Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load
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.
Regards,
Salvatore
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