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Thu, 24 Sep 2020 12:27:14 -0700 Received: by devvm1755.vll0.facebook.com (Postfix, from userid 111017) id 7086C992379; Thu, 24 Sep 2020 12:27:09 -0700 (PDT) From: Roman Gushchin To: Andrew Morton CC: Shakeel Butt , Johannes Weiner , Michal Hocko , , , , Roman Gushchin Subject: [PATCH v2 2/4] mm: memcontrol/slab: use helpers to access slab page's memcg_data Date: Thu, 24 Sep 2020 12:27:04 -0700 Message-ID: <20200924192706.3075680-3-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200924192706.3075680-1-guro@fb.com> References: <20200924192706.3075680-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-24_14:2020-09-24,2020-09-24 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=811 priorityscore=1501 lowpriorityscore=0 phishscore=0 mlxscore=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 bulkscore=0 spamscore=0 suspectscore=2 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009240140 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.006447, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Reviewed-by: Shakeel Butt --- include/linux/memcontrol.h | 80 ++++++++++++++++++++++++++++++++++++++ mm/memcontrol.c | 4 +- mm/slab.h | 27 ++----------- 3 files changed, 85 insertions(+), 26 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 3313e7c21534..2ed36c8562ac 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -409,6 +409,86 @@ static inline void clear_page_mem_cgroup(struct page *page) page->memcg_data = 0; } +#ifdef CONFIG_MEMCG_KMEM +/* + * page_obj_cgroups - get the object cgroups vector associated with a page + * @page: a pointer to the page struct + * + * Returns a pointer to the object cgroups vector associated with the page, + * or NULL. This function assumes that the page is known to have an + * associated object cgroups vector. It's not safe to call this function + * against pages, which might have an associated memory cgroup: e.g. + * kernel stack pages. + */ +static inline struct obj_cgroup **page_obj_cgroups(struct page *page) +{ + return (struct obj_cgroup **)(page->memcg_data & ~0x1UL); +} + +/* + * page_obj_cgroups_check - get the object cgroups vector associated with a page + * @page: a pointer to the page struct + * + * Returns a pointer to the object cgroups vector associated with the page, + * or NULL. This function is safe to use if the page can be directly associated + * with a memory cgroup. + */ +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 & ~0x1UL); + + return NULL; +} + +/* + * set_page_obj_cgroups - associate a page with a object cgroups vector + * @page: a pointer to the page struct + * @objcgs: a pointer to the object cgroups vector + * + * Atomically associates a page with a vector of object cgroups. + */ +static inline bool set_page_obj_cgroups(struct page *page, + struct obj_cgroup **objcgs) +{ + return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL); +} + +/* + * clear_page_obj_cgroups - clear an association of a page with an + * object cgroups vector + * @page: a pointer to the page struct + * + * Clears an association of a page with an object cgroups vector + */ +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 40220b7bf96d..69e3dbb3d2cf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2895,7 +2895,7 @@ 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); @@ -2923,7 +2923,7 @@ 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 5ac89260f329..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's memory cgroup and obj_cgroups vector 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;