From 012f18004da33ba672e3c60838cc4898126174d3 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Mon, 9 Aug 2010 17:18:40 -0700 Subject: mm: always lock the root (oldest) anon_vma Always (and only) lock the root (oldest) anon_vma whenever we do something in an anon_vma. The recently introduced anon_vma scalability is due to the rmap code scanning only the VMAs that need to be scanned. Many common operations still took the anon_vma lock on the root anon_vma, so always taking that lock is not expected to introduce any scalability issues. However, always taking the same lock does mean we only need to take one lock, which means rmap_walk on pages from any anon_vma in the vma is excluded from occurring during an munmap, expand_stack or other operation that needs to exclude rmap_walk and similar functions. Also add the proper locking to vma_adjust. Signed-off-by: Rik van Riel Tested-by: Larry Woodman Acked-by: Larry Woodman Reviewed-by: Minchan Kim Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Mel Gorman Acked-by: Linus Torvalds Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ksm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/ksm.c') diff --git a/mm/ksm.c b/mm/ksm.c index eb9f6806ed51..da6037c261f1 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -325,7 +325,7 @@ static void drop_anon_vma(struct rmap_item *rmap_item) { struct anon_vma *anon_vma = rmap_item->anon_vma; - if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) { + if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) { int empty = list_empty(&anon_vma->head); anon_vma_unlock(anon_vma); if (empty) -- cgit v1.2.3-59-g8ed1b