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 1453FC54FD0 for ; Fri, 24 Apr 2020 13:11:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CC12320736 for ; Fri, 24 Apr 2020 13:11:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KcKIbzi3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC12320736 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 757568E0005; Fri, 24 Apr 2020 09:11:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 707B68E0003; Fri, 24 Apr 2020 09:11:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 61CDD8E0005; Fri, 24 Apr 2020 09:11:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0191.hostedemail.com [216.40.44.191]) by kanga.kvack.org (Postfix) with ESMTP id 494278E0003 for ; Fri, 24 Apr 2020 09:11:27 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0E3DD180AD81F for ; Fri, 24 Apr 2020 13:11:27 +0000 (UTC) X-FDA: 76742785014.23.shake19_8106588252204 X-HE-Tag: shake19_8106588252204 X-Filterd-Recvd-Size: 4098 Received: from mail-il1-f195.google.com (mail-il1-f195.google.com [209.85.166.195]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Apr 2020 13:11:26 +0000 (UTC) Received: by mail-il1-f195.google.com with SMTP id u189so9213191ilc.4 for ; Fri, 24 Apr 2020 06:11:26 -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=kpgZoqrV7vV3TcMiu1TtDaIjMxaQ7eQG0RjdnsGxrLg=; b=KcKIbzi3DLHmkbSolHBgFeOo113vE9fQVC/EzBfY08JbS017GrQPRK4m8ZpkqGeFf/ 5wtLajB5q+dZsXiSKClvBOQI/9Vw/NPyHyzarIC4CygYXBpNv5Ig+g48bnx74K7c3gWJ 5NGp0TXdl+FCncDQ0a+dhr6QOBIsao+gVbxNqGoA1YcYVV/8hCgG7m8Xxb5wZS7Syk94 EK5iGRfRCZLjZFtPmwaZfi5aPO6Vt2RvTXbistEV85IHiVMfIC27iULZk9/2uWPvcNWe SG/BAJYq27ZhfAnsTzM57weaaWGXyf/OaxZiTxb+dE5Z3aC8InfIEuIV5igzGh7rKS23 0c9g== 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=kpgZoqrV7vV3TcMiu1TtDaIjMxaQ7eQG0RjdnsGxrLg=; b=R/RPU0JQuDgE51+CRYFO2DeCXzTjEySBt+PIBvU4FhnmnoBqWw9qSmgpSLzdWB2AJZ mphySaPn4eTwk9JOjXCRDlZ+tJPJVshqIy/AEW6B4TmlzSWdfJn16QxOWfRsc50MtDQO ZJvk4cM7FOO8U3FUJ3nrnHtgA1aAktCxk5Hjb+L5HJxUxBnjKf7zJURDurexds5PdDiL aEpIUASdcTYFsqW5nieyQyCMZrTabIbI+/eBPj5YqksaX28MIQKWKGAliNIB2HWF/CtF gZRB98F6Z/Aaz0rPqAVcouj98sw4kjkxkdGOxk8GgQBgm0RanLt+3l3ZPt8XN5HeMVUs weZg== X-Gm-Message-State: AGi0PuYjcuCl+Zp0klnxXzF9VjjGPjoZNUWcnoFuc1ZXVpiZsLj1Jse8 x/aUKTz3JV27cc3nLt9dOnlPJXxeBtRtK39yEEg= X-Google-Smtp-Source: APiQypLMFAmObUQ+ZN1CjLt8QbT7uwZUxYjZFYt2fNzbpkpPFmN2Ma1yprLb0ksa/qMOazDSNK5FPdpjZ3KRZggvyJA= X-Received: by 2002:a92:c004:: with SMTP id q4mr8154017ild.93.1587733886020; Fri, 24 Apr 2020 06:11:26 -0700 (PDT) MIME-Version: 1.0 References: <20200423061629.24185-1-laoar.shao@gmail.com> <20200423153323.GA1318256@chrisdown.name> <20200424121836.GA1379200@chrisdown.name> <20200424130554.GA1462690@chrisdown.name> In-Reply-To: <20200424130554.GA1462690@chrisdown.name> From: Yafang Shao Date: Fri, 24 Apr 2020 21:10:49 +0800 Message-ID: Subject: Re: [PATCH] mm, memcg: fix wrong mem cgroup protection To: Chris Down Cc: Andrew Morton , Michal Hocko , Vladimir Davydov , Linux MM , Roman Gushchin , stable@vger.kernel.org, Johannes Weiner 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, Apr 24, 2020 at 9:05 PM Chris Down wrote: > > I'm not debating whether your test case is correct or not, or whether the > numbers are correct or not. The point is that 3 out of 4 people from mm list > who have looked at this patch have no idea what it's trying to do, why it's > important, or why these numbers *should* necessarily be wrong. > > It's good that you have provided a way to demonstrate the effects of your > changes, but one can't solve cognitive gaps with testing. If one could, then > things like TDD would be effective on complex projects -- but they aren't[0]. > > We're really getting off in the weeds here, though. I just want to make it > clear to you that if you think "more testing" is a solution to kernel ailments > like this, you're going to be disappointed. > > 0: http://people.brunel.ac.uk/~csstmms/FucciEtAl_ESEM2016.pdf Hi Chris, Pls. answer my question directly - what should protection be if memcg is the target memcg ? If you can't answer my quesiont, I suggest to revist your patch. -- Thanks Yafang