += memcg_page_state(memcg, NR_LRU_BASE + lru); else 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; struct mem_cgroup *memcg = mem_cgroup_from_seq(m); mem_cgroup_flush_stats(); for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { seq_printf(m, "%s=%lu", stat->name, mem_cgroup_nr_lru_pages(memcg, stat->lru_mask, false)); for_each_node_state(nid, N_MEMORY) seq_printf(m, " N%d=%lu", nid, mem_cgroup_node_nr_lru_pages(memcg, nid, stat->lru_mask, false)); seq_putc(m, '\n'); } for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { seq_printf(m, "hierarchical_%s=%lu", stat->name, mem_cgroup_nr_lru_pages(memcg, stat->lru_mask, true)); for_each_node_state(nid, N_MEMORY) seq_printf(m, " N%d=%lu", nid, mem_cgroup_node_nr_lru_pages(memcg, nid, stat->lru_mask, true)); seq_putc(m, '\n'); } return 0; } #endif /* CONFIG_NUMA */ static const unsigned int memcg1_stats[] = { NR_FILE_PAGES, NR_ANON_MAPPED, #ifdef CONFIG_TRANSPARENT_HUGEPAGE NR_ANON_THPS, #endif NR_SHMEM, NR_FILE_MAPPED, NR_FILE_DIRTY, NR_WRITEBACK, MEMCG_SWAP, }; static const char *const memcg1_stat_names[] = { "cache", "rss", #ifdef CONFIG_TRANSPARENT_HUGEPAGE "rss_huge", #endif "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)); mem_cgroup_flush_stats(); for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { unsigned long nr; if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) continue; nr = memcg_page_state_local(memcg, memcg1_stats[i]); seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * 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++) { unsigned long nr; if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) continue; nr = memcg_page_state(memcg, memcg1_stats[i]); seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], (u64)nr * 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; unsigned long anon_cost = 0; unsigned long file_cost = 0; for_each_online_pgdat(pgdat) { mz = memcg->nodeinfo[pgdat->node_id]; anon_cost += mz->lruvec.anon_cost; file_cost += mz->lruvec.file_cost; } seq_printf(m, "anon_cost %lu\n", anon_cost); seq_printf(m, "file_cost %lu\n", file_cost); } #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 > 200) return -EINVAL; if (!mem_cgroup_is_root(memcg)) 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, flex_array_size(new, entries, size - 1)); /* 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(*new->entries), 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 (mem_cgroup_is_root(memcg) || !((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; } /** * 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; mem_cgroup_flush_stats(); *pdirty = memcg_page_state(memcg, NR_FILE_DIRTY); *pwriteback = memcg_page_state(memcg, NR_WRITEBACK); *pfilepages = memcg_page_state(memcg, NR_INACTIVE_FILE) + memcg_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 * tracks 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 repeatedly and * severely throttled after making some progress after each * dirty_expire_interval while the underlying 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 folio *folio, struct bdi_writeback *wb) { struct mem_cgroup *memcg = folio_memcg(folio); struct memcg_cgwb_frn *frn; u64 now = get_jiffies_64(); u64 oldest_at = now; int oldest = -1; int i; trace_track_foreign_dirty(folio, 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, 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 = file_permission(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_irq(&memcg->event_list_lock); list_add(&event->list, &memcg->event_list); spin_unlock_irq(&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; } #if defined(CONFIG_MEMCG_KMEM) && (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)) static int mem_cgroup_slab_show(struct seq_file *m, void *p) { /* * Deprecated. * Please, take a look at tools/cgroup/slabinfo.py . */ return 0; } #endif 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_show = mem_cgroup_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 offline 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_stats_percpu = alloc_percpu_gfp(struct lruvec_stats_percpu, GFP_KERNEL_ACCOUNT); if (!pn->lruvec_stats_percpu) { 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_stats_percpu); 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); kfree(memcg); } static void mem_cgroup_free(struct mem_cgroup *memcg) { memcg_wb_domain_exit(memcg); __mem_cgroup_free(memcg); } static struct mem_cgroup *mem_cgroup_alloc(void) { struct mem_cgroup *memcg; int node; int __maybe_unused i; long error = -ENOMEM; memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), 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_percpu = alloc_percpu_gfp(struct memcg_vmstats_percpu, GFP_KERNEL_ACCOUNT); 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; INIT_LIST_HEAD(&memcg->objcg_list); #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, *old_memcg; long error = -ENOMEM; old_memcg = set_active_memcg(parent); memcg = mem_cgroup_alloc(); set_active_memcg(old_memcg); 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; page_counter_init(&memcg->memory, &parent->memory); page_counter_init(&memcg->swap, &parent->swap); 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->kmem, NULL); page_counter_init(&memcg->tcpmem, NULL); root_mem_cgroup = memcg; return &memcg->css; } /* The following stuff does not apply to the root */ 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 expand_shrinker_info() * by the time the maps are allocated. So, we allocate maps * here, when for_each_mem_cgroup() can't skip it. */ if (alloc_shrinker_info(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); if (unlikely(mem_cgroup_is_root(memcg))) queue_delayed_work(system_unbound_wq, &stats_flush_dwork, 2UL*HZ); 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_irq(&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_irq(&memcg->event_list_lock); page_counter_set_min(&memcg->memory, 0); page_counter_set_low(&memcg->memory, 0); memcg_offline_kmem(memcg); reparent_shrinker_deferred(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); free_shrinker_info(memcg); /* Need to offline kmem if online_css() fails */ memcg_offline_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->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); } static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent = parent_mem_cgroup(memcg); struct memcg_vmstats_percpu *statc; long delta, v; int i, nid; statc = per_cpu_ptr(memcg->vmstats_percpu, cpu); for (i = 0; i < MEMCG_NR_STAT; i++) { /* * Collect the aggregated propagation counts of groups * below us. We're in a per-cpu loop here and this is * a global counter, so the first cycle will get them. */ delta = memcg->vmstats.state_pending[i]; if (delta) memcg->vmstats.state_pending[i] = 0; /* Add CPU changes on this level since the last flush */ v = READ_ONCE(statc->state[i]); if (v != statc->state_prev[i]) { delta += v - statc->state_prev[i]; statc->state_prev[i] = v; } if (!delta) continue; /* Aggregate counts on this level and propagate upwards */ memcg->vmstats.state[i] += delta; if (parent) parent->vmstats.state_pending[i] += delta; } for (i = 0; i < NR_VM_EVENT_ITEMS; i++) { delta = memcg->vmstats.events_pending[i]; if (delta) memcg->vmstats.events_pending[i] = 0; v = READ_ONCE(statc->events[i]); if (v != statc->events_prev[i]) { delta += v - statc->events_prev[i]; statc->events_prev[i] = v; } if (!delta) continue; memcg->vmstats.events[i] += delta; if (parent) parent->vmstats.events_pending[i] += delta; } for_each_node_state(nid, N_MEMORY) { struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid]; struct mem_cgroup_per_node *ppn = NULL; struct lruvec_stats_percpu *lstatc; if (parent) ppn = parent->nodeinfo[nid]; lstatc = per_cpu_ptr(pn->lruvec_stats_percpu, cpu); for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) { delta = pn->lruvec_stats.state_pending[i]; if (delta) pn->lruvec_stats.state_pending[i] = 0; v = READ_ONCE(lstatc->state[i]); if (v != lstatc->state_prev[i]) { delta += v - lstatc->state_prev[i]; lstatc->state_prev[i] = v; } if (!delta) continue; pn->lruvec_stats.state[i] += delta; if (ppn) ppn->lruvec_stats.state_pending[i] += delta; } } } #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)) return NULL; /* * Handle device private pages that are not accessible by the CPU, but * stored as special swap entries in the page table. */ if (is_device_private_entry(ent)) { page = pfn_swap_entry_to_page(ent); if (!get_page_unless_zero(page)) return NULL; return page; } if (non_swap_entry(ent)) return NULL; /* * Because lookup_swap_cache() updates some statistics counter, * we call find_get_page() with swapper_space directly. */ page = find_get_page(swap_address_space(ent), swp_offset(ent)); 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) { if (!vma->vm_file) /* anonymous vma */ return NULL; if (!(mc.flags & MOVE_FILE)) return NULL; /* page is moved even if it's not RSS of this task(page-faulted). */ /* shmem/tmpfs may report page out on swap: account for that too. */ return find_get_incore_page(vma->vm_file->f_mapping, linear_page_index(vma, addr)); } /** * 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 folio *folio = page_folio(page); struct lruvec *from_vec, *to_vec; struct pglist_data *pgdat; unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1; int nid, ret; VM_BUG_ON(from == to); VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); VM_BUG_ON(compound && !folio_test_large(folio)); /* * Prevent mem_cgroup_migrate() from looking at * page's memory cgroup of its source page while we change it. */ ret = -EBUSY; if (!folio_trylock(folio)) goto out; ret = -EINVAL; if (folio_memcg(folio) != from) goto out_unlock; pgdat = folio_pgdat(folio); from_vec = mem_cgroup_lruvec(from, pgdat); to_vec = mem_cgroup_lruvec(to, pgdat); folio_memcg_lock(folio); if (folio_test_anon(folio)) { if (folio_mapped(folio)) { __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages); __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages); if (folio_test_transhuge(folio)) { __mod_lruvec_state(from_vec, NR_ANON_THPS, -nr_pages); __mod_lruvec_state(to_vec, NR_ANON_THPS, nr_pages); } } } else { __mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages); if (folio_test_swapbacked(folio)) { __mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages); __mod_lruvec_state(to_vec, NR_SHMEM, nr_pages); } if (folio_mapped(folio)) { __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages); } if (folio_test_dirty(folio)) { struct address_space *mapping = folio_mapping(folio); if (mapping_can_writeback(mapping)) { __mod_lruvec_state(from_vec, NR_FILE_DIRTY, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_DIRTY, nr_pages); } } } if (folio_test_writeback(folio)) { __mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages); __mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages); } /* * All state has been migrated, let's switch to the new memcg. * * It is safe to change page's memcg here because the page * is referenced, charged, isolated, and locked: we can't race * with (un)charging, migration, LRU putback, or anything else * that would rely on a stable page's memory cgroup. * * Note that lock_page_memcg is a memcg lock, not a page lock, * to save space. As soon as we switch page's memory cgroup to a * new memcg that isn't locked, the above state can change * concurrently again. Make sure we're truly done with it. */ smp_mb(); css_get(&to->css); css_put(&from->css); folio->memcg_data = (unsigned long)to; __folio_memcg_unlock(from); ret = 0; nid = folio_nid(folio); local_irq_disable(); mem_cgroup_charge_statistics(to, nr_pages); memcg_check_events(to, nid); mem_cgroup_charge_statistics(from, -nr_pages); memcg_check_events(from, nid); local_irq_enable(); out_unlock: folio_unlock(folio); 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); 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_memcg(page) == 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_memcg(page) == 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; mmap_read_lock(mm); walk_page_range(mm, 0, mm->highest_vm_end, &precharge_walk_ops, NULL); mmap_read_unlock(mm); 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); 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 committed 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--; mem_cgroup_id_get_many(mc.to, 1); /* we fixup other 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(!mmap_read_trylock(mc.mm))) { /* * Someone who are holding the mmap_lock 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); mmap_read_unlock(mc.mm); 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 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 = MAX_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; } memcg_wb_domain_size_changed(memcg); 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 = MAX_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])); seq_printf(m, "oom_group_kill %lu\n", atomic_long_read(&events[MEMCG_OOM_GROUP_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; } #ifdef CONFIG_NUMA static inline unsigned long lruvec_page_state_output(struct lruvec *lruvec, int item) { return lruvec_page_state(lruvec, item) * memcg_page_state_unit(item); } static int memory_numa_stat_show(struct seq_file *m, void *v) { int i; struct mem_cgroup *memcg = mem_cgroup_from_seq(m); mem_cgroup_flush_stats(); for (i = 0; i < ARRAY_SIZE(memory_stats); i++) { int nid; if (memory_stats[i].idx >= NR_VM_NODE_STAT_ITEMS) continue; seq_printf(m, "%s", memory_stats[i].name); for_each_node_state(nid, N_MEMORY) { u64 size; struct lruvec *lruvec; lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); size = lruvec_page_state_output(lruvec, memory_stats[i].idx); seq_printf(m, " N%d=%llu", nid, size); } seq_putc(m, '\n'); } return 0; } #endif 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, }, #ifdef CONFIG_NUMA { .name = "numa_stat", .seq_show = memory_numa_stat_show, }, #endif { .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, .css_rstat_flush = mem_cgroup_css_rstat_flush, .can_attach = mem_cgroup_can_attach, .cancel_attach = mem_cgroup_cancel_attach, .post_attach = mem_cgroup_move_task, .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. * * Check both usage and parent_usage against the respective * protected values. One should imply the other, but they * aren't read atomically - make sure the division is sane. */ if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)) return ep; if (parent_effective > siblings_protected && parent_usage > 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_calculate_protection - 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. */ void mem_cgroup_calculate_protection(struct mem_cgroup *root, struct mem_cgroup *memcg) { unsigned long usage, parent_usage; struct mem_cgroup *parent; if (mem_cgroup_disabled()) return; if (!root) root = root_mem_cgroup; /* * Effective values of the reclaim targets are ignored so they * can be stale. Have a look at mem_cgroup_protection for more * details. * TODO: calculation should be more robust so that we do not need * that special casing. */ if (memcg == root) return; usage = page_counter_read(&memcg->memory); if (!usage) return; parent = parent_mem_cgroup(memcg); /* No parent means a non-hierarchical mode on v1 memcg */ if (!parent) return; if (parent == root) { memcg->memory.emin = READ_ONCE(memcg->memory.min); memcg->memory.elow = READ_ONCE(memcg->memory.low); return; } 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, READ_ONCE(memcg->memory.low), READ_ONCE(parent->memory.elow), atomic_long_read(&parent->memory.children_low_usage))); } static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg, gfp_t gfp) { long nr_pages = folio_nr_pages(folio); int ret; ret = try_charge(memcg, gfp, nr_pages); if (ret) goto out; css_get(&memcg->css); commit_charge(folio, memcg); local_irq_disable(); mem_cgroup_charge_statistics(memcg, nr_pages); memcg_check_events(memcg, folio_nid(folio)); local_irq_enable(); out: return ret; } int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp) { struct mem_cgroup *memcg; int ret; memcg = get_mem_cgroup_from_mm(mm); ret = charge_memcg(folio, memcg, gfp); css_put(&memcg->css); return ret; } /** * mem_cgroup_swapin_charge_page - charge a newly allocated page for swapin * @page: page to charge * @mm: mm context of the victim * @gfp: reclaim mode * @entry: swap entry for which the page is allocated * * This function charges a page allocated for swapin. Please call this before * adding the page to the swapcache. * * Returns 0 on success. Otherwise, an error code is returned. */ int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm, gfp_t gfp, swp_entry_t entry) { struct folio *folio = page_folio(page); struct mem_cgroup *memcg; unsigned short id; int ret; if (mem_cgroup_disabled()) return 0; id = lookup_swap_cgroup_id(entry); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (!memcg || !css_tryget_online(&memcg->css)) memcg = get_mem_cgroup_from_mm(mm); rcu_read_unlock(); ret = charge_memcg(folio, memcg, gfp); css_put(&memcg->css); return ret; } /* * mem_cgroup_swapin_uncharge_swap - uncharge swap slot * @entry: swap entry for which the page is charged * * Call this function after successfully adding the charged page to swapcache. * * Note: This function assumes the page for which swap slot is being uncharged * is order 0 page. */ void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) { /* * Cgroup1's unified memory+swap counter has been charged with the * new swapcache page, finish the transfer by uncharging the swap * slot. The swap slot would also get uncharged when it dies, but * it can stick around indefinitely and we'd count the page twice * the entire time. * * Cgroup2 has separate resource counters for memory and swap, * so this is a non-issue here. Memory and swap charge lifetimes * correspond 1:1 to page and swap slot lifetimes: we charge the * page to memory here, and uncharge swap when the slot is freed. */ if (!mem_cgroup_disabled() && do_memsw_account()) { /* * 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, 1); } } struct uncharge_gather { struct mem_cgroup *memcg; unsigned long nr_memory; unsigned long pgpgout; unsigned long nr_kmem; int nid; }; 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 flags; if (ug->nr_memory) { page_counter_uncharge(&ug->memcg->memory, ug->nr_memory); if (do_memsw_account()) page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory); 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); __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout); __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory); memcg_check_events(ug->memcg, ug->nid); local_irq_restore(flags); /* drop reference from uncharge_folio */ css_put(&ug->memcg->css); } static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug) { long nr_pages; struct mem_cgroup *memcg; struct obj_cgroup *objcg; bool use_objcg = folio_memcg_kmem(folio); VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); /* * Nobody should be changing or seriously looking at * folio memcg or objcg at this point, we have fully * exclusive access to the folio. */ if (use_objcg) { objcg = __folio_objcg(folio); /* * This get matches the put at the end of the function and * kmem pages do not hold memcg references anymore. */ memcg = get_mem_cgroup_from_objcg(objcg); } else { memcg = __folio_memcg(folio); } if (!memcg) return; if (ug->memcg != memcg) { if (ug->memcg) { uncharge_batch(ug); uncharge_gather_clear(ug); } ug->memcg = memcg; ug->nid = folio_nid(folio); /* pairs with css_put in uncharge_batch */ css_get(&memcg->css); } nr_pages = folio_nr_pages(folio); if (use_objcg) { ug->nr_memory += nr_pages; ug->nr_kmem += nr_pages; folio->memcg_data = 0; obj_cgroup_put(objcg); } else { /* LRU pages aren't accounted at the root level */ if (!mem_cgroup_is_root(memcg)) ug->nr_memory += nr_pages; ug->pgpgout++; folio->memcg_data = 0; } css_put(&memcg->css); } void __mem_cgroup_uncharge(struct folio *folio) { struct uncharge_gather ug; /* Don't touch folio->lru of any random page, pre-check: */ if (!folio_memcg(folio)) return; uncharge_gather_clear(&ug); uncharge_folio(folio, &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_charge(). */ void __mem_cgroup_uncharge_list(struct list_head *page_list) { struct uncharge_gather ug; struct folio *folio; uncharge_gather_clear(&ug); list_for_each_entry(folio, page_list, lru) uncharge_folio(folio, &ug); if (ug.memcg) uncharge_batch(&ug); } /** * mem_cgroup_migrate - Charge a folio's replacement. * @old: Currently circulating folio. * @new: Replacement folio. * * Charge @new as a replacement folio for @old. @old will * be uncharged upon free. * * Both folios must be locked, @new->mapping must be set up. */ void mem_cgroup_migrate(struct folio *old, struct folio *new) { struct mem_cgroup *memcg; long nr_pages = folio_nr_pages(new); unsigned long flags; VM_BUG_ON_FOLIO(!folio_test_locked(old), old); VM_BUG_ON_FOLIO(!folio_test_locked(new), new); VM_BUG_ON_FOLIO(folio_test_anon(old) != folio_test_anon(new), new); VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages, new); if (mem_cgroup_disabled()) return; /* Page cache replacement: new folio already charged? */ if (folio_memcg(new)) return; memcg = folio_memcg(old); VM_WARN_ON_ONCE_FOLIO(!memcg, old); if (!memcg) return; /* Force-charge the new page. The old one will be freed soon */ if (!mem_cgroup_is_root(memcg)) { page_counter_charge(&memcg->memory, nr_pages); if (do_memsw_account()) page_counter_charge(&memcg->memsw, nr_pages); } css_get(&memcg->css); commit_charge(new, memcg); local_irq_save(flags); mem_cgroup_charge_statistics(memcg, nr_pages); memcg_check_events(memcg, folio_nid(new)); 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 * @gfp_mask: reclaim mode * * Charges @nr_pages to @memcg. Returns %true if the charge fit within * @memcg's configured limit, %false if it doesn't. */ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages, gfp_t gfp_mask) { 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; } memcg->tcpmem_pressure = 1; if (gfp_mask & __GFP_NOFAIL) { page_counter_charge(&memcg->tcpmem, nr_pages); return true; } return false; } if (try_charge(memcg, gfp_mask, nr_pages) == 0) { mod_memcg_state(memcg, MEMCG_SOCK, nr_pages); return true; } 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; /* * Currently s32 type (can refer to struct batched_lruvec_stat) is * used for per-memcg-per-cpu caching of per-node statistics. In order * to work fine, we should make sure that the overfill threshold can't * exceed S32_MAX / PAGE_SIZE. */ BUILD_BUG_ON(MEMCG_CHARGE_BATCH > S32_MAX / PAGE_SIZE); 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 * @folio: folio whose memsw charge to transfer * @entry: swap entry to move the charge to * * Transfer the memsw charge of @folio to @entry. */ void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry) { struct mem_cgroup *memcg, *swap_memcg; unsigned int nr_entries; unsigned short oldid; VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); VM_BUG_ON_FOLIO(folio_ref_count(folio), folio); if (mem_cgroup_disabled()) return; if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; memcg = folio_memcg(folio); VM_WARN_ON_ONCE_FOLIO(!memcg, folio); 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 = folio_nr_pages(folio); /* 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_FOLIO(oldid, folio); mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries); folio->memcg_data = 0; if (!mem_cgroup_is_root(memcg)) page_counter_uncharge(&memcg->memory, nr_entries); if (!cgroup_memory_noswap && 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, -nr_entries); memcg_check_events(memcg, folio_nid(folio)); css_put(&memcg->css); } /** * __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 = thp_nr_pages(page); struct page_counter *counter; struct mem_cgroup *memcg; unsigned short oldid; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; memcg = page_memcg(page); VM_WARN_ON_ONCE_PAGE(!memcg, page); if (!memcg) return 0; if (!entry.val) { memcg_memory_event(memcg, MEMCG_SWAP_FAIL); return 0; } memcg = mem_cgroup_id_get_online(memcg); if (!cgroup_memory_noswap && !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; id = swap_cgroup_record(entry, 0, nr_pages); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg) { if (!cgroup_memory_noswap && !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 (cgroup_memory_noswap || !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 (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) return false; memcg = page_memcg(page); 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; } static int __init setup_swap_account(char *s) { if (!strcmp(s, "1")) cgroup_memory_noswap = false; else if (!strcmp(s, "0")) cgroup_memory_noswap = true; return 1; } __setup("swapaccount=", setup_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_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 */ }; /* * If mem_cgroup_swap_init() is implemented as a subsys_initcall() * instead of a core_initcall(), this could mean cgroup_memory_noswap still * remains set to false even when memcg is disabled via "cgroup_disable=memory" * boot parameter. This may result in premature OOPS inside * mem_cgroup_get_nr_swap_pages() function in corner cases. */ static int __init mem_cgroup_swap_init(void) { /* No memory control -> no swap control */ if (mem_cgroup_disabled()) cgroup_memory_noswap = true; if (cgroup_memory_noswap) return 0; WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files)); WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files)); return 0; } core_initcall(mem_cgroup_swap_init); #endif /* CONFIG_MEMCG_SWAP */