linux-kernel - Re: WARNING: bad unlock balance in xfs

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Date:   Wed, 9 May 2018 16:13:57 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     "Theodore Y. Ts'o" <tytso@....edu>,
        Dave Chinner <david@...morbit.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        syzbot <syzbot+84a67953651a971809ba@...kaller.appspotmail.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-xfs@...r.kernel.org,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: WARNING: bad unlock balance in xfs_iunlock

On Wed, May 9, 2018 at 3:55 PM, Theodore Y. Ts'o <tytso@....edu> wrote:
>>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5719304272084992
>>>> syzkaller reproducer:
>>>> https://syzkaller.appspot.com/x/repro.syz?id=5767783983874048
>>>
>>> What a mess. A hand built, hopelessly broken filesystem image made
>>> up of hex dumps, written into a mmap()d region of memory, then
>>> copied into a tmpfs file and mounted with the loop device.
>>>
>>> Engineers that can debug broken filesystems don't grow on trees.  If
>>> we are to have any hope of understanding what the hell this test is
>>> doing, the bot needs to supply us with a copy of the built
>>> filesystem image the test uses. We need to be able to point forensic
>>> tools at the image to decode all the structures into human readable
>>> format - if we are forced to do that by hand or jump through hoops
>>> to create our own filesystem image than I'm certainly not going to
>>> waste time looking at these reports...
>>
>> Hi Dave,
>>
>> Here is the image:
>> https://drive.google.com/file/d/1jzhGGe5SBJcqfsjxCLHoh4Kazke1oTfC/view
>
> A suggestion --- insteading of forcing human beings --- either
> overworked file system developers, or understaffed fuzzing tool teams,
> to have to manually pull out the file system image out from the C
> repro, if it's too hard to add a link where the file system iamge can
> be downloaded from the Syzkaller web application --- how about adding
> an option to the C repro template which causes it to dump the image to
> a file and then immediately exit?

Hi Ted,

That's what I proposed above:
https://groups.google.com/d/msg/syzkaller-bugs/KJNNTgTdg_g/NRxarDcYBgAJ
But I did not get response yet.