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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Nikanth Karthikesan <knikanth@suse.de>
Subject: Re: [PATCH v2] After swapout/swapin private dirty mappings are reported clean in smaps
Cc: kosaki.motohiro@jp.fujitsu.com, Richard Guenther <rguenther@suse.de>,
        linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        balbir@linux.vnet.ibm.com, Michael Matz <matz@novell.com>,
        Matt Mackall <mpm@selenic.com>, linux-kernel@vger.kernel.org
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Date: Wed, 15 Sep 2010 13:48:11 +0900 (JST)
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> On Wednesday 15 September 2010 05:56:36 KOSAKI Motohiro wrote:
> > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > > index 439fc1f..06fc468 100644
> > > --- a/fs/proc/task_mmu.c
> > > +++ b/fs/proc/task_mmu.c
> > > @@ -368,7 +368,11 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long
> > > addr, unsigned long end, mss->shared_clean += PAGE_SIZE;
> > >  			mss->pss += (PAGE_SIZE << PSS_SHIFT) / mapcount;
> > >  		} else {
> > > -			if (pte_dirty(ptent))
> > > +			/*
> > > +			 * File-backed pages, now anonymous are dirty
> > > +			 * with respect to the file.
> > > +			 */
> > > +			if (pte_dirty(ptent) || (vma->vm_file && PageAnon(page)))
> > >  				mss->private_dirty += PAGE_SIZE;
> > >  			else
> > >  				mss->private_clean += PAGE_SIZE;
> > 
> > This is risky than v1. number of dirties are used a lot of application.
> > 
> 
> This is exactly to help those applications, as currently after swap-out and 
> swap-in, the same pages are accounted as "Private_Clean:" instead of 
> "Private_Dirty:".

I don't think so. incorrect infomation bring a lot of confusion rather than its worth.