https://bugs.kde.org/show_bug.cgi?id=503070
Bug ID: 503070
Summary: KWin_Wayland crash renders session unrecoverable: TTY
fails, GPU remains locked, and existing windows die
Classification: Plasma
Product: kwin
Version: 6.3.4
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: critical
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: swaraj1010746...@gmail.com
Target Milestone: ---
SUMMARY
When running KDE Plasma 6 on Wayland, the entire user session silently
terminates if the kwin_wayland compositor crashes — whether at the desktop,
lock screen, or SDDM login screen (when running SDDM in Wayland mode). This is
not an isolated crash of a window manager but a total session-level failure,
resulting in:
GPU DRM master remaining locked.
TTY switching failing (e.g., Ctrl+Alt+F3 → black screen).
Remote access (SSH, VNC) failing, as systemd --user may be terminated or
orphaned.
Input devices no longer working across any VTs.
System requiring hard reboot or virtual console kill signals to recover.
This appears to be due to the compositor owning the GPU DRM device exclusively
under Wayland, and failing to cleanly release it when the session collapses.
The session is not marked as “logged out” cleanly by logind, which results in
loss of fallback mechanisms. It occurs without user interaction — even idle
lock screen or SDDM inactivity can trigger the crash silently, killing the
system’s ability to recover gracefully.
STEPS TO REPRODUCE
1. Configure SDDM to run in Wayland mode (DisplayServer=wayland) and use Plasma
6 with a Wayland session.
2. Boot system and reach the SDDM login screen (Wayland).
3. Allow the system to idle or interact normally with the greeter.
3.1. Alternatively: Log in and allow the desktop to idle.
Note - In some cases: a passive crash occurs (with no interaction).
4. Return to the system and observe black screen or dead session.
OBSERVED RESULT
The user session terminates entirely:
Input devices stop responding.
TTYs (Ctrl+Alt+F3) do not function; display remains black.
All processes under systemd --user are killed or frozen.
GPU remains locked via DRM, no fallback graphical session possible.
At the lock screen or SDDM: screen goes black, input is dead, and system
appears hung.
HDR (if enabled) may attempt to reinitialize but hangs or flashes briefly
before failure.
SSH into the system may or may not work — depending on how logind interpreted
the crash.
Requires hard reboot to recover.
EXPECTED RESULT
The compositor should not crash at all during normal or idle usage — whether on
the desktop, lock screen, or at the SDDM greeter. This includes idle states,
screen lock, HDR negotiation, and theme rendering. KDE Plasma should be
resilient against passive crashes or compositor instability under any expected
system state.
However, if a compositor crash does occur (due to unforeseen edge cases or
driver issues), then:
The session manager should remain alive and functional.
The DRM lock should be released to allow fallback to TTY or greeter
recovery.
Remote access (SSH/VNC) and user background services should continue
running.
SDDM should recover or restart cleanly without locking the display device.
Input devices (keyboard, mouse, tablet) should remain responsive.
HDR and display modes should reinitialize gracefully upon recovery.
Existing applications should at least receive a shutdown event, or
optionally support reattachment via protocol extension.
Linux/KDE Plasma: Arch Linux (rolling), fully up to date
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.12.0
Qt Version: 6.9.0
Kernel: 6.14.2-arch1-1
Mesa: Latest Arch build
Processor: AMD Ryzen 7 9800X3D 8-Core Processor
GPU: AMD RX 9070 XT
Driver: amdgpu
Display Server: Wayland
Shell: bash 5.2.37
DE Host: B650 GAMING X AX V2
Resolution: 3440x1440
Compositor: kwin_wayland
ADDITIONAL INFORMATION
Workaround Implemented:
Created user-level systemd override for plasma-kwin_wayland.service:
[Service]
Restart=always
RestartSec=2
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