(In reply to J0k3r from comment #10)
> https://bugs.freedesktop.org/show_bug.cgi?id=89203 is probably a duplicate
> of this bug.
> 
> I tested it with linux 3.19 and different (git~51b43c5, 10.4.6, 10.3.5) mesa
> versions, but they don't seem to make a difference. So, no,
> a338dc01866ce50bf7555ee8dc08491c7f63b585 does not help. Even with mesa
> 10.3.5, where some people reported this was the the last working version for
> them, the hangs occured. So it's probably related to some kernel issue, too.

You might be seeing:
https://bugzilla.kernel.org/show_bug.cgi?id=90741