| // 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/cgroup-defs.h> |
| #include <linux/page_counter.h> |
| #include <linux/memcontrol.h> |
| #include <linux/cgroup.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/list.h> |
| #include <linux/mutex.h> |
| #include <linux/rbtree.h> |
| #include <linux/slab.h> |
| #include <linux/swapops.h> |
| #include <linux/spinlock.h> |
| #include <linux/fs.h> |
| #include <linux/seq_file.h> |
| #include <linux/parser.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/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 "memcontrol-v1.h" |
| |
| #include <linux/uaccess.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/memcg.h> |
| #undef CREATE_TRACE_POINTS |
| |
| #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 |
| |
| 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 SEQ_BUF_SIZE SZ_4K |
| #define CURRENT_OBJCG_UPDATE_BIT 0 |
| #define CURRENT_OBJCG_UPDATE_FLAG (1UL << CURRENT_OBJCG_UPDATE_BIT) |
| |
| 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_post_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); |
| |
| /** |
| * 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; |
| } |
| |
| /* Subset of node_stat_item for memcg stats */ |
| static const unsigned int memcg_node_stat_items[] = { |
| NR_INACTIVE_ANON, |
| NR_ACTIVE_ANON, |
| NR_INACTIVE_FILE, |
| NR_ACTIVE_FILE, |
| NR_UNEVICTABLE, |
| NR_SLAB_RECLAIMABLE_B, |
| NR_SLAB_UNRECLAIMABLE_B, |
| WORKINGSET_REFAULT_ANON, |
| WORKINGSET_REFAULT_FILE, |
| WORKINGSET_ACTIVATE_ANON, |
| WORKINGSET_ACTIVATE_FILE, |
| WORKINGSET_RESTORE_ANON, |
| WORKINGSET_RESTORE_FILE, |
| WORKINGSET_NODERECLAIM, |
| NR_ANON_MAPPED, |
| NR_FILE_MAPPED, |
| NR_FILE_PAGES, |
| NR_FILE_DIRTY, |
| NR_WRITEBACK, |
| NR_SHMEM, |
| NR_SHMEM_THPS, |
| NR_FILE_THPS, |
| NR_ANON_THPS, |
| NR_KERNEL_STACK_KB, |
| NR_PAGETABLE, |
| NR_SECONDARY_PAGETABLE, |
| #ifdef CONFIG_SWAP |
| NR_SWAPCACHE, |
| #endif |
| #ifdef CONFIG_NUMA_BALANCING |
| PGPROMOTE_SUCCESS, |
| #endif |
| PGDEMOTE_KSWAPD, |
| PGDEMOTE_DIRECT, |
| PGDEMOTE_KHUGEPAGED, |
| #ifdef CONFIG_HUGETLB_PAGE |
| NR_HUGETLB, |
| #endif |
| }; |
| |
| static const unsigned int memcg_stat_items[] = { |
| MEMCG_SWAP, |
| MEMCG_SOCK, |
| MEMCG_PERCPU_B, |
| MEMCG_VMALLOC, |
| MEMCG_KMEM, |
| MEMCG_ZSWAP_B, |
| MEMCG_ZSWAPPED, |
| }; |
| |
| #define NR_MEMCG_NODE_STAT_ITEMS ARRAY_SIZE(memcg_node_stat_items) |
| #define MEMCG_VMSTAT_SIZE (NR_MEMCG_NODE_STAT_ITEMS + \ |
| ARRAY_SIZE(memcg_stat_items)) |
| #define BAD_STAT_IDX(index) ((u32)(index) >= U8_MAX) |
| static u8 mem_cgroup_stats_index[MEMCG_NR_STAT] __read_mostly; |
| |
| static void init_memcg_stats(void) |
| { |
| u8 i, j = 0; |
| |
| BUILD_BUG_ON(MEMCG_NR_STAT >= U8_MAX); |
| |
| memset(mem_cgroup_stats_index, U8_MAX, sizeof(mem_cgroup_stats_index)); |
| |
| for (i = 0; i < NR_MEMCG_NODE_STAT_ITEMS; ++i, ++j) |
| mem_cgroup_stats_index[memcg_node_stat_items[i]] = j; |
| |
| for (i = 0; i < ARRAY_SIZE(memcg_stat_items); ++i, ++j) |
| mem_cgroup_stats_index[memcg_stat_items[i]] = j; |
| } |
| |
| static inline int memcg_stats_index(int idx) |
| { |
| return mem_cgroup_stats_index[idx]; |
| } |
| |
| struct lruvec_stats_percpu { |
| /* Local (CPU and cgroup) state */ |
| long state[NR_MEMCG_NODE_STAT_ITEMS]; |
| |
| /* Delta calculation for lockless upward propagation */ |
| long state_prev[NR_MEMCG_NODE_STAT_ITEMS]; |
| }; |
| |
| struct lruvec_stats { |
| /* Aggregated (CPU and subtree) state */ |
| long state[NR_MEMCG_NODE_STAT_ITEMS]; |
| |
| /* Non-hierarchical (CPU aggregated) state */ |
| long state_local[NR_MEMCG_NODE_STAT_ITEMS]; |
| |
| /* Pending child counts during tree propagation */ |
| long state_pending[NR_MEMCG_NODE_STAT_ITEMS]; |
| }; |
| |
| unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx) |
| { |
| struct mem_cgroup_per_node *pn; |
| long x; |
| int i; |
| |
| if (mem_cgroup_disabled()) |
| return node_page_state(lruvec_pgdat(lruvec), idx); |
| |
| i = memcg_stats_index(idx); |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return 0; |
| |
| pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); |
| x = READ_ONCE(pn->lruvec_stats->state[i]); |
| #ifdef CONFIG_SMP |
| if (x < 0) |
| x = 0; |
| #endif |
| return x; |
| } |
| |
| unsigned long lruvec_page_state_local(struct lruvec *lruvec, |
| enum node_stat_item idx) |
| { |
| struct mem_cgroup_per_node *pn; |
| long x; |
| int i; |
| |
| if (mem_cgroup_disabled()) |
| return node_page_state(lruvec_pgdat(lruvec), idx); |
| |
| i = memcg_stats_index(idx); |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return 0; |
| |
| pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); |
| x = READ_ONCE(pn->lruvec_stats->state_local[i]); |
| #ifdef CONFIG_SMP |
| if (x < 0) |
| x = 0; |
| #endif |
| return x; |
| } |
| |
| /* Subset of vm_event_item to report for memcg event stats */ |
| static const unsigned int memcg_vm_event_stat[] = { |
| #ifdef CONFIG_MEMCG_V1 |
| PGPGIN, |
| PGPGOUT, |
| #endif |
| PSWPIN, |
| PSWPOUT, |
| PGSCAN_KSWAPD, |
| PGSCAN_DIRECT, |
| PGSCAN_KHUGEPAGED, |
| PGSTEAL_KSWAPD, |
| PGSTEAL_DIRECT, |
| PGSTEAL_KHUGEPAGED, |
| PGFAULT, |
| PGMAJFAULT, |
| PGREFILL, |
| PGACTIVATE, |
| PGDEACTIVATE, |
| PGLAZYFREE, |
| PGLAZYFREED, |
| #ifdef CONFIG_SWAP |
| SWPIN_ZERO, |
| SWPOUT_ZERO, |
| #endif |
| #ifdef CONFIG_ZSWAP |
| ZSWPIN, |
| ZSWPOUT, |
| ZSWPWB, |
| #endif |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| THP_FAULT_ALLOC, |
| THP_COLLAPSE_ALLOC, |
| THP_SWPOUT, |
| THP_SWPOUT_FALLBACK, |
| #endif |
| #ifdef CONFIG_NUMA_BALANCING |
| NUMA_PAGE_MIGRATE, |
| NUMA_PTE_UPDATES, |
| NUMA_HINT_FAULTS, |
| #endif |
| }; |
| |
| #define NR_MEMCG_EVENTS ARRAY_SIZE(memcg_vm_event_stat) |
| static u8 mem_cgroup_events_index[NR_VM_EVENT_ITEMS] __read_mostly; |
| |
| static void init_memcg_events(void) |
| { |
| u8 i; |
| |
| BUILD_BUG_ON(NR_VM_EVENT_ITEMS >= U8_MAX); |
| |
| memset(mem_cgroup_events_index, U8_MAX, |
| sizeof(mem_cgroup_events_index)); |
| |
| for (i = 0; i < NR_MEMCG_EVENTS; ++i) |
| mem_cgroup_events_index[memcg_vm_event_stat[i]] = i; |
| } |
| |
| static inline int memcg_events_index(enum vm_event_item idx) |
| { |
| return mem_cgroup_events_index[idx]; |
| } |
| |
| 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_VMSTAT_SIZE]; |
| unsigned long events[NR_MEMCG_EVENTS]; |
| |
| /* Delta calculation for lockless upward propagation */ |
| long state_prev[MEMCG_VMSTAT_SIZE]; |
| unsigned long events_prev[NR_MEMCG_EVENTS]; |
| } ____cacheline_aligned; |
| |
| struct memcg_vmstats { |
| /* Aggregated (CPU and subtree) page state & events */ |
| long state[MEMCG_VMSTAT_SIZE]; |
| unsigned long events[NR_MEMCG_EVENTS]; |
| |
| /* Non-hierarchical (CPU aggregated) page state & events */ |
| long state_local[MEMCG_VMSTAT_SIZE]; |
| unsigned long events_local[NR_MEMCG_EVENTS]; |
| |
| /* Pending child counts during tree propagation */ |
| long state_pending[MEMCG_VMSTAT_SIZE]; |
| 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(); |
| unsigned int stats_updates; |
| |
| if (!val) |
| return; |
| |
| cgroup_rstat_updated(memcg->css.cgroup, cpu); |
| statc = this_cpu_ptr(memcg->vmstats_percpu); |
| for (; statc; statc = statc->parent) { |
| stats_updates = READ_ONCE(statc->stats_updates) + abs(val); |
| WRITE_ONCE(statc->stats_updates, stats_updates); |
| if (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(stats_updates, |
| &statc->vmstats->stats_updates); |
| WRITE_ONCE(statc->stats_updates, 0); |
| } |
| } |
| |
| static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) |
| { |
| bool needs_flush = memcg_vmstats_needs_flush(memcg->vmstats); |
| |
| trace_memcg_flush_stats(memcg, atomic64_read(&memcg->vmstats->stats_updates), |
| force, needs_flush); |
| |
| if (!force && !needs_flush) |
| return; |
| |
| 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; |
| |
| __mem_cgroup_flush_stats(memcg, false); |
| } |
| |
| 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. |
| */ |
| __mem_cgroup_flush_stats(root_mem_cgroup, true); |
| queue_delayed_work(system_unbound_wq, &stats_flush_dwork, FLUSH_TIME); |
| } |
| |
| unsigned long memcg_page_state(struct mem_cgroup *memcg, int idx) |
| { |
| long x; |
| int i = memcg_stats_index(idx); |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return 0; |
| |
| x = READ_ONCE(memcg->vmstats->state[i]); |
| #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, enum memcg_stat_item idx, |
| int val) |
| { |
| int i = memcg_stats_index(idx); |
| |
| if (mem_cgroup_disabled()) |
| return; |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return; |
| |
| __this_cpu_add(memcg->vmstats_percpu->state[i], val); |
| val = memcg_state_val_in_pages(idx, val); |
| memcg_rstat_updated(memcg, val); |
| trace_mod_memcg_state(memcg, idx, val); |
| } |
| |
| /* idx can be of type enum memcg_stat_item or node_stat_item. */ |
| unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx) |
| { |
| long x; |
| int i = memcg_stats_index(idx); |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return 0; |
| |
| x = READ_ONCE(memcg->vmstats->state_local[i]); |
| #ifdef CONFIG_SMP |
| if (x < 0) |
| x = 0; |
| #endif |
| return x; |
| } |
| |
| static 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; |
| int i = memcg_stats_index(idx); |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return; |
| |
| 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: |
| WARN_ON_ONCE(!in_task()); |
| break; |
| default: |
| VM_WARN_ON_IRQS_ENABLED(); |
| } |
| } |
| |
| /* Update memcg */ |
| __this_cpu_add(memcg->vmstats_percpu->state[i], val); |
| |
| /* Update lruvec */ |
| __this_cpu_add(pn->lruvec_stats_percpu->state[i], val); |
| |
| val = memcg_state_val_in_pages(idx, val); |
| memcg_rstat_updated(memcg, val); |
| trace_mod_memcg_lruvec_state(memcg, 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 i = memcg_events_index(idx); |
| |
| if (mem_cgroup_disabled()) |
| return; |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) |
| return; |
| |
| memcg_stats_lock(); |
| __this_cpu_add(memcg->vmstats_percpu->events[i], count); |
| memcg_rstat_updated(memcg, count); |
| trace_count_memcg_events(memcg, idx, count); |
| memcg_stats_unlock(); |
| } |
| |
| unsigned long memcg_events(struct mem_cgroup *memcg, int event) |
| { |
| int i = memcg_events_index(event); |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, event)) |
| return 0; |
| |
| return READ_ONCE(memcg->vmstats->events[i]); |
| } |
| |
| unsigned long memcg_events_local(struct mem_cgroup *memcg, int event) |
| { |
| int i = memcg_events_index(event); |
| |
| if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, event)) |
| return 0; |
| |
| return READ_ONCE(memcg->vmstats->events_local[i]); |
| } |
| |
| 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; |
| } |
| |
| /** |
| * get_mem_cgroup_from_folio - Obtain a reference on a given folio's memcg. |
| * @folio: folio from which memcg should be extracted. |
| */ |
| struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio) |
| { |
| struct mem_cgroup *memcg = folio_memcg(folio); |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| rcu_read_lock(); |
| if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css))) |
| memcg = root_mem_cgroup; |
| 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; |
| struct mem_cgroup *pos; |
| struct mem_cgroup *next; |
| |
| if (mem_cgroup_disabled()) |
| return NULL; |
| |
| if (!root) |
| root = root_mem_cgroup; |
| |
| rcu_read_lock(); |
| restart: |
| next = NULL; |
| |
| if (reclaim) { |
| int gen; |
| int nid = reclaim->pgdat->node_id; |
| |
| iter = &root->nodeinfo[nid]->iter; |
| gen = atomic_read(&iter->generation); |
| |
| /* |
| * On start, join the current reclaim iteration cycle. |
| * Exit when a concurrent walker completes it. |
| */ |
| if (!prev) |
| reclaim->generation = gen; |
| else if (reclaim->generation != gen) |
| goto out_unlock; |
| |
| pos = READ_ONCE(iter->position); |
| } else |
| pos = prev; |
| |
| css = pos ? &pos->css : NULL; |
| |
| while ((css = css_next_descendant_pre(css, &root->css))) { |
| /* |
| * 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)) |
| break; |
| } |
| |
| next = mem_cgroup_from_css(css); |
| |
| 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. |
| */ |
| if (cmpxchg(&iter->position, pos, next) != pos) { |
| if (css && css != &root->css) |
| css_put(css); |
| goto restart; |
| } |
| |
| if (!next) { |
| atomic_inc(&iter->generation); |
| |
| /* |
| * 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) |
| goto restart; |
| } |
| } |
| |
| out_unlock: |
| rcu_read_unlock(); |
| if (prev && prev != root) |
| css_put(&prev->css); |
| |
| return next; |
| } |
| |
| /** |
| * 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 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 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 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; |
| } |
| |
| 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 }, |
| #ifdef 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 }, |
| #ifdef CONFIG_HUGETLB_PAGE |
| { "hugetlb", NR_HUGETLB }, |
| #endif |
| |
| /* 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 }, |
| |
| { "pgdemote_kswapd", PGDEMOTE_KSWAPD }, |
| { "pgdemote_direct", PGDEMOTE_DIRECT }, |
| { "pgdemote_khugepaged", PGDEMOTE_KHUGEPAGED }, |
| #ifdef CONFIG_NUMA_BALANCING |
| { "pgpromote_success", PGPROMOTE_SUCCESS }, |
| #endif |
| }; |
| |
| /* 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. |
| * |
| * Demotion and promotion activities are exported in pages, consistent |
| * with their global counterparts. |
| */ |
| 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: |
| case PGDEMOTE_KSWAPD: |
| case PGDEMOTE_DIRECT: |
| case PGDEMOTE_KHUGEPAGED: |
| #ifdef CONFIG_NUMA_BALANCING |
| case PGPROMOTE_SUCCESS: |
| #endif |
| return 1; |
| default: |
| return memcg_page_state_unit(item); |
| } |
| } |
| |
| unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item) |
| { |
| return memcg_page_state(memcg, item) * |
| memcg_page_state_output_unit(item); |
| } |
| |
| 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; |
| |
| #ifdef CONFIG_HUGETLB_PAGE |
| if (unlikely(memory_stats[i].idx == NR_HUGETLB) && |
| !(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING)) |
| continue; |
| #endif |
| 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++) { |
| #ifdef CONFIG_MEMCG_V1 |
| if (memcg_vm_event_stat[i] == PGPGIN || |
| memcg_vm_event_stat[i] == PGPGOUT) |
| continue; |
| #endif |
| seq_buf_printf(s, "%s %lu\n", |
| vm_event_name(memcg_vm_event_stat[i]), |
| memcg_events(memcg, memcg_vm_event_stat[i])); |
| } |
| } |
| |
| 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); |
| if (seq_buf_has_overflowed(s)) |
| pr_warn("%s: Warning, stat buffer overflow, please report\n", __func__); |
| } |
| |
| /** |
| * 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[SEQ_BUF_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); |
| #ifdef CONFIG_MEMCG_V1 |
| 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); |
| } |
| #endif |
| |
| pr_info("Memory cgroup stats for "); |
| pr_cont_cgroup_path(memcg->css.cgroup); |
| pr_cont(":"); |
| seq_buf_init(&s, buf, SEQ_BUF_SIZE); |
| 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; |
| } |
| |
| /* |
| * 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); |
| |
| if (!memcg1_oom_prepare(memcg, &locked)) |
| return false; |
| |
| ret = mem_cgroup_out_of_memory(memcg, mask, order); |
| |
| memcg1_oom_finish(memcg, locked); |
| |
| return ret; |
| } |
| |
| /** |
| * 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"); |
| } |
| |
| struct memcg_stock_pcp { |
| local_lock_t stock_lock; |
| struct mem_cgroup *cached; /* this never be root cgroup */ |
| unsigned int nr_pages; |
| |
| struct obj_cgroup *cached_objcg; |
| struct pglist_data *cached_pgdat; |
| unsigned int nr_bytes; |
| int nr_slab_reclaimable_b; |
| int nr_slab_unreclaimable_b; |
| |
| 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); |
| |
| 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); |
| |
| /** |
| * 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 int stock_pages; |
| 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); |
| stock_pages = READ_ONCE(stock->nr_pages); |
| if (memcg == READ_ONCE(stock->cached) && stock_pages >= nr_pages) { |
| WRITE_ONCE(stock->nr_pages, stock_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) |
| { |
| unsigned int stock_pages = READ_ONCE(stock->nr_pages); |
| struct mem_cgroup *old = READ_ONCE(stock->cached); |
| |
| if (!old) |
| return; |
| |
| if (stock_pages) { |
| page_counter_uncharge(&old->memory, stock_pages); |
| if (do_memsw_account()) |
| page_counter_uncharge(&old->memsw, stock_pages); |
| |
| WRITE_ONCE(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); |
| 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; |
| unsigned int stock_pages; |
| |
| 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_pages = READ_ONCE(stock->nr_pages) + nr_pages; |
| WRITE_ONCE(stock->nr_pages, stock_pages); |
| |
| if (stock_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. |
| */ |
| 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 && READ_ONCE(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, |
| NULL); |
| 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); |
| } |
| |
| 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, NULL); |
| 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; |
| |
| 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; |
| } |
| |
| /** |
| * 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_charged(folio), folio); |
| /* |
| * Any of the following ensures page's memcg stability: |
| * |
| * - the page lock |
| * - LRU isolation |
| * - exclusive reference |
| */ |
| 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); |
| memcg1_commit_charge(folio, memcg); |
| } |
| |
| 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(); |
| } |
| |
| 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->obj_exts. |
| */ |
| if (folio_test_slab(folio)) { |
| struct slabobj_ext *obj_exts; |
| struct slab *slab; |
| unsigned int off; |
| |
| slab = folio_slab(folio); |
| obj_exts = slab_obj_exts(slab); |
| if (!obj_exts) |
| return NULL; |
| |
| off = obj_to_index(slab->slab_cache, slab, p); |
| if (obj_exts[off].objcg) |
| return obj_cgroup_memcg(obj_exts[off].objcg); |
| |
| 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->obj_exts 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. |
| * It is 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); |
| 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; |
| } |
| |
| /* |
| * 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); |
| |
| mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); |
| memcg1_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; |
| |
| mod_memcg_state(memcg, MEMCG_KMEM, nr_pages); |
| memcg1_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); |
| } |
| |
| static 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; |
| } |
| stock->cached_pgdat = pgdat; |
| } |
| |
| bytes = (idx == NR_SLAB_RECLAIMABLE_B) ? &stock->nr_slab_reclaimable_b |
| : &stock->nr_slab_unreclaimable_b; |
| /* |
| * Even for large object >= PAGE_SIZE, the vmstat data will still be |
| * cached locally at least once before pushing it out. |
| */ |
| if (!*bytes) { |
| *bytes = nr; |
| nr = 0; |
| } else { |
| *bytes += nr; |
| if (abs(*bytes) > PAGE_SIZE) { |
| nr = *bytes; |
| *bytes = 0; |
| } else { |
| nr = 0; |
| } |
| } |
| if (nr) |
| __mod_objcg_mlstate(objcg, pgdat, idx, nr); |
| |
| local_unlock_irqrestore(&memcg_stock.stock_lock, flags); |
| obj_cgroup_put(old); |
| } |
| |
| static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) |
| { |
| struct memcg_stock_pcp *stock; |
| unsigned long flags; |
| bool ret = false; |
| |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| |
| stock = this_cpu_ptr(&memcg_stock); |
| if (objcg == READ_ONCE(stock->cached_objcg) && stock->nr_bytes >= nr_bytes) { |
| stock->nr_bytes -= nr_bytes; |
| ret = true; |
| } |
| |
| local_unlock_irqrestore(&memcg_stock.stock_lock, flags); |
| |
| return ret; |
| } |
| |
| static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) |
| { |
| struct obj_cgroup *old = READ_ONCE(stock->cached_objcg); |
| |
| if (!old) |
| return NULL; |
| |
| if (stock->nr_bytes) { |
| unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT; |
| unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1); |
| |
| if (nr_pages) { |
| struct mem_cgroup *memcg; |
| |
| memcg = get_mem_cgroup_from_objcg(old); |
| |
| mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); |
| memcg1_account_kmem(memcg, -nr_pages); |
| __refill_stock(memcg, nr_pages); |
| |
| css_put(&memcg->css); |
| } |
| |
| /* |
| * The leftover is flushed to the centralized per-memcg value. |
| * On the next attempt to refill obj stock it will be moved |
| * to a per-cpu stock (probably, on an other CPU), see |
| * refill_obj_stock(). |
| * |
| * How often it's flushed is a trade-off between the memory |
| * limit enforcement accuracy and potential CPU contention, |
| * so it might be changed in the future. |
| */ |
| atomic_add(nr_bytes, &old->nr_charged_bytes); |
| stock->nr_bytes = 0; |
| } |
| |
| /* |
| * Flush the vmstat data in current stock |
| */ |
| if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) { |
| if (stock->nr_slab_reclaimable_b) { |
| __mod_objcg_mlstate(old, stock->cached_pgdat, |
| NR_SLAB_RECLAIMABLE_B, |
| stock->nr_slab_reclaimable_b); |
| stock->nr_slab_reclaimable_b = 0; |
| } |
| if (stock->nr_slab_unreclaimable_b) { |
| __mod_objcg_mlstate(old, stock->cached_pgdat, |
| NR_SLAB_UNRECLAIMABLE_B, |
| stock->nr_slab_unreclaimable_b); |
| stock->nr_slab_unreclaimable_b = 0; |
| } |
| stock->cached_pgdat = NULL; |
| } |
| |
| WRITE_ONCE(stock->cached_objcg, NULL); |
| /* |
| * The `old' objects needs to be released by the caller via |
| * obj_cgroup_put() outside of memcg_stock_pcp::stock_lock. |
| */ |
| return old; |
| } |
| |
| static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, |
| struct mem_cgroup *root_memcg) |
| { |
| struct obj_cgroup *objcg = READ_ONCE(stock->cached_objcg); |
| struct mem_cgroup *memcg; |
| |
| if (objcg) { |
| memcg = obj_cgroup_memcg(objcg); |
| if (memcg && mem_cgroup_is_descendant(memcg, root_memcg)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, |
| bool allow_uncharge) |
| { |
| struct memcg_stock_pcp *stock; |
| struct obj_cgroup *old = NULL; |
| unsigned long flags; |
| unsigned int nr_pages = 0; |
| |
| local_lock_irqsave(&memcg_stock.stock_lock, flags); |
| |
| stock = this_cpu_ptr(&memcg_stock); |
| if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */ |
| old = drain_obj_stock(stock); |
| obj_cgroup_get(objcg); |
| WRITE_ONCE(stock->cached_objcg, objcg); |
| stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) |
| ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; |
| allow_uncharge = true; /* Allow uncharge when objcg changes */ |
| } |
| stock->nr_bytes += nr_bytes; |
| |
| if (allow_uncharge && (stock->nr_bytes > PAGE_SIZE)) { |
| nr_pages = stock->nr_bytes >> PAGE_SHIFT; |
| stock->nr_bytes &= (PAGE_SIZE - 1); |
| } |
| |
| local_unlock_irqrestore(&memcg_stock.stock_lock, flags); |
| obj_cgroup_put(old); |
| |
| if (nr_pages) |
| obj_cgroup_uncharge_pages(objcg, nr_pages); |
| } |
| |
| int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size) |
| { |
| unsigned int nr_pages, nr_bytes; |
| int ret; |
| |
| if (consume_obj_stock(objcg, size)) |
| return 0; |
| |
| /* |
| * In theory, objcg->nr_charged_bytes can have enough |
| * pre-charged bytes to satisfy the allocation. However, |
| * flushing objcg->nr_charged_bytes requires two atomic |
| * operations, and objcg->nr_charged_bytes can't be big. |
| * The shared objcg->nr_charged_bytes can also become a |
| * performance bottleneck if all tasks of the same memcg are |
| * trying to update it. So it's better to ignore it and try |
| * grab some new pages. The stock's nr_bytes will be flushed to |
| * objcg->nr_charged_bytes later on when objcg changes. |
| * |
| * The stock's nr_bytes may contain enough pre-charged bytes |
| * to allow one less page from being charged, but we can't rely |
| * on the pre-charged bytes not being changed outside of |
| * consume_obj_stock() or refill_obj_stock(). So ignore those |
| * pre-charged bytes as well when charging pages. To avoid a |
| * page uncharge right after a page charge, we set the |
| * allow_uncharge flag to false when calling refill_obj_stock() |
| * to temporarily allow the pre-charged bytes to exceed the page |
| * size limit. The maximum reachable value of the pre-charged |
| * bytes is (sizeof(object) + PAGE_SIZE - 2) if there is no data |
| * race. |
| */ |
| nr_pages = size >> PAGE_SHIFT; |
| nr_bytes = size & (PAGE_SIZE - 1); |
| |
| if (nr_bytes) |
| nr_pages += 1; |
| |
| ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages); |
| if (!ret && nr_bytes) |
| refill_obj_stock(objcg, PAGE_SIZE - nr_bytes, false); |
| |
| return ret; |
| } |
| |
| void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size) |
| { |
| refill_obj_stock(objcg, size, true); |
| } |
| |
| static inline size_t obj_full_size(struct kmem_cache *s) |
| { |
| /* |
| * For each accounted object there is an extra space which is used |
| * to store obj_cgroup membership. Charge it too. |
| */ |
| return s->size + sizeof(struct obj_cgroup *); |
| } |
| |
| bool __memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru, |
| gfp_t flags, size_t size, void **p) |
| { |
| struct obj_cgroup *objcg; |
| struct slab *slab; |
| unsigned long off; |
| size_t i; |
| |
| /* |
| * The obtained objcg pointer is safe to use within the current scope, |
| * defined by current task or set_active_memcg() pair. |
| * obj_cgroup_get() is used to get a permanent reference. |
| */ |
| objcg = current_obj_cgroup(); |
| if (!objcg) |
| return true; |
| |
| /* |
| * slab_alloc_node() avoids the NULL check, so we might be called with a |
| * single NULL object. kmem_cache_alloc_bulk() aborts if it can't fill |
| * the whole requested size. |
| * return success as there's nothing to free back |
| */ |
| if (unlikely(*p == NULL)) |
| return true; |
| |
| flags &= gfp_allowed_mask; |
| |
| if (lru) { |
| int ret; |
| struct mem_cgroup *memcg; |
| |
| memcg = get_mem_cgroup_from_objcg(objcg); |
| ret = memcg_list_lru_alloc(memcg, lru, flags); |
| css_put(&memcg->css); |
| |
| if (ret) |
| return false; |
| } |
| |
| if (obj_cgroup_charge(objcg, flags, size * obj_full_size(s))) |
| return false; |
| |
| for (i = 0; i < size; i++) { |
| slab = virt_to_slab(p[i]); |
| |
| if (!slab_obj_exts(slab) && |
| alloc_slab_obj_exts(slab, s, flags, false)) { |
| obj_cgroup_uncharge(objcg, obj_full_size(s)); |
| continue; |
| } |
| |
| off = obj_to_index(s, slab, p[i]); |
| obj_cgroup_get(objcg); |
| slab_obj_exts(slab)[off].objcg = objcg; |
| mod_objcg_state(objcg, slab_pgdat(slab), |
| cache_vmstat_idx(s), obj_full_size(s)); |
| } |
| |
| return true; |
| } |
| |
| void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, |
| void **p, int objects, struct slabobj_ext *obj_exts) |
| { |
| for (int i = 0; i < objects; i++) { |
| struct obj_cgroup *objcg; |
| unsigned int off; |
| |
| off = obj_to_index(s, slab, p[i]); |
| objcg = obj_exts[off].objcg; |
| if (!objcg) |
| continue; |
| |
| obj_exts[off].objcg = NULL; |
| obj_cgroup_uncharge(objcg, obj_full_size(s)); |
| mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s), |
| -obj_full_size(s)); |
| obj_cgroup_put(objcg); |
| } |
| } |
| |
| /* |
| * Because folio_memcg(head) is not set on tails, set it now. |
| */ |
| void split_page_memcg(struct page *head, int old_order, int new_order) |
| { |
| struct folio *folio = page_folio(head); |
| int i; |
| unsigned int old_nr = 1 << old_order; |
| unsigned int new_nr = 1 << new_order; |
| |
| if (mem_cgroup_disabled() || !folio_memcg_charged(folio)) |
| return; |
| |
| for (i = new_nr; i < old_nr; i += new_nr) |
| folio_page(folio, i)->memcg_data = folio->memcg_data; |
| |
| if (folio_memcg_kmem(folio)) |
| obj_cgroup_get_many(__folio_objcg(folio), old_nr / new_nr - 1); |
| else |
| css_get_many(&folio_memcg(folio)->css, old_nr / new_nr - 1); |
| } |
| |
| unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) |
| { |
| unsigned long val; |
| |
| if (mem_cgroup_is_root(memcg)) { |
| /* |
| * Approximate root's usage from global state. This isn't |
| * perfect, but the root usage was always an approximation. |
| */ |
| val = global_node_page_state(NR_FILE_PAGES) + |
| global_node_page_state(NR_ANON_MAPPED); |
| if (swap) |
| val += total_swap_pages - get_nr_swap_pages(); |
| } else { |
| if (!swap) |
| val = page_counter_read(&memcg->memory); |
| else |
| val = page_counter_read(&memcg->memsw); |
| } |
| return val; |
| } |
| |
| static int memcg_online_kmem(struct mem_cgroup *memcg) |
| { |
| struct obj_cgroup *objcg; |
| |
| if (mem_cgroup_kmem_disabled()) |
| return 0; |
| |
| if (unlikely(mem_cgroup_is_root(memcg))) |
| return 0; |
| |
| objcg = obj_cgroup_alloc(); |
| if (!objcg) |
| return -ENOMEM; |
| |
| objcg->memcg = memcg; |
| rcu_assign_pointer(memcg->objcg, objcg); |
| obj_cgroup_get(objcg); |
| memcg->orig_objcg = objcg; |
| |
| static_branch_enable(&memcg_kmem_online_key); |
| |
| memcg->kmemcg_id = memcg->id.id; |
| |
| return 0; |
| } |
| |
| static void memcg_offline_kmem(struct mem_cgroup *memcg) |
| { |
| struct mem_cgroup *parent; |
| |
| if (mem_cgroup_kmem_disabled()) |
| return; |
| |
| if (unlikely(mem_cgroup_is_root(memcg))) |
| return; |
| |
| parent = parent_mem_cgroup(memcg); |
| if (!parent) |
| parent = root_mem_cgroup; |
| |
| memcg_reparent_list_lrus(memcg, parent); |
| |
| /* |
| * Objcg's reparenting must be after list_lru's, make sure list_lru |
| * helpers won't use parent's list_lru until child is drained. |
| */ |
| memcg_reparent_objcgs(memcg, parent); |
| } |
| |
| #ifdef CONFIG_CGROUP_WRITEBACK |
| |
| #include <trace/events/writeback.h> |
| |
| static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) |
| { |
| return wb_domain_init(&memcg->cgwb_domain, gfp); |
| } |
| |
| static void memcg_wb_domain_exit(struct mem_cgroup *memcg) |
| { |
| wb_domain_exit(&memcg->cgwb_domain); |
| } |
| |
| static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg) |
| { |
| wb_domain_size_changed(&memcg->cgwb_domain); |
| } |
| |
| struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb) |
| { |
| struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); |
| |
| if (!memcg->css.parent) |
| return NULL; |
| |
| return &memcg->cgwb_domain; |
| } |
| |
| /** |
| * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg |
| * @wb: bdi_writeback in question |
| * @pfilepages: out parameter for number of file pages |
| * @pheadroom: out parameter for number of allocatable pages according to memcg |
| * @pdirty: out parameter for number of dirty pages |
| * @pwriteback: out parameter for number of pages under writeback |
| * |
| * Determine the numbers of file, headroom, dirty, and writeback pages in |
| * @wb's memcg. File, dirty and writeback are self-explanatory. Headroom |
| * is a bit more involved. |
| * |
| * A memcg's headroom is "min(max, high) - used". In the hierarchy, the |
| * headroom is calculated as the lowest headroom of itself and the |
| * ancestors. Note that this doesn't consider the actual amount of |
| * available memory in the system. The caller should further cap |
| * *@pheadroom accordingly. |
| */ |
| void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages, |
| unsigned long *pheadroom, unsigned long *pdirty, |
| unsigned long *pwriteback) |
| { |
| struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); |
| struct mem_cgroup *parent; |
| |
| mem_cgroup_flush_stats_ratelimited(memcg); |
| |
| *pdirty = memcg_page_state(memcg, NR_FILE_DIRTY); |
| *pwriteback = memcg_page_state(memcg, NR_WRITEBACK); |
| *pfilepages = memcg_page_state(memcg, NR_INACTIVE_FILE) + |
| memcg_page_state(memcg, NR_ACTIVE_FILE); |
| |
| *pheadroom = PAGE_COUNTER_MAX; |
| while ((parent = parent_mem_cgroup(memcg))) { |
| unsigned long ceiling = min(READ_ONCE(memcg->memory.max), |
| READ_ONCE(memcg->memory.high)); |
| unsigned long used = page_counter_read(&memcg->memory); |
| |
| *pheadroom = min(*pheadroom, ceiling - min(ceiling, used)); |
| memcg = parent; |
| } |
| } |
| |
| /* |
| * Foreign dirty flushing |
| * |
| * There's an inherent mismatch between memcg and writeback. The former |
| * tracks ownership per-page while the latter per-inode. This was a |
| * deliberate design decision because honoring per-page ownership in the |
| * writeback path is complicated, may lead to higher CPU and IO overheads |
| * and deemed unnecessary given that write-sharing an inode across |
| * different cgroups isn't a common use-case. |
| * |
| * Combined with inode majority-writer ownership switching, this works well |
| * enough in most cases but there are some pathological cases. For |
| * example, let's say there are two cgroups A and B which keep writing to |
| * different but confined parts of the same inode. B owns the inode and |
| * A's memory is limited far below B's. A's dirty ratio can rise enough to |
| * trigger balance_dirty_pages() sleeps but B's can be low enough to avoid |
| * triggering background writeback. A will be slowed down without a way to |
| * make writeback of the dirty pages happen. |
| * |
| * Conditions like the above can lead to a cgroup getting repeatedly and |
| * severely throttled after making some progress after each |
| * dirty_expire_interval while the underlying IO device is almost |
| * completely idle. |
| * |
| * Solving this problem completely requires matching the ownership tracking |
| * granularities between memcg and writeback in either direction. However, |
| * the more egregious behaviors can be avoided by simply remembering the |
| * most recent foreign dirtying events and initiating remote flushes on |
| * them when local writeback isn't enough to keep the memory clean enough. |
| * |
| * The following two functions implement such mechanism. When a foreign |
| * page - a page whose memcg and writeback ownerships don't match - is |
| * dirtied, mem_cgroup_track_foreign_dirty() records the inode owning |
| * bdi_writeback on the page owning memcg. When balance_dirty_pages() |
| * decides that the memcg needs to sleep due to high dirty ratio, it calls |
| * mem_cgroup_flush_foreign() which queues writeback on the recorded |
| * foreign bdi_writebacks which haven't expired. Both the numbers of |
| * recorded bdi_writebacks and concurrent in-flight foreign writebacks are |
| * limited to MEMCG_CGWB_FRN_CNT. |
| * |
| * The mechanism only remembers IDs and doesn't hold any object references. |
| * As being wrong occasionally doesn't matter, updates and accesses to the |
| * records are lockless and racy. |
| */ |
| void mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio, |
| struct bdi_writeback *wb) |
| { |
| struct mem_cgroup *memcg = folio_memcg(folio); |
| struct memcg_cgwb_frn *frn; |
| u64 now = get_jiffies_64(); |
| u64 oldest_at = now; |
| int oldest = -1; |
| int i; |
| |
| trace_track_foreign_dirty(folio, wb); |
| |
| /* |
| * Pick the slot to use. If there is already a slot for @wb, keep |
| * using it. If not replace the oldest one which isn't being |
| * written out. |
| */ |
| for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) { |
| frn = &memcg->cgwb_frn[i]; |
| if (frn->bdi_id == wb->bdi->id && |
| frn->memcg_id == wb->memcg_css->id) |
| break; |
| if (time_before64(frn->at, oldest_at) && |
| atomic_read(&frn->done.cnt) == 1) { |
| oldest = i; |
| oldest_at = frn->at; |
| } |
| } |
| |
| if (i < MEMCG_CGWB_FRN_CNT) { |
| /* |
| * Re-using an existing one. Update timestamp lazily to |
| * avoid making the cacheline hot. We want them to be |
| * reasonably up-to-date and significantly shorter than |
| * dirty_expire_interval as that's what expires the record. |
| * Use the shorter of 1s and dirty_expire_interval / 8. |
| */ |
| unsigned long update_intv = |
| min_t(unsigned long, HZ, |
| msecs_to_jiffies(dirty_expire_interval * 10) / 8); |
| |
| if (time_before64(frn->at, now - update_intv)) |
| frn->at = now; |
| } else if (oldest >= 0) { |
| /* replace the oldest free one */ |
| frn = &memcg->cgwb_frn[oldest]; |
| frn->bdi_id = wb->bdi->id; |
| frn->memcg_id = wb->memcg_css->id; |
| frn->at = now; |
| } |
| } |
| |
| /* issue foreign writeback flushes for recorded foreign dirtying events */ |
| void mem_cgroup_flush_foreign(struct bdi_writeback *wb) |
| { |
| struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); |
| unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10); |
| u64 now = jiffies_64; |
| int i; |
| |
| for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) { |
| struct memcg_cgwb_frn *frn = &memcg->cgwb_frn[i]; |
| |
| /* |
| * If the record is older than dirty_expire_interval, |
| * writeback on it has already started. No need to kick it |
| * off again. Also, don't start a new one if there's |
| * already one in flight. |
| */ |
| if (time_after64(frn->at, now - intv) && |
| atomic_read(&frn->done.cnt) == 1) { |
| frn->at = 0; |
| trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id); |
| cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id, |
| WB_REASON_FOREIGN_FLUSH, |
| &frn->done); |
| } |
| } |
| } |
| |
| #else /* CONFIG_CGROUP_WRITEBACK */ |
| |
| static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp) |
| { |
| return 0; |
| } |
| |
| static void memcg_wb_domain_exit(struct mem_cgroup *memcg) |
| { |
| } |
| |
| static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg) |
| { |
| } |
| |
| #endif /* CONFIG_CGROUP_WRITEBACK */ |
| |
| /* |
| * Private memory cgroup IDR |
| * |
| * Swap-out records and page cache shadow entries need to store memcg |
| * references in constrained space, so we maintain an ID space that is |
| * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of |
| * memory-controlled cgroups to 64k. |
| * |
| * However, there usually are many references to the offline CSS after |
| * the cgroup has been destroyed, such as page cache or reclaimable |
| * slab objects, that don't need to hang on to the ID. We want to keep |
| * those dead CSS from occupying IDs, or we might quickly exhaust the |
| * relatively small ID space and prevent the creation of new cgroups |
| * even when there are much fewer than 64k cgroups - possibly none. |
| * |
| * Maintain a private 16-bit ID space for memcg, and allow the ID to |
| * be freed and recycled when it's no longer needed, which is usually |
| * when the CSS is offlined. |
| * |
| * The only exception to that are re
|