To gather all direct accesses to struct page's memcg_data field in one place, let's introduce 4 new helper functions to use in the slab accounting code: struct obj_cgroup **page_obj_cgroups(struct page *page); struct obj_cgroup **page_obj_cgroups_check(struct page *page); bool set_page_obj_cgroups(struct page *page, struct obj_cgroup **objcgs); void clear_page_obj_cgroups(struct page *page);
They are similar to the corresponding API for generic pages, except that the setter can return false, indicating that the value has been already set from a different thread. Signed-off-by: Roman Gushchin <[email protected]> --- include/linux/memcontrol.h | 48 ++++++++++++++++++++++++++++++++++++++ mm/memcontrol.c | 4 ++-- mm/slab.h | 27 +++------------------ 3 files changed, 53 insertions(+), 26 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 0997220c84ce..48d4c2c1ce81 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -375,6 +375,54 @@ static inline void clear_page_mem_cgroup(struct page *page) page->memcg_data = 0; } +#ifdef CONFIG_MEMCG_KMEM +static inline struct obj_cgroup **page_obj_cgroups(struct page *page) +{ + return (struct obj_cgroup **)(page->memcg_data & ~0x1UL); +} + +static inline struct obj_cgroup **page_obj_cgroups_check(struct page *page) +{ + unsigned long memcg_data = page->memcg_data; + + if (memcg_data && (memcg_data & 0x1UL)) + return (struct obj_cgroup **)memcg_data; + + return NULL; +} + +static inline bool set_page_obj_cgroups(struct page *page, + struct obj_cgroup **objcgs) +{ + return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL); +} + +static inline void clear_page_obj_cgroups(struct page *page) +{ + page->memcg_data = 0; +} +#else +static inline struct obj_cgroup **page_obj_cgroups(struct page *page) +{ + return NULL; +} + +static inline struct obj_cgroup **page_obj_cgroups_check(struct page *page) +{ + return NULL; +} + +static inline bool set_page_obj_cgroups(struct page *page, + struct obj_cgroup **objcgs) +{ + return true; +} + +static inline void clear_page_obj_cgroups(struct page *page) +{ +} +#endif + static __always_inline bool memcg_stat_item_in_bytes(int idx) { if (idx == MEMCG_PERCPU_B) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 19180674e38a..ba9b053b1b88 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2890,7 +2890,7 @@ int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s, if (!vec) return -ENOMEM; - if (cmpxchg(&page->memcg_data, 0, (unsigned long)vec | 0x1UL)) + if (!set_page_obj_cgroups(page, vec)) kfree(vec); else kmemleak_not_leak(vec); @@ -2918,7 +2918,7 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p) * Memcg membership data for each individual object is saved in * the page->obj_cgroups. */ - if (page_has_obj_cgroups(page)) { + if (page_obj_cgroups_check(page)) { struct obj_cgroup *objcg; unsigned int off; diff --git a/mm/slab.h b/mm/slab.h index b9787c4d6e78..9a46ab76cb61 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -239,29 +239,13 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla } #ifdef CONFIG_MEMCG_KMEM -static inline struct obj_cgroup **page_obj_cgroups(struct page *page) -{ - /* - * page->mem_cgroup and page->obj_cgroups are sharing the same - * space. To distinguish between them in case we don't know for sure - * that the page is a slab page (e.g. page_cgroup_ino()), let's - * always set the lowest bit of obj_cgroups. - */ - return (struct obj_cgroup **)(page->memcg_data & ~0x1UL); -} - -static inline bool page_has_obj_cgroups(struct page *page) -{ - return page->memcg_data & 0x1UL; -} - 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) { kfree(page_obj_cgroups(page)); - page->memcg_data = 0; + clear_page_obj_cgroups(page); } static inline size_t obj_full_size(struct kmem_cache *s) @@ -322,7 +306,7 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, if (likely(p[i])) { page = virt_to_head_page(p[i]); - if (!page_has_obj_cgroups(page) && + if (!page_obj_cgroups(page) && memcg_alloc_page_obj_cgroups(page, s, flags)) { obj_cgroup_uncharge(objcg, obj_full_size(s)); continue; @@ -349,7 +333,7 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, if (!memcg_kmem_enabled()) return; - if (!page_has_obj_cgroups(page)) + if (!page_obj_cgroups(page)) return; off = obj_to_index(s, page, p); @@ -367,11 +351,6 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, } #else /* CONFIG_MEMCG_KMEM */ -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; -- 2.26.2
