mm/slub: Add debugging to verify correct cache use on kmem_cache_free()

Add additional debugging to check that the objects is actually from the cache
the caller claims. Doing so currently trips up some other debugging code. It
takes a lot to infer from that what was happening.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
[ penberg@kernel.org: Use pr_err() ]
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/mm/slub.c b/mm/slub.c
index c67bd0a..9905921 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2614,6 +2614,13 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
 
 	page = virt_to_head_page(x);
 
+	if (kmem_cache_debug(s) && page->slab != s) {
+		pr_err("kmem_cache_free: Wrong slab cache. %s but object"
+			" is from  %s\n", page->slab->name, s->name);
+		WARN_ON_ONCE(1);
+		return;
+	}
+
 	slab_free(s, page, x, _RET_IP_);
 
 	trace_kmem_cache_free(_RET_IP_, x);