From 01d8b20dec5f4019283e244aba50ba86fe6ead6e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 22 Mar 2011 16:32:49 -0700 Subject: 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 Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Hugh Dickins Acked-by: Mel Gorman Acked-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/rmap.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/rmap.h b/include/linux/rmap.h index fd56111a52c..830e65dc01e 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -73,7 +73,13 @@ static inline void get_anon_vma(struct anon_vma *anon_vma) atomic_inc(&anon_vma->refcount); } -void put_anon_vma(struct anon_vma *); +void __put_anon_vma(struct anon_vma *anon_vma); + +static inline void put_anon_vma(struct anon_vma *anon_vma) +{ + if (atomic_dec_and_test(&anon_vma->refcount)) + __put_anon_vma(anon_vma); +} static inline struct anon_vma *page_anon_vma(struct page *page) { @@ -116,7 +122,6 @@ void unlink_anon_vmas(struct vm_area_struct *); int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); void __anon_vma_link(struct vm_area_struct *); -void anon_vma_free(struct anon_vma *); static inline void anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) @@ -125,6 +130,8 @@ static inline void anon_vma_merge(struct vm_area_struct *vma, unlink_anon_vmas(next); } +struct anon_vma *page_get_anon_vma(struct page *page); + /* * rmap interfaces called when adding or removing pte of page */ -- cgit v1.2.3-18-g5258