| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* 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 |
| * |
| * Per memcg lru locking |
| * Copyright (C) 2020 Alibaba, Inc, Alex Shi |
| */ |
| |
| #include <linux/page_counter.h> |
| #include <linux/memcontrol.h> |
| #include <linux/cgroup.h> |
| #include <linux/pagewalk.h> |
| #include <linux/sched/mm.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/hugetlb.h> |
| #include <linux/pagemap.h> |
| #include <linux/pagevec.h> |
| #include <linux/vm_event_item.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/memremap.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/resume_user_mode.h> |
| #include <linux/psi.h> |
| #include <linux/seq_buf.h> |
| #include <linux/sched/isolation.h> |
| #include <linux/kmemleak.h> |
| #include "internal.h" |
| #include <net/sock.h> |
| #include <net/ip.h> |
| #include "slab.h" |
| #include "swap.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; |
| |
| /* Active memory cgroup to use from an interrupt context */ |
| DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg); |
| EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg); |
| |
| /* Socket memory accounting disabled? */ |
| static bool cgroup_memory_nosocket __ro_after_init; |
| |
| /* Kernel memory accounting disabled? */ |
| static bool cgroup_memory_nokmem __ro_after_init; |
| |
| /* BPF memory accounting disabled? */ |
| static bool cgroup_memory_nobpf __ro_after_init; |
| |
| #ifdef CONFIG_CGROUP_WRITEBACK |
| static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq); |
| #endif |
| |
| /* Whether legacy memory+swap accounting is active */ |
| static bool do_memsw_account(void) |
| { |
| return !cgroup_subsys_on_dfl(memory_cgrp_subsys); |
| } |
| |
| #define THRESHOLDS_EVENTS_TARGET 128 |
| #define SOFTLIMIT_EVENTS_TARGET 1024 |
| |
| /* |
| * Cgroups above their limits are maintained in a RB-Tree, independent of |
| * their hierarchy representation |
| */ |
| |
| struct mem_cgroup_tree_per_node { |
| struct rb_root rb_root; |
| struct rb_node *rb_rightmost; |
| spinlock_t lock; |
| }; |
| |
| struct mem_cgroup_tree { |
| struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES]; |
| }; |
| |
| static struct mem_cgroup_tree soft_limit_tree __read_mostly; |
| |
| /* for OOM */ |
| struct mem_cgroup_eventfd_list { |
| struct list_head list; |
| struct eventfd_ctx *eventfd; |
| }; |
| |
| /* |
| * cgroup_event represents events which userspace want to receive. |
| */ |
| struct mem_cgroup_event { |
| /* |
| * memcg which the event belongs to. |
| */ |
| struct mem_cgroup *memcg; |
| /* |
| * eventfd to signal userspace about the event. |
| */ |
| struct eventfd_ctx *eventfd; |
| /* |
| * Each of these stored in a list by the cgroup. |
| */ |
| struct list_head list; |
| /* |
| * register_event() callback will be used to add new userspace |
| * waiter for changes related to this event. Use eventfd_signal() |
| * on eventfd to send notification to userspace. |
| */ |
| int (*register_event)(struct mem_cgroup *memcg, |
| struct eventfd_ctx *eventfd, const char *args); |
| /* |
| * unregister_event() callback will be called when userspace closes |
| * the eventfd or on cgroup removing. This callback must be set, |
| * if you want provide notification functionality. |
| */ |
| void (*unregister_event)(struct mem_cgroup *memcg, |
| struct eventfd_ctx *eventfd); |
| /* |
| * All fields below needed to unregister event when |
| * userspace closes eventfd. |
| */ |
| poll_table pt; |
| wait_queue_head_t *wqh; |
| wait_queue_entry_t wait; |
| struct work_struct remove; |
| }; |
| |
| static void mem_cgroup_threshold(struct mem_cgroup *memcg); |
| static void mem_cgroup_oom_notify(struct mem_cgroup *memcg); |
| |
| /* Stuffs for move charges at task migration. */ |
| /* |
| * Types of charges to be moved. |
| */ |
| #define MOVE_ANON 0x1U |
| #define MOVE_FILE 0x2U |
| #define MOVE_MASK (MOVE_ANON | MOVE_FILE) |
| |
| /* "mc" and its members are protected by cgroup_mutex */ |
| static struct move_charge_struct { |
| spinlock_t lock; /* for from, to */ |
| struct mm_struct *mm; |
| struct mem_cgroup *from; |
| struct mem_cgroup *to; |
| unsigned long flags; |
| unsigned long precharge; |
| unsigned long moved_charge; |
| unsigned long moved_swap; |
| struct task_struct *moving_task; /* a task moving charges */ |
| wait_queue_head_t waitq; /* a waitq for other context */ |
| } mc = { |
| .lock = __SPIN_LOCK_UNLOCKED(mc.lock), |
| .waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq), |
| }; |
| |
| /* |
| * Maximum loops in mem_cgroup_soft_reclaim(), used for soft |
| * limit reclaim to prevent infinite loops, if they ever occur. |
| */ |
| #define MEM_CGROUP_MAX_RECLAIM_LOOPS 100 |
| #define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS 2 |
| |
| /* for encoding cft->private value on file */ |
| enum res_type { |
| _MEM, |
| _MEMSWAP, |
| _KMEM, |
| _TCP, |
| }; |
| |
| #define MEMFILE_PRIVATE(x, val) ((x) << 16 | (val)) |
| #define MEMFILE_TYPE(val) ((val) >> 16 & 0xffff) |
| #define MEMFILE_ATTR(val) ((val) & 0xffff) |
| |
| /* |
| * Iteration constructs for visiting all cgroups (under a tree). If |
| * loops are exited prematurely (break), mem_cgroup_iter_break() must |
| * be used for reference counting. |
| */ |
| #define for_each_mem_cgroup_tree(iter, root) \ |
| for (iter = mem_cgroup_iter(root, NULL, NULL); \ |
| iter != NULL; \ |
| iter = mem_cgroup_iter(root, iter, NULL)) |
| |
| #define for_each_mem_cgroup(iter) \ |
| for (iter = mem_cgroup_iter(NULL, NULL, NULL); \ |
| iter != NULL; \ |
| iter = mem_cgroup_iter(NULL, iter, NULL)) |
| |
| static inline bool task_is_dying(void) |
| { |
| return tsk_is_oom_victim(current) || fatal_signal_pending(current) || |
| (current->flags & PF_EXITING); |
| } |
| |
| /* Some nice accessors for the vmpressure. */ |
| struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg) |
| { |
| if (!memcg) |
| memcg = root_mem_cgroup; |
| return &memcg->vmpressure; |
| } |
| |
| struct mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr) |
| { |
| return container_of(vmpr, struct mem_cgroup, vmpressure); |
| } |
| |
| #define CURRENT_OBJCG_UPDATE_BIT 0 |
| #define CURRENT_OBJCG_UPDATE_FLAG (1UL << CURRENT_OBJCG_UPDATE_BIT) |
| |
| #ifdef CONFIG_MEMCG_KMEM |
| static DEFINE_SPINLOCK(objcg_lock); |
| |
| bool mem_cgroup_kmem_disabled(void) |
| { |
| return cgroup_memory_nokmem; |
| } |
| |
| static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, |
| unsigned int nr_pages); |
| |
| static void obj_cgroup_release(struct percpu_ref *ref) |
| { |
| struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt); |
| unsigned int nr_bytes; |
| unsigned int nr_pages; |
| unsigned long flags; |
| |
| /* |
| * At this point all allocated objects are freed, and |
| * objcg->nr_charged_bytes can't have an arbitrary byte value. |
| * However, it can be PAGE_SIZE or (x * PAGE_SIZE). |
| * |
| * The following sequence can lead to it: |
| * 1) CPU0: objcg == stock->cached_objcg |
| * 2) CPU1: we do a small allocation (e.g. 92 bytes), |
| * PAGE_SIZE bytes are charged |
| * 3) CPU1: a process from another memcg is allocating something, |
| * the stock if flushed, |
| * objcg->nr_charged_bytes = PAGE_SIZE - 92 |
| * 5) CPU0: we do release this object, |
| * 92 bytes are added to stock->nr_bytes |
| * 6) CPU0: stock is flushed, |
| * 92 bytes are added to objcg->nr_charged_bytes |
| * |
| * In the result, nr_charged_bytes == PAGE_SIZE. |
| * This page will be uncharged in obj_cgroup_release(). |
| */ |
| nr_bytes = atomic_read(&objcg->nr_charged_bytes); |
| WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1)); |
| nr_pages = nr_bytes >> PAGE_SHIFT; |
| |
| if (nr_pages) |
| obj_cgroup_uncharge_pages(objcg, nr_pages); |
| |
| spin_lock_irqsave(&objcg_lock, flags); |
| list_del(&objcg->list); |
| spin_unlock_irqrestore(&objcg_lock, flags); |
| |
| percpu_ref_exit(ref); |
| kfree_rcu(objcg, rcu); |
| } |
| |
| static struct obj_cgroup *obj_cgroup_alloc(void) |
| { |
| struct obj_cgroup *objcg; |
| int ret; |
| |
| objcg = kzalloc(sizeof(struct obj_cgroup), GFP_KERNEL); |
| if (!objcg) |
| return NULL; |
| |
| ret = percpu_ref_init(&objcg->refcnt, obj_cgroup_release, 0, |
| GFP_KERNEL); |
| if (ret) { |
| kfree(objcg); |
| return NULL; |
| } |
| INIT_LIST_HEAD(&objcg->list); |
| return objcg; |
| } |
| |
| static void memcg_reparent_objcgs(struct mem_cgroup *memcg, |
| struct mem_cgroup *parent) |
| { |
| struct obj_cgroup *objcg, *iter; |
| |
| objcg = rcu_replace_pointer(memcg->objcg, NULL, true); |
| |
| spin_lock_irq(&objcg_lock); |
| |
| /* 1) Ready to reparent active objcg. */ |
| list_add(&objcg->list, &memcg->objcg_list); |
| /* 2) Reparent active objcg and already reparented objcgs to parent. */ |
| list_for_each_entry(iter, &memcg->objcg_list, list) |
| WRITE_ONCE(iter->memcg, parent); |
| /* 3) Move already reparented objcgs to the parent's list */ |
| list_splice(&memcg->objcg_list, &parent->objcg_list); |
| |
| spin_unlock_irq(&objcg_lock); |
| |
| percpu_ref_kill(&objcg->refcnt); |
| } |
| |
| /* |
| * A lot of the calls to the cache allocation functions are expected to be |
| * inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are |
| * conditional to this static branch, we'll have to allow modules that does |
| * kmem_cache_alloc and the such to see this symbol as well |
| */ |
| DEFINE_STATIC_KEY_FALSE(memcg_kmem_online_key); |
| EXPORT_SYMBOL(memcg_kmem_online_key); |
| |
| DEFINE_STATIC_KEY_FALSE(memcg_bpf_enabled_key); |
| EXPORT_SYMBOL(memcg_bpf_enabled_key); |
| #endif |
| |
| /** |
| * mem_cgroup_css_from_folio - css of the memcg associated with a folio |
| * @folio: folio of interest |
| * |
| * If memcg is bound to the default hierarchy, css of the memcg associated |
| * with @folio is returned. The returned css remains associated with @folio |
| * 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_folio(struct folio *folio) |
| { |
| struct mem_cgroup *memcg = folio_memcg(folio); |
| |
| 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(); |
| /* page_folio() is racy here, but the entire function is racy anyway */ |
| memcg = folio_memcg_check(page_folio(page)); |
| |
| while (memcg && !(memcg->css.flags & CSS_ONLINE)) |
| memcg = parent_mem_cgroup(memcg); |
| if (memcg) |
| ino = cgroup_ino(memcg->css.cgroup); |
| rcu_read_unlock(); |
| return ino; |
| } |
| |
| static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, |
| struct mem_cgroup_tree_per_node *mctz, |
| unsigned long new_usage_in_excess) |
| { |
| struct rb_node **p = &mctz->rb_root.rb_node; |
| struct rb_node *parent = NULL; |
| struct mem_cgroup_per_node *mz_node; |
| bool rightmost = true; |
| |
| if (mz->on_tree) |
| return; |
| |
| mz->usage_in_excess = new_usage_in_excess; |
| if (!mz->usage_in_excess) |
| return; |
| while (*p) { |
| parent = *p; |
| mz_node = rb_entry(parent, struct mem_cgroup_per_node, |
| tree_node); |
| if (mz->usage_in_excess < mz_node->usage_in_excess) { |
| p = &(*p)->rb_left; |
| rightmost = false; |
| } else { |
| p = &(*p)->rb_right; |
| } |
| } |
| |
| if (rightmost) |
| mctz->rb_rightmost = &mz->tree_node; |
| |
| rb_link_node(&mz->tree_node, parent, p); |
| rb_insert_color(&mz->tree_node, &mctz->rb_root); |
| mz->on_tree = true; |
| } |
| |
| static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, |
| struct mem_cgroup_tree_per_node *mctz) |
| { |
| if (!mz->on_tree) |
| return; |
| |
| if (&mz->tree_node == mctz->rb_rightmost) |
| mctz->rb_rightmost = rb_prev(&mz->tree_node); |
| |
| rb_erase(&mz->tree_node, &mctz->rb_root); |
| mz->on_tree = false; |
| } |
| |
| static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz, |
| struct mem_cgroup_tree_per_node *mctz) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&mctz->lock, flags); |
| __mem_cgroup_remove_exceeded(mz, mctz); |
| spin_unlock_irqrestore(&mctz->lock, flags); |
| } |
| |
| static unsigned long soft_limit_excess(struct mem_cgroup *memcg) |
| { |
| unsigned long nr_pages = page_counter_read(&memcg->memory); |
| unsigned long soft_limit = READ_ONCE(memcg->soft_limit); |
| unsigned long excess = 0; |
| |
| if (nr_pages > soft_limit) |
| excess = nr_pages - soft_limit; |
| |
| return excess; |
| } |
| |
| static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid) |
| { |
| unsigned long excess; |
| struct mem_cgroup_per_node *mz; |
| struct mem_cgroup_tree_per_node *mctz; |
| |
| if (lru_gen_enabled()) { |
| if (soft_limit_excess(memcg)) |
| lru_gen_soft_reclaim(memcg, nid); |
| return; |
| } |
| |
| mctz = soft_limit_tree.rb_tree_per_node[nid]; |
| if (!mctz) |
| return; |
| /* |
| * Necessary to update all ancestors when hierarchy is used. |
| * because their event counter is not touched. |
| */ |
| for (; memcg; memcg = parent_mem_cgroup(memcg)) { |
| mz = memcg->nodeinfo[nid]; |
| excess = soft_limit_excess(memcg); |
| /* |
| * We have to update the tree if mz is on RB-tree or |
| * mem is over its softlimit. |
| */ |
| if (excess || mz->on_tree) { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&mctz->lock, flags); |
| /* if on-tree, remove it */ |
| if (mz->on_tree) |
| __mem_cgroup_remove_exceeded(mz, mctz); |
| /* |
| * Insert again. mz->usage_in_excess will be updated. |
| * If excess is 0, no tree ops. |
| */ |
| __mem_cgroup_insert_exceeded(mz, mctz, excess); |
| spin_unlock_irqrestore(&mctz->lock, flags); |
| } |
| } |
| } |
| |
| static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup_tree_per_node *mctz; |
| struct mem_cgroup_per_node *mz; |
| int nid; |
| |
| for_each_node(nid) { |
| mz = memcg->nodeinfo[nid]; |
| mctz = soft_limit_tree.rb_tree_per_node[nid]; |
| if (mctz) |
| mem_cgroup_remove_exceeded(mz, mctz); |
| } |
| } |
| |
| static struct mem_cgroup_per_node * |
| __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) |
| { |
| struct mem_cgroup_per_node *mz; |
| |
| retry: |
| mz = NULL; |
| if (!mctz->rb_rightmost) |
| goto done; /* Nothing to reclaim from */ |
| |
| mz = rb_entry(mctz->rb_rightmost, |
| struct mem_cgroup_per_node, tree_node); |
| /* |
| * Remove the node now but someone else can add it back, |
| * we will to add it back at the end of reclaim to its correct |
| * position in the tree. |
| */ |
| __mem_cgroup_remove_exceeded(mz, mctz); |
| if (!soft_limit_excess(mz->memcg) || |
| !css_tryget(&mz->memcg->css)) |
| goto retry; |
| done: |
| return mz; |
| } |
| |
| static struct mem_cgroup_per_node * |
| mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) |
| { |
| struct mem_cgroup_per_node *mz; |
| |
| spin_lock_irq(&mctz->lock); |
| mz = __mem_cgroup_largest_soft_limit_node(mctz); |
| spin_unlock_irq(&mctz->lock); |
| return mz; |
| } |
| |
| /* Subset of vm_event_item to report for memcg event stats */ |
| static const unsigned int memcg_vm_event_stat[] = { |
| PGPGIN, |
| PGPGOUT, |
| PGSCAN_KSWAPD, |
| PGSCAN_DIRECT, |
| PGSCAN_KHUGEPAGED, |
| PGSTEAL_KSWAPD, |
| PGSTEAL_DIRECT, |
| PGSTEAL_KHUGEPAGED, |
| PGFAULT, |
| PGMAJFAULT, |
| PGREFILL, |
| PGACTIVATE, |
| PGDEACTIVATE, |
| PGLAZYFREE, |
| PGLAZYFREED, |
| #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP) |
| ZSWPIN, |
| ZSWPOUT, |
| ZSWPWB, |
| #endif |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| THP_FAULT_ALLOC, |
| THP_COLLAPSE_ALLOC, |
| THP_SWPOUT, |
| THP_SWPOUT_FALLBACK, |
| #endif |
| }; |
| |
| #define NR_MEMCG_EVENTS ARRAY_SIZE(memcg_vm_event_stat) |
| static int mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; |
| |
| static void init_memcg_events(void) |
| { |
| int i; |
| |
| for (i = 0; i < NR_MEMCG_EVENTS; ++i) |
| mem_cgroup_events_index[memcg_vm_event_stat[i]] = i + 1; |
| } |
| |
| static inline int memcg_events_index(enum vm_event_item idx) |
| { |
| return mem_cgroup_events_index[idx] - 1; |
| } |
| |
| struct memcg_vmstats_percpu { |
| /* Stats updates since the last flush */ |
| unsigned int stats_updates; |
| |
| /* Cached pointers for fast iteration in memcg_rstat_updated() */ |
| struct memcg_vmstats_percpu *parent; |
| struct memcg_vmstats *vmstats; |
| |
| /* The above should fit a single cacheline for memcg_rstat_updated() */ |
| |
| /* Local (CPU and cgroup) page state & events */ |
| long state[MEMCG_NR_STAT]; |
| unsigned long events[NR_MEMCG_EVENTS]; |
| |
| /* Delta calculation for lockless upward propagation */ |
| long state_prev[MEMCG_NR_STAT]; |
| unsigned long events_prev[NR_MEMCG_EVENTS]; |
| |
| /* Cgroup1: threshold notifications & softlimit tree updates */ |
| unsigned long nr_page_events; |
| unsigned long targets[MEM_CGROUP_NTARGETS]; |
| } ____cacheline_aligned; |
| |
| struct memcg_vmstats { |
| /* Aggregated (CPU and subtree) page state & events */ |
| long state[MEMCG_NR_STAT]; |
| unsigned long events[NR_MEMCG_EVENTS]; |
| |
| /* Non-hierarchical (CPU aggregated) page state & events */ |
| long state_local[MEMCG_NR_STAT]; |
| unsigned long events_local[NR_MEMCG_EVENTS]; |
| |
| /* Pending child counts during tree propagation */ |
| long state_pending[MEMCG_NR_STAT]; |
| unsigned long events_pending[NR_MEMCG_EVENTS]; |
| |
| /* Stats updates since the last flush */ |
| atomic64_t stats_updates; |
| }; |
| |
| /* |
| * memcg and lruvec stats flushing |
| * |
| * Many codepaths leading to stats update or read are performance sensitive and |
| * adding stats flushing in such codepaths is not desirable. So, to optimize the |
| * flushing the kernel does: |
| * |
| * 1) Periodically and asynchronously flush the stats every 2 seconds to not let |
| * rstat update tree grow unbounded. |
| * |
| * 2) Flush the stats synchronously on reader side only when there are more than |
| * (MEMCG_CHARGE_BATCH * nr_cpus) update events. Though this optimization |
| * will let stats be out of sync by atmost (MEMCG_CHARGE_BATCH * nr_cpus) but |
| * only for 2 seconds due to (1). |
| */ |
| static void flush_memcg_stats_dwork(struct work_struct *w); |
| static DECLARE_DEFERRABLE_WORK(stats_flush_dwork, flush_memcg_stats_dwork); |
| static u64 flush_last_time; |
| |
| #define FLUSH_TIME (2UL*HZ) |
| |
| /* |
| * Accessors to ensure that preemption is disabled on PREEMPT_RT because it can |
| * not rely on this as part of an acquired spinlock_t lock. These functions are |
| * never used in hardirq context on PREEMPT_RT and therefore disabling preemtion |
| * is sufficient. |
| */ |
| static void memcg_stats_lock(void) |
| { |
| preempt_disable_nested(); |
| VM_WARN_ON_IRQS_ENABLED(); |
| } |
| |
| static void __memcg_stats_lock(void) |
| { |
| preempt_disable_nested(); |
| } |
| |
| static void memcg_stats_unlock(void) |
| { |
| preempt_enable_nested(); |
| } |
| |
| |
| static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) |
| { |
| return atomic64_read(&vmstats->stats_updates) > |
| MEMCG_CHARGE_BATCH * num_online_cpus(); |
| } |
| |
| static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) |
| { |
| struct memcg_vmstats_percpu *statc; |
| int cpu = smp_processor_id(); |
| |
| if (!val) |
| return; |
| |
| cgroup_rstat_updated(memcg->css.cgroup, cpu); |
| statc = this_cpu_ptr(memcg->vmstats_percpu); |
| for (; statc; statc = statc->parent) { |
| statc->stats_updates += abs(val); |
| if (statc->stats_updates < MEMCG_CHARGE_BATCH) |
| continue; |
| |
| /* |
| * If @memcg is already flush-able, increasing stats_updates is |
| * redundant. Avoid the overhead of the atomic update. |
| */ |
| if (!memcg_vmstats_needs_flush(statc->vmstats)) |
| atomic64_add(statc->stats_updates, |
| &statc->vmstats->stats_updates); |
| statc->stats_updates = 0; |
| } |
| } |
| |
| static void do_flush_stats(struct mem_cgroup *memcg) |
| { |
| if (mem_cgroup_is_root(memcg)) |
| WRITE_ONCE(flush_last_time, jiffies_64); |
| |
| cgroup_rstat_flush(memcg->css.cgroup); |
| } |
| |
| /* |
| * mem_cgroup_flush_stats - flush the stats of a memory cgroup subtree |
| * @memcg: root of the subtree to flush |
| * |
| * Flushing is serialized by the underlying global rstat lock. There is also a |
| * minimum amount of work to be done even if there are no stat updates to flush. |
| * Hence, we only flush the stats if the updates delta exceeds a threshold. This |
| * avoids unnecessary work and contention on the underlying lock. |
| */ |
| void mem_cgroup_flush_stats(struct mem_cgroup *memcg) |
| { |
| if (mem_cgroup_disabled()) |
| return; |
| |
| if (!memcg) |
| memcg = root_mem_cgroup; |
| |
| if (memcg_vmstats_needs_flush(memcg->vmstats)) |
| do_flush_stats(memcg); |
| } |
| |
| void mem_cgroup_flush_stats_ratelimited(struct mem_cgroup *memcg) |
| { |
| /* Only flush if the periodic flusher is one full cycle late */ |
| if (time_after64(jiffies_64, READ_ONCE(flush_last_time) + 2*FLUSH_TIME)) |
| mem_cgroup_flush_stats(memcg); |
| } |
| |
| static void flush_memcg_stats_dwork(struct work_struct *w) |
| { |
| /* |
| * Deliberately ignore memcg_vmstats_needs_flush() here so that flushing |
| * in latency-sensitive paths is as cheap as possible. |
| */ |
| do_flush_stats(root_mem_cgroup); |
| queue_delayed_work(system_unbound_wq, &stats_flush_dwork, FLUSH_TIME); |
| } |
| |
| unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) |
| { |
| long x = READ_ONCE(memcg->vmstats->state[idx]); |
| #ifdef CONFIG_SMP |
| if (x < 0) |
| x = 0; |
| #endif |
| return x; |
| } |
| |
| static int memcg_page_state_unit(int item); |
| |
| /* |
| * Normalize the value passed into memcg_rstat_updated() to be in pages. Round |
| * up non-zero sub-page updates to 1 page as zero page updates are ignored. |
| */ |
| static int memcg_state_val_in_pages(int idx, int val) |
| { |
| int unit = memcg_page_state_unit(idx); |
| |
| if (!val || unit == PAGE_SIZE) |
| return val; |
| else |
| return max(val * unit / PAGE_SIZE, 1UL); |
| } |
| |
| /** |
| * __mod_memcg_state - update cgroup memory statistics |
| * @memcg: the memory cgroup |
| * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item |
| * @val: delta to add to the counter, can be negative |
| */ |
| void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val) |
| { |
| if (mem_cgroup_disabled()) |
| return; |
| |
| __this_cpu_add(memcg->vmstats_percpu->state[idx], val); |
| memcg_rstat_updated(memcg, memcg_state_val_in_pages(idx, val)); |
| } |
| |
| /* idx can be of type enum memcg_stat_item or node_stat_item. */ |
| static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) |
| { |
| long x = READ_ONCE(memcg->vmstats->state_local[idx]); |
| |
| #ifdef CONFIG_SMP |
| if (x < 0) |
| x = 0; |
| #endif |
| return x; |
| } |
| |
| void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, |
| int val) |
| { |
| struct mem_cgroup_per_node *pn; |
| struct mem_cgroup *memcg; |
| |
| pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); |
| memcg = pn->memcg; |
| |
| /* |
| * The caller from rmap relies on disabled preemption because they never |
| * update their counter from in-interrupt context. For these two |
| * counters we check that the update is never performed from an |
| * interrupt context while other caller need to have disabled interrupt. |
| */ |
| __memcg_stats_lock(); |
| if (IS_ENABLED(CONFIG_DEBUG_VM)) { |
| switch (idx) { |
| case NR_ANON_MAPPED: |
| case NR_FILE_MAPPED: |
| case NR_ANON_THPS: |
| case NR_SHMEM_PMDMAPPED: |
| case NR_FILE_PMDMAPPED: |
| WARN_ON_ONCE(!in_task()); |
| break; |
| default: |
| VM_WARN_ON_IRQS_ENABLED(); |
| } |
| } |
| |
| /* Update memcg */ |
| __this_cpu_add(memcg->vmstats_percpu->state[idx], val); |
| |
| /* Update lruvec */ |
| __this_cpu_add(pn->lruvec_stats_percpu->state[idx], val); |
| |
| memcg_rstat_updated(memcg, memcg_state_val_in_pages(idx, val)); |
| memcg_stats_unlock(); |
| } |
| |
| /** |
| * __mod_lruvec_state - update lruvec memory statistics |
| * @lruvec: the lruvec |
| * @idx: the stat item |
| * @val: delta to add to the counter, can be negative |
| * |
| * The lruvec is the intersection of the NUMA node and a cgroup. This |
| * function updates the all three counters that are affected by a |
| * change of state at this level: per-node, per-cgroup, per-lruvec. |
| */ |
| void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx, |
| int val) |
| { |
| /* Update node */ |
| __mod_node_page_state(lruvec_pgdat(lruvec), idx, val); |
| |
| /* Update memcg and lruvec */ |
| if (!mem_cgroup_disabled()) |
| __mod_memcg_lruvec_state(lruvec, idx, val); |
| } |
| |
| void __lruvec_stat_mod_folio(struct folio *folio, enum node_stat_item idx, |
| int val) |
| { |
| struct mem_cgroup *memcg; |
| pg_data_t *pgdat = folio_pgdat(folio); |
| struct lruvec *lruvec; |
| |
| rcu_read_lock(); |
| memcg = folio_memcg(folio); |
| /* Untracked pages have no memcg, no lruvec. Update only the node */ |
| if (!memcg) { |
| rcu_read_unlock(); |
| __mod_node_page_state(pgdat, idx, val); |
| return; |
| } |
| |
| lruvec = mem_cgroup_lruvec(memcg, pgdat); |
| __mod_lruvec_state(lruvec, idx, val); |
| rcu_read_unlock(); |
| } |
| EXPORT_SYMBOL(__lruvec_stat_mod_folio); |
| |
| void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val) |
| { |
| pg_data_t *pgdat = page_pgdat(virt_to_page(p)); |
| struct mem_cgroup *memcg; |
| struct lruvec *lruvec; |
| |
| rcu_read_lock(); |
| memcg = mem_cgroup_from_slab_obj(p); |
| |
| /* |
| * Untracked pages have no memcg, no lruvec. Update only the |
| * node. If we reparent the slab objects to the root memcg, |
| * when we free the slab object, we need to update the per-memcg |
| * vmstats to keep it correct for the root memcg. |
| */ |
| if (!memcg) { |
| __mod_node_page_state(pgdat, idx, val); |
| } else { |
| lruvec = mem_cgroup_lruvec(memcg, pgdat); |
| __mod_lruvec_state(lruvec, idx, val); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /** |
| * __count_memcg_events - account VM events in a cgroup |
| * @memcg: the memory cgroup |
| * @idx: the event item |
| * @count: the number of events that occurred |
| */ |
| void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, |
| unsigned long count) |
| { |
| int index = memcg_events_index(idx); |
| |
| if (mem_cgroup_disabled() || index < 0) |
| return; |
| |
| memcg_stats_lock(); |
| __this_cpu_add(memcg->vmstats_percpu->events[index], count); |
| memcg_rstat_updated(memcg, count); |
| memcg_stats_unlock(); |
| } |
| |
| static unsigned long memcg_events(struct mem_cgroup *memcg, int event) |
| { |
| int index = memcg_events_index(event); |
| |
| if (index < 0) |
| return 0; |
| return READ_ONCE(memcg->vmstats->events[index]); |
| } |
| |
| static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event) |
| { |
| int index = memcg_events_index(event); |
| |
| if (index < 0) |
| return 0; |
| |
| return READ_ONCE(memcg->vmstats->events_local[index]); |
| } |
| |
| static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, |
| int nr_pages) |
| { |
| /* pagein of a big page is an event. So, ignore page size */ |
| if (nr_pages > 0) |
| __count_memcg_events(memcg, PGPGIN, 1); |
| else { |
| __count_memcg_events(memcg, PGPGOUT, 1); |
| nr_pages = -nr_pages; /* for event */ |
| } |
| |
| __this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages); |
| } |
| |
| static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, |
| enum mem_cgroup_events_target target) |
| { |
| unsigned long val, next; |
| |
| val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events); |
| next = __this_cpu_read(memcg->vmstats_percpu->targets[target]); |
| /* from time_after() in jiffies.h */ |
| if ((long)(next - val) < 0) { |
| switch (target) { |
| case MEM_CGROUP_TARGET_THRESH: |
| next = val + THRESHOLDS_EVENTS_TARGET; |
| break; |
| case MEM_CGROUP_TARGET_SOFTLIMIT: |
| next = val + SOFTLIMIT_EVENTS_TARGET; |
| break; |
| default: |
| break; |
| } |
| __this_cpu_write(memcg->vmstats_percpu->targets[target], next); |
| return true; |
| } |
| return false; |
| } |
| |
| /* |
| * Check events in order. |
| * |
| */ |
| static void memcg_check_events(struct mem_cgroup *memcg, int nid) |
| { |
| if (IS_ENABLED(CONFIG_PREEMPT_RT)) |
| return; |
| |
| /* threshold event is triggered in finer grain than soft limit */ |
| if (unlikely(mem_cgroup_event_ratelimit(memcg, |
| MEM_CGROUP_TARGET_THRESH))) { |
| bool do_softlimit; |
| |
| do_softlimit = mem_cgroup_event_ratelimit(memcg, |
| MEM_CGROUP_TARGET_SOFTLIMIT); |
| mem_cgroup_threshold(memcg); |
| if (unlikely(do_softlimit)) |
| mem_cgroup_update_tree(memcg, nid); |
| } |
| } |
| |
| struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) |
| { |
| /* |
| * mm_update_next_owner() may clear mm->owner to NULL |
| * if it races with swapoff, page migration, etc. |
| * So this can be called with p == NULL. |
| */ |
| if (unlikely(!p)) |
| return NULL; |
| |
| return mem_cgroup_from_css(task_css(p, memory_cgrp_id)); |
| } |
| EXPORT_SYMBOL(mem_cgroup_from_task); |
| |
| static __always_inline struct mem_cgroup *active_memcg(void) |
| { |
| if (!in_task()) |
| return this_cpu_read(int_active_memcg); |
| else |
| return current->active_memcg; |
| } |
| |
| /** |
| * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg. |
| * @mm: mm from which memcg should be extracted. It can be NULL. |
| * |
| * Obtain a reference on mm->memcg and returns it if successful. If mm |
| * is NULL, then the memcg is chosen as follows: |
| * 1) The active memcg, if set. |
| * 2) current->mm->memcg, if available |
| * 3) root memcg |
| * If mem_cgroup is disabled, NULL is returned. |
| */ |
| struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) |
| { |
| struct mem_cgroup *memcg; |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| /* |
| * Page cache insertions can happen without an |
| * actual mm context, e.g. during disk probing |
| * on boot, loopback IO, acct() writes etc. |
| * |
| * No need to css_get on root memcg as the reference |
| * counting is disabled on the root level in the |
| * cgroup core. See CSS_NO_REF. |
| */ |
| if (unlikely(!mm)) { |
| memcg = active_memcg(); |
| if (unlikely(memcg)) { |
| /* remote memcg must hold a ref */ |
| css_get(&memcg->css); |
| return memcg; |
| } |
| mm = current->mm; |
| if (unlikely(!mm)) |
| return root_mem_cgroup; |
| } |
| |
| rcu_read_lock(); |
| do { |
| memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); |
| if (unlikely(!memcg)) |
| memcg = root_mem_cgroup; |
| } while (!css_tryget(&memcg->css)); |
| rcu_read_unlock(); |
| return memcg; |
| } |
| EXPORT_SYMBOL(get_mem_cgroup_from_mm); |
| |
| /** |
| * get_mem_cgroup_from_current - Obtain a reference on current task's memcg. |
| */ |
| struct mem_cgroup *get_mem_cgroup_from_current(void) |
| { |
| struct mem_cgroup *memcg; |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| again: |
| rcu_read_lock(); |
| memcg = mem_cgroup_from_task(current); |
| if (!css_tryget(&memcg->css)) { |
| rcu_read_unlock(); |
| goto again; |
| } |
| rcu_read_unlock(); |
| return memcg; |
| } |
| |
| /** |
| * mem_cgroup_iter - iterate over memory cgroup hierarchy |
| * @root: hierarchy root |
| * @prev: previously returned memcg, NULL on first invocation |
| * @reclaim: cookie for shared reclaim walks, NULL for full walks |
| * |
| * Returns references to children of the hierarchy below @root, or |
| * @root itself, or %NULL after a full round-trip. |
| * |
| * Caller must pass the return value in @prev on subsequent |
| * invocations for reference counting, or use mem_cgroup_iter_break() |
| * to cancel a hierarchy walk before the round-trip is complete. |
| * |
| * Reclaimers can specify a node in @reclaim to divide up the memcgs |
| * in the hierarchy among all concurrent reclaimers operating on the |
| * same node. |
| */ |
| struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, |
| struct mem_cgroup *prev, |
| struct mem_cgroup_reclaim_cookie *reclaim) |
| { |
| struct mem_cgroup_reclaim_iter *iter; |
| struct cgroup_subsys_state *css = NULL; |
| struct mem_cgroup *memcg = NULL; |
| struct mem_cgroup *pos = NULL; |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| if (!root) |
| root = root_mem_cgroup; |
| |
| rcu_read_lock(); |
| |
| if (reclaim) { |
| struct mem_cgroup_per_node *mz; |
| |
| mz = root->nodeinfo[reclaim->pgdat->node_id]; |
| iter = &mz->iter; |
| |
| /* |
| * On start, join the current reclaim iteration cycle. |
| * Exit when a concurrent walker completes it. |
| */ |
| if (!prev) |
| reclaim->generation = iter->generation; |
| else if (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); |
| } |
| } else if (prev) { |
| pos = prev; |
| } |
| |
| 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. |
| */ |
| if (css == &root->css || css_tryget(css)) { |
| memcg = mem_cgroup_from_css(css); |
| break; |
| } |
| } |
| |
| 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++; |
| } |
| |
| out_unlock: |
| rcu_read_unlock(); |
| if (prev && prev != root) |
| css_put(&prev->css); |
| |
| return memcg; |
| } |
| |
| /** |
| * mem_cgroup_iter_break - abort a hierarchy walk prematurely |
| * @root: hierarchy root |
| * @prev: last visited hierarchy member as returned by mem_cgroup_iter() |
| */ |
| void mem_cgroup_iter_break(struct mem_cgroup *root, |
| struct mem_cgroup *prev) |
| { |
| if (!root) |
| root = root_mem_cgroup; |
| if (prev && prev != root) |
| css_put(&prev->css); |
| } |
| |
| static void __invalidate_reclaim_iterators(struct mem_cgroup *from, |
| struct mem_cgroup *dead_memcg) |
| { |
| struct mem_cgroup_reclaim_iter *iter; |
| struct mem_cgroup_per_node *mz; |
| int nid; |
| |
| for_each_node(nid) { |
| mz = from->nodeinfo[nid]; |
| iter = &mz->iter; |
| cmpxchg(&iter->position, dead_memcg, NULL); |
| } |
| } |
| |
| static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) |
| { |
| struct mem_cgroup *memcg = dead_memcg; |
| struct mem_cgroup *last; |
| |
| do { |
| __invalidate_reclaim_iterators(memcg, dead_memcg); |
| last = memcg; |
| } while ((memcg = parent_mem_cgroup(memcg))); |
| |
| /* |
| * When cgroup1 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 (!mem_cgroup_is_root(last)) |
| __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. Otherwise, it will iterate |
| * over all tasks and return 0. |
| * |
| * This function must not be called for the root memory cgroup. |
| */ |
| void 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(mem_cgroup_is_root(memcg)); |
| |
| for_each_mem_cgroup_tree(iter, memcg) { |
| struct css_task_iter it; |
| struct task_struct *task; |
| |
| css_task_iter_start(&iter->css, CSS_TASK_ITER_PROCS, &it); |
| while (!ret && (task = css_task_iter_next(&it))) |
| ret = fn(task, arg); |
| css_task_iter_end(&it); |
| if (ret) { |
| mem_cgroup_iter_break(memcg, iter); |
| break; |
| } |
| } |
| } |
| |
| #ifdef CONFIG_DEBUG_VM |
| void lruvec_memcg_debug(struct lruvec *lruvec, struct folio *folio) |
| { |
| struct mem_cgroup *memcg; |
| |
| if (mem_cgroup_disabled()) |
| return; |
| |
| memcg = folio_memcg(folio); |
| |
| if (!memcg) |
| VM_BUG_ON_FOLIO(!mem_cgroup_is_root(lruvec_memcg(lruvec)), folio); |
| else |
| VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != memcg, folio); |
| } |
| #endif |
| |
| /** |
| * folio_lruvec_lock - Lock the lruvec for a folio. |
| * @folio: Pointer to the folio. |
| * |
| * These functions are safe to use under any of the following conditions: |
| * - folio locked |
| * - folio_test_lru false |
| * - folio_memcg_lock() |
| * - folio frozen (refcount of 0) |
| * |
| * Return: The lruvec this folio is on with its lock held. |
| */ |
| struct lruvec *folio_lruvec_lock(struct folio *folio) |
| { |
| struct lruvec *lruvec = folio_lruvec(folio); |
| |
| spin_lock(&lruvec->lru_lock); |
| lruvec_memcg_debug(lruvec, folio); |
| |
| return lruvec; |
| } |
| |
| /** |
| * folio_lruvec_lock_irq - Lock the lruvec for a folio. |
| * @folio: Pointer to the folio. |
| * |
| * These functions are safe to use under any of the following conditions: |
| * - folio locked |
| * - folio_test_lru false |
| * - folio_memcg_lock() |
| * - folio frozen (refcount of 0) |
| * |
| * Return: The lruvec this folio is on with its lock held and interrupts |
| * disabled. |
| */ |
| struct lruvec *folio_lruvec_lock_irq(struct folio *folio) |
| { |
| struct lruvec *lruvec = folio_lruvec(folio); |
| |
| spin_lock_irq(&lruvec->lru_lock); |
| lruvec_memcg_debug(lruvec, folio); |
| |
| return lruvec; |
| } |
| |
| /** |
| * folio_lruvec_lock_irqsave - Lock the lruvec for a folio. |
| * @folio: Pointer to the folio. |
| * @flags: Pointer to irqsave flags. |
| * |
| * These functions are safe to use under any of the following conditions: |
| * - folio locked |
| * - folio_test_lru false |
| * - folio_memcg_lock() |
| * - folio frozen (refcount of 0) |
| * |
| * Return: The lruvec this folio is on with its lock held and interrupts |
| * disabled. |
| */ |
| struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio, |
| unsigned long *flags) |
| { |
| struct lruvec *lruvec = folio_lruvec(folio); |
| |
| spin_lock_irqsave(&lruvec->lru_lock, *flags); |
| lruvec_memcg_debug(lruvec, folio); |
| |
| return lruvec; |
| } |
| |
| /** |
| * mem_cgroup_update_lru_size - account for adding or removing an lru page |
| * @lruvec: mem_cgroup per zone lru vector |
| * @lru: index of lru list the page is sitting on |
| * @zid: zone id of the accounted pages |
| * @nr_pages: positive when adding or negative when removing |
| * |
| * This function must be called under lru_lock, just before a page is added |
| * to or just after a page is removed from an lru list. |
| */ |
| void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, |
| int zid, int nr_pages) |
| { |
| struct mem_cgroup_per_node *mz; |
| unsigned long *lru_size; |
| long size; |
| |
| if (mem_cgroup_disabled()) |
| return; |
| |
| mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec); |
| lru_size = &mz->lru_zone_size[zid][lru]; |
| |
| if (nr_pages < 0) |
| *lru_size += nr_pages; |
| |
| size = *lru_size; |
| if (WARN_ONCE(size < 0, |
| "%s(%p, %d, %d): lru_size %ld\n", |
| __func__, lruvec, lru, nr_pages, size)) { |
| VM_BUG_ON(1); |
| *lru_size = 0; |
| } |
| |
| if (nr_pages > 0) |
| *lru_size += nr_pages; |
| } |
| |
| /** |
| * mem_cgroup_margin - calculate chargeable space of a memory cgroup |
| * @memcg: the memory cgroup |
| * |
| * Returns the maximum amount of memory @mem can be charged with, in |
| * pages. |
| */ |
| static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg) |
| { |
| unsigned long margin = 0; |
| unsigned long count; |
| unsigned long limit; |
| |
| count = page_counter_read(&memcg->memory); |
| limit = READ_ONCE(memcg->memory.max); |
| if (count < limit) |
| margin = limit - count; |
| |
| if (do_memsw_account()) { |
| count = page_counter_read(&memcg->memsw); |
| limit = READ_ONCE(memcg->memsw.max); |
| if (count < limit) |
| margin = min(margin, limit - count); |
| else |
| margin = 0; |
| } |
| |
| return margin; |
| } |
| |
| /* |
| * A routine for checking "mem" is under move_account() or not. |
| * |
| * Checking a cgroup is mc.from or mc.to or under hierarchy of |
| * moving cgroups. This is for waiting at high-memory pressure |
| * caused by "move". |
| */ |
| static bool mem_cgroup_under_move(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *from; |
| struct mem_cgroup *to; |
| bool ret = false; |
| /* |
| * Unlike task_move routines, we access mc.to, mc.from not under |
| * mutual exclusion by cgroup_mutex. Here, we take spinlock instead. |
| */ |
| spin_lock(&mc.lock); |
| from = mc.from; |
| to = mc.to; |
| if (!from) |
| goto unlock; |
| |
| ret = mem_cgroup_is_descendant(from, memcg) || |
| mem_cgroup_is_descendant(to, memcg); |
| unlock: |
| spin_unlock(&mc.lock); |
| return ret; |
| } |
| |
| static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg) |
| { |
| if (mc.moving_task && current != mc.moving_task) { |
| if (mem_cgroup_under_move(memcg)) { |
| DEFINE_WAIT(wait); |
| prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE); |
| /* moving charge context might have finished. */ |
| if (mc.moving_task) |
| schedule(); |
| finish_wait(&mc.waitq, &wait); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| struct memory_stat { |
| const char *name; |
| unsigned int idx; |
| }; |
| |
| static const struct memory_stat memory_stats[] = { |
| { "anon", NR_ANON_MAPPED }, |
| { "file", NR_FILE_PAGES }, |
| { "kernel", MEMCG_KMEM }, |
| { "kernel_stack", NR_KERNEL_STACK_KB }, |
| { "pagetables", NR_PAGETABLE }, |
| { "sec_pagetables", NR_SECONDARY_PAGETABLE }, |
| { "percpu", MEMCG_PERCPU_B }, |
| { "sock", MEMCG_SOCK }, |
| { "vmalloc", MEMCG_VMALLOC }, |
| { "shmem", NR_SHMEM }, |
| #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP) |
| { "zswap", MEMCG_ZSWAP_B }, |
| { "zswapped", MEMCG_ZSWAPPED }, |
| #endif |
| { "file_mapped", NR_FILE_MAPPED }, |
| { "file_dirty", NR_FILE_DIRTY }, |
| { "file_writeback", NR_WRITEBACK }, |
| #ifdef CONFIG_SWAP |
| { "swapcached", NR_SWAPCACHE }, |
| #endif |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| { "anon_thp", NR_ANON_THPS }, |
| { "file_thp", NR_FILE_THPS }, |
| { "shmem_thp", NR_SHMEM_THPS }, |
| #endif |
| { "inactive_anon", NR_INACTIVE_ANON }, |
| { "active_anon", NR_ACTIVE_ANON }, |
| { "inactive_file", NR_INACTIVE_FILE }, |
| { "active_file", NR_ACTIVE_FILE }, |
| { "unevictable", NR_UNEVICTABLE }, |
| { "slab_reclaimable", NR_SLAB_RECLAIMABLE_B }, |
| { "slab_unreclaimable", NR_SLAB_UNRECLAIMABLE_B }, |
| |
| /* The memory events */ |
| { "workingset_refault_anon", WORKINGSET_REFAULT_ANON }, |
| { "workingset_refault_file", WORKINGSET_REFAULT_FILE }, |
| { "workingset_activate_anon", WORKINGSET_ACTIVATE_ANON }, |
| { "workingset_activate_file", WORKINGSET_ACTIVATE_FILE }, |
| { "workingset_restore_anon", WORKINGSET_RESTORE_ANON }, |
| { "workingset_restore_file", WORKINGSET_RESTORE_FILE }, |
| { "workingset_nodereclaim", WORKINGSET_NODERECLAIM }, |
| }; |
| |
| /* The actual unit of the state item, not the same as the output unit */ |
| static int memcg_page_state_unit(int item) |
| { |
| switch (item) { |
| case MEMCG_PERCPU_B: |
| case MEMCG_ZSWAP_B: |
| case NR_SLAB_RECLAIMABLE_B: |
| case NR_SLAB_UNRECLAIMABLE_B: |
| return 1; |
| case NR_KERNEL_STACK_KB: |
| return SZ_1K; |
| default: |
| return PAGE_SIZE; |
| } |
| } |
| |
| /* Translate stat items to the correct unit for memory.stat output */ |
| static int memcg_page_state_output_unit(int item) |
| { |
| /* |
| * Workingset state is actually in pages, but we export it to userspace |
| * as a scalar count of events, so special case it here. |
| */ |
| switch (item) { |
| case WORKINGSET_REFAULT_ANON: |
| case WORKINGSET_REFAULT_FILE: |
| case WORKINGSET_ACTIVATE_ANON: |
| case WORKINGSET_ACTIVATE_FILE: |
| case WORKINGSET_RESTORE_ANON: |
| case WORKINGSET_RESTORE_FILE: |
| case WORKINGSET_NODERECLAIM: |
| return 1; |
| default: |
| return memcg_page_state_unit(item); |
| } |
| } |
| |
| static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg, |
| int item) |
| { |
| return memcg_page_state(memcg, item) * |
| memcg_page_state_output_unit(item); |
| } |
| |
| static inline unsigned long memcg_page_state_local_output( |
| struct mem_cgroup *memcg, int item) |
| { |
| return memcg_page_state_local(memcg, item) * |
| memcg_page_state_output_unit(item); |
| } |
| |
| static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) |
| { |
| 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: |
| */ |
| mem_cgroup_flush_stats(memcg); |
| |
| for (i = 0; i < ARRAY_SIZE(memory_stats); i++) { |
| u64 size; |
| |
| size = memcg_page_state_output(memcg, memory_stats[i].idx); |
| seq_buf_printf(s, "%s %llu\n", memory_stats[i].name, size); |
| |
| if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) { |
| size += memcg_page_state_output(memcg, |
| NR_SLAB_RECLAIMABLE_B); |
| seq_buf_printf(s, "slab %llu\n", size); |
| } |
| } |
| |
| /* Accumulated memory events */ |
| seq_buf_printf(s, "pgscan %lu\n", |
| memcg_events(memcg, PGSCAN_KSWAPD) + |
| memcg_events(memcg, PGSCAN_DIRECT) + |
| memcg_events(memcg, PGSCAN_KHUGEPAGED)); |
| seq_buf_printf(s, "pgsteal %lu\n", |
| memcg_events(memcg, PGSTEAL_KSWAPD) + |
| memcg_events(memcg, PGSTEAL_DIRECT) + |
| memcg_events(memcg, PGSTEAL_KHUGEPAGED)); |
| |
| for (i = 0; i < ARRAY_SIZE(memcg_vm_event_stat); i++) { |
| if (memcg_vm_event_stat[i] == PGPGIN || |
| memcg_vm_event_stat[i] == PGPGOUT) |
| continue; |
| |
| seq_buf_printf(s, "%s %lu\n", |
| vm_event_name(memcg_vm_event_stat[i]), |
| memcg_events(memcg, memcg_vm_event_stat[i])); |
| } |
| |
| /* The above should easily fit into one page */ |
| WARN_ON_ONCE(seq_buf_has_overflowed(s)); |
| } |
| |
| static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s); |
| |
| static void memory_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) |
| { |
| if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) |
| memcg_stat_format(memcg, s); |
| else |
| memcg1_stat_format(memcg, s); |
| WARN_ON_ONCE(seq_buf_has_overflowed(s)); |
| } |
| |
| /** |
| * mem_cgroup_print_oom_context: Print OOM information relevant to |
| * memory controller. |
| * @memcg: The memory cgroup that went over limit |
| * @p: Task that is going to be killed |
| * |
| * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is |
| * enabled |
| */ |
| void mem_cgroup_print_oom_context(struct mem_cgroup *memcg, struct task_struct *p) |
| { |
| rcu_read_lock(); |
| |
| if (memcg) { |
| pr_cont(",oom_memcg="); |
| pr_cont_cgroup_path(memcg->css.cgroup); |
| } else |
| pr_cont(",global_oom"); |
| if (p) { |
| pr_cont(",task_memcg="); |
| pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id)); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /** |
| * mem_cgroup_print_oom_meminfo: Print OOM memory information relevant to |
| * memory controller. |
| * @memcg: The memory cgroup that went over limit |
| */ |
| void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) |
| { |
| /* Use static buffer, for the caller is holding oom_lock. */ |
| static char buf[PAGE_SIZE]; |
| struct seq_buf s; |
| |
| lockdep_assert_held(&oom_lock); |
| |
| pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n", |
| K((u64)page_counter_read(&memcg->memory)), |
| K((u64)READ_ONCE(memcg->memory.max)), memcg->memory.failcnt); |
| if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) |
| pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n", |
| K((u64)page_counter_read(&memcg->swap)), |
| K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt); |
| else { |
| pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n", |
| K((u64)page_counter_read(&memcg->memsw)), |
| K((u64)memcg->memsw.max), memcg->memsw.failcnt); |
| pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n", |
| K((u64)page_counter_read(&memcg->kmem)), |
| K((u64)memcg->kmem.max), memcg->kmem.failcnt); |
| } |
| |
| pr_info("Memory cgroup stats for "); |
| pr_cont_cgroup_path(memcg->css.cgroup); |
| pr_cont(":"); |
| seq_buf_init(&s, buf, sizeof(buf)); |
| memory_stat_format(memcg, &s); |
| seq_buf_do_printk(&s, KERN_INFO); |
| } |
| |
| /* |
| * Return the memory (and swap, if configured) limit for a memcg. |
| */ |
| unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) |
| { |
| unsigned long max = READ_ONCE(memcg->memory.max); |
| |
| if (do_memsw_account()) { |
| if (mem_cgroup_swappiness(memcg)) { |
| /* Calculate swap excess capacity from memsw limit */ |
| unsigned long swap = READ_ONCE(memcg->memsw.max) - max; |
| |
| max += min(swap, (unsigned long)total_swap_pages); |
| } |
| } else { |
| if (mem_cgroup_swappiness(memcg)) |
| max += min(READ_ONCE(memcg->swap.max), |
| (unsigned long)total_swap_pages); |
| } |
| return max; |
| } |
| |
| unsigned long mem_cgroup_size(struct mem_cgroup *memcg) |
| { |
| return page_counter_read(&memcg->memory); |
| } |
| |
| static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, |
| int order) |
| { |
| struct oom_control oc = { |
| .zonelist = NULL, |
| .nodemask = NULL, |
| .memcg = memcg, |
| .gfp_mask = gfp_mask, |
| .order = order, |
| }; |
| bool ret = true; |
| |
| if (mutex_lock_killable(&oom_lock)) |
| return true; |
| |
| if (mem_cgroup_margin(memcg) >= (1 << order)) |
| goto unlock; |
| |
| /* |
| * A few threads which were not waiting at mutex_lock_killable() can |
| * fail to bail out. Therefore, check again after holding oom_lock. |
| */ |
| ret = task_is_dying() || out_of_memory(&oc); |
| |
| unlock: |
| mutex_unlock(&oom_lock); |
| return ret; |
| } |
| |
| static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, |
| pg_data_t *pgdat, |
| gfp_t gfp_mask, |
| unsigned long *total_scanned) |
| { |
| struct mem_cgroup *victim = NULL; |
| int total = 0; |
| int loop = 0; |
| unsigned long excess; |
| unsigned long nr_scanned; |
| struct mem_cgroup_reclaim_cookie reclaim = { |
| .pgdat = pgdat, |
| }; |
| |
| excess = soft_limit_excess(root_memcg); |
| |
| while (1) { |
| victim = mem_cgroup_iter(root_memcg, victim, &reclaim); |
| if (!victim) { |
| loop++; |
| if (loop >= 2) { |
| /* |
| * If we have not been able to reclaim |
| * anything, it might because there are |
| * no reclaimable pages under this hierarchy |
| */ |
| if (!total) |
| break; |
| /* |
| * We want to do more targeted reclaim. |
| * excess >> 2 is not to excessive so as to |
| * reclaim too much, nor too less that we keep |
| * coming back to reclaim from this cgroup |
| */ |
| if (total >= (excess >> 2) || |
| (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) |
| break; |
| } |
| continue; |
| } |
| total += mem_cgroup_shrink_node(victim, gfp_mask, false, |
| pgdat, &nr_scanned); |
| *total_scanned += nr_scanned; |
| if (!soft_limit_excess(root_memcg)) |
| break; |
| } |
| mem_cgroup_iter_break(root_memcg, victim); |
| return total; |
| } |
| |
| #ifdef CONFIG_LOCKDEP |
| static struct lockdep_map memcg_oom_lock_dep_map = { |
| .name = "memcg_oom_lock", |
| }; |
| #endif |
| |
| static DEFINE_SPINLOCK(memcg_oom_lock); |
| |
| /* |
| * Check OOM-Killer is already running under our hierarchy. |
| * If someone is running, return false. |
| */ |
| static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *iter, *failed = NULL; |
| |
| spin_lock(&memcg_oom_lock); |
| |
| for_each_mem_cgroup_tree(iter, memcg) { |
| if (iter->oom_lock) { |
| /* |
| * this subtree of our hierarchy is already locked |
| * so we cannot give a lock. |
| */ |
| failed = iter; |
| mem_cgroup_iter_break(memcg, iter); |
| break; |
| } else |
| iter->oom_lock = true; |
| } |
| |
| if (failed) { |
| /* |
| * OK, we failed to lock the whole subtree so we have |
| * to clean up what we set up to the failing subtree |
| */ |
| for_each_mem_cgroup_tree(iter, memcg) { |
| if (iter == failed) { |
| mem_cgroup_iter_break(memcg, iter); |
| break; |
| } |
| iter->oom_lock = false; |
| } |
| } else |
| mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_); |
| |
| spin_unlock(&memcg_oom_lock); |
| |
| return !failed; |
| } |
| |
| static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *iter; |
| |
| spin_lock(&memcg_oom_lock); |
| mutex_release(&memcg_oom_lock_dep_map, _RET_IP_); |
| for_each_mem_cgroup_tree(iter, memcg) |
| iter->oom_lock = false; |
| spin_unlock(&memcg_oom_lock); |
| } |
| |
| static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *iter; |
| |
| spin_lock(&memcg_oom_lock); |
| for_each_mem_cgroup_tree(iter, memcg) |
| iter->under_oom++; |
| spin_unlock(&memcg_oom_lock); |
| } |
| |
| static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *iter; |
| |
| /* |
| * Be careful about under_oom underflows because a child memcg |
| * could have been added after mem_cgroup_mark_under_oom. |
| */ |
| spin_lock(&memcg_oom_lock); |
| for_each_mem_cgroup_tree(iter, memcg) |
| if (iter->under_oom > 0) |
| iter->under_oom--; |
| spin_unlock(&memcg_oom_lock); |
| } |
| |
| static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); |
| |
| struct oom_wait_info { |
| struct mem_cgroup *memcg; |
| wait_queue_entry_t wait; |
| }; |
| |
| static int memcg_oom_wake_function(wait_queue_entry_t *wait, |
| unsigned mode, int sync, void *arg) |
| { |
| struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg; |
| struct mem_cgroup *oom_wait_memcg; |
| struct oom_wait_info *oom_wait_info; |
| |
| oom_wait_info = container_of(wait, struct oom_wait_info, wait); |
| oom_wait_memcg = oom_wait_info->memcg; |
| |
| if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) && |
| !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg)) |
| return 0; |
| return autoremove_wake_function(wait, mode, sync, arg); |
| } |
| |
| static void memcg_oom_recover(struct mem_cgroup *memcg) |
| { |
| /* |
| * For the following lockless ->under_oom test, the only required |
| * guarantee is that it must see the state asserted by an OOM when |
| * this function is called as a result of userland actions |
| * triggered by the notification of the OOM. This is trivially |
| * achieved by invoking mem_cgroup_mark_under_oom() before |
| * triggering notification. |
| */ |
| if (memcg && memcg->under_oom) |
| __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); |
| } |
| |
| /* |
| * Returns true if successfully killed one or more processes. Though in some |
| * corner cases it can return true even without killing any process. |
| */ |
| static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) |
| { |
| bool locked, ret; |
| |
| if (order > PAGE_ALLOC_COSTLY_ORDER) |
| return false; |
| |
| memcg_memory_event(memcg, MEMCG_OOM); |
| |
| /* |
| * We are in the middle of the charge context here, so we |
| * don't want to block when potentially sitting on a callstack |
| * that holds all kinds of filesystem and mm locks. |
| * |
| * cgroup1 allows disabling the OOM killer and waiting for outside |
| * handling until the charge can succeed; remember the context and put |
| * the task to sleep at the end of the page fault when all locks are |
| * released. |
| * |
| * On the other hand, in-kernel OOM killer allows for an async victim |
| * memory reclaim (oom_reaper) and that means that we are not solely |
| * relying on the oom victim to make a forward progress and we can |
| * invoke the oom killer here. |
| * |
| * Please note that mem_cgroup_out_of_memory might fail to find a |
| * victim and then we have to bail out from the charge path. |
| */ |
| if (READ_ONCE(memcg->oom_kill_disable)) { |
| if (current->in_user_fault) { |
| css_get(&memcg->css); |
| current->memcg_in_oom = memcg; |
| current->memcg_oom_gfp_mask = mask; |
| current->memcg_oom_order = order; |
| } |
| return false; |
| } |
| |
| 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); |
| ret = mem_cgroup_out_of_memory(memcg, mask, order); |
| |
| 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); |
| |
| schedule(); |
| mem_cgroup_unmark_under_oom(memcg); |
| finish_wait(&memcg_oom_waitq, &owait.wait); |
| |
| if (locked) |
| mem_cgroup_oom_unlock(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 (mem_cgroup_is_root(memcg)) |
| goto out; |
| |
| /* |
| * If the victim task has been asynchronously moved to a different |
| * memory cgroup, we might end up killing tasks outside oom_domain. |
| * In this case it's better to ignore memory.group.oom. |
| */ |
| if (unlikely(!mem_cgroup_is_descendant(memcg, oom_domain))) |
| goto out; |
| |
| /* |
| * Traverse the memory cgroup hierarchy from the victim task's |
| * cgroup up to the OOMing cgroup (or root) to find the |
| * highest-level memory cgroup with oom.group set. |
| */ |
| for (; memcg; memcg = parent_mem_cgroup(memcg)) { |
| if (READ_ONCE(memcg->oom_group)) |
| oom_group = memcg; |
| |
| if (memcg == oom_domain) |
| break; |
| } |
| |
| if (oom_group) |
| css_get(&oom_group->css); |
| out: |
| rcu_read_unlock(); |
| |
| return oom_group; |
| } |
| |
| void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) |
| { |
| pr_info("Tasks in "); |
| pr_cont_cgroup_path(memcg->css.cgroup); |
| pr_cont(" are going to be killed due to memory.oom.group set\n"); |
| } |
| |
| /** |
| * folio_memcg_lock - Bind a folio to its memcg. |
| * @folio: The folio. |
| * |
| * This function prevents unlocked LRU folios from being moved to |
| * another cgroup. |
| * |
| * It ensures lifetime of the bound memcg. The caller is responsible |
| * for the lifetime of the folio. |
| */ |
| void folio_memcg_lock(struct folio *folio) |
| { |
| struct mem_cgroup *memcg; |
| unsigned long flags; |
| |
| /* |
| * The RCU lock is held throughout the transaction. The fast |
| * path can get away without acquiring the memcg->move_lock |
| * because page moving starts with an RCU grace period. |
| */ |
| rcu_read_lock(); |
| |
| if (mem_cgroup_disabled()) |
| return; |
| again: |
| memcg = folio_memcg(folio); |
| if (unlikely(!memcg)) |
| return; |
| |
| #ifdef CONFIG_PROVE_LOCKING |
| local_irq_save(flags); |
| might_lock(&memcg->move_lock); |
| local_irq_restore(flags); |
| #endif |
| |
| if (atomic_read(&memcg->moving_account) <= 0) |
| return; |
| |
| spin_lock_irqsave(&memcg->move_lock, flags); |
| if (memcg != folio_memcg(folio)) { |
| spin_unlock_irqrestore(&memcg->move_lock, flags); |
| goto again; |
| } |
| |
| /* |
| * When charge migration first begins, we can have multiple |
| * critical sections holding the fast-path RCU lock and one |
| * holding the slowpath move_lock. Track the task who has the |
| * move_lock for folio_memcg_unlock(). |
| */ |
| memcg->move_lock_task = current; |
| memcg->move_lock_flags = flags; |
| } |
| |
| static void __folio_memcg_unlock(struct mem_cgroup *memcg) |
| { |
| if (memcg && memcg->move_lock_task == current) { |
| unsigned long flags = memcg->move_lock_flags; |
| |
| memcg->move_lock_task = NULL; |
| memcg->move_lock_flags = 0; |
| |
| spin_unlock_irqrestore(&memcg->move_lock, flags); |
| } |
| |
| rcu_read_unlock(); |
| } |
| |
| /** |
| * folio_memcg_unlock - Release the binding between a folio and its memcg. |
| * @folio: The folio. |
| * |
| * This releases the binding created by folio_memcg_lock(). This does |
| * not change the accounting of this folio to its memcg, but it does |
| * permit others to change it. |
| */ |
| void folio_memcg_unlock(struct folio *folio) |
| { |
| __folio_memcg_unlock(folio_memcg(folio)); |
| } |
| |
| struct memcg_stock_pcp { |
| local_lock_t stock_lock; |
| struct mem_cgroup *cached; /* this never be root cgroup */ |
| unsigned int nr_pages; |
| |
| #ifdef CONFIG_MEMCG_KMEM |
| struct obj_cgroup *cached_objcg; |
| struct pglist_data *cached_pgdat; |
| unsigned int nr_bytes; |
| int nr_slab_reclaimable_b; |
| int nr_slab_unreclaimable_b; |
| #endif |
| |
| struct work_struct work; |
| unsigned long flags; |
| #define FLUSHING_CACHED_CHARGE 0 |
| }; |
| static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { |
| .stock_lock = INIT_LOCAL_LOCK(stock_lock), |
| }; |
| static DEFINE_MUTEX(percpu_charge_mutex); |
| |
| #ifdef CONFIG_MEMCG_KMEM |
| static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock); |
| static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, |
| struct mem_cgroup *root_memcg); |
| static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages); |
| |
| #else |
| static inline struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) |
| { |
| return NULL; |
| } |
| static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, |
| struct mem_cgroup *root_memcg) |
| { |
| return false; |
| } |
| static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages) |
| { |
| } |
| #endif |
| |
| /** |
| * consume_stock: Try to consume stocked charge on this cpu. |
| * @memcg: memcg to consume from. |
| * @nr_pages: how many pages to charge. |
| * |
| * The charges will only happen if @memcg matches the current cpu's memcg |
| * stock, and at least @nr_pages are available in that stock. Failure to |
| * service an allocation will refill the stock. |
| * |
| * returns true if successful, false otherwise. |
| */ |
| static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) |
| { |
| struct memcg_stock_pcp *stock; |
| unsigned long flags; |
| bool ret = false; |
| |
| if (nr_pages > MEMCG_CHARGE_BATCH) |
| return ret; |
| |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| |
| stock = this_cpu_ptr(&memcg_stock); |
| if (memcg == READ_ONCE(stock->cached) && stock->nr_pages >= nr_pages) { |
| stock->nr_pages -= nr_pages; |
| ret = true; |
| } |
| |
| local_unlock_irqrestore(&memcg_stock.stock_lock, 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 = READ_ONCE(stock->cached); |
| |
| if (!old) |
| return; |
| |
| if (stock->nr_pages) { |
| page_counter_uncharge(&old->memory, stock->nr_pages); |
| if (do_memsw_account()) |
| page_counter_uncharge(&old->memsw, stock->nr_pages); |
| stock->nr_pages = 0; |
| } |
| |
| css_put(&old->css); |
| WRITE_ONCE(stock->cached, NULL); |
| } |
| |
| static void drain_local_stock(struct work_struct *dummy) |
| { |
| struct memcg_stock_pcp *stock; |
| struct obj_cgroup *old = NULL; |
| unsigned long flags; |
| |
| /* |
| * The only protection from cpu hotplug (memcg_hotplug_cpu_dead) vs. |
| * drain_stock races is that we always operate on local CPU stock |
| * here with IRQ disabled |
| */ |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| |
| stock = this_cpu_ptr(&memcg_stock); |
| old = drain_obj_stock(stock); |
| drain_stock(stock); |
| clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); |
| |
| local_unlock_irqrestore(&memcg_stock.stock_lock, flags); |
| if (old) |
| obj_cgroup_put(old); |
| } |
| |
| /* |
| * 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; |
| |
| stock = this_cpu_ptr(&memcg_stock); |
| if (READ_ONCE(stock->cached) != memcg) { /* reset if necessary */ |
| drain_stock(stock); |
| css_get(&memcg->css); |
| WRITE_ONCE(stock->cached, memcg); |
| } |
| stock->nr_pages += nr_pages; |
| |
| if (stock->nr_pages > MEMCG_CHARGE_BATCH) |
| drain_stock(stock); |
| } |
| |
| static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) |
| { |
| unsigned long flags; |
| |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| __refill_stock(memcg, nr_pages); |
| local_unlock_irqrestore(&memcg_stock.stock_lock, 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. |
| */ |
| migrate_disable(); |
| curcpu = smp_processor_id(); |
| for_each_online_cpu(cpu) { |
| struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); |
| struct mem_cgroup *memcg; |
| bool flush = false; |
| |
| rcu_read_lock(); |
| memcg = READ_ONCE(stock->cached); |
| if (memcg && stock->nr_pages && |
| mem_cgroup_is_descendant(memcg, root_memcg)) |
| flush = true; |
| else if (obj_stock_flush_required(stock, root_memcg)) |
| flush = true; |
| rcu_read_unlock(); |
| |
| if (flush && |
| !test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) { |
| if (cpu == curcpu) |
| drain_local_stock(&stock->work); |
| else if (!cpu_is_isolated(cpu)) |
| schedule_work_on(cpu, &stock->work); |
| } |
| } |
| migrate_enable(); |
| mutex_unlock(&percpu_charge_mutex); |
| } |
| |
| static int memcg_hotplug_cpu_dead(unsigned int cpu) |
| { |
| struct memcg_stock_pcp *stock; |
| |
| stock = &per_cpu(memcg_stock, cpu); |
| drain_stock(stock); |
| |
| return 0; |
| } |
| |
| static unsigned long reclaim_high(struct mem_cgroup *memcg, |
| unsigned int nr_pages, |
| gfp_t gfp_mask) |
| { |
| unsigned long nr_reclaimed = 0; |
| |
| do { |
| unsigned long pflags; |
| |
| if (page_counter_read(&memcg->memory) <= |
| READ_ONCE(memcg->memory.high)) |
| continue; |
| |
| memcg_memory_event(memcg, MEMCG_HIGH); |
| |
| psi_memstall_enter(&pflags); |
| nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages, |
| gfp_mask, |
| MEMCG_RECLAIM_MAY_SWAP); |
| psi_memstall_leave(&pflags); |
| } while ((memcg = parent_mem_cgroup(memcg)) && |
| !mem_cgroup_is_root(memcg)); |
| |
| return nr_reclaimed; |
| } |
| |
| static void high_work_func(struct work_struct *work) |
| { |
| struct mem_cgroup *memcg; |
| |
| memcg = container_of(work, struct mem_cgroup, high_work); |
| reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL); |
| } |
| |
| /* |
| * Clamp the maximum sleep time per allocation batch to 2 seconds. This is |
| * enough to still cause a significant slowdown in most cases, while still |
| * allowing diagnostics and tracing to proceed without becoming stuck. |
| */ |
| #define MEMCG_MAX_HIGH_DELAY_JIFFIES (2UL*HZ) |
| |
| /* |
| * When calculating the delay, we use these either side of the exponentiation to |
| * maintain precision and scale to a reasonable number of jiffies (see the table |
| * below. |
| * |
| * - MEMCG_DELAY_PRECISION_SHIFT: Extra precision bits while translating the |
| * overage ratio to a delay. |
| * - MEMCG_DELAY_SCALING_SHIFT: The number of bits to scale down the |
| * proposed penalty in order to reduce to a reasonable number of jiffies, and |
| * to produce a reasonable delay curve. |
| * |
| * MEMCG_DELAY_SCALING_SHIFT just happens to be a number that produces a |
| * reasonable delay curve compared to precision-adjusted overage, not |
| * penalising heavily at first, but still making sure that growth beyond the |
| * limit penalises misbehaviour cgroups by slowing them down exponentially. For |
| * example, with a high of 100 megabytes: |
| * |
| * +-------+------------------------+ |
| * | usage | time to allocate in ms | |
| * +-------+------------------------+ |
| * | 100M | 0 | |
| * | 101M | 6 | |
| * | 102M | 25 | |
| * | 103M | 57 | |
| * | 104M | 102 | |
| * | 105M | 159 | |
| * | 106M | 230 | |
| * | 107M | 313 | |
| * | 108M | 409 | |
| * | 109M | 518 | |
| * | 110M | 639 | |
| * | 111M | 774 | |
| * | 112M | 921 | |
| * | 113M | 1081 | |
| * | 114M | 1254 | |
| * | 115M | 1439 | |
| * | 116M | 1638 | |
| * | 117M | 1849 | |
| * | 118M | 2000 | |
| * | 119M | 2000 | |
| * | 120M | 2000 | |
| * +-------+------------------------+ |
| */ |
| #define MEMCG_DELAY_PRECISION_SHIFT 20 |
| #define MEMCG_DELAY_SCALING_SHIFT 14 |
| |
| static u64 calculate_overage(unsigned long usage, unsigned long high) |
| { |
| u64 overage; |
| |
| if (usage <= high) |
| return 0; |
| |
| /* |
| * Prevent division by 0 in overage calculation by acting as if |
| * it was a threshold of 1 page |
| */ |
| high = max(high, 1UL); |
| |
| overage = usage - high; |
| overage <<= MEMCG_DELAY_PRECISION_SHIFT; |
| return div64_u64(overage, high); |
| } |
| |
| static u64 mem_find_max_overage(struct mem_cgroup *memcg) |
| { |
| u64 overage, max_overage = 0; |
| |
| do { |
| overage = calculate_overage(page_counter_read(&memcg->memory), |
| READ_ONCE(memcg->memory.high)); |
| max_overage = max(overage, max_overage); |
| } while ((memcg = parent_mem_cgroup(memcg)) && |
| !mem_cgroup_is_root(memcg)); |
| |
| return max_overage; |
| } |
| |
| static u64 swap_find_max_overage(struct mem_cgroup *memcg) |
| { |
| u64 overage, max_overage = 0; |
| |
| do { |
| overage = calculate_overage(page_counter_read(&memcg->swap), |
| READ_ONCE(memcg->swap.high)); |
| if (overage) |
| memcg_memory_event(memcg, MEMCG_SWAP_HIGH); |
| max_overage = max(overage, max_overage); |
| } while ((memcg = parent_mem_cgroup(memcg)) && |
| !mem_cgroup_is_root(memcg)); |
| |
| return max_overage; |
| } |
| |
| /* |
| * Get the number of jiffies that we should penalise a mischievous cgroup which |
| * is exceeding its memory.high by checking both it and its ancestors. |
| */ |
| static unsigned long calculate_high_delay(struct mem_cgroup *memcg, |
| unsigned int nr_pages, |
| u64 max_overage) |
| { |
| unsigned long penalty_jiffies; |
| |
| if (!max_overage) |
| return 0; |
| |
| /* |
| * We use overage compared to memory.high to calculate the number of |
| * jiffies to sleep (penalty_jiffies). Ideally this value should be |
| * fairly lenient on small overages, and increasingly harsh when the |
| * memcg in question makes it clear that it has no intention of stopping |
| * its crazy behaviour, so we exponentially increase the delay based on |
| * overage amount. |
| */ |
| penalty_jiffies = max_overage * max_overage * HZ; |
| penalty_jiffies >>= MEMCG_DELAY_PRECISION_SHIFT; |
| penalty_jiffies >>= MEMCG_DELAY_SCALING_SHIFT; |
| |
| /* |
| * Factor in the task's own contribution to the overage, such that four |
| * N-sized allocations are throttled approximately the same as one |
| * 4N-sized allocation. |
| * |
| * MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or |
| * larger the current charge patch is than that. |
| */ |
| return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH; |
| } |
| |
| /* |
| * Reclaims memory over the high limit. Called directly from |
| * try_charge() (context permitting), as well as from the userland |
| * return path where reclaim is always able to block. |
| */ |
| void mem_cgroup_handle_over_high(gfp_t gfp_mask) |
| { |
| unsigned long penalty_jiffies; |
| unsigned long pflags; |
| unsigned long nr_reclaimed; |
| unsigned int nr_pages = current->memcg_nr_pages_over_high; |
| int nr_retries = MAX_RECLAIM_RETRIES; |
| struct mem_cgroup *memcg; |
| bool in_retry = false; |
| |
| if (likely(!nr_pages)) |
| return; |
| |
| memcg = get_mem_cgroup_from_mm(current->mm); |
| current->memcg_nr_pages_over_high = 0; |
| |
| retry_reclaim: |
| /* |
| * Bail if the task is already exiting. Unlike memory.max, |
| * memory.high enforcement isn't as strict, and there is no |
| * OOM killer involved, which means the excess could already |
| * be much bigger (and still growing) than it could for |
| * memory.max; the dying task could get stuck in fruitless |
| * reclaim for a long time, which isn't desirable. |
| */ |
| if (task_is_dying()) |
| goto out; |
| |
| /* |
| * The allocating task should reclaim at least the batch size, but for |
| * subsequent retries we only want to do what's necessary to prevent oom |
| * or breaching resource isolation. |
| * |
| * This is distinct from memory.max or page allocator behaviour because |
| * memory.high is currently batched, whereas memory.max and the page |
| * allocator run every time an allocation is made. |
| */ |
| nr_reclaimed = reclaim_high(memcg, |
| in_retry ? SWAP_CLUSTER_MAX : nr_pages, |
| gfp_mask); |
| |
| /* |
| * memory.high is breached and reclaim is unable to keep up. Throttle |
| * allocators proactively to slow down excessive growth. |
| */ |
| penalty_jiffies = calculate_high_delay(memcg, nr_pages, |
| mem_find_max_overage(memcg)); |
| |
| penalty_jiffies += calculate_high_delay(memcg, nr_pages, |
| swap_find_max_overage(memcg)); |
| |
| /* |
| * Clamp the max delay per usermode return so as to still keep the |
| * application moving forwards and also permit diagnostics, albeit |
| * extremely slowly. |
| */ |
| penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES); |
| |
| /* |
| * Don't sleep if the amount of jiffies this memcg owes us is so low |
| * that it's not even worth doing, in an attempt to be nice to those who |
| * go only a small amount over their memory.high value and maybe haven't |
| * been aggressively reclaimed enough yet. |
| */ |
| if (penalty_jiffies <= HZ / 100) |
| goto out; |
| |
| /* |
| * If reclaim is making forward progress but we're still over |
| * memory.high, we want to encourage that rather than doing allocator |
| * throttling. |
| */ |
| if (nr_reclaimed || nr_retries--) { |
| in_retry = true; |
| goto retry_reclaim; |
| } |
| |
| /* |
| * Reclaim didn't manage to push usage below the limit, slow |
| * this allocating task down. |
| * |
| * If we exit early, we're guaranteed to die (since |
| * schedule_timeout_killable sets TASK_KILLABLE). This means we don't |
| * need to account for any ill-begotten jiffies to pay them off later. |
| */ |
| psi_memstall_enter(&pflags); |
| schedule_timeout_killable(penalty_jiffies); |
| psi_memstall_leave(&pflags); |
| |
| out: |
| css_put(&memcg->css); |
| } |
| |
| static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, |
| unsigned int nr_pages) |
| { |
| unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); |
| int nr_retries = MAX_RECLAIM_RETRIES; |
| struct mem_cgroup *mem_over_limit; |
| struct page_counter *counter; |
| unsigned long nr_reclaimed; |
| bool passed_oom = false; |
| unsigned int reclaim_options = MEMCG_RECLAIM_MAY_SWAP; |
| bool drained = false; |
| bool raised_max_event = false; |
| unsigned long pflags; |
| |
| retry: |
| if (consume_stock(memcg, nr_pages)) |
| return 0; |
| |
| if (!do_memsw_account() || |
| page_counter_try_charge(&memcg->memsw, batch, &counter)) { |
| if (page_counter_try_charge(&memcg->memory, batch, &counter)) |
| goto done_restock; |
| if (do_memsw_account()) |
| page_counter_uncharge(&memcg->memsw, batch); |
| mem_over_limit = mem_cgroup_from_counter(counter, memory); |
| } else { |
| mem_over_limit = mem_cgroup_from_counter(counter, memsw); |
| reclaim_options &= ~MEMCG_RECLAIM_MAY_SWAP; |
| } |
| |
| if (batch > nr_pages) { |
| batch = nr_pages; |
| goto retry; |
| } |
| |
| /* |
| * 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); |
| raised_max_event = true; |
| |
| psi_memstall_enter(&pflags); |
| nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, |
| gfp_mask, reclaim_options); |
| psi_memstall_leave(&pflags); |
| |
| if (mem_cgroup_margin(mem_over_limit) >= nr_pages) |
| goto retry; |
| |
| if (!drained) { |
| drain_all_stock(mem_over_limit); |
| drained = true; |
| goto retry; |
| } |
| |
| if (gfp_mask & __GFP_NORETRY) |
| goto nomem; |
| /* |
| * Even though the limit is exceeded at this point, reclaim |
| * may have been able to free some pages. Retry the charge |
| * before killing the task. |
| * |
| * Only for regular pages, though: huge pages are rather |
| * unlikely to succeed so close to the limit, and we fall back |
| * to regular pages anyway in case of failure. |
| */ |
| if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER)) |
| goto retry; |
| /* |
| * At task move, charge accounts can be doubly counted. So, it's |
| * better to wait until the end of task_move if something is going on. |
| */ |
| if (mem_cgroup_wait_acct_move(mem_over_limit)) |
| goto retry; |
| |
| if (nr_retries--) |
| goto retry; |
| |
| if (gfp_mask & __GFP_RETRY_MAYFAIL) |
| goto nomem; |
| |
| /* Avoid endless loop for tasks bypassed by the oom killer */ |
| if (passed_oom && task_is_dying()) |
| goto nomem; |
| |
| /* |
| * keep retrying as long as the memcg oom killer is able to make |
| * a forward progress or bypass the charge if the oom killer |
| * couldn't make any progress. |
| */ |
| if (mem_cgroup_oom(mem_over_limit, gfp_mask, |
| get_order(nr_pages * PAGE_SIZE))) { |
| passed_oom = true; |
| nr_retries = MAX_RECLAIM_RETRIES; |
| goto retry; |
| } |
| nomem: |
| /* |
| * 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_NOFAIL | __GFP_HIGH))) |
| return -ENOMEM; |
| force: |
| /* |
| * If the allocation has to be enforced, don't forget to raise |
| * a MEMCG_MAX event. |
| */ |
| if (!raised_max_event) |
| memcg_memory_event(mem_over_limit, MEMCG_MAX); |
| |
| /* |
| * The allocation either can't fail or will lead to more memory |
| * being freed very soon. Allow memory usage go over the limit |
| * temporarily by force charging it. |
| */ |
| page_counter_charge(&memcg->memory, nr_pages); |
| if (do_memsw_account()) |
| page_counter_charge(&memcg->memsw, nr_pages); |
| |
| return 0; |
| |
| done_restock: |
| if (batch > nr_pages) |
| refill_stock(memcg, batch - nr_pages); |
| |
| /* |
| * If the hierarchy is above the normal consumption range, schedule |
| * reclaim on returning to userland. We can perform reclaim here |
| * if __GFP_RECLAIM but let's always punt for simplicity and so that |
| * GFP_KERNEL can consistently be used during reclaim. @memcg is |
| * not recorded as it most likely matches current's and won't |
| * change in the meantime. As high limit is checked again before |
| * reclaim, the cost of mismatch is negligible. |
| */ |
| do { |
| bool mem_high, swap_high; |
| |
| mem_high = page_counter_read(&memcg->memory) > |
| READ_ONCE(memcg->memory.high); |
| swap_high = page_counter_read(&memcg->swap) > |
| READ_ONCE(memcg->swap.high); |
| |
| /* Don't bother a random interrupted task */ |
| if (!in_task()) { |
| if (mem_high) { |
| schedule_work(&memcg->high_work); |
| break; |
| } |
| continue; |
| } |
| |
| if (mem_high || swap_high) { |
| /* |
| * The allocating tasks in this cgroup will need to do |
| * reclaim or be throttled to prevent further growth |
| * of the memory or swap footprints. |
| * |
| * Target some best-effort fairness between the tasks, |
| * and distribute reclaim work and delay penalties |
| * based on how much each task is actually allocating. |
| */ |
| current->memcg_nr_pages_over_high += batch; |
| set_notify_resume(current); |
| break; |
| } |
| } while ((memcg = parent_mem_cgroup(memcg))); |
| |
| /* |
| * Reclaim is set up above to be called from the userland |
| * return path. But also attempt synchronous reclaim to avoid |
| * excessive overrun while the task is still inside the |
| * kernel. If this is successful, the return path will see it |
| * when it rechecks the overage and simply bail out. |
| */ |
| if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH && |
| !(current->flags & PF_MEMALLOC) && |
| gfpflags_allow_blocking(gfp_mask)) |
| mem_cgroup_handle_over_high(gfp_mask); |
| return 0; |
| } |
| |
| static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, |
| unsigned int nr_pages) |
| { |
| if (mem_cgroup_is_root(memcg)) |
| return 0; |
| |
| return try_charge_memcg(memcg, gfp_mask, nr_pages); |
| } |
| |
| /** |
| * mem_cgroup_cancel_charge() - cancel an uncommitted try_charge() call. |
| * @memcg: memcg previously charged. |
| * @nr_pages: number of pages previously charged. |
| */ |
| void mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) |
| { |
| if (mem_cgroup_is_root(memcg)) |
| return; |
| |
| page_counter_uncharge(&memcg->memory, nr_pages); |
| if (do_memsw_account()) |
| page_counter_uncharge(&memcg->memsw, nr_pages); |
| } |
| |
| static void commit_charge(struct folio *folio, struct mem_cgroup *memcg) |
| { |
| VM_BUG_ON_FOLIO(folio_memcg(folio), folio); |
| /* |
| * Any of the following ensures page's memcg stability: |
| * |
| * - the page lock |
| * - LRU isolation |
| * - folio_memcg_lock() |
| * - exclusive reference |
| * - mem_cgroup_trylock_pages() |
| */ |
| folio->memcg_data = (unsigned long)memcg; |
| } |
| |
| /** |
| * mem_cgroup_commit_charge - commit a previously successful try_charge(). |
| * @folio: folio to commit the charge to. |
| * @memcg: memcg previously charged. |
| */ |
| void mem_cgroup_commit_charge(struct folio *folio, struct mem_cgroup *memcg) |
| { |
| css_get(&memcg->css); |
| commit_charge(folio, memcg); |
| |
| local_irq_disable(); |
| mem_cgroup_charge_statistics(memcg, folio_nr_pages(folio)); |
| memcg_check_events(memcg, folio_nid(folio)); |
| local_irq_enable(); |
| } |
| |
| #ifdef CONFIG_MEMCG_KMEM |
| /* |
| * The allocated objcg pointers array is not accounted directly. |
| * Moreover, it should not come from DMA buffer and is not readily |
| * reclaimable. So those GFP bits should be masked off. |
| */ |
| #define OBJCGS_CLEAR_MASK (__GFP_DMA | __GFP_RECLAIMABLE | \ |
| __GFP_ACCOUNT | __GFP_NOFAIL) |
| |
| /* |
| * mod_objcg_mlstate() may be called with irq enabled, so |
| * mod_memcg_lruvec_state() should be used. |
| */ |
| static inline void mod_objcg_mlstate(struct obj_cgroup *objcg, |
| struct pglist_data *pgdat, |
| enum node_stat_item idx, int nr) |
| { |
| struct mem_cgroup *memcg; |
| struct lruvec *lruvec; |
| |
| rcu_read_lock(); |
| memcg = obj_cgroup_memcg(objcg); |
| lruvec = mem_cgroup_lruvec(memcg, pgdat); |
| mod_memcg_lruvec_state(lruvec, idx, nr); |
| rcu_read_unlock(); |
| } |
| |
| int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s, |
| gfp_t gfp, bool new_slab) |
| { |
| unsigned int objects = objs_per_slab(s, slab); |
| unsigned long memcg_data; |
| void *vec; |
| |
| gfp &= ~OBJCGS_CLEAR_MASK; |
| vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp, |
| slab_nid(slab)); |
| if (!vec) |
| return -ENOMEM; |
| |
| memcg_data = (unsigned long) vec | MEMCG_DATA_OBJCGS; |
| if (new_slab) { |
| /* |
| * If the slab is brand new and nobody can yet access its |
| * memcg_data, no synchronization is required and memcg_data can |
| * be simply assigned. |
| */ |
| slab->memcg_data = memcg_data; |
| } else if (cmpxchg(&slab->memcg_data, 0, memcg_data)) { |
| /* |
| * If the slab is already in use, somebody can allocate and |
| * assign obj_cgroups in parallel. In this case the existing |
| * objcg vector should be reused. |
| */ |
| kfree(vec); |
| return 0; |
| } |
| |
| kmemleak_not_leak(vec); |
| return 0; |
| } |
| |
| static __always_inline |
| struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p) |
| { |
| /* |
| * Slab objects are accounted individually, not per-page. |
| * Memcg membership data for each individual object is saved in |
| * slab->memcg_data. |
| */ |
| if (folio_test_slab(folio)) { |
| struct obj_cgroup **objcgs; |
| struct slab *slab; |
| unsigned int off; |
| |
| slab = folio_slab(folio); |
| objcgs = slab_objcgs(slab); |
| if (!objcgs) |
| return NULL; |
| |
| off = obj_to_index(slab->slab_cache, slab, p); |
| if (objcgs[off]) |
| return obj_cgroup_memcg(objcgs[off]); |
| |
| return NULL; |
| } |
| |
| /* |
| * folio_memcg_check() is used here, because in theory we can encounter |
| * a folio where the slab flag has been cleared already, but |
| * slab->memcg_data has not been freed yet |
| * folio_memcg_check() will guarantee that a proper memory |
| * cgroup pointer or NULL will be returned. |
| */ |
| return folio_memcg_check(folio); |
| } |
| |
| /* |
| * Returns a pointer to the memory cgroup to which the kernel object is charged. |
| * |
| * A passed kernel object can be a slab object, vmalloc object or a generic |
| * kernel page, so different mechanisms for getting the memory cgroup pointer |
| * should be used. |
| * |
| * In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller |
| * can not know for sure how the kernel object is implemented. |
| * mem_cgroup_from_obj() can be safely used in such cases. |
| * |
| * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(), |
| * cgroup_mutex, etc. |
| */ |
| struct mem_cgroup *mem_cgroup_from_obj(void *p) |
| { |
| struct folio *folio; |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| if (unlikely(is_vmalloc_addr(p))) |
| folio = page_folio(vmalloc_to_page(p)); |
| else |
| folio = virt_to_folio(p); |
| |
| return mem_cgroup_from_obj_folio(folio, p); |
| } |
| |
| /* |
| * Returns a pointer to the memory cgroup to which the kernel object is charged. |
| * Similar to mem_cgroup_from_obj(), but faster and not suitable for objects, |
| * allocated using vmalloc(). |
| * |
| * A passed kernel object must be a slab object or a generic kernel page. |
| * |
| * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(), |
| * cgroup_mutex, etc. |
| */ |
| struct mem_cgroup *mem_cgroup_from_slab_obj(void *p) |
| { |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| return mem_cgroup_from_obj_folio(virt_to_folio(p), p); |
| } |
| |
| static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg) |
| { |
| struct obj_cgroup *objcg = NULL; |
| |
| for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) { |
| objcg = rcu_dereference(memcg->objcg); |
| if (likely(objcg && obj_cgroup_tryget(objcg))) |
| break; |
| objcg = NULL; |
| } |
| return objcg; |
| } |
| |
| static struct obj_cgroup *current_objcg_update(void) |
| { |
| struct mem_cgroup *memcg; |
| struct obj_cgroup *old, *objcg = NULL; |
| |
| do { |
| /* Atomically drop the update bit. */ |
| old = xchg(¤t->objcg, NULL); |
| if (old) { |
| old = (struct obj_cgroup *) |
| ((unsigned long)old & ~CURRENT_OBJCG_UPDATE_FLAG); |
| if (old) |
| obj_cgroup_put(old); |
| |
| old = NULL; |
| } |
| |
| /* If new objcg is NULL, no reason for the second atomic update. */ |
| if (!current->mm || (current->flags & PF_KTHREAD)) |
| return NULL; |
| |
| /* |
| * Release the objcg pointer from the previous iteration, |
| * if try_cmpxcg() below fails. |
| */ |
| if (unlikely(objcg)) { |
| obj_cgroup_put(objcg); |
| objcg = NULL; |
| } |
| |
| /* |
| * Obtain the new objcg pointer. The current task can be |
| * asynchronously moved to another memcg and the previous |
| * memcg can be offlined. So let's get the memcg pointer |
| * and try get a reference to objcg under a rcu read lock. |
| */ |
| |
| rcu_read_lock(); |
| memcg = mem_cgroup_from_task(current); |
| objcg = __get_obj_cgroup_from_memcg(memcg); |
| rcu_read_unlock(); |
| |
| /* |
| * Try set up a new objcg pointer atomically. If it |
| * fails, it means the update flag was set concurrently, so |
| * the whole procedure should be repeated. |
| */ |
| } while (!try_cmpxchg(¤t->objcg, &old, objcg)); |
| |
| return objcg; |
| } |
| |
| __always_inline struct obj_cgroup *current_obj_cgroup(void) |
| { |
| struct mem_cgroup *memcg; |
| struct obj_cgroup *objcg; |
| |
| if (in_task()) { |
| memcg = current->active_memcg; |
| if (unlikely(memcg)) |
| goto from_memcg; |
| |
| objcg = READ_ONCE(current->objcg); |
| if (unlikely((unsigned long)objcg & CURRENT_OBJCG_UPDATE_FLAG)) |
| objcg = current_objcg_update(); |
| /* |
| * Objcg reference is kept by the task, so it's safe |
| * to use the objcg by the current task. |
| */ |
| return objcg; |
| } |
| |
| memcg = this_cpu_read(int_active_memcg); |
| if (unlikely(memcg)) |
| goto from_memcg; |
| |
| return NULL; |
| |
| from_memcg: |
| objcg = NULL; |
| for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) { |
| /* |
| * Memcg pointer is protected by scope (see set_active_memcg()) |
| * and is pinning the corresponding objcg, so objcg can't go |
| * away and can be used within the scope without any additional |
| * protection. |
| */ |
| objcg = rcu_dereference_check(memcg->objcg, 1); |
| if (likely(objcg)) |
| break; |
| } |
| |
| return objcg; |
| } |
| |
| struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio) |
| { |
| struct obj_cgroup *objcg; |
| |
| if (!memcg_kmem_online()) |
| return NULL; |
| |
| if (folio_memcg_kmem(folio)) { |
| objcg = __folio_objcg(folio); |
| obj_cgroup_get(objcg); |
| } else { |
| struct mem_cgroup *memcg; |
| |
| rcu_read_lock(); |
| memcg = __folio_memcg(folio); |
| if (memcg) |
| objcg = __get_obj_cgroup_from_memcg(memcg); |
| else |
| objcg = NULL; |
| rcu_read_unlock(); |
| } |
| return objcg; |
| } |
| |
| static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages) |
| { |
| mod_memcg_state(memcg, MEMCG_KMEM, nr_pages); |
| if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) { |
| if (nr_pages > 0) |
| page_counter_charge(&memcg->kmem, nr_pages); |
| else |
| page_counter_uncharge(&memcg->kmem, -nr_pages); |
| } |
| } |
| |
| |
| /* |
| * obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg |
| * @objcg: object cgroup to uncharge |
| * @nr_pages: number of pages to uncharge |
| */ |
| static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, |
| unsigned int nr_pages) |
| { |
| struct mem_cgroup *memcg; |
| |
| memcg = get_mem_cgroup_from_objcg(objcg); |
| |
| memcg_account_kmem(memcg, -nr_pages); |
| refill_stock(memcg, nr_pages); |
| |
| css_put(&memcg->css); |
| } |
| |
| /* |
| * obj_cgroup_charge_pages: charge a number of kernel pages to a objcg |
| * @objcg: object cgroup to charge |
| * @gfp: reclaim mode |
| * @nr_pages: number of pages to charge |
| * |
| * Returns 0 on success, an error code on failure. |
| */ |
| static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp, |
| unsigned int nr_pages) |
| { |
| struct mem_cgroup *memcg; |
| int ret; |
| |
| memcg = get_mem_cgroup_from_objcg(objcg); |
| |
| ret = try_charge_memcg(memcg, gfp, nr_pages); |
| if (ret) |
| goto out; |
| |
| memcg_account_kmem(memcg, nr_pages); |
| out: |
| css_put(&memcg->css); |
| |
| return ret; |
| } |
| |
| /** |
| * __memcg_kmem_charge_page: charge a kmem page to the current memory cgroup |
| * @page: page to charge |
| * @gfp: reclaim mode |
| * @order: allocation order |
| * |
| * Returns 0 on success, an error code on failure. |
| */ |
| int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order) |
| { |
| struct obj_cgroup *objcg; |
| int ret = 0; |
| |
| objcg = current_obj_cgroup(); |
| if (objcg) { |
| ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order); |
| if (!ret) { |
| obj_cgroup_get(objcg); |
| page->memcg_data = (unsigned long)objcg | |
| MEMCG_DATA_KMEM; |
| return 0; |
| } |
| } |
| return ret; |
| } |
| |
| /** |
| * __memcg_kmem_uncharge_page: uncharge a kmem page |
| * @page: page to uncharge |
| * @order: allocation order |
| */ |
| void __memcg_kmem_uncharge_page(struct page *page, int order) |
| { |
| struct folio *folio = page_folio(page); |
| struct obj_cgroup *objcg; |
| unsigned int nr_pages = 1 << order; |
| |
| if (!folio_memcg_kmem(folio)) |
| return; |
| |
| objcg = __folio_objcg(folio); |
| obj_cgroup_uncharge_pages(objcg, nr_pages); |
| folio->memcg_data = 0; |
| obj_cgroup_put(objcg); |
| } |
| |
| void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, |
| enum node_stat_item idx, int nr) |
| { |
| struct memcg_stock_pcp *stock; |
| struct obj_cgroup *old = NULL; |
| unsigned long flags; |
| int *bytes; |
| |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| stock = this_cpu_ptr(&memcg_stock); |
| |
| /* |
| * Save vmstat data in stock and skip vmstat array update unless |
| * accumulating over a page of vmstat data or when pgdat or idx |
| * changes. |
| */ |
| if (READ_ONCE(stock->cached_objcg) != objcg) { |
| old = drain_obj_stock(stock); |
| obj_cgroup_get(objcg); |
| stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) |
| ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; |
| WRITE_ONCE(stock->cached_objcg, objcg); |
| stock->cached_pgdat = pgdat; |
| } else if (stock->cached_pgdat != pgdat) { |
| /* Flush the existing cached vmstat data */ |
| struct pglist_data *oldpg = stock->cached_pgdat; |
| |
| if (stock->nr_slab_reclaimable_b) { |
| mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B, |
| stock->nr_slab_reclaimable_b); |
| stock->nr_slab_reclaimable_b = 0; |
| } |
| if (stock->nr_slab_unreclaimable_b) { |
| mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B, |
| stock->nr_slab_unreclaimable_b); |
| stock->nr_slab_unreclaimable_b = 0; |
| |