linux-kernel - Re: [PATCH 2/3] mm: Consolidate vma destruction into remove

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Message-ID: <AANLkTin4DKGhcZ4=os1-NxrQ65pEDZ+USG1xpW54y4_T@mail.gmail.com>
Date:	Mon, 27 Sep 2010 09:37:56 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hugh@...itas.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 2/3] mm: Consolidate vma destruction into remove_vma.

Hi Eric,

On Sun, Sep 26, 2010 at 2:34 AM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
> Consolidate vma destruction in remove_vma.   This is slightly
> better for code size and for code maintenance.  Avoiding the pain
> of 3 copies of everything needed to tear down a vma.
>
> Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
> ---
>  mm/mmap.c |   21 +++++----------------
>  1 files changed, 5 insertions(+), 16 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 6128dc8..17dd003 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -643,16 +643,10 @@ again:                    remove_next = 1 + (end > next->vm_end);
>                spin_unlock(&mapping->i_mmap_lock);
>
>        if (remove_next) {
> -               if (file) {
> -                       fput(file);
> -                       if (next->vm_flags & VM_EXECUTABLE)
> -                               removed_exe_file_vma(mm);
> -               }
>                if (next->anon_vma)
>                        anon_vma_merge(vma, next);
> +               remove_vma(next);

remove_vma() does vma->vm_ops->close() but we don't do that here. Are
you sure the conversion is safe?

>                mm->map_count--;
> -               mpol_put(vma_policy(next));
> -               kmem_cache_free(vm_area_cachep, next);
>                /*
>                 * In mprotect's case 6 (see comments on vma_merge),
>                 * we must remove another next too. It would clutter
--
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