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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 6E158C64EB8 for ; Tue, 9 Oct 2018 11:10:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D8972064E for ; Tue, 9 Oct 2018 11:10:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D8972064E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726731AbeJIS0d (ORCPT ); Tue, 9 Oct 2018 14:26:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:47190 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726393AbeJIS0d (ORCPT ); Tue, 9 Oct 2018 14:26:33 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CAD24AF6F; Tue, 9 Oct 2018 11:10:06 +0000 (UTC) Date: Tue, 9 Oct 2018 13:10:05 +0200 From: Michal Hocko To: Tetsuo Handa Cc: ytk.lee@samsung.com, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Oleg Nesterov , David Rientjes , Vladimir Davydov , Andrew Morton , Linus Torvalds Subject: Re: [PATCH] mm, oom_adj: avoid meaningless loop to find processes sharing mm Message-ID: <20181009111005.GK8528@dhcp22.suse.cz> References: <67eedc4c-7afa-e845-6c88-9716fd820de6@i-love.sakura.ne.jp> <20181008011931epcms1p82dd01b7e5c067ea99946418bc97de46a@epcms1p8> <20181008061407epcms1p519703ae6373a770160c8f912c7aa9521@epcms1p5> <20181008083855epcms1p20e691e5a001f3b94b267997c24e91128@epcms1p2> <20181009063541.GB8528@dhcp22.suse.cz> <20181009075015.GC8528@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 09-10-18 19:00:44, Tetsuo Handa wrote: > On 2018/10/09 16:50, Michal Hocko wrote: [...] > > Well, that is unfortunate indeed and it > > breaks the OOM_SCORE_ADJ_MIN contract. There are basically two ways here > > 1) do not care and encourage users to use a saner way to set > > OOM_SCORE_ADJ_MIN because doing that externally is racy anyway e.g. > > setting it before [v]fork & exec. Btw. do we know about an actual user > > who would care? > > I'm not talking about [v]fork & exec. Why are you talking about [v]fork & exec ? Because that is the only raceless way to set your oom_score_adj. > > 2) add OOM_SCORE_ADJ_MIN and do not kill tasks sharing mm and do not > > reap the mm in the rare case of the race. > > That is no problem. The mistake we made in 4.6 was that we updated oom_score_adj > to -1000 (and allowed unprivileged users to OOM-lockup the system). I do not follow. -- Michal Hocko SUSE Labs