"Hangcheck timer elapsed... GPU hung" in 3.8.0-rc2

I got a crash after a few minutes of running 3.8.0-rc2, was able to switch to a vt and look at dmesg:

[ 490.962545] [drm:i915_hangcheck_hung] *ERROR* Hangcheck timer elapsed... GPU hung [ 490.963019] [drm] capturing error event; look for more information in /debug/dri/0/i915_error_state [ 492.961446] [drm:i915_hangcheck_hung] *ERROR* Hangcheck timer elapsed... GPU hung [ 492.965613] [drm:i915_reset] *ERROR* GPU hanging too fast, declaring wedged! [ 492.965621] [drm:i915_reset] *ERROR* Failed to reset chip.

Previously I was on 3.6.10-2.fc17.x86_64, which didn't have any such problem.

dmesg, config, and i915_error_state available from:

http://fieldses.org/~bfields/3.8-hang/

--b.