Comment 25 for bug 761065

Using the latest 2.6.38 kernel from Natty stable this message popped up in dmesg a few times every hour (my system always coming to a complete halt for 1-2 seconds), and after a few hours my system eventually freezed (this is a Lenovo X220 with Sandy Bridge). Setting the semaphore parameter to "1" as suggested above helped somewhat, but I still get the hangcheck errors and freezes.

Installing 2.6.39-0.5~20110427 from kernel-ppa improved on the situation, but eventually after a bit more than a day my system froze again with the following message in dmesg:

May 30 08:02:31 x220 kernel: [26264.491209] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck
 timer elapsed... GPU hung
May 30 08:02:31 x220 kernel: [26264.491229] [drm:kick_ring] *ERROR* Kicking stuck semaphor
e on blt ring
May 30 08:02:32 x220 kernel: [26265.987805] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck
 timer elapsed... GPU hung
May 30 08:02:32 x220 kernel: [26265.987828] [drm:kick_ring] *ERROR* Kicking stuck semaphor
e on blt ring
May 30 08:02:34 x220 kernel: [26267.484409] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck
 timer elapsed... GPU hung
May 30 08:02:34 x220 kernel: [26267.484428] [drm:kick_ring] *ERROR* Kicking stuck semaphor
e on blt ring
May 30 08:02:35 x220 kernel: [26268.981019] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck
 timer elapsed... GPU hung
May 30 08:02:35 x220 kernel: [26268.981039] [drm:kick_ring] *ERROR* Kicking stuck semaphor
e on blt ring
May 30 08:02:37 x220 kernel: [26270.477625] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck
 timer elapsed...May 30 08:04:43 x220 kernel: imklog 4.6.4, log source = /proc/kmsg starte
d.

Semaphore is set to "1" by default on 2.6.39, although it seems from the kernel git log that this change has been reverted since. Now I'm testing 2.6.39 with semaphore set to "0" to see if it eliminates the problem.