diff options
| -rw-r--r-- | include/linux/memcontrol.h | 51 | ||||
| -rw-r--r-- | mm/memcontrol.c | 288 |
2 files changed, 338 insertions, 1 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index b250f8197710..f2f9d5d6b7d1 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -23,6 +23,7 @@ #include <linux/page-flags.h> struct mem_cgroup; +struct obj_cgroup; struct page; struct mm_struct; struct kmem_cache; @@ -193,6 +194,22 @@ struct memcg_cgwb_frn { }; /* + * Bucket for arbitrarily byte-sized objects charged to a memory + * cgroup. The bucket can be reparented in one piece when the cgroup + * is destroyed, without having to round up the individual references + * of all live memory objects in the wild. + */ +struct obj_cgroup { + struct percpu_ref refcnt; + struct mem_cgroup *memcg; + atomic_t nr_charged_bytes; + union { + struct list_head list; + struct rcu_head rcu; + }; +}; + +/* * The memory controller data structure. The memory controller controls both * page cache and RSS per cgroup. We would eventually like to provide * statistics based on the statistics developed by Rik Van Riel for clock-pro, @@ -301,6 +318,8 @@ struct mem_cgroup { int kmemcg_id; enum memcg_kmem_state kmem_state; struct list_head kmem_caches; + struct obj_cgroup __rcu *objcg; + struct list_head objcg_list; /* list of inherited objcgs */ #endif #ifdef CONFIG_CGROUP_WRITEBACK @@ -416,6 +435,33 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){ return css ? container_of(css, struct mem_cgroup, css) : NULL; } +static inline bool obj_cgroup_tryget(struct obj_cgroup *objcg) +{ + return percpu_ref_tryget(&objcg->refcnt); +} + +static inline void obj_cgroup_get(struct obj_cgroup *objcg) +{ + percpu_ref_get(&objcg->refcnt); +} + +static inline void obj_cgroup_put(struct obj_cgroup *objcg) +{ + percpu_ref_put(&objcg->refcnt); +} + +/* + * After the initialization objcg->memcg is always pointing at + * a valid memcg, but can be atomically swapped to the parent memcg. + * + * The caller must ensure that the returned memcg won't be released: + * e.g. acquire the rcu_read_lock or css_set_lock. + */ +static inline struct mem_cgroup *obj_cgroup_memcg(struct obj_cgroup *objcg) +{ + return READ_ONCE(objcg->memcg); +} + static inline void mem_cgroup_put(struct mem_cgroup *memcg) { if (memcg) @@ -1368,6 +1414,11 @@ void __memcg_kmem_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages); int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order); void __memcg_kmem_uncharge_page(struct page *page, int order); +struct obj_cgroup *get_obj_cgroup_from_current(void); + +int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size); +void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size); + extern struct static_key_false memcg_kmem_enabled_key; extern struct workqueue_struct *memcg_kmem_cache_wq; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4f9a3f55db71..1cc784556e05 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -257,6 +257,98 @@ struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr) } #ifdef CONFIG_MEMCG_KMEM +extern spinlock_t css_set_lock; + +static void obj_cgroup_release(struct percpu_ref *ref) +{ + struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt); + struct mem_cgroup *memcg; + 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; + + spin_lock_irqsave(&css_set_lock, flags); + memcg = obj_cgroup_memcg(objcg); + if (nr_pages) + __memcg_kmem_uncharge(memcg, nr_pages); + list_del(&objcg->list); + mem_cgroup_put(memcg); + spin_unlock_irqrestore(&css_set_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(&css_set_lock); + + /* Move active objcg to the parent's list */ + xchg(&objcg->memcg, parent); + css_get(&parent->css); + list_add(&objcg->list, &parent->objcg_list); + + /* Move already reparented objcgs to the parent's list */ + list_for_each_entry(iter, &memcg->objcg_list, list) { + css_get(&parent->css); + xchg(&iter->memcg, parent); + css_put(&memcg->css); + } + list_splice(&memcg->objcg_list, &parent->objcg_list); + + spin_unlock_irq(&css_set_lock); + + percpu_ref_kill(&objcg->refcnt); +} + /* * This will be the memcg's index in each cache's ->memcg_params.memcg_caches. * The main reason for not using cgroup id for this: @@ -2047,6 +2139,12 @@ EXPORT_SYMBOL(unlock_page_memcg); struct memcg_stock_pcp { struct mem_cgroup *cached; /* this never be root cgroup */ unsigned int nr_pages; + +#ifdef CONFIG_MEMCG_KMEM + struct obj_cgroup *cached_objcg; + unsigned int nr_bytes; +#endif + struct work_struct work; unsigned long flags; #define FLUSHING_CACHED_CHARGE 0 @@ -2054,6 +2152,22 @@ struct memcg_stock_pcp { static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); static DEFINE_MUTEX(percpu_charge_mutex); +#ifdef CONFIG_MEMCG_KMEM +static void drain_obj_stock(struct memcg_stock_pcp *stock); +static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, + struct mem_cgroup *root_memcg); + +#else +static inline void drain_obj_stock(struct memcg_stock_pcp *stock) +{ +} +static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, + struct mem_cgroup *root_memcg) +{ + return false; +} +#endif + /** * consume_stock: Try to consume stocked charge on this cpu. * @memcg: memcg to consume from. @@ -2120,6 +2234,7 @@ static void drain_local_stock(struct work_struct *dummy) local_irq_save(flags); stock = this_cpu_ptr(&memcg_stock); + drain_obj_stock(stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); @@ -2179,6 +2294,8 @@ static void drain_all_stock(struct mem_cgroup *root_memcg) if (memcg && stock->nr_pages && mem_cgroup_is_descendant(memcg, root_memcg)) flush = true; + if (obj_stock_flush_required(stock, root_memcg)) + flush = true; rcu_read_unlock(); if (flush && @@ -2705,6 +2822,30 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p) return page->mem_cgroup; } +__always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) +{ + struct obj_cgroup *objcg = NULL; + struct mem_cgroup *memcg; + + if (unlikely(!current->mm && !current->active_memcg)) + return NULL; + + rcu_read_lock(); + if (unlikely(current->active_memcg)) + memcg = rcu_dereference(current->active_memcg); + else + memcg = mem_cgroup_from_task(current); + + for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) { + objcg = rcu_dereference(memcg->objcg); + if (objcg && obj_cgroup_tryget(objcg)) + break; + } + rcu_read_unlock(); + + return objcg; +} + static int memcg_alloc_cache_id(void) { int id, size; @@ -2996,6 +3137,140 @@ void __memcg_kmem_uncharge_page(struct page *page, int order) if (PageKmemcg(page)) __ClearPageKmemcg(page); } + +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_irq_save(flags); + + stock = this_cpu_ptr(&memcg_stock); + if (objcg == stock->cached_objcg && stock->nr_bytes >= nr_bytes) { + stock->nr_bytes -= nr_bytes; + ret = true; + } + + local_irq_restore(flags); + + return ret; +} + +static void drain_obj_stock(struct memcg_stock_pcp *stock) +{ + struct obj_cgroup *old = stock->cached_objcg; + + if (!old) + return; + + if (stock->nr_bytes) { + unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT; + unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1); + + if (nr_pages) { + rcu_read_lock(); + __memcg_kmem_uncharge(obj_cgroup_memcg(old), nr_pages); + rcu_read_unlock(); + } + + /* + * 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; + } + + obj_cgroup_put(old); + stock->cached_objcg = NULL; +} + +static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, + struct mem_cgroup *root_memcg) +{ + struct mem_cgroup *memcg; + + if (stock->cached_objcg) { + memcg = obj_cgroup_memcg(stock->cached_objcg); + if (memcg && mem_cgroup_is_descendant(memcg, root_memcg)) + return true; + } + + return false; +} + +static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) +{ + struct memcg_stock_pcp *stock; + unsigned long flags; + + local_irq_save(flags); + + stock = this_cpu_ptr(&memcg_stock); + if (stock->cached_objcg != objcg) { /* reset if necessary */ + drain_obj_stock(stock); + obj_cgroup_get(objcg); + stock->cached_objcg = objcg; + stock->nr_bytes = atomic_xchg(&objcg->nr_charged_bytes, 0); + } + stock->nr_bytes += nr_bytes; + + if (stock->nr_bytes > PAGE_SIZE) + drain_obj_stock(stock); + + local_irq_restore(flags); +} + +int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size) +{ + struct mem_cgroup *memcg; + unsigned int nr_pages, nr_bytes; + int ret; + + if (consume_obj_stock(objcg, size)) + return 0; + + /* + * In theory, memcg->nr_charged_bytes can have enough + * pre-charged bytes to satisfy the allocation. However, + * flushing memcg->nr_charged_bytes requires two atomic + * operations, and memcg->nr_charged_bytes can't be big, + * so it's better to ignore it and try grab some new pages. + * memcg->nr_charged_bytes will be flushed in + * refill_obj_stock(), called from this function or + * independently later. + */ + rcu_read_lock(); + memcg = obj_cgroup_memcg(objcg); + css_get(&memcg->css); + rcu_read_unlock(); + + nr_pages = size >> PAGE_SHIFT; + nr_bytes = size & (PAGE_SIZE - 1); + + if (nr_bytes) + nr_pages += 1; + + ret = __memcg_kmem_charge(memcg, gfp, nr_pages); + if (!ret && nr_bytes) + refill_obj_stock(objcg, PAGE_SIZE - nr_bytes); + + css_put(&memcg->css); + return ret; +} + +void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size) +{ + refill_obj_stock(objcg, size); +} + #endif /* CONFIG_MEMCG_KMEM */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -3416,6 +3691,7 @@ static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg) #ifdef CONFIG_MEMCG_KMEM static int memcg_online_kmem(struct mem_cgroup *memcg) { + struct obj_cgroup *objcg; int memcg_id; if (cgroup_memory_nokmem) @@ -3428,6 +3704,14 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) if (memcg_id < 0) return memcg_id; + objcg = obj_cgroup_alloc(); + if (!objcg) { + memcg_free_cache_id(memcg_id); + return -ENOMEM; + } + objcg->memcg = memcg; + rcu_assign_pointer(memcg->objcg, objcg); + static_branch_enable(&memcg_kmem_enabled_key); /* @@ -3464,9 +3748,10 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) parent = root_mem_cgroup; /* - * Deactivate and reparent kmem_caches. + * Deactivate and reparent kmem_caches and objcgs. */ memcg_deactivate_kmem_caches(memcg, parent); + memcg_reparent_objcgs(memcg, parent); kmemcg_id = memcg->kmemcg_id; BUG_ON(kmemcg_id < 0); @@ -5030,6 +5315,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) memcg->socket_pressure = jiffies; #ifdef CONFIG_MEMCG_KMEM memcg->kmemcg_id = -1; + INIT_LIST_HEAD(&memcg->objcg_list); #endif #ifdef CONFIG_CGROUP_WRITEBACK INIT_LIST_HEAD(&memcg->cgwb_list); |