linux-kernel - Re: [PATCH 2/2, v2] mm/migration: Make rmap_walk_anon() and try_to_unmap

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Date:	Tue, 4 Dec 2012 06:42:19 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Turner <pjt@...gle.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Christoph Lameter <cl@...ux.com>, Mel Gorman <mgorman@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH 2/2, v2] mm/migration: Make rmap_walk_anon() and
 try_to_unmap_anon() more scalable

On Sun, Dec 2, 2012 at 7:12 AM, Ingo Molnar <mingo@...nel.org> wrote:
> * Rik van Riel <riel@...hat.com> wrote:
>
>> >+static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
>> >+{
>> >+    down_read(&anon_vma->root->rwsem);
>> >+}
>>
>> I see you did not rename anon_vma_lock and anon_vma_unlock to
>> anon_vma_lock_write and anon_vma_unlock_write.
>>
>> That could get confusing to people touching that code in the
>> future.
>
> Agreed, doing that rename makes perfect sense - I've done that
> in the v2 version attached below.
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index f3f41d2..c20635c 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -118,7 +118,7 @@ static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
>                 up_write(&anon_vma->root->rwsem);
>  }

Note that you haven't changed the names for vma_lock_anon_vma() and
vma_unlock_anon_vma().
I don't have any real good names to suggest though.

> -static inline void anon_vma_lock(struct anon_vma *anon_vma)
> +static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
>  {
>         down_write(&anon_vma->root->rwsem);
>  }
> @@ -128,6 +128,17 @@ static inline void anon_vma_unlock(struct anon_vma *anon_vma)
>         up_write(&anon_vma->root->rwsem);
>  }

And as Rik noticed, you forgot to rename anon_vma_unlock() too.

But really, this is nitpicking. I like the idea behind the patch, and
after giving it a close look, I couldn't find anything wrong with it.

Reviewed-by: Michel Lespinasse <walken@...gle.com>

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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