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 66E65C432C0 for ; Mon, 25 Nov 2019 14:45:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 29BA52068F for ; Mon, 25 Nov 2019 14:45:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JpA1xa0k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29BA52068F 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 D4C626B05D6; Mon, 25 Nov 2019 09:45:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CD65D6B05D7; Mon, 25 Nov 2019 09:45:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC5746B05D8; Mon, 25 Nov 2019 09:45:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0163.hostedemail.com [216.40.44.163]) by kanga.kvack.org (Postfix) with ESMTP id A60316B05D6 for ; Mon, 25 Nov 2019 09:45:55 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 8202F249E for ; Mon, 25 Nov 2019 14:45:55 +0000 (UTC) X-FDA: 76195074270.16.title17_169687d36e55a X-HE-Tag: title17_169687d36e55a X-Filterd-Recvd-Size: 4302 Received: from mail-io1-f66.google.com (mail-io1-f66.google.com [209.85.166.66]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Mon, 25 Nov 2019 14:45:55 +0000 (UTC) Received: by mail-io1-f66.google.com with SMTP id k24so5851642ioc.4 for ; Mon, 25 Nov 2019 06:45:54 -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=W8P0JDO7fpifGFPlHrOCHbQzo5o38rhP9abR9IlKbPU=; b=JpA1xa0kXkgHK86oLMnJmG4KfAtRDIj4H7vgBHy6PcaVlX3xoSkmtVs9OGYXjLbu96 fSeWoPSUB3TVcZi8FFMjI/kYxq37GYeYWHMYrMbCCSDpBfmyrD7rbdit8urdK9OSlkDY fs+tr8TicPVe7N0w4pOk/vtwthotksQYonYMqtO/PN61+lca2FvJcKioljEBBh+6hcl5 veR3HfFLX8+NuJpYe7vU8RCDH0BJmDMv+ZCt/lmOjd6mZyAiwu3rM2TdxL583mJJdVR1 O2Gm/OqPLf6QocnC5HYfwsSG40B9RW4g4w6SkZQvfXk8H6UEqpQpmpgf249JM2o1qsL5 M8Xw== 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=W8P0JDO7fpifGFPlHrOCHbQzo5o38rhP9abR9IlKbPU=; b=udzgpuPA/NgA16lCjrTZS9kSWwAv1mL1dLdd0h88w6L8eyJCIhFRY1LXdW5lLV7DhL z5rB/+0+cWQhprerivtc5o9TOL5ubsjvs41ck2Niz4RsKmaRDsFKNctgARTGvaaiTKI5 fyJvJeTLfwm558kT6scj9SvDSXDSFIpTdpz6D0CbWzVXlipkI4+UGiWuGRHXch5ntj5x mjsohWpnh4bo7+f2ZcyNrSCSpf63kMRxe3YnMFl7OPixXXHGbvL1SxAlj67Ii/tCoEyt ZeQb9WjLIW9tEn76JbN4dyD3Y+eab/jxFDWMLaRJ/EIlZv6fTTFi8QM01ASXw+0rkNCl zapw== X-Gm-Message-State: APjAAAWn2mB1Kjtoel0x4yW+AEXnz8wne4vgOxDhDVDGg1odgnUPUiW9 +8duyCTIZbfurv4lPDedDF1AA8t0oeRx2jfGnes= X-Google-Smtp-Source: APXvYqx+EFl0KESN8gPGx0be6x9B0u19O3YKxV4H5s/0T1QIzkMYuO0fjWZBVuK+bQrZdvpmMei03GXCit85ickEZkM= X-Received: by 2002:a5d:9909:: with SMTP id x9mr10642678iol.93.1574693154464; Mon, 25 Nov 2019 06:45:54 -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> <20191125123123.GL31714@dhcp22.suse.cz> <20191125124553.GM31714@dhcp22.suse.cz> <20191125142150.GP31714@dhcp22.suse.cz> <20191125144213.GB602168@cmpxchg.org> In-Reply-To: <20191125144213.GB602168@cmpxchg.org> From: Yafang Shao Date: Mon, 25 Nov 2019 22:45:18 +0800 Message-ID: Subject: Re: [PATCH] mm, memcg: clear page protection when memcg oom group happens To: Johannes Weiner Cc: Michal Hocko , 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 10:42 PM Johannes Weiner wrote: > > On Mon, Nov 25, 2019 at 03:21:50PM +0100, Michal Hocko wrote: > > On Mon 25-11-19 22:11:15, Yafang Shao wrote: > > > When there're no processes, we don't need to protect the pages. You > > > can consider it as 'fault tolerance' . > > > > I have already tried to explain why this is a bold statement that > > doesn't really hold universally and that the kernel doesn't really have > > enough information to make an educated guess. > > I agree, this is not obviously true. And the kernel shouldn't try to > guess whether the explicit userspace configuration is still desirable > to userspace or not. Should we also delete the cgroup when it becomes > empty for example? > > It's better to implement these kinds of policy decisions from > userspace. > > There is a cgroup.events file that can be polled, and its "populated" > field shows conveniently whether there are tasks in a subtree or > not. You can use that to clear protection settings. Thanks for you information. I will take a look at it. Thanks Yafang