Application: kwin_x11 (5.10.2)

Qt Version: 5.7.1
Frameworks Version: 5.35.0
Operating System: Linux 4.4.0-87-generic x86_64
Distribution: Maui

-- Information about the crash:
Just browsing firefox on 4k screen with VirtualBox open and the Virtualbox apps move up so title bars aren't visible after KWin crashes. Only effect is a screen flash and the apps have moved uo. Easily fixed by moving them down as Kwin restarts instantly

The crash can be reproduced sometimes.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fe5cf931940 (LWP 7190))]

Thread 7 (Thread 0x7fe5c502b700 (LWP 7207)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fe5e34a09fb in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fe5deb3447d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#3  0x00007fe5deb34d55 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#4  0x00007fe5e349fb48 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5c502b700) at pthread_create.c:333
#6  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 6 (Thread 0x7fe5aa7fe700 (LWP 7202)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fe5e28256f4 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#2  0x00007fe5e2825739 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#3  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5aa7fe700) at pthread_create.c:333
#4  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 5 (Thread 0x7fe5b1021700 (LWP 7200)):
#0  0x00007fe5e57e930d in nanosleep () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007fe5e581ad54 in usleep (useconds=<optimized out>) at ../sysdeps/posix/usleep.c:32
#2  0x00007fe5b314dc80 in ?? () from /usr/lib/x86_64-linux-gnu/dri/amdgpu_dri.so
#3  0x00007fe5b2879552 in ?? () from /usr/lib/x86_64-linux-gnu/dri/amdgpu_dri.so
#4  0x00007fe5b28795a5 in ?? () from /usr/lib/x86_64-linux-gnu/dri/amdgpu_dri.so
#5  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5b1021700) at pthread_create.c:333
#6  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 4 (Thread 0x7fe5c603c700 (LWP 7198)):
#0  0x00007fe5e581870d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007fe5e36bbaaa in qt_safe_poll(pollfd*, unsigned long, timespec const*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fe5e36bd392 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fe5e366b0ba in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fe5e349af64 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fe5de668bf5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#6  0x00007fe5e349fb48 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5c603c700) at pthread_create.c:333
#8  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7fe5ccb8a700 (LWP 7194)):
#0  0x00007fe5e581870d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007fe5e36bbaaa in qt_safe_poll(pollfd*, unsigned long, timespec const*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fe5e36bd392 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fe5e366b0ba in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fe5e349af64 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fe5e5e37735 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
#6  0x00007fe5e349fb48 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5ccb8a700) at pthread_create.c:333
#8  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fe5ce685700 (LWP 7193)):
#0  0x00007fe5e581870d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007fe5e4939c62 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007fe5e493b8d7 in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007fe5cf55cd79 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#4  0x00007fe5e349fb48 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fe5df4fa6ba in start_thread (arg=0x7fe5ce685700) at pthread_create.c:333
#6  0x00007fe5e58243dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fe5cf931940 (LWP 7190)):
[KCrash Handler]
#6  0x00007fe5e3c53b95 in QRegion::operator=(QRegion const&) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#7  0x00007fe5e53836c7 in KWin::Scene::paintScreen(int*, QRegion const&, QRegion const&, QRegion*, QRegion*, QMatrix4x4 const&, QRect const&) () from /usr/lib/x86_64-linux-gnu/libkwin.so.5
#8  0x00007fe5e539b66f in KWin::SceneOpenGL::paint(QRegion, QList<KWin::Toplevel*>) () from /usr/lib/x86_64-linux-gnu/libkwin.so.5
#9  0x00007fe5e5375aae in KWin::Compositor::performCompositing() () from /usr/lib/x86_64-linux-gnu/libkwin.so.5
#10 0x00007fe5e3698d53 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007fe5e3f4becc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#12 0x00007fe5e3f538c6 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#13 0x00007fe5e366d0c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007fe5e36bf68e in QTimerInfoList::activateTimers() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007fe5e36bd602 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#16 0x00007fe5cf5d585d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#17 0x00007fe5e366b0ba in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#18 0x00007fe5e36736cc in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007fe5e5af0142 in kdemain () from /usr/lib/x86_64-linux-gnu/libkdeinit5_kwin_x11.so
#20 0x00007fe5e573d830 in __libc_start_main (main=0x400710, argc=3, argv=0x7ffff16c1528, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffff16c1518) at ../csu/libc-start.c:291
#21 0x0000000000400749 in _start ()

Reported using DrKonqi