Created attachment 169605 [details] kwin_wayland crash trace output from drkonqi SUMMARY I booted the Fedora Rawhide/41 KDE Plasma live image Fedora-KDE-Live-x86_64-Rawhide-20240518.n.0.iso in a QEMU/KVM VM using GNOME Boxes with 3D acceleration disabled using the llvmpipe driver from mesa 24.1.0-rc4. Plasma 6.0.4 on Wayland started. I started Konsole. I tried to run a nested kwin_wayland session using the instructions at https://community.kde.org/KWin/Wayland export $(dbus-launch) kwin_wayland --xwayland The nested kwin_wayland window didn't appear. A Wayland icon appeared in the task manager briefly then disappeared. The following output was in Konsole which showed a Permission denied error and a segmentation fault of kwin_wayland. export $(dbus-launch) kwin_wayland --xwayland No backend specified, automatically choosing Wayland because WAYLAND_DISPLAY is set unable to lock lockfile /run/user/1000/wayland-0.lock, maybe another compositor is running Accepting client connections on sockets: QList("wayland-1") OpenGL vendor string: Mesa OpenGL renderer string: llvmpipe (LLVM 18.1.4, 256 bits) OpenGL version string: 4.5 (Core Profile) Mesa 24.1.0-rc4 OpenGL shading language version string: 4.50 Driver: LLVMpipe GPU class: Unknown OpenGL version: 4.5 GLSL version: 4.50 Mesa version: 24.1 Requires strict binding: no Virtual Machine: no Timer query support: yes KMS: DRM_IOCTL_MODE_CREATE_DUMB failed: Permission denied KMS: DRM_IOCTL_MODE_CREATE_DUMB failed: Permission denied KMS: DRM_IOCTL_MODE_CREATE_DUMB failed: Permission denied KMS: DRM_IOCTL_MODE_CREATE_DUMB failed: Permission denied qt.qpa.wayland: Creating a fake screen in order for Qt not to crash Segmentation fault (core dumped) liveuser@localhost-live:~$ The Wayland connection broke. Did the Wayland compositor die? The nested kwin_wayland crashed in KWin::EglSwapchainSlot::buffer. The crash might've been due to a null pointer dereference since this=0x0 in KWin::EglSwapchainSlot::buffer. Core was generated by `kwin_wayland --xwayland'. Program terminated with signal SIGSEGV, Segmentation fault. #0 KWin::EglSwapchainSlot::buffer (this=0x0) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/opengl/eglswapchain.cpp:39 39 return m_buffer; [Current thread is 1 (Thread 0x7f1ca443ab00 (LWP 2894))] Thread 1 (Thread 0x7f1ca443ab00 (LWP 2894)): #0 KWin::EglSwapchainSlot::buffer (this=0x0) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/opengl/eglswapchain.cpp:39 #1 0x00007f1ca526dd18 in KWin::Wayland::WaylandEglPrimaryLayer::present (this=0x556c1bcd3a50) at /usr/include/c++/14/bits/shared_ptr_base.h:1666 #2 KWin::Wayland::WaylandEglBackend::present (this=<optimized out>, output=<optimized out>, frame=std::shared_ptr<KWin::OutputFrame> (use count 1, weak count 0) = {...}) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/backends/wayland/wayland_egl_backend.cpp:330 #3 0x00007f1ca4fa8496 in KWin::Compositor::composite (this=0x556c18467990, renderLoop=<optimized out>) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/compositor.cpp:201 #4 0x00007f1ca23fa3c4 in QtPrivate::QSlotObjectBase::call (this=0x556c1bd50870, r=<optimized out>, a=0x7ffcfc84dbf0) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobjectdefs_impl.h:469 #5 doActivate<false> (sender=0x556c183c01f0, signal_index=5, argv=0x7ffcfc84dbf0) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobject.cpp:4078 #6 0x00007f1ca23f0977 in QMetaObject::activate (sender=<optimized out>, m=<optimized out>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7ffcfc84dbf0) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobject.cpp:4138 #7 0x00007f1ca4fc1c34 in KWin::RenderLoop::frameRequested (this=<optimized out>, _t1=<optimized out>) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/redhat-linux-build/src/kwin_autogen/include/moc_renderloop.cpp:208 #8 0x00007f1ca4fc83ef in KWin::RenderLoopPrivate::dispatch (this=0x556c183d37a0) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/core/renderloop.cpp:128 #9 0x00007f1ca23fa3c4 in QtPrivate::QSlotObjectBase::call (this=0x556c183bdc50, r=<optimized out>, a=0x7ffcfc84dd30) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobjectdefs_impl.h:469 #10 doActivate<false> (sender=0x556c183d37c0, signal_index=3, argv=0x7ffcfc84dd30) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobject.cpp:4078 #11 0x00007f1ca23f0977 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x7f1ca28830a0, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffcfc84dd30) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobject.cpp:4138 #12 0x00007f1ca240941d in QTimer::timeout (this=<optimized out>, _t1=...) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/redhat-linux-build/src/corelib/Core_autogen/include/moc_qtimer.cpp:224 #13 0x00007f1ca23ebc9f in QObject::event (this=0x556c183d37c0, e=0x7ffcfc84dee0) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qobject.cpp:1476 #14 0x00007f1ca378b368 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt6Widgets.so.6 #15 0x00007f1ca2395a98 in QCoreApplication::notifyInternal2 (receiver=0x556c183d37c0, event=0x7ffcfc84dee0) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qcoreapplication.cpp:1134 #16 0x00007f1ca2395cfd in QCoreApplication::sendEvent (receiver=<optimized out>, event=<optimized out>) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qcoreapplication.cpp:1575 #17 0x00007f1ca254d6d7 in QTimerInfoList::activateTimers (this=this@entry=0x556c182f4d08) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qtimerinfo_unix.cpp:436 #18 0x00007f1ca254f9f0 in QEventDispatcherUNIXPrivate::activateTimers (this=this@entry=0x556c182f4c30) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:196 #19 0x00007f1ca2551bfb in QEventDispatcherUNIX::processEvents (this=<optimized out>, flags=...) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/kernel/qeventdispatcher_unix.cpp:472 #20 0x00007f1ca3155052 in QUnixEventDispatcherQPA::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt6Gui.so.6 #21 0x00007f1ca23a2693 in QEventLoop::exec (this=this@entry=0x7ffcfc84e0b0, flags=..., flags@entry=...) at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/global/qflags.h:34 #22 0x00007f1ca239e61c in QCoreApplication::exec () at /usr/src/debug/qt6-qtbase-6.7.0-5.fc41.x86_64/src/corelib/global/qflags.h:74 #23 0x0000556bf39f0d0f in main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kwin-6.0.4.1-3.fc41.x86_64/src/main_wayland.cpp:609 This problem happened 2/2 times I tried to run a nested kwin_wayland session in a VM using the llvmpipe driver. I'm attaching the full trace from drkonqi which said the trace didn't have enough useful information. STEPS TO REPRODUCE 1. Boot a Fedora 40 KDE Plasma installation updated to 2024-5-19 with updates-testing enabled 2. Log in to Plasma 6.0.4 on Wayland 3. Start Konsole 4. Install GNOME Boxes if it isn't already with sudo dnf install gnome-boxes 5. Download Fedora-KDE-Live-x86_64-Rawhide-20240518.n.0.iso from https://koji.fedoraproject.org/koji/buildinfo?buildID=2453143 6. Start GNOME Boxes 7. Boot Fedora-KDE-Live-x86_64-Rawhide-20240518.n.0.iso in a GNOME Boxes QEMU/KVM VM with 3 GiB RAM, UEFI enabled, and 3D acceleration disabled 8. Start Konsole 9. In Konsole, run export $(dbus-launch) kwin_wayland --xwayland OBSERVED RESULT Nested kwin_wayland crashed in KWin::EglSwapchainSlot::buffer in VMs using the llvmpipe driver EXPECTED RESULT Nested kwin_wayland shouldn't have crashed SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora Rawhide (available in About System) KDE Plasma Version: 6.0.4 KDE Frameworks Version: 6.2.0 Qt Version: 6.7.0 ADDITIONAL INFORMATION I reported a nested kwin_wayland crash with a different trace at https://bugs.kde.org/show_bug.cgi?id=478864 which had a patch marked as fixing the problem.
you're running kwin_wayland without all the fixes. try 6.0.5
(In reply to Vlad Zahorodnii from comment #1) > you're running kwin_wayland without all the fixes. try 6.0.5 I tried Plasma 6.0.5 and 6.0.90 in VMs using the llvmpipe driver, and nested kwin_wayland didn't crash but its window didn't appear. Just a task manager Wayland icon labelled KDE Wayland compositor WL-0 was shown which didn't show the window when I tried to click on it or maximize it. Thanks.
Nested kwin_wayland 6.0.5 crashed with a different trace that of 6.0.4 from each other in VMs using llvmpipe https://bugs.kde.org/show_bug.cgi?id=487857 Nested kwin_wayland 6.0.90.1 window didn't appear, but it didn't crash as I described https://bugs.kde.org/show_bug.cgi?id=487860