Application: kwin_x11 (5.11.95)

Qt Version: 5.10.0
Frameworks Version: 5.42.0
Operating System: Linux 4.15.0-loonix x86_64
Distribution (Platform): Archlinux Packages

-- Information about the crash:
Pressing and holding alt-tab to switch between running programs crashes kwin_x11 when "Thumbnails" is selected as Task switcher. To reproduce the bug, keep pressed alt+tab to rapidly switch between running programs.

The crash can be reproduced every time.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fc923a2f840 (LWP 2066))]

Thread 13 (Thread 0x7fc901b7d700 (LWP 30419)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 12 (Thread 0x7fc8c77fe700 (LWP 2144)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc91f63cf77 in  () at /usr/lib/libQt5Script.so.5
#2  0x00007fc91f63cfb9 in  () at /usr/lib/libQt5Script.so.5
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 11 (Thread 0x7fc8e4b08700 (LWP 2141)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 10 (Thread 0x7fc8e5309700 (LWP 2140)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 9 (Thread 0x7fc8e5b0a700 (LWP 2139)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 8 (Thread 0x7fc8e630b700 (LWP 2138)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 7 (Thread 0x7fc8e6b0c700 (LWP 2137)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 6 (Thread 0x7fc8e730d700 (LWP 2136)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 5 (Thread 0x7fc8e7b0e700 (LWP 2135)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 4 (Thread 0x7fc8e830f700 (LWP 2134)):
#0  0x00007fc91c35d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fc8f12d0fec in  () at /usr/lib/dri/radeonsi_dri.so
#2  0x00007fc8f12d0ef8 in  () at /usr/lib/dri/radeonsi_dri.so
#3  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 3 (Thread 0x7fc900f17700 (LWP 2130)):
#0  0x00007fc92339ba76 in ppoll () at /usr/lib/libc.so.6
#1  0x00007fc9207686f3 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007fc920769e8f in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007fc92070ed0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007fc92051e78e in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007fc91ae28a19 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007fc920523b2d in  () at /usr/lib/libQt5Core.so.5
#7  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7fc9033f8700 (LWP 2106)):
#0  0x00007fc92339ba76 in ppoll () at /usr/lib/libc.so.6
#1  0x00007fc9207686f3 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007fc920769e8f in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007fc92070ed0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007fc92051e78e in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007fc919cb1416 in  () at /usr/lib/libQt5DBus.so.5
#6  0x00007fc920523b2d in  () at /usr/lib/libQt5Core.so.5
#7  0x00007fc91c35708c in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007fc9233a5e7f in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7fc923a2f840 (LWP 2066)):
[KCrash Handler]
#5  0x00007fc8f16ad836 in  () at /usr/lib/dri/radeonsi_dri.so
#6  0x00007fc8f16afbb3 in  () at /usr/lib/dri/radeonsi_dri.so
#7  0x00007fc8f140c613 in  () at /usr/lib/dri/radeonsi_dri.so
#8  0x00007fc8f140a6bf in  () at /usr/lib/dri/radeonsi_dri.so
#9  0x00007fc8f140ab65 in  () at /usr/lib/dri/radeonsi_dri.so
#10 0x00007fc8f120d6e7 in  () at /usr/lib/dri/radeonsi_dri.so
#11 0x00007fc8f136b37a in  () at /usr/lib/dri/radeonsi_dri.so
#12 0x00007fc8f2f76533 in  () at /usr/lib/libGLX_mesa.so.0
#13 0x00007fc908c83165 in  () at /usr/lib/qt/plugins/xcbglintegrations/libqxcb-glx-integration.so
#14 0x00007fc920cbd38f in QOpenGLContext::swapBuffers(QSurface*) () at /usr/lib/libQt5Gui.so.5
#15 0x00007fc91b50a400 in  () at /usr/lib/libQt5Quick.so.5
#16 0x00007fc91b587686 in QQuickWindow::event(QEvent*) () at /usr/lib/libQt5Quick.so.5
#17 0x00007fc83b95ac64 in PlasmaQuick::Dialog::event(QEvent*) () at /usr/lib/libKF5PlasmaQuick.so.5
#18 0x00007fc92148ae3c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#19 0x00007fc921492816 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#20 0x00007fc9207106c0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#21 0x00007fc920c8d7f3 in QWindowPrivate::deliverUpdateRequest() () at /usr/lib/libQt5Gui.so.5
#22 0x00007fc920c8dd2b in QWindow::event(QEvent*) () at /usr/lib/libQt5Gui.so.5
#23 0x00007fc91b587626 in QQuickWindow::event(QEvent*) () at /usr/lib/libQt5Quick.so.5
#24 0x00007fc83b95ac64 in PlasmaQuick::Dialog::event(QEvent*) () at /usr/lib/libKF5PlasmaQuick.so.5
#25 0x00007fc92148ae3c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#26 0x00007fc921492816 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#27 0x00007fc9207106c0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#28 0x00007fc92076bfb8 in QTimerInfoList::activateTimers() () at /usr/lib/libQt5Core.so.5
#29 0x00007fc92076a0f4 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#30 0x00007fc90ac1058e in  () at /usr/lib/libQt5XcbQpa.so.5
#31 0x00007fc92070ed0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#32 0x00007fc920717ff8 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#33 0x00007fc92366f719 in kdemain () at /usr/lib/libkdeinit5_kwin_x11.so
#34 0x00007fc9232d0f4a in __libc_start_main () at /usr/lib/libc.so.6
#35 0x000055577d59876a in _start ()

Reported using DrKonqi