From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Daniel Wang <wonderfly@google.com>
Cc: stable@vger.kernel.org, pmladek@suse.com,
Alexander.Levin@microsoft.com, akpm@linux-foundation.org,
byungchul.park@lge.com, dave.hansen@intel.com,
hannes@cmpxchg.org, jack@suse.cz, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, mathieu.desnoyers@efficios.com,
mgorman@suse.de, mhocko@kernel.org, pavel@ucw.cz,
penguin-kernel@i-love.sakura.ne.jp, peterz@infradead.org,
rostedt@goodmis.org, tj@kernel.org,
torvalds@linux-foundation.org, vbabka@suse.cz,
xiyou.wangcong@gmail.com, pfeiner@google.com
Subject: Re: 4.14 backport request for dbdda842fe96f: "printk: Add console owner and waiter logic to load balance console writes"
Date: Tue, 2 Oct 2018 17:16:53 +0900 [thread overview]
Message-ID: <20181002081653.GJ598@jagdpanzerIV> (raw)
In-Reply-To: <20180927194601.207765-1-wonderfly@google.com>
On (09/27/18 12:46), Daniel Wang wrote:
> Prior to this change, the combination of `softlockup_panic=1` and
> `softlockup_all_cpu_stacktrace=1` may result in a deadlock when the reboot path
> is trying to grab the console lock that is held by the stack trace printing
> path. What seems to be happening is that while there are multiple CPUs, only one
> of them is tasked to print the back trace of all CPUs. On a machine with many
> CPUs and a slow serial console (on Google Compute Engine for example), the stack
> trace printing routine hits a timeout and the reboot path kicks in. The latter
> then tries to print something else, but can't get the lock because it's still
> held by earlier printing path.
Sorry, I'm missing something here. Steven's patch deals with lockups and
I understand why you want to backport the patch set; but console output
deadlock on panic() is another thing.
You said
"then tries to print something else, but can't get the lock
because it's still held by earlier printing path"
Can't get which of the locks?
-ss
prev parent reply other threads:[~2018-10-02 8:17 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 19:46 4.14 backport request for dbdda842fe96f: "printk: Add console owner and waiter logic to load balance console writes" Daniel Wang
2018-10-01 19:23 ` Steven Rostedt
2018-10-01 20:13 ` Pavel Machek
2018-10-01 20:21 ` Vlastimil Babka
2018-10-01 20:38 ` Daniel Wang
2018-10-01 20:29 ` Steven Rostedt
2018-10-01 20:37 ` Daniel Wang
2018-10-01 20:40 ` Sasha Levin
2018-10-02 8:42 ` Petr Mladek
2018-10-02 17:21 ` Daniel Wang
2018-10-03 0:15 ` Daniel Wang
2018-10-03 1:23 ` Steven Rostedt
2018-10-03 9:14 ` Petr Mladek
2018-10-03 17:16 ` Daniel Wang
2018-10-03 17:37 ` Steven Rostedt
2018-10-03 18:37 ` Daniel Wang
2018-10-03 23:37 ` Daniel Wang
2018-10-04 7:44 ` Sergey Senozhatsky
2018-10-04 8:05 ` Sergey Senozhatsky
2018-10-04 8:36 ` Petr Mladek
2018-10-04 8:55 ` Sergey Senozhatsky
2018-10-21 18:09 ` Daniel Wang
2018-10-22 9:32 ` Petr Mladek
2018-10-22 10:09 ` Sergey Senozhatsky
2018-11-01 16:05 ` Daniel Wang
2018-11-09 6:47 ` Sergey Senozhatsky
2018-12-12 1:16 ` Daniel Wang
2018-12-12 5:21 ` Sergey Senozhatsky
2018-12-12 6:08 ` Daniel Wang
2018-12-12 6:28 ` Sergey Senozhatsky
2018-12-12 6:48 ` Sasha Levin
2018-12-12 8:10 ` Sergey Senozhatsky
2018-12-12 13:36 ` Petr Mladek
2018-12-12 13:59 ` Sergey Senozhatsky
2018-12-12 17:43 ` Sasha Levin
2018-12-12 20:11 ` Daniel Wang
2018-12-12 21:43 ` Sasha Levin
2018-12-12 21:49 ` Daniel Wang
2018-12-12 21:52 ` Sasha Levin
2018-12-12 21:56 ` Daniel Wang
2018-12-13 0:40 ` Daniel Wang
2018-12-13 2:27 ` Sergey Senozhatsky
2018-12-13 2:39 ` Daniel Wang
2018-12-13 9:59 ` Petr Mladek
2018-12-13 14:29 ` Sasha Levin
2018-12-13 2:07 ` Sergey Senozhatsky
2018-12-28 0:16 ` Sergey Senozhatsky
2018-12-28 8:27 ` Greg KH
2018-12-28 22:03 ` Daniel Wang
2018-12-28 22:03 ` Daniel Wang
2018-12-30 3:03 ` Sergey Senozhatsky
2018-10-04 7:49 ` Petr Mladek
2018-10-02 8:16 ` Sergey Senozhatsky [this message]
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