Date: Tue, 19 Jun 2007 12:22:33 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
To: Mel Gorman <mel@skynet.ie>
cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
       kamezawa.hiroyu@jp.fujitsu.com
Subject: Re: [PATCH 0/7] Memory Compaction v2
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 <Pine.LNX.4.64.0706181022530.4751@schroedinger.engr.sgi.com>
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On Tue, 19 Jun 2007, Mel Gorman wrote:

> Agreed. When I put this together first, I felt I would be able to isolate
> pages of different types on migratelist but that is not the case as migration
> would not be able to tell the difference between a LRU page and a pagetable
> page. I'll rename cc->migratelist to cc->migratelist_lru with the view to
> potentially adding cc->migratelist_pagetable or cc->migratelist_slab later.

Right. The particular issue with moving page table pages or slab pages is 
that you do not have a LRU. The page state needs to be established in a 
different way and there needs to be mechanism to ensure that the page is 
not currently being setup or torn down. For the slab pages I have relied 
on page->inuse > 0 to signify a page in use. I am not sure how one would 
realize that for page table pages.

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