add missing cache_from_obj !PageSlab check

Taken from PaX.

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/slab.h b/mm/slab.h
index 88c3b15ed..da8768c8a 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -220,6 +220,7 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
 		return s;
 
 	page = virt_to_head_page(x);
+	BUG_ON(!PageSlab(page));
 	cachep = page->slab_cache;
 	if (slab_equal_or_root(cachep, s))
 		return cachep;