From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751000AbdAQBmH (ORCPT ); Mon, 16 Jan 2017 20:42:07 -0500 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:37511 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750734AbdAQBmG (ORCPT ); Mon, 16 Jan 2017 20:42:06 -0500 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: iamjoonsoo.kim@lge.com X-Original-SENDERIP: 10.177.222.138 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Tue, 17 Jan 2017 10:33:00 +0900 From: Joonsoo Kim To: Kyunghwan Kwon Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] slab: add a check for the first kmem_cache not to be destroyed Message-ID: <20170117013300.GA25940@js1304-P5Q-DELUXE> References: <20170116070459.43540-1-kwon@toanyone.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170116070459.43540-1-kwon@toanyone.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 16, 2017 at 04:04:59PM +0900, Kyunghwan Kwon wrote: > The first kmem_cache created at booting up is supposed neither mergeable > nor destroyable but was possible to destroy. So prevent it. > > Signed-off-by: Kyunghwan Kwon > --- > mm/slab_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 1dfc209..2d30ace 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -744,7 +744,7 @@ void kmem_cache_destroy(struct kmem_cache *s) > bool need_rcu_barrier = false; > int err; > > - if (unlikely(!s)) > + if (unlikely(!s) || s->refcount == -1) > return; Hello, Kyunghwan. Few lines below, s->refcount is checked. if (s->refcount) goto unlock; Am I missing something? Thanks.