Application: kwin_x11 (5.9.5)

Qt Version: 5.8.0
Frameworks Version: 5.34.0
Operating System: Linux 4.11.1-1-MANJARO x86_64
Distribution: "Manjaro Linux"

-- Information about the crash:
- What I was doing when the application crashed:
There's around 30% chance kwin crashes when I try to open virtualbox.

The crash can be reproduced sometimes.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f2a7967f840 (LWP 917))]

Thread 6 (Thread 0x7f2a562f5700 (LWP 1083)):
#0  0x00007f2a790d876b in ppoll () at /usr/lib/libc.so.6
#1  0x00007f2a7675c329 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007f2a7675d99a in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007f2a7670a8ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f2a7652ca73 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007f2a71045025 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007f2a765316d8 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f2a7231e2e7 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007f2a790e254f in clone () at /usr/lib/libc.so.6

Thread 5 (Thread 0x7f2a41770700 (LWP 1049)):
#0  0x00007f2a72324756 in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007f2a7569b234 in  () at /usr/lib/libQt5Script.so.5
#2  0x00007f2a7569b279 in  () at /usr/lib/libQt5Script.so.5
#3  0x00007f2a7231e2e7 in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007f2a790e254f in clone () at /usr/lib/libc.so.6

Thread 4 (Thread 0x7f2a57346700 (LWP 1025)):
#0  0x00007f2a790d876b in ppoll () at /usr/lib/libc.so.6
#1  0x00007f2a7675c329 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007f2a7675d99a in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007f2a7670a8ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f2a7652ca73 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007f2a71045025 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007f2a765316d8 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f2a7231e2e7 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007f2a790e254f in clone () at /usr/lib/libc.so.6

Thread 3 (Thread 0x7f2a5dbb6700 (LWP 959)):
#0  0x00007f2a790d876b in ppoll () at /usr/lib/libc.so.6
#1  0x00007f2a7675c329 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007f2a7675d99a in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007f2a7670a8ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f2a7652ca73 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007f2a701ef125 in  () at /usr/lib/libQt5DBus.so.5
#6  0x00007f2a765316d8 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007f2a7231e2e7 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007f2a790e254f in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7f2a5fa92700 (LWP 941)):
#0  0x00007f2a790d867d in poll () at /usr/lib/libc.so.6
#1  0x00007f2a781f18e0 in  () at /usr/lib/libxcb.so.1
#2  0x00007f2a781f3679 in xcb_wait_for_event () at /usr/lib/libxcb.so.1
#3  0x00007f2a60b6e239 in  () at /usr/lib/libQt5XcbQpa.so.5
#4  0x00007f2a765316d8 in  () at /usr/lib/libQt5Core.so.5
#5  0x00007f2a7231e2e7 in start_thread () at /usr/lib/libpthread.so.0
#6  0x00007f2a790e254f in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7f2a7967f840 (LWP 917)):
[KCrash Handler]
#6  0x0000000000000020 in  ()
#7  0x00007f2a7673e420 in QObject::connect(QObject const*, char const*, QObject const*, char const*, Qt::ConnectionType) () at /usr/lib/libQt5Core.so.5
#8  0x00007f2a756dd76f in  () at /usr/lib/libQt5Script.so.5
#9  0x00007f2a756dd844 in  () at /usr/lib/libQt5Script.so.5
#10 0x00007f2a756ddac2 in QScriptEngine::newQObject(QObject*, QScriptEngine::ValueOwnership, QFlags<QScriptEngine::QObjectWrapOption> const&) () at /usr/lib/libQt5Script.so.5
#11 0x00007f2a78ccee7c in  () at /usr/lib/libkwin.so.5
#12 0x00007f2a756ddd75 in  () at /usr/lib/libQt5Script.so.5
#13 0x00007f2a75706826 in  () at /usr/lib/libQt5Script.so.5
#14 0x00007f2a7570eaf1 in  () at /usr/lib/libQt5Script.so.5
#15 0x00007f2a76737f14 in QMetaObject::activate(QObject*, int, int, void**) () at /usr/lib/libQt5Core.so.5
#16 0x00007f2a75eece08 in KWin::EffectsHandler::desktopPresenceChanged(KWin::EffectWindow*, int, int) () at /usr/lib/libkwineffects.so.10
#17 0x00007f2a75eee7c1 in  () at /usr/lib/libkwineffects.so.10
#18 0x00007f2a76738bd9 in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#19 0x00007f2a773ee34c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#20 0x00007f2a773f5b61 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#21 0x00007f2a7670c470 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#22 0x00007f2a7670ebfd in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5
#23 0x00007f2a7675d7c7 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#24 0x00007f2a60bceded in  () at /usr/lib/libQt5XcbQpa.so.5
#25 0x00007f2a7670a8ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#26 0x00007f2a76712e14 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#27 0x00007f2a793a3391 in kdemain () at /usr/lib/libkdeinit5_kwin_x11.so
#28 0x00007f2a79016511 in __libc_start_main () at /usr/lib/libc.so.6
#29 0x000000000040069a in _start ()

Reported using DrKonqi