Bug 486628

Summary:	Sometimes, after screen lock timeout, screen will stay black until kwin_wayland is killed
Product:	[Plasma] kwin	Reporter:	Eduardo Sánchez Muñoz <eduardosanchezmunoz>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	grave	CC:	nate
Priority:	NOR
Version First Reported In:	6.0.4
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Eduardo Sánchez Muñoz 2024-05-05 15:27:55 UTC

SUMMARY

Sometimes, when the screen locks due to timeout, the screen will stay black with a movable cursor. The only way out is switching to a TTY and killing kwin_wayland, which will cause most applications to crash.

STEPS TO REPRODUCE
1. Wait for the screen to lock.
2. Move the mouse

OBSERVED RESULT

Sometimes, the screen will stay black and it will not be possible to unlock the session normally.

EXPECTED RESULT

A password prompt should appear.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Fedora Linux 40
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0

ADDITIONAL INFORMATION

Running "loginctl unlock-sessions" or killing plasmashell does not help to recover, only killing kwin_wayland. One of the times it happened, after killing kwin_wayland, I logged out and I was not able to log back in until I rebooted.

Comment 1 Nate Graham 2024-05-05 20:38:59 UTC

Sounds bad.

Does this happen if you lock and then immediately try to prevent locking by moving the cursor right after it locks? Or does it happen when the auto-lock happens and then you don't supply any kind of interaction for a while?

Comment 2 Eduardo Sánchez Muñoz 2024-05-05 21:34:48 UTC

It happens when I move the mouse immediately after it locks to prevent locking. In "EXPECTED RESULT", I should have said that I expected the session to unlock after moving the mouse, not a password prompt.

My "Lock screen automatically" and "Dim automatically" settings are set to the same value (usually 5 minutes, now 1 minute for testing). "Allow unlocking without password" is set to 5 seconds.

Comment 3 Eduardo Sánchez Muñoz 2024-05-06 16:29:05 UTC

Another detail. I can reproduce this with an AMD GPU, but not with an Intel GPU.

OpenGL vendor string: AMD
OpenGL renderer string: AMD Radeon RX 7800 XT (radeonsi, navi32, LLVM 18.1.1, DRM 3.57, 6.8.8-300.fc40.x86_64)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 24.0.6
OpenGL core profile shading language version string: 4.60

OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) UHD Graphics 630 (CFL GT2)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 24.0.6
OpenGL core profile shading language version string: 4.60

Comment 4 Nate Graham 2024-05-06 21:10:05 UTC

I can reproduce this 100%, and I have an Intel iGPU.

Steps:
1. Let the screen locj naturally (does not happen if yo lock it with Meta+L
2. Move the mouse within the gracelock period (5 seconds by default)

Boom, black screen with movable cursor. Looks like it's Bug 476567, which has returned. Marking as a duplicate of it.

*** This bug has been marked as a duplicate of bug 476567 ***