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

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Message-ID: <AANLkTinrhzKSTwzLCsHmGXr5Q5kfi=j0Zvh0rsmsAJ4m@mail.gmail.com>
Date:	Mon, 27 Sep 2010 10:11:20 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH 2/3] mm: Consolidate vma destruction into remove_vma.

On Mon, Sep 27, 2010 at 9:37 AM, Pekka Enberg <penberg@...nel.org> wrote:
>>> 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?
>
> Definitely.  It actually isn't possible to reach that point with a
> vma that has a close method.
>
> Until I had traced through all of the code paths I suspect calling
> remove_vma there might have been a bug fix.

Can we amend that to the changelog, please? Otherwise

Acked-by: Pekka Enberg <penberg@...nel.org>

                        Pekka
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