From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756428Ab2CYP1o (ORCPT ); Sun, 25 Mar 2012 11:27:44 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:38686 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756356Ab2CYP1n (ORCPT ); Sun, 25 Mar 2012 11:27:43 -0400 Date: Sun, 25 Mar 2012 19:27:36 +0400 From: Vasiliy Kulikov To: Andrew Morton Cc: Arkadiusz =?utf-8?Q?Mi=C5=9Bkiewicz?= , linux-kernel@vger.kernel.org, Alexey Dobriyan Subject: Re: [PATCH] proc: fix mount -t proc -o AAA Message-ID: <20120325152736.GB4391@albatros> References: <201203220903.15360.a.miskiewicz@gmail.com> <20120323171058.GA3279@albatros> <20120323161504.dced28b9.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120323161504.dced28b9.akpm@linux-foundation.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 23, 2012 at 16:15 -0700, Andrew Morton wrote: > I'm surprised. "mount -o remount," doesn't work on a mounted > procfs, and nobody noticed until now? > > The patch looks OK - has it been tested with both valid and invalid > mount options? > > > I redid the changelog: > > > From: Vasiliy Kulikov > Subject: proc: fix mount -t proc -o AAA > > The proc_parse_options() call from proc_mount() runs only once at boot > time. So on any later mount attempt, any mount options are ignored > because ->s_root is already initialized. > > As a consequence, "mount -o remount," will ignore the options. No, remount works as it should. _mount_ doesn't work. Why it was not spotted: Live case is: 1) upstart and systemd don't use /etc/fstab for /proc when mounting it at the boot time. 2) dbus, etc. use /proc/ from the boot, so /proc cannot be umounted without dbus stop. So, to apply hidepid=X without system reboot procfs should be remounted instead of umount+mount. > To fix this, parse the mount options unconditionally. -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments