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 5f6e2c4a2ba7cbf51e85961eaa56b9d3f82981f0..b3f2e713cdf13d0b17509ed83eadf1117d107637 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;
        }