Bug 497222

Summary:	ksplashqml and plasmashell crashed when Plasma started in VMs with 3D acceleration enabled
Product:	[Plasma] plasmashell	Reporter:	Matt Fagnani <matt.fagnani>
Component:	generic-crash	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	crash	CC:	kdedev
Priority:	NOR	Keywords:	qt6
Version First Reported In:	6.2.4
Target Milestone:	1.0
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	plasmashell trace screenshot

Description Matt Fagnani 2024-12-09 04:59:13 UTC

Created attachment 176453 [details]
plasmashell trace screenshot

SUMMARY

I booted the Fedora Rawhide KDE live image Fedora-KDE-Desktop-Live-Rawhide-20241208.n.0.x86_64.iso in QEMU/KVM VMs with 3D acceleration enabled using the virgl mesa 24.3.1 driver in GNOME Boxes in a Fedora 41 KDE installation. When Plasma 6.2.4 on Wayland was starting, the startup sound played. There was a second mouse cursor in the middle of the VM screen for a couple seconds which disappeared. The VM had a black screen indefinitely after that. I switched to VT2 in the VM. ksplashqml and plasmashell crashed when Plasma started. plasmashell crashed 3 times. plasma-welcome also crashed. coredumpctl gdb showed those processes crashed in dri2_query_image_common in mesa with the same kinds of traces. The plasmashell trace had a null image pointer in dri2_query_image_common (and lower frames). The crashing line in dri2_query_image_common was *value = image->texture->width0; The crash might be due to a null pointer dereference there. I took a screenshot of the plasmashell trace since I'm unsure how to transfer text files out of the VM without Plasma starting. I'm writing out most of the plasmashell trace from the attached screenshot as follows.

#0 __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=11, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1 in __pthread_kill_internal (threadid=<optimized out>, signo=11) at pthread_kill.c:89
#2 in __GI_raise (sig=11) at ../sysdeps/raise/posix.c:26
#3 in KCrash::defaultCrashHandler (sig=11) at /usr/src/debug/kf6-kcrash-6.8.0-1.fc42.x86_64/src/kcrash.cpp:596
#4 <signal handler called>
#5 in dri2_query_image_common (image=0x0, attrib=8196, value=...) at ../src/gallium/frontends/dri/dri2.c:1211
#6 in dri2_query_image (image=0x0, attrib=8196, value=...) at ../src/gallium/frontends/dri/dri2.c:1410
#7 in create_wl_buffer (dri2_dpy=..., dri2_surf=..., image=0x0) at ../src/egl/drivers/dri2/wayland_platform.c:1471
#8 in dri2_wl_swap_buffers_with_damage (disp=..., draw=..., rects=0x0, nrects=0)  at ../src/egl/drivers/dri2/wayland_platform.c:1674
#9 in dri2_swap_buffers (disp=..., surf=...)  at ../src/egl/drivers/dri2/egl_dri2.c:1659
#10 in eglSwapBuffers (dpy=..., surface=...)  at ../src/egl/main/eglapi.c:1458
#11 in QtWaylandClient::QtWaylandGLContext::swapBuffers (this=..., surface=...) at /usr/src/debug/qt6-qtwayland-6.8.1-2.fc42.x86_64/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp:404
#12 in QRhiGles2::endFrame (this=..., swapChain=..., flags=...) at /usr/src/debug/qt6-qtbase-6.8.1-4.fc42.x86_64/src/gui/rhi/qrhigles2.cpp:2166
#13 in QRhi::endFrame (this=..., swapChain=..., flags=...) at /usr/src/debug/qt6-qtbase-6.8.1-4.fc42.x86_64/src/gui/rhi/qrhi.cpp:10878
#14 in QSGRenderThread::syncAndRender (this=...) at /usr/include/qt6/QtCore/qtflags.h:73
#15 in QSGRenderThread::run (this=...) at /usr/src/debug/qt6-qtdeclarative-6.8.1-5.fc42.x86_64/src/quick/scenegraph/qsgthreadedrenderloop.cpp:975
...

This problem happened 3/3 boots of that image with 3D acceleration enabled. When I ran sudo systemctl restart sddm from VT2, the same crashes happened. The problem didn't happen with 3D acceleration disabled using the llvmpipe mesa driver. So the problem might involve the virgl driver in mesa 24.3.1. The problem might also involve Qt 6.8.1 which was just updated in Rawhide. This issue didn't happen with a Fedora Rawhide image from November 29 with Plasma 6.2.4, KF 6.8.0, Qt 6.8.0, and mesa 24.3.0.

STEPS TO REPRODUCE
1. Download the Fedora Rawhide KDE live image Fedora-KDE-Desktop-Live-Rawhide-20241208.n.0.x86_64.iso from https://koji.fedoraproject.org/koji/buildinfo?buildID=2598435 in a Fedora 41 KDE installation
2. Boot Fedora-KDE-Desktop-Live-Rawhide-20241208.n.0.x86_64.iso in a QEMU/KVM VM with 3D acceleration enabled, 4 GiB RAM, UEFI enabled in GNOME Boxes
3. 

OBSERVED RESULT
ksplashqml and plasmashell crashed when Plasma started in VMs with 3D acceleration enabled

EXPECTED RESULT
Plasma should've started normally

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Rawhide
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION

Comment 1 Matt Fagnani 2024-12-09 06:56:20 UTC

I downgraded to mesa 24.3.0 in a VT in the VM with the problem. When I ran sudo systemctl restart sddm, Plasma started normally. The problem seems to be with mesa 24.3.1. A mesa 24.3.1 regression was reported including crashes in alacritty in dri2_query_image at https://gitlab.freedesktop.org/mesa/mesa/-/issues/12253 Other comments on that report mentioned crashes in Plasma with certain AMD GPUs. My system has an AMD Radeon R5 integrated GPU.

Comment 2 TraceyC 2024-12-19 23:05:34 UTC

Thanks for the bug report, and the link to the issue in the mesa tracker.

The merge request related to the mesa bug report shows that it was merged. It looks like the fix will be in mesa 24.3.2.