Application: kwin_x11 (5.2.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-21-generic x86_64
Distribution: Ubuntu 15.04

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

The login screen looks normal all three monitors display everything they should, then upon entering the password and logging in, kwin reports the crash after several attempts..

The resolution of the ticket 343844 states something regarding qt5.5 which i upgraded from the backports but with the same outcome, i have since reverted the backports upgrade of plasma 5.3 and qt5.5 as plasma seemed unstable and the login screen layout was all messed up.

I am using two Nvidia Quadro NVS 285's

The crash can be reproduced every time.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[KCrash Handler]
#6  xcb_setup_vendor_end (R=R@entry=0x0) at xproto.c:1569
#7  0x00007efe1fef1059 in xcb_setup_pixmap_formats_iterator (R=R@entry=0x0) at xproto.c:1622
#8  0x00007efe1fef1099 in xcb_setup_roots_iterator (R=0x0) at xproto.c:1659
#9  0x00007efe217110f8 in defaultScreen () at ../libkwineffects/kwinglobals.h:170
#10 KWin::ColorMapper::ColorMapper (this=this@entry=0x147b9c0, parent=parent@entry=0x1445900) at ../workspace.cpp:82
#11 0x00007efe21719371 in KWin::Workspace::Workspace (this=0x1445900, restore=<optimized out>) at ../workspace.cpp:172
#12 0x00007efe21ebeaa6 in operator() (__closure=<synthetic pointer>) at ../main_x11.cpp:170
#13 call (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:494
#14 call<QtPrivate::List<>, void> (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:551
#15 QtPrivate::QFunctorSlotObject<KWin::ApplicationX11::performStartup()::<lambda()>, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=<optimized out>, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject_impl.h:192
#16 0x00007efe2041435a in call (a=0x7ffcff0720c0, r=0x13b9440, this=0x13b8650) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#17 QMetaObject::activate (sender=0x13b9440, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x0) at kernel/qobject.cpp:3702
#18 0x00007efe20415057 in QMetaObject::activate (sender=<optimized out>, m=m@entry=0x7efe21489bc0 <KSelectionOwner::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x0) at kernel/qobject.cpp:3582
#19 0x00007efe212790e3 in KSelectionOwner::claimedOwnership (this=<optimized out>) at moc_kselectionowner.cpp:150
#20 0x00007efe2125ca9b in KSelectionOwner::Private::claimSucceeded (this=0x13c2e80) at ../../src/kselectionowner.cpp:206
#21 0x00007efe2125d221 in KSelectionOwner::filterEvent (this=0x13b9440, ev_P=<optimized out>) at ../../src/kselectionowner.cpp:424
#22 0x00007efe203e0510 in QAbstractEventDispatcher::filterNativeEvent (this=this@entry=0x138f300, eventType=..., message=message@entry=0x7efe04001aa0, result=result@entry=0x7ffcff072258) at kernel/qabstracteventdispatcher.cpp:460
#23 0x00007efe0b50502d in QXcbConnection::handleXcbEvent (this=this@entry=0x135aa60, event=event@entry=0x7efe04001aa0) at qxcbconnection.cpp:863
#24 0x00007efe0b5064bb in QXcbConnection::processXcbEvents (this=0x135aa60) at qxcbconnection.cpp:1303
#25 0x00007efe2041573a in QObject::event (this=0x135aa60, e=<optimized out>) at kernel/qobject.cpp:1245
#26 0x00007efe20cedb2c in QApplicationPrivate::notify_helper (this=0x134bb50, receiver=0x135aa60, e=0x7efe04002210) at kernel/qapplication.cpp:3720
#27 0x00007efe20cf3000 in QApplication::notify (this=0x7ffcff072940, receiver=0x135aa60, e=0x7efe04002210) at kernel/qapplication.cpp:3503
#28 0x00007efe203e3c2b in QCoreApplication::notifyInternal (this=0x7ffcff072940, receiver=0x135aa60, event=event@entry=0x7efe04002210) at kernel/qcoreapplication.cpp:935
#29 0x00007efe203e5c9b in sendEvent (event=0x7efe04002210, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#30 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x133c4b0) at kernel/qcoreapplication.cpp:1552
#31 0x00007efe2043a112 in QEventDispatcherUNIX::processEvents (this=0x138f300, flags=flags@entry=...) at kernel/qeventdispatcher_unix.cpp:579
#32 0x00007efe0b55c96d in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#33 0x00007efe203e13e2 in QEventLoop::exec (this=this@entry=0x7ffcff072860, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#34 0x00007efe203e902c in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#35 0x00007efe2072831c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1510
#36 0x00007efe20ce97a5 in QApplication::exec () at kernel/qapplication.cpp:2956
#37 0x00007efe21ebf8c3 in kdemain (argc=3, argv=0x7ffcff072a98) at ../main_x11.cpp:294
#38 0x00007efe21b11a40 in __libc_start_main (main=0x400790 <main(int, char**)>, argc=3, argv=0x7ffcff072a98, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffcff072a88) at libc-start.c:289
#39 0x00000000004007c9 in _start ()

Reported using DrKonqi