Jack Steiner wrote:
> Nick -
> 
> The latest 2.6.12-rc5-mm2 tree fails to boot on some of the 64p
> SGI systems. The system hangs immediately after printing:
> 
> 	...
> 	Inode-cache hash table entries: 8388608 (order: 12, 67108864 bytes)
> 	Mount-cache hash table entries: 1024
> 	Boot processor id 0x0/0x0
> 	Brought up 64 CPUs
> 	Total of 64 processors activated (118415.36 BogoMIPS).
> 
> 
> I have isolated the failure to cpu 0 hanging in sched_balance_self() during
> a fork (or clone).  The "while" loop at the end of function never 
> terminates, ie. sd is never NULL.
> 
> Is this a problem that you have seen before. If not, I'll do some
> more digging & isolate the problem.
> 

Hi Jack,
I haven't completely got to the bottom of this yet, but I was able
to reproduce on a 64-way Altix, and something like the attached patch
seems to 'fix' the problem.

I didn't have time to find what's gone wrong tonight, but I'll get
to that tomorrow.

-- 
SUSE Labs, Novell Inc.