mm/slub: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Hyeonggon Yoo <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Acked-by: David Rientjes <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

Author: gregkh

mm/slub.c

@@ -6449,7 +6449,7 @@ static void debugfs_slab_add(struct kmem_cache *s)
 
 void debugfs_slab_release(struct kmem_cache *s)
 {
-	debugfs_remove_recursive(debugfs_lookup(s->name, slab_debugfs_root));
+	debugfs_lookup_and_remove(s->name, slab_debugfs_root);
 }
 
 static int __init slab_debugfs_init(void)