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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: ebiggers3@gmail.com,
	bot+e38be687a2450270a3b593bacb6b5795a7a74edb@syzkaller.appspotmail.com,
	peter@hurleysoftware.com
Cc: dvyukov@google.com, gregkh@linuxfoundation.org,
	kstewart@linuxfoundation.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, pombredanne@nexb.com,
	syzkaller-bugs@googlegroups.com, tglx@linutronix.de
Subject: Re: BUG: workqueue lockup (2)
Date: Sun, 13 May 2018 11:06:17 +0900	[thread overview]
Message-ID: <201805131106.GFF73973.OOtMVQFSFOJFHL@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20180512215222.GC817@sol.localdomain>

Eric Biggers wrote:
> The bug that this reproducer reproduces was fixed a while ago by commit
> 966031f340185e, so I'm marking this bug report fixed by it:
> 
> #syz fix: n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD)

Nope. Commit 966031f340185edd ("n_tty: fix EXTPROC vs ICANON interaction with
TIOCINQ (aka FIONREAD)") is "Wed Dec 20 17:57:06 2017 -0800" but the last
occurrence on linux.git (commit 008464a9360e31b1 ("Merge branch 'for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid")) is only a few days ago
("Wed May 9 10:49:52 2018 -1000").

> 
> Note that the error message was not always "BUG: workqueue lockup"; it was also
> sometimes like "watchdog: BUG: soft lockup - CPU#5 stuck for 22s!".
> 
> syzbot still is hitting the "BUG: workqueue lockup" error sometimes, but it must
> be for other reasons.  None has a reproducer currently.

The last occurrence on linux.git is considered as a duplicate of

  [upstream] INFO: rcu detected stall in n_tty_receive_char_special
  https://syzkaller.appspot.com/bug?id=3d7481a346958d9469bebbeb0537d5f056bdd6e8

which we already have a reproducer at
https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/YCVPocx3AgAJ
and debug output is available at
https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/TxQ7WS5ZAwAJ .

We are currently waiting for comments from Peter Hurley who added that code.

  reply	other threads:[~2018-05-13  2:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-03 14:31 syzbot
2017-12-03 14:36 ` Dmitry Vyukov
2017-12-03 14:48   ` Thomas Gleixner
2017-12-04 11:08     ` Tetsuo Handa
2017-12-19 12:25 ` syzbot
2017-12-19 14:27   ` Tetsuo Handa
2017-12-19 14:40     ` Dmitry Vyukov
2017-12-19 16:37       ` Dmitry Vyukov
2017-12-20 10:55         ` Tetsuo Handa
2017-12-21 10:19           ` Dmitry Vyukov
2017-12-21 10:22           ` Dmitry Vyukov
2017-12-21 11:04           ` Dmitry Vyukov
2017-12-21 13:07             ` Tetsuo Handa
2017-12-28 13:43               ` Dmitry Vyukov
2018-05-12 21:52   ` Eric Biggers
2018-05-13  2:06     ` Tetsuo Handa [this message]
2018-05-13  3:32       ` Eric Biggers
2018-05-13 14:29         ` Tetsuo Handa
2018-05-13 14:35           ` Dmitry Vyukov

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