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From: Sasha Levin <Alexander.Levin@microsoft.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>, Greg KH <greg@kroah.com>,
	Pavel Machek <pavel@ucw.cz>, Steven Rostedt <rostedt@goodmis.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Peter Zijlstra <peterz@infradead.org>, Jan Kara <jack@suse.cz>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Byungchul Park <byungchul.park@lge.com>,
	Tejun Heo <tj@kernel.org>
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	[thread overview]
Message-ID: <20180417143641.GV2341@sasha-vm> (raw)
In-Reply-To: <20180417142246.GH17484@dhcp22.suse.cz>

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/commit/?id=c61611f70958d86f659bca25c02ae69413747a8d
>
>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.
>-- 
>Michal Hocko
>SUSE Labs

  reply	other threads:[~2018-04-17 14:36 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20180409001936.162706-1-alexander.levin@microsoft.com>
2018-04-09  0:19 ` [PATCH AUTOSEL for 4.14 015/161] printk: Add console owner and waiter logic to load balance console writes Sasha Levin
2018-04-09  8:22   ` Petr Mladek
2018-04-15 14:42     ` Sasha Levin
2018-04-16 13:30       ` Steven Rostedt
2018-04-16 15:18         ` Linus Torvalds
2018-04-16 15:30           ` Pavel Machek
2018-04-16 15:50             ` Sasha Levin
2018-04-16 16:06               ` Pavel Machek
2018-04-16 16:14                 ` Sasha Levin
2018-04-16 16:22                   ` Steven Rostedt
2018-04-16 16:31                     ` Sasha Levin
2018-04-16 16:47                       ` Steven Rostedt
2018-04-16 16:53                         ` Sasha Levin
2018-04-16 17:00                           ` Pavel Machek
2018-04-17 10:46                             ` Greg KH
2018-04-17 12:24                               ` Petr Mladek
2018-04-17 12:49                                 ` Michal Hocko
2018-04-17 13:39                                   ` Sasha Levin
2018-04-17 14:22                                     ` Michal Hocko
2018-04-17 14:36                                       ` Sasha Levin [this message]
2018-04-17 18:10                                         ` Michal Hocko
2018-04-17 13:45                                 ` Sasha Levin
2018-04-18  8:33                                   ` Petr Mladek
2018-04-16 16:28                   ` Pavel Machek
2018-04-16 16:39                     ` Sasha Levin
2018-04-16 16:42                       ` Pavel Machek
2018-04-16 16:45                         ` Sasha Levin
2018-04-16 16:54                           ` Pavel Machek
2018-04-17 10:50                             ` Greg KH
2018-04-16 17:05                   ` Pavel Machek
2018-04-16 17:16                     ` Sasha Levin
2018-04-16 17:44                       ` Steven Rostedt
2018-04-16 18:17                         ` Sasha Levin
2018-04-16 18:35                           ` Steven Rostedt
2018-04-16 20:17                       ` Jiri Kosina
2018-04-16 20:36                         ` Sasha Levin
2018-04-16 20:43                           ` Jiri Kosina
2018-04-16 21:18                             ` Sasha Levin
2018-04-16 21:28                               ` Jiri Kosina
2018-04-17 10:39                                 ` Greg KH
2018-04-17 11:07                                   ` Michal Hocko
2018-04-17 14:04                                     ` Sasha Levin
2018-04-17 14:15                                       ` Steven Rostedt
2018-04-17 14:36                                         ` Greg KH
2018-04-17 14:36                                       ` Michal Hocko
2018-04-17 14:55                                         ` Sasha Levin
2018-04-17 15:52                                           ` Jiri Kosina
2018-04-17 16:06                                             ` Sasha Levin
2018-05-03 10:04                                               ` Pavel Machek
2018-05-03 13:02                                                 ` Sasha Levin
2018-04-17 16:25                                             ` Mike Galbraith
2018-04-17 11:21                                   ` Jiri Kosina
2018-05-03  9:47                               ` Pavel Machek
2018-05-03 13:06                                 ` Sasha Levin
2018-04-16 16:20                 ` Steven Rostedt
2018-04-16 16:28                   ` Sasha Levin
2018-04-16 16:39                     ` Pavel Machek
2018-04-16 16:43                       ` Sasha Levin
2018-04-16 16:53                         ` Steven Rostedt
2018-04-16 16:58                           ` Pavel Machek
2018-04-16 17:09                           ` Sasha Levin
2018-04-16 17:33                             ` Steven Rostedt
2018-04-16 17:42                               ` Sasha Levin
2018-04-16 18:26                                 ` Steven Rostedt
2018-04-16 18:30                                   ` Linus Torvalds
2018-04-16 18:41                                     ` Steven Rostedt
2018-04-16 18:52                                       ` Linus Torvalds
2018-04-16 19:00                                         ` Linus Torvalds
2018-04-16 19:30                                           ` Steven Rostedt
2018-04-16 19:19                                         ` Linus Torvalds
2018-04-16 19:24                                         ` Steven Rostedt
2018-04-16 19:28                                           ` Linus Torvalds
2018-04-16 19:31                                             ` Linus Torvalds
2018-04-16 19:58                                               ` Steven Rostedt
2018-04-16 19:38                                             ` Steven Rostedt
2018-04-16 19:55                                               ` Linus Torvalds
2018-04-16 20:02                                                 ` Steven Rostedt
2018-04-16 20:17                                                   ` Linus Torvalds
2018-04-16 20:33                                                     ` Jiri Kosina
2018-04-16 21:27                                                     ` Steven Rostedt
2018-04-16 18:35                                   ` Sasha Levin
2018-04-16 18:57                                     ` Steven Rostedt
2018-04-16 15:36           ` Steven Rostedt
2018-04-16 16:02             ` Sasha Levin
2018-04-16 16:10               ` Pavel Machek
2018-04-16 16:12               ` Steven Rostedt
2018-04-16 16:19                 ` Sasha Levin
2018-04-16 16:30                   ` Steven Rostedt
2018-04-16 16:37                     ` Sasha Levin
2018-04-16 17:06                       ` Pavel Machek
2018-04-16 17:23                         ` Sasha Levin
2018-04-17 11:41                           ` Jan Kara
2018-04-17 13:31                             ` Sasha Levin
2018-04-17 15:55                               ` Jan Kara
2018-04-17 16:19                                 ` Sasha Levin
2018-04-17 17:57                                   ` Jan Kara
2018-04-17 18:28                                     ` Sasha Levin
2018-05-03  9:36                                   ` Pavel Machek
2018-05-03 13:28                                     ` Sasha Levin
2018-05-03  9:32                           ` Pavel Machek
2018-05-03 13:30                             ` Sasha Levin
2018-04-19 11:41                   ` Thomas Backlund
2018-04-19 13:59                     ` Greg KH
2018-04-19 14:05                       ` Jan Kara
2018-04-19 14:22                         ` Greg KH
2018-04-19 15:16                           ` Thomas Backlund
2018-04-19 15:57                             ` Greg KH
2018-04-19 16:25                               ` Thomas Backlund
2018-04-19 16:41                           ` Greg KH
2018-04-19 15:04                       ` Thomas Backlund
2018-04-19 15:09                         ` Sasha Levin
2018-04-19 16:20                           ` Thomas Backlund
2018-04-16 15:39           ` Sasha Levin

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