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Subject: Re: INFO: task hung in grab_super
To:     Dmitry Vyukov <dvyukov@google.com>,
        Eric Van Hensbergen <ericvh@gmail.com>,
        Ron Minnich <rminnich@sandia.gov>,
        Latchesar Ionkov <lucho@ionkov.net>,
        v9fs-developer@lists.sourceforge.net
Cc:     syzbot <syzbot+f425456ea8aa16b40d20@syzkaller.appspotmail.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Al Viro <viro@zeniv.linux.org.uk>
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 <CACT4Y+bM1tfisT+7=ZChHRZKZkddbWp0kNi5q46EqOYBSptXtg@mail.gmail.com>
From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Message-ID: <0adc592b-d4a3-f6da-3c5c-22490f641eb9@i-love.sakura.ne.jp>
Date:   Wed, 18 Jul 2018 21:53:28 +0900
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On 2018/07/18 20:41, Dmitry Vyukov wrote:
> This seems to be related to 9p. After rerunning the log I got:
> 
> root@syzkaller:~# ps afxu | grep syz
> root     18253  0.0  0.0      0     0 ttyS0    Zl   10:16   0:00  \_
> [syz-executor] <defunct>
> root@syzkaller:~# cat /proc/18253/task/*/stack
> [<0>] p9_client_rpc+0x3a2/0x1400
> [<0>] p9_client_flush+0x134/0x2a0
> [<0>] p9_client_rpc+0x122c/0x1400
> [<0>] p9_client_create+0xc56/0x16af
> [<0>] v9fs_session_init+0x21a/0x1a80
> [<0>] v9fs_mount+0x7c/0x900
> [<0>] mount_fs+0xae/0x328
> [<0>] vfs_kern_mount.part.34+0xdc/0x4e0
> [<0>] do_mount+0x581/0x30e0
> [<0>] ksys_mount+0x12d/0x140
> [<0>] __x64_sys_mount+0xbe/0x150
> [<0>] do_syscall_64+0x1b9/0x820
> [<0>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [<0>] 0xffffffffffffffff
> 
> There is a bunch of hangs in 9p, so let's do:
> 
> #syz dup: INFO: task hung in flush_work
> 
Then, is dumping all threads when khungtaskd fires a candidate
for CONFIG_DEBUG_AID_FOR_SYZBOT=y path?