linux-kernel - Re: [PATCH v2 2/3] mm: remain migratetype in freed page

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Date:	Fri, 7 Sep 2012 09:08:27 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.de>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Xishi Qiu <qiuxishi@...wei.com>,
	Wen Congyang <wency@...fujitsu.com>
Subject: Re: [PATCH v2 2/3] mm: remain migratetype in freed page

On Thu, Sep 06, 2012 at 03:13:08PM +0900, Kamezawa Hiroyuki wrote:
> (2012/09/06 14:16), Minchan Kim wrote:
> > The page allocator caches the pageblock information in page->private while
> > it is in the PCP freelists but this is overwritten with the order of the
> > page when freed to the buddy allocator. This patch stores the migratetype
> > of the page in the page->index field so that it is available at all times
> > when the page remain in free_list.
> > 
> sounds reasonable.
> 
> > This patch adds a new call site in __free_pages_ok so it might be
> > overhead a bit but it's for high order allocation.
> > So I believe damage isn't hurt.
> > 
> > * from v1
> >    * Fix move_freepages's migratetype - Mel
> >    * Add more kind explanation in description - Mel
> > 
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> 
> Hmm, page->index is valid only when the page is the head of buddy chunk ?

Yes.

> 
> Anyway,
> 
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Thanks, Kame!

-- 
Kind regards,
Minchan Kim
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