slub: improve kmem_cache_destroy() error message

As pointed out by Ingo, the SLUB warning of calling kmem_cache_destroy()
with cache that still has objects triggers in practice. So turn this
WARN_ON() into a nice SLUB specific error message to avoid people
confusing it to a SLUB bug.

Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

1 files changed, 5 insertions, 2 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 39592b5ce68a..378d3f1b548f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2426,8 +2426,11 @@ void kmem_cache_destroy(struct kmem_cache *s)
         if (!s->refcount) {
                 list_del(&s->list);
                 up_write(&slub_lock);
-                if (kmem_cache_close(s))
-                        WARN_ON(1);
+                if (kmem_cache_close(s)) {
+                        printk(KERN_ERR "SLUB %s: %s called for cache that "
+                                "still has objects.\n", s->name, __func__);
+                        dump_stack();
+                }
                 sysfs_slab_remove(s);
         } else
                 up_write(&slub_lock);