https://bugs.kde.org/show_bug.cgi?id=523287
Bug ID: 523287
Summary: kwin_wayland crashes (SEGV) in
DrmOutput::testPresentation on NVIDIA RTX 4070
(atomic commit null-deref) — at session start and on
fullscreen
Classification: Plasma
Product: kwin
Version First 6.6.5
Reported In:
Platform: Kubuntu
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: platform-drm
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 194459
--> https://bugs.kde.org/attachment.cgi?id=194459&action=edit
bug-kwin-journal
kwin_wayland crashes with SIGSEGV inside
KWin::DrmOutput::testPresentation
(atomic test-commit null dereference) on an NVIDIA GeForce RTX 4070.
Triggers: (1) at Plasma Wayland session startup (initial composite), and
(2) when a fullscreen OpenGL/Vulkan app (Godot 4.7.1) goes fullscreen —
the client then loses its display ("X connection to :0 broken").
ENVIRONMENT
- OS: Ubuntu 26.04 LTS (Kubuntu), kernel 7.0.0-28-generic
- KWin: 6.6.5 (package 4:6.6.5-0ubuntu0.1)
- Plasma: 6.6.5 KDE Frameworks: 6.24.0 Qt: 6.10.2
- kwin_wayland build-id: c59b9504d168ac869b5482cabd80553bbe764cc6
- GPU: NVIDIA GeForce RTX 4070 (AD104), single monitor DP-1 @ 1920x1080
- Driver: 610.43.02, OPEN kernel modules (license: Dual MIT/GPL)
- libdrm 2.4.131, mesa 26.0.3
- Kernel cmdline: nvidia-drm.modeset=1
- SDDM greeter runs Wayland (kwin_wayland --drm)
REPRODUCIBLE WITH BOTH proprietary AND open NVIDIA 610.43.02 modules
(identical backtrace) -> not a specific module regression.
STEPS TO REPRODUCE
1. Boot into Plasma (Wayland) on RTX 4070.
2. kwin_wayland crashes during startup (before/at first composite).
OR
2'. Log in, launch Godot 4.7.1 (Vulkan), press fullscreen.
3. kwin_wayland crashes; XWayland client loses display.
ACTUAL RESULTS
kwin_wayland SIGSEGV; session restarts or drops to display loss.
EXPECTED RESULTS
Stable Wayland session; fullscreen games should not crash kwin.
BACKTRACE (symbolicated)
Thread 1 "RenderLoop::frameRequested":
#12
KWin::DrmOutput::testPresentation(std::shared_ptr<KWin::OutputFrame>
const&) (libkwin.so.6 + 0x53a75f)
#13 KWin::Compositor::composite(KWin::RenderLoop*)
(libkwin.so.6 + 0x20a608)
#15 KWin::RenderLoop::frameRequested(KWin::RenderLoop*)
(libkwin.so.6 + 0x239e6a)
SEGV occurs inside the atomic commit path:
#6..#11 libkwin.so.6 (+0x50ff23 / 0x51586d / 0x543d41 / 0x545db4 /
0x546099 / 0x5466c9)
(DrmPipeline::present / atomic test commit)
WORKAROUND THAT WORKS
Logging into the Plasma (X11) session is stable (kwin_x11 unaffected).
NOTES
- KWIN_DRM_NO_AMS=1 -> blackscreen after login (legacy mode broken on this
GPU).
- KWIN_DRM_USE_MODIFIERS=0 -> blackscreen after login.
- Attachments: journalctl -b (kwin/drm errors), nvidia-smi -q, drkonqi
metadata.
--
You are receiving this mail because:
You are watching all bug changes.
