Bug 511022 - When running two concurrent Wayland seats (seat0 → amdgpu, seat1 → nvidia-drm), both Plasma sessions enumerate all DRM devices. As a result, the NVIDIA kernel driver logs WARNs about "revoke modeset permission", and both compositors occasionally crash.
Summary: When running two concurrent Wayland seats (seat0 → amdgpu, seat1 → nvidia-drm...
Status: RESOLVED DOWNSTREAM
Alias: None
Product: kwin
Classification: Plasma
Component: wayland-generic (other bugs)
Version First Reported In: 6.3.6
Platform: Other Linux
: NOR crash
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-10-24 13:52 UTC by Sam James
Modified: 2025-10-24 14:33 UTC (History)
0 users

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Description Sam James 2025-10-24 13:52:03 UTC 
System
-------
• Debian 13, Plasma 6.3.6
• systemd 257
• Kernel 6.12.48
• NVIDIA 550.163.01, amdgpu (Ryzen 9 7950X iGPU)
• seat0: amdgpu + 1 monitor
• seat1: nvidia + 3 monitors

Symptoms
--------
- `journalctl` shows NVIDIA kernel warning:
  `nv_drm_revoke_modeset_permission+0x327/0x340 [nvidia_drm]`
- `kwin_x11` / `plasmashell` / `drkonqi` sometimes crash
- Chrome under Wayland SIGILLs repeatedly (GPU process)
- Disabling one GPU or running single-seat Wayland removes the issue

Expected
--------
Each KWin instance should restrict itself to the DRM device(s) belonging to its own seat.

Diagnostics
-----------
`loginctl seat-status seat0/seat1` correctly lists devices, yet both compositors still appear to open `/dev/dri/card0` and `/dev/dri/card1`.
Logs and kernel WARN attached.

Related upstream discussion
----------------------------
https://forums.developer.nvidia.com/t/multi-seat-wayland-amd-nvidia-causes-nv-drm-revoke-modeset-permission-warn-and-repeated-user-space-crashes/348845
Comment 1 Bug Janitor Service 2025-10-24 14:33:43 UTC 
Thank you for the bug report!

However Plasma 6.3.6 no longer receives updates or maintenance from KDE; active versions are 6.4 or newer. Please upgrade to an active version as soon as your distribution makes it available to you. Plasma is a fast-moving project, and bugs in one version are often fixed in the next one.

If you need help with Plasma 6.3.6, please contact your distribution, who bears the responsibility of providing help for older releases that are no longer receiving updates from KDE.

If you can reproduce the issue after upgrading to an active version, feel free to re-open this bug report.