Created attachment 117725 [details]
My desktop froze for a handful of seconds and then I found this text in dmesg:
[179129.531308] [drm] GPU HANG: ecode 6:-1:0x00000000, reason: Kicking stuck semaphore on render ring, action: continue
[179129.531311] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
[179129.531312] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
[179129.531313] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
[179129.531314] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
[179129.531315] [drm] GPU crash dump saved to /sys/class/drm/card0/error
I am running Ubuntu 15.04 with the following kernel:
Linux apol1 4.1.1-040101-generic #201507030635 SMP Fri Jul 3 10:38:27 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
The laptop is connected to a Dell U3011 (2560x1600) through the DisplayPort. See file attached.
*** This bug has been marked as a duplicate of bug 54226 ***