[PATCH -mm 6/6] add anon_vma bug checks
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From: Rik van Riel on 21 Jun 2010 16:50 From: Andrea Arcangeli <aarcange(a)redhat.com> Subject: 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 <aarcange(a)redhat.com> Signed-off-by: Rik van Riel <riel(a)redhat.com> --- diff --git a/mm/rmap.c b/mm/rmap.c --- a/mm/rmap.c +++ b/mm/rmap.c @@ -815,6 +815,7 @@ static void __page_check_anon_rmap(struc * 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 } @@ -1405,6 +1406,7 @@ 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); @@ -1416,6 +1418,7 @@ void drop_anon_vma(struct anon_vma *anon * 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |