Created attachment 78163 [details]
backtrace from gdb and accompanying Xorg bt.
Hardware: lenovo E530c ("Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller")
OS: debian 3.2.0-4-amd64
1) Open libreoffice writer; new document.
2) Make a few new pages (ctl-enter).
3) Scroll up and down rapidly with the touchpad a few times.
4) X freezes, with two outcomes: (a) either a hung GPU and all windows black (but, mouse still moves); or else (b) totally frozen X with "[mi] EQ overflow continuing." and backtrace in Xorg.0.log.
This doesn't occur on a similar lenovo machine (T420i). It doesn't seem to happen in other applications; libreoffice folks determined it to be not their problem ( https://bugs.freedesktop.org/show_bug.cgi?id=62946 ) and suggested the intel drivers.
Logs for case (a) are at http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=10;att=0;bug=703749 and for case (b) are at http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=15;att=0;bug=703749 .
I've also attached a debugger to Xorg, as described here ( http://wiki.x.org/wiki/Development/Documentation/ServerDebugging , although it need ctrl-c to get it to backtrace) -- I'm attaching the backtrace from case (b).
It's a GPU hang. Please attach /sys/kernel/debug/dri/0/i915_error_state.
Created attachment 78188 [details]
hung i915 error state
Sorry; should have said that this was also in one of those links.
Note that the GPU only hangs about half the time; the other half the time the error state is "no error state collected".
Created attachment 78189 [details]
Xorg.0.log that accompanies i915_error_state
The backtrace from Xorg.0.log entered previously occurs when there is no i915_error_state; in the case that there is a i915_error_state, Xorg.0.log looks like this.
Upstream stable reverted the chicken bit removal rather than backport the correct driver code.