From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pekka Enberg <penberg@kernel.org>
Subject: Re: [PATCH 05/20] mm: Simplify anon_vma refcounts
Date: Sat, 28 Aug 2010 18:13:13 +0300
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References: <20100828141637.421594670@chello.nl>
	<20100828142455.742059699@chello.nl>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>, Avi Kivity <avi@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>, akpm@linux-foundation.org, Linus Torvalds <torvalds@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, David Miller <davem@davemloft.net>, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@suse.de>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Yanmin Zhang <yanmin_zhang@linux.intel.com>, Stephen Rothwell <sfr@canb.auug.org.au>

On Sat, Aug 28, 2010 at 5:16 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> This patch changes the anon_vma refcount to be 0 when the object is
> free. It does this by adding 1 ref to being in use in the anon_vma
> structure (iow. the anon_vma->head list is not empty).
>
> This allows a simpler release scheme without having to check both the
> refcount and the list as well as avoids taking a ref for each entry
> on the list.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

FWIW,

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