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| author | Andrea Arcangeli <aarcange@redhat.com> | 2010-08-09 17:19:10 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-09 20:44:59 -0700 |
| commit | 44ab57a06ded284db6ccdefc6b76eddb1c34d7ed (patch) | |
| tree | e757c1af6be102b90d8a989d6fcfacad93ff6b69 /mm/rmap.c | |
| parent | 21d0d443cdc1658a8c1484fdcece4803f0f96d0e (diff) | |
| download | lwn-44ab57a06ded284db6ccdefc6b76eddb1c34d7ed.tar.gz lwn-44ab57a06ded284db6ccdefc6b76eddb1c34d7ed.zip | |
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 <aarcange@redhat.com>
Signed-off-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>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 2f855babfd06..4d152a6d3a89 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); } |