Re: [PATCH] [6/16] HWPOISON: Add various poison checks in mm/memory.c

[Andi Kleen]

On Thu, Jun 04, 2009 at 07:55:33PM +0800, Wu Fengguang wrote:
> On Thu, Jun 04, 2009 at 01:19:15PM +0800, Andi Kleen wrote:
> > On Thu, Jun 04, 2009 at 12:26:03PM +0800, Wu Fengguang wrote:
> > > On Thu, Jun 04, 2009 at 02:46:38AM +0800, Andi Kleen wrote:
> > > >
> > > > Bail out early when hardware poisoned pages are found in page fault handling.
> > >
> > > I suspect this patch is also not absolutely necessary: the poisoned
> > > page will normally have been isolated already.
> >
> > It's needed to prevent new pages comming in when there is a parallel
> > fault while the memory failure handling is in process.
> > Otherwise the pages could get remapped in that small window.
> 
> This patch makes no difference at least for file pages, including tmpfs.

I was more thinking of anonymous pages with multiple mappers (e.g.
COW after fork)

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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