Application: kwin_x11 (5.2.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-22-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
- What I was doing when the application crashed:
Changing users or logging off when you are in a second session

- Unusual behavior I noticed:
The video buffer is shown with some strange geometric shapes, pices of windows are visible in these geometric shapes

- Custom settings of the application:
I use the NVida propriatary driver

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 0x7fa7b0490800 (LWP 26142))]

Thread 3 (Thread 0x7fa794998700 (LWP 26166)):
#0  0x00007fa7aff6b743 in select () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fa7ae7b5101 in qt_safe_select (nfds=17, fdread=fdread@entry=0x7fa780000a98, fdwrite=fdwrite@entry=0x7fa780000d28, fdexcept=fdexcept@entry=0x7fa780000fb8, orig_timeout=orig_timeout@entry=0x0) at kernel/qcore_unix.cpp:75
#2  0x00007fa7ae7b6cd2 in select (timeout=0x0, exceptfds=0x7fa780000fb8, writefds=0x7fa780000d28, readfds=0x7fa780000a98, nfds=<optimized out>, this=0x7fa7800008e0) at kernel/qeventdispatcher_unix.cpp:320
#3  QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7fa780000900, flags=..., flags@entry=..., timeout=timeout@entry=0x0) at kernel/qeventdispatcher_unix.cpp:196
#4  0x00007fa7ae7b7275 in QEventDispatcherUNIX::processEvents (this=0x7fa7800008e0, flags=...) at kernel/qeventdispatcher_unix.cpp:607
#5  0x00007fa7ae75e3e2 in QEventLoop::exec (this=this@entry=0x7fa794997da0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007fa7ae51db44 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#7  0x00007fa7a83d0f65 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8  0x00007fa7ae522b0e in QThreadPrivate::start (arg=0x1895580) at thread/qthread_unix.cpp:337
#9  0x00007fa7a759d6aa in start_thread (arg=0x7fa794998700) at pthread_create.c:333
#10 0x00007fa7aff74eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fa785867700 (LWP 26196)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fa7ad327644 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#2  0x00007fa7ad327689 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#3  0x00007fa7a759d6aa in start_thread (arg=0x7fa785867700) at pthread_create.c:333
#4  0x00007fa7aff74eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fa7b0490800 (LWP 26142)):
[KCrash Handler]
#6  __memcpy_sse2_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S:35
#7  0x00007fa7a8821516 in KWin::GLVertexBuffer::setData (this=this@entry=0x18b7a10, vertexCount=36, dim=dim@entry=2, vertices=0x20f69b8, texcoords=texcoords@entry=0x0) at ../../libkwineffects/kwinglutils.cpp:2242
#8  0x00007fa7afb30d3d in KWin::SceneOpenGL2::doPaintBackground (this=<optimized out>, vertices=...) at ../scene_opengl.cpp:1039
#9  0x00007fa7afb36475 in KWin::SceneOpenGL::paintBackground (this=this@entry=0x1898a40, region=...) at ../scene_opengl.cpp:732
#10 0x00007fa7afb1fe6c in KWin::Scene::paintSimpleScreen (this=this@entry=0x1898a40, orig_mask=orig_mask@entry=8, region=...) at ../scene.cpp:369
#11 0x00007fa7afb30513 in KWin::SceneOpenGL2::paintSimpleScreen (this=this@entry=0x1898a40, mask=mask@entry=8, region=...) at ../scene_opengl.cpp:1005
#12 0x00007fa7afb1d205 in KWin::Scene::finalPaintScreen (this=0x1898a40, mask=mask@entry=8, region=..., data=...) at ../scene.cpp:199
#13 0x00007fa7afb53cff in KWin::EffectsHandlerImpl::paintScreen (this=0x18fb7c0, mask=mask@entry=8, region=..., data=...) at ../effects.cpp:393
#14 0x00007fa7add2e57f in KWin::Effect::paintScreen (this=this@entry=0x17a6f60, mask=mask@entry=8, region=..., data=...) at ../../libkwineffects/kwineffects.cpp:535
#15 0x00007fa7afb53cad in KWin::EffectsHandlerImpl::paintScreen (this=0x18fb7c0, mask=mask@entry=8, region=..., data=...) at ../effects.cpp:390
#16 0x00007fa7add2e57f in KWin::Effect::paintScreen (this=this@entry=0x18ef070, mask=mask@entry=8, region=..., data=...) at ../../libkwineffects/kwineffects.cpp:535
#17 0x00007fa7afb53cad in KWin::EffectsHandlerImpl::paintScreen (this=0x18fb7c0, mask=8, region=..., data=...) at ../effects.cpp:390
#18 0x00007fa7afb1ce6a in KWin::Scene::paintScreen (this=this@entry=0x1898a40, mask=mask@entry=0x7ffe2cd9debc, damage=..., repaint=..., updateRegion=updateRegion@entry=0x7ffe2cd9ded0, validRegion=validRegion@entry=0x7ffe2cd9dee0) at ../scene.cpp:149
#19 0x00007fa7afb36da7 in KWin::SceneOpenGL::paint (this=0x1898a40, damage=..., toplevels=...) at ../scene_opengl.cpp:651
#20 0x00007fa7afb16973 in KWin::Compositor::performCompositing (this=0x1823800) at ../composite.cpp:658
#21 0x00007fa7ae7926f3 in QObject::event (this=0x1823800, e=<optimized out>) at kernel/qobject.cpp:1267
#22 0x00007fa7af06ab2c in QApplicationPrivate::notify_helper (this=0x172ee90, receiver=0x1823800, e=0x7ffe2cd9e2f0) at kernel/qapplication.cpp:3720
#23 0x00007fa7af070000 in QApplication::notify (this=0x7ffe2cd9e530, receiver=0x1823800, e=0x7ffe2cd9e2f0) at kernel/qapplication.cpp:3503
#24 0x00007fa7ae760c2b in QCoreApplication::notifyInternal (this=0x7ffe2cd9e530, receiver=0x1823800, event=event@entry=0x7ffe2cd9e2f0) at kernel/qcoreapplication.cpp:935
#25 0x00007fa7ae7b8ae5 in sendEvent (event=0x7ffe2cd9e2f0, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#26 QTimerInfoList::activateTimers (this=0x1771288) at kernel/qtimerinfo_unix.cpp:635
#27 0x00007fa7ae7b66a0 in QEventDispatcherUNIX::activateTimers (this=this@entry=0x176f210) at kernel/qeventdispatcher_unix.cpp:549
#28 0x00007fa7ae7b7243 in QEventDispatcherUNIX::processEvents (this=0x176f210, flags=flags@entry=...) at kernel/qeventdispatcher_unix.cpp:611
#29 0x00007fa7998d696d in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#30 0x00007fa7ae75e3e2 in QEventLoop::exec (this=this@entry=0x7ffe2cd9e450, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#31 0x00007fa7ae76602c in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#32 0x00007fa7aeaa531c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1510
#33 0x00007fa7af0667a5 in QApplication::exec () at kernel/qapplication.cpp:2956
#34 0x00007fa7b023c8c3 in kdemain (argc=1, argv=0x7ffe2cd9e688) at ../main_x11.cpp:294
#35 0x00007fa7afe8ea40 in __libc_start_main (main=0x400790 <main(int, char**)>, argc=3, argv=0x7ffe2cd9e688, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe2cd9e678) at libc-start.c:289
#36 0x00000000004007c9 in _start ()

Reported using DrKonqi