Multi-seat Wayland (AMD + NVIDIA) causes nv_drm_revoke_modeset_permission WARN and repeated user-space crashes

Graphics / Linux Linux
1

Environment

• Hardware:

  • CPU: AMD Ryzen 9 7950X (AM5)
  • GPUs:
    • Integrated AMD Radeon 780M (amdgpu)
    • NVIDIA GeForce RTX 3050 (nvidia-drm)
  • Motherboard: Gigabyte X670 AORUS ELITE AX (UEFI F4, 08/24/2022)
  • Displays: 1 monitor on AMD seat 0, 3 monitors on NVIDIA seat 1 (true multiseat)

• Software:

  • Debian 13 (testing/trixie)
  • Kernel 6.12.48+deb13-amd64
  • NVIDIA driver 550.163.01 (DKMS)
  • Plasma 6.3.6 / Wayland
  • systemd 257

Problem

Running two concurrent Wayland seats (seat0 → amdgpu, seat1 → nvidia-drm) triggers kernel warnings and unstable behaviour:

WARNING: CPU: 22 PID: 3628 at nv_drm_revoke_modeset_permission+0x327/0x340 [nvidia_drm]
Tainted: P W O E 6.12.48+deb13-amd64
Call Trace:
drm_file_free+0x218/0x270 [drm]
drm_release+0x5e/0xd0 [drm]
__fput+0xde/0x2a0
…
User-space symptoms:

  • Frequent SIGILL / SIGSEGV in Chrome (Wayland, Ozone-GBM)
  • Periodic crashes of KWin/Plasma (kwin_x11, plasmashell, drkonqi)
  • Journal flooded by drkonqi-coredump-launcher.socket retries after repeated renderer crashes

Steps to Reproduce

  1. Configure true multiseat:
    • Seat 0 → /dev/dri/card0 (amdgpu)
    • Seat 1 → /dev/dri/card1 (nvidia-drm)
  2. Log into two concurrent Wayland sessions.
  3. Launch fwupd or open Chrome on either seat.

Observed Result

• Kernel emits WARN above from nv_drm_revoke_modeset_permission.
• Both seats experience random application crashes and coredumps.
• If the NVIDIA module is blacklisted or Wayland uses only one GPU, the issue disappears.

Expected Result

• NVIDIA DRM KMS should coexist safely with another DRM driver (amdgpu) on a separate seat.
• fwupd, Chrome, and compositors should not trigger WARNs or instability.

Notes

  • This only occurs when both GPUs are active under different seats.
  • On X11 seats (one Xorg per GPU) the system is stable.
  • Appears to involve modeset-permission handoff across seats.

Logs & Diagnostics

• Full dmesg + journal excerpts attached.
• nvidia-bug-report.sh archive available on request.

Please advise whether this configuration is supported and if multi-seat isolation between amdgpu and nvidia-drm is expected to work under Wayland.

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