From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 148D86B0271 for ; Tue, 17 Apr 2018 10:36:49 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id u11-v6so12455393pls.22 for ; Tue, 17 Apr 2018 07:36:49 -0700 (PDT) Received: from NAM02-CY1-obe.outbound.protection.outlook.com (mail-cys01nam02on0126.outbound.protection.outlook.com. [104.47.37.126]) by mx.google.com with ESMTPS id u12-v6si11170995plm.83.2018.04.17.07.36.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 17 Apr 2018 07:36:47 -0700 (PDT) From: Sasha Levin Subject: Re: [PATCH AUTOSEL for 4.14 015/161] printk: Add console owner and waiter logic to load balance console writes Date: Tue, 17 Apr 2018 14:36:44 +0000 Message-ID: <20180417143641.GV2341@sasha-vm> References: <20180416122244.146aec48@gandalf.local.home> <20180416163107.GC2341@sasha-vm> <20180416124711.048f1858@gandalf.local.home> <20180416165258.GH2341@sasha-vm> <20180416170010.GA11034@amd> <20180417104637.GD8445@kroah.com> <20180417122454.rwkwpsfvyhpzvvx3@pathway.suse.cz> <20180417124924.GE17484@dhcp22.suse.cz> <20180417133931.GS2341@sasha-vm> <20180417142246.GH17484@dhcp22.suse.cz> In-Reply-To: <20180417142246.GH17484@dhcp22.suse.cz> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Petr Mladek , Greg KH , Pavel Machek , Steven Rostedt , Linus Torvalds , "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Vlastimil Babka , Peter Zijlstra , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , Byungchul Park , Tejun Heo On Tue, Apr 17, 2018 at 04:22:46PM +0200, Michal Hocko wrote: >On Tue 17-04-18 13:39:33, Sasha Levin wrote: >[...] >> But mm/ commits don't come only from these people. Here's a concrete >> example we can discuss: >> >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi= t/?id=3Dc61611f70958d86f659bca25c02ae69413747a8d > >I would be really careful. Because that reqiures to audit all callers to >be compliant with the change. This is just _too_ easy to backport >without noticing a failure. Now consider the other side. Is there any >real bug report backing this? This behavior was like that for quite some >time but I do not remember any actual bug report and the changelog >doesn't mention one either. It is about theoretical problem. https://lkml.org/lkml/2018/3/19/430 There's even a fun little reproducer that allowed me to confirm it's an issue (at least) on 4.15. Heck, it might even qualify as a CVE. >So if this was to be merged to stable then the changelog should contain >a big fat warning about the existing users and how they should be >checked. So what I'm asking is why *wasn't* it sent to stable? Yes, it requires additional work backporting this, but what I'm saying is that this didn't happen at all. >Besides that I can see Reviewed-by: akpm and Andrew is usually very >careful about stable backports so there probably _was_ a reson to >exclude stable. >--=20 >Michal Hocko >SUSE Labs=