Big problems with 7.1 locking up :-(

[Pete French]

> I rather feared as much.  Let's run down the path of "perhaps there's a 
> problem with the new UDP locking code" for a bit and see where it takes us. 
> Is it possible to run those boxes with WITNESS -- I believe that the fact that
> "show alllocks" is failing is because WITNESS isn't present.

Yes, I can do that. The only reason I wasn't running with WITNESS is that
it didn't lock up when I added the BREAK_TO_DEBUGGER so I was seeing if
a simple GENERIC kernel would lock up when I added that. I will go
back and add WITNESS when you tell me theres nothing more
we can get out of this lock up (recompiling will involve restarting the
machine so I loose the 'boekn to debugger' state). Should I add
anything else ? Skip spinlocks ? Invariants ?

> The other thing we can do is revert UDP to using purely write locks -- the
> risk there is that it might change the timing but not actually resolve the
> bug, so if we can analyze it a bit using WITNESS first that would be useful.

Yes, I will run with WITNESS and anything else you might want. Is there
anything else you, or anyone else, wants from this kernel ? It may take
another day to lock up when I've restarted it unfortunately.

-pete.