linux-kernel - Re: [RFC][PATCH] don't show pgoff of vma if vma is pure ANON (was Re: mmotm 2009-01-12-16-53 uploaded)

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Message-Id: <20090403092743.079f035b.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 3 Apr 2009 09:27:43 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	hugh@...itas.com, mikew@...gle.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, yinghan@...gle.com
Subject: Re: [RFC][PATCH] don't show pgoff of vma if vma is pure ANON (was
 Re: mmotm 2009-01-12-16-53 uploaded)

On Thu, 2 Apr 2009 13:18:16 -0700
Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Thu, 15 Jan 2009 11:43:12 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
> 
> > On Wed, 14 Jan 2009 14:08:35 +0000 (GMT)
> > Hugh Dickins <hugh@...itas.com> wrote:
> > 
> > > On Wed, 14 Jan 2009, KAMEZAWA Hiroyuki wrote:
> > > > Hmm, is this brutal ?
> > > > 
> > > > ==
> > > > Recently, it's argued that what proc/pid/maps shows is ugly when a
> > > > 32bit binary runs on 64bit host.
> > > > 
> > > > /proc/pid/maps outputs vma's pgoff member but vma->pgoff is of no use
> > > > information is the vma is for ANON.
> > > > By this patch, /proc/pid/maps shows just 0 if no file backing store.
> > > > 
> > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> > > > ---
> > > 
> > > Brutal, but sensible enough: revert to how things looked before
> > > we ever starting putting vm_pgoff to work on anonymous areas.
> > > 
> > > I slightly regret losing that visible clue to whether an anonymous
> > > vma has ever been mremap moved.  But have I ever actually used that
> > > info?  No, never.
> > > 
> > > I presume you test !vma->vm_file so the lines fit in, fair enough.
> > > But I think you'll find checkpatch.pl protests at "(!vma->vm_file)?"
> > > 
> > > I dislike its decisions on the punctuation of the ternary operator
> > > - perhaps even more than Andrew dislikes the operator itself!
> > > Do we write a space before a question mark? no: nor before a colon;
> > > but I also dislike getting into checkpatch.pl arguments!
> > > 
> > > While you're there, I'd also be inclined to make task_nommu.c
> > > use the same loff_t cast as task_mmu.c is using.
> > > 
> > Ok, I'll try to update to reasonable style.
> > 
> 
> afaik this update never happened?
> 
Ouch, sorry..could you wait ? I'll do soon....

-Kame

> Here's what I have at present:
> 
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> 
> Recently, it's argued that what proc/pid/maps shows is ugly when a 32bit
> binary runs on 64bit host.
> 
> /proc/pid/maps outputs vma's pgoff member but vma->pgoff is of no use
> information is the vma is for ANON.  With this patch, /proc/pid/maps shows
> just 0 if no file backing store.
> 
> [akpm@...ux-foundation.org: coding-style fixes]
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> Cc: Mike Waychison <mikew@...gle.com>
> Reported-by: Ying Han <yinghan@...gle.com>
> Cc: Hugh Dickins <hugh@...itas.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  fs/proc/task_mmu.c   |    3 ++-
>  fs/proc/task_nommu.c |    3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff -puN fs/proc/task_mmu.c~proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas fs/proc/task_mmu.c
> --- a/fs/proc/task_mmu.c~proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas
> +++ a/fs/proc/task_mmu.c
> @@ -220,7 +220,8 @@ static void show_map_vma(struct seq_file
>  			flags & VM_WRITE ? 'w' : '-',
>  			flags & VM_EXEC ? 'x' : '-',
>  			flags & VM_MAYSHARE ? 's' : 'p',
> -			((loff_t)vma->vm_pgoff) << PAGE_SHIFT,
> +			(!vma->vm_file) ? 0 :
> +				((loff_t)vma->vm_pgoff) << PAGE_SHIFT,
>  			MAJOR(dev), MINOR(dev), ino, &len);
>  
>  	/*
> diff -puN fs/proc/task_nommu.c~proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas fs/proc/task_nommu.c
> --- a/fs/proc/task_nommu.c~proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas
> +++ a/fs/proc/task_nommu.c
> @@ -143,7 +143,8 @@ static int nommu_vma_show(struct seq_fil
>  		   flags & VM_WRITE ? 'w' : '-',
>  		   flags & VM_EXEC ? 'x' : '-',
>  		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
> -		   (unsigned long long) vma->vm_pgoff << PAGE_SHIFT,
> +		   (!vma->vm_file) ? 0 :
> +			(unsigned long long) vma->vm_pgoff << PAGE_SHIFT,
>  		   MAJOR(dev), MINOR(dev), ino, &len);
>  
>  	if (file) {
> _
> 
> --
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