From 10befea91b61c4e2c2d1df06a2e978d182fcf792 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 6 Aug 2020 23:21:27 -0700 Subject: mm: memcg/slab: use a single set of kmem_caches for all allocations Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Michal Hocko Cc: Tejun Heo Cc: Naresh Kamboju Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds --- mm/slab.h | 194 ++++++++++++++------------------------------------------------ 1 file changed, 42 insertions(+), 152 deletions(-) (limited to 'mm/slab.h') diff --git a/mm/slab.h b/mm/slab.h index 7500a707121b..ec8e22ee6544 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -30,28 +30,6 @@ struct kmem_cache { struct list_head list; /* List of all slab caches on the system */ }; -#else /* !CONFIG_SLOB */ - -/* - * This is the main placeholder for memcg-related information in kmem caches. - * 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_cache: pointer to memcg kmem cache, used by all non-root memory - * cgroups. - * @work: work struct used to create the non-root cache. - */ -struct memcg_cache_params { - struct kmem_cache *root_cache; - - struct kmem_cache *memcg_cache; - struct work_struct work; -}; #endif /* CONFIG_SLOB */ #ifdef CONFIG_SLAB @@ -196,7 +174,6 @@ int __kmem_cache_shutdown(struct kmem_cache *); void __kmem_cache_release(struct kmem_cache *); int __kmem_cache_shrink(struct kmem_cache *); void slab_kmem_cache_release(struct kmem_cache *); -void kmem_cache_shrink_all(struct kmem_cache *s); struct seq_file; struct file; @@ -263,43 +240,6 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla } #ifdef CONFIG_MEMCG_KMEM -static inline bool is_root_cache(struct kmem_cache *s) -{ - return !s->memcg_params.root_cache; -} - -static inline bool slab_equal_or_root(struct kmem_cache *s, - struct kmem_cache *p) -{ - return p == s || p == s->memcg_params.root_cache; -} - -/* - * We use suffixes to the name in memcg because we can't have caches - * created in the system with the same name. But when we print them - * locally, better refer to them with the base name - */ -static inline const char *cache_name(struct kmem_cache *s) -{ - if (!is_root_cache(s)) - s = s->memcg_params.root_cache; - return s->name; -} - -static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) -{ - if (is_root_cache(s)) - return 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) { /* @@ -317,21 +257,8 @@ static inline bool page_has_obj_cgroups(struct page *page) return ((unsigned long)page->obj_cgroups & 0x1UL); } -static inline int memcg_alloc_page_obj_cgroups(struct page *page, - struct kmem_cache *s, gfp_t gfp) -{ - unsigned int objects = objs_per_slab_page(s, page); - void *vec; - - vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp, - page_to_nid(page)); - if (!vec) - return -ENOMEM; - - kmemleak_not_leak(vec); - page->obj_cgroups = (struct obj_cgroup **) ((unsigned long)vec | 0x1UL); - return 0; -} +int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s, + gfp_t gfp); static inline void memcg_free_page_obj_cgroups(struct page *page) { @@ -348,38 +275,25 @@ static inline size_t obj_full_size(struct kmem_cache *s) return s->size + sizeof(struct obj_cgroup *); } -static inline struct kmem_cache *memcg_slab_pre_alloc_hook(struct kmem_cache *s, - struct obj_cgroup **objcgp, - size_t objects, gfp_t flags) +static inline struct obj_cgroup *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 = READ_ONCE(s->memcg_params.memcg_cache); - if (unlikely(!cachep)) { - /* - * If memcg cache does not exist yet, we schedule it's - * asynchronous creation and let the current allocation - * go through with the root cache. - */ - queue_work(system_wq, &s->memcg_params.work); - return s; - } + return NULL; objcg = get_obj_cgroup_from_current(); if (!objcg) - return s; + return NULL; if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) { obj_cgroup_put(objcg); - cachep = NULL; + return NULL; } - *objcgp = objcg; - return cachep; + return objcg; } static inline void mod_objcg_state(struct obj_cgroup *objcg, @@ -398,15 +312,27 @@ static inline void mod_objcg_state(struct obj_cgroup *objcg, static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, - size_t size, void **p) + gfp_t flags, size_t size, + void **p) { struct page *page; unsigned long off; size_t i; + if (!objcg) + return; + + flags &= ~__GFP_ACCOUNT; for (i = 0; i < size; i++) { if (likely(p[i])) { page = virt_to_head_page(p[i]); + + if (!page_has_obj_cgroups(page) && + memcg_alloc_page_obj_cgroups(page, s, flags)) { + obj_cgroup_uncharge(objcg, obj_full_size(s)); + continue; + } + off = obj_to_index(s, page, p[i]); obj_cgroup_get(objcg); page_obj_cgroups(page)[off] = objcg; @@ -425,13 +351,19 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, struct obj_cgroup *objcg; unsigned int off; - if (!memcg_kmem_enabled() || is_root_cache(s)) + if (!memcg_kmem_enabled()) + return; + + if (!page_has_obj_cgroups(page)) return; off = obj_to_index(s, page, p); objcg = page_obj_cgroups(page)[off]; page_obj_cgroups(page)[off] = NULL; + if (!objcg) + return; + obj_cgroup_uncharge(objcg, obj_full_size(s)); mod_objcg_state(objcg, page_pgdat(page), cache_vmstat_idx(s), -obj_full_size(s)); @@ -439,35 +371,7 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, obj_cgroup_put(objcg); } -extern void slab_init_memcg_params(struct kmem_cache *); - #else /* CONFIG_MEMCG_KMEM */ -static inline bool is_root_cache(struct kmem_cache *s) -{ - return true; -} - -static inline bool slab_equal_or_root(struct kmem_cache *s, - struct kmem_cache *p) -{ - return s == p; -} - -static inline const char *cache_name(struct kmem_cache *s) -{ - return s->name; -} - -static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) -{ - return s; -} - -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; @@ -488,16 +392,17 @@ static inline void memcg_free_page_obj_cgroups(struct page *page) { } -static inline struct kmem_cache *memcg_slab_pre_alloc_hook(struct kmem_cache *s, - struct obj_cgroup **objcgp, - size_t objects, gfp_t flags) +static inline struct obj_cgroup *memcg_slab_pre_alloc_hook(struct kmem_cache *s, + size_t objects, + gfp_t flags) { return NULL; } static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, - size_t size, void **p) + gfp_t flags, size_t size, + void **p) { } @@ -505,11 +410,6 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, void *p) { } - -static inline void slab_init_memcg_params(struct kmem_cache *s) -{ -} - #endif /* CONFIG_MEMCG_KMEM */ static inline struct kmem_cache *virt_to_cache(const void *obj) @@ -523,27 +423,18 @@ static inline struct kmem_cache *virt_to_cache(const void *obj) return page->slab_cache; } -static __always_inline int charge_slab_page(struct page *page, - gfp_t gfp, int order, - struct kmem_cache *s) +static __always_inline void charge_slab_page(struct page *page, + gfp_t gfp, int order, + struct kmem_cache *s) { - if (memcg_kmem_enabled() && !is_root_cache(s)) { - int ret; - - ret = memcg_alloc_page_obj_cgroups(page, s, gfp); - if (ret) - return ret; - } - mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), PAGE_SIZE << order); - return 0; } static __always_inline void uncharge_slab_page(struct page *page, int order, struct kmem_cache *s) { - if (memcg_kmem_enabled() && !is_root_cache(s)) + if (memcg_kmem_enabled()) memcg_free_page_obj_cgroups(page); mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), @@ -555,12 +446,11 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x) struct kmem_cache *cachep; if (!IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) && - !memcg_kmem_enabled() && !kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) return s; cachep = virt_to_cache(x); - if (WARN(cachep && !slab_equal_or_root(cachep, s), + if (WARN(cachep && cachep != s, "%s: Wrong slab cache. %s but object is from %s\n", __func__, s->name, cachep->name)) print_tracking(cachep, x); @@ -613,7 +503,7 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, if (memcg_kmem_enabled() && ((flags & __GFP_ACCOUNT) || (s->flags & SLAB_ACCOUNT))) - return memcg_slab_pre_alloc_hook(s, objcgp, size, flags); + *objcgp = memcg_slab_pre_alloc_hook(s, size, flags); return s; } @@ -632,8 +522,8 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, s->flags, flags); } - if (memcg_kmem_enabled() && !is_root_cache(s)) - memcg_slab_post_alloc_hook(s, objcg, size, p); + if (memcg_kmem_enabled()) + memcg_slab_post_alloc_hook(s, objcg, flags, size, p); } #ifndef CONFIG_SLOB -- cgit