From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758481Ab0FRI0o (ORCPT ); Fri, 18 Jun 2010 04:26:44 -0400 Received: from 101-97.80-90.static-ip.oleane.fr ([90.80.97.101]:38999 "EHLO bohort.kerlabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758209Ab0FRI0m (ORCPT ); Fri, 18 Jun 2010 04:26:42 -0400 Date: Fri, 18 Jun 2010 10:27:38 +0200 From: Louis Rilling To: Oleg Nesterov Cc: "Eric W. Biederman" , Pavel Emelyanov , Andrew Morton , Pavel Emelyanov , Linux Containers , linux-kernel@vger.kernel.org Subject: Re: [PATCH] procfs: Do not release pid_ns->proc_mnt too early Message-ID: <20100618082738.GE16877@hawkmoon.kerlabs.com> Mail-Followup-To: Oleg Nesterov , "Eric W. Biederman" , Pavel Emelyanov , Andrew Morton , Pavel Emelyanov , Linux Containers , linux-kernel@vger.kernel.org References: <1276706068-18567-1-git-send-email-louis.rilling@kerlabs.com> <4C19F0A3.2050707@parallels.com> <20100617213638.GB4182@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_bohort-9188-1276849594-0001-2" Content-Disposition: inline In-Reply-To: <20100617213638.GB4182@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --=_bohort-9188-1276849594-0001-2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 17/06/10 23:36 +0200, Oleg Nesterov wrote: > On 06/17, Eric W. Biederman wrote: > > > > The task->children isn't changed until __unhash_process() which runs > > after flush_proc_task(). >=20 > Yes. But this is only the current implementation detail. > It would be nice to cleanup the code so that EXIT_DEAD tasks are > never sit in ->children list. >=20 > > So we should be able to come up with > > a variant of do_wait() that zap_pid_ns_processes can use that does > > what we need. >=20 > See above... >=20 > Even if we modify do_wait() or add the new variant, how the caller > can wait for EXIT_DEAD tasks? I don't think we want to modify > release_task() to do __wake_up_parent() or something similar. Indeed, I was thinking about calling __wake_up_parent() from release_task() once parent->children becomes empty. Not sure about the performance impact though. Maybe some WAIT_NO_CHILDREN f= lag in parent->signal could limit it. But if EXIT_DEAD children are removed from ->children before release_task(), I'm afraid that this becomes impossible. Thanks, Louis --=20 Dr Louis Rilling Kerlabs Skype: louis.rilling Batiment Germanium Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes http://www.kerlabs.com/ 35700 Rennes --=_bohort-9188-1276849594-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkwbLfoACgkQVKcRuvQ9Q1SQBgCfZgPTVMU0uatEqwfbhKVwocIr MIkAn2Ai6o8YIJ/PvAddBZ+DAvf2pzXi =Yg5/ -----END PGP SIGNATURE----- --=_bohort-9188-1276849594-0001-2--