Application: kwin_x11 (5.8.6)

Qt Version: 5.6.1
Frameworks Version: 5.33.0
Operating System: Linux 4.4.0-77-generic x86_64
Distribution: Ubuntu 16.04.2 LTS

-- Information about the crash:
- What I was doing when the application crashed:

I had just turned on the computer and logged in via SDDM.

Yesterday I installed the Plasma and Frameworks updates that became available for Ubuntu 16.04 in the Kubuntu Backports PPA. Plasma was updated from 4:5.8.5-0ubuntu2~ubuntu16.04~ppa2 to 4:5.8.6-0ubuntu1~ubuntu16.04~ppa2, and Frameworks were updated from 5.28.0-0ubuntu1~ubuntu16.04~ppa1 to 5.33.0-0ubuntu1~ubuntu16.04~ppa1.

This was the second time I logged into the computer after that upgrade. In the first time, there was no problem. This time, there was this screen informing that KWin had crashed. I didn't try a third time yet to see what would happen.

Despite the crash, KWin was working and I didn't have any problem with my KDE session so far.

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 0x7fa796366940 (LWP 2465))]

Thread 4 (Thread 0x7fa78d5e3700 (LWP 2536)):
#0  0x0000003dd50fc9e3 in select () at ../sysdeps/unix/syscall-template.S:84
#1  0x0000003a610d2bcf in qt_safe_select (nfds=13, fdread=fdread@entry=0x7fa784000a78, fdwrite=fdwrite@entry=0x7fa784000d08, fdexcept=fdexcept@entry=0x7fa784000f98, orig_timeout=orig_timeout@entry=0x0) at kernel/qcore_unix.cpp:75
#2  0x0000003a610d460e in QEventDispatcherUNIX::select (timeout=0x0, exceptfds=0x7fa784000f98, writefds=0x7fa784000d08, readfds=0x7fa784000a78, nfds=<optimized out>, this=0x7fa7840008c0) at kernel/qeventdispatcher_unix.cpp:320
#3  QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7fa7840008e0, flags=..., flags@entry=..., timeout=timeout@entry=0x0) at kernel/qeventdispatcher_unix.cpp:196
#4  0x0000003a610d4b22 in QEventDispatcherUNIX::processEvents (this=0x7fa7840008c0, flags=...) at kernel/qeventdispatcher_unix.cpp:607
#5  0x0000003a6107fffa in QEventLoop::exec (this=this@entry=0x7fa78d5e2c60, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x0000003a60ea89e4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:500
#7  0x0000003a6acc86b5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8  0x0000003a60ead808 in QThreadPrivate::start (arg=0x1a2e280) at thread/qthread_unix.cpp:341
#9  0x0000003dd58076ba in start_thread (arg=0x7fa78d5e3700) at pthread_create.c:333
#10 0x0000003dd510682d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7fa78fb69700 (LWP 2492)):
#0  0x0000003dd50fc9e3 in select () at ../sysdeps/unix/syscall-template.S:84
#1  0x0000003a610d2bcf in qt_safe_select (nfds=8, fdread=fdread@entry=0x7fa788000a78, fdwrite=fdwrite@entry=0x7fa788000d08, fdexcept=fdexcept@entry=0x7fa788000f98, orig_timeout=orig_timeout@entry=0x0) at kernel/qcore_unix.cpp:75
#2  0x0000003a610d460e in QEventDispatcherUNIX::select (timeout=0x0, exceptfds=0x7fa788000f98, writefds=0x7fa788000d08, readfds=0x7fa788000a78, nfds=<optimized out>, this=0x7fa7880008c0) at kernel/qeventdispatcher_unix.cpp:320
#3  QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7fa7880008e0, flags=..., flags@entry=..., timeout=timeout@entry=0x0) at kernel/qeventdispatcher_unix.cpp:196
#4  0x0000003a610d4b22 in QEventDispatcherUNIX::processEvents (this=0x7fa7880008c0, flags=...) at kernel/qeventdispatcher_unix.cpp:607
#5  0x0000003a6107fffa in QEventLoop::exec (this=this@entry=0x7fa78fb68c50, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x0000003a60ea89e4 in QThread::exec (this=this@entry=0x3a61e88d40 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread.cpp:500
#7  0x0000003a61e15515 in QDBusConnectionManager::run (this=0x3a61e88d40 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:189
#8  0x0000003a60ead808 in QThreadPrivate::start (arg=0x3a61e88d40 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:341
#9  0x0000003dd58076ba in start_thread (arg=0x7fa78fb69700) at pthread_create.c:333
#10 0x0000003dd510682d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fa7953a6700 (LWP 2488)):
#0  0x0000003dd50fab5d in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x0000003dd8009c62 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x0000003dd800b8d7 in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007fa795e10d29 in QXcbEventReader::run (this=0x1885170) at qxcbconnection.cpp:1325
#4  0x0000003a60ead808 in QThreadPrivate::start (arg=0x1885170) at thread/qthread_unix.cpp:341
#5  0x0000003dd58076ba in start_thread (arg=0x7fa7953a6700) at pthread_create.c:333
#6  0x0000003dd510682d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fa796366940 (LWP 2465)):
[KCrash Handler]
#6  QtPrivate::QStringList_contains (that=that@entry=0x7fa788007d00, str=..., cs=cs@entry=Qt::CaseSensitive) at tools/qstringlist.cpp:311
#7  0x0000003a61e1ee82 in QStringList::contains (cs=Qt::CaseSensitive, str=..., this=0x7fa788007d00) at ../../include/QtCore/../../src/corelib/tools/qstringlist.h:207
#8  QDBusConnectionPrivate::isServiceRegisteredByThread (this=0x7fa788007c70, serviceName=...) at qdbusintegrator.cpp:2592
#9  0x0000003a61e26b28 in QDBusConnectionPrivate::sendWithReplyAsync (this=0x7fa788007c70, message=..., receiver=receiver@entry=0x0, returnMethod=returnMethod@entry=0x0, errorMethod=errorMethod@entry=0x0, timeout=-1) at qdbusintegrator.cpp:2090
#10 0x0000003a61e161b8 in QDBusConnection::asyncCall (this=<optimized out>, message=..., timeout=<optimized out>) at qdbusconnection.cpp:721
#11 0x00007fa79c6d0b75 in KWin::LogindIntegration::logindServiceRegistered() () from /usr/lib/x86_64-linux-gnu/libkwin.so.5
#12 0x00007fa79c6d1009 in ?? () from /usr/lib/x86_64-linux-gnu/libkwin.so.5
#13 0x0000003a610aec24 in QtPrivate::QSlotObjectBase::call (a=0x7ffea1abc2e0, r=0x190f740, this=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#14 QMetaObject::activate (sender=0x1948020, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffea1abc2e0) at kernel/qobject.cpp:3715
#15 0x0000003a610af1b7 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x3a61e876a0 <QDBusPendingCallWatcher::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7ffea1abc2e0) at kernel/qobject.cpp:3595
#16 0x0000003a61e6bc4f in QDBusPendingCallWatcher::finished (this=<optimized out>, _t1=0x1948020) at .moc/moc_qdbuspendingcall.cpp:152
#17 0x0000003a61e6bd48 in QDBusPendingCallWatcherPrivate::_q_finished (this=<optimized out>) at qdbuspendingcall.cpp:488
#18 QDBusPendingCallWatcher::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at .moc/moc_qdbuspendingcall.cpp:83
#19 0x0000003a610af719 in QObject::event (this=0x1948020, e=<optimized out>) at kernel/qobject.cpp:1256
#20 0x0000003a6215cafc in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x1948020, e=0x7fa78800c960) at kernel/qapplication.cpp:3804
#21 0x0000003a62162036 in QApplication::notify (this=0x7ffea1abc890, receiver=0x1948020, e=0x7fa78800c960) at kernel/qapplication.cpp:3561
#22 0x0000003a610822a8 in QCoreApplication::notifyInternal2 (receiver=0x1948020, event=event@entry=0x7fa78800c960) at kernel/qcoreapplication.cpp:1015
#23 0x0000003a6108416a in QCoreApplication::sendEvent (event=0x7fa78800c960, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:225
#24 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x1860620) at kernel/qcoreapplication.cpp:1650
#25 0x0000003a610d4a02 in QEventDispatcherUNIX::processEvents (this=0x18a8f90, flags=flags@entry=...) at kernel/qeventdispatcher_unix.cpp:579
#26 0x00007fa795e848fd in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#27 0x0000003a6107fffa in QEventLoop::exec (this=this@entry=0x7ffea1abc780, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#28 0x0000003a610886bc in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1285
#29 0x00007fa79ca00226 in kdemain () from /usr/lib/x86_64-linux-gnu/libkdeinit5_kwin_x11.so
#30 0x0000003dd5020830 in __libc_start_main (main=0x400730, argc=3, argv=0x7ffea1abca18, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffea1abca08) at ../csu/libc-start.c:291
#31 0x0000000000400769 in _start ()

Reported using DrKonqi