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From: Sasha Levin <Alexander.Levin@microsoft.com>
Subject: Re: [PATCH AUTOSEL for 4.15 019/189] printk: Add console owner and
 waiter logic to load balance console writes
Date: Sun, 15 Apr 2018 14:34:52 +0000
Message-ID: <20180415143447.GL2341@sasha-vm>
References: <20180409001637.162453-1-alexander.levin@microsoft.com>
 <20180409001637.162453-19-alexander.levin@microsoft.com>
 <20180409081535.dq7p5bfnpvd3xk3t@pathway.suse.cz>
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To: Petr Mladek <pmladek@suse.com>
Cc: "stable@vger.kernel.org" <stable@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "Steven
 Rostedt (VMware)" <rostedt@goodmis.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>, Michal Hocko <mhocko@kernel.org>, Vlastimil Babka <vbabka@suse.cz>, Peter Zijlstra <peterz@infradead.org>, Linus Torvalds <torvalds@linux-foundation.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>, Pavel Machek <pavel@ucw.cz>

On Mon, Apr 09, 2018 at 10:15:35AM +0200, Petr Mladek wrote:
>On Mon 2018-04-09 00:16:59, Sasha Levin wrote:
>> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>>
>> [ Upstream commit dbdda842fe96f8932bae554f0adf463c27c42bc7 ]
>>
>> This patch implements what I discussed in Kernel Summit. I added
>> lockdep annotation (hopefully correctly), and it hasn't had any splats
>> (since I fixed some bugs in the first iterations). It did catch
>> problems when I had the owner covering too much. But now that the owner
>> is only set when actively calling the consoles, lockdep has stayed
>> quiet.
>
>I do not think that this is a material for stable backports. Yes, it
>is a fix but it is not trivial. There are already 3 follow up commits:
>
>c162d5b4338d72deed6 ("printk: Hide console waiter logic into helpers")
>fd5f7cde1b85d4c8e09 ("printk: Never set console_may_schedule in
>		console_trylock()")
>c14376de3a1befa70d9 ("printk: Wake klogd when passing console_lock owner")
>
>One is just a code clean up but the other two are changes/fixes that
>should go together with Steven's patch.
>
>These changes tries to prevent softlockups. It is a problem that is
>being discussed for years. We are still waiting for feedback to see if
>more changes will be necessary. IMHO, there is no reason to hurry and
>backport it everywhere.
>
>Best Regards,
>Petr

I'll remove it, thanks Petr!=