From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 94AD26B0266 for ; Tue, 19 Jun 2018 01:13:50 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id o19-v6so6040659pgn.14 for ; Mon, 18 Jun 2018 22:13:50 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id l66-v6sor4850184pfi.22.2018.06.18.22.13.49 for (Google Transport Security); Mon, 18 Jun 2018 22:13:49 -0700 (PDT) From: Shakeel Butt Subject: [PATCH 3/3] fs, mm: account buffer_head to kmemcg Date: Mon, 18 Jun 2018 22:13:27 -0700 Message-Id: <20180619051327.149716-4-shakeelb@google.com> In-Reply-To: <20180619051327.149716-1-shakeelb@google.com> References: <20180619051327.149716-1-shakeelb@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michal Hocko , Johannes Weiner , Vladimir Davydov , Jan Kara , Greg Thelen , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Jan Kara , Alexander Viro The buffer_head can consume a significant amount of system memory and is directly related to the amount of page cache. In our production environment we have observed that a lot of machines are spending a significant amount of memory as buffer_head and can not be left as system memory overhead. Charging buffer_head is not as simple as adding __GFP_ACCOUNT to the allocation. The buffer_heads can be allocated in a memcg different from the memcg of the page for which buffer_heads are being allocated. One concrete example is memory reclaim. The reclaim can trigger I/O of pages of any memcg on the system. So, the right way to charge buffer_head is to extract the memcg from the page for which buffer_heads are being allocated and then use targeted memcg charging API. Signed-off-by: Shakeel Butt Cc: Jan Kara Cc: Greg Thelen Cc: Michal Hocko Cc: Johannes Weiner Cc: Vladimir Davydov Cc: Alexander Viro Cc: Andrew Morton --- fs/buffer.c | 14 +++++++++++++- include/linux/memcontrol.h | 7 +++++++ mm/memcontrol.c | 21 +++++++++++++++++++++ 3 files changed, 41 insertions(+), 1 deletion(-) diff --git a/fs/buffer.c b/fs/buffer.c index 8194e3049fc5..26389b7a3cab 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -815,10 +815,17 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, struct buffer_head *bh, *head; gfp_t gfp = GFP_NOFS; long offset; + struct mem_cgroup *old_memcg; + struct mem_cgroup *memcg = get_mem_cgroup_from_page(page); if (retry) gfp |= __GFP_NOFAIL; + if (memcg) { + gfp |= __GFP_ACCOUNT; + old_memcg = memalloc_memcg_save(memcg); + } + head = NULL; offset = PAGE_SIZE; while ((offset -= size) >= 0) { @@ -835,6 +842,11 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, /* Link the buffer to its page */ set_bh_page(bh, page, offset); } +out: + if (memcg) { + memalloc_memcg_restore(old_memcg); +#ifdef CONFIG_MEMCG + css_put(&memcg->css); +#endif + } return head; /* * In case anything failed, we just free everything we got. @@ -848,7 +860,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, } while (head); } - return NULL; + goto out; } EXPORT_SYMBOL_GPL(alloc_page_buffers); diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 6c857be8a9b7..d53609978eb7 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -380,6 +380,8 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm); +struct mem_cgroup *get_mem_cgroup_from_page(struct page *page); + static inline struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){ return css ? container_of(css, struct mem_cgroup, css) : NULL; @@ -864,6 +866,11 @@ static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) return NULL; } +static inline struct mem_cgroup *get_mem_cgroup_from_page(struct page *page) +{ + return NULL; +} + static inline void mem_cgroup_put(struct mem_cgroup *memcg) { } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c481e661e051..f9a9a79117b9 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -712,6 +712,27 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) return memcg; } +/** + * get_mem_cgroup_from_page: Obtain a reference on given page's memcg. + * @page: page from which memcg should be extracted. + * + * Obtain a reference on page->memcg and returns it if successful. Otherwise + * NULL is returned. + */ +struct mem_cgroup *get_mem_cgroup_from_page(struct page *page) +{ + struct mem_cgroup *memcg = page->mem_cgroup; + + if (mem_cgroup_disabled() || !memcg) + return NULL; + + rcu_read_lock(); + if (!css_tryget_online(&memcg->css)) + memcg = NULL; + rcu_read_unlock(); + return memcg; +} + static __always_inline struct mem_cgroup *get_mem_cgroup( struct mem_cgroup *memcg, struct mm_struct *mm) { -- 2.18.0.rc1.244.gcf134e6275-goog