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

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Message-ID: <20090604125026.GA29026@localhost>
Date:	Thu, 4 Jun 2009 20:50:26 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"npiggin@...e.de" <npiggin@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH] [6/16] HWPOISON: Add various poison checks in
	mm/memory.c

On Thu, Jun 04, 2009 at 08:52:28PM +0800, Andi Kleen wrote:
> 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)

I guess they are handled by do_anonymous_page() or do_wp_page(),
instead of do_linear_fault()/do_nonlinear_fault()?

Thanks,
Fengguang

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