From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-mm@kvack.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] mm/slub: fix memory leak with using debugfs_lookup()
Date:   Thu,  2 Feb 2023 15:20:22 +0100
Message-Id: <20230202142022.2300096-1-gregkh@linuxfoundation.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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 <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/slub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 13459c69095a..4880e461fcc5 100644
--- a/mm/slub.c
+++ b/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)
-- 
2.39.1