From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by kanga.kvack.org (Postfix) with ESMTP id EF9F78E0001 for ; Sun, 20 Jan 2019 18:16:13 -0500 (EST) Received: by mail-qt1-f198.google.com with SMTP id z6so19119465qtj.21 for ; Sun, 20 Jan 2019 15:16:13 -0800 (PST) Received: from mail-sor-f73.google.com (mail-sor-f73.google.com. [209.85.220.73]) by mx.google.com with SMTPS id l15sor107011993qtr.63.2019.01.20.15.16.12 for (Google Transport Security); Sun, 20 Jan 2019 15:16:12 -0800 (PST) Date: Sun, 20 Jan 2019 15:15:51 -0800 In-Reply-To: Message-Id: <20190120231551.213847-1-shakeelb@google.com> Mime-Version: 1.0 References: Subject: memory cgroup pagecache and inode problem From: Shakeel Butt Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi , Fam Zheng Cc: cgroups@vger.kernel.org, Linux MM , tj@kernel.org, Johannes Weiner , lizefan@huawei.com, Michal Hocko , Vladimir Davydov , duanxiongchun@bytedance.com, =?UTF-8?q?=E5=BC=A0=E6=B0=B8=E8=82=83?= , liuxiaozhou@bytedance.com, Shakeel Butt On Wed, Jan 16, 2019 at 9:07 PM Yang Shi wrote: ... > > > You mean it solves the problem by retrying more times? Actually, I'm > > > not sure if you have swap setup in your test, but force_empty does do > > > swap if swap is on. This may cause it can't reclaim all the page cache > > > in 5 retries. I have a patch within that series to skip swap. > > > > Basically yes, retrying solves the problem. But compared to immediate retries, a scheduled retry in a few seconds is much more effective. > > This may suggest doing force_empty in a worker is more effective in > fact. Not sure if this is good enough to convince Johannes or not. > >>From what I understand what we actually want is to force_empty an offlined memcg. How about we change the semantics of force_empty on root_mem_cgroup? Currently force_empty on root_mem_cgroup returns -EINVAL. Rather than that, let's do force_empty on all offlined memcgs if user does force_empty on root_mem_cgroup. Something like following. --- mm/memcontrol.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a4ac554be7e8..51daa2935c41 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2898,14 +2898,16 @@ static inline bool memcg_has_children(struct mem_cgroup *memcg) * * Caller is responsible for holding css reference for memcg. */ -static int mem_cgroup_force_empty(struct mem_cgroup *memcg) +static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool online) { int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; /* we call try-to-free pages for make this cgroup empty */ - lru_add_drain_all(); - drain_all_stock(memcg); + if (online) { + lru_add_drain_all(); + drain_all_stock(memcg); + } /* try to free all pages in this cgroup */ while (nr_retries && page_counter_read(&memcg->memory)) { @@ -2915,7 +2917,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) return -EINTR; progress = try_to_free_mem_cgroup_pages(memcg, 1, - GFP_KERNEL, true); + GFP_KERNEL, online); if (!progress) { nr_retries--; /* maybe some writeback is necessary */ @@ -2932,10 +2934,16 @@ static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + struct mem_cgroup *mi; - if (mem_cgroup_is_root(memcg)) - return -EINVAL; - return mem_cgroup_force_empty(memcg) ?: nbytes; + if (mem_cgroup_is_root(memcg)) { + for_each_mem_cgroup_tree(mi, memcg) { + if (!mem_cgroup_online(mi)) + mem_cgroup_force_empty(mi, false); + } + return 0; + } + return mem_cgroup_force_empty(memcg, true) ?: nbytes; } static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css, -- 2.20.1.321.g9e740568ce-goog From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6025AC312E2 for ; 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[209.85.220.73]) by mx.google.com with SMTPS id l15sor107011993qtr.63.2019.01.20.15.16.12 for (Google Transport Security); Sun, 20 Jan 2019 15:16:12 -0800 (PST) Received-SPF: pass (google.com: domain of 3paffxagkcdspexhbbiydlldib.zljifkru-jjhsxzh.lod@flex--shakeelb.bounces.google.com designates 209.85.220.73 as permitted sender) client-ip=209.85.220.73; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=sF18++4H; spf=pass (google.com: domain of 3paffxagkcdspexhbbiydlldib.zljifkru-jjhsxzh.lod@flex--shakeelb.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3PAFFXAgKCDspeXhbbiYdlldib.Zljifkru-jjhsXZh.lod@flex--shakeelb.bounces.google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=c3o0SX1EcTLKZLgoGhVUqzZpnqsfWcLGF/pNqNohEcA=; b=sF18++4Hbk/acIU1Sl8XkBCFAvC4j5XQqvg8A5LX8cCPuSjcsiXxxaCH/Q8+6lknnW kD1N8rBEs+OSwmX1uQHlbwPHgkD7xHFLl0UwbLbx3m6VQqMzLE7Yo8D4T3tGQXb6jtlH H4pisxKZBWoU2MIwiydTAFp7Wvt8uJR4wNo9jG8uVmStvX1wbPMpJM88paD0ItRrQO0n yIsh1wn/jJwfEJyAEV+ygsfRUFUAYxy0yl/FscYhdJqQAOZ+temPB+5RTtPjPWILz3Wx +uwzwk9QdUHJ5C0iIgzynMgQW0EJee2pAHcDu5GEgHiKTITuqkNaou1jQcAGgLqvMlq1 8Jqw== X-Google-Smtp-Source: ALg8bN7RdNVzQoEyncOsT1RWzMUyfExI+JAEZGVwhDQF8pzmy/Nx8QMgTI1lSbD2dRRxiv1oc8YxAwUQo8Ftlg== X-Received: by 2002:ac8:2a15:: with SMTP id k21mr18957405qtk.49.1548026172373; Sun, 20 Jan 2019 15:16:12 -0800 (PST) Date: Sun, 20 Jan 2019 15:15:51 -0800 In-Reply-To: Message-Id: <20190120231551.213847-1-shakeelb@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.20.1.321.g9e740568ce-goog Subject: memory cgroup pagecache and inode problem From: Shakeel Butt To: Yang Shi , Fam Zheng Cc: cgroups@vger.kernel.org, Linux MM , tj@kernel.org, Johannes Weiner , lizefan@huawei.com, Michal Hocko , Vladimir Davydov , duanxiongchun@bytedance.com, "=?UTF-8?q?=E5=BC=A0=E6=B0=B8=E8=82=83?=" , liuxiaozhou@bytedance.com, Shakeel Butt Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20190120231551.NlPYwhDDkt0S1k7xwzc22UZTMMkOXbs1UML2wWw6e2U@z> On Wed, Jan 16, 2019 at 9:07 PM Yang Shi wrote: ... > > > You mean it solves the problem by retrying more times? Actually, I'm > > > not sure if you have swap setup in your test, but force_empty does do > > > swap if swap is on. This may cause it can't reclaim all the page cache > > > in 5 retries. I have a patch within that series to skip swap. > > > > Basically yes, retrying solves the problem. But compared to immediate retries, a scheduled retry in a few seconds is much more effective. > > This may suggest doing force_empty in a worker is more effective in > fact. Not sure if this is good enough to convince Johannes or not. > >From what I understand what we actually want is to force_empty an offlined memcg. How about we change the semantics of force_empty on root_mem_cgroup? Currently force_empty on root_mem_cgroup returns -EINVAL. Rather than that, let's do force_empty on all offlined memcgs if user does force_empty on root_mem_cgroup. Something like following. --- mm/memcontrol.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a4ac554be7e8..51daa2935c41 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2898,14 +2898,16 @@ static inline bool memcg_has_children(struct mem_cgroup *memcg) * * Caller is responsible for holding css reference for memcg. */ -static int mem_cgroup_force_empty(struct mem_cgroup *memcg) +static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool online) { int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; /* we call try-to-free pages for make this cgroup empty */ - lru_add_drain_all(); - drain_all_stock(memcg); + if (online) { + lru_add_drain_all(); + drain_all_stock(memcg); + } /* try to free all pages in this cgroup */ while (nr_retries && page_counter_read(&memcg->memory)) { @@ -2915,7 +2917,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) return -EINTR; progress = try_to_free_mem_cgroup_pages(memcg, 1, - GFP_KERNEL, true); + GFP_KERNEL, online); if (!progress) { nr_retries--; /* maybe some writeback is necessary */ @@ -2932,10 +2934,16 @@ static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of, loff_t off) { struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); + struct mem_cgroup *mi; - if (mem_cgroup_is_root(memcg)) - return -EINVAL; - return mem_cgroup_force_empty(memcg) ?: nbytes; + if (mem_cgroup_is_root(memcg)) { + for_each_mem_cgroup_tree(mi, memcg) { + if (!mem_cgroup_online(mi)) + mem_cgroup_force_empty(mi, false); + } + return 0; + } + return mem_cgroup_force_empty(memcg, true) ?: nbytes; } static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css, -- 2.20.1.321.g9e740568ce-goog