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Date: Wed, 10 Oct 2007 10:39:32 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Akinobu Mita <akinobu.mita@gmail.com>
cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH -mm] slub: fix cpu hotplug offline/online path
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On Wed, 10 Oct 2007, Akinobu Mita wrote:

> I couldn't use get_cpu_slab() for that check. But I reviced the patch to do
> what you said.

Why would get_cpu_slab not work?

> +	if (per_cpu(kmem_cache_cpu_free, cpu)) {
> +		/* Already initialized once */
> +		return;
> +	}
> +

kmem_cache_cpu_free is not only NULL if the cpu is not up yet but it is 
also NULL if the per cpu pool of kmem_cache_cpu structures was 
exhausted.