From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754475Ab0GHOnR (ORCPT ); Thu, 8 Jul 2010 10:43:17 -0400 Received: from kroah.org ([198.145.64.141]:33346 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753235Ab0GHOnQ (ORCPT ); Thu, 8 Jul 2010 10:43:16 -0400 Date: Thu, 8 Jul 2010 07:43:17 -0700 From: Greg KH To: Tvrtko Ursulin Cc: "linux-kernel@vger.kernel.org" , Al Viro Subject: Re: BUG: Securityfs and bind mounts (2.6.34) Message-ID: <20100708144317.GA2364@kroah.com> References: <201007081112.41252.tvrtko.ursulin@sophos.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201007081112.41252.tvrtko.ursulin@sophos.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 08, 2010 at 11:12:41AM +0100, Tvrtko Ursulin wrote: > > Hi guys, > > If I overlay a file in securityfs using mount --bind with a file from > a regular filesystem, should I be allowed to rmmod the module which > registered the overlaid securityfs file? Why would you want to overlay securityfs in the first place? And you might be able to rmmod the module, but I didn't think that security modules were able to be unloaded anymore. > I was able to do that, then I > unmounted the bind mount, and then when attempting to unmount > securityfs hit a BUG at > fs/dcache.c:676 (see below). It would have made more sense to first > umount the overlay file and then remove the module which registered > with securityfs, nevertheless should kernel crash in this case? Probably not, but then again, you did something that you shouldn't have, so perhaps it is telling you not to do such a thing in the future :) thanks, greg k-h