Created attachment 115653 [details]
dmesg output

While playing L4D2 today I got a lot of GPU lockups.

While the lockups seem to happen randomly, they are fairly easy to reproduce in
the third chapter (The Mall) of the Dead Center campaign. I recorded an
apitrace while encountering 3 lockups and there seem to be at least a couple of
lockups each time I retrace it:

 http://constexpr.org/tmp/L4D2-radeonsi.trace.xz (507 MiB)

At least driver was able to successfully reset the GPU each time.

There also seem to be some infrequent rendering glitches.

Probably related to bug 89228, and possibly bug 90217, bug 90284 and/or bug
89954 (all reports of lockups with Source engine games).

GPU; Radeon HD 7950 (TAHITI)
Mesa 10.6.0-devel (git-3bdbc1e)
LLVM r236436
Linux 4.0.1-gentoo

The above logs and apitrace were recorded with unsafe-fp-math enbled (see bug
89069 comment 34) but the lockups also happen without it. I also noticed some
VM fault messages in dmesg while running L4D2 without unsafe-fp-math.