Application: kwin_x11 (5.7.5)

Qt Version: 5.6.1
Frameworks Version: 5.26.0
Operating System: Linux 4.8.0-28-generic x86_64
Distribution: Ubuntu 16.10

-- Information about the crash:
- What I was doing when the application crashed:
I was working in session of another account. And just prior to crash I switched to my account and logged in. The next thing I saw - was black background and window with crash report.

- Unusual behavior I noticed:
Almost every time I have more than one active (logged in) account, I see lock screen with distortions. See screenshots here - 
1. https://drive.google.com/file/d/0B4r5nJvpzEHGM1FyUXBnZWUyVUk/view
2. https://drive.google.com/file/d/0B4r5nJvpzEHGMHBWNnZucW9Kc0E/view
3. https://drive.google.com/file/d/0B4r5nJvpzEHGWnh2Q1NmSlo0SEE/view
And at this time I saw third screenshot.

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 0x7f839d3fb900 (LWP 5099))]

Thread 4 (Thread 0x7f83876fe700 (LWP 5194)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f83afb07574 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#2  0x00007f83afb075b9 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
#3  0x00007f83ac0c070a in start_thread (arg=0x7f83876fe700) at pthread_create.c:333
#4  0x00007f83b2b240af in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105

Thread 3 (Thread 0x7f838f7fe700 (LWP 5164)):
#0  0x00007f83b2b19ea3 in select () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f83b099bcaf in qt_safe_select (nfds=14, fdread=fdread@entry=0x7f8380000a78, fdwrite=fdwrite@entry=0x7f8380000d08, fdexcept=fdexcept@entry=0x7f8380000f98, orig_timeout=orig_timeout@entry=0x0) at kernel/qcore_unix.cpp:75
#2  0x00007f83b099d754 in QEventDispatcherUNIX::select (timeout=0x0, exceptfds=0x7f8380000f98, writefds=0x7f8380000d08, readfds=0x7f8380000a78, nfds=<optimized out>, this=0x7f83800008c0) at kernel/qeventdispatcher_unix.cpp:320
#3  QEventDispatcherUNIXPrivate::doSelect (this=this@entry=0x7f83800008e0, flags=..., flags@entry=..., timeout=timeout@entry=0x0) at kernel/qeventdispatcher_unix.cpp:196
#4  0x00007f83b099dc6a in QEventDispatcherUNIX::processEvents (this=0x7f83800008c0, flags=...) at kernel/qeventdispatcher_unix.cpp:607
#5  0x00007f83b09480fa in QEventLoop::exec (this=this@entry=0x7f838f7fdca0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007f83b076dd43 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:500
#7  0x00007f83ab21ec65 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8  0x00007f83b0772c68 in QThreadPrivate::start (arg=0x557c2ee7b150) at thread/qthread_unix.cpp:341
#9  0x00007f83ac0c070a in start_thread (arg=0x7f838f7fe700) at pthread_create.c:333
#10 0x00007f83b2b240af in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105

Thread 2 (Thread 0x7f839ce65700 (LWP 5111)):
#0  0x00007f83b2b180bd in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007f83a96219d6 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f83a9621aec in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f83b09a04ab in QEventDispatcherGlib::processEvents (this=0x7f83980008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:419
#4  0x00007f83b09480fa in QEventLoop::exec (this=this@entry=0x7f839ce64c90, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007f83b076dd43 in QThread::exec (this=this@entry=0x7f83b31a1d60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread.cpp:500
#6  0x00007f83b312d575 in QDBusConnectionManager::run (this=0x7f83b31a1d60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:171
#7  0x00007f83b0772c68 in QThreadPrivate::start (arg=0x7f83b31a1d60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:341
#8  0x00007f83ac0c070a in start_thread (arg=0x7f839ce65700) at pthread_create.c:333
#9  0x00007f83b2b240af in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105

Thread 1 (Thread 0x7f839d3fb900 (LWP 5099)):
[KCrash Handler]
#6  KWin::ContrastEffect::uploadRegion (this=this@entry=0x557c2f0ab870, map=@0x7ffe076ae3c8: 0x7f838c17e110, region=...) at ./effects/backgroundcontrast/contrast.cpp:259
#7  0x00007f83afcbafd4 in KWin::ContrastEffect::uploadGeometry (this=this@entry=0x557c2f0ab870, vbo=vbo@entry=0x557c2ee43c70, region=...) at ./effects/backgroundcontrast/contrast.cpp:277
#8  0x00007f83afcbba6e in KWin::ContrastEffect::doContrast (this=this@entry=0x557c2f0ab870, shape=..., screen=..., opacity=3.94778981e-05) at ./effects/backgroundcontrast/contrast.cpp:418
#9  0x00007f83afcbc326 in KWin::ContrastEffect::drawWindow (this=this@entry=0x557c2f0ab870, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects/backgroundcontrast/contrast.cpp:397
#10 0x00007f83b26e06be in KWin::EffectsHandlerImpl::drawWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:506
#11 0x00007f83afc3b882 in KWin::BlurEffect::drawWindow (this=this@entry=0x557c2f0d7e70, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects/blur/blur.cpp:473
#12 0x00007f83b26e06be in KWin::EffectsHandlerImpl::drawWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:506
#13 0x00007f83b011c2b1 in KWin::Effect::drawWindow (this=this@entry=0x557c2f0eb260, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./libkwineffects/kwineffects.cpp:619
#14 0x00007f83b26e06be in KWin::EffectsHandlerImpl::drawWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:506
#15 0x00007f83b011c2b1 in KWin::Effect::drawWindow (this=this@entry=0x557c2f165950, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./libkwineffects/kwineffects.cpp:619
#16 0x00007f83b26e06be in KWin::EffectsHandlerImpl::drawWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:506
#17 0x00007f83b26b1241 in KWin::Scene::finalPaintWindow (this=<optimized out>, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./scene.cpp:607
#18 0x00007f83b26e056a in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:472
#19 0x00007f83afca85e7 in KWin::KscreenEffect::paintWindow (this=this@entry=0x557c2f1278b0, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects/kscreen/kscreen.cpp:116
#20 0x00007f83b26e050e in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:469
#21 0x00007f83b011c151 in KWin::Effect::paintWindow (this=this@entry=0x557c2f0ab870, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./libkwineffects/kwineffects.cpp:589
#22 0x00007f83b26e050e in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:469
#23 0x00007f83b011c151 in KWin::Effect::paintWindow (this=this@entry=0x557c2f0d7e70, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./libkwineffects/kwineffects.cpp:589
#24 0x00007f83b26e050e in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:469
#25 0x00007f83b0128769 in KWin::AnimationEffect::paintWindow (this=this@entry=0x557c2f0eb260, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./libkwineffects/kwinanimationeffect.cpp:644
#26 0x00007f83b26e050e in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:469
#27 0x00007f83afcb2d09 in KWin::SlidingPopupsEffect::paintWindow (this=this@entry=0x557c2f165950, w=w@entry=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects/slidingpopups/slidingpopups.cpp:257
#28 0x00007f83b26e050e in KWin::EffectsHandlerImpl::paintWindow (this=0x557c2f0ab940, w=0x557c2f1e4ec0, mask=mask@entry=6, region=..., data=...) at ./effects.cpp:469
#29 0x00007f83b26b7ad7 in KWin::Scene::paintWindow (this=this@entry=0x557c2ee56590, w=0x557c2f1f1540, mask=6, region=..., quads=...) at ./scene.cpp:479
#30 0x00007f83b26b680e in KWin::Scene::paintSimpleScreen (this=this@entry=0x557c2ee56590, orig_mask=orig_mask@entry=0, region=...) at ./scene.cpp:382
#31 0x00007f83b26c87f3 in KWin::SceneOpenGL2::paintSimpleScreen (this=this@entry=0x557c2ee56590, mask=mask@entry=0, region=...) at ./scene_opengl.cpp:1078
#32 0x00007f83b26b7014 in KWin::Scene::finalPaintScreen (this=0x557c2ee56590, mask=mask@entry=0, region=..., data=...) at ./scene.cpp:201
#33 0x00007f83b26e02ef in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=mask@entry=0, region=..., data=...) at ./effects.cpp:429
#34 0x00007f83b011c09f in KWin::Effect::paintScreen (this=this@entry=0x557c2f1278b0, mask=mask@entry=0, region=..., data=...) at ./libkwineffects/kwineffects.cpp:574
#35 0x00007f83b26e029a in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=mask@entry=0, region=..., data=...) at ./effects.cpp:426
#36 0x00007f83b011c09f in KWin::Effect::paintScreen (this=this@entry=0x557c2f0ab870, mask=mask@entry=0, region=..., data=...) at ./libkwineffects/kwineffects.cpp:574
#37 0x00007f83b26e029a in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=mask@entry=0, region=..., data=...) at ./effects.cpp:426
#38 0x00007f83b011c09f in KWin::Effect::paintScreen (this=this@entry=0x557c2f0d7e70, mask=mask@entry=0, region=..., data=...) at ./libkwineffects/kwineffects.cpp:574
#39 0x00007f83b26e029a in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=mask@entry=0, region=..., data=...) at ./effects.cpp:426
#40 0x00007f83b011c09f in KWin::Effect::paintScreen (this=this@entry=0x557c2f0eb260, mask=mask@entry=0, region=..., data=...) at ./libkwineffects/kwineffects.cpp:574
#41 0x00007f83b26e029a in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=mask@entry=0, region=..., data=...) at ./effects.cpp:426
#42 0x00007f83b011c09f in KWin::Effect::paintScreen (this=this@entry=0x557c2f165950, mask=mask@entry=0, region=..., data=...) at ./libkwineffects/kwineffects.cpp:574
#43 0x00007f83b26e029a in KWin::EffectsHandlerImpl::paintScreen (this=0x557c2f0ab940, mask=0, region=..., data=...) at ./effects.cpp:426
#44 0x00007f83b26b6c9d in KWin::Scene::paintScreen (this=this@entry=0x557c2ee56590, mask=mask@entry=0x7ffe076af660, damage=..., repaint=..., updateRegion=updateRegion@entry=0x7ffe076af630, validRegion=validRegion@entry=0x7ffe076af640, projection=...) at ./scene.cpp:151
#45 0x00007f83b26cec06 in KWin::SceneOpenGL::paint (this=0x557c2ee56590, damage=..., toplevels=...) at ./scene_opengl.cpp:731
#46 0x00007f83b26a981a in KWin::Compositor::performCompositing (this=0x557c2edf2330) at ./composite.cpp:720
#47 0x00007f83b0978653 in QObject::event (this=0x557c2edf2330, e=<optimized out>) at kernel/qobject.cpp:1278
#48 0x00007f83b12858ac in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x557c2edf2330, e=0x7ffe076afab0) at kernel/qapplication.cpp:3804
#49 0x00007f83b128ad4f in QApplication::notify (this=0x7ffe076afd20, receiver=0x557c2edf2330, e=0x7ffe076afab0) at kernel/qapplication.cpp:3561
#50 0x00007f83b094a3b0 in QCoreApplication::notifyInternal2 (receiver=0x557c2edf2330, event=event@entry=0x7ffe076afab0) at kernel/qcoreapplication.cpp:1015
#51 0x00007f83b099f3ae in QCoreApplication::sendEvent (event=0x7ffe076afab0, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:225
#52 QTimerInfoList::activateTimers (this=0x557c2ed6f088) at kernel/qtimerinfo_unix.cpp:637
#53 0x00007f83b099d140 in QEventDispatcherUNIX::activateTimers (this=this@entry=0x557c2ed6b820) at kernel/qeventdispatcher_unix.cpp:549
#54 0x00007f83b099dc3b in QEventDispatcherUNIX::processEvents (this=0x557c2ed6b820, flags=...) at kernel/qeventdispatcher_unix.cpp:611
#55 0x00007f839c1d694d in QUnixEventDispatcherQPA::processEvents (this=<optimized out>, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#56 0x00007f83b09480fa in QEventLoop::exec (this=this@entry=0x7ffe076afc10, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#57 0x00007f83b095090c in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1285
#58 0x00007f83b0c94a7c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1602
#59 0x00007f83b12828e5 in QApplication::exec () at kernel/qapplication.cpp:2979
#60 0x00007f83b2dec206 in kdemain (argc=<optimized out>, argv=0x7ffe076afea8) at ./main_x11.cpp:466
#61 0x00007f83b2a3c3f1 in __libc_start_main (main=0x557c2ea237e0 <main>, argc=3, argv=0x7ffe076afea8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe076afe98) at ../csu/libc-start.c:291
#62 0x0000557c2ea2381a in _start ()

Possible duplicates by query: bug 372305, bug 356620.

Reported using DrKonqi