Bug#637958: X.org crash leaves GPU in an inconsistent state and renders system unbootable

[Martin <mjb@cs.bath.ac.uk>]

On Thu, 2011-08-25 at 11:08 +0200, Michel Dänzer wrote:
> On Don, 2011-08-25 at 09:50 +0100, Martin wrote: 
> > On Wed, 2011-08-24 at 08:50 +0200, Michel Dänzer wrote:
> > > On Die, 2011-08-23 at 23:14 +0100, Martin wrote: 
> > > > 
> > > > Right; have upgraded to the latest X.org and kernel in backports and the
> > > > problem still persists.  Something causes the machine to hang while
> > > > bieng used interactively in X and after this loading the kernel psmouse
> > > > module hangs the machine.
> > > > 
> > > > What should I try next?
> > > 
> > > Can you try if the hangs in X happen when the psmouse module is never
> > > loaded in the first place?
> > 
> > So I've tried the following:
> > 
> > 1. Boot from a Debian 4.0 install CD to clear the non-volatile fault.
> > 
> > 2. Boot from a Debian 6.0 install CD to blacklist psmouse without
> > loading it.
> > 
> > 3. Reboot the system and let X start.
> > 
> > 4. Log in via SSH and run four separate loops, each of which starts a
> > set of programs, sleeps for a prime amount of time, kills them and sleep
> > for another prime amount of time.  One loop ran five xterms, one ran two
> > glxgears (one fullscreen) and one ran twenty xeyes while the final loop
> > ran a fulscreen mplayer.  When I have run this kind of load
> > interactively it hangs the machine within 20-30 minutes, run via SSH it
> > ran stably for over 12 hours.
> > 
> > Thus I conclude that the thing that triggers the bug is dependent on
> > psmouse or (inclusive-or) interactive use of the machine via keyboard
> > and mouse.
> 
> It's important to make the distinction between these possibilities
> though:
> 
> Can you still trigger the hang moving the mouse interactively (e.g. with
> a USB mouse) when psmouse was never loaded?

With no psmouse module and a USB mouse I can still trigger the fault,
althought it takes longer, i.e. 20 minutes to 1/2 hour.

> If yes, does Option "SWcursor" in xorg.conf work around the problem?
> (Verify in Xorg.0.log that the option takes effect)

I've set this and so far it seems to have helped.  I used the machine
interactively for 20 minutes or so and left it running loops starting
programs overnight.  I should hopefully have more time to use it over
the next few days and will report back.

Cheers,
 - Martin