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SubjectRe: WARNING: lock held when returning to user space!
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On 4/6/18 7:02 AM, syzbot wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> 38c23685b273cfb4ccf31a199feccce3bdcb5d83 (Fri Apr 6 04:29:35 2018 +0000)
> Merge tag 'armsoc-drivers' of
> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
>
> So far this crash happened 9 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6407930337296384
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=4942413340606464
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=4764483918495744
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-5813481738265533882
> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+31e8daa8b3fc129e75f2@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
>
>
> ================================================
> WARNING: lock held when returning to user space!
> 4.16.0+ #3 Not tainted
> ------------------------------------------------
> syzkaller433111/4462 is leaving the kernel with locks still held!
> 1 lock held by syzkaller433111/4462:
> #0: 0000000003a06fae (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x1ec0
> drivers/block/loop.c:1363

Is this a new regression? Omar did just fiddle with the locking a bit,
seems suspicious.

--
Jens Axboe

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