Bug 1225881

Summary:	Whole system hangs up / freezes when Input switched on external monitor on Thinkpad T14 G2 AMD with Ultra Dock
Product:	[openSUSE] openSUSE Tumbleweed	Reporter:	Uberrice <suse>
Component:	Kernel	Assignee:	openSUSE Kernel Bugs <kernel-bugs>
Status:	RESOLVED FIXED	QA Contact:	E-mail List <qa-bugs>
Severity:	Critical
Priority:	P5 - None	CC:	fvogt, jslaby, suse, tiwai
Version:	Current	Flags:	tiwai: needinfo? (suse)
Target Milestone:	---
Hardware:	x86-64
OS:	openSUSE Tumbleweed
Whiteboard:
Found By:	---	Services Priority:
Business Priority:		Blocker:	---
Marketing QA Status:	---	IT Deployment:	---

Description Uberrice 2024-06-03 19:47:50 UTC

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36
Build Identifier:

So, this bug started happening very recently, all was fine before.

I use a T14G2 AMD as my 'secondary device' alongside my desktop, and have it set up to have the Ultra dock connect to alternate Inputs of my screen. If I want to switch from desktop to laptop, I switch the monitor's input, and switch my USB KVM over to the laptop for mouse/keyboard. This includes one over HDMI, and one over DisplayPort.

What started happening, is that sometimes, when switching over, specifically when changing the monitor input, the whole system freezes up and gets unresponsive; this is only fixed with a hard power down (5s press). It doesn't always happen immediately, but most often does if the input was switched to another device for a longer time (>10 minutes). It doesn't matter if the laptop screen is active or not - the moment I switch the monitor input, the system locks up - I verified this by leaving the laptop's screen active. Mouse moved, switch monitor input to output the KDE system, system frozen.

Checking journalctl I get no even remotely relevant messages - the system itself still appears to be running up to the point of the hang - no journalctl entries afterwards. Can't switch to terminal only mode (ctrl+alt+F keys) either, so it's not just KDE that's hanging.

Reproducible: Always

Steps to Reproduce:
1. Start laptop system with external monitors attached
2. Switch away monitor inputs for ~10-15 minutes
3. Switch back to inputs to laptop

Unclear if related to docking station (Thinkpad Ultra https://support.lenovo.com/us/en/solutions/pd500173-thinkpad-ultra-docking-station-overview-and-service-parts )
Actual Results:
System becomes unresponsive

Expected Results:
System continues working normally

Comment 1 Uberrice 2024-06-03 19:53:19 UTC

I forgot to mention:

Disconnecting the dock and/or 'waiting it out' also changes nothing - the system is totally unresponsive until a hard reset.

Comment 2 Fabian Vogt 2024-06-04 07:30:49 UTC

> Can't switch to terminal only mode (ctrl+alt+F keys) either, so it's not just KDE that's hanging.

-> kernel

Comment 3 Takashi Iwai 2024-06-17 09:08:13 UTC

Is it a regression in the recent kernel updates?

Also, for the dock, make sure that you update to the latest BIOS version.

Comment 4 Uberrice 2024-06-17 20:48:02 UTC

I am further exploring what exactly is causing the freeze.

I did update the BIOS - I was on like a half a year old version, though that shouldn't be too big of a problem as the dock is older than that and it has worked without a problem before. That wasn't it - it still happens.

I did notice that it doesn't ALWAYS happen, and takes quite a while to manifest. Tried to rule out it didn't happen because of certain applications, which it didn't - happened regardless of what was running.


Changed to 6.6.32-2-longterm kernel from https://download.opensuse.org/repositories/Kernel:/ - that one doesn't seem to have the issue.

Comment 5 Takashi Iwai 2024-06-18 11:11:48 UTC

OK, then could you check 6.7 and 6.8 kernels show the problem?  We want to narrow down the regression change.
You can find in my OBS repos:
  http://download.opensuse.org/repositories/Kernel:/6.7/standard/
  http://download.opensuse.org/repositories/Kernel:/6.8/standard/
Note that those are unofficial builds, hence you'd need to disable Secure Boot.

I guess the official 6.8 kernel is still found in OBS TW history repo, too:
  http://download.opensuse.org/history/

Comment 6 Uberrice 2024-06-18 12:37:57 UTC

Just ran a single test - but the issue didn't appear on 6.8.9-1-default (from 20240520 in history)

It definitely appeared after the upgrade to 6.9 - somewhere around the beginning of June. Obviously didn't immediately notice it however.

I'll stay on 6.8.9-1 for a day or two and update you if the problem surfaces here as well, but I'm fairly sure at this point it'll be contained to 6.9.

If you want to test a fix or get some diagnostics, I'm happy to help.

Comment 7 Takashi Iwai 2024-06-24 15:07:18 UTC

OK, then try the latest 6.9.6 kernel in OBS Kernel:stable repo, and verify that the problem persists.  If yes, try the 6.10-rc kernel in OBS Kernel:HEAD repo.

If the problem appears in both, it's a remaining regression in the upstream, and it should be reported / fixed there.  See
  https://www.kernel.org/doc/html/latest/admin-guide/reporting-regressions.html

Comment 8 Uberrice 2024-07-01 12:22:38 UTC

Seems to be fixed in 6.9.6-1-default. Should the problem reappear at some point, I will reopen.