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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Petr Mladek <pmladek@suse.com>, Jiri Kosina <jikos@kernel.org>
Cc: Amir Goldstein <amir73il@gmail.com>,
	syzbot+6fb572170402d311dd39@syzkaller.appspotmail.com,
	Jan Kara <jack@suse.cz>,
	syzkaller-bugs@googlegroups.com,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: INFO: task hung in fsnotify_connector_destroy_workfn (2)
Date: Tue, 25 Sep 2018 21:30:26 +0900	[thread overview]
Message-ID: <19a86705-308f-17af-f5d2-9abb150d2bdb@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20180925085506.ddzq42ci4ul3voxm@pathway.suse.cz>

On 2018/09/25 17:55, Petr Mladek wrote:
>> I guess the patch below fixes it, however the kworker should not really be 
>> blocked by this I think ... adding a few more printk folks to double-check 
>> why the kworker would get stuck due to massive printk() flood.
> 
> It seems that the many printk() calls just delay the entire
> process and rcu gets blocked for too long. The messages are
> the same all the time. So some rate limiting looks like
> a reasonable solution.
> 

Yes. Commit 128f380410350012 ("android: binder: Rate-limit debug and userspace triggered err msgs")
chose ratelimiting as a fix for https://syzkaller.appspot.com/bug?id=0e75779a6f0faac461510c6330514e8f0e893038 .

Since syzbot did not reproduce the problem with Jiri's patch applied,
I think we can apply Jiri's patch as a fix for this problem.

      reply	other threads:[~2018-09-25 18:38 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-15  2:33 INFO: task hung in fsnotify_connector_destroy_workfn (2) syzbot
2018-09-15 16:42 ` Amir Goldstein
2018-09-15 17:25 ` Tetsuo Handa
2018-09-15 23:05   ` Amir Goldstein
2018-09-24 13:19     ` Jiri Kosina
2018-09-24 13:31       ` Dmitry Vyukov
2018-09-24 14:03         ` Tetsuo Handa
2018-09-25  8:55       ` Petr Mladek
2018-09-25 12:30         ` Tetsuo Handa [this message]

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