mm: simplify anon_vma refcounts
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Tue, 22 Mar 2011 23:32:49 +0000 (16:32 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 23 Mar 2011 00:44:03 +0000 (17:44 -0700)
commit01d8b20dec5f4019283e244aba50ba86fe6ead6e
tree738a2e675547de61f74d6f4019dd5830c40446dd
parent83813267c699ab11cc65a6d9d0f42db42f0862b3
mm: simplify anon_vma refcounts

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>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/rmap.h
mm/rmap.c