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 31423C43142 for ; Tue, 31 Jul 2018 05:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6B37208A3 for ; Tue, 31 Jul 2018 05:09:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6B37208A3 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 S1728226AbeGaGr4 (ORCPT ); Tue, 31 Jul 2018 02:47:56 -0400 Received: from mx2.suse.de ([195.135.220.15]:40220 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726389AbeGaGrz (ORCPT ); Tue, 31 Jul 2018 02:47:55 -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 12CF5ACEF; Tue, 31 Jul 2018 05:09:30 +0000 (UTC) Date: Tue, 31 Jul 2018 07:09:28 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Tejun Heo , Roman Gushchin , Johannes Weiner , Vladimir Davydov , David Rientjes , Andrew Morton , Linus Torvalds , linux-mm , LKML Subject: Re: [PATCH] mm,page_alloc: PF_WQ_WORKER threads must sleep at should_reclaim_retry(). Message-ID: <20180731050928.GA4557@dhcp22.suse.cz> References: <55c9da7f-e448-964a-5b50-47f89a24235b@i-love.sakura.ne.jp> <20180730093257.GG24267@dhcp22.suse.cz> <9158a23e-7793-7735-e35c-acd540ca59bf@i-love.sakura.ne.jp> <20180730144647.GX24267@dhcp22.suse.cz> <20180730145425.GE1206094@devbig004.ftw2.facebook.com> <0018ac3b-94ee-5f09-e4e0-df53d2cbc925@i-love.sakura.ne.jp> <20180730154424.GG1206094@devbig004.ftw2.facebook.com> <20180730185110.GB24267@dhcp22.suse.cz> <20180730191005.GC24267@dhcp22.suse.cz> <6f433d59-4a56-b698-e119-682bb8bf6713@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6f433d59-4a56-b698-e119-682bb8bf6713@i-love.sakura.ne.jp> 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 31-07-18 06:01:48, Tetsuo Handa wrote: > On 2018/07/31 4:10, Michal Hocko wrote: > > Since should_reclaim_retry() should be a natural reschedule point, > > let's do the short sleep for PF_WQ_WORKER threads unconditionally in > > order to guarantee that other pending work items are started. This will > > workaround this problem and it is less fragile than hunting down when > > the sleep is missed. E.g. we used to have a sleeping point in the oom > > path but this has been removed recently because it caused other issues. > > Having a single sleeping point is more robust. > > linux.git has not removed the sleeping point in the OOM path yet. Since removing the > sleeping point in the OOM path can mitigate CVE-2016-10723, please do so immediately. is this an {Acked,Reviewed,Tested}-by? I will send the patch to Andrew if the patch is ok. > (And that change will conflict with Roman's cgroup aware OOM killer patchset. But it > should be easy to rebase.) That is still a WIP so I would lose sleep over it. -- Michal Hocko SUSE Labs