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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 5304EC2BBC7 for ; Tue, 14 Apr 2020 00:41:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1117920CC7 for ; Tue, 14 Apr 2020 00:41:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="np0EAQVn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1117920CC7 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 9C3578E0003; Mon, 13 Apr 2020 20:41:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 974398E0001; Mon, 13 Apr 2020 20:41:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 862A68E0003; Mon, 13 Apr 2020 20:41:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0105.hostedemail.com [216.40.44.105]) by kanga.kvack.org (Postfix) with ESMTP id 6D0A78E0001 for ; Mon, 13 Apr 2020 20:41:55 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 33A1D181AEF1F for ; Tue, 14 Apr 2020 00:41:55 +0000 (UTC) X-FDA: 76704608190.17.grass90_8524b5c00350d X-HE-Tag: grass90_8524b5c00350d X-Filterd-Recvd-Size: 4429 Received: from mail-io1-f66.google.com (mail-io1-f66.google.com [209.85.166.66]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Apr 2020 00:41:54 +0000 (UTC) Received: by mail-io1-f66.google.com with SMTP id y17so11403663iow.9 for ; Mon, 13 Apr 2020 17:41:54 -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=HlavIvaaNds85GLQ5z8/oP0O9rNUrTQr5Z3E8erJn+0=; b=np0EAQVnkyWkJqEjk1BqoJlb2LWNjE9yJq0cGxdvN3OQ4jn4scMhYN75VK25/jrMvO OosbAemM46NOAQ88Z/i2wTi99MoctlUUSc4DGTfQsDuW4e8LNot9USDi2wu6wEFuDfdE V03nHrLG7z+FQpmE+iTN1oSrbvD7xDOLlsbx9N6+hF4utHCkw3LaggpA0/TXfusDWeCq Zh/5Wz5H+dG7l8tFNG6WfgCqAnJdtlHwTnvUvc9/lIm2cU6qZRD6lpO+zQFbqD/Di5eK WRTMGl/t4ipqqwNB6dvC59pq7VLxbx6w6mr1Q7F9qmqr21jxvBI9YW+N66nAv1AL6PfB 9xnw== 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=HlavIvaaNds85GLQ5z8/oP0O9rNUrTQr5Z3E8erJn+0=; b=IO4QoNZowAQtItM/H4gHU6VTbUh0zOrLGvFJc1GL8NSAOApfZ6o00LSxr3lBbgf+nh e8gI6CfBuDsaTcVg3vO5aB21S+oukqFKK576OC+yzQDlWkGmE4h1KARLDswoQHLrU78j JFJsWZ/6BK88fy++Kz9Ta9sV3lbQnk+T77u4w/lTSWqR6z6554GSaC/BUIK0RYUevZZW mIy4nAVBmMladKpP2N6ijojbDlKJLyzgvAk8S9DOuPY6f3Eus+9lnFEztwm4RIpoq7Ef Hu3wSlmwZVRguSKJtA+2Wk5YCm15ao+00zzC0E2amjBjkBGb8PsJuVYlneCm9bORLzhy ybxQ== X-Gm-Message-State: AGi0PuZ7uRJBSvOH6RNJjYVex7GsItEurttNmogcRBuazSnmb/SLMkJ5 9MHK5SL11S4z3H5ofs2C1fwHrn6wBTaYpaJFs5c= X-Google-Smtp-Source: APiQypIJnbC6b13RwLCDLQJJK9YuSUShjPTSL0jl90YC4sJbPKrNBLeGV+zhV64EN0soB6WGaEsBfDhpZPjZL32c7c0= X-Received: by 2002:a02:716b:: with SMTP id n43mr18305172jaf.97.1586824914341; Mon, 13 Apr 2020 17:41:54 -0700 (PDT) MIME-Version: 1.0 References: <20200412140427.6732-1-laoar.shao@gmail.com> <20200413193111.GA1559372@chrisdown.name> In-Reply-To: <20200413193111.GA1559372@chrisdown.name> From: Yafang Shao Date: Tue, 14 Apr 2020 08:41:18 +0800 Message-ID: Subject: Re: [PATCH] mm, memcg: fix inconsistent oom event behavior To: Chris Down Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Linux MM , Shakeel Butt , stable@vger.kernel.org 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 Tue, Apr 14, 2020 at 3:31 AM Chris Down wrote: > > Hi Yafang, > > Yafang Shao writes: > >A recent commit 9852ae3fe529 ("mm, memcg: consider subtrees in > >memory.events") changes the behavior of memcg events, which will > >consider subtrees in memory.events. But oom_kill event is a special one > >as it is used in both cgroup1 and cgroup2. In cgroup1, it is displayed > >in memory.oom_control. The file memory.oom_control is in both root memcg > >and non root memcg, that is different with memory.event as it only in > >non-root memcg. That commit is okay for cgroup2, but it is not okay for > >cgroup1 as it will cause inconsistent behavior between root memcg and > >non-root memcg. > >Let's recover the original behavior for cgroup1. > > Can you please explain the practical ramifications of this and show an > explicitly laid out example of how this manifests, with numbers and scenarios? > It's unclear to me that this is a real problem as is -- it may be, but there > certainly needs to be more information. > Here's an example. root memcg / memcg foo / memcg bar Suppose there's an oom_kill in memcg bar, then the oon_kill will be root memcg : memory.oom_control(oom_kill) 0 / memcg foo : memory.oom_control(oom_kill) 1 / memcg bar : memory.oom_control(oom_kill) 1 Then the user has to know whether the memcg is root or not, if it is root memcg, then memory.oom_control(oom_kill) is its local event only, while if it is not root memcg, then memory.oom_control(oom_kill) includes all its descendants' oom_kill events. Thanks Yafang