BUG: workqueue lockup (4)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c1d84a1b42ef Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c5f491400000
kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
dashboard link: https://syzkaller.appspot.com/bug?extid=08116743f8ad6f9a6de7
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14514a6e400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1025ebb9400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+081167...@syzkaller.appspotmail.com

BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 204s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256
in-flight: 14:rtc_timer_do_work
pending: vmstat_shepherd, cache_reap, check_corruption
workqueue events_power_efficient: flags=0x80
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
pending: do_cache_clean
workqueue mm_percpu_wq: flags=0x8
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
pending: vmstat_update
workqueue kacpi_notify: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
pending: acpi_os_execute_deferred
pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=204s workers=2 idle: 2683


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[Dmitry Vyukov]

On Sun, Oct 7, 2018 at 2:15 PM, syzbot
<syzbot+081167...@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: c1d84a1b42ef Merge git://git.kernel.org/pub/scm/linux/kern..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14c5f491400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
> dashboard link: https://syzkaller.appspot.com/bug?extid=08116743f8ad6f9a6de7
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14514a6e400000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1025ebb9400000

The reproducer seems to be all about rtc. So +rtc maintainers.

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[Alexandre Belloni]

Hi,

On 07/10/2018 14:18:31+0200, Dmitry Vyukov wrote:
> On Sun, Oct 7, 2018 at 2:15 PM, syzbot
> <syzbot+081167...@syzkaller.appspotmail.com> wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: c1d84a1b42ef Merge git://git.kernel.org/pub/scm/linux/kern..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14c5f491400000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
> > dashboard link: https://syzkaller.appspot.com/bug?extid=08116743f8ad6f9a6de7
> > compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14514a6e400000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1025ebb9400000
>
> The reproducer seems to be all about rtc. So +rtc maintainers.
>

It seems to be that bug:
http://patchwork.ozlabs.org/patch/898552/

I'm pretty sure the fix is not correct though and didn't have the time
to work on a proper fix.

--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Eric Biggers]

Is there any plan to actually fix this? Because this bug is still open, syzbot
isn't able to report "workqueue lockup" bugs elsewhere in the kernel.

- Eric

[Alexandre Belloni]

This is still on my radar.