Qt Version: 5.12.4
Frameworks Version: 5.62.0
Operating System: Linux 5.3.0-18-generic x86_64
Distribution: Ubuntu 19.10

-- Information about the crash:
My lock screen crashed and this is the first time KWin crashed after my lockscreen crashed.  Pretty sure it's related to bug 413068.

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 0x7fee1c8d5d00 (LWP 5128))]

Thread 6 (Thread 0x7fee088e8700 (LWP 19589)):
#0  futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x560af3b7afa4) at ../sysdeps/unix/sysv/linux/futex-internal.h:80
#1  __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x560af3b7af50, cond=0x560af3b7af78) at pthread_cond_wait.c:508
#2  __pthread_cond_wait (cond=0x560af3b7af78, mutex=0x560af3b7af50) at pthread_cond_wait.c:638
#3  0x00007fee2206fdef in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fee2206fee1 in QWaitCondition::wait(QMutex*, unsigned long) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fee211077b9 in ?? () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#6  0x00007fee21107a1a in ?? () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x00007fee22069cc2 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007fee215d8669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#9  0x00007fee237cd323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 5 (Thread 0x7fee19b49700 (LWP 10607)):
#0  futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x560af401d2b4) at ../sysdeps/unix/sysv/linux/futex-internal.h:80
#1  __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x560af401d260, cond=0x560af401d288) at pthread_cond_wait.c:508
#2  __pthread_cond_wait (cond=0x560af401d288, mutex=0x560af401d260) at pthread_cond_wait.c:638
#3  0x00007fee2206fdef in QWaitCondition::wait(QMutex*, QDeadlineTimer) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fee2206fee1 in QWaitCondition::wait(QMutex*, unsigned long) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fee211077b9 in ?? () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#6  0x00007fee21107a1a in ?? () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x00007fee22069cc2 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007fee215d8669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#9  0x00007fee237cd323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7fee0bbff700 (LWP 5550)):
#0  futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x7fee21c31fb8) at ../sysdeps/unix/sysv/linux/futex-internal.h:80
#1  __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7fee21c31f68, cond=0x7fee21c31f90) at pthread_cond_wait.c:508
#2  __pthread_cond_wait (cond=0x7fee21c31f90, mutex=0x7fee21c31f68) at pthread_cond_wait.c:638
#3  0x00007fee21b3b08a in ?? () from /lib/x86_64-linux-gnu/libQt5Script.so.5
#4  0x00007fee21b3b0af in ?? () from /lib/x86_64-linux-gnu/libQt5Script.so.5
#5  0x00007fee215d8669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#6  0x00007fee237cd323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7fee190ff700 (LWP 5292)):
#0  0x00007fee22286198 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#1  0x00007fee22285b07 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fee2222f63b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fee22068a75 in QThread::exec() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fee20d79319 in ?? () from /lib/x86_64-linux-gnu/libQt5Qml.so.5
#5  0x00007fee22069cc2 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007fee215d8669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#7  0x00007fee237cd323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fee1aff8700 (LWP 5158)):
#0  0x00007fee237c0d26 in __GI_ppoll (fds=0x7fee0c00b4e8, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39
#1  0x00007fee222845f9 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fee22285b64 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fee2222f63b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fee22068a75 in QThread::exec() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fee20704efa in ?? () from /lib/x86_64-linux-gnu/libQt5DBus.so.5
#6  0x00007fee22069cc2 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fee215d8669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#8  0x00007fee237cd323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7fee1c8d5d00 (LWP 5128)):
[KCrash Handler]
#6  0x00007fee21d7a872 in KWin::WindowQuadList::makeInterleavedArrays(unsigned int, KWin::GLVertex2D*, QMatrix4x4 const&) const () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#7  0x00007fee182ab98c in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so
#8  0x00007fee182b3be9 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so
#9  0x00007fee182b3d1b in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so
#10 0x00007fee23481917 in KWin::EffectsHandlerImpl::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#11 0x00007fee21d0e483 in ?? () from /lib/x86_64-linux-gnu/libkwin4_effect_builtins.so.1
#12 0x00007fee234818b7 in KWin::EffectsHandlerImpl::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#13 0x00007fee21c72e6c in ?? () from /lib/x86_64-linux-gnu/libkwin4_effect_builtins.so.1
#14 0x00007fee234818b7 in KWin::EffectsHandlerImpl::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#15 0x00007fee21d7980f in KWin::Effect::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#16 0x00007fee234818b7 in KWin::EffectsHandlerImpl::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#17 0x00007fee21d7980f in KWin::Effect::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#18 0x00007fee234818b7 in KWin::EffectsHandlerImpl::drawWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#19 0x00007fee2351a3df in KWin::Scene::finalPaintWindow(KWin::EffectWindowImpl*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#20 0x00007fee23481750 in KWin::EffectsHandlerImpl::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#21 0x00007fee21d7968f in KWin::Effect::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#22 0x00007fee234816f7 in KWin::EffectsHandlerImpl::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#23 0x00007fee21d7968f in KWin::Effect::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#24 0x00007fee234816f7 in KWin::EffectsHandlerImpl::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#25 0x00007fee21d71c0a in KWin::AnimationEffect::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#26 0x00007fee234816f7 in KWin::EffectsHandlerImpl::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#27 0x00007fee21d71c0a in KWin::AnimationEffect::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#28 0x00007fee234816f7 in KWin::EffectsHandlerImpl::paintWindow(KWin::EffectWindow*, int, QRegion, KWin::WindowPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#29 0x00007fee23520af6 in KWin::Scene::paintWindow(KWin::Scene::Window*, int, QRegion, KWin::WindowQuadList) () from /lib/x86_64-linux-gnu/libkwin.so.5
#30 0x00007fee2351d585 in KWin::Scene::paintSimpleScreen(int, QRegion) () from /lib/x86_64-linux-gnu/libkwin.so.5
#31 0x00007fee182a6b87 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so
#32 0x00007fee235200d0 in KWin::Scene::finalPaintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#33 0x00007fee234814a2 in KWin::EffectsHandlerImpl::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#34 0x00007fee21d795c3 in KWin::Effect::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#35 0x00007fee23481451 in KWin::EffectsHandlerImpl::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#36 0x00007fee21d795c3 in KWin::Effect::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#37 0x00007fee23481451 in KWin::EffectsHandlerImpl::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#38 0x00007fee21d795c3 in KWin::Effect::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#39 0x00007fee23481451 in KWin::EffectsHandlerImpl::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#40 0x00007fee21d795c3 in KWin::Effect::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwineffects.so.12
#41 0x00007fee23481451 in KWin::EffectsHandlerImpl::paintScreen(int, QRegion, KWin::ScreenPaintData&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#42 0x00007fee2351fd83 in KWin::Scene::paintScreen(int*, QRegion const&, QRegion const&, QRegion*, QRegion*, QMatrix4x4 const&, QRect const&) () from /lib/x86_64-linux-gnu/libkwin.so.5
#43 0x00007fee182af4fe in KWin::SceneOpenGL::paint(QRegion, QList<KWin::Toplevel*>) () from /usr/lib/x86_64-linux-gnu/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so
#44 0x00007fee234460a1 in KWin::Compositor::performCompositing() () from /lib/x86_64-linux-gnu/libkwin.so.5
#45 0x00007fee2225ce55 in QObject::event(QEvent*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#46 0x00007fee22c44a86 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#47 0x00007fee22c4de00 in QApplication::notify(QObject*, QEvent*) () from /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#48 0x00007fee22230a9a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#49 0x00007fee22287a00 in QTimerInfoList::activateTimers() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#50 0x00007fee22285cbf in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#51 0x00007fee1c219642 in ?? () from /lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#52 0x00007fee2222f63b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#53 0x00007fee222373a6 in QCoreApplication::exec() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#54 0x00007fee238a6528 in kdemain () from /lib/x86_64-linux-gnu/libkdeinit5_kwin_x11.so
#55 0x00007fee236d21e3 in __libc_start_main (main=0x560af28d0060, argc=1, argv=0x7ffe6ba1c548, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe6ba1c538) at ../csu/libc-start.c:308
#56 0x0000560af28d009e in _start ()
[Inferior 1 (process 5128) detached]

ADDITIONAL INFORMATION
GPU: GTX1060 6GB