I'm using KDE Plasma 5 desktop with compositing enabled (Rendering backend OpenGL 3.1, EGL OpenGL interface). Sometimes (~ once an hour) whole Xorg freezes when switching windows via alt+tab. This appears in the dmesg: [ 703.460565] [drm] stuck on render ring [ 703.461616] [drm] GPU HANG: ecode 0:0x00200000, in Xorg.bin [1414], reason: Ring hung, action: reset [ 703.461619] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace. [ 703.461621] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel [ 703.461622] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue. [ 703.461623] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it. [ 703.461625] [drm] GPU crash dump saved to /sys/class/drm/card0/error Dump of /sys/class/drm/card0/error is here: https://rnovacek.fedorapeople.org/grfx-crash.log I'm using Fedora 21 with following packages: xorg-x11-server-Xorg-1.16.2.901-1.fc21.x86_64 xorg-x11-drv-intel-2.99.916-3.20141117.fc21.x86_64 mesa-dri-drivers-10.4.2-1.20150112.fc21.x86_64 Let me know if I can provide some additional information.
The batchbuffer is completely overwritten with pixel data. Can you please try with i915.enable_ppgtt=2 on the kernel commandline? The bug should still happen eventually but it will help narrow down the culprit.
I've enabled that option, but the bug didn't appeared since that. It might get fixed by some update in the meantime. Closing it now.
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