Application: kwin_x11 (5.2.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-15-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
- What I was doing when the application crashed:
Ctrl-Alt-F7 to switch back from a parallel Unity desktop session.

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".
[Current thread is 1 (Thread 0x7f46d096e800 (LWP 16220))]

Thread 5 (Thread 0x7f46ae1d7700 (LWP 16244)):
#0  0x00007f46d04338dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f46c7548ebc in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f46c7549242 in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f46b28f0ae6 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
#4  0x00007f46c756f955 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f46c7a676aa in start_thread (arg=0x7f46ae1d7700) at pthread_create.c:333
#6  0x00007f46d043eeed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 4 (Thread 0x7f46ad9d6700 (LWP 16245)):
#0  0x00007f46d04338dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f46c7548ebc in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f46c7548fcc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f46c7549009 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f46c756f955 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f46c7a676aa in start_thread (arg=0x7f46ad9d6700) at pthread_create.c:333
#6  0x00007f46d043eeed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7f469e665700 (LWP 16255)):
#0  0x00007f46d0435743 in select () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f46cec7f101 in qt_safe_select (nfds=24, fdread=fdread@entry=0x7f4690000a78, fdwrite=fdwrite@entry=0x7f4690000d08, fdexcept=fdexcept@entry=0x7f4690000f98, orig_timeout=orig_timeout@entry=0x0) at kernel/qcore_unix.cpp:75
#2  0x00007f46cec80cd2 in select (timeout=0x0, exceptfds=0x7f4690000f98, writefds=0x7f4690000d08, readfds=0x7f4690000a78, nfds=<optimized out>, this=0x7f46900008c0) at kernel/qeventdispatcher_unix.cpp:320
#3  QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7f46900008e0, flags=..., flags@entry=..., timeout=timeout@entry=0x0) at kernel/qeventdispatcher_unix.cpp:196
#4  0x00007f46cec81275 in QEventDispatcherUNIX::processEvents (this=0x7f46900008c0, flags=...) at kernel/qeventdispatcher_unix.cpp:607
#5  0x00007f46cec283e2 in QEventLoop::exec (this=this@entry=0x7f469e664da0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007f46ce9e7b44 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#7  0x00007f46c889af65 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8  0x00007f46ce9ecb0e in QThreadPrivate::start (arg=0x1842db0) at thread/qthread_unix.cpp:337
#9  0x00007f46c7a676aa in start_thread (arg=0x7f469e665700) at pthread_create.c:333
#10 0x00007f46d043eeed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f468bff7700 (LWP 16311)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f46cd7f1644 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#2  0x00007f46cd7f1689 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#3  0x00007f46c7a676aa in start_thread (arg=0x7f468bff7700) at pthread_create.c:333
#4  0x00007f46d043eeed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f46d096e800 (LWP 16220)):
[KCrash Handler]
#6  __memcpy_avx_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S:204
#7  0x00007f46c8ceb516 in KWin::GLVertexBuffer::setData (this=this@entry=0x17b8690, vertexCount=36, dim=dim@entry=2, vertices=0x2058c18, texcoords=texcoords@entry=0x0) at ../../libkwineffects/kwinglutils.cpp:2242
#8  0x00007f46cfffad3d in KWin::SceneOpenGL2::doPaintBackground (this=<optimized out>, vertices=...) at ../scene_opengl.cpp:1039
#9  0x00007f46d0000475 in KWin::SceneOpenGL::paintBackground (this=this@entry=0x17ff7d0, region=...) at ../scene_opengl.cpp:732
#10 0x00007f46cffe9e6c in KWin::Scene::paintSimpleScreen (this=this@entry=0x17ff7d0, orig_mask=orig_mask@entry=8, region=...) at ../scene.cpp:369
#11 0x00007f46cfffa513 in KWin::SceneOpenGL2::paintSimpleScreen (this=this@entry=0x17ff7d0, mask=mask@entry=8, region=...) at ../scene_opengl.cpp:1005
#12 0x00007f46cffe7205 in KWin::Scene::finalPaintScreen (this=0x17ff7d0, mask=mask@entry=8, region=..., data=...) at ../scene.cpp:199
#13 0x00007f46d001dcff in KWin::EffectsHandlerImpl::paintScreen (this=0x1807800, mask=mask@entry=8, region=..., data=...) at ../effects.cpp:393
#14 0x00007f46ce1f857f in KWin::Effect::paintScreen (this=this@entry=0x1771960, mask=mask@entry=8, region=..., data=...) at ../../libkwineffects/kwineffects.cpp:535
#15 0x00007f46d001dcad in KWin::EffectsHandlerImpl::paintScreen (this=0x1807800, mask=mask@entry=8, region=..., data=...) at ../effects.cpp:390
#16 0x00007f46ce1f857f in KWin::Effect::paintScreen (this=this@entry=0x1766ee0, mask=mask@entry=8, region=..., data=...) at ../../libkwineffects/kwineffects.cpp:535
#17 0x00007f46d001dcad in KWin::EffectsHandlerImpl::paintScreen (this=0x1807800, mask=8, region=..., data=...) at ../effects.cpp:390
#18 0x00007f46cffe6e6a in KWin::Scene::paintScreen (this=this@entry=0x17ff7d0, mask=mask@entry=0x7ffe287ce61c, damage=..., repaint=..., updateRegion=updateRegion@entry=0x7ffe287ce630, validRegion=validRegion@entry=0x7ffe287ce640) at ../scene.cpp:149
#19 0x00007f46d0000da7 in KWin::SceneOpenGL::paint (this=0x17ff7d0, damage=..., toplevels=...) at ../scene_opengl.cpp:651
#20 0x00007f46cffe0973 in KWin::Compositor::performCompositing (this=0x1754a10) at ../composite.cpp:658
#21 0x00007f46cec5c6f3 in QObject::event (this=0x1754a10, e=<optimized out>) at kernel/qobject.cpp:1267
#22 0x00007f46cf534b2c in QApplicationPrivate::notify_helper (this=0x14b7710, receiver=0x1754a10, e=0x7ffe287cea50) at kernel/qapplication.cpp:3720
#23 0x00007f46cf53a000 in QApplication::notify (this=0x7ffe287cec90, receiver=0x1754a10, e=0x7ffe287cea50) at kernel/qapplication.cpp:3503
#24 0x00007f46cec2ac2b in QCoreApplication::notifyInternal (this=0x7ffe287cec90, receiver=0x1754a10, event=event@entry=0x7ffe287cea50) at kernel/qcoreapplication.cpp:935
#25 0x00007f46cec82ae5 in sendEvent (event=0x7ffe287cea50, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#26 QTimerInfoList::activateTimers (this=0x157d7a8) at kernel/qtimerinfo_unix.cpp:635
#27 0x00007f46cec806a0 in QEventDispatcherUNIX::activateTimers (this=this@entry=0x14a4a50) at kernel/qeventdispatcher_unix.cpp:549
#28 0x00007f46cec81243 in QEventDispatcherUNIX::processEvents (this=0x14a4a50, flags=flags@entry=...) at kernel/qeventdispatcher_unix.cpp:611
#29 0x00007f46b9c0396d in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#30 0x00007f46cec283e2 in QEventLoop::exec (this=this@entry=0x7ffe287cebb0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#31 0x00007f46cec3002c in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#32 0x00007f46cef6f31c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1510
#33 0x00007f46cf5307a5 in QApplication::exec () at kernel/qapplication.cpp:2956
#34 0x00007f46d07068c3 in kdemain (argc=1, argv=0x7ffe287cede8) at ../main_x11.cpp:294
#35 0x00007f46d0358a40 in __libc_start_main (main=0x400790 <main(int, char**)>, argc=1, argv=0x7ffe287cede8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe287cedd8) at libc-start.c:289
#36 0x00000000004007c9 in _start ()

Reported using DrKonqi