From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id 9F2D96B000D for ; Fri, 3 Aug 2018 02:16:56 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id t10-v6so1468051eds.7 for ; Thu, 02 Aug 2018 23:16:56 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id d61-v6si3137604edd.124.2018.08.02.23.16.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 02 Aug 2018 23:16:55 -0700 (PDT) Date: Fri, 3 Aug 2018 08:16:53 +0200 From: Michal Hocko Subject: Re: [PATCH] mm,page_alloc: PF_WQ_WORKER threads must sleep at should_reclaim_retry(). Message-ID: <20180803061653.GB27245@dhcp22.suse.cz> References: <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> <20180731050928.GA4557@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: Tejun Heo , Roman Gushchin , Johannes Weiner , Vladimir Davydov , David Rientjes , Andrew Morton , Linus Torvalds , linux-mm , LKML On Fri 03-08-18 07:05:54, Tetsuo Handa wrote: > On 2018/07/31 14:09, Michal Hocko wrote: > > 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. > > > > Now that Roman's cgroup aware OOM killer patchset will be dropped from linux-next.git , > linux-next.git will get the sleeping point removed. Please send this patch to linux-next.git . I still haven't heard any explicit confirmation that the patch works for your workload. Should I beg for it? Or you simply do not want to have your stamp on the patch? If yes, I can live with that but this playing hide and catch is not really a lot of fun. -- Michal Hocko SUSE Labs