linux-kernel - Re: [PATCH] [10/16] HWPOISON: Handle poisoned pages in set_page

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Message-ID: <20090609125139.GE5589@localhost>
Date:	Tue, 9 Jun 2009 20:51:39 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Andi Kleen <andi@...stfloor.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH] [10/16] HWPOISON: Handle poisoned pages in
	set_page_dirty()

On Tue, Jun 09, 2009 at 05:59:20PM +0800, Nick Piggin wrote:
> On Wed, Jun 03, 2009 at 08:46:43PM +0200, Andi Kleen wrote:
> > 
> > Bail out early in set_page_dirty for poisoned pages. We don't want any
> > of the dirty accounting done or file system write back started, because
> > the page will be just thrown away.
> 
> I don't agree with adding overhead to fastpaths like this. Your
> MCE handler should have already taken care of this so I can't
> see what it can gain.

Agreed to remove this patch. The poisoned page should already be
isolated (in normal cases), and won't reach this code path.

Thanks,
Fengguang

> > 
> > Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> > 
> > ---
> >  mm/page-writeback.c |    4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > Index: linux/mm/page-writeback.c
> > ===================================================================
> > --- linux.orig/mm/page-writeback.c	2009-06-03 19:36:20.000000000 +0200
> > +++ linux/mm/page-writeback.c	2009-06-03 19:36:23.000000000 +0200
> > @@ -1304,6 +1304,10 @@
> >  {
> >  	struct address_space *mapping = page_mapping(page);
> >  
> > +	if (unlikely(PageHWPoison(page))) {
> > +		SetPageDirty(page);
> > +		return 0;
> > +	}
> >  	if (likely(mapping)) {
> >  		int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
> >  #ifdef CONFIG_BLOCK
--
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