Application: kwin_x11 (5.8.3)

Qt Version: 5.7.0
Frameworks Version: 5.27.0
Operating System: Linux 4.8.6-1-ARCH x86_64
Distribution: "Arch Linux"

-- Information about the crash:
I have opened a .mp4 video with mpv on archlinux

%mpv --version                                                                                                                                                                                         mpv 0.21.0 (C) 2000-2016 mpv/MPlayer/mplayer2 projects
 built on Sun Oct 30 17:49:09 CET 2016
ffmpeg library versions:
   libavutil       55.34.100
   libavcodec      57.64.100
   libavformat     57.56.100
   libswscale      4.2.100
   libavfilter     6.65.100
   libswresample   2.3.100
ffmpeg version: 3.2

crash happened an istant after trying to skip video forward/backward by pressing right/left arrow key

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 0x7faad8df1840 (LWP 25432))]

Thread 6 (Thread 0x7faa9bcc6700 (LWP 25463)):
[KCrash Handler]
#6  0x00007faad5e302d2 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007faad5dcd856 in QLockFile::tryLock(int) () at /usr/lib/libQt5Core.so.5
#8  0x00007faad7bd62d9 in  () at /usr/lib/libKF5ConfigCore.so.5
#9  0x00007faad7bba2b0 in KConfig::sync() () at /usr/lib/libKF5ConfigCore.so.5
#10 0x00007faab7ddfdf5 in  () at /usr/lib/qt/plugins/org.kde.kwin.platforms/KWinX11Platform.so
#11 0x00007faad5ec89ce in QMetaObject::activate(QObject*, int, int, void**) () at /usr/lib/libQt5Core.so.5
#12 0x00007faad5ed56d8 in QTimer::timerEvent(QTimerEvent*) () at /usr/lib/libQt5Core.so.5
#13 0x00007faad5ec9473 in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#14 0x00007faad6b7ce0c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#15 0x00007faad6b84581 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#16 0x00007faad5e9cde0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#17 0x00007faad5ef06ae in QTimerInfoList::activateTimers() () at /usr/lib/libQt5Core.so.5
#18 0x00007faad5eee618 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#19 0x00007faad5e9b23a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#20 0x00007faad5cbe0f3 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#21 0x00007faad5cc2d78 in  () at /usr/lib/libQt5Core.so.5
#22 0x00007faad1ae9454 in start_thread () at /usr/lib/libpthread.so.0
#23 0x00007faad88457df in clone () at /usr/lib/libc.so.6

Thread 5 (Thread 0x7faa9d05a700 (LWP 25459)):
#0  0x00007faad883c551 in ppoll () at /usr/lib/libc.so.6
#1  0x00007faad5eecac9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007faad5eee3b8 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007faad5e9b23a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007faad5cbe0f3 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007faad08442d5 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007faad5cc2d78 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007faad1ae9454 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007faad88457df in clone () at /usr/lib/libc.so.6

Thread 4 (Thread 0x7faab69b0700 (LWP 25458)):
#0  0x00007faad883c551 in ppoll () at /usr/lib/libc.so.6
#1  0x00007faad5eecac9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007faad5eee3b8 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007faad5e9b23a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007faad5cbe0f3 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007faad08442d5 in  () at /usr/lib/libQt5Qml.so.5
#6  0x00007faad5cc2d78 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007faad1ae9454 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007faad88457df in clone () at /usr/lib/libc.so.6

Thread 3 (Thread 0x7faabc83a700 (LWP 25436)):
#0  0x00007faad883c551 in ppoll () at /usr/lib/libc.so.6
#1  0x00007faad5eecac9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/libQt5Core.so.5
#2  0x00007faad5eee3b8 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#3  0x00007faad5e9b23a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007faad5cbe0f3 in QThread::exec() () at /usr/lib/libQt5Core.so.5
#5  0x00007faacfa0ee55 in  () at /usr/lib/libQt5DBus.so.5
#6  0x00007faad5cc2d78 in  () at /usr/lib/libQt5Core.so.5
#7  0x00007faad1ae9454 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007faad88457df in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7faabe75b700 (LWP 25435)):
#0  0x00007faad883c48d in poll () at /usr/lib/libc.so.6
#1  0x00007faad797f8e0 in  () at /usr/lib/libxcb.so.1
#2  0x00007faad7981679 in xcb_wait_for_event () at /usr/lib/libxcb.so.1
#3  0x00007faabf207449 in  () at /usr/lib/libQt5XcbQpa.so.5
#4  0x00007faad5cc2d78 in  () at /usr/lib/libQt5Core.so.5
#5  0x00007faad1ae9454 in start_thread () at /usr/lib/libpthread.so.0
#6  0x00007faad88457df in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7faad8df1840 (LWP 25432)):
#0  0x00007faad1aef10f in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007faad797fb57 in  () at /usr/lib/libxcb.so.1
#2  0x00007faad798139f in  () at /usr/lib/libxcb.so.1
#3  0x00007faad79814b2 in xcb_wait_for_reply () at /usr/lib/libxcb.so.1
#4  0x00007faad837d155 in  () at /usr/lib/libkwin.so.5
#5  0x00007faad837e118 in  () at /usr/lib/libkwin.so.5
#6  0x00007faad837ee20 in  () at /usr/lib/libkwin.so.5
#7  0x00007faad83cf3c5 in KWin::Toplevel::getShadow() () at /usr/lib/libkwin.so.5
#8  0x00007faad83d3d21 in KWin::Scene::windowAdded(KWin::Toplevel*) () at /usr/lib/libkwin.so.5
#9  0x00007faad83c75f8 in  () at /usr/lib/libkwin.so.5
#10 0x00007faad83c7b7e in KWin::Client::setupCompositing() () at /usr/lib/libkwin.so.5
#11 0x00007faad83c95f0 in KWin::Compositor::startupWithWorkspace() () at /usr/lib/libkwin.so.5
#12 0x00007faad83ca3d3 in KWin::Compositor::slotCompositingOptionsInitialized() () at /usr/lib/libkwin.so.5
#13 0x00007faad83ca902 in KWin::Compositor::setup() () at /usr/lib/libkwin.so.5
#14 0x00007faad5ec94b9 in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5
#15 0x00007faad6b7ce0c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#16 0x00007faad6b84581 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#17 0x00007faad5e9cde0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#18 0x00007faad5e9f56d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5
#19 0x00007faad5eee1fa in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#20 0x00007faabf2800dd in  () at /usr/lib/libQt5XcbQpa.so.5
#21 0x00007faad5e9b23a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#22 0x00007faad5ea373c in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#23 0x00007faad8b04495 in kdemain () at /usr/lib/libkdeinit5_kwin_x11.so
#24 0x00007faad877d291 in __libc_start_main () at /usr/lib/libc.so.6
#25 0x000000000040069a in _start ()

Reported using DrKonqi