From 9855609bde03e2472b99a95e869d29ee1e78a751 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 6 Aug 2020 23:21:10 -0700 Subject: mm: memcg/slab: use a single set of kmem_caches for all accounted allocations This is fairly big but mostly red patch, which makes all accounted slab allocations use a single set of kmem_caches instead of creating a separate set for each memory cgroup. Because the number of non-root kmem_caches is now capped by the number of root kmem_caches, there is no need to shrink or destroy them prematurely. They can be perfectly destroyed together with their root counterparts. This allows to dramatically simplify the management of non-root kmem_caches and delete a ton of code. This patch performs the following changes: 1) introduces memcg_params.memcg_cache pointer to represent the kmem_cache which will be used for all non-root allocations 2) reuses the existing memcg kmem_cache creation mechanism to create memcg kmem_cache on the first allocation attempt 3) memcg kmem_caches are named -memcg, e.g. dentry-memcg 4) simplifies memcg_kmem_get_cache() to just return memcg kmem_cache or schedule it's creation and return the root cache 5) removes almost all non-root kmem_cache management code (separate refcounter, reparenting, shrinking, etc) 6) makes slab debugfs to display root_mem_cgroup css id and never show :dead and :deact flags in the memcg_slabinfo attribute. Following patches in the series will simplify the kmem_cache creation. Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Link: http://lkml.kernel.org/r/20200623174037.3951353-13-guro@fb.com Signed-off-by: Linus Torvalds --- mm/slab.h | 146 +++++++++++++++++++------------------------------------------- 1 file changed, 45 insertions(+), 101 deletions(-) (limited to 'mm/slab.h') diff --git a/mm/slab.h b/mm/slab.h index 1f067e8bc377..e716b80befc2 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -32,66 +32,25 @@ struct kmem_cache { #else /* !CONFIG_SLOB */ -struct memcg_cache_array { - struct rcu_head rcu; - struct kmem_cache *entries[0]; -}; - /* * This is the main placeholder for memcg-related information in kmem caches. - * Both the root cache and the child caches will have it. For the root cache, - * this will hold a dynamically allocated array large enough to hold - * information about the currently limited memcgs in the system. To allow the - * array to be accessed without taking any locks, on relocation we free the old - * version only after a grace period. - * - * Root and child caches hold different metadata. + * Both the root cache and the child cache will have it. Some fields are used + * in both cases, other are specific to root caches. * * @root_cache: Common to root and child caches. NULL for root, pointer to * the root cache for children. * * The following fields are specific to root caches. * - * @memcg_caches: kmemcg ID indexed table of child caches. This table is - * used to index child cachces during allocation and cleared - * early during shutdown. - * - * @root_caches_node: List node for slab_root_caches list. - * - * @children: List of all child caches. While the child caches are also - * reachable through @memcg_caches, a child cache remains on - * this list until it is actually destroyed. - * - * The following fields are specific to child caches. - * - * @memcg: Pointer to the memcg this cache belongs to. - * - * @children_node: List node for @root_cache->children list. - * - * @kmem_caches_node: List node for @memcg->kmem_caches list. + * @memcg_cache: pointer to memcg kmem cache, used by all non-root memory + * cgroups. + * @root_caches_node: list node for slab_root_caches list. */ struct memcg_cache_params { struct kmem_cache *root_cache; - union { - struct { - struct memcg_cache_array __rcu *memcg_caches; - struct list_head __root_caches_node; - struct list_head children; - bool dying; - }; - struct { - struct mem_cgroup *memcg; - struct list_head children_node; - struct list_head kmem_caches_node; - struct percpu_ref refcnt; - - void (*work_fn)(struct kmem_cache *); - union { - struct rcu_head rcu_head; - struct work_struct work; - }; - }; - }; + + struct kmem_cache *memcg_cache; + struct list_head __root_caches_node; }; #endif /* CONFIG_SLOB */ @@ -236,8 +195,6 @@ bool __kmem_cache_empty(struct kmem_cache *); int __kmem_cache_shutdown(struct kmem_cache *); void __kmem_cache_release(struct kmem_cache *); int __kmem_cache_shrink(struct kmem_cache *); -void __kmemcg_cache_deactivate(struct kmem_cache *s); -void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s); void slab_kmem_cache_release(struct kmem_cache *); void kmem_cache_shrink_all(struct kmem_cache *s); @@ -311,14 +268,6 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla extern struct list_head slab_root_caches; #define root_caches_node memcg_params.__root_caches_node -/* - * Iterate over all memcg caches of the given root cache. The caller must hold - * slab_mutex. - */ -#define for_each_memcg_cache(iter, root) \ - list_for_each_entry(iter, &(root)->memcg_params.children, \ - memcg_params.children_node) - static inline bool is_root_cache(struct kmem_cache *s) { return !s->memcg_params.root_cache; @@ -349,6 +298,13 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) return s->memcg_params.root_cache; } +static inline struct kmem_cache *memcg_cache(struct kmem_cache *s) +{ + if (is_root_cache(s)) + return s->memcg_params.memcg_cache; + return NULL; +} + static inline struct obj_cgroup **page_obj_cgroups(struct page *page) { /* @@ -361,25 +317,9 @@ static inline struct obj_cgroup **page_obj_cgroups(struct page *page) ((unsigned long)page->obj_cgroups & ~0x1UL); } -/* - * Expects a pointer to a slab page. Please note, that PageSlab() check - * isn't sufficient, as it returns true also for tail compound slab pages, - * which do not have slab_cache pointer set. - * So this function assumes that the page can pass PageSlab() && !PageTail() - * check. - * - * The kmem_cache can be reparented asynchronously. The caller must ensure - * the memcg lifetime, e.g. by taking rcu_read_lock() or cgroup_mutex. - */ -static inline struct mem_cgroup *memcg_from_slab_page(struct page *page) +static inline bool page_has_obj_cgroups(struct page *page) { - struct kmem_cache *s; - - s = READ_ONCE(page->slab_cache); - if (s && !is_root_cache(s)) - return READ_ONCE(s->memcg_params.memcg); - - return NULL; + return ((unsigned long)page->obj_cgroups & 0x1UL); } static inline int memcg_alloc_page_obj_cgroups(struct page *page, @@ -418,17 +358,25 @@ static inline struct kmem_cache *memcg_slab_pre_alloc_hook(struct kmem_cache *s, size_t objects, gfp_t flags) { struct kmem_cache *cachep; + struct obj_cgroup *objcg; + + if (memcg_kmem_bypass()) + return s; - cachep = memcg_kmem_get_cache(s, objcgp); + cachep = memcg_kmem_get_cache(s); if (is_root_cache(cachep)) return s; - if (obj_cgroup_charge(*objcgp, flags, objects * obj_full_size(s))) { - obj_cgroup_put(*objcgp); - memcg_kmem_put_cache(cachep); + objcg = get_obj_cgroup_from_current(); + if (!objcg) + return s; + + if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) { + obj_cgroup_put(objcg); cachep = NULL; } + *objcgp = objcg; return cachep; } @@ -467,7 +415,6 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, } } obj_cgroup_put(objcg); - memcg_kmem_put_cache(s); } static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, @@ -491,7 +438,7 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, } extern void slab_init_memcg_params(struct kmem_cache *); -extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg); +extern void memcg_link_cache(struct kmem_cache *s); #else /* CONFIG_MEMCG_KMEM */ @@ -499,9 +446,6 @@ extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg); #define slab_root_caches slab_caches #define root_caches_node list -#define for_each_memcg_cache(iter, root) \ - for ((void)(iter), (void)(root); 0; ) - static inline bool is_root_cache(struct kmem_cache *s) { return true; @@ -523,7 +467,17 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) return s; } -static inline struct mem_cgroup *memcg_from_slab_page(struct page *page) +static inline struct kmem_cache *memcg_cache(struct kmem_cache *s) +{ + return NULL; +} + +static inline bool page_has_obj_cgroups(struct page *page) +{ + return false; +} + +static inline struct mem_cgroup *memcg_from_slab_obj(void *ptr) { return NULL; } @@ -560,8 +514,7 @@ static inline void slab_init_memcg_params(struct kmem_cache *s) { } -static inline void memcg_link_cache(struct kmem_cache *s, - struct mem_cgroup *memcg) +static inline void memcg_link_cache(struct kmem_cache *s) { } @@ -582,17 +535,14 @@ static __always_inline int charge_slab_page(struct page *page, gfp_t gfp, int order, struct kmem_cache *s) { -#ifdef CONFIG_MEMCG_KMEM if (memcg_kmem_enabled() && !is_root_cache(s)) { int ret; ret = memcg_alloc_page_obj_cgroups(page, s, gfp); if (ret) return ret; - - percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order); } -#endif + mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), PAGE_SIZE << order); return 0; @@ -601,12 +551,9 @@ static __always_inline int charge_slab_page(struct page *page, static __always_inline void uncharge_slab_page(struct page *page, int order, struct kmem_cache *s) { -#ifdef CONFIG_MEMCG_KMEM - if (memcg_kmem_enabled() && !is_root_cache(s)) { + if (memcg_kmem_enabled() && !is_root_cache(s)) memcg_free_page_obj_cgroups(page); - percpu_ref_put_many(&s->memcg_params.refcnt, 1 << order); - } -#endif + mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), -(PAGE_SIZE << order)); } @@ -749,9 +696,6 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node) void *slab_start(struct seq_file *m, loff_t *pos); void *slab_next(struct seq_file *m, void *p, loff_t *pos); void slab_stop(struct seq_file *m, void *p); -void *memcg_slab_start(struct seq_file *m, loff_t *pos); -void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos); -void memcg_slab_stop(struct seq_file *m, void *p); int memcg_slab_show(struct seq_file *m, void *p); #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) -- cgit v1.2.3