Date: Wed, 17 Feb 2010 01:04:47 +1100
From: Nick Piggin <npiggin@suse.de>
To: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <andi@firstfloor.org>, Pekka Enberg <penberg@cs.helsinki.fi>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org, haicheng.li@intel.com
Subject: Re: [PATCH] [3/4] SLAB: Set up the l3 lists for the memory of
 freshly added memory v2
Message-ID: <20100216140447.GN5723@laptop>
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 <alpine.DEB.2.00.1002111344130.8809@chino.kir.corp.google.com>
 <20100215060655.GH5723@laptop>
 <alpine.DEB.2.00.1002151344020.26927@chino.kir.corp.google.com>
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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.
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