From 44ab57a06ded284db6ccdefc6b76eddb1c34d7ed Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Mon, 9 Aug 2010 17:19:10 -0700 Subject: rmap: add anon_vma bug checks Verify the refcounting doesn't go wrong, and resurrect the check in __page_check_anon_rmap as in old anon-vma code. Signed-off-by: Andrea Arcangeli Signed-off-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/rmap.c b/mm/rmap.c index 2f855babfd0..4d152a6d3a8 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -811,6 +811,7 @@ static void __page_check_anon_rmap(struct page *page, * are initially only visible via the pagetables, and the pte is locked * over the call to page_add_new_anon_rmap. */ + BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); BUG_ON(page->index != linear_page_index(vma, address)); #endif } @@ -1408,6 +1409,7 @@ int try_to_munlock(struct page *page) */ void drop_anon_vma(struct anon_vma *anon_vma) { + BUG_ON(atomic_read(&anon_vma->external_refcount) <= 0); if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) { struct anon_vma *root = anon_vma->root; int empty = list_empty(&anon_vma->head); @@ -1419,6 +1421,7 @@ void drop_anon_vma(struct anon_vma *anon_vma) * the refcount on the root and check if we need to free it. */ if (empty && anon_vma != root) { + BUG_ON(atomic_read(&root->external_refcount) <= 0); last_root_user = atomic_dec_and_test(&root->external_refcount); root_empty = list_empty(&root->head); } -- cgit v1.2.3-18-g5258