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 85F4F6B000A for ; Tue, 31 Jul 2018 07:15:22 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id y8-v6so749321edr.12 for ; Tue, 31 Jul 2018 04:15:22 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id d61-v6si407684edd.124.2018.07.31.04.15.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 31 Jul 2018 04:15:21 -0700 (PDT) Date: Tue, 31 Jul 2018 13:15:19 +0200 From: Michal Hocko Subject: Re: [PATCH] mm,page_alloc: PF_WQ_WORKER threads must sleep at should_reclaim_retry(). Message-ID: <20180731111519.GH4557@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 Tue 31-07-18 19:47:45, 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'm saying that "we used to have a sleeping point in the oom path but this has been > removed recently" is not true. You need to send that patch to linux.git first if you > want to refer that patch in this patch. That patch is already sitting in mmotm tree and this one will go on top. I do not really see any reason to rush it to Linus tree. A dubious CVE doesn't really raise the priority if you ask me. On the other hand, having a confirmation, either of the above tags would help to raise the credibility of the change. > > I will send the patch to Andrew if the patch is ok. > > Andrew, can we send the "we used to have a sleeping point in the oom path but this has > been removed recently" patch to linux.git ? This can really wait for the next merge window IMHO. -- Michal Hocko SUSE Labs