https://bugzilla.kernel.org/show_bug.cgi?id=42678
--- Comment #2 from Torsten Kaiser just.for.lkml@googlemail.com 2012-01-29 20:31:43 --- For the lockup itself I have filed: https://bugs.freedesktop.org/show_bug.cgi?id=45329
The kernel regression has been partly addressed by: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=...
The mutex deadlock has been fixed, but X still fails to recover from the GPU lockup. With kernel 3.1 or 3.2 I didn't even noticed that these lockups where happening.
See http://marc.info/?l=linux-kernel&m=132739068529857&w=2 for a SysRq+W backtrace of the stuck X process