Application: kwin_x11 (5.12.7)

Qt Version: 5.9.5
Frameworks Version: 5.44.0
Operating System: Linux 4.15.0-42-generic x86_64
Distribution: Ubuntu 18.04.2 LTS

-- Information about the crash:
- What I was doing when the application crashed:
I moved my mouse to the top-right of the screen to activate the screen corner that I set up to present all windows on the current desktop. It showed all my open windows as usual, but crashed right after.

The crash does not seem to be reproducible.

-- 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 0x7faddc6f8cc0 (LWP 4327))]

Thread 5 (Thread 0x7fadabfff700 (LWP 4989)):
#0  0x00007faddc060cf6 in __GI_ppoll (fds=0x7fada4000d68, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39
#1  0x00007fadd94625c1 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fadd9463cde in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fadd940b9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fadd922a22a in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fadd3bb26f5 in  () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#6  0x00007fadd922f16d in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fadd50c66db in start_thread (arg=0x7fadabfff700) at pthread_create.c:463
#8  0x00007faddc06d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7fada3512700 (LWP 4445)):
#0  0x00007fadd50cc9f3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x7fadd8663fb8) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
#1  0x00007fadd50cc9f3 in __pthread_cond_wait_common (abstime=0x0, mutex=0x7fadd8663f68, cond=0x7fadd8663f90) at pthread_cond_wait.c:502
#2  0x00007fadd50cc9f3 in __pthread_cond_wait (cond=0x7fadd8663f90, mutex=0x7fadd8663f68) at pthread_cond_wait.c:655
#3  0x00007fadd836d5f4 in  () at /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#4  0x00007fadd836d639 in  () at /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#5  0x00007fadd50c66db in start_thread (arg=0x7fada3512700) at pthread_create.c:463
#6  0x00007faddc06d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7fadb9727700 (LWP 4402)):
#0  0x00007faddc060cf6 in __GI_ppoll (fds=0x7fadb0000d28, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39
#1  0x00007fadd94625c1 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fadd9463cde in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fadd940b9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fadd922a22a in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fadd3bb26f5 in  () at /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#6  0x00007fadd922f16d in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fadd50c66db in start_thread (arg=0x7fadb9727700) at pthread_create.c:463
#8  0x00007faddc06d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fadbbdf5700 (LWP 4350)):
#0  0x00007faddc060cf6 in __GI_ppoll (fds=0x7fadb400b2a8, nfds=1, timeout=<optimized out>, sigmask=0x0) at ../sysdeps/unix/sysv/linux/ppoll.c:39
#1  0x00007fadd94625c1 in qt_safe_poll(pollfd*, unsigned long, timespec const*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2  0x00007fadd9463cde in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3  0x00007fadd940b9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007fadd922a22a in QThread::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007fadd2a8bd45 in  () at /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
#6  0x00007fadd922f16d in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007fadd50c66db in start_thread (arg=0x7fadbbdf5700) at pthread_create.c:463
#8  0x00007faddc06d88f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7faddc6f8cc0 (LWP 4327)):
[KCrash Handler]
#6  0x000055d127145fd0 in  ()
#7  0x00007faddbb683aa in KWin::Workspace::workspaceEvent(xcb_generic_event_t*) () at /usr/lib/x86_64-linux-gnu/libkwin.so.5
#8  0x00007fadd940a58f in QAbstractEventDispatcher::filterNativeEvent(QByteArray const&, void*, long*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007fadc34fa820 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#10 0x00007fadc34fb4ac in QXcbConnection::processXcbEvents() () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#11 0x00007fadd943d122 in QObject::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007fadda18b82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#13 0x00007fadda1930f4 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#14 0x00007fadd940d9a8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007fadd941011d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#16 0x00007fadd9463af4 in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#17 0x00007fadc355c5cd in  () at /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#18 0x00007fadd940b9ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007fadd9414a84 in QCoreApplication::exec() () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00007faddc345dbb in kdemain(int, char**) (argc=<optimized out>, argv=0x7ffc913cba28) at ./main_x11.cpp:468
#21 0x00007faddbf6db97 in __libc_start_main (main=0x55d125265730 <main>, argc=3, argv=0x7ffc913cba28, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffc913cba18) at ../csu/libc-start.c:310
#22 0x000055d12526576a in _start ()

Reported using DrKonqi