From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753107Ab3LBR0V (ORCPT ); Mon, 2 Dec 2013 12:26:21 -0500 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:37628 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752957Ab3LBR0S (ORCPT ); Mon, 2 Dec 2013 12:26:18 -0500 X-Sasl-enc: 72u8k/g11ukpwBt48p5YXjdw8aUTRunF/ZZZ915pbx8e 1386005176 Date: Mon, 2 Dec 2013 09:26:15 -0800 From: Greg KH To: Christoph Lameter Cc: Thomas Gleixner , Russell King - ARM Linux , Pablo Neira Ayuso , Sasha Levin , Patrick McHardy , kadlec@blackhole.kfki.hu, "David S. Miller" , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, LKML , linux-mm@kvack.org, Andrew Morton Subject: Re: netfilter: active obj WARN when cleaning up Message-ID: <20131202172615.GA4722@kroah.com> References: <20131127113939.GL16735@n2100.arm.linux.org.uk> <20131127133231.GO16735@n2100.arm.linux.org.uk> <20131127134015.GA6011@n2100.arm.linux.org.uk> <20131127233415.GB19270@kroah.com> <00000142b4282aaf-913f5e4c-314c-4351-9d24-615e66928157-000000@email.amazonses.com> <20131202164039.GA19937@kroah.com> <00000142b4514eb5-2e8f675d-0ecc-423b-9906-58c5f383089b-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00000142b4514eb5-2e8f675d-0ecc-423b-9906-58c5f383089b-000000@email.amazonses.com> 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, Dec 02, 2013 at 05:18:16PM +0000, Christoph Lameter wrote: > On Mon, 2 Dec 2013, Greg KH wrote: > > > On Mon, Dec 02, 2013 at 04:33:20PM +0000, Christoph Lameter wrote: > > > On Wed, 27 Nov 2013, Greg KH wrote: > > > > > > > Just make the kobject "dynamic" instead of embedded in struct kmem_cache > > > > and all will be fine. I can't believe this code has been broken for > > > > this long. > > > > > > The slub code is was designed to use an embedded structure since we > > > only get the kobj pointer passed to us from sysfs. If kobj is not > > > embedded then how can we get from the sysfs object to the kmem_cache > > > structure from the sysfs callbacks? Sysfs was designed to have embedded > > > objects as far as I can recall. > > > > Yes, it's designed to have embedded objects, so then use it that way and > > clean up the structure when the kobject goes away. Don't use a > > different reference count for your structure than the one in the kobject > > and think that all will be fine. > > We need our own reference count. So we just have to defer the > release of the kmem_cache struct until the ->release callback is > triggered. The put of the embedded kobject must be the last action on the > kmem_cache structure which will then trigger release and that will > trigger the kmem_cache_free(). > Ok, that sounds reasonable, or you can just create a "tiny" structure for the kobject that has a pointer back to your kmem_cache structure that you can then reference from the show/store functions. Either is fine with me. thanks, greg k-h