Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load
Hi Dirk,
On Sun, Aug 02, 2020 at 03:44:09PM +0200, Salvatore Bonaccorso wrote:
> Control: tags -1 + moreinfo
>
> Hi Dirk
>
> On Sun, Aug 02, 2020 at 10:00:27AM +0200, Dirk Kostrewa wrote:
> > Package: src:linux
> > Version: 4.19.132-1
> > Severity: normal
> >
> > Dear Maintainer,
> >
> > after booting the kernel 4.19.0-10-amd64, there is a kworker process running
> > with a permanent high CPU load of almost 90% as reported by the "top"
> > command:
> >
> > $ top
> > top - 09:48:19 up 0 min, 4 users, load average: 1.91, 0.58, 0.20
> > Tasks: 218 total, 2 running, 216 sleeping, 0 stopped, 0 zombie
> > %Cpu(s): 0.8 us, 12.4 sy, 0.0 ni, 84.5 id, 0.0 wa, 0.0 hi, 2.3 si, 0.0
> > st
> > MiB Mem : 15889.4 total, 14173.1 free, 889.3 used, 827.0 buff/cache
> > MiB Swap: 0.0 total, 0.0 free, 0.0 used. 14677.7 avail Mem
> >
> > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> > 64 root 20 0 0 0 0 R 86.7 0.0 0:47.41
> > kworker/0:2+pm
> > 9 root 20 0 0 0 0 S 20.0 0.0 0:08.84
> > ksoftirqd/0
> > 364 root -51 0 0 0 0 S 6.7 0.0 0:00.50
> > irq/126-nvidia
> > 1177 dirk 20 0 2921696 122848 94268 S 6.7 0.8 0:02.23 kwin_x11
> > 1 root 20 0 169652 10280 7740 S 0.0 0.1 0:01.56 systemd
> > 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
> > ...
> >
> > The expected result after booting the kernel 4.19.0-10-amd64 is a kworker
> > process with a CPU load close to 0%.
> >
> > As a control, booting the previous kernel 4.19.0-9-amd64 does not show a
> > high CPU load for the kworker process. Instead, the kworker CPU load
> > reported by the "top" command is 0.0%.
> >
> > Therefore, I suspect a bug in the kernel 4.19.0-10-amd64.
> >
> > Neither "dmesg" nor "journalctl -b" show any messages containing "kworker".
> >
> > I am using Debian/GNU Linux 10.5 with kernel 4.19.0-10-amd64 and libc6:amd64
> > 2.28-10.
> >
> > If you need more information, I would be happy to provide it.
>
> To find out what could be the cause, could you have a look at
> https://www.kernel.org/doc/html/latest/core-api/workqueue.html#debugging
> this could help determining isolating why the kworker goes crazy.
Please as well to the above one additional thing: Can you reproduce
the issue when the kernel does not get tained? So without loading the
propriertary, out-of-tree modules.
This is particularly important if the issue can be tracked down, found
in upstream and needs to be reported upstream.
Regards,
Salvatore
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