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Date: Tue, 11 May 2010 16:11:42 +0100 From: Mel Gorman <mel@....ul.ie> To: Christoph Lameter <cl@...ux.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Minchan Kim <minchan.kim@...il.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Andrea Arcangeli <aarcange@...hat.com>, Rik van Riel <riel@...hat.com> Subject: Re: [PATCH 2/2] mm,migration: Avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks On Tue, May 11, 2010 at 08:59:12AM -0500, Christoph Lameter wrote: > On Mon, 10 May 2010, Mel Gorman wrote: > > > > A simple way to disallow migration of pages is to increment the refcount > > > of a page. > > I guess it could be done by walking the page-tables in advance of the move > > and elevating the page count of any pages faulted and then finding those > > pages afterwards. The fail path would be a bit of a pain though if the page > > tables are partially moved though. It's unnecessarily complicated when the > > temporary stack can be easily avoided. > > Faulting during exec? Copying in arguments and the like > Dont we hold mmap_sem for write? A get_user_pages() > or so on the range will increment the refcount. > Or just identify the temporary stack from the migration side instead of adding to the cost of exec? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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