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Date: Wed, 24 Jul 2013 23:18:56 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
Subject: Re: [PATCH] mm: Save soft-dirty bits on swapped pages
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To: Pavel Emelyanov <xemul@parallels.com>
Cc: Andy Lutomirski <luto@amacapital.net>, James Bottomley <James.Bottomley@hansenpartnership.com>, Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Matt Mackall <mpm@selenic.com>, Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>, Marcelo Tosatti <mtosatti@redhat.com>, KOSAKI Motohiro <kosaki.motohiro@gmail.com>, Stephen Rothwell <sfr@canb.auug.org.au>

On Wed, Jul 24, 2013 at 11:04:53PM +0400, Cyrill Gorcunov wrote:
> On Wed, Jul 24, 2013 at 10:55:41PM +0400, Pavel Emelyanov wrote:
> > > 
> > > Well, some part of information already lays in pte (such as 'file' bit,
> > > swap entries) so it looks natural i think to work on this level. but
> > > letme think if use page struct for that be more convenient...
> > 
> > It hardly will be. Consider we have a page shared between two tasks,
> > then first one "touches" it and soft-dirty is put onto his PTE and,
> > subsequently, the page itself. The we go and clear sofr-dirty for the
> > 2nd task. What should we do with the soft-dirty bit on the page?
> 
> Indeed, this won't help. Well then, bippidy-boppidy-boo, our
> pants are metaphorically on fire (c)

(i meant page flags wont help)

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