linux-kernel - Re: [PATCH 06/24] HWPOISON: abort on failed unmap

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Message-ID: <20091202134415.GJ18989@one.firstfloor.org>
Date:	Wed, 2 Dec 2009 14:44:15 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 06/24] HWPOISON: abort on failed unmap

On Wed, Dec 02, 2009 at 09:28:19PM +0800, Wu Fengguang wrote:
> On Wed, Dec 02, 2009 at 09:11:50PM +0800, Andi Kleen wrote:
> > >  	 * Now take care of user space mappings.
> > > +	 * Abort on fail: __remove_from_page_cache() assumes unmapped page.
> > >  	 */
> > > -	hwpoison_user_mappings(p, pfn, trapno);
> > > +	if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) {
> > > +		res = -EBUSY;
> > > +		goto out;
> > 
> > It would be good to print something in this case.
> 
> OK.

I'll add it.

> 
> > Did you actually see it during testing?
> 
> Perhaps not.
> 
> > Or maybe loop forever in the unmapper.
> 
> !SWAP_SUCCESS should be rare, so not necessary to loop forever?

I think the loop I originally added was overcautious and could
be even removed possibly now. It probably needs some more analysis how l
ikely unmapping failures really are.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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