slub: Add check for kfree() of non slab objects.

We can detect kfree()s on non slab objects by checking for PageCompound().
Works in the same way as for ksize. This helped me catch an invalid
kfree().

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

diff --git a/mm/slub.c b/mm/slub.c
index 5f6e2c4..b3f2e71 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2766,6 +2766,7 @@ void kfree(const void *x)
 
        page = virt_to_head_page(x);
        if (unlikely(!PageSlab(page))) {
+               BUG_ON(!PageCompound(page));
                put_page(page);
                return;
        }