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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 DD8A0C282C8 for ; Mon, 28 Jan 2019 18:15:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A167020882 for ; Mon, 28 Jan 2019 18:15:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A167020882 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 20C4F8E0002; Mon, 28 Jan 2019 13:15:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1BA738E0001; Mon, 28 Jan 2019 13:15:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0AA418E0002; Mon, 28 Jan 2019 13:15:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id C09648E0001 for ; Mon, 28 Jan 2019 13:15:17 -0500 (EST) Received: by mail-pf1-f199.google.com with SMTP id e89so14609821pfb.17 for ; Mon, 28 Jan 2019 10:15:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=YLQfkP1Yh3Zq7Vw4IS447I2kGeznx+nwCzDsqeofSZE=; b=KEcoP+VVPa1HdUd8fTJvJz1XwbncC6vStgkWKKrEKE1e4mPpkHem/Q+cjRnyDyEs+a RTCgJ/i8XA1za7Mf5H+yTqzBco8yKTeYSgJMmlFsKwhu2jAqXaSR4bA94KeEngOrX9SH 2LSGH5Rt9ltv4PnMAr3tJ3DxF5YVJ+AXzLUd0eNlrt2J16iExE+Yd4ve6kb7oGipsmk3 FZc4f+CqVVadZw7VAlJupdN0xiwXmfzjngzZzMjrQIOJ3Fjds9uS8KzPZ1VuHzQCnoVe XJbA57HXGDGnDhj7OIK/4oWPJYrvSM6m6DkmPCBchPZHH4hgpEQxOSudBPZPFkFEX+iO C6jw== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Gm-Message-State: AJcUuke6Rl2icY506och3rB1Q+1Osio+fc6T0cBMVe0ifPUVh3J9JCBW NUzwDfwbfGhDUQQjJ8vPh1L4l1rYBEihNIstEDZBqNkzPj7f60TeggBqF8tc4JnrrI+fVhn+vA4 h1JwD3Yc1da1ZmgzLW6QoihkZaHYjyZRDxsMBNkWoXbLDgJmuxH3DkMEVYnLJOjCxuA== X-Received: by 2002:a63:5455:: with SMTP id e21mr20923111pgm.316.1548699317478; Mon, 28 Jan 2019 10:15:17 -0800 (PST) X-Google-Smtp-Source: ALg8bN75H2sLH+3bwONc8pBjHeubtj7dIGnAyuK9z4zCQLU4GzaBwMNyJbI3kb/rw0jF6/AaXiC6 X-Received: by 2002:a63:5455:: with SMTP id e21mr20923053pgm.316.1548699316624; Mon, 28 Jan 2019 10:15:16 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1548699316; cv=none; d=google.com; s=arc-20160816; b=Ly9Kokk0p15SAlVv7cYcbfj4BItg+5B4Y8rifE2stIhabiQW/oqmZ9qmJJnTde5rt5 QdxweoX02+qHK1b/j7SqdWJ2Qxyyj0akQ8SMRWiYW+NLxua1C2q5YsA6tKFcYLxkaJOh VukozZ11X1A5kLp2Rpjn4WEdakBOp980q+soTu+iLt7NTQdl6d1ap306Peck3QKQFC93 /ovbUe6Dx7PLqAl/ReI29CsQV94zKFkpbYiuwzlYG/G0Sr4pzqpYPWvdwUMf6m5KHLuz VlfUASF2xc7zg9oqqkaEm6Ax+rPgP/OO+tEUVR16PFHgrX/v8SI9cSxOjffhZaF3yZ+a eyRA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date; bh=YLQfkP1Yh3Zq7Vw4IS447I2kGeznx+nwCzDsqeofSZE=; b=xpj8HYQnjldmkeUw/3jqjN7aRZQdiJcFHRpnSDQQmLQPD3/Zo/6NnbS88KhFWq6Bxr EHAkRvw/1PTvA99AlUnppUsh/ToVNcDmhevao4ut2JMh/AGsUSTtrwndpRPe8XDqQ05v Hnv0nfSug1/TNgBSo991zyiZsxHo9MmYXW/+aptc4M+inLwDC5uaK9PpGNkG4zso3Sr1 PBvatFiOMZtF10xXjTABxmIYN5m+1DIRmEJrdf+I6KdGQqfsWWf/F44eiyrBZ0JztJHh Iy79RXgg0FIllAWeaRjYoY3IECIry+OpPX1/lCETDy8I0cIK2fjCaN8omKu8iywZwBNm poKA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id e33si15379747pld.397.2019.01.28.10.15.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 10:15:16 -0800 (PST) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 32F7E25CE; Mon, 28 Jan 2019 18:15:15 +0000 (UTC) Date: Mon, 28 Jan 2019 10:15:13 -0800 From: Andrew Morton To: Tetsuo Handa Cc: Michal Hocko , Arkadiusz =?UTF-8?Q?Mi=C5=9Bkiewicz?= , Tejun Heo , cgroups@vger.kernel.org, Aleksa Sarai , Jay Kamat , Roman Gushchin , Johannes Weiner , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm Subject: Re: [PATCH v3] oom, oom_reaper: do not enqueue same task twice Message-Id: <20190128101513.f35752d6210f0781d0de8d17@linux-foundation.org> In-Reply-To: References: <480296c4-ed7a-3265-e84a-298e42a0f1d5@I-love.SAKURA.ne.jp> <6da6ca69-5a6e-a9f6-d091-f89a8488982a@gmail.com> <72aa8863-a534-b8df-6b9e-f69cf4dd5c4d@i-love.sakura.ne.jp> <33a07810-6dbc-36be-5bb6-a279773ccf69@i-love.sakura.ne.jp> <34e97b46-0792-cc66-e0f2-d72576cdec59@i-love.sakura.ne.jp> <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com> <1d161137-55a5-126f-b47e-b2625bd798ca@i-love.sakura.ne.jp> <20190127083724.GA18811@dhcp22.suse.cz> <20190127114021.GB18811@dhcp22.suse.cz> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 Sun, 27 Jan 2019 23:57:38 +0900 Tetsuo Handa wrote: > Arkadiusz reported that enabling memcg's group oom killing causes > strange memcg statistics where there is no task in a memcg despite > the number of tasks in that memcg is not 0. It turned out that there > is a bug in wake_oom_reaper() which allows enqueuing same task twice > which makes impossible to decrease the number of tasks in that memcg > due to a refcount leak. > > This bug existed since the OOM reaper became invokable from > task_will_free_mem(current) path in out_of_memory() in Linux 4.7, > but memcg's group oom killing made it easier to trigger this bug by > calling wake_oom_reaper() on the same task from one out_of_memory() > request. > > Fix this bug using an approach used by commit 855b018325737f76 > ("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task"). > As a side effect of this patch, this patch also avoids enqueuing > multiple threads sharing memory via task_will_free_mem(current) path. > Do we think this is serious enough to warrant a -stable backport?