Created attachment 104681 [details]
This happened on a Lenovo X220, using Ubuntu Precise, with LTS-Trusty Kernel (3.13.0-30) and LTS-Saucy Xorg stack:
[312856.300811] [drm] stuck on render ring
[312856.300815] [drm] stuck on blitter ring
[312856.300817] [drm] GPU crash dump saved to /sys/class/drm/card0/error
[312856.300818] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
[312856.300819] [drm] Please file a new bug report on bugs.freedesktop.org against DRI -> DRM/Intel
[312856.300820] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
[312856.300821] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
This is the same hardware and software as in the bug https://bugs.freedesktop.org/show_bug.cgi?id=82665 , which I reported earlier. I don't know the exact circumstances. It happened to one of our users and seems to happen every couple of days.
*** This bug has been marked as a duplicate of bug 54226 ***