Created attachment 88305 [details]
Backtrace of hanging kwin_x11

When opening a new window, kwin_x11 freezes completely and doesn't even react on 'SIGTERM' anymore - it needs to be killed using 'SIGKILL' from a VT.

This happens with any application and also with modal windows (connection dialog of Quassel).

I can only reproduce this with compositing enabled.

The following components are up-to-date from git master:
- all of KF5
- all of Plasma5/KWin5
- mesa
- libdrm

xf86-video-intel is at 2.99.914
Kernel is at 3.16.0-rc7

GDB backtrace of hanging kwin_x11 is attached.

kwin supportInformation can be found below.

Version
=======
KWin version: 5.0.1
Qt Version: 5.3.1

Operation Mode: X11 only

Options
=======
focusPolicy: 1
nextFocusPrefersMouse: false
clickRaise: true
autoRaise: false
autoRaiseInterval: 750
delayFocusInterval: 300
shadeHover: false
shadeHoverInterval: 250
separateScreenFocus: false
placement: 4
focusPolicyIsReasonable: true
borderSnapZone: 10
windowSnapZone: 10
centerSnapZone: 0
snapOnlyWhenOverlapping: false
showDesktopIsMinimizeAll: false
rollOverDesktops: true
focusStealingPreventionLevel: 1
legacyFullscreenSupport: false
operationTitlebarDblClick: 
commandActiveTitlebar1: 0
commandActiveTitlebar2: 30
commandActiveTitlebar3: 2
commandInactiveTitlebar1: 4
commandInactiveTitlebar2: 30
commandInactiveTitlebar3: 2
commandWindow1: 7
commandWindow2: 8
commandWindow3: 8
commandWindowWheel: 31
commandAll1: 10
commandAll2: 3
commandAll3: 14
keyCmdAllModKey: 16777250
showGeometryTip: false
condensedTitle: false
electricBorderMaximize: true
electricBorderTiling: true
electricBorderCornerRatio: 0.25
borderlessMaximizedWindows: false
killPingTimeout: 5000
hideUtilityWindowsForInactive: true
inactiveTabsSkipTaskbar: false
autogroupSimilarWindows: false
autogroupInForeground: true
compositingMode: 1
useCompositing: true
compositingInitialized: true
hiddenPreviews: 1
unredirectFullscreen: false
glSmoothScale: 2
colorCorrected: false
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: true
glStrictBindingFollowsDriver: true
glCoreProfile: false
glPreferBufferSwap: 101
glPlatformInterface: 

Screen Edges
============
desktopSwitching: false
desktopSwitchingMovingClients: false
cursorPushBackDistance: 
timeThreshold: 150
reActivateThreshold: 350
actionTopLeft: 0
actionTop: 0
actionTopRight: 0
actionRight: 0
actionBottomRight: 0
actionBottom: 0
actionBottomLeft: 0
actionLeft: 0

Screens
=======
Multi-Head: no
Active screen follows mouse:  yes
Number of Screens: 1
Screen 0 Geometry: 0,0,1920x1080

Decoration
==========
Current Plugin: Oxygen
Shadows: yes
Alpha: yes
Announces Alpha: yes
Tabbing: yes
Frame Overlap: no
Blur Behind: no

Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile 
OpenGL version string: 3.0 Mesa 10.3.0-devel (git-e9a4e74)
OpenGL platform interface: GLX
OpenGL shading language version string: 1.30
Driver: Intel
GPU class: IvyBridge
OpenGL version: 3.0
GLSL version: 1.30
Mesa version: 10.3
X server version: 1.16
Linux kernel version: 3.16
Direct rendering: Requires strict binding: yes
GLSL shaders:  yes
Texture NPOT support:  yes
Virtual Machine:  no
OpenGL 2 Shaders are used
Painting blocks for vertical retrace:  no

Loaded Effects:
---------------
zoom
slidingpopups
kwin4_effect_login
slide
screenshot
minimizeanimation
desktopgrid
kwin4_effect_translucency
kwin4_effect_fade
kwin4_effect_maximize
presentwindows
kwin4_effect_dialogparent
highlightwindow
blur
contrast
logout
dashboard
startupfeedback
screenedge
kscreen

Currently Active Effects:
-------------------------
blur
contrast

Effect Settings:
----------------
zoom:
zoomFactor: 1.2
mousePointer: 0
mouseTracking: 0
enableFocusTracking: false
followFocus: true
focusDelay: 350
moveFactor: 20
targetZoom: 1

slidingpopups:
fadeInTime: 150
fadeOutTime: 250

kwin4_effect_login:

slide:

screenshot:

minimizeanimation:

desktopgrid:
zoomDuration: 300
border: 10
desktopNameAlignment: 0
layoutMode: 0
customLayoutRows: 2
usePresentWindows: true

kwin4_effect_translucency:

kwin4_effect_fade:

kwin4_effect_maximize:

presentwindows:
layoutMode: 0
showCaptions: true
showIcons: true
doNotCloseWindows: false
ignoreMinimized: false
accuracy: 20
fillGaps: true
fadeDuration: 150
showPanel: false
leftButtonWindow: 1
rightButtonWindow: 2
middleButtonWindow: 0
leftButtonDesktop: 2
middleButtonDesktop: 0
rightButtonDesktop: 0

kwin4_effect_dialogparent:

highlightwindow:

blur:
blurRadius: 12
cacheTexture: true

contrast:

logout:
useBlur: true

dashboard:
brightness: 0.5
saturation: 0.5
blur: false

startupfeedback:

screenedge:

kscreen: