Re: [PATCH] [3/4] SLAB: Set up the l3 lists for the memory of freshly added memory v2

[Nick Piggin <npiggin@suse.de>]

On Mon, Feb 15, 2010 at 01:47:29PM -0800, David Rientjes wrote:
> On Mon, 15 Feb 2010, Nick Piggin wrote:
> 
> > > > @@ -1577,6 +1595,8 @@ void __init kmem_cache_init_late(void)
> > > >  	 */
> > > >  	register_cpu_notifier(&cpucache_notifier);
> > > >  
> > > > +	hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
> > > > +
> > > 
> > > Only needed for CONFIG_NUMA, but there's no side-effects for UMA kernels 
> > > since status_change_nid will always be -1.
> > 
> > Compiler doesn't know that, though.
> > 
> 
> Right, setting up a memory hotplug callback for UMA kernels here isn't 
> necessary although slab_node_prepare() would have to be defined 
> unconditionally.  I made this suggestion in my review of the patchset's 
> initial version but it was left unchanged, so I'd rather see it included 
> than otherwise stall out.  This could always be enclosed in
> #ifdef CONFIG_NUMA later just like the callback in slub does.

It's not such a big burden to annotate critical core code with such
things. Otherwise someone else ends up eventually doing it.