PS3: Fix memory hotplug

[David Miller]

From: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Date: Wed, 14 May 2008 23:51:29 -0700

> 
> > Paul, any thoughts here ? Should we add a lock ? That would mean being
> > careful as the LMB stuff can be called very early, and spinlock wants
> > things like PACA and possibly lockdep to be around.. 
> 
> Actually, we call early_init_devtree(), which populates the LMB, after
> we initialize the PACA and lockdep, so it -should- be safe to add a
> spinlock.
> 
> Dave ? Any objection to adding a spinlock to the LMB code ?

No objections, just don't add any bugs. :-)