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

From	Salvatore Bonaccorso <carnil@debian.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load
Date	2020-08-29 11:40 +0200
Message-ID	<AJ5v3-2ic-11@gated-at.bofh.it> (permalink)
References	(7 earlier) <AD1kt-1I5-5@gated-at.bofh.it> <AINHQ-8h7-1@gated-at.bofh.it> <AJ523-27Q-5@gated-at.bofh.it> <Azhe9-3wS-5@gated-at.bofh.it> <AJ523-27Q-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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Hi Dirk,

Thanks for testing that.

On Sat, Aug 29, 2020 at 11:04:43AM +0200, Dirk Kostrewa wrote:
> Hi Salvatore,
> 
> I have enabled the verbose debugging mode on the command line and have
> appended the first 5000 lines of the dmesg output to this e-mail, running
> the current kernel from the Buster backports with the two kworker processes
> with high CPU load present.
> 
> After that, I have applied your patch to this kernel and rebooted with the
> patched kernel:
> 
> 5.7.0-0.bpo.2-amd64 #1 SMP Debian 5.7.10-1~bpo10+1a~test (2020-08-28) x86_64
> GNU/Linux
> 
> With your patch applied, the two kworker processes with high CPU load
> completely disappeared!

Unfortunately I suspect this indicates either a HW fault or a HW
design error as stated in the found kernel-thread which was just
uncovered by the mentioned kernel fix (which we temporarily reverted
with the patch). I can try to ask Alan Stern.

There might be a workaround workarble for you, the issue should
disapear if you prevent the system to automatically try to suspend
usb2 root hub (but you have the same on usb1 root hub).

# echo on >/sys/bus/usb/devices/usb2/power/control

will do that for the usb2 root hub.

Regards,
Salvatore

Thread

Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-02 15:50 +0200
  Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-02 18:30 +0200
    Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-11 21:30 +0200
      Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Dirk Kostrewa <dirk.kostrewa@mailbox.org> - 2020-08-12 13:10 +0200
        Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Dirk Kostrewa <dirk.kostrewa@mailbox.org> - 2020-08-12 18:00 +0200
          Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-12 18:10 +0200
            Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Dirk Kostrewa <dirk.kostrewa@mailbox.org> - 2020-08-13 11:00 +0200
            Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Dirk Kostrewa <dirk.kostrewa@mailbox.org> - 2020-08-21 11:40 +0200
          Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-28 16:40 +0200
            Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-08-29 11:40 +0200
              Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Dirk Kostrewa <dirk.kostrewa@mailbox.org> - 2020-09-04 18:00 +0200
                Bug#966703: linux-image-4.19.0-10-amd64: kworker process with permanent high CPU load Salvatore Bonaccorso <carnil@debian.org> - 2020-09-04 19:20 +0200

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