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Date: Wed, 4 Sep 2013 17:25:05 +0900
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/16] slab: overload struct slab over struct page to
 reduce memory usage
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On Wed, Sep 04, 2013 at 11:38:04AM +0800, Wanpeng Li wrote:
> Hi Joonsoo,
> On Fri, Aug 23, 2013 at 03:35:39PM +0900, Joonsoo Kim wrote:
> >On Thu, Aug 22, 2013 at 04:47:25PM +0000, Christoph Lameter wrote:
> >> On Thu, 22 Aug 2013, Joonsoo Kim wrote:
> >
> [...]
> >struct slab's free = END
> >kmem_bufctl_t array: ACTIVE ACTIVE ACTIVE ACTIVE ACTIVE
> ><we get object at index 0>
> >
> 
> Is there a real item for END in kmem_bufctl_t array as you mentioned above?
> I think the kmem_bufctl_t array doesn't include that and the last step is 
> not present. 

Yes, there is. BUFCTL_END is what I told for END. A slab is initialized in
cache_init_objs() and a last step in that function is to set last entry of
a free array of a slab to BUFCTL_END. This value remains in the whole life
cycle of a slab.

Thanks.
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