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 8D2EAC432C3 for ; Mon, 25 Nov 2019 12:17:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4EB0A20674 for ; Mon, 25 Nov 2019 12:17:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jIRVTOvo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EB0A20674 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 CD27C6B05AB; Mon, 25 Nov 2019 07:17:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C82BD6B05AD; Mon, 25 Nov 2019 07:17:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B719F6B05B1; Mon, 25 Nov 2019 07:17:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id 9D4B16B05AB for ; Mon, 25 Nov 2019 07:17:52 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 533FD4857 for ; Mon, 25 Nov 2019 12:17:52 +0000 (UTC) X-FDA: 76194701184.22.stem84_279343f67d501 X-HE-Tag: stem84_279343f67d501 X-Filterd-Recvd-Size: 4766 Received: from mail-il1-f193.google.com (mail-il1-f193.google.com [209.85.166.193]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Mon, 25 Nov 2019 12:17:51 +0000 (UTC) Received: by mail-il1-f193.google.com with SMTP id s75so13998669ilc.3 for ; Mon, 25 Nov 2019 04:17:51 -0800 (PST) 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=vvHUhNvzUMKVG6tcIGPD0tARKKJwdThFryOEXFaMdik=; b=jIRVTOvoMtqjmGcGYSv6MAyMPIzkAgpEENIVq7rLqMwhMMk5vSrTaDIRyAc/wElneO EN6sRD7k1fOHagJTpGcqAC16w5iWfQ+LibqcVea7iQJrOZcvm2151f7c0RlrGELvTKNs 0PMJz6PAbkHKG2BrCHwBdR3eqXl9OvqbGmvqp1vuj6C9sguqz9AVJPrl8cA6XLgb8vpt yV8NYTCleZdaJsibdMyEW+3gD4GwoBUWz6SCeFaUfGiVVABVqYSsm0wvdr+vjrEqv7s4 etBMZqvWu2uiXUtteHHBN+7L6WWQGxXcrUFLWfVU8RQHyJEMOE8xiJTh7KYwkZPZTj47 uzwg== 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=vvHUhNvzUMKVG6tcIGPD0tARKKJwdThFryOEXFaMdik=; b=q+zV+pjr01xCMQmc4UKy5guNx9XKOntTZ5g0O/5ucW3gGwvVyVKWim7iqNDuacQrIC SrUpHx1xC6KhFd2S+rdislNbG1chxZOM2Odl4Y8s51YPzG6F9L5HtFlKsgget00uWsGI uAhdWatPo2HK7MQ3tU8vfP1dlaD0EoGi0Rb1FDBQOx9zs6owdQIAmHXsEAoFUWAYUjw/ hv6Y7eCn7khlv9UqEHM4yfasBktYsgyLGj/mhU7lCEq3nREcE4yqac55QFrJ5uQQGiyS uPd6SNmXSHZqEtsbU0oLhsO/mlGM7U+MIfwXL7ig2g+9AbRAlfUptXFVILHiwSjIfVOn U7nQ== X-Gm-Message-State: APjAAAWT1q5LVCh94XmcCD5PMKgff+KXWJOTDlzKdv48cX85kjlU3gH+ e9px6AdBRAGIyYoiUlWrVtHDytapZWl9pvGNJirQyfHe82w= X-Google-Smtp-Source: APXvYqzIbfKMwL2qqa9RsSzPDKGi6eSZxyY1sQ0EyU/pHshzzlFTyU3dOwt5tjj0iZw48R2RUv/Qpz3dhtuvVn33QuU= X-Received: by 2002:a92:8404:: with SMTP id l4mr34494801ild.137.1574684271123; Mon, 25 Nov 2019 04:17:51 -0800 (PST) MIME-Version: 1.0 References: <1574676893-1571-1-git-send-email-laoar.shao@gmail.com> <20191125110848.GH31714@dhcp22.suse.cz> <20191125115409.GJ31714@dhcp22.suse.cz> In-Reply-To: <20191125115409.GJ31714@dhcp22.suse.cz> From: Yafang Shao Date: Mon, 25 Nov 2019 20:17:15 +0800 Message-ID: Subject: Re: [PATCH] mm, memcg: clear page protection when memcg oom group happens To: Michal Hocko Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Linux MM 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 Mon, Nov 25, 2019 at 7:54 PM Michal Hocko wrote: > > On Mon 25-11-19 19:37:59, Yafang Shao wrote: > > On Mon, Nov 25, 2019 at 7:08 PM Michal Hocko wrote: > > > > > > On Mon 25-11-19 05:14:53, Yafang Shao wrote: > > > > We set memory.oom.group to make all processes in this memcg are killed by > > > > OOM killer to free more pages. In this case, it doesn't make sense to > > > > protect the pages with memroy.{min, low} again if they are set. > > > > > > I do not see why? What does group OOM killing has anything to do with > > > the reclaim protection? What is the actual problem you are trying to > > > solve? > > > > > > > The cgroup is treated as a indivisible workload when cgroup.oom.group > > is set and OOM killer is trying to kill a prcess in this cgroup. > > Yes this is true. > > > We set cgroup.oom.group is to guarantee the workload integrity, now > > that processes ara all killed, why keeps the page cache here? > > Because an administrator has configured the reclaim protection in a > certain way and hopefully had a good reason to do that. We are not going > to override that configure just because there is on OOM killer invoked > and killed tasks in that memcg. The workload might get restarted and it > would run under a different constrains all of the sudden which is not > expected. > > In short kernel should never silently change the configuration made by > an admistrator. Understood. So what about bellow changes ? We don't override the admin setting, but we reclaim the page caches from it if this memcg is oom killed. Something like, mem_cgroup_protected { ... + if (!cgroup_is_populated(memcg->css.cgroup) && mem_cgroup_under_oom_group_kill(memcg)) + return MEMCG_PROT_NONE; + usage = page_counter_read(&memcg->memory); if (!usage) return MEMCG_PROT_NONE; }