Re: INFO: task hung in fb_release

Dmitry Vyukov
2020-01-07T16:02:10Z

On Tue, Jan 7, 2020 at 4:48 PM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Mon, Dec 23, 2019 at 02:31:01AM -0800, syzbot wrote:
> > syzbot has bisected this bug to:
> >
> > commit e3933f26b657c341055443103bad331f4537b113
> > Author: Rex Zhu <Rex.Zhu@amd.com>
> > Date: Tue Jan 16 10:35:15 2018 +0000
> >
> > drm/amd/pp: Add edit/commit/show OD clock/voltage support in sysfs
>
> Pretty sure you don't even have that driver loaded ... from the config:
>
> # CONFIG_DRM_AMDGPU is not set
>
> :-)

Yes, it seems the bug is very flaky and flakiness changes over time.
And this is combined with non-deterministic kernel build bug:
https://github.com/google/syzkaller/issues/1271#issuecomment-559093018
It builds the same kernel, but gets a different result, so it's like
"nope, this commit very much affects the kernel so could be the root
cause"...

> Cheers, Daniel
> >
> > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12b5a799e00000
> > start commit: c6017471 Merge tag 'xfs-5.5-fixes-2' of git://git.kernel.o..
> > git tree: upstream
> > final crash: https://syzkaller.appspot.com/x/report.txt?x=11b5a799e00000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=16b5a799e00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=7f6119e2e3675a73
> > dashboard link: https://syzkaller.appspot.com/bug?extid=d130c4a0890561cfac5b
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=169b1925e00000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b9623ee00000
> >
> > Reported-by: syzbot+d130c4a0890561cfac5b@syzkaller.appspotmail.com
> > Fixes: e3933f26b657 ("drm/amd/pp: Add edit/commit/show OD clock/voltage
> > support in sysfs")
> >
> > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
>
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