Bug 453824

Summary:	System hangs occasionally when making windows fullscreen
Product:	[Plasma] kwin	Reporter:	Maugre <maugrerain>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	maugrerain, nate, xaver.hugl
Priority:	NOR	Keywords:	regression
Version:	5.24.5
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	dmesg log (from before issue has occurred)

Description Maugre 2022-05-15 12:43:30 UTC

SUMMARY
My system hangs when making some windows fullscreen. It's happened most frequently in mpv when using VA-API but also occurred in Firefox (fullscreen mode, mouse at top to expose/hide toolbar), Gwenview, wine, and others. This has happened on all versions of 5.24 (including beta).

***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***
The system hangs requiring me to hit the reset button. There's nothing in journal or any other kind of log that I can see. I'll need help figuring out how to get a useful debug log.

STEPS TO REPRODUCE
As stated, this happens in several applications but most frequently in mpv with VA-API enabled (rarely without hwdec) so I'll use that:
1. Open a suitable video file (e.g. h264 encoded) in mpv with hwdec enabled (or press Ctrl+H to enable). Check by pressing I key and look for "(hwdec: vaapi)" in the "Video:" line.
2. Maximise window (may be optional). Press f key to enable fullscreen.

OBSERVED RESULT
*Sometimes* my system hangs, becoming totally unresponsive to any input and SSH sessions are terminated/timeout. No option but to hit a physical reset button. No keyboard shortcuts, e.g. 'REISUB' or Ctrl+Alt+Delete, have any effect.

EXPECTED RESULT
Video (or other application) should continue to play in fullscreen mode.

SOFTWARE/OS VERSIONS
Linux: Manjaro Linux 5.15-5.17 standard kernels, plus 5.17.7-xanmod1-2-x64v2
KDE Plasma Version: 5.23.90-5.24.5
KDE Frameworks Version: 5.91-5.93
Qt Version: 5.15.3

ADDITIONAL INFORMATION
The only thing "special" about my system is it's all AMD (3700X + 6800 XT) and using a xanmod 'edge' kernel, but this also happened with standard Manjaro kernels from 5.15-5.17. However, this didn't occur with Plasma 5.23 (excluding 5.24 beta) so I'm not convinced my particular config is the reason. This also never happened on my Intel laptop. Of course, it could be that something in Kwin is exposing a bug elsewhere; this is merely a starting point as it's the only common factor I can think of.

Comment 1 Maugre 2022-05-15 12:59:29 UTC

Created attachment 148846 [details]
dmesg log (from before issue has occurred)

I can't get a log after this occurs but here's a dmesg log from before it, in case anything stands out.

Comment 2 Nate Graham 2022-05-15 17:06:39 UTC

Cannot reproduce with current git master everything, testing fullscreen MPV and vaapi decoding enabled.

My system is all Intel, though.

Comment 3 Zamundaaa 2022-05-16 14:24:03 UTC

Can't reproduce either with a rx 6800 XT and up to date Manjaro (kernel 5.16.20-2). Both git master and stable kde session handle fullscreen mpv with hardware decoding fine.
A full system hang, including ssh, can pretty much only be caused by some kernel bug. Please report it to https://gitlab.freedesktop.org/drm/amd/-/issues

Comment 4 Maugre 2022-05-16 23:21:35 UTC

(In reply to Zamundaaa from comment #3)
> Can't reproduce either with a rx 6800 XT and up to date Manjaro (kernel
> 5.16.20-2). Both git master and stable kde session handle fullscreen mpv
> with hardware decoding fine.
> A full system hang, including ssh, can pretty much only be caused by some
> kernel bug. Please report it to
> https://gitlab.freedesktop.org/drm/amd/-/issues

Thanks for trying. Looks similar to https://gitlab.freedesktop.org/drm/amd/-/issues/1973

Maybe it's specific to early RDNA2 cards as they report no problem with another card. I'll continue discussion there.