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Date: Mon, 1 Mar 2010 10:59:32 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Lameter <cl@linux-foundation.org>,
       David Rientjes <rientjes@google.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>, Nick Piggin <npiggin@suse.de>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org, haicheng.li@intel.com
Subject: Re: [PATCH] [4/4] SLAB: Fix node add timer race in cache_reap
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On Fri, 26 Feb 2010 18:31:15 +0100
Andi Kleen <andi@firstfloor.org> wrote:

> On Fri, Feb 26, 2010 at 11:24:50AM -0600, Christoph Lameter wrote:
> > On Fri, 26 Feb 2010, Andi Kleen wrote:
> > 
> > > > > Memory hotplug with node add never quite worked on x86 before,
> > > > > for various reasons not related to slab.
> > > >
> > > > Ok but why did things break in such a big way?
> > >
> > > 1) numa memory hotadd never worked
> > 
> > Well Kamesan indicated that this worked if a cpu became online.
> 
> I mean in the general case. There were tons of problems all over.
> 
Then, it's cpu hotplug matter, not memory hotplug.
cpu hotplug callback should prepaare 


	l3 = searchp->nodelists[node];
	BUG_ON(!l3);

before onlined. Rather than taking care of races.


Thanks,
-Kame

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