From: "Theodore Ts'o" <tytso@mit.edu>
To: syzbot <syzbot+4bfbbf28a2e50ab07368@syzkaller.appspotmail.com>
Cc: adilger.kernel@dilger.ca, davem@davemloft.net,
eladr@mellanox.com, idosch@mellanox.com, jiri@mellanox.com,
john.stultz@linaro.org, linux-ext4@vger.kernel.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com, tglx@linutronix.de
Subject: Re: INFO: rcu detected stall in ext4_write_checks
Date: Wed, 26 Jun 2019 14:42:51 -0400 [thread overview]
Message-ID: <20190626184251.GE3116@mit.edu> (raw)
In-Reply-To: <000000000000d3f34b058c3d5a4f@google.com>
On Wed, Jun 26, 2019 at 10:27:08AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: abf02e29 Merge tag 'pm-5.2-rc6' of git://git.kernel.org/pu..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1435aaf6a00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e5c77f8090a3b96b
> dashboard link: https://syzkaller.appspot.com/bug?extid=4bfbbf28a2e50ab07368
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11234c41a00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15d7f026a00000
>
> The bug was bisected to:
>
> commit 0c81ea5db25986fb2a704105db454a790c59709c
> Author: Elad Raz <eladr@mellanox.com>
> Date: Fri Oct 28 19:35:58 2016 +0000
>
> mlxsw: core: Add port type (Eth/IB) set API
Um, so this doesn't pass the laugh test.
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10393a89a00000
It looks like the automated bisection machinery got confused by two
failures getting triggered by the same repro; the symptoms changed
over time. Initially, the failure was:
crashed: INFO: rcu detected stall in {sys_sendfile64,ext4_file_write_iter}
Later, the failure changed to something completely different, and much
earlier (before the test was even started):
run #5: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor216456474" "root@10.128.15.205:./syz-executor216456474"]: exit status 1
Connection timed out during banner exchange
lost connection
Looks like an opportunity to improve the bisection engine?
- Ted
next prev parent reply other threads:[~2019-06-26 18:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 17:27 INFO: rcu detected stall in ext4_write_checks syzbot
2019-06-26 18:42 ` Theodore Ts'o [this message]
2019-06-26 21:03 ` Theodore Ts'o
2019-06-26 22:47 ` Theodore Ts'o
2019-07-05 13:24 ` Dmitry Vyukov
2019-07-05 15:16 ` Paul E. McKenney
2019-07-05 15:47 ` Amir Goldstein
2019-07-05 15:48 ` Dmitry Vyukov
2019-07-05 19:10 ` Paul E. McKenney
2019-07-06 4:28 ` Theodore Ts'o
2019-07-06 6:16 ` Paul E. McKenney
2019-07-06 15:02 ` Theodore Ts'o
2019-07-06 18:03 ` Paul E. McKenney
2019-07-07 1:16 ` Paul E. McKenney
2019-07-14 14:48 ` Dmitry Vyukov
2019-07-14 18:49 ` Paul E. McKenney
2019-07-15 13:29 ` Peter Zijlstra
2019-07-15 13:33 ` Dmitry Vyukov
2019-07-15 13:46 ` Peter Zijlstra
2019-07-15 14:02 ` Paul E. McKenney
2019-07-22 10:03 ` Dmitry Vyukov
2019-07-23 8:51 ` Dmitry Vyukov
2019-07-14 19:05 ` Theodore Ts'o
2019-07-14 19:29 ` Paul E. McKenney
2019-07-15 3:10 ` Paul E. McKenney
2019-07-15 13:01 ` Paul E. McKenney
2019-07-15 13:29 ` Dmitry Vyukov
2019-07-15 13:39 ` Peter Zijlstra
2019-07-15 14:03 ` Paul E. McKenney
2019-07-15 13:22 ` Peter Zijlstra
2019-07-05 13:18 ` Dmitry Vyukov
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