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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 C040DC47247 for ; Fri, 1 May 2020 02:13:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 529CA2054F for ; Fri, 1 May 2020 02:13:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Xog+ZZ3l" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 529CA2054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C3EB78E0005; Thu, 30 Apr 2020 22:13:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BEF3A8E0001; Thu, 30 Apr 2020 22:13:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B05EF8E0005; Thu, 30 Apr 2020 22:13:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0037.hostedemail.com [216.40.44.37]) by kanga.kvack.org (Postfix) with ESMTP id 965E28E0001 for ; Thu, 30 Apr 2020 22:13:37 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 4EC17181AC9CB for ; Fri, 1 May 2020 02:13:37 +0000 (UTC) X-FDA: 76766528874.25.stamp88_1f90fa81ddb2f X-HE-Tag: stamp88_1f90fa81ddb2f X-Filterd-Recvd-Size: 8542 Received: from mail-io1-f68.google.com (mail-io1-f68.google.com [209.85.166.68]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Fri, 1 May 2020 02:13:36 +0000 (UTC) Received: by mail-io1-f68.google.com with SMTP id y26so3709534ioj.2 for ; Thu, 30 Apr 2020 19:13:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EYDJWeCLlhw8lr2MHLhmVsV4j9mOvkGGvmRilWGWRrg=; b=Xog+ZZ3lCM/XaSVs+gBhESPLwp4WAlt3K7H146kG7Z6OxZj41VMjwJnXT9s0237dpB 76vjiueRHg/SNAru0/gtuf3l91l4oxhxmb5/7eL/SDC4k/AFQg+5u8uUXvtlQe0pYsp1 kmV2qpDLJxmzAS57vYTIDZPyMZ/L/Vh538ALb35lYy2T9/Jf4IzLli2P/PV9VC5czGcG QXImWSoImGoev+0CYE7RKP6UKUoKP12x6/KC0ActMx6SzeN/o8EEAntBDBAYQ4aKFAKG b4MT7QU1JXNPMA6mQFNCPs+5bsFUcN3KbIioAHnyazIpPH91oFDb3sLkoT+/I56sw3nM dm/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EYDJWeCLlhw8lr2MHLhmVsV4j9mOvkGGvmRilWGWRrg=; b=rbnmtgK0q2xi80QThlVob41sjBWzZIuZJ1cze0zvd2/v+M/hmca5gWOdGzb/26gQpk ANulb3raPHdB1M2KpuPzjkUgnHHgfNgYrv+2JURLPuuY3z8eakrO1QE26ka+aqsYccSz tYpMocwyZlHv+K1HE4Jh0jfuqayYnsGaXdpw/YqLlB6zJ4gqVKfDJrWDvkMo/K1NNXcQ NPR6q+HF+BwiIFqp6VSHrFFHXNiIOPTWW1pBL8GAqiiSwpJyK7EI5l3e3CrcolgF+tKd HKZkAB2AWAwUiEQ3EmmQ5sENvTWYK3/gmh2DJsIWzbWcXGJGqxBTcNbLWgtsj4TVzeIn GXnQ== X-Gm-Message-State: AGi0PuaGToeXQU+M6vdHuJN6wKl4MH5P9c6xXhQLaVmmKM9SWzWSsSK3 nSjeWowZ1xi4Si8ZCC79Uo36dRr0s4vicIKv7VA= X-Google-Smtp-Source: APiQypKGz0Gne2nX+o+Qe1qKhOhnsWZuQcjrp1Y5mU4C2lDwzd9brFql0s85v6OJ6EpdeCnNPCbyDLk7pi82FXc9Vvc= X-Received: by 2002:a02:ccad:: with SMTP id t13mr1381837jap.64.1588299215975; Thu, 30 Apr 2020 19:13:35 -0700 (PDT) MIME-Version: 1.0 References: <20200430182712.237526-1-shakeelb@google.com> In-Reply-To: From: Yafang Shao Date: Fri, 1 May 2020 10:12:59 +0800 Message-ID: Subject: Re: [PATCH] memcg: oom: ignore oom warnings from memory.max To: Shakeel Butt Cc: Johannes Weiner , Roman Gushchin , Michal Hocko , Greg Thelen , Andrew Morton , Linux MM , Cgroups , LKML 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: On Fri, May 1, 2020 at 10:04 AM Shakeel Butt wrote: > > On Thu, Apr 30, 2020 at 6:39 PM Yafang Shao wrote: > > > > On Fri, May 1, 2020 at 2:27 AM Shakeel Butt wrote: > > > > > > Lowering memory.max can trigger an oom-kill if the reclaim does not > > > succeed. However if oom-killer does not find a process for killing, it > > > dumps a lot of warnings. > > > > > > > I have been confused by this behavior for several months and I think > > it will confuse more memcg users. > > We should keep the memcg oom behavior consistent with system oom - no > > oom kill if no process. > > > > What about bellow change ? > > > > Seems fine to me. If others are ok with this, please do send a signed-off patch. > Sure, I will. > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index e28098e13f1c..25fbc37a747f 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -6086,6 +6086,9 @@ static ssize_t memory_max_write(struct > > kernfs_open_file *of, > > continue; > > } > > > > + if (!cgroup_is_populated(memcg->css.cgroup)) > > + break; > > + > > memcg_memory_event(memcg, MEMCG_OOM); > > if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0)) > > break; > > > > > Deleting a memcg does not reclaim memory from it and the memory can > > > linger till there is a memory pressure. One normal way to proactively > > > reclaim such memory is to set memory.max to 0 just before deleting the > > > memcg. However if some of the memcg's memory is pinned by others, this > > > operation can trigger an oom-kill without any process and thus can log a > > > lot un-needed warnings. So, ignore all such warnings from memory.max. > > > > > > Signed-off-by: Shakeel Butt > > > --- > > > include/linux/oom.h | 3 +++ > > > mm/memcontrol.c | 9 +++++---- > > > mm/oom_kill.c | 2 +- > > > 3 files changed, 9 insertions(+), 5 deletions(-) > > > > > > diff --git a/include/linux/oom.h b/include/linux/oom.h > > > index c696c265f019..6345dc55df64 100644 > > > --- a/include/linux/oom.h > > > +++ b/include/linux/oom.h > > > @@ -52,6 +52,9 @@ struct oom_control { > > > > > > /* Used to print the constraint info. */ > > > enum oom_constraint constraint; > > > + > > > + /* Do not warn even if there is no process to be killed. */ > > > + bool no_warn; > > > }; > > > > > > extern struct mutex oom_lock; > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 317dbbaac603..a1f00d9b9bb0 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -1571,7 +1571,7 @@ unsigned long mem_cgroup_size(struct mem_cgroup *memcg) > > > } > > > > > > static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > > > - int order) > > > + int order, bool no_warn) > > > { > > > struct oom_control oc = { > > > .zonelist = NULL, > > > @@ -1579,6 +1579,7 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > > > .memcg = memcg, > > > .gfp_mask = gfp_mask, > > > .order = order, > > > + .no_warn = no_warn, > > > }; > > > bool ret; > > > > > > @@ -1821,7 +1822,7 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int > > > mem_cgroup_oom_notify(memcg); > > > > > > mem_cgroup_unmark_under_oom(memcg); > > > - if (mem_cgroup_out_of_memory(memcg, mask, order)) > > > + if (mem_cgroup_out_of_memory(memcg, mask, order, false)) > > > ret = OOM_SUCCESS; > > > else > > > ret = OOM_FAILED; > > > @@ -1880,7 +1881,7 @@ bool mem_cgroup_oom_synchronize(bool handle) > > > mem_cgroup_unmark_under_oom(memcg); > > > finish_wait(&memcg_oom_waitq, &owait.wait); > > > mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask, > > > - current->memcg_oom_order); > > > + current->memcg_oom_order, false); > > > } else { > > > schedule(); > > > mem_cgroup_unmark_under_oom(memcg); > > > @@ -6106,7 +6107,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, > > > } > > > > > > memcg_memory_event(memcg, MEMCG_OOM); > > > - if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0)) > > > + if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0, true)) > > > break; > > > } > > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > index 463b3d74a64a..5ace39f6fe1e 100644 > > > --- a/mm/oom_kill.c > > > +++ b/mm/oom_kill.c > > > @@ -1098,7 +1098,7 @@ bool out_of_memory(struct oom_control *oc) > > > > > > select_bad_process(oc); > > > /* Found nothing?!?! */ > > > - if (!oc->chosen) { > > > + if (!oc->chosen && !oc->no_warn) { > > > dump_header(oc, NULL); > > > pr_warn("Out of memory and no killable processes...\n"); > > > /* > > > -- > > > 2.26.2.526.g744177e7f7-goog > > > > > > > > > > > > -- > > Thanks > > Yafang -- Thanks Yafang