diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 6784 |
1 files changed, 6784 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c new file mode 100644 index 000000000..f3aa6e621 --- /dev/null +++ b/mm/memcontrol.c @@ -0,0 +1,6784 @@ +/* memcontrol.c - Memory Controller + * + * Copyright IBM Corporation, 2007 + * Author Balbir Singh <balbir@linux.vnet.ibm.com> + * + * Copyright 2007 OpenVZ SWsoft Inc + * Author: Pavel Emelianov <xemul@openvz.org> + * + * 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 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/page_counter.h> +#include <linux/memcontrol.h> +#include <linux/cgroup.h> +#include <linux/mm.h> +#include <linux/sched/mm.h> +#include <linux/shmem_fs.h> +#include <linux/hugetlb.h> +#include <linux/pagemap.h> +#include <linux/smp.h> +#include <linux/page-flags.h> +#include <linux/backing-dev.h> +#include <linux/bit_spinlock.h> +#include <linux/rcupdate.h> +#include <linux/limits.h> +#include <linux/export.h> +#include <linux/mutex.h> +#include <linux/rbtree.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/spinlock.h> +#include <linux/eventfd.h> +#include <linux/poll.h> +#include <linux/sort.h> +#include <linux/fs.h> +#include <linux/seq_file.h> +#include <linux/vmpressure.h> +#include <linux/mm_inline.h> +#include <linux/swap_cgroup.h> +#include <linux/cpu.h> +#include <linux/oom.h> +#include <linux/lockdep.h> +#include <linux/file.h> +#include <linux/tracehook.h> +#include "internal.h" +#include <net/sock.h> +#include <net/ip.h> +#include "slab.h" + +#include <linux/uaccess.h> + +#include <trace/events/vmscan.h> + +struct cgroup_subsys memory_cgrp_subsys __read_mostly; +EXPORT_SYMBOL(memory_cgrp_subsys); + +struct mem_cgroup *root_mem_cgroup __read_mostly; + +#define MEM_CGROUP_RECLAIM_RETRIES 5 + +/* Socket memory accounting disabled? */ +static bool cgroup_memory_nosocket; + +/* Kernel memory accounting disabled? */ +static bool cgroup_memory_nokmem; + +/* Whether the swap controller is active */ +#ifdef CONFIG_MEMCG_SWAP +int do_swap_account __read_mostly; +#else +#define do_swap_account 0 +#endif + +/* Whether legacy memory+swap accounting is active */ +static bool do_memsw_account(void) +{ + return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account; +} + +static const char *const mem_cgroup_lru_names[] = { + "inactive_anon", + "active_anon", + "inactive_file", + "active_file", + "unevictable", +}; + +#define THRESHOLDS_EVENTS_TARGET 128 +#define SOFTLIMIT_EVENTS_TARGET 1024 +#define NUMAINFO_EVENTS_TARGET 1024 + +/* + * Cgroups above their limits are maintained in a RB-Tree, independent of + * their hierarchy representation + */ + +struct mem_cgroup_tree_per_node { + struct rb_root rb_root; + struct rb_node *rb_rightmost; + spinlock_t lock; +}; + +struct mem_cgroup_tree { + struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES]; +}; + +static struct mem_cgroup_tree soft_limit_tree __read_mostly; + +/* for OOM */ +struct mem_cgroup_eventfd_list { + struct list_head list; + struct eventfd_ctx *eventfd; +}; + +/* + * cgroup_event represents events which userspace want to receive. + */ +struct mem_cgroup_event { + /* + * memcg which the event belongs to. + */ + struct mem_cgroup *memcg; + /* + * eventfd to signal userspace about the event. + */ + struct eventfd_ctx *eventfd; + /* + * Each of these stored in a list by the cgroup. + */ + struct list_head list; + /* + * register_event() callback will be used to add new userspace + * waiter for changes related to this event. Use eventfd_signal() + * on eventfd to send notification to userspace. + */ + int (*register_event)(struct mem_cgroup *memcg, + struct eventfd_ctx *eventfd, const char *args); + /* + * unregister_event() callback will be called when userspace closes + * the eventfd or on cgroup removing. This callback must be set, + * if you want provide notification functionality. + */ + void (*unregister_event)(struct mem_cgroup *memcg, + struct eventfd_ctx *eventfd); + /* + * All fields below needed to unregister event when + * userspace closes eventfd. + */ + poll_table pt; + wait_queue_head_t *wqh; + wait_queue_entry_t wait; + struct work_struct remove; +}; + +static void mem_cgroup_threshold(struct mem_cgroup *memcg); +static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); + +/* Stuffs for move charges at task migration. */ +/* + * Types of charges to be moved. + */ +#define MOVE_ANON 0x1U +#define MOVE_FILE 0x2U +#define MOVE_MASK (MOVE_ANON | MOVE_FILE) + +/* "mc" and its members are protected by cgroup_mutex */ +static struct move_charge_struct { + spinlock_t lock; /* for from, to */ + struct mm_struct *mm; + struct mem_cgroup *from; + struct mem_cgroup *to; + unsigned long flags; + unsigned long precharge; + unsigned long moved_charge; + unsigned long moved_swap; + struct task_struct *moving_task; /* a task moving charges */ + wait_queue_head_t waitq; /* a waitq for other context */ +} mc = { + .lock = __SPIN_LOCK_UNLOCKED(mc.lock), + .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), +}; + +/* + * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft + * limit reclaim to prevent infinite loops, if they ever occur. + */ +#define MEM_CGROUP_MAX_RECLAIM_LOOPS 100 +#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2 + +enum charge_type { + MEM_CGROUP_CHARGE_TYPE_CACHE = 0, + MEM_CGROUP_CHARGE_TYPE_ANON, + MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */ + MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */ + NR_CHARGE_TYPE, +}; + +/* for encoding cft->private value on file */ +enum res_type { + _MEM, + _MEMSWAP, + _OOM_TYPE, + _KMEM, + _TCP, +}; + +#define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val)) +#define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff) +#define MEMFILE_ATTR(val) ((val) & 0xffff) +/* Used for OOM nofiier */ +#define OOM_CONTROL (0) + +/* + * Iteration constructs for visiting all cgroups (under a tree). If + * loops are exited prematurely (break), mem_cgroup_iter_break() must + * be used for reference counting. + */ +#define for_each_mem_cgroup_tree(iter, root) \ + for (iter = mem_cgroup_iter(root, NULL, NULL); \ + iter != NULL; \ + iter = mem_cgroup_iter(root, iter, NULL)) + +#define for_each_mem_cgroup(iter) \ + for (iter = mem_cgroup_iter(NULL, NULL, NULL); \ + iter != NULL; \ + iter = mem_cgroup_iter(NULL, iter, NULL)) + +static inline bool should_force_charge(void) +{ + return tsk_is_oom_victim(current) || fatal_signal_pending(current) || + (current->flags & PF_EXITING); +} + +/* Some nice accessors for the vmpressure. */ +struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg) +{ + if (!memcg) + memcg = root_mem_cgroup; + return &memcg->vmpressure; +} + +struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr) +{ + return &container_of(vmpr, struct mem_cgroup, vmpressure)->css; +} + +#ifdef CONFIG_MEMCG_KMEM +/* + * This will be the memcg's index in each cache's ->memcg_params.memcg_caches. + * The main reason for not using cgroup id for this: + * this works better in sparse environments, where we have a lot of memcgs, + * but only a few kmem-limited. Or also, if we have, for instance, 200 + * memcgs, and none but the 200th is kmem-limited, we'd have to have a + * 200 entry array for that. + * + * The current size of the caches array is stored in memcg_nr_cache_ids. It + * will double each time we have to increase it. + */ +static DEFINE_IDA(memcg_cache_ida); +int memcg_nr_cache_ids; + +/* Protects memcg_nr_cache_ids */ +static DECLARE_RWSEM(memcg_cache_ids_sem); + +void memcg_get_cache_ids(void) +{ + down_read(&memcg_cache_ids_sem); +} + +void memcg_put_cache_ids(void) +{ + up_read(&memcg_cache_ids_sem); +} + +/* + * MIN_SIZE is different than 1, because we would like to avoid going through + * the alloc/free process all the time. In a small machine, 4 kmem-limited + * cgroups is a reasonable guess. In the future, it could be a parameter or + * tunable, but that is strictly not necessary. + * + * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get + * this constant directly from cgroup, but it is understandable that this is + * better kept as an internal representation in cgroup.c. In any case, the + * cgrp_id space is not getting any smaller, and we don't have to necessarily + * increase ours as well if it increases. + */ +#define MEMCG_CACHES_MIN_SIZE 4 +#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX + +/* + * A lot of the calls to the cache allocation functions are expected to be + * inlined by the compiler. Since the calls to memcg_kmem_get_cache are + * conditional to this static branch, we'll have to allow modules that does + * kmem_cache_alloc and the such to see this symbol as well + */ +DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key); +EXPORT_SYMBOL(memcg_kmem_enabled_key); + +struct workqueue_struct *memcg_kmem_cache_wq; + +static int memcg_shrinker_map_size; +static DEFINE_MUTEX(memcg_shrinker_map_mutex); + +static void memcg_free_shrinker_map_rcu(struct rcu_head *head) +{ + kvfree(container_of(head, struct memcg_shrinker_map, rcu)); +} + +static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg, + int size, int old_size) +{ + struct memcg_shrinker_map *new, *old; + int nid; + + lockdep_assert_held(&memcg_shrinker_map_mutex); + + for_each_node(nid) { + old = rcu_dereference_protected( + mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true); + /* Not yet online memcg */ + if (!old) + return 0; + + new = kvmalloc(sizeof(*new) + size, GFP_KERNEL); + if (!new) + return -ENOMEM; + + /* Set all old bits, clear all new bits */ + memset(new->map, (int)0xff, old_size); + memset((void *)new->map + old_size, 0, size - old_size); + + rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new); + call_rcu(&old->rcu, memcg_free_shrinker_map_rcu); + } + + return 0; +} + +static void memcg_free_shrinker_maps(struct mem_cgroup *memcg) +{ + struct mem_cgroup_per_node *pn; + struct memcg_shrinker_map *map; + int nid; + + if (mem_cgroup_is_root(memcg)) + return; + + for_each_node(nid) { + pn = mem_cgroup_nodeinfo(memcg, nid); + map = rcu_dereference_protected(pn->shrinker_map, true); + if (map) + kvfree(map); + rcu_assign_pointer(pn->shrinker_map, NULL); + } +} + +static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) +{ + struct memcg_shrinker_map *map; + int nid, size, ret = 0; + + if (mem_cgroup_is_root(memcg)) + return 0; + + mutex_lock(&memcg_shrinker_map_mutex); + size = memcg_shrinker_map_size; + for_each_node(nid) { + map = kvzalloc(sizeof(*map) + size, GFP_KERNEL); + if (!map) { + memcg_free_shrinker_maps(memcg); + ret = -ENOMEM; + break; + } + rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map); + } + mutex_unlock(&memcg_shrinker_map_mutex); + + return ret; +} + +int memcg_expand_shrinker_maps(int new_id) +{ + int size, old_size, ret = 0; + struct mem_cgroup *memcg; + + size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); + old_size = memcg_shrinker_map_size; + if (size <= old_size) + return 0; + + mutex_lock(&memcg_shrinker_map_mutex); + if (!root_mem_cgroup) + goto unlock; + + for_each_mem_cgroup(memcg) { + if (mem_cgroup_is_root(memcg)) + continue; + ret = memcg_expand_one_shrinker_map(memcg, size, old_size); + if (ret) { + mem_cgroup_iter_break(NULL, memcg); + goto unlock; + } + } +unlock: + if (!ret) + memcg_shrinker_map_size = size; + mutex_unlock(&memcg_shrinker_map_mutex); + return ret; +} + +void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) +{ + if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) { + struct memcg_shrinker_map *map; + + rcu_read_lock(); + map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map); + /* Pairs with smp mb in shrink_slab() */ + smp_mb__before_atomic(); + set_bit(shrinker_id, map->map); + rcu_read_unlock(); + } +} + +#else /* CONFIG_MEMCG_KMEM */ +static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) +{ + return 0; +} +static void memcg_free_shrinker_maps(struct mem_cgroup *memcg) { } +#endif /* CONFIG_MEMCG_KMEM */ + +/** + * mem_cgroup_css_from_page - css of the memcg associated with a page + * @page: page of interest + * + * If memcg is bound to the default hierarchy, css of the memcg associated + * with @page is returned. The returned css remains associated with @page + * until it is released. + * + * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup + * is returned. + */ +struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page) +{ + struct mem_cgroup *memcg; + + memcg = page->mem_cgroup; + + if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) + memcg = root_mem_cgroup; + + return &memcg->css; +} + +/** + * page_cgroup_ino - return inode number of the memcg a page is charged to + * @page: the page + * + * Look up the closest online ancestor of the memory cgroup @page is charged to + * and return its inode number or 0 if @page is not charged to any cgroup. It + * is safe to call this function without holding a reference to @page. + * + * Note, this function is inherently racy, because there is nothing to prevent + * the cgroup inode from getting torn down and potentially reallocated a moment + * after page_cgroup_ino() returns, so it only should be used by callers that + * do not care (such as procfs interfaces). + */ +ino_t page_cgroup_ino(struct page *page) +{ + struct mem_cgroup *memcg; + unsigned long ino = 0; + + rcu_read_lock(); + memcg = READ_ONCE(page->mem_cgroup); + while (memcg && !(memcg->css.flags & CSS_ONLINE)) + memcg = parent_mem_cgroup(memcg); + if (memcg) + ino = cgroup_ino(memcg->css.cgroup); + rcu_read_unlock(); + return ino; +} + +static struct mem_cgroup_per_node * +mem_cgroup_page_nodeinfo(struct mem_cgroup *memcg, struct page *page) +{ + int nid = page_to_nid(page); + + return memcg->nodeinfo[nid]; +} + +static struct mem_cgroup_tree_per_node * +soft_limit_tree_node(int nid) +{ + return soft_limit_tree.rb_tree_per_node[nid]; +} + +static struct mem_cgroup_tree_per_node * +soft_limit_tree_from_page(struct page *page) +{ + int nid = page_to_nid(page); + + return soft_limit_tree.rb_tree_per_node[nid]; +} + +static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, + struct mem_cgroup_tree_per_node *mctz, + unsigned long new_usage_in_excess) +{ + struct rb_node **p = &mctz->rb_root.rb_node; + struct rb_node *parent = NULL; + struct mem_cgroup_per_node *mz_node; + bool rightmost = true; + + if (mz->on_tree) + return; + + mz->usage_in_excess = new_usage_in_excess; + if (!mz->usage_in_excess) + return; + while (*p) { + parent = *p; + mz_node = rb_entry(parent, struct mem_cgroup_per_node, + tree_node); + if (mz->usage_in_excess < mz_node->usage_in_excess) { + p = &(*p)->rb_left; + rightmost = false; + } + + /* + * We can't avoid mem cgroups that are over their soft + * limit by the same amount + */ + else if (mz->usage_in_excess >= mz_node->usage_in_excess) + p = &(*p)->rb_right; + } + + if (rightmost) + mctz->rb_rightmost = &mz->tree_node; + + rb_link_node(&mz->tree_node, parent, p); + rb_insert_color(&mz->tree_node, &mctz->rb_root); + mz->on_tree = true; +} + +static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, + struct mem_cgroup_tree_per_node *mctz) +{ + if (!mz->on_tree) + return; + + if (&mz->tree_node == mctz->rb_rightmost) + mctz->rb_rightmost = rb_prev(&mz->tree_node); + + rb_erase(&mz->tree_node, &mctz->rb_root); + mz->on_tree = false; +} + +static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, + struct mem_cgroup_tree_per_node *mctz) +{ + unsigned long flags; + + spin_lock_irqsave(&mctz->lock, flags); + __mem_cgroup_remove_exceeded(mz, mctz); + spin_unlock_irqrestore(&mctz->lock, flags); +} + +static unsigned long soft_limit_excess(struct mem_cgroup *memcg) +{ + unsigned long nr_pages = page_counter_read(&memcg->memory); + unsigned long soft_limit = READ_ONCE(memcg->soft_limit); + unsigned long excess = 0; + + if (nr_pages > soft_limit) + excess = nr_pages - soft_limit; + + return excess; +} + +static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page) +{ + unsigned long excess; + struct mem_cgroup_per_node *mz; + struct mem_cgroup_tree_per_node *mctz; + + mctz = soft_limit_tree_from_page(page); + if (!mctz) + return; + /* + * Necessary to update all ancestors when hierarchy is used. + * because their event counter is not touched. + */ + for (; memcg; memcg = parent_mem_cgroup(memcg)) { + mz = mem_cgroup_page_nodeinfo(memcg, page); + excess = soft_limit_excess(memcg); + /* + * We have to update the tree if mz is on RB-tree or + * mem is over its softlimit. + */ + if (excess || mz->on_tree) { + unsigned long flags; + + spin_lock_irqsave(&mctz->lock, flags); + /* if on-tree, remove it */ + if (mz->on_tree) + __mem_cgroup_remove_exceeded(mz, mctz); + /* + * Insert again. mz->usage_in_excess will be updated. + * If excess is 0, no tree ops. + */ + __mem_cgroup_insert_exceeded(mz, mctz, excess); + spin_unlock_irqrestore(&mctz->lock, flags); + } + } +} + +static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) +{ + struct mem_cgroup_tree_per_node *mctz; + struct mem_cgroup_per_node *mz; + int nid; + + for_each_node(nid) { + mz = mem_cgroup_nodeinfo(memcg, nid); + mctz = soft_limit_tree_node(nid); + if (mctz) + mem_cgroup_remove_exceeded(mz, mctz); + } +} + +static struct mem_cgroup_per_node * +__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) +{ + struct mem_cgroup_per_node *mz; + +retry: + mz = NULL; + if (!mctz->rb_rightmost) + goto done; /* Nothing to reclaim from */ + + mz = rb_entry(mctz->rb_rightmost, + struct mem_cgroup_per_node, tree_node); + /* + * Remove the node now but someone else can add it back, + * we will to add it back at the end of reclaim to its correct + * position in the tree. + */ + __mem_cgroup_remove_exceeded(mz, mctz); + if (!soft_limit_excess(mz->memcg) || + !css_tryget_online(&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; +} + +static unsigned long memcg_sum_events(struct mem_cgroup *memcg, + int event) +{ + return atomic_long_read(&memcg->events[event]); +} + +static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, + struct page *page, + bool compound, int nr_pages) +{ + /* + * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is + * counted as CACHE even if it's on ANON LRU. + */ + if (PageAnon(page)) + __mod_memcg_state(memcg, MEMCG_RSS, nr_pages); + else { + __mod_memcg_state(memcg, MEMCG_CACHE, nr_pages); + if (PageSwapBacked(page)) + __mod_memcg_state(memcg, NR_SHMEM, nr_pages); + } + + if (compound) { + VM_BUG_ON_PAGE(!PageTransHuge(page), page); + __mod_memcg_state(memcg, MEMCG_RSS_HUGE, nr_pages); + } + + /* pagein of a big page is an event. So, ignore page size */ + if (nr_pages > 0) + __count_memcg_events(memcg, PGPGIN, 1); + else { + __count_memcg_events(memcg, PGPGOUT, 1); + nr_pages = -nr_pages; /* for event */ + } + + __this_cpu_add(memcg->stat_cpu->nr_page_events, nr_pages); +} + +unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, + int nid, unsigned int lru_mask) +{ + struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg); + unsigned long nr = 0; + enum lru_list lru; + + VM_BUG_ON((unsigned)nid >= nr_node_ids); + + for_each_lru(lru) { + if (!(BIT(lru) & lru_mask)) + continue; + nr += mem_cgroup_get_lru_size(lruvec, lru); + } + return nr; +} + +static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg, + unsigned int lru_mask) +{ + unsigned long nr = 0; + int nid; + + for_each_node_state(nid, N_MEMORY) + nr += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask); + return nr; +} + +static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, + enum mem_cgroup_events_target target) +{ + unsigned long val, next; + + val = __this_cpu_read(memcg->stat_cpu->nr_page_events); + next = __this_cpu_read(memcg->stat_cpu->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; + case MEM_CGROUP_TARGET_NUMAINFO: + next = val + NUMAINFO_EVENTS_TARGET; + break; + default: + break; + } + __this_cpu_write(memcg->stat_cpu->targets[target], next); + return true; + } + return false; +} + +/* + * Check events in order. + * + */ +static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) +{ + /* threshold event is triggered in finer grain than soft limit */ + if (unlikely(mem_cgroup_event_ratelimit(memcg, + MEM_CGROUP_TARGET_THRESH))) { + bool do_softlimit; + bool do_numainfo __maybe_unused; + + do_softlimit = mem_cgroup_event_ratelimit(memcg, + MEM_CGROUP_TARGET_SOFTLIMIT); +#if MAX_NUMNODES > 1 + do_numainfo = mem_cgroup_event_ratelimit(memcg, + MEM_CGROUP_TARGET_NUMAINFO); +#endif + mem_cgroup_threshold(memcg); + if (unlikely(do_softlimit)) + mem_cgroup_update_tree(memcg, page); +#if MAX_NUMNODES > 1 + if (unlikely(do_numainfo)) + atomic_inc(&memcg->numainfo_events); +#endif + } +} + +struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) +{ + /* + * mm_update_next_owner() may clear mm->owner to NULL + * if it races with swapoff, page migration, etc. + * So this can be called with p == NULL. + */ + if (unlikely(!p)) + return NULL; + + return mem_cgroup_from_css(task_css(p, memory_cgrp_id)); +} +EXPORT_SYMBOL(mem_cgroup_from_task); + +/** + * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg. + * @mm: mm from which memcg should be extracted. It can be NULL. + * + * Obtain a reference on mm->memcg and returns it if successful. Otherwise + * root_mem_cgroup is returned. However if mem_cgroup is disabled, NULL is + * returned. + */ +struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) +{ + struct mem_cgroup *memcg; + + if (mem_cgroup_disabled()) + return NULL; + + rcu_read_lock(); + do { + /* + * Page cache insertions can happen withou an + * actual mm context, e.g. during disk probing + * on boot, loopback IO, acct() writes etc. + */ + if (unlikely(!mm)) + memcg = root_mem_cgroup; + else { + memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); + if (unlikely(!memcg)) + memcg = root_mem_cgroup; + } + } while (!css_tryget(&memcg->css)); + rcu_read_unlock(); + return memcg; +} +EXPORT_SYMBOL(get_mem_cgroup_from_mm); + +/** + * get_mem_cgroup_from_page: Obtain a reference on given page's memcg. + * @page: page from which memcg should be extracted. + * + * Obtain a reference on page->memcg and returns it if successful. Otherwise + * root_mem_cgroup is returned. + */ +struct mem_cgroup *get_mem_cgroup_from_page(struct page *page) +{ + struct mem_cgroup *memcg = page->mem_cgroup; + + if (mem_cgroup_disabled()) + return NULL; + + rcu_read_lock(); + if (!memcg || !css_tryget_online(&memcg->css)) + memcg = root_mem_cgroup; + rcu_read_unlock(); + return memcg; +} +EXPORT_SYMBOL(get_mem_cgroup_from_page); + +/** + * If current->active_memcg is non-NULL, do not fallback to current->mm->memcg. + */ +static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void) +{ + if (unlikely(current->active_memcg)) { + struct mem_cgroup *memcg = root_mem_cgroup; + + rcu_read_lock(); + if (css_tryget_online(¤t->active_memcg->css)) + memcg = current->active_memcg; + rcu_read_unlock(); + return memcg; + } + return get_mem_cgroup_from_mm(current->mm); +} + +/** + * mem_cgroup_iter - iterate over memory cgroup hierarchy + * @root: hierarchy root + * @prev: previously returned memcg, NULL on first invocation + * @reclaim: cookie for shared reclaim walks, NULL for full walks + * + * Returns references to children of the hierarchy below @root, or + * @root itself, or %NULL after a full round-trip. + * + * Caller must pass the return value in @prev on subsequent + * invocations for reference counting, or use mem_cgroup_iter_break() + * to cancel a hierarchy walk before the round-trip is complete. + * + * Reclaimers can specify a node and a priority level in @reclaim to + * divide up the memcgs in the hierarchy among all concurrent + * reclaimers operating on the same node and priority. + */ +struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, + struct mem_cgroup *prev, + struct mem_cgroup_reclaim_cookie *reclaim) +{ + struct mem_cgroup_reclaim_iter *uninitialized_var(iter); + struct cgroup_subsys_state *css = NULL; + struct mem_cgroup *memcg = NULL; + struct mem_cgroup *pos = NULL; + + if (mem_cgroup_disabled()) + return NULL; + + if (!root) + root = root_mem_cgroup; + + if (prev && !reclaim) + pos = prev; + + if (!root->use_hierarchy && root != root_mem_cgroup) { + if (prev) + goto out; + return root; + } + + rcu_read_lock(); + + if (reclaim) { + struct mem_cgroup_per_node *mz; + + mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id); + iter = &mz->iter[reclaim->priority]; + + if (prev && reclaim->generation != iter->generation) + goto out_unlock; + + while (1) { + pos = READ_ONCE(iter->position); + if (!pos || css_tryget(&pos->css)) + break; + /* + * css reference reached zero, so iter->position will + * be cleared by ->css_released. However, we should not + * rely on this happening soon, because ->css_released + * is called from a work queue, and by busy-waiting we + * might block it. So we clear iter->position right + * away. + */ + (void)cmpxchg(&iter->position, pos, NULL); + } + } + + if (pos) + css = &pos->css; + + for (;;) { + css = css_next_descendant_pre(css, &root->css); + if (!css) { + /* + * Reclaimers share the hierarchy walk, and a + * new one might jump in right at the end of + * the hierarchy - make sure they see at least + * one group and restart from the beginning. + */ + if (!prev) + continue; + break; + } + + /* + * Verify the css and acquire a reference. The root + * is provided by the caller, so we know it's alive + * and kicking, and don't take an extra reference. + */ + memcg = mem_cgroup_from_css(css); + + if (css == &root->css) + break; + + if (css_tryget(css)) + break; + + memcg = NULL; + } + + if (reclaim) { + /* + * The position could have already been updated by a competing + * thread, so check that the value hasn't changed since we read + * it to avoid reclaiming from the same cgroup twice. + */ + (void)cmpxchg(&iter->position, pos, memcg); + + if (pos) + css_put(&pos->css); + + if (!memcg) + iter->generation++; + else if (!prev) + reclaim->generation = iter->generation; + } + +out_unlock: + rcu_read_unlock(); +out: + if (prev && prev != root) + css_put(&prev->css); + + return memcg; +} + +/** + * mem_cgroup_iter_break - abort a hierarchy walk prematurely + * @root: hierarchy root + * @prev: last visited hierarchy member as returned by mem_cgroup_iter() + */ +void mem_cgroup_iter_break(struct mem_cgroup *root, + struct mem_cgroup *prev) +{ + if (!root) + root = root_mem_cgroup; + if (prev && prev != root) + css_put(&prev->css); +} + +static void __invalidate_reclaim_iterators(struct mem_cgroup *from, + struct mem_cgroup *dead_memcg) +{ + struct mem_cgroup_reclaim_iter *iter; + struct mem_cgroup_per_node *mz; + int nid; + int i; + + for_each_node(nid) { + mz = mem_cgroup_nodeinfo(from, nid); + for (i = 0; i <= DEF_PRIORITY; i++) { + iter = &mz->iter[i]; + 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, 0, &it); + while (!ret && (task = css_task_iter_next(&it))) + ret = fn(task, arg); + css_task_iter_end(&it); + if (ret) { + mem_cgroup_iter_break(memcg, iter); + break; + } + } + return ret; +} + +/** + * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page + * @page: the page + * @pgdat: pgdat of the page + * + * This function is only safe when following the LRU page isolation + * and putback protocol: the LRU lock must be held, and the page must + * either be PageLRU() or the caller must have isolated/allocated it. + */ +struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat) +{ + struct mem_cgroup_per_node *mz; + struct mem_cgroup *memcg; + struct lruvec *lruvec; + + if (mem_cgroup_disabled()) { + lruvec = &pgdat->lruvec; + goto out; + } + + memcg = page->mem_cgroup; + /* + * Swapcache readahead pages are added to the LRU - and + * possibly migrated - before they are charged. + */ + if (!memcg) + memcg = root_mem_cgroup; + + mz = mem_cgroup_page_nodeinfo(memcg, page); + lruvec = &mz->lruvec; +out: + /* + * Since a node can be onlined after the mem_cgroup was created, + * we have to be prepared to initialize lruvec->zone here; + * and if offlined then reonlined, we need to reinitialize it. + */ + if (unlikely(lruvec->pgdat != pgdat)) + lruvec->pgdat = pgdat; + return lruvec; +} + +/** + * mem_cgroup_update_lru_size - account for adding or removing an lru page + * @lruvec: mem_cgroup per zone lru vector + * @lru: index of lru list the page is sitting on + * @zid: zone id of the accounted pages + * @nr_pages: positive when adding or negative when removing + * + * This function must be called under lru_lock, just before a page is added + * to or just after a page is removed from an lru list (that ordering being + * so as to allow it to check that lru_size 0 is consistent with list_empty). + */ +void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, + int zid, int nr_pages) +{ + struct mem_cgroup_per_node *mz; + unsigned long *lru_size; + long size; + + if (mem_cgroup_disabled()) + return; + + mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec); + lru_size = &mz->lru_zone_size[zid][lru]; + + if (nr_pages < 0) + *lru_size += nr_pages; + + size = *lru_size; + if (WARN_ONCE(size < 0, + "%s(%p, %d, %d): lru_size %ld\n", + __func__, lruvec, lru, nr_pages, size)) { + VM_BUG_ON(1); + *lru_size = 0; + } + + if (nr_pages > 0) + *lru_size += nr_pages; +} + +bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg) +{ + struct mem_cgroup *task_memcg; + struct task_struct *p; + bool ret; + + p = find_lock_task_mm(task); + if (p) { + task_memcg = get_mem_cgroup_from_mm(p->mm); + task_unlock(p); + } else { + /* + * All threads may have already detached their mm's, but the oom + * killer still needs to detect if they have already been oom + * killed to prevent needlessly killing additional tasks. + */ + rcu_read_lock(); + task_memcg = mem_cgroup_from_task(task); + css_get(&task_memcg->css); + rcu_read_unlock(); + } + ret = mem_cgroup_is_descendant(task_memcg, memcg); + css_put(&task_memcg->css); + return ret; +} + +/** + * mem_cgroup_margin - calculate chargeable space of a memory cgroup + * @memcg: the memory cgroup + * + * Returns the maximum amount of memory @mem can be charged with, in + * pages. + */ +static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg) +{ + unsigned long margin = 0; + unsigned long count; + unsigned long limit; + + count = page_counter_read(&memcg->memory); + limit = READ_ONCE(memcg->memory.max); + if (count < limit) + margin = limit - count; + + if (do_memsw_account()) { + count = page_counter_read(&memcg->memsw); + limit = READ_ONCE(memcg->memsw.max); + if (count <= limit) + margin = min(margin, limit - count); + else + margin = 0; + } + + return margin; +} + +/* + * A routine for checking "mem" is under move_account() or not. + * + * Checking a cgroup is mc.from or mc.to or under hierarchy of + * moving cgroups. This is for waiting at high-memory pressure + * caused by "move". + */ +static bool mem_cgroup_under_move(struct mem_cgroup *memcg) +{ + struct mem_cgroup *from; + struct mem_cgroup *to; + bool ret = false; + /* + * Unlike task_move routines, we access mc.to, mc.from not under + * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. + */ + spin_lock(&mc.lock); + from = mc.from; + to = mc.to; + if (!from) + goto unlock; + + ret = mem_cgroup_is_descendant(from, memcg) || + mem_cgroup_is_descendant(to, memcg); +unlock: + spin_unlock(&mc.lock); + return ret; +} + +static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) +{ + if (mc.moving_task && current != mc.moving_task) { + if (mem_cgroup_under_move(memcg)) { + DEFINE_WAIT(wait); + prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); + /* moving charge context might have finished. */ + if (mc.moving_task) + schedule(); + finish_wait(&mc.waitq, &wait); + return true; + } + } + return false; +} + +static const unsigned int memcg1_stats[] = { + MEMCG_CACHE, + MEMCG_RSS, + MEMCG_RSS_HUGE, + NR_SHMEM, + NR_FILE_MAPPED, + NR_FILE_DIRTY, + NR_WRITEBACK, + MEMCG_SWAP, +}; + +static const char *const memcg1_stat_names[] = { + "cache", + "rss", + "rss_huge", + "shmem", + "mapped_file", + "dirty", + "writeback", + "swap", +}; + +#define K(x) ((x) << (PAGE_SHIFT-10)) +/** + * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller. + * @memcg: The memory cgroup that went over limit + * @p: Task that is going to be killed + * + * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is + * enabled + */ +void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) +{ + struct mem_cgroup *iter; + unsigned int i; + + rcu_read_lock(); + + if (p) { + pr_info("Task in "); + pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id)); + pr_cont(" killed as a result of limit of "); + } else { + pr_info("Memory limit reached of cgroup "); + } + + pr_cont_cgroup_path(memcg->css.cgroup); + pr_cont("\n"); + + rcu_read_unlock(); + + pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n", + K((u64)page_counter_read(&memcg->memory)), + K((u64)memcg->memory.max), memcg->memory.failcnt); + 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); + + for_each_mem_cgroup_tree(iter, memcg) { + pr_info("Memory cgroup stats for "); + pr_cont_cgroup_path(iter->css.cgroup); + pr_cont(":"); + + for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { + if (memcg1_stats[i] == MEMCG_SWAP && !do_swap_account) + continue; + pr_cont(" %s:%luKB", memcg1_stat_names[i], + K(memcg_page_state(iter, memcg1_stats[i]))); + } + + for (i = 0; i < NR_LRU_LISTS; i++) + pr_cont(" %s:%luKB", mem_cgroup_lru_names[i], + K(mem_cgroup_nr_lru_pages(iter, BIT(i)))); + + pr_cont("\n"); + } +} + +/* + * Return the memory (and swap, if configured) limit for a memcg. + */ +unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) +{ + unsigned long max; + + max = memcg->memory.max; + if (mem_cgroup_swappiness(memcg)) { + unsigned long memsw_max; + unsigned long swap_max; + + memsw_max = memcg->memsw.max; + swap_max = memcg->swap.max; + swap_max = min(swap_max, (unsigned long)total_swap_pages); + max = min(max + swap_max, memsw_max); + } + return max; +} + +static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, + int order) +{ + struct oom_control oc = { + .zonelist = NULL, + .nodemask = NULL, + .memcg = memcg, + .gfp_mask = gfp_mask, + .order = order, + }; + bool ret; + + if (mutex_lock_killable(&oom_lock)) + return true; + /* + * A few threads which were not waiting at mutex_lock_killable() can + * fail to bail out. Therefore, check again after holding oom_lock. + */ + ret = should_force_charge() || out_of_memory(&oc); + mutex_unlock(&oom_lock); + return ret; +} + +#if MAX_NUMNODES > 1 + +/** + * test_mem_cgroup_node_reclaimable + * @memcg: the target memcg + * @nid: the node ID to be checked. + * @noswap : specify true here if the user wants flle only information. + * + * This function returns whether the specified memcg contains any + * reclaimable pages on a node. Returns true if there are any reclaimable + * pages in the node. + */ +static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg, + int nid, bool noswap) +{ + if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE)) + return true; + if (noswap || !total_swap_pages) + return false; + if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON)) + return true; + return false; + +} + +/* + * Always updating the nodemask is not very good - even if we have an empty + * list or the wrong list here, we can start from some node and traverse all + * nodes based on the zonelist. So update the list loosely once per 10 secs. + * + */ +static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg) +{ + int nid; + /* + * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET + * pagein/pageout changes since the last update. + */ + if (!atomic_read(&memcg->numainfo_events)) + return; + if (atomic_inc_return(&memcg->numainfo_updating) > 1) + return; + + /* make a nodemask where this memcg uses memory from */ + memcg->scan_nodes = node_states[N_MEMORY]; + + for_each_node_mask(nid, node_states[N_MEMORY]) { + + if (!test_mem_cgroup_node_reclaimable(memcg, nid, false)) + node_clear(nid, memcg->scan_nodes); + } + + atomic_set(&memcg->numainfo_events, 0); + atomic_set(&memcg->numainfo_updating, 0); +} + +/* + * Selecting a node where we start reclaim from. Because what we need is just + * reducing usage counter, start from anywhere is O,K. Considering + * memory reclaim from current node, there are pros. and cons. + * + * Freeing memory from current node means freeing memory from a node which + * we'll use or we've used. So, it may make LRU bad. And if several threads + * hit limits, it will see a contention on a node. But freeing from remote + * node means more costs for memory reclaim because of memory latency. + * + * Now, we use round-robin. Better algorithm is welcomed. + */ +int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) +{ + int node; + + mem_cgroup_may_update_nodemask(memcg); + node = memcg->last_scanned_node; + + node = next_node_in(node, memcg->scan_nodes); + /* + * mem_cgroup_may_update_nodemask might have seen no reclaimmable pages + * last time it really checked all the LRUs due to rate limiting. + * Fallback to the current node in that case for simplicity. + */ + if (unlikely(node == MAX_NUMNODES)) + node = numa_node_id(); + + memcg->last_scanned_node = node; + return node; +} +#else +int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) +{ + return 0; +} +#endif + +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, + .priority = 0, + }; + + 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, 1, _RET_IP_); + for_each_mem_cgroup_tree(iter, memcg) + iter->oom_lock = false; + spin_unlock(&memcg_oom_lock); +} + +static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + spin_lock(&memcg_oom_lock); + for_each_mem_cgroup_tree(iter, memcg) + iter->under_oom++; + spin_unlock(&memcg_oom_lock); +} + +static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + /* + * When a new child is created while the hierarchy is under oom, + * mem_cgroup_oom_lock() may not be called. Watch for underflow. + */ + spin_lock(&memcg_oom_lock); + for_each_mem_cgroup_tree(iter, memcg) + if (iter->under_oom > 0) + iter->under_oom--; + spin_unlock(&memcg_oom_lock); +} + +static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); + +struct oom_wait_info { + struct mem_cgroup *memcg; + wait_queue_entry_t wait; +}; + +static int memcg_oom_wake_function(wait_queue_entry_t *wait, + unsigned mode, int sync, void *arg) +{ + struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg; + struct mem_cgroup *oom_wait_memcg; + struct oom_wait_info *oom_wait_info; + + oom_wait_info = container_of(wait, struct oom_wait_info, wait); + oom_wait_memcg = oom_wait_info->memcg; + + if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) && + !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg)) + return 0; + return autoremove_wake_function(wait, mode, sync, arg); +} + +static void memcg_oom_recover(struct mem_cgroup *memcg) +{ + /* + * For the following lockless ->under_oom test, the only required + * guarantee is that it must see the state asserted by an OOM when + * this function is called as a result of userland actions + * triggered by the notification of the OOM. This is trivially + * achieved by invoking mem_cgroup_mark_under_oom() before + * triggering notification. + */ + if (memcg && memcg->under_oom) + __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); +} + +enum oom_status { + OOM_SUCCESS, + OOM_FAILED, + OOM_ASYNC, + OOM_SKIPPED +}; + +static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) +{ + enum oom_status ret; + bool locked; + + if (order > PAGE_ALLOC_COSTLY_ORDER) + return OOM_SKIPPED; + + /* + * We are in the middle of the charge context here, so we + * don't want to block when potentially sitting on a callstack + * that holds all kinds of filesystem and mm locks. + * + * cgroup1 allows disabling the OOM killer and waiting for outside + * handling until the charge can succeed; remember the context and put + * the task to sleep at the end of the page fault when all locks are + * released. + * + * On the other hand, in-kernel OOM killer allows for an async victim + * memory reclaim (oom_reaper) and that means that we are not solely + * relying on the oom victim to make a forward progress and we can + * invoke the oom killer here. + * + * Please note that mem_cgroup_out_of_memory might fail to find a + * victim and then we have to bail out from the charge path. + */ + if (memcg->oom_kill_disable) { + if (!current->in_user_fault) + return OOM_SKIPPED; + css_get(&memcg->css); + current->memcg_in_oom = memcg; + current->memcg_oom_gfp_mask = mask; + current->memcg_oom_order = order; + + return OOM_ASYNC; + } + + mem_cgroup_mark_under_oom(memcg); + + locked = mem_cgroup_oom_trylock(memcg); + + if (locked) + mem_cgroup_oom_notify(memcg); + + mem_cgroup_unmark_under_oom(memcg); + if (mem_cgroup_out_of_memory(memcg, mask, order)) + ret = OOM_SUCCESS; + else + ret = OOM_FAILED; + + if (locked) + mem_cgroup_oom_unlock(memcg); + + return ret; +} + +/** + * mem_cgroup_oom_synchronize - complete memcg OOM handling + * @handle: actually kill/wait or just clean up the OOM state + * + * This has to be called at the end of a page fault if the memcg OOM + * handler was enabled. + * + * Memcg supports userspace OOM handling where failed allocations must + * sleep on a waitqueue until the userspace task resolves the + * situation. Sleeping directly in the charge context with all kinds + * of locks held is not a good idea, instead we remember an OOM state + * in the task and mem_cgroup_oom_synchronize() has to be called at + * the end of the page fault to complete the OOM handling. + * + * Returns %true if an ongoing memcg OOM situation was detected and + * completed, %false otherwise. + */ +bool mem_cgroup_oom_synchronize(bool handle) +{ + struct mem_cgroup *memcg = current->memcg_in_oom; + struct oom_wait_info owait; + bool locked; + + /* OOM is global, do not handle */ + if (!memcg) + return false; + + if (!handle) + goto cleanup; + + owait.memcg = memcg; + owait.wait.flags = 0; + owait.wait.func = memcg_oom_wake_function; + owait.wait.private = current; + INIT_LIST_HEAD(&owait.wait.entry); + + prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); + mem_cgroup_mark_under_oom(memcg); + + locked = mem_cgroup_oom_trylock(memcg); + + if (locked) + mem_cgroup_oom_notify(memcg); + + if (locked && !memcg->oom_kill_disable) { + mem_cgroup_unmark_under_oom(memcg); + finish_wait(&memcg_oom_waitq, &owait.wait); + mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask, + current->memcg_oom_order); + } else { + schedule(); + mem_cgroup_unmark_under_oom(memcg); + finish_wait(&memcg_oom_waitq, &owait.wait); + } + + if (locked) { + mem_cgroup_oom_unlock(memcg); + /* + * There is no guarantee that an OOM-lock contender + * sees the wakeups triggered by the OOM kill + * uncharges. Wake any sleepers explicitely. + */ + memcg_oom_recover(memcg); + } +cleanup: + current->memcg_in_oom = NULL; + css_put(&memcg->css); + return true; +} + +/** + * mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM + * @victim: task to be killed by the OOM killer + * @oom_domain: memcg in case of memcg OOM, NULL in case of system-wide OOM + * + * Returns a pointer to a memory cgroup, which has to be cleaned up + * by killing all belonging OOM-killable tasks. + * + * Caller has to call mem_cgroup_put() on the returned non-NULL memcg. + */ +struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim, + struct mem_cgroup *oom_domain) +{ + struct mem_cgroup *oom_group = NULL; + struct mem_cgroup *memcg; + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return NULL; + + if (!oom_domain) + oom_domain = root_mem_cgroup; + + rcu_read_lock(); + + memcg = mem_cgroup_from_task(victim); + if (memcg == root_mem_cgroup) + goto out; + + /* + * Traverse the memory cgroup hierarchy from the victim task's + * cgroup up to the OOMing cgroup (or root) to find the + * highest-level memory cgroup with oom.group set. + */ + for (; memcg; memcg = parent_mem_cgroup(memcg)) { + if (memcg->oom_group) + oom_group = memcg; + + if (memcg == oom_domain) + break; + } + + if (oom_group) + css_get(&oom_group->css); +out: + rcu_read_unlock(); + + return oom_group; +} + +void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) +{ + pr_info("Tasks in "); + pr_cont_cgroup_path(memcg->css.cgroup); + pr_cont(" are going to be killed due to memory.oom.group set\n"); +} + +/** + * lock_page_memcg - lock a page->mem_cgroup binding + * @page: the page + * + * This function protects unlocked LRU pages from being moved to + * another cgroup. + * + * It ensures lifetime of the returned memcg. Caller is responsible + * for the lifetime of the page; __unlock_page_memcg() is available + * when @page might get freed inside the locked section. + */ +struct mem_cgroup *lock_page_memcg(struct page *page) +{ + struct mem_cgroup *memcg; + unsigned long flags; + + /* + * The RCU lock is held throughout the transaction. The fast + * path can get away without acquiring the memcg->move_lock + * because page moving starts with an RCU grace period. + * + * The RCU lock also protects the memcg from being freed when + * the page state that is going to change is the only thing + * preventing the page itself from being freed. E.g. writeback + * doesn't hold a page reference and relies on PG_writeback to + * keep off truncation, migration and so forth. + */ + rcu_read_lock(); + + if (mem_cgroup_disabled()) + return NULL; +again: + memcg = page->mem_cgroup; + if (unlikely(!memcg)) + return NULL; + + if (atomic_read(&memcg->moving_account) <= 0) + return memcg; + + spin_lock_irqsave(&memcg->move_lock, flags); + if (memcg != page->mem_cgroup) { + spin_unlock_irqrestore(&memcg->move_lock, flags); + goto again; + } + + /* + * When charge migration first begins, we can have locked and + * unlocked page stat updates happening concurrently. Track + * the task who has the lock for unlock_page_memcg(). + */ + memcg->move_lock_task = current; + memcg->move_lock_flags = flags; + + return memcg; +} +EXPORT_SYMBOL(lock_page_memcg); + +/** + * __unlock_page_memcg - unlock and unpin a memcg + * @memcg: the memcg + * + * Unlock and unpin a memcg returned by lock_page_memcg(). + */ +void __unlock_page_memcg(struct mem_cgroup *memcg) +{ + if (memcg && memcg->move_lock_task == current) { + unsigned long flags = memcg->move_lock_flags; + + memcg->move_lock_task = NULL; + memcg->move_lock_flags = 0; + + spin_unlock_irqrestore(&memcg->move_lock, flags); + } + + rcu_read_unlock(); +} + +/** + * unlock_page_memcg - unlock a page->mem_cgroup binding + * @page: the page + */ +void unlock_page_memcg(struct page *page) +{ + __unlock_page_memcg(page->mem_cgroup); +} +EXPORT_SYMBOL(unlock_page_memcg); + +struct memcg_stock_pcp { + struct mem_cgroup *cached; /* this never be root cgroup */ + unsigned int nr_pages; + struct work_struct work; + unsigned long flags; +#define FLUSHING_CACHED_CHARGE 0 +}; +static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); +static DEFINE_MUTEX(percpu_charge_mutex); + +/** + * consume_stock: Try to consume stocked charge on this cpu. + * @memcg: memcg to consume from. + * @nr_pages: how many pages to charge. + * + * The charges will only happen if @memcg matches the current cpu's memcg + * stock, and at least @nr_pages are available in that stock. Failure to + * service an allocation will refill the stock. + * + * returns true if successful, false otherwise. + */ +static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) +{ + struct memcg_stock_pcp *stock; + unsigned long flags; + bool ret = false; + + if (nr_pages > MEMCG_CHARGE_BATCH) + return ret; + + local_irq_save(flags); + + stock = this_cpu_ptr(&memcg_stock); + if (memcg == stock->cached && stock->nr_pages >= nr_pages) { + stock->nr_pages -= nr_pages; + ret = true; + } + + local_irq_restore(flags); + + return ret; +} + +/* + * Returns stocks cached in percpu and reset cached information. + */ +static void drain_stock(struct memcg_stock_pcp *stock) +{ + struct mem_cgroup *old = stock->cached; + + if (stock->nr_pages) { + page_counter_uncharge(&old->memory, stock->nr_pages); + if (do_memsw_account()) + page_counter_uncharge(&old->memsw, stock->nr_pages); + css_put_many(&old->css, stock->nr_pages); + stock->nr_pages = 0; + } + stock->cached = NULL; +} + +static void drain_local_stock(struct work_struct *dummy) +{ + struct memcg_stock_pcp *stock; + unsigned long flags; + + /* + * The only protection from memory hotplug vs. drain_stock races is + * that we always operate on local CPU stock here with IRQ disabled + */ + local_irq_save(flags); + + stock = this_cpu_ptr(&memcg_stock); + drain_stock(stock); + clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); + + local_irq_restore(flags); +} + +/* + * Cache charges(val) to local per_cpu area. + * This will be consumed by consume_stock() function, later. + */ +static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) +{ + struct memcg_stock_pcp *stock; + unsigned long flags; + + local_irq_save(flags); + + stock = this_cpu_ptr(&memcg_stock); + if (stock->cached != memcg) { /* reset if necessary */ + drain_stock(stock); + stock->cached = memcg; + } + stock->nr_pages += nr_pages; + + if (stock->nr_pages > MEMCG_CHARGE_BATCH) + drain_stock(stock); + + local_irq_restore(flags); +} + +/* + * Drains all per-CPU charge caches for given root_memcg resp. subtree + * of the hierarchy under it. + */ +static void drain_all_stock(struct mem_cgroup *root_memcg) +{ + int cpu, curcpu; + + /* If someone's already draining, avoid adding running more workers. */ + if (!mutex_trylock(&percpu_charge_mutex)) + return; + /* + * Notify other cpus that system-wide "drain" is running + * We do not care about races with the cpu hotplug because cpu down + * as well as workers from this path always operate on the local + * per-cpu data. CPU up doesn't touch memcg_stock at all. + */ + curcpu = get_cpu(); + for_each_online_cpu(cpu) { + struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); + struct mem_cgroup *memcg; + + memcg = stock->cached; + if (!memcg || !stock->nr_pages || !css_tryget(&memcg->css)) + continue; + if (!mem_cgroup_is_descendant(memcg, root_memcg)) { + css_put(&memcg->css); + continue; + } + if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) { + if (cpu == curcpu) + drain_local_stock(&stock->work); + else + schedule_work_on(cpu, &stock->work); + } + css_put(&memcg->css); + } + put_cpu(); + mutex_unlock(&percpu_charge_mutex); +} + +static int memcg_hotplug_cpu_dead(unsigned int cpu) +{ + struct memcg_stock_pcp *stock; + struct mem_cgroup *memcg; + + stock = &per_cpu(memcg_stock, cpu); + drain_stock(stock); + + for_each_mem_cgroup(memcg) { + int i; + + for (i = 0; i < MEMCG_NR_STAT; i++) { + int nid; + long x; + + x = this_cpu_xchg(memcg->stat_cpu->count[i], 0); + if (x) + atomic_long_add(x, &memcg->stat[i]); + + if (i >= NR_VM_NODE_STAT_ITEMS) + continue; + + for_each_node(nid) { + struct mem_cgroup_per_node *pn; + + pn = mem_cgroup_nodeinfo(memcg, nid); + x = this_cpu_xchg(pn->lruvec_stat_cpu->count[i], 0); + if (x) + atomic_long_add(x, &pn->lruvec_stat[i]); + } + } + + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) { + long x; + + x = this_cpu_xchg(memcg->stat_cpu->events[i], 0); + if (x) + atomic_long_add(x, &memcg->events[i]); + } + } + + return 0; +} + +static void reclaim_high(struct mem_cgroup *memcg, + unsigned int nr_pages, + gfp_t gfp_mask) +{ + do { + if (page_counter_read(&memcg->memory) <= memcg->high) + continue; + memcg_memory_event(memcg, MEMCG_HIGH); + try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); + } while ((memcg = parent_mem_cgroup(memcg))); +} + +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); +} + +/* + * 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 int nr_pages = current->memcg_nr_pages_over_high; + struct mem_cgroup *memcg; + + if (likely(!nr_pages)) + return; + + memcg = get_mem_cgroup_from_mm(current->mm); + reclaim_high(memcg, nr_pages, GFP_KERNEL); + css_put(&memcg->css); + current->memcg_nr_pages_over_high = 0; +} + +static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, + unsigned int nr_pages) +{ + unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); + int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; + struct mem_cgroup *mem_over_limit; + struct page_counter *counter; + unsigned long nr_reclaimed; + bool may_swap = true; + bool drained = false; + bool oomed = false; + enum oom_status oom_status; + + if (mem_cgroup_is_root(memcg)) + return 0; +retry: + if (consume_stock(memcg, nr_pages)) + return 0; + + if (!do_memsw_account() || + page_counter_try_charge(&memcg->memsw, batch, &counter)) { + if (page_counter_try_charge(&memcg->memory, batch, &counter)) + goto done_restock; + if (do_memsw_account()) + page_counter_uncharge(&memcg->memsw, batch); + mem_over_limit = mem_cgroup_from_counter(counter, memory); + } else { + mem_over_limit = mem_cgroup_from_counter(counter, memsw); + may_swap = false; + } + + if (batch > nr_pages) { + batch = nr_pages; + goto retry; + } + + /* + * Memcg doesn't have a dedicated reserve for atomic + * allocations. But like the global atomic pool, we need to + * put the burden of reclaim on regular allocation requests + * and let these go through as privileged allocations. + */ + if (gfp_mask & __GFP_ATOMIC) + goto force; + + /* + * Unlike in global OOM situations, memcg is not in a physical + * memory shortage. Allow dying and OOM-killed tasks to + * bypass the last charges so that they can exit quickly and + * free their memory. + */ + if (unlikely(should_force_charge())) + goto force; + + /* + * Prevent unbounded recursion when reclaim operations need to + * allocate memory. This might exceed the limits temporarily, + * but we prefer facilitating memory reclaim and getting back + * under the limit over triggering OOM kills in these cases. + */ + if (unlikely(current->flags & PF_MEMALLOC)) + goto force; + + if (unlikely(task_in_memcg_oom(current))) + goto nomem; + + if (!gfpflags_allow_blocking(gfp_mask)) + goto nomem; + + memcg_memory_event(mem_over_limit, MEMCG_MAX); + + nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, + gfp_mask, may_swap); + + if (mem_cgroup_margin(mem_over_limit) >= nr_pages) + goto retry; + + if (!drained) { + drain_all_stock(mem_over_limit); + drained = true; + goto retry; + } + + if (gfp_mask & __GFP_NORETRY) + goto nomem; + /* + * Even though the limit is exceeded at this point, reclaim + * may have been able to free some pages. Retry the charge + * before killing the task. + * + * Only for regular pages, though: huge pages are rather + * unlikely to succeed so close to the limit, and we fall back + * to regular pages anyway in case of failure. + */ + if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER)) + goto retry; + /* + * At task move, charge accounts can be doubly counted. So, it's + * better to wait until the end of task_move if something is going on. + */ + if (mem_cgroup_wait_acct_move(mem_over_limit)) + goto retry; + + if (nr_retries--) + goto retry; + + if (gfp_mask & __GFP_RETRY_MAYFAIL && oomed) + goto nomem; + + if (gfp_mask & __GFP_NOFAIL) + goto force; + + if (fatal_signal_pending(current)) + goto force; + + memcg_memory_event(mem_over_limit, MEMCG_OOM); + + /* + * keep retrying as long as the memcg oom killer is able to make + * a forward progress or bypass the charge if the oom killer + * couldn't make any progress. + */ + oom_status = mem_cgroup_oom(mem_over_limit, gfp_mask, + get_order(nr_pages * PAGE_SIZE)); + switch (oom_status) { + case OOM_SUCCESS: + nr_retries = MEM_CGROUP_RECLAIM_RETRIES; + oomed = true; + goto retry; + case OOM_FAILED: + goto force; + default: + goto nomem; + } +nomem: + if (!(gfp_mask & __GFP_NOFAIL)) + return -ENOMEM; +force: + /* + * The allocation either can't fail or will lead to more memory + * being freed very soon. Allow memory usage go over the limit + * temporarily by force charging it. + */ + page_counter_charge(&memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_charge(&memcg->memsw, nr_pages); + css_get_many(&memcg->css, nr_pages); + + return 0; + +done_restock: + css_get_many(&memcg->css, batch); + if (batch > nr_pages) + refill_stock(memcg, batch - nr_pages); + + /* + * If the hierarchy is above the normal consumption range, schedule + * reclaim on returning to userland. We can perform reclaim here + * if __GFP_RECLAIM but let's always punt for simplicity and so that + * GFP_KERNEL can consistently be used during reclaim. @memcg is + * not recorded as it most likely matches current's and won't + * change in the meantime. As high limit is checked again before + * reclaim, the cost of mismatch is negligible. + */ + do { + if (page_counter_read(&memcg->memory) > memcg->high) { + /* Don't bother a random interrupted task */ + if (in_interrupt()) { + schedule_work(&memcg->high_work); + break; + } + current->memcg_nr_pages_over_high += batch; + set_notify_resume(current); + break; + } + } while ((memcg = parent_mem_cgroup(memcg))); + + return 0; +} + +static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) +{ + if (mem_cgroup_is_root(memcg)) + return; + + page_counter_uncharge(&memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_uncharge(&memcg->memsw, nr_pages); + + css_put_many(&memcg->css, nr_pages); +} + +static void lock_page_lru(struct page *page, int *isolated) +{ + struct zone *zone = page_zone(page); + + spin_lock_irq(zone_lru_lock(zone)); + if (PageLRU(page)) { + struct lruvec *lruvec; + + lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); + ClearPageLRU(page); + del_page_from_lru_list(page, lruvec, page_lru(page)); + *isolated = 1; + } else + *isolated = 0; +} + +static void unlock_page_lru(struct page *page, int isolated) +{ + struct zone *zone = page_zone(page); + + if (isolated) { + struct lruvec *lruvec; + + lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat); + VM_BUG_ON_PAGE(PageLRU(page), page); + SetPageLRU(page); + add_page_to_lru_list(page, lruvec, page_lru(page)); + } + spin_unlock_irq(zone_lru_lock(zone)); +} + +static void commit_charge(struct page *page, struct mem_cgroup *memcg, + bool lrucare) +{ + int isolated; + + VM_BUG_ON_PAGE(page->mem_cgroup, page); + + /* + * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page + * may already be on some other mem_cgroup's LRU. Take care of it. + */ + if (lrucare) + lock_page_lru(page, &isolated); + + /* + * Nobody should be changing or seriously looking at + * page->mem_cgroup at this point: + * + * - the page is uncharged + * + * - the page is off-LRU + * + * - an anonymous fault has exclusive page access, except for + * a locked page table + * + * - a page cache insertion, a swapin fault, or a migration + * have the page locked + */ + page->mem_cgroup = memcg; + + if (lrucare) + unlock_page_lru(page, isolated); +} + +#ifdef CONFIG_MEMCG_KMEM +static int memcg_alloc_cache_id(void) +{ + int id, size; + int err; + + id = ida_simple_get(&memcg_cache_ida, + 0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL); + if (id < 0) + return id; + + if (id < memcg_nr_cache_ids) + return id; + + /* + * There's no space for the new id in memcg_caches arrays, + * so we have to grow them. + */ + down_write(&memcg_cache_ids_sem); + + size = 2 * (id + 1); + if (size < MEMCG_CACHES_MIN_SIZE) + size = MEMCG_CACHES_MIN_SIZE; + else if (size > MEMCG_CACHES_MAX_SIZE) + size = MEMCG_CACHES_MAX_SIZE; + + err = memcg_update_all_caches(size); + if (!err) + err = memcg_update_all_list_lrus(size); + if (!err) + memcg_nr_cache_ids = size; + + up_write(&memcg_cache_ids_sem); + + if (err) { + ida_simple_remove(&memcg_cache_ida, id); + return err; + } + return id; +} + +static void memcg_free_cache_id(int id) +{ + ida_simple_remove(&memcg_cache_ida, id); +} + +struct memcg_kmem_cache_create_work { + struct mem_cgroup *memcg; + struct kmem_cache *cachep; + struct work_struct work; +}; + +static void memcg_kmem_cache_create_func(struct work_struct *w) +{ + struct memcg_kmem_cache_create_work *cw = + container_of(w, struct memcg_kmem_cache_create_work, work); + struct mem_cgroup *memcg = cw->memcg; + struct kmem_cache *cachep = cw->cachep; + + memcg_create_kmem_cache(memcg, cachep); + + css_put(&memcg->css); + kfree(cw); +} + +/* + * Enqueue the creation of a per-memcg kmem_cache. + */ +static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, + struct kmem_cache *cachep) +{ + struct memcg_kmem_cache_create_work *cw; + + cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN); + if (!cw) + return; + + css_get(&memcg->css); + + cw->memcg = memcg; + cw->cachep = cachep; + INIT_WORK(&cw->work, memcg_kmem_cache_create_func); + + queue_work(memcg_kmem_cache_wq, &cw->work); +} + +static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, + struct kmem_cache *cachep) +{ + /* + * We need to stop accounting when we kmalloc, because if the + * corresponding kmalloc cache is not yet created, the first allocation + * in __memcg_schedule_kmem_cache_create will recurse. + * + * However, it is better to enclose the whole function. Depending on + * the debugging options enabled, INIT_WORK(), for instance, can + * trigger an allocation. This too, will make us recurse. Because at + * this point we can't allow ourselves back into memcg_kmem_get_cache, + * the safest choice is to do it like this, wrapping the whole function. + */ + current->memcg_kmem_skip_account = 1; + __memcg_schedule_kmem_cache_create(memcg, cachep); + current->memcg_kmem_skip_account = 0; +} + +static inline bool memcg_kmem_bypass(void) +{ + if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD)) + return true; + return false; +} + +/** + * memcg_kmem_get_cache: select the correct per-memcg cache for allocation + * @cachep: the original global kmem cache + * + * Return the kmem_cache we're supposed to use for a slab allocation. + * We try to use the current memcg's version of the cache. + * + * If the cache does not exist yet, if we are the first user of it, we + * create it asynchronously in a workqueue and let the current allocation + * go through with the original cache. + * + * This function takes a reference to the cache it returns to assure it + * won't get destroyed while we are working with it. Once the caller is + * done with it, memcg_kmem_put_cache() must be called to release the + * reference. + */ +struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep) +{ + struct mem_cgroup *memcg; + struct kmem_cache *memcg_cachep; + int kmemcg_id; + + VM_BUG_ON(!is_root_cache(cachep)); + + if (memcg_kmem_bypass()) + return cachep; + + if (current->memcg_kmem_skip_account) + return cachep; + + memcg = get_mem_cgroup_from_current(); + kmemcg_id = READ_ONCE(memcg->kmemcg_id); + if (kmemcg_id < 0) + goto out; + + memcg_cachep = cache_from_memcg_idx(cachep, kmemcg_id); + if (likely(memcg_cachep)) + return memcg_cachep; + + /* + * If we are in a safe context (can wait, and not in interrupt + * context), we could be be predictable and return right away. + * This would guarantee that the allocation being performed + * already belongs in the new cache. + * + * However, there are some clashes that can arrive from locking. + * For instance, because we acquire the slab_mutex while doing + * memcg_create_kmem_cache, this means no further allocation + * could happen with the slab_mutex held. So it's better to + * defer everything. + */ + memcg_schedule_kmem_cache_create(memcg, cachep); +out: + css_put(&memcg->css); + return cachep; +} + +/** + * memcg_kmem_put_cache: drop reference taken by memcg_kmem_get_cache + * @cachep: the cache returned by memcg_kmem_get_cache + */ +void memcg_kmem_put_cache(struct kmem_cache *cachep) +{ + if (!is_root_cache(cachep)) + css_put(&cachep->memcg_params.memcg->css); +} + +/** + * memcg_kmem_charge_memcg: charge a kmem page + * @page: page to charge + * @gfp: reclaim mode + * @order: allocation order + * @memcg: memory cgroup to charge + * + * Returns 0 on success, an error code on failure. + */ +int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order, + struct mem_cgroup *memcg) +{ + unsigned int nr_pages = 1 << order; + struct page_counter *counter; + int ret; + + ret = try_charge(memcg, gfp, nr_pages); + if (ret) + return ret; + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && + !page_counter_try_charge(&memcg->kmem, nr_pages, &counter)) { + + /* + * Enforce __GFP_NOFAIL allocation because callers are not + * prepared to see failures and likely do not have any failure + * handling code. + */ + if (gfp & __GFP_NOFAIL) { + page_counter_charge(&memcg->kmem, nr_pages); + return 0; + } + cancel_charge(memcg, nr_pages); + return -ENOMEM; + } + + page->mem_cgroup = memcg; + + return 0; +} + +/** + * memcg_kmem_charge: 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(struct page *page, gfp_t gfp, int order) +{ + struct mem_cgroup *memcg; + int ret = 0; + + if (mem_cgroup_disabled() || memcg_kmem_bypass()) + return 0; + + memcg = get_mem_cgroup_from_current(); + if (!mem_cgroup_is_root(memcg)) { + ret = memcg_kmem_charge_memcg(page, gfp, order, memcg); + if (!ret) + __SetPageKmemcg(page); + } + css_put(&memcg->css); + return ret; +} +/** + * memcg_kmem_uncharge: uncharge a kmem page + * @page: page to uncharge + * @order: allocation order + */ +void memcg_kmem_uncharge(struct page *page, int order) +{ + struct mem_cgroup *memcg = page->mem_cgroup; + unsigned int nr_pages = 1 << order; + + if (!memcg) + return; + + VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page); + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) + page_counter_uncharge(&memcg->kmem, nr_pages); + + page_counter_uncharge(&memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_uncharge(&memcg->memsw, nr_pages); + + page->mem_cgroup = NULL; + + /* slab pages do not have PageKmemcg flag set */ + if (PageKmemcg(page)) + __ClearPageKmemcg(page); + + css_put_many(&memcg->css, nr_pages); +} +#endif /* CONFIG_MEMCG_KMEM */ + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + +/* + * Because tail pages are not marked as "used", set it. We're under + * zone_lru_lock and migration entries setup in all page mappings. + */ +void mem_cgroup_split_huge_fixup(struct page *head) +{ + int i; + + if (mem_cgroup_disabled()) + return; + + for (i = 1; i < HPAGE_PMD_NR; i++) + head[i].mem_cgroup = head->mem_cgroup; + + __mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PMD_NR); +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#ifdef CONFIG_MEMCG_SWAP +/** + * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. + * @entry: swap entry to be moved + * @from: mem_cgroup which the entry is moved from + * @to: mem_cgroup which the entry is moved to + * + * It succeeds only when the swap_cgroup's record for this entry is the same + * as the mem_cgroup's id of @from. + * + * Returns 0 on success, -EINVAL on failure. + * + * The caller must have charged to @to, IOW, called page_counter_charge() about + * both res and memsw, and called css_get(). + */ +static int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + unsigned short old_id, new_id; + + old_id = mem_cgroup_id(from); + new_id = mem_cgroup_id(to); + + if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { + mod_memcg_state(from, MEMCG_SWAP, -1); + mod_memcg_state(to, MEMCG_SWAP, 1); + return 0; + } + return -EINVAL; +} +#else +static inline int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + return -EINVAL; +} +#endif + +static DEFINE_MUTEX(memcg_max_mutex); + +static int mem_cgroup_resize_max(struct mem_cgroup *memcg, + unsigned long max, bool memsw) +{ + bool enlarge = false; + bool drained = false; + int ret; + bool limits_invariant; + struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory; + + do { + if (signal_pending(current)) { + ret = -EINTR; + break; + } + + mutex_lock(&memcg_max_mutex); + /* + * Make sure that the new limit (memsw or memory limit) doesn't + * break our basic invariant rule memory.max <= memsw.max. + */ + limits_invariant = memsw ? max >= memcg->memory.max : + max <= memcg->memsw.max; + if (!limits_invariant) { + mutex_unlock(&memcg_max_mutex); + ret = -EINVAL; + break; + } + if (max > counter->max) + enlarge = true; + ret = page_counter_set_max(counter, max); + mutex_unlock(&memcg_max_mutex); + + if (!ret) + break; + + if (!drained) { + drain_all_stock(memcg); + drained = true; + continue; + } + + if (!try_to_free_mem_cgroup_pages(memcg, 1, + GFP_KERNEL, !memsw)) { + ret = -EBUSY; + break; + } + } while (true); + + if (!ret && enlarge) + memcg_oom_recover(memcg); + + return ret; +} + +unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, + gfp_t gfp_mask, + unsigned long *total_scanned) +{ + unsigned long nr_reclaimed = 0; + struct mem_cgroup_per_node *mz, *next_mz = NULL; + unsigned long reclaimed; + int loop = 0; + struct mem_cgroup_tree_per_node *mctz; + unsigned long excess; + unsigned long nr_scanned; + + if (order > 0) + return 0; + + mctz = soft_limit_tree_node(pgdat->node_id); + + /* + * Do not even bother to check the largest node if the root + * is empty. Do it lockless to prevent lock bouncing. Races + * are acceptable as soft limit is best effort anyway. + */ + if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root)) + return 0; + + /* + * This loop can run a while, specially if mem_cgroup's continuously + * keep exceeding their soft limit and putting the system under + * pressure + */ + do { + if (next_mz) + mz = next_mz; + else + mz = mem_cgroup_largest_soft_limit_node(mctz); + if (!mz) + break; + + nr_scanned = 0; + reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat, + gfp_mask, &nr_scanned); + nr_reclaimed += reclaimed; + *total_scanned += nr_scanned; + spin_lock_irq(&mctz->lock); + __mem_cgroup_remove_exceeded(mz, mctz); + + /* + * If we failed to reclaim anything from this memory cgroup + * it is time to move on to the next cgroup + */ + next_mz = NULL; + if (!reclaimed) + next_mz = __mem_cgroup_largest_soft_limit_node(mctz); + + excess = soft_limit_excess(mz->memcg); + /* + * One school of thought says that we should not add + * back the node to the tree if reclaim returns 0. + * But our reclaim could return 0, simply because due + * to priority we are exposing a smaller subset of + * memory to reclaim from. Consider this as a longer + * term TODO. + */ + /* If excess == 0, no tree ops */ + __mem_cgroup_insert_exceeded(mz, mctz, excess); + spin_unlock_irq(&mctz->lock); + css_put(&mz->memcg->css); + loop++; + /* + * Could not reclaim anything and there are no more + * mem cgroups to try or we seem to be looping without + * reclaiming anything. + */ + if (!nr_reclaimed && + (next_mz == NULL || + loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) + break; + } while (!nr_reclaimed); + if (next_mz) + css_put(&next_mz->memcg->css); + return nr_reclaimed; +} + +/* + * Test whether @memcg has children, dead or alive. Note that this + * function doesn't care whether @memcg has use_hierarchy enabled and + * returns %true if there are child csses according to the cgroup + * hierarchy. Testing use_hierarchy is the caller's responsiblity. + */ +static inline bool memcg_has_children(struct mem_cgroup *memcg) +{ + bool ret; + + rcu_read_lock(); + ret = css_next_child(NULL, &memcg->css); + rcu_read_unlock(); + return ret; +} + +/* + * Reclaims as many pages from the given memcg as possible. + * + * Caller is responsible for holding css reference for memcg. + */ +static int mem_cgroup_force_empty(struct mem_cgroup *memcg) +{ + int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; + + /* we call try-to-free pages for make this cgroup empty */ + lru_add_drain_all(); + + drain_all_stock(memcg); + + /* try to free all pages in this cgroup */ + while (nr_retries && page_counter_read(&memcg->memory)) { + int progress; + + if (signal_pending(current)) + return -EINTR; + + progress = try_to_free_mem_cgroup_pages(memcg, 1, + GFP_KERNEL, true); + if (!progress) { + nr_retries--; + /* maybe some writeback is necessary */ + congestion_wait(BLK_RW_ASYNC, HZ/10); + } + + } + + return 0; +} + +static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, + loff_t off) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + + if (mem_cgroup_is_root(memcg)) + return -EINVAL; + return mem_cgroup_force_empty(memcg) ?: nbytes; +} + +static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return mem_cgroup_from_css(css)->use_hierarchy; +} + +static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + int retval = 0; + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup *parent_memcg = mem_cgroup_from_css(memcg->css.parent); + + if (memcg->use_hierarchy == val) + return 0; + + /* + * If parent's use_hierarchy is set, we can't make any modifications + * in the child subtrees. If it is unset, then the change can + * occur, provided the current cgroup has no children. + * + * For the root cgroup, parent_mem is NULL, we allow value to be + * set if there are no children. + */ + if ((!parent_memcg || !parent_memcg->use_hierarchy) && + (val == 1 || val == 0)) { + if (!memcg_has_children(memcg)) + memcg->use_hierarchy = val; + else + retval = -EBUSY; + } else + retval = -EINVAL; + + return retval; +} + +struct accumulated_stats { + unsigned long stat[MEMCG_NR_STAT]; + unsigned long events[NR_VM_EVENT_ITEMS]; + unsigned long lru_pages[NR_LRU_LISTS]; + const unsigned int *stats_array; + const unsigned int *events_array; + int stats_size; + int events_size; +}; + +static void accumulate_memcg_tree(struct mem_cgroup *memcg, + struct accumulated_stats *acc) +{ + struct mem_cgroup *mi; + int i; + + for_each_mem_cgroup_tree(mi, memcg) { + for (i = 0; i < acc->stats_size; i++) + acc->stat[i] += memcg_page_state(mi, + acc->stats_array ? acc->stats_array[i] : i); + + for (i = 0; i < acc->events_size; i++) + acc->events[i] += memcg_sum_events(mi, + acc->events_array ? acc->events_array[i] : i); + + for (i = 0; i < NR_LRU_LISTS; i++) + acc->lru_pages[i] += + mem_cgroup_nr_lru_pages(mi, BIT(i)); + } +} + +static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) +{ + unsigned long val = 0; + + if (mem_cgroup_is_root(memcg)) { + struct mem_cgroup *iter; + + for_each_mem_cgroup_tree(iter, memcg) { + val += memcg_page_state(iter, MEMCG_CACHE); + val += memcg_page_state(iter, MEMCG_RSS); + if (swap) + val += memcg_page_state(iter, 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) +{ + int memcg_id; + + if (cgroup_memory_nokmem) + return 0; + + BUG_ON(memcg->kmemcg_id >= 0); + BUG_ON(memcg->kmem_state); + + memcg_id = memcg_alloc_cache_id(); + if (memcg_id < 0) + return memcg_id; + + static_branch_inc(&memcg_kmem_enabled_key); + /* + * A memory cgroup is considered kmem-online as soon as it gets + * kmemcg_id. Setting the id after enabling static branching will + * guarantee no one starts accounting before all call sites are + * patched. + */ + memcg->kmemcg_id = memcg_id; + memcg->kmem_state = KMEM_ONLINE; + INIT_LIST_HEAD(&memcg->kmem_caches); + + return 0; +} + +static void memcg_offline_kmem(struct mem_cgroup *memcg) +{ + struct cgroup_subsys_state *css; + struct mem_cgroup *parent, *child; + int kmemcg_id; + + if (memcg->kmem_state != KMEM_ONLINE) + return; + /* + * Clear the online state before clearing memcg_caches array + * entries. The slab_mutex in memcg_deactivate_kmem_caches() + * guarantees that no cache will be created for this cgroup + * after we are done (see memcg_create_kmem_cache()). + */ + memcg->kmem_state = KMEM_ALLOCATED; + + memcg_deactivate_kmem_caches(memcg); + + kmemcg_id = memcg->kmemcg_id; + BUG_ON(kmemcg_id < 0); + + parent = parent_mem_cgroup(memcg); + if (!parent) + parent = root_mem_cgroup; + + /* + * Change kmemcg_id of this cgroup and all its descendants to the + * parent's id, and then move all entries from this cgroup's list_lrus + * to ones of the parent. After we have finished, all list_lrus + * corresponding to this cgroup are guaranteed to remain empty. The + * ordering is imposed by list_lru_node->lock taken by + * memcg_drain_all_list_lrus(). + */ + rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */ + css_for_each_descendant_pre(css, &memcg->css) { + child = mem_cgroup_from_css(css); + BUG_ON(child->kmemcg_id != kmemcg_id); + child->kmemcg_id = parent->kmemcg_id; + if (!memcg->use_hierarchy) + break; + } + rcu_read_unlock(); + + memcg_drain_all_list_lrus(kmemcg_id, parent); + + memcg_free_cache_id(kmemcg_id); +} + +static void memcg_free_kmem(struct mem_cgroup *memcg) +{ + /* css_alloc() failed, offlining didn't happen */ + if (unlikely(memcg->kmem_state == KMEM_ONLINE)) + memcg_offline_kmem(memcg); + + if (memcg->kmem_state == KMEM_ALLOCATED) { + memcg_destroy_kmem_caches(memcg); + static_branch_dec(&memcg_kmem_enabled_key); + WARN_ON(page_counter_read(&memcg->kmem)); + } +} +#else +static int memcg_online_kmem(struct mem_cgroup *memcg) +{ + return 0; +} +static void memcg_offline_kmem(struct mem_cgroup *memcg) +{ +} +static void memcg_free_kmem(struct mem_cgroup *memcg) +{ +} +#endif /* CONFIG_MEMCG_KMEM */ + +static int memcg_update_kmem_max(struct mem_cgroup *memcg, + unsigned long max) +{ + int ret; + + mutex_lock(&memcg_max_mutex); + ret = page_counter_set_max(&memcg->kmem, max); + mutex_unlock(&memcg_max_mutex); + return ret; +} + +static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max) +{ + int ret; + + mutex_lock(&memcg_max_mutex); + + ret = page_counter_set_max(&memcg->tcpmem, max); + if (ret) + goto out; + + if (!memcg->tcpmem_active) { + /* + * The active flag needs to be written after the static_key + * update. This is what guarantees that the socket activation + * function is the last one to run. See mem_cgroup_sk_alloc() + * for details, and note that we don't mark any socket as + * belonging to this memcg until that flag is up. + * + * We need to do this, because static_keys will span multiple + * sites, but we can't control their order. If we mark a socket + * as accounted, but the accounting functions are not patched in + * yet, we'll lose accounting. + * + * We never race with the readers in mem_cgroup_sk_alloc(), + * because when this value change, the code to process it is not + * patched in yet. + */ + static_branch_inc(&memcg_sockets_enabled_key); + memcg->tcpmem_active = true; + } +out: + mutex_unlock(&memcg_max_mutex); + return ret; +} + +/* + * The user of this function is... + * RES_LIMIT. + */ +static ssize_t mem_cgroup_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + unsigned long nr_pages; + int ret; + + buf = strstrip(buf); + ret = page_counter_memparse(buf, "-1", &nr_pages); + if (ret) + return ret; + + switch (MEMFILE_ATTR(of_cft(of)->private)) { + case RES_LIMIT: + if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */ + ret = -EINVAL; + break; + } + switch (MEMFILE_TYPE(of_cft(of)->private)) { + case _MEM: + ret = mem_cgroup_resize_max(memcg, nr_pages, false); + break; + case _MEMSWAP: + ret = mem_cgroup_resize_max(memcg, nr_pages, true); + break; + case _KMEM: + ret = memcg_update_kmem_max(memcg, nr_pages); + break; + case _TCP: + ret = memcg_update_tcp_max(memcg, nr_pages); + break; + } + break; + case RES_SOFT_LIMIT: + memcg->soft_limit = nr_pages; + ret = 0; + break; + } + return ret ?: nbytes; +} + +static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf, + size_t nbytes, loff_t off) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + struct page_counter *counter; + + switch (MEMFILE_TYPE(of_cft(of)->private)) { + case _MEM: + counter = &memcg->memory; + break; + case _MEMSWAP: + counter = &memcg->memsw; + break; + case _KMEM: + counter = &memcg->kmem; + break; + case _TCP: + counter = &memcg->tcpmem; + break; + default: + BUG(); + } + + switch (MEMFILE_ATTR(of_cft(of)->private)) { + case RES_MAX_USAGE: + page_counter_reset_watermark(counter); + break; + case RES_FAILCNT: + counter->failcnt = 0; + break; + default: + BUG(); + } + + return nbytes; +} + +static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return mem_cgroup_from_css(css)->move_charge_at_immigrate; +} + +#ifdef CONFIG_MMU +static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + if (val & ~MOVE_MASK) + return -EINVAL; + + /* + * No kind of locking is needed in here, because ->can_attach() will + * check this value once in the beginning of the process, and then carry + * on with stale data. This means that changes to this value will only + * affect task migrations starting after the change. + */ + memcg->move_charge_at_immigrate = val; + return 0; +} +#else +static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + return -ENOSYS; +} +#endif + +#ifdef CONFIG_NUMA +static int memcg_numa_stat_show(struct seq_file *m, void *v) +{ + struct numa_stat { + const char *name; + unsigned int lru_mask; + }; + + static const struct numa_stat stats[] = { + { "total", LRU_ALL }, + { "file", LRU_ALL_FILE }, + { "anon", LRU_ALL_ANON }, + { "unevictable", BIT(LRU_UNEVICTABLE) }, + }; + const struct numa_stat *stat; + int nid; + unsigned long nr; + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + + for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { + nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask); + seq_printf(m, "%s=%lu", stat->name, nr); + for_each_node_state(nid, N_MEMORY) { + nr = mem_cgroup_node_nr_lru_pages(memcg, nid, + stat->lru_mask); + seq_printf(m, " N%d=%lu", nid, nr); + } + seq_putc(m, '\n'); + } + + for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { + struct mem_cgroup *iter; + + nr = 0; + for_each_mem_cgroup_tree(iter, memcg) + nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask); + seq_printf(m, "hierarchical_%s=%lu", stat->name, nr); + for_each_node_state(nid, N_MEMORY) { + nr = 0; + for_each_mem_cgroup_tree(iter, memcg) + nr += mem_cgroup_node_nr_lru_pages( + iter, nid, stat->lru_mask); + seq_printf(m, " N%d=%lu", nid, nr); + } + seq_putc(m, '\n'); + } + + return 0; +} +#endif /* CONFIG_NUMA */ + +/* Universal VM events cgroup1 shows, original sort order */ +static const unsigned int memcg1_events[] = { + PGPGIN, + PGPGOUT, + PGFAULT, + PGMAJFAULT, +}; + +static const char *const memcg1_event_names[] = { + "pgpgin", + "pgpgout", + "pgfault", + "pgmajfault", +}; + +static int memcg_stat_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long memory, memsw; + struct mem_cgroup *mi; + unsigned int i; + struct accumulated_stats acc; + + BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats)); + BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS); + + for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { + if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) + continue; + seq_printf(m, "%s %lu\n", memcg1_stat_names[i], + memcg_page_state(memcg, memcg1_stats[i]) * + PAGE_SIZE); + } + + for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) + seq_printf(m, "%s %lu\n", memcg1_event_names[i], + memcg_sum_events(memcg, memcg1_events[i])); + + for (i = 0; i < NR_LRU_LISTS; i++) + seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i], + mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE); + + /* Hierarchical information */ + memory = memsw = PAGE_COUNTER_MAX; + for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) { + memory = min(memory, mi->memory.max); + memsw = min(memsw, 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); + + memset(&acc, 0, sizeof(acc)); + acc.stats_size = ARRAY_SIZE(memcg1_stats); + acc.stats_array = memcg1_stats; + acc.events_size = ARRAY_SIZE(memcg1_events); + acc.events_array = memcg1_events; + accumulate_memcg_tree(memcg, &acc); + + for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { + if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account()) + continue; + seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i], + (u64)acc.stat[i] * PAGE_SIZE); + } + + for (i = 0; i < ARRAY_SIZE(memcg1_events); i++) + seq_printf(m, "total_%s %llu\n", memcg1_event_names[i], + (u64)acc.events[i]); + + for (i = 0; i < NR_LRU_LISTS; i++) + seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i], + (u64)acc.lru_pages[i] * PAGE_SIZE); + +#ifdef CONFIG_DEBUG_VM + { + pg_data_t *pgdat; + struct mem_cgroup_per_node *mz; + struct zone_reclaim_stat *rstat; + unsigned long recent_rotated[2] = {0, 0}; + unsigned long recent_scanned[2] = {0, 0}; + + for_each_online_pgdat(pgdat) { + mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id); + rstat = &mz->lruvec.reclaim_stat; + + recent_rotated[0] += rstat->recent_rotated[0]; + recent_rotated[1] += rstat->recent_rotated[1]; + recent_scanned[0] += rstat->recent_scanned[0]; + recent_scanned[1] += rstat->recent_scanned[1]; + } + seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]); + seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]); + seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]); + seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]); + } +#endif + + return 0; +} + +static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + return mem_cgroup_swappiness(memcg); +} + +static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + if (val > 100) + return -EINVAL; + + if (css->parent) + memcg->swappiness = val; + else + vm_swappiness = val; + + return 0; +} + +static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) +{ + struct mem_cgroup_threshold_ary *t; + unsigned long usage; + int i; + + rcu_read_lock(); + if (!swap) + t = rcu_dereference(memcg->thresholds.primary); + else + t = rcu_dereference(memcg->memsw_thresholds.primary); + + if (!t) + goto unlock; + + usage = mem_cgroup_usage(memcg, swap); + + /* + * current_threshold points to threshold just below or equal to usage. + * If it's not true, a threshold was crossed after last + * call of __mem_cgroup_threshold(). + */ + i = t->current_threshold; + + /* + * Iterate backward over array of thresholds starting from + * current_threshold and check if a threshold is crossed. + * If none of thresholds below usage is crossed, we read + * only one element of the array here. + */ + for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--) + eventfd_signal(t->entries[i].eventfd, 1); + + /* i = current_threshold + 1 */ + i++; + + /* + * Iterate forward over array of thresholds starting from + * current_threshold+1 and check if a threshold is crossed. + * If none of thresholds above usage is crossed, we read + * only one element of the array here. + */ + for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++) + eventfd_signal(t->entries[i].eventfd, 1); + + /* Update current_threshold */ + t->current_threshold = i - 1; +unlock: + rcu_read_unlock(); +} + +static void mem_cgroup_threshold(struct mem_cgroup *memcg) +{ + while (memcg) { + __mem_cgroup_threshold(memcg, false); + if (do_memsw_account()) + __mem_cgroup_threshold(memcg, true); + + memcg = parent_mem_cgroup(memcg); + } +} + +static int compare_thresholds(const void *a, const void *b) +{ + const struct mem_cgroup_threshold *_a = a; + const struct mem_cgroup_threshold *_b = b; + + if (_a->threshold > _b->threshold) + return 1; + + if (_a->threshold < _b->threshold) + return -1; + + return 0; +} + +static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg) +{ + struct mem_cgroup_eventfd_list *ev; + + spin_lock(&memcg_oom_lock); + + list_for_each_entry(ev, &memcg->oom_notify, list) + eventfd_signal(ev->eventfd, 1); + + spin_unlock(&memcg_oom_lock); + return 0; +} + +static void mem_cgroup_oom_notify(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + for_each_mem_cgroup_tree(iter, memcg) + mem_cgroup_oom_notify_cb(iter); +} + +static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, + struct eventfd_ctx *eventfd, const char *args, enum res_type type) +{ + struct mem_cgroup_thresholds *thresholds; + struct mem_cgroup_threshold_ary *new; + unsigned long threshold; + unsigned long usage; + int i, size, ret; + + ret = page_counter_memparse(args, "-1", &threshold); + if (ret) + return ret; + + mutex_lock(&memcg->thresholds_lock); + + if (type == _MEM) { + thresholds = &memcg->thresholds; + usage = mem_cgroup_usage(memcg, false); + } else if (type == _MEMSWAP) { + thresholds = &memcg->memsw_thresholds; + usage = mem_cgroup_usage(memcg, true); + } else + BUG(); + + /* Check if a threshold crossed before adding a new one */ + if (thresholds->primary) + __mem_cgroup_threshold(memcg, type == _MEMSWAP); + + size = thresholds->primary ? thresholds->primary->size + 1 : 1; + + /* Allocate memory for new array of thresholds */ + new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold), + GFP_KERNEL); + if (!new) { + ret = -ENOMEM; + goto unlock; + } + new->size = size; + + /* Copy thresholds (if any) to new array */ + if (thresholds->primary) { + memcpy(new->entries, thresholds->primary->entries, (size - 1) * + sizeof(struct mem_cgroup_threshold)); + } + + /* Add new threshold */ + new->entries[size - 1].eventfd = eventfd; + new->entries[size - 1].threshold = threshold; + + /* Sort thresholds. Registering of new threshold isn't time-critical */ + sort(new->entries, size, sizeof(struct mem_cgroup_threshold), + compare_thresholds, NULL); + + /* Find current threshold */ + new->current_threshold = -1; + for (i = 0; i < size; i++) { + if (new->entries[i].threshold <= usage) { + /* + * new->current_threshold will not be used until + * rcu_assign_pointer(), so it's safe to increment + * it here. + */ + ++new->current_threshold; + } else + break; + } + + /* Free old spare buffer and save old primary buffer as spare */ + kfree(thresholds->spare); + thresholds->spare = thresholds->primary; + + rcu_assign_pointer(thresholds->primary, new); + + /* To be sure that nobody uses thresholds */ + synchronize_rcu(); + +unlock: + mutex_unlock(&memcg->thresholds_lock); + + return ret; +} + +static 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_css(seq_css(sf)); + + seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable); + seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom); + seq_printf(sf, "oom_kill %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL])); + return 0; +} + +static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + /* cannot set to root cgroup and only 0 and 1 are allowed */ + if (!css->parent || !((val == 0) || (val == 1))) + return -EINVAL; + + memcg->oom_kill_disable = val; + if (!val) + memcg_oom_recover(memcg); + + return 0; +} + +#ifdef CONFIG_CGROUP_WRITEBACK + +static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) +{ + return wb_domain_init(&memcg->cgwb_domain, gfp); +} + +static void memcg_wb_domain_exit(struct mem_cgroup *memcg) +{ + wb_domain_exit(&memcg->cgwb_domain); +} + +static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg) +{ + wb_domain_size_changed(&memcg->cgwb_domain); +} + +struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); + + if (!memcg->css.parent) + return NULL; + + return &memcg->cgwb_domain; +} + +/* + * idx can be of type enum memcg_stat_item or node_stat_item. + * Keep in sync with memcg_exact_page(). + */ +static unsigned long memcg_exact_page_state(struct mem_cgroup *memcg, int idx) +{ + long x = atomic_long_read(&memcg->stat[idx]); + int cpu; + + for_each_online_cpu(cpu) + x += per_cpu_ptr(memcg->stat_cpu, cpu)->count[idx]; + if (x < 0) + x = 0; + return x; +} + +/** + * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg + * @wb: bdi_writeback in question + * @pfilepages: out parameter for number of file pages + * @pheadroom: out parameter for number of allocatable pages according to memcg + * @pdirty: out parameter for number of dirty pages + * @pwriteback: out parameter for number of pages under writeback + * + * Determine the numbers of file, headroom, dirty, and writeback pages in + * @wb's memcg. File, dirty and writeback are self-explanatory. Headroom + * is a bit more involved. + * + * A memcg's headroom is "min(max, high) - used". In the hierarchy, the + * headroom is calculated as the lowest headroom of itself and the + * ancestors. Note that this doesn't consider the actual amount of + * available memory in the system. The caller should further cap + * *@pheadroom accordingly. + */ +void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages, + unsigned long *pheadroom, unsigned long *pdirty, + unsigned long *pwriteback) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); + struct mem_cgroup *parent; + + *pdirty = memcg_exact_page_state(memcg, NR_FILE_DIRTY); + + /* this should eventually include NR_UNSTABLE_NFS */ + *pwriteback = memcg_exact_page_state(memcg, NR_WRITEBACK); + *pfilepages = mem_cgroup_nr_lru_pages(memcg, (1 << LRU_INACTIVE_FILE) | + (1 << LRU_ACTIVE_FILE)); + *pheadroom = PAGE_COUNTER_MAX; + + while ((parent = parent_mem_cgroup(memcg))) { + unsigned long ceiling = min(memcg->memory.max, memcg->high); + unsigned long used = page_counter_read(&memcg->memory); + + *pheadroom = min(*pheadroom, ceiling - min(ceiling, used)); + memcg = parent; + } +} + +#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 '<event_fd> <control_fd> <args>'. + * Interpretation of args is defined by control file implementation. + */ +static ssize_t memcg_write_event_control(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct cgroup_subsys_state *css = of_css(of); + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup_event *event; + struct cgroup_subsys_state *cfile_css; + unsigned int efd, cfd; + struct fd efile; + struct fd cfile; + const char *name; + char *endp; + int ret; + + buf = strstrip(buf); + + efd = simple_strtoul(buf, &endp, 10); + if (*endp != ' ') + return -EINVAL; + buf = endp + 1; + + cfd = simple_strtoul(buf, &endp, 10); + if ((*endp != ' ') && (*endp != '\0')) + return -EINVAL; + buf = endp + 1; + + event = kzalloc(sizeof(*event), GFP_KERNEL); + if (!event) + return -ENOMEM; + + event->memcg = memcg; + INIT_LIST_HEAD(&event->list); + init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc); + init_waitqueue_func_entry(&event->wait, memcg_event_wake); + INIT_WORK(&event->remove, memcg_event_remove); + + efile = fdget(efd); + if (!efile.file) { + ret = -EBADF; + goto out_kfree; + } + + event->eventfd = eventfd_ctx_fileget(efile.file); + if (IS_ERR(event->eventfd)) { + ret = PTR_ERR(event->eventfd); + goto out_put_efile; + } + + cfile = fdget(cfd); + if (!cfile.file) { + ret = -EBADF; + goto out_put_eventfd; + } + + /* the process need read permission on control file */ + /* AV: shouldn't we check that it's been opened for read instead? */ + ret = inode_permission(file_inode(cfile.file), MAY_READ); + if (ret < 0) + goto out_put_cfile; + + /* + * Determine the event callbacks and set them in @event. This used + * to be done via struct cftype but cgroup core no longer knows + * about these events. The following is crude but the whole thing + * is for compatibility anyway. + * + * DO NOT ADD NEW FILES. + */ + name = cfile.file->f_path.dentry->d_name.name; + + if (!strcmp(name, "memory.usage_in_bytes")) { + event->register_event = mem_cgroup_usage_register_event; + event->unregister_event = mem_cgroup_usage_unregister_event; + } else if (!strcmp(name, "memory.oom_control")) { + event->register_event = mem_cgroup_oom_register_event; + event->unregister_event = mem_cgroup_oom_unregister_event; + } else if (!strcmp(name, "memory.pressure_level")) { + event->register_event = vmpressure_register_event; + event->unregister_event = vmpressure_unregister_event; + } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) { + event->register_event = memsw_cgroup_usage_register_event; + event->unregister_event = memsw_cgroup_usage_unregister_event; + } else { + ret = -EINVAL; + goto out_put_cfile; + } + + /* + * Verify @cfile should belong to @css. Also, remaining events are + * automatically removed on cgroup destruction but the removal is + * asynchronous, so take an extra ref on @css. + */ + cfile_css = css_tryget_online_from_dir(cfile.file->f_path.dentry->d_parent, + &memory_cgrp_subsys); + ret = -EINVAL; + if (IS_ERR(cfile_css)) + goto out_put_cfile; + if (cfile_css != css) { + css_put(cfile_css); + goto out_put_cfile; + } + + ret = event->register_event(memcg, event->eventfd, buf); + if (ret) + goto out_put_css; + + vfs_poll(efile.file, &event->pt); + + spin_lock(&memcg->event_list_lock); + list_add(&event->list, &memcg->event_list); + spin_unlock(&memcg->event_list_lock); + + fdput(cfile); + fdput(efile); + + return nbytes; + +out_put_css: + css_put(css); +out_put_cfile: + fdput(cfile); +out_put_eventfd: + eventfd_ctx_put(event->eventfd); +out_put_efile: + fdput(efile); +out_kfree: + kfree(event); + + return ret; +} + +static struct cftype mem_cgroup_legacy_files[] = { + { + .name = "usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEM, RES_USAGE), + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "max_usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "limit_in_bytes", + .private = MEMFILE_PRIVATE(_MEM, RES_LIMIT), + .write = mem_cgroup_write, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "soft_limit_in_bytes", + .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), + .write = mem_cgroup_write, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "failcnt", + .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "stat", + .seq_show = memcg_stat_show, + }, + { + .name = "force_empty", + .write = mem_cgroup_force_empty_write, + }, + { + .name = "use_hierarchy", + .write_u64 = mem_cgroup_hierarchy_write, + .read_u64 = mem_cgroup_hierarchy_read, + }, + { + .name = "cgroup.event_control", /* XXX: for compat */ + .write = memcg_write_event_control, + .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE, + }, + { + .name = "swappiness", + .read_u64 = mem_cgroup_swappiness_read, + .write_u64 = mem_cgroup_swappiness_write, + }, + { + .name = "move_charge_at_immigrate", + .read_u64 = mem_cgroup_move_charge_read, + .write_u64 = mem_cgroup_move_charge_write, + }, + { + .name = "oom_control", + .seq_show = mem_cgroup_oom_control_read, + .write_u64 = mem_cgroup_oom_control_write, + .private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL), + }, + { + .name = "pressure_level", + }, +#ifdef CONFIG_NUMA + { + .name = "numa_stat", + .seq_show = memcg_numa_stat_show, + }, +#endif + { + .name = "kmem.limit_in_bytes", + .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), + .write = mem_cgroup_write, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.usage_in_bytes", + .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.failcnt", + .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.max_usage_in_bytes", + .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, +#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) + { + .name = "kmem.slabinfo", + .seq_start = memcg_slab_start, + .seq_next = memcg_slab_next, + .seq_stop = memcg_slab_stop, + .seq_show = memcg_slab_show, + }, +#endif + { + .name = "kmem.tcp.limit_in_bytes", + .private = MEMFILE_PRIVATE(_TCP, RES_LIMIT), + .write = mem_cgroup_write, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.tcp.usage_in_bytes", + .private = MEMFILE_PRIVATE(_TCP, RES_USAGE), + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.tcp.failcnt", + .private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "kmem.tcp.max_usage_in_bytes", + .private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { }, /* terminate */ +}; + +/* + * Private memory cgroup IDR + * + * Swap-out records and page cache shadow entries need to store memcg + * references in constrained space, so we maintain an ID space that is + * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of + * memory-controlled cgroups to 64k. + * + * However, there usually are many references to the oflline CSS after + * the cgroup has been destroyed, such as page cache or reclaimable + * slab objects, that don't need to hang on to the ID. We want to keep + * those dead CSS from occupying IDs, or we might quickly exhaust the + * relatively small ID space and prevent the creation of new cgroups + * even when there are much fewer than 64k cgroups - possibly none. + * + * Maintain a private 16-bit ID space for memcg, and allow the ID to + * be freed and recycled when it's no longer needed, which is usually + * when the CSS is offlined. + * + * The only exception to that are records of swapped out tmpfs/shmem + * pages that need to be attributed to live ancestors on swapin. But + * those references are manageable from userspace. + */ + +static DEFINE_IDR(mem_cgroup_idr); + +static void mem_cgroup_id_remove(struct mem_cgroup *memcg) +{ + if (memcg->id.id > 0) { + idr_remove(&mem_cgroup_idr, memcg->id.id); + memcg->id.id = 0; + } +} + +static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) +{ + VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0); + atomic_add(n, &memcg->id.ref); +} + +static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) +{ + VM_BUG_ON(atomic_read(&memcg->id.ref) < n); + if (atomic_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_get(struct mem_cgroup *memcg) +{ + mem_cgroup_id_get_many(memcg, 1); +} + +static inline void mem_cgroup_id_put(struct mem_cgroup *memcg) +{ + mem_cgroup_id_put_many(memcg, 1); +} + +/** + * mem_cgroup_from_id - look up a memcg from a memcg id + * @id: the memcg id to look up + * + * Caller must hold rcu_read_lock(). + */ +struct mem_cgroup *mem_cgroup_from_id(unsigned short id) +{ + WARN_ON_ONCE(!rcu_read_lock_held()); + return idr_find(&mem_cgroup_idr, id); +} + +static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) +{ + struct mem_cgroup_per_node *pn; + int tmp = node; + /* + * This routine is called against possible nodes. + * But it's BUG to call kmalloc() against offline node. + * + * TODO: this routine can waste much memory for nodes which will + * never be onlined. It's better to use memory hotplug callback + * function. + */ + if (!node_state(node, N_NORMAL_MEMORY)) + tmp = -1; + pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp); + if (!pn) + return 1; + + pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat); + if (!pn->lruvec_stat_cpu) { + kfree(pn); + return 1; + } + + lruvec_init(&pn->lruvec); + pn->usage_in_excess = 0; + pn->on_tree = false; + pn->memcg = memcg; + + memcg->nodeinfo[node] = pn; + return 0; +} + +static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) +{ + struct mem_cgroup_per_node *pn = memcg->nodeinfo[node]; + + if (!pn) + return; + + free_percpu(pn->lruvec_stat_cpu); + 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->stat_cpu); + 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; + size_t size; + int node; + + size = sizeof(struct mem_cgroup); + size += nr_node_ids * sizeof(struct mem_cgroup_per_node *); + + memcg = kzalloc(size, GFP_KERNEL); + if (!memcg) + return NULL; + + memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL, + 1, MEM_CGROUP_ID_MAX, + GFP_KERNEL); + if (memcg->id.id < 0) + goto fail; + + memcg->stat_cpu = alloc_percpu(struct mem_cgroup_stat_cpu); + if (!memcg->stat_cpu) + 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); + memcg->last_scanned_node = MAX_NUMNODES; + INIT_LIST_HEAD(&memcg->oom_notify); + mutex_init(&memcg->thresholds_lock); + spin_lock_init(&memcg->move_lock); + vmpressure_init(&memcg->vmpressure); + INIT_LIST_HEAD(&memcg->event_list); + spin_lock_init(&memcg->event_list_lock); + memcg->socket_pressure = jiffies; +#ifdef CONFIG_MEMCG_KMEM + memcg->kmemcg_id = -1; +#endif +#ifdef CONFIG_CGROUP_WRITEBACK + INIT_LIST_HEAD(&memcg->cgwb_list); +#endif + idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); + return memcg; +fail: + mem_cgroup_id_remove(memcg); + __mem_cgroup_free(memcg); + return NULL; +} + +static struct cgroup_subsys_state * __ref +mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) +{ + struct mem_cgroup *parent = mem_cgroup_from_css(parent_css); + struct mem_cgroup *memcg; + long error = -ENOMEM; + + memcg = mem_cgroup_alloc(); + if (!memcg) + return ERR_PTR(error); + + memcg->high = PAGE_COUNTER_MAX; + memcg->soft_limit = PAGE_COUNTER_MAX; + if (parent) { + memcg->swappiness = mem_cgroup_swappiness(parent); + memcg->oom_kill_disable = parent->oom_kill_disable; + } + if (parent && parent->use_hierarchy) { + memcg->use_hierarchy = true; + page_counter_init(&memcg->memory, &parent->memory); + page_counter_init(&memcg->swap, &parent->swap); + page_counter_init(&memcg->memsw, &parent->memsw); + page_counter_init(&memcg->kmem, &parent->kmem); + page_counter_init(&memcg->tcpmem, &parent->tcpmem); + } else { + page_counter_init(&memcg->memory, NULL); + page_counter_init(&memcg->swap, NULL); + page_counter_init(&memcg->memsw, NULL); + page_counter_init(&memcg->kmem, NULL); + page_counter_init(&memcg->tcpmem, NULL); + /* + * Deeper hierachy with use_hierarchy == false doesn't make + * much sense so let cgroup subsystem know about this + * unfortunate state in our controller. + */ + if (parent != root_mem_cgroup) + memory_cgrp_subsys.broken_hierarchy = true; + } + + /* The following stuff does not apply to the root */ + if (!parent) { + root_mem_cgroup = memcg; + return &memcg->css; + } + + error = memcg_online_kmem(memcg); + if (error) + goto fail; + + if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket) + static_branch_inc(&memcg_sockets_enabled_key); + + return &memcg->css; +fail: + mem_cgroup_id_remove(memcg); + mem_cgroup_free(memcg); + return ERR_PTR(-ENOMEM); +} + +static int mem_cgroup_css_online(struct cgroup_subsys_state *css) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + /* + * A memcg must be visible for memcg_expand_shrinker_maps() + * by the time the maps are allocated. So, we allocate maps + * here, when for_each_mem_cgroup() can't skip it. + */ + if (memcg_alloc_shrinker_maps(memcg)) { + mem_cgroup_id_remove(memcg); + return -ENOMEM; + } + + /* Online state pins memcg ID, memcg ID pins CSS */ + atomic_set(&memcg->id.ref, 1); + css_get(css); + return 0; +} + +static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + struct mem_cgroup_event *event, *tmp; + + /* + * Unregister events and notify userspace. + * Notify userspace about cgroup removing only after rmdir of cgroup + * directory to avoid race between userspace and kernelspace. + */ + spin_lock(&memcg->event_list_lock); + list_for_each_entry_safe(event, tmp, &memcg->event_list, list) { + list_del_init(&event->list); + schedule_work(&event->remove); + } + spin_unlock(&memcg->event_list_lock); + + page_counter_set_min(&memcg->memory, 0); + page_counter_set_low(&memcg->memory, 0); + + memcg_offline_kmem(memcg); + wb_memcg_offline(memcg); + + 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); + + if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket) + static_branch_dec(&memcg_sockets_enabled_key); + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_active) + static_branch_dec(&memcg_sockets_enabled_key); + + vmpressure_cleanup(&memcg->vmpressure); + cancel_work_sync(&memcg->high_work); + mem_cgroup_remove_from_trees(memcg); + memcg_free_shrinker_maps(memcg); + memcg_free_kmem(memcg); + mem_cgroup_free(memcg); +} + +/** + * mem_cgroup_css_reset - reset the states of a mem_cgroup + * @css: the target css + * + * Reset the states of the mem_cgroup associated with @css. This is + * invoked when the userland requests disabling on the default hierarchy + * but the memcg is pinned through dependency. The memcg should stop + * applying policies and should revert to the vanilla state as it may be + * made visible again. + * + * The current implementation only resets the essential configurations. + * This needs to be expanded to cover all the visible parts. + */ +static void mem_cgroup_css_reset(struct cgroup_subsys_state *css) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX); + page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX); + page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX); + page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX); + page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX); + page_counter_set_min(&memcg->memory, 0); + page_counter_set_low(&memcg->memory, 0); + memcg->high = PAGE_COUNTER_MAX; + memcg->soft_limit = PAGE_COUNTER_MAX; + memcg_wb_domain_size_changed(memcg); +} + +#ifdef CONFIG_MMU +/* Handlers for move charge at task migration. */ +static int mem_cgroup_do_precharge(unsigned long count) +{ + int ret; + + /* Try a single bulk charge without reclaim first, kswapd may wake */ + ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count); + if (!ret) { + mc.precharge += count; + return ret; + } + + /* Try charges one by one with reclaim, but do not retry */ + while (count--) { + ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1); + if (ret) + return ret; + mc.precharge++; + cond_resched(); + } + return 0; +} + +union mc_target { + struct page *page; + swp_entry_t ent; +}; + +enum mc_target_type { + MC_TARGET_NONE = 0, + MC_TARGET_PAGE, + MC_TARGET_SWAP, + MC_TARGET_DEVICE, +}; + +static struct page *mc_handle_present_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent) +{ + struct page *page = _vm_normal_page(vma, addr, ptent, true); + + 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 MEMORY_DEVICE_PRIVATE which are ZONE_DEVICE page belonging to + * a device and because they are not accessible by CPU they are store + * as special swap entry in the CPU page table. + */ + if (is_device_private_entry(ent)) { + page = device_private_entry_to_page(ent); + /* + * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have + * a refcount of 1 when free (unlike normal page) + */ + if (!page_ref_add_unless(page, 1, 1)) + return NULL; + return page; + } + + 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)); + if (do_memsw_account()) + entry->val = ent.val; + + return page; +} +#else +static struct page *mc_handle_swap_pte(struct vm_area_struct *vma, + pte_t ptent, swp_entry_t *entry) +{ + return NULL; +} +#endif + +static struct page *mc_handle_file_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent, swp_entry_t *entry) +{ + struct page *page = NULL; + struct address_space *mapping; + pgoff_t pgoff; + + if (!vma->vm_file) /* anonymous vma */ + return NULL; + if (!(mc.flags & MOVE_FILE)) + return NULL; + + mapping = vma->vm_file->f_mapping; + pgoff = linear_page_index(vma, addr); + + /* page is moved even if it's not RSS of this task(page-faulted). */ +#ifdef CONFIG_SWAP + /* shmem/tmpfs may report page out on swap: account for that too. */ + if (shmem_mapping(mapping)) { + page = find_get_entry(mapping, pgoff); + if (radix_tree_exceptional_entry(page)) { + swp_entry_t swp = radix_to_swp_entry(page); + if (do_memsw_account()) + *entry = swp; + page = find_get_page(swap_address_space(swp), + swp_offset(swp)); + } + } else + page = find_get_page(mapping, pgoff); +#else + page = find_get_page(mapping, pgoff); +#endif + return page; +} + +/** + * mem_cgroup_move_account - move account of the page + * @page: the page + * @compound: charge the page as compound or small page + * @from: mem_cgroup which the page is moved from. + * @to: mem_cgroup which the page is moved to. @from != @to. + * + * The caller must make sure the page is not on LRU (isolate_page() is useful.) + * + * This function doesn't do "charge" to new cgroup and doesn't do "uncharge" + * from old cgroup. + */ +static int mem_cgroup_move_account(struct page *page, + bool compound, + struct mem_cgroup *from, + struct mem_cgroup *to) +{ + unsigned long flags; + unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; + int ret; + bool anon; + + VM_BUG_ON(from == to); + VM_BUG_ON_PAGE(PageLRU(page), page); + VM_BUG_ON(compound && !PageTransHuge(page)); + + /* + * Prevent mem_cgroup_migrate() from looking at + * page->mem_cgroup of its source page while we change it. + */ + ret = -EBUSY; + if (!trylock_page(page)) + goto out; + + ret = -EINVAL; + if (page->mem_cgroup != from) + goto out_unlock; + + anon = PageAnon(page); + + spin_lock_irqsave(&from->move_lock, flags); + + if (!anon && page_mapped(page)) { + __mod_memcg_state(from, NR_FILE_MAPPED, -nr_pages); + __mod_memcg_state(to, NR_FILE_MAPPED, nr_pages); + } + + /* + * move_lock grabbed above and caller set from->moving_account, so + * mod_memcg_page_state will serialize updates to PageDirty. + * So mapping should be stable for dirty pages. + */ + if (!anon && PageDirty(page)) { + struct address_space *mapping = page_mapping(page); + + if (mapping_cap_account_dirty(mapping)) { + __mod_memcg_state(from, NR_FILE_DIRTY, -nr_pages); + __mod_memcg_state(to, NR_FILE_DIRTY, nr_pages); + } + } + + if (PageWriteback(page)) { + __mod_memcg_state(from, NR_WRITEBACK, -nr_pages); + __mod_memcg_state(to, NR_WRITEBACK, nr_pages); + } + + /* + * It is safe to change page->mem_cgroup here because the page + * is referenced, charged, and isolated - we can't race with + * uncharging, charging, migration, or LRU putback. + */ + + /* caller should have done css_get */ + page->mem_cgroup = to; + spin_unlock_irqrestore(&from->move_lock, flags); + + ret = 0; + + local_irq_disable(); + mem_cgroup_charge_statistics(to, page, compound, nr_pages); + memcg_check_events(to, page); + mem_cgroup_charge_statistics(from, page, compound, -nr_pages); + memcg_check_events(from, page); + local_irq_enable(); +out_unlock: + unlock_page(page); +out: + return ret; +} + +/** + * get_mctgt_type - get target type of moving charge + * @vma: the vma the pte to be checked belongs + * @addr: the address corresponding to the pte to be checked + * @ptent: the pte to be checked + * @target: the pointer the target page or swap ent will be stored(can be NULL) + * + * Returns + * 0(MC_TARGET_NONE): if the pte is not a target for move charge. + * 1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for + * move charge. if @target is not NULL, the page is stored in target->page + * with extra refcnt got(Callers should handle it). + * 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a + * target for charge migration. if @target is not NULL, the entry is stored + * in target->ent. + * 3(MC_TARGET_DEVICE): like MC_TARGET_PAGE but page is MEMORY_DEVICE_PUBLIC + * or MEMORY_DEVICE_PRIVATE (so ZONE_DEVICE page and thus not on the lru). + * For now we such page is charge like a regular page would be as for all + * intent and purposes it is just special memory taking the place of a + * regular page. + * + * See Documentations/vm/hmm.txt and include/linux/hmm.h + * + * Called with pte lock held. + */ + +static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent, union mc_target *target) +{ + struct page *page = NULL; + enum mc_target_type ret = MC_TARGET_NONE; + swp_entry_t ent = { .val = 0 }; + + if (pte_present(ptent)) + page = mc_handle_present_pte(vma, addr, ptent); + else if (is_swap_pte(ptent)) + page = mc_handle_swap_pte(vma, ptent, &ent); + else if (pte_none(ptent)) + page = mc_handle_file_pte(vma, addr, ptent, &ent); + + if (!page && !ent.val) + return ret; + if (page) { + /* + * Do only loose check w/o serialization. + * mem_cgroup_move_account() checks the page is valid or + * not under LRU exclusion. + */ + if (page->mem_cgroup == mc.from) { + ret = MC_TARGET_PAGE; + if (is_device_private_page(page) || + is_device_public_page(page)) + ret = MC_TARGET_DEVICE; + if (target) + target->page = page; + } + if (!ret || !target) + put_page(page); + } + /* + * There is a swap entry and a page doesn't exist or isn't charged. + * But we cannot move a tail-page in a THP. + */ + if (ent.val && !ret && (!page || !PageTransCompound(page)) && + mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) { + ret = MC_TARGET_SWAP; + if (target) + target->ent = ent; + } + return ret; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* + * We don't consider PMD mapped swapping or file mapped pages because THP does + * not support them for now. + * Caller should make sure that pmd_trans_huge(pmd) is true. + */ +static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd, union mc_target *target) +{ + struct page *page = NULL; + enum mc_target_type ret = MC_TARGET_NONE; + + if (unlikely(is_swap_pmd(pmd))) { + VM_BUG_ON(thp_migration_supported() && + !is_pmd_migration_entry(pmd)); + return ret; + } + page = pmd_page(pmd); + VM_BUG_ON_PAGE(!page || !PageHead(page), page); + if (!(mc.flags & MOVE_ANON)) + return ret; + if (page->mem_cgroup == mc.from) { + ret = MC_TARGET_PAGE; + if (target) { + get_page(page); + target->page = page; + } + } + return ret; +} +#else +static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd, union mc_target *target) +{ + return MC_TARGET_NONE; +} +#endif + +static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + struct vm_area_struct *vma = walk->vma; + pte_t *pte; + spinlock_t *ptl; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (ptl) { + /* + * Note their can not be MC_TARGET_DEVICE for now as we do not + * support transparent huge page with MEMORY_DEVICE_PUBLIC or + * 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 unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) +{ + unsigned long precharge; + + struct mm_walk mem_cgroup_count_precharge_walk = { + .pmd_entry = mem_cgroup_count_precharge_pte_range, + .mm = mm, + }; + down_read(&mm->mmap_sem); + walk_page_range(0, mm->highest_vm_end, + &mem_cgroup_count_precharge_walk); + up_read(&mm->mmap_sem); + + precharge = mc.precharge; + mc.precharge = 0; + + return precharge; +} + +static int mem_cgroup_precharge_mc(struct mm_struct *mm) +{ + unsigned long precharge = mem_cgroup_count_precharge(mm); + + VM_BUG_ON(mc.moving_task); + mc.moving_task = current; + return mem_cgroup_do_precharge(precharge); +} + +/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */ +static void __mem_cgroup_clear_mc(void) +{ + struct mem_cgroup *from = mc.from; + struct mem_cgroup *to = mc.to; + + /* 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); + + css_put_many(&mc.to->css, mc.moved_swap); + + mc.moved_swap = 0; + } + memcg_oom_recover(from); + memcg_oom_recover(to); + wake_up_all(&mc.waitq); +} + +static void mem_cgroup_clear_mc(void) +{ + struct mm_struct *mm = mc.mm; + + /* + * we must clear moving_task before waking up waiters at the end of + * task migration. + */ + mc.moving_task = NULL; + __mem_cgroup_clear_mc(); + spin_lock(&mc.lock); + mc.from = NULL; + mc.to = NULL; + mc.mm = NULL; + spin_unlock(&mc.lock); + + mmput(mm); +} + +static int mem_cgroup_can_attach(struct cgroup_taskset *tset) +{ + struct cgroup_subsys_state *css; + struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */ + struct mem_cgroup *from; + struct task_struct *leader, *p; + struct mm_struct *mm; + unsigned long move_flags; + int ret = 0; + + /* charge immigration isn't supported on the default hierarchy */ + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return 0; + + /* + * Multi-process migrations only happen on the default hierarchy + * where charge immigration is not used. Perform charge + * immigration if @tset contains a leader and whine if there are + * multiple. + */ + p = NULL; + cgroup_taskset_for_each_leader(leader, css, tset) { + WARN_ON_ONCE(p); + p = leader; + memcg = mem_cgroup_from_css(css); + } + if (!p) + return 0; + + /* + * We are now commited to this value whatever it is. Changes in this + * tunable will only affect upcoming migrations, not the current one. + * So we need to save it, and keep it going. + */ + move_flags = READ_ONCE(memcg->move_charge_at_immigrate); + if (!move_flags) + return 0; + + from = mem_cgroup_from_task(p); + + VM_BUG_ON(from == memcg); + + mm = get_task_mm(p); + if (!mm) + return 0; + /* We move charges only when we move a owner of the mm */ + if (mm->owner == p) { + VM_BUG_ON(mc.from); + VM_BUG_ON(mc.to); + VM_BUG_ON(mc.precharge); + VM_BUG_ON(mc.moved_charge); + VM_BUG_ON(mc.moved_swap); + + spin_lock(&mc.lock); + mc.mm = mm; + mc.from = from; + mc.to = memcg; + mc.flags = move_flags; + spin_unlock(&mc.lock); + /* We set mc.moving_task later */ + + ret = mem_cgroup_precharge_mc(mm); + if (ret) + mem_cgroup_clear_mc(); + } else { + mmput(mm); + } + return ret; +} + +static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) +{ + if (mc.to) + mem_cgroup_clear_mc(); +} + +static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + struct vm_area_struct *vma = walk->vma; + pte_t *pte; + spinlock_t *ptl; + enum mc_target_type target_type; + union mc_target target; + struct page *page; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (ptl) { + if (mc.precharge < HPAGE_PMD_NR) { + spin_unlock(ptl); + return 0; + } + target_type = get_mctgt_type_thp(vma, addr, *pmd, &target); + if (target_type == MC_TARGET_PAGE) { + page = target.page; + if (!isolate_lru_page(page)) { + if (!mem_cgroup_move_account(page, true, + mc.from, mc.to)) { + mc.precharge -= HPAGE_PMD_NR; + mc.moved_charge += HPAGE_PMD_NR; + } + putback_lru_page(page); + } + put_page(page); + } else if (target_type == MC_TARGET_DEVICE) { + page = target.page; + if (!mem_cgroup_move_account(page, true, + mc.from, mc.to)) { + mc.precharge -= HPAGE_PMD_NR; + mc.moved_charge += HPAGE_PMD_NR; + } + put_page(page); + } + spin_unlock(ptl); + return 0; + } + + if (pmd_trans_unstable(pmd)) + return 0; +retry: + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; addr += PAGE_SIZE) { + pte_t ptent = *(pte++); + bool device = false; + swp_entry_t ent; + + if (!mc.precharge) + break; + + switch (get_mctgt_type(vma, addr, ptent, &target)) { + case MC_TARGET_DEVICE: + device = true; + /* fall through */ + 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 void mem_cgroup_move_charge(void) +{ + struct mm_walk mem_cgroup_move_charge_walk = { + .pmd_entry = mem_cgroup_move_charge_pte_range, + .mm = mc.mm, + }; + + lru_add_drain_all(); + /* + * Signal lock_page_memcg() to take the memcg's move_lock + * while we're moving its pages to another memcg. Then wait + * for already started RCU-only updates to finish. + */ + atomic_inc(&mc.from->moving_account); + synchronize_rcu(); +retry: + if (unlikely(!down_read_trylock(&mc.mm->mmap_sem))) { + /* + * Someone who are holding the mmap_sem might be waiting in + * waitq. So we cancel all extra charges, wake up all waiters, + * and retry. Because we cancel precharges, we might not be able + * to move enough charges, but moving charge is a best-effort + * feature anyway, so it wouldn't be a big problem. + */ + __mem_cgroup_clear_mc(); + cond_resched(); + goto retry; + } + /* + * When we have consumed all precharges and failed in doing + * additional charge, the page walk just aborts. + */ + walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk); + + up_read(&mc.mm->mmap_sem); + atomic_dec(&mc.from->moving_account); +} + +static void mem_cgroup_move_task(void) +{ + if (mc.to) { + mem_cgroup_move_charge(); + mem_cgroup_clear_mc(); + } +} +#else /* !CONFIG_MMU */ +static int mem_cgroup_can_attach(struct cgroup_taskset *tset) +{ + return 0; +} +static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset) +{ +} +static void mem_cgroup_move_task(void) +{ +} +#endif + +/* + * Cgroup retains root cgroups across [un]mount cycles making it necessary + * to verify whether we're attached to the default hierarchy on each mount + * attempt. + */ +static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) +{ + /* + * use_hierarchy is forced on the default hierarchy. cgroup core + * guarantees that @root doesn't have any children, so turning it + * on for the root memcg is enough. + */ + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) + root_mem_cgroup->use_hierarchy = true; + else + root_mem_cgroup->use_hierarchy = false; +} + +static 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) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long min = READ_ONCE(memcg->memory.min); + + if (min == PAGE_COUNTER_MAX) + seq_puts(m, "max\n"); + else + seq_printf(m, "%llu\n", (u64)min * PAGE_SIZE); + + return 0; +} + +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) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long low = READ_ONCE(memcg->memory.low); + + if (low == PAGE_COUNTER_MAX) + seq_puts(m, "max\n"); + else + seq_printf(m, "%llu\n", (u64)low * PAGE_SIZE); + + return 0; +} + +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) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long high = READ_ONCE(memcg->high); + + if (high == PAGE_COUNTER_MAX) + seq_puts(m, "max\n"); + else + seq_printf(m, "%llu\n", (u64)high * PAGE_SIZE); + + return 0; +} + +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 long nr_pages; + unsigned long high; + int err; + + buf = strstrip(buf); + err = page_counter_memparse(buf, "max", &high); + if (err) + return err; + + memcg->high = high; + + nr_pages = page_counter_read(&memcg->memory); + if (nr_pages > high) + try_to_free_mem_cgroup_pages(memcg, nr_pages - high, + GFP_KERNEL, true); + + memcg_wb_domain_size_changed(memcg); + return nbytes; +} + +static int memory_max_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long max = READ_ONCE(memcg->memory.max); + + if (max == PAGE_COUNTER_MAX) + seq_puts(m, "max\n"); + else + seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE); + + return 0; +} + +static ssize_t memory_max_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES; + bool drained = false; + unsigned long max; + int err; + + buf = strstrip(buf); + err = page_counter_memparse(buf, "max", &max); + if (err) + return err; + + xchg(&memcg->memory.max, max); + + for (;;) { + unsigned long nr_pages = page_counter_read(&memcg->memory); + + if (nr_pages <= max) + break; + + if (signal_pending(current)) { + err = -EINTR; + 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 int memory_events_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + + seq_printf(m, "low %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_LOW])); + seq_printf(m, "high %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_HIGH])); + seq_printf(m, "max %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_MAX])); + seq_printf(m, "oom %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_OOM])); + seq_printf(m, "oom_kill %lu\n", + atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL])); + + return 0; +} + +static int memory_stat_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + struct accumulated_stats acc; + int i; + + /* + * 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: + */ + + memset(&acc, 0, sizeof(acc)); + acc.stats_size = MEMCG_NR_STAT; + acc.events_size = NR_VM_EVENT_ITEMS; + accumulate_memcg_tree(memcg, &acc); + + seq_printf(m, "anon %llu\n", + (u64)acc.stat[MEMCG_RSS] * PAGE_SIZE); + seq_printf(m, "file %llu\n", + (u64)acc.stat[MEMCG_CACHE] * PAGE_SIZE); + seq_printf(m, "kernel_stack %llu\n", + (u64)acc.stat[MEMCG_KERNEL_STACK_KB] * 1024); + seq_printf(m, "slab %llu\n", + (u64)(acc.stat[NR_SLAB_RECLAIMABLE] + + acc.stat[NR_SLAB_UNRECLAIMABLE]) * PAGE_SIZE); + seq_printf(m, "sock %llu\n", + (u64)acc.stat[MEMCG_SOCK] * PAGE_SIZE); + + seq_printf(m, "shmem %llu\n", + (u64)acc.stat[NR_SHMEM] * PAGE_SIZE); + seq_printf(m, "file_mapped %llu\n", + (u64)acc.stat[NR_FILE_MAPPED] * PAGE_SIZE); + seq_printf(m, "file_dirty %llu\n", + (u64)acc.stat[NR_FILE_DIRTY] * PAGE_SIZE); + seq_printf(m, "file_writeback %llu\n", + (u64)acc.stat[NR_WRITEBACK] * PAGE_SIZE); + + for (i = 0; i < NR_LRU_LISTS; i++) + seq_printf(m, "%s %llu\n", mem_cgroup_lru_names[i], + (u64)acc.lru_pages[i] * PAGE_SIZE); + + seq_printf(m, "slab_reclaimable %llu\n", + (u64)acc.stat[NR_SLAB_RECLAIMABLE] * PAGE_SIZE); + seq_printf(m, "slab_unreclaimable %llu\n", + (u64)acc.stat[NR_SLAB_UNRECLAIMABLE] * PAGE_SIZE); + + /* Accumulated memory events */ + + seq_printf(m, "pgfault %lu\n", acc.events[PGFAULT]); + seq_printf(m, "pgmajfault %lu\n", acc.events[PGMAJFAULT]); + + seq_printf(m, "pgrefill %lu\n", acc.events[PGREFILL]); + seq_printf(m, "pgscan %lu\n", acc.events[PGSCAN_KSWAPD] + + acc.events[PGSCAN_DIRECT]); + seq_printf(m, "pgsteal %lu\n", acc.events[PGSTEAL_KSWAPD] + + acc.events[PGSTEAL_DIRECT]); + seq_printf(m, "pgactivate %lu\n", acc.events[PGACTIVATE]); + seq_printf(m, "pgdeactivate %lu\n", acc.events[PGDEACTIVATE]); + seq_printf(m, "pglazyfree %lu\n", acc.events[PGLAZYFREE]); + seq_printf(m, "pglazyfreed %lu\n", acc.events[PGLAZYFREED]); + + seq_printf(m, "workingset_refault %lu\n", + acc.stat[WORKINGSET_REFAULT]); + seq_printf(m, "workingset_activate %lu\n", + acc.stat[WORKINGSET_ACTIVATE]); + seq_printf(m, "workingset_nodereclaim %lu\n", + acc.stat[WORKINGSET_NODERECLAIM]); + + return 0; +} + +static int memory_oom_group_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(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 = "stat", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = memory_stat_show, + }, + { + .name = "oom.group", + .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE, + .seq_show = memory_oom_group_show, + .write = memory_oom_group_write, + }, + { } /* terminate */ +}; + +struct cgroup_subsys memory_cgrp_subsys = { + .css_alloc = mem_cgroup_css_alloc, + .css_online = mem_cgroup_css_online, + .css_offline = mem_cgroup_css_offline, + .css_released = mem_cgroup_css_released, + .css_free = mem_cgroup_css_free, + .css_reset = mem_cgroup_css_reset, + .can_attach = mem_cgroup_can_attach, + .cancel_attach = mem_cgroup_cancel_attach, + .post_attach = mem_cgroup_move_task, + .bind = mem_cgroup_bind, + .dfl_cftypes = memory_files, + .legacy_cftypes = mem_cgroup_legacy_files, + .early_init = 0, +}; + +/** + * mem_cgroup_protected - check if memory consumption is in the normal range + * @root: the top ancestor of the sub-tree being checked + * @memcg: the memory cgroup to check + * + * WARNING: This function is not stateless! It can only be used as part + * of a top-down tree iteration, not for isolated queries. + * + * Returns one of the following: + * MEMCG_PROT_NONE: cgroup memory is not protected + * MEMCG_PROT_LOW: cgroup memory is protected as long there is + * an unprotected supply of reclaimable memory from other cgroups. + * MEMCG_PROT_MIN: cgroup memory is protected + * + * @root is exclusive; it is never protected when looked at directly + * + * To provide a proper hierarchical behavior, effective memory.min/low values + * are used. Below is the description of how effective memory.low is calculated. + * Effective memory.min values is calculated in the same way. + * + * Effective memory.low is always equal or less than the original memory.low. + * If there is no memory.low overcommittment (which is always true for + * top-level memory cgroups), these two values are equal. + * Otherwise, it's a part of parent's effective memory.low, + * calculated as a cgroup's memory.low usage divided by sum of sibling's + * memory.low usages, where memory.low usage is the size of actually + * protected memory. + * + * low_usage + * elow = min( memory.low, parent->elow * ------------------ ), + * siblings_low_usage + * + * | memory.current, if memory.current < memory.low + * low_usage = | + | 0, otherwise. + * + * + * Such definition of the effective memory.low provides the expected + * hierarchical behavior: parent's memory.low value is limiting + * children, unprotected memory is reclaimed first and cgroups, + * which are not using their guarantee do not affect actual memory + * distribution. + * + * For example, if there are memcgs A, A/B, A/C, A/D and A/E: + * + * A A/memory.low = 2G, A/memory.current = 6G + * //\\ + * BC DE B/memory.low = 3G B/memory.current = 2G + * C/memory.low = 1G C/memory.current = 2G + * D/memory.low = 0 D/memory.current = 2G + * E/memory.low = 10G E/memory.current = 0 + * + * and the memory pressure is applied, the following memory distribution + * is expected (approximately): + * + * A/memory.current = 2G + * + * B/memory.current = 1.3G + * C/memory.current = 0.6G + * D/memory.current = 0 + * E/memory.current = 0 + * + * These calculations require constant tracking of the actual low usages + * (see propagate_protected_usage()), as well as recursive calculation of + * effective memory.low values. But as we do call mem_cgroup_protected() + * path for each memory cgroup top-down from the reclaim, + * it's possible to optimize this part, and save calculated elow + * for next usage. This part is intentionally racy, but it's ok, + * as memory.low is a best-effort mechanism. + */ +enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, + struct mem_cgroup *memcg) +{ + struct mem_cgroup *parent; + unsigned long emin, parent_emin; + unsigned long elow, parent_elow; + unsigned long usage; + + if (mem_cgroup_disabled()) + return MEMCG_PROT_NONE; + + if (!root) + root = root_mem_cgroup; + if (memcg == root) + return MEMCG_PROT_NONE; + + usage = page_counter_read(&memcg->memory); + if (!usage) + return MEMCG_PROT_NONE; + + emin = memcg->memory.min; + elow = memcg->memory.low; + + parent = parent_mem_cgroup(memcg); + /* No parent means a non-hierarchical mode on v1 memcg */ + if (!parent) + return MEMCG_PROT_NONE; + + if (parent == root) + goto exit; + + parent_emin = READ_ONCE(parent->memory.emin); + emin = min(emin, parent_emin); + if (emin && parent_emin) { + unsigned long min_usage, siblings_min_usage; + + min_usage = min(usage, memcg->memory.min); + siblings_min_usage = atomic_long_read( + &parent->memory.children_min_usage); + + if (min_usage && siblings_min_usage) + emin = min(emin, parent_emin * min_usage / + siblings_min_usage); + } + + parent_elow = READ_ONCE(parent->memory.elow); + elow = min(elow, parent_elow); + if (elow && parent_elow) { + unsigned long low_usage, siblings_low_usage; + + low_usage = min(usage, memcg->memory.low); + siblings_low_usage = atomic_long_read( + &parent->memory.children_low_usage); + + if (low_usage && siblings_low_usage) + elow = min(elow, parent_elow * low_usage / + siblings_low_usage); + } + +exit: + memcg->memory.emin = emin; + memcg->memory.elow = elow; + + if (usage <= emin) + return MEMCG_PROT_MIN; + else if (usage <= elow) + return MEMCG_PROT_LOW; + else + return MEMCG_PROT_NONE; +} + +/** + * mem_cgroup_try_charge - try charging a page + * @page: page to charge + * @mm: mm context of the victim + * @gfp_mask: reclaim mode + * @memcgp: charged memcg return + * @compound: charge the page as compound or small page + * + * Try to charge @page to the memcg that @mm belongs to, reclaiming + * pages according to @gfp_mask if necessary. + * + * Returns 0 on success, with *@memcgp pointing to the charged memcg. + * Otherwise, an error code is returned. + * + * After page->mapping has been set up, the caller must finalize the + * charge with mem_cgroup_commit_charge(). Or abort the transaction + * with mem_cgroup_cancel_charge() in case page instantiation fails. + */ +int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm, + gfp_t gfp_mask, struct mem_cgroup **memcgp, + bool compound) +{ + struct mem_cgroup *memcg = NULL; + unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; + int ret = 0; + + if (mem_cgroup_disabled()) + goto out; + + if (PageSwapCache(page)) { + /* + * Every swap fault against a single page tries to charge the + * page, bail as early as possible. shmem_unuse() encounters + * already charged pages, too. The USED bit is protected by + * the page lock, which serializes swap cache removal, which + * in turn serializes uncharging. + */ + VM_BUG_ON_PAGE(!PageLocked(page), page); + if (compound_head(page)->mem_cgroup) + goto out; + + if (do_swap_account) { + swp_entry_t ent = { .val = page_private(page), }; + unsigned short id = lookup_swap_cgroup_id(ent); + + rcu_read_lock(); + memcg = mem_cgroup_from_id(id); + if (memcg && !css_tryget_online(&memcg->css)) + memcg = NULL; + rcu_read_unlock(); + } + } + + if (!memcg) + memcg = get_mem_cgroup_from_mm(mm); + + ret = try_charge(memcg, gfp_mask, nr_pages); + + css_put(&memcg->css); +out: + *memcgp = memcg; + return ret; +} + +int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm, + gfp_t gfp_mask, struct mem_cgroup **memcgp, + bool compound) +{ + struct mem_cgroup *memcg; + int ret; + + ret = mem_cgroup_try_charge(page, mm, gfp_mask, memcgp, compound); + memcg = *memcgp; + mem_cgroup_throttle_swaprate(memcg, page_to_nid(page), gfp_mask); + return ret; +} + +/** + * mem_cgroup_commit_charge - commit a page charge + * @page: page to charge + * @memcg: memcg to charge the page to + * @lrucare: page might be on LRU already + * @compound: charge the page as compound or small page + * + * Finalize a charge transaction started by mem_cgroup_try_charge(), + * after page->mapping has been set up. This must happen atomically + * as part of the page instantiation, i.e. under the page table lock + * for anonymous pages, under the page lock for page and swap cache. + * + * In addition, the page must not be on the LRU during the commit, to + * prevent racing with task migration. If it might be, use @lrucare. + * + * Use mem_cgroup_cancel_charge() to cancel the transaction instead. + */ +void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg, + bool lrucare, bool compound) +{ + unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; + + VM_BUG_ON_PAGE(!page->mapping, page); + VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page); + + if (mem_cgroup_disabled()) + return; + /* + * Swap faults will attempt to charge the same page multiple + * times. But reuse_swap_page() might have removed the page + * from swapcache already, so we can't check PageSwapCache(). + */ + if (!memcg) + return; + + commit_charge(page, memcg, lrucare); + + local_irq_disable(); + mem_cgroup_charge_statistics(memcg, page, compound, nr_pages); + memcg_check_events(memcg, page); + local_irq_enable(); + + if (do_memsw_account() && PageSwapCache(page)) { + swp_entry_t entry = { .val = page_private(page) }; + /* + * The swap entry might not get freed for a long time, + * let's not wait for it. The page already received a + * memory+swap charge, drop the swap entry duplicate. + */ + mem_cgroup_uncharge_swap(entry, nr_pages); + } +} + +/** + * mem_cgroup_cancel_charge - cancel a page charge + * @page: page to charge + * @memcg: memcg to charge the page to + * @compound: charge the page as compound or small page + * + * Cancel a charge transaction started by mem_cgroup_try_charge(). + */ +void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg, + bool compound) +{ + unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; + + if (mem_cgroup_disabled()) + return; + /* + * Swap faults will attempt to charge the same page multiple + * times. But reuse_swap_page() might have removed the page + * from swapcache already, so we can't check PageSwapCache(). + */ + if (!memcg) + return; + + cancel_charge(memcg, nr_pages); +} + +struct uncharge_gather { + struct mem_cgroup *memcg; + unsigned long pgpgout; + unsigned long nr_anon; + unsigned long nr_file; + unsigned long nr_kmem; + unsigned long nr_huge; + unsigned long nr_shmem; + struct page *dummy_page; +}; + +static inline void uncharge_gather_clear(struct uncharge_gather *ug) +{ + memset(ug, 0, sizeof(*ug)); +} + +static void uncharge_batch(const struct uncharge_gather *ug) +{ + unsigned long nr_pages = ug->nr_anon + ug->nr_file + ug->nr_kmem; + unsigned long flags; + + if (!mem_cgroup_is_root(ug->memcg)) { + page_counter_uncharge(&ug->memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_uncharge(&ug->memcg->memsw, nr_pages); + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && ug->nr_kmem) + page_counter_uncharge(&ug->memcg->kmem, ug->nr_kmem); + memcg_oom_recover(ug->memcg); + } + + local_irq_save(flags); + __mod_memcg_state(ug->memcg, MEMCG_RSS, -ug->nr_anon); + __mod_memcg_state(ug->memcg, MEMCG_CACHE, -ug->nr_file); + __mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge); + __mod_memcg_state(ug->memcg, NR_SHMEM, -ug->nr_shmem); + __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout); + __this_cpu_add(ug->memcg->stat_cpu->nr_page_events, nr_pages); + memcg_check_events(ug->memcg, ug->dummy_page); + local_irq_restore(flags); + + if (!mem_cgroup_is_root(ug->memcg)) + css_put_many(&ug->memcg->css, nr_pages); +} + +static void uncharge_page(struct page *page, struct uncharge_gather *ug) +{ + VM_BUG_ON_PAGE(PageLRU(page), page); + VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) && + !PageHWPoison(page) , page); + + if (!page->mem_cgroup) + return; + + /* + * Nobody should be changing or seriously looking at + * page->mem_cgroup at this point, we have fully + * exclusive access to the page. + */ + + if (ug->memcg != page->mem_cgroup) { + if (ug->memcg) { + uncharge_batch(ug); + uncharge_gather_clear(ug); + } + ug->memcg = page->mem_cgroup; + } + + if (!PageKmemcg(page)) { + unsigned int nr_pages = 1; + + if (PageTransHuge(page)) { + nr_pages <<= compound_order(page); + ug->nr_huge += nr_pages; + } + if (PageAnon(page)) + ug->nr_anon += nr_pages; + else { + ug->nr_file += nr_pages; + if (PageSwapBacked(page)) + ug->nr_shmem += nr_pages; + } + ug->pgpgout++; + } else { + ug->nr_kmem += 1 << compound_order(page); + __ClearPageKmemcg(page); + } + + ug->dummy_page = page; + page->mem_cgroup = NULL; +} + +static void uncharge_list(struct list_head *page_list) +{ + struct uncharge_gather ug; + struct list_head *next; + + uncharge_gather_clear(&ug); + + /* + * Note that the list can be a single page->lru; hence the + * do-while loop instead of a simple list_for_each_entry(). + */ + next = page_list->next; + do { + struct page *page; + + page = list_entry(next, struct page, lru); + next = page->lru.next; + + uncharge_page(page, &ug); + } while (next != page_list); + + if (ug.memcg) + uncharge_batch(&ug); +} + +/** + * mem_cgroup_uncharge - uncharge a page + * @page: page to uncharge + * + * Uncharge a page previously charged with mem_cgroup_try_charge() and + * mem_cgroup_commit_charge(). + */ +void mem_cgroup_uncharge(struct page *page) +{ + struct uncharge_gather ug; + + if (mem_cgroup_disabled()) + return; + + /* Don't touch page->lru of any random page, pre-check: */ + if (!page->mem_cgroup) + return; + + uncharge_gather_clear(&ug); + uncharge_page(page, &ug); + uncharge_batch(&ug); +} + +/** + * mem_cgroup_uncharge_list - uncharge a list of page + * @page_list: list of pages to uncharge + * + * Uncharge a list of pages previously charged with + * mem_cgroup_try_charge() and mem_cgroup_commit_charge(). + */ +void mem_cgroup_uncharge_list(struct list_head *page_list) +{ + if (mem_cgroup_disabled()) + return; + + if (!list_empty(page_list)) + uncharge_list(page_list); +} + +/** + * mem_cgroup_migrate - charge a page's replacement + * @oldpage: currently circulating page + * @newpage: replacement page + * + * Charge @newpage as a replacement page for @oldpage. @oldpage will + * be uncharged upon free. + * + * Both pages must be locked, @newpage->mapping must be set up. + */ +void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) +{ + struct mem_cgroup *memcg; + unsigned int nr_pages; + bool compound; + unsigned long flags; + + VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage); + VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); + VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage); + VM_BUG_ON_PAGE(PageTransHuge(oldpage) != PageTransHuge(newpage), + newpage); + + if (mem_cgroup_disabled()) + return; + + /* Page cache replacement: new page already charged? */ + if (newpage->mem_cgroup) + return; + + /* Swapcache readahead pages can get replaced before being charged */ + memcg = oldpage->mem_cgroup; + if (!memcg) + return; + + /* Force-charge the new page. The old one will be freed soon */ + compound = PageTransHuge(newpage); + nr_pages = compound ? hpage_nr_pages(newpage) : 1; + + page_counter_charge(&memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_charge(&memcg->memsw, nr_pages); + css_get_many(&memcg->css, nr_pages); + + commit_charge(newpage, memcg, false); + + local_irq_save(flags); + mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages); + memcg_check_events(memcg, newpage); + local_irq_restore(flags); +} + +DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key); +EXPORT_SYMBOL(memcg_sockets_enabled_key); + +void mem_cgroup_sk_alloc(struct sock *sk) +{ + struct mem_cgroup *memcg; + + if (!mem_cgroup_sockets_enabled) + return; + + /* Do not associate the sock with unrelated interrupted task's memcg. */ + if (in_interrupt()) + return; + + rcu_read_lock(); + memcg = mem_cgroup_from_task(current); + if (memcg == root_mem_cgroup) + goto out; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active) + goto out; + if (css_tryget_online(&memcg->css)) + sk->sk_memcg = memcg; +out: + rcu_read_unlock(); +} + +void mem_cgroup_sk_free(struct sock *sk) +{ + if (sk->sk_memcg) + css_put(&sk->sk_memcg->css); +} + +/** + * mem_cgroup_charge_skmem - charge socket memory + * @memcg: memcg to charge + * @nr_pages: number of pages to charge + * + * Charges @nr_pages to @memcg. Returns %true if the charge fit within + * @memcg's configured limit, %false if the charge had to be forced. + */ +bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages) +{ + gfp_t gfp_mask = GFP_KERNEL; + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) { + struct page_counter *fail; + + if (page_counter_try_charge(&memcg->tcpmem, nr_pages, &fail)) { + memcg->tcpmem_pressure = 0; + return true; + } + page_counter_charge(&memcg->tcpmem, nr_pages); + memcg->tcpmem_pressure = 1; + return false; + } + + /* Don't block in the packet receive path */ + if (in_softirq()) + gfp_mask = GFP_NOWAIT; + + mod_memcg_state(memcg, MEMCG_SOCK, nr_pages); + + if (try_charge(memcg, gfp_mask, nr_pages) == 0) + return true; + + try_charge(memcg, gfp_mask|__GFP_NOFAIL, nr_pages); + return false; +} + +/** + * mem_cgroup_uncharge_skmem - uncharge socket memory + * @memcg: memcg to uncharge + * @nr_pages: number of pages to uncharge + */ +void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages) +{ + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) { + page_counter_uncharge(&memcg->tcpmem, nr_pages); + return; + } + + mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages); + + refill_stock(memcg, nr_pages); +} + +static int __init cgroup_memory(char *s) +{ + char *token; + + while ((token = strsep(&s, ",")) != NULL) { + if (!*token) + continue; + if (!strcmp(token, "nosocket")) + cgroup_memory_nosocket = true; + if (!strcmp(token, "nokmem")) + cgroup_memory_nokmem = true; + } + return 1; +} +__setup("cgroup.memory=", cgroup_memory); + +/* + * subsys_initcall() for memory controller. + * + * Some parts like memcg_hotplug_cpu_dead() have to be initialized from this + * context because of lock dependencies (cgroup_lock -> cpu hotplug) but + * basically everything that doesn't depend on a specific mem_cgroup structure + * should be initialized from here. + */ +static int __init mem_cgroup_init(void) +{ + int cpu, node; + +#ifdef CONFIG_MEMCG_KMEM + /* + * Kmem cache creation is mostly done with the slab_mutex held, + * so use a workqueue with limited concurrency to avoid stalling + * all worker threads in case lots of cgroups are created and + * destroyed simultaneously. + */ + memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1); + BUG_ON(!memcg_kmem_cache_wq); +#endif + + cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL, + memcg_hotplug_cpu_dead); + + for_each_possible_cpu(cpu) + INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work, + drain_local_stock); + + for_each_node(node) { + struct mem_cgroup_tree_per_node *rtpn; + + rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, + node_online(node) ? node : NUMA_NO_NODE); + + rtpn->rb_root = RB_ROOT; + rtpn->rb_rightmost = NULL; + spin_lock_init(&rtpn->lock); + soft_limit_tree.rb_tree_per_node[node] = rtpn; + } + + return 0; +} +subsys_initcall(mem_cgroup_init); + +#ifdef CONFIG_MEMCG_SWAP +static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) +{ + while (!atomic_inc_not_zero(&memcg->id.ref)) { + /* + * The root cgroup cannot be destroyed, so it's refcount must + * always be >= 1. + */ + if (WARN_ON_ONCE(memcg == root_mem_cgroup)) { + VM_BUG_ON(1); + break; + } + memcg = parent_mem_cgroup(memcg); + if (!memcg) + memcg = root_mem_cgroup; + } + return memcg; +} + +/** + * mem_cgroup_swapout - transfer a memsw charge to swap + * @page: page whose memsw charge to transfer + * @entry: swap entry to move the charge to + * + * Transfer the memsw charge of @page to @entry. + */ +void mem_cgroup_swapout(struct page *page, swp_entry_t entry) +{ + struct mem_cgroup *memcg, *swap_memcg; + unsigned int nr_entries; + unsigned short oldid; + + VM_BUG_ON_PAGE(PageLRU(page), page); + VM_BUG_ON_PAGE(page_count(page), page); + + if (!do_memsw_account()) + return; + + memcg = page->mem_cgroup; + + /* Readahead page, never charged */ + if (!memcg) + return; + + /* + * In case the memcg owning these pages has been offlined and doesn't + * have an ID allocated to it anymore, charge the closest online + * ancestor for the swap instead and transfer the memory+swap charge. + */ + swap_memcg = mem_cgroup_id_get_online(memcg); + nr_entries = hpage_nr_pages(page); + /* Get references for the tail pages, too */ + if (nr_entries > 1) + mem_cgroup_id_get_many(swap_memcg, nr_entries - 1); + oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg), + nr_entries); + VM_BUG_ON_PAGE(oldid, page); + mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries); + + page->mem_cgroup = NULL; + + if (!mem_cgroup_is_root(memcg)) + page_counter_uncharge(&memcg->memory, nr_entries); + + if (memcg != swap_memcg) { + if (!mem_cgroup_is_root(swap_memcg)) + page_counter_charge(&swap_memcg->memsw, nr_entries); + page_counter_uncharge(&memcg->memsw, nr_entries); + } + + /* + * Interrupts should be disabled here because the caller holds the + * i_pages lock which is taken with interrupts-off. It is + * important here to have the interrupts disabled because it is the + * only synchronisation we have for updating the per-CPU variables. + */ + VM_BUG_ON(!irqs_disabled()); + mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page), + -nr_entries); + memcg_check_events(memcg, page); + + if (!mem_cgroup_is_root(memcg)) + css_put_many(&memcg->css, nr_entries); +} + +/** + * mem_cgroup_try_charge_swap - try charging swap space for a page + * @page: page being added to swap + * @entry: swap entry to charge + * + * Try to charge @page's memcg for the swap space at @entry. + * + * Returns 0 on success, -ENOMEM on failure. + */ +int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) +{ + unsigned int nr_pages = hpage_nr_pages(page); + struct page_counter *counter; + struct mem_cgroup *memcg; + unsigned short oldid; + + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account) + return 0; + + memcg = page->mem_cgroup; + + /* Readahead page, never charged */ + if (!memcg) + return 0; + + if (!entry.val) { + memcg_memory_event(memcg, MEMCG_SWAP_FAIL); + return 0; + } + + memcg = mem_cgroup_id_get_online(memcg); + + if (!mem_cgroup_is_root(memcg) && + !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) { + memcg_memory_event(memcg, MEMCG_SWAP_MAX); + memcg_memory_event(memcg, MEMCG_SWAP_FAIL); + mem_cgroup_id_put(memcg); + return -ENOMEM; + } + + /* Get references for the tail pages, too */ + if (nr_pages > 1) + mem_cgroup_id_get_many(memcg, nr_pages - 1); + oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages); + VM_BUG_ON_PAGE(oldid, page); + mod_memcg_state(memcg, MEMCG_SWAP, nr_pages); + + return 0; +} + +/** + * mem_cgroup_uncharge_swap - uncharge swap space + * @entry: swap entry to uncharge + * @nr_pages: the amount of swap space to uncharge + */ +void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) +{ + struct mem_cgroup *memcg; + unsigned short id; + + if (!do_swap_account) + return; + + id = swap_cgroup_record(entry, 0, nr_pages); + rcu_read_lock(); + memcg = mem_cgroup_from_id(id); + if (memcg) { + if (!mem_cgroup_is_root(memcg)) { + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) + page_counter_uncharge(&memcg->swap, nr_pages); + else + page_counter_uncharge(&memcg->memsw, nr_pages); + } + mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages); + mem_cgroup_id_put_many(memcg, nr_pages); + } + rcu_read_unlock(); +} + +long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) +{ + long nr_swap_pages = get_nr_swap_pages(); + + if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return nr_swap_pages; + for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) + nr_swap_pages = min_t(long, nr_swap_pages, + READ_ONCE(memcg->swap.max) - + page_counter_read(&memcg->swap)); + return nr_swap_pages; +} + +bool mem_cgroup_swap_full(struct page *page) +{ + struct mem_cgroup *memcg; + + VM_BUG_ON_PAGE(!PageLocked(page), page); + + if (vm_swap_full()) + return true; + if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return false; + + memcg = page->mem_cgroup; + if (!memcg) + return false; + + for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) + if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max) + return true; + + return false; +} + +/* for remember boot option*/ +#ifdef CONFIG_MEMCG_SWAP_ENABLED +static int really_do_swap_account __initdata = 1; +#else +static int really_do_swap_account __initdata; +#endif + +static int __init enable_swap_account(char *s) +{ + if (!strcmp(s, "1")) + really_do_swap_account = 1; + else if (!strcmp(s, "0")) + really_do_swap_account = 0; + return 1; +} +__setup("swapaccount=", enable_swap_account); + +static u64 swap_current_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(css); + + return (u64)page_counter_read(&memcg->swap) * PAGE_SIZE; +} + +static int swap_max_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + unsigned long max = READ_ONCE(memcg->swap.max); + + if (max == PAGE_COUNTER_MAX) + seq_puts(m, "max\n"); + else + seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE); + + return 0; +} + +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_css(seq_css(m)); + + 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.max", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = swap_max_show, + .write = swap_max_write, + }, + { + .name = "swap.events", + .flags = CFTYPE_NOT_ON_ROOT, + .file_offset = offsetof(struct mem_cgroup, swap_events_file), + .seq_show = swap_events_show, + }, + { } /* terminate */ +}; + +static struct cftype memsw_cgroup_files[] = { + { + .name = "memsw.usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "memsw.max_usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "memsw.limit_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), + .write = mem_cgroup_write, + .read_u64 = mem_cgroup_read_u64, + }, + { + .name = "memsw.failcnt", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), + .write = mem_cgroup_reset, + .read_u64 = mem_cgroup_read_u64, + }, + { }, /* terminate */ +}; + +static int __init mem_cgroup_swap_init(void) +{ + if (!mem_cgroup_disabled() && really_do_swap_account) { + do_swap_account = 1; + WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, + swap_files)); + WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, + memsw_cgroup_files)); + } + return 0; +} +subsys_initcall(mem_cgroup_swap_init); + +#endif /* CONFIG_MEMCG_SWAP */ |