linux-kernel - Re: [patch 2/3] [PATCH] mm: pagemap -- Inspect _PAGE_SOFT

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Date:	Tue, 08 Oct 2013 10:26:42 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Andy Lutomirski <luto@...capital.net>,
	Matt Mackall <mpm@...enic.com>,
	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Peter Zijlstra <peterz@...radead.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: Re: [patch 2/3] [PATCH] mm: pagemap -- Inspect _PAGE_SOFT_DIRTY only
 on present pages

On Tue, Oct 08, 2013 at 01:00:21PM +0400, Cyrill Gorcunov wrote:
> In case if a page we are inspecting is laying in swap we may
> occasionally report it as having soft dirty bit (even if it
> is clean). pte_soft_dirty helper should be called on present
> pte only.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
> Cc: Pavel Emelyanov <xemul@...allels.com>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Matt Mackall <mpm@...enic.com>
> Cc: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
> Cc: Marcelo Tosatti <mtosatti@...hat.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...il.com>
> Cc: Stephen Rothwell <sfr@...b.auug.org.au>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>

Looks nice to me.

Reviewed-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>

> ---
>  fs/proc/task_mmu.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.git/fs/proc/task_mmu.c
> ===================================================================
> --- linux-2.6.git.orig/fs/proc/task_mmu.c
> +++ linux-2.6.git/fs/proc/task_mmu.c
> @@ -941,6 +941,8 @@ static void pte_to_pagemap_entry(pagemap
>  		frame = pte_pfn(pte);
>  		flags = PM_PRESENT;
>  		page = vm_normal_page(vma, addr, pte);
> +		if (pte_soft_dirty(pte))
> +			flags2 |= __PM_SOFT_DIRTY;
>  	} else if (is_swap_pte(pte)) {
>  		swp_entry_t entry;
>  		if (pte_swp_soft_dirty(pte))
> @@ -960,7 +962,7 @@ static void pte_to_pagemap_entry(pagemap
>  
>  	if (page && !PageAnon(page))
>  		flags |= PM_FILE;
> -	if ((vma->vm_flags & VM_SOFTDIRTY) || pte_soft_dirty(pte))
> +	if ((vma->vm_flags & VM_SOFTDIRTY))
>  		flags2 |= __PM_SOFT_DIRTY;
>  
>  	*pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags);
> 
> --
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