linux-kernel - Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEs when page tables are being moved after the VMA has already moved

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Message-Id: <20100428093642.ca869815.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 28 Apr 2010 09:36:42 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Mel Gorman <mel@....ul.ie>, Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Christoph Lameter <cl@...ux.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEs when
 page tables are being moved after the VMA has already moved

On Wed, 28 Apr 2010 02:08:33 +0200
Andrea Arcangeli <aarcange@...hat.com> wrote:

> On Wed, Apr 28, 2010 at 09:03:02AM +0900, KAMEZAWA Hiroyuki wrote:
> > I bet calling __get_user_pages_fast() before vma_adjust() is the way to go. 
> > When page_count(page) != page_mapcount(page) +1, migration skip it.
> 
> My proposed fix avoids to walk the pagetables once more time and to
> mangle over the page counts. Can you check it? It works but it needs
> more review.

Sure...but can we avoid temporal objrmap breakage(inconsistency) by it ?

THanks,
-Kame

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