Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753742AbZGAHfk (ORCPT ); Wed, 1 Jul 2009 03:35:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752797AbZGAHfc (ORCPT ); Wed, 1 Jul 2009 03:35:32 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:57775 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972AbZGAHfb (ORCPT ); Wed, 1 Jul 2009 03:35:31 -0400 Date: Wed, 1 Jul 2009 00:31:41 -0700 From: Sukadev Bhattiprolu To: Oleg Nesterov , roland@redhat.com, "Eric W. Biederman" , Oren Laadan Cc: serue@us.ibm.com, Alexey Dobriyan , Containers , linux-kernel@vger.kernel.org Subject: [RFC][PATCH] Disable CLONE_PARENT for init Message-ID: <20090701073140.GA14284@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1870 Lines: 48 Disable CLONE_PARENT for init When global or container-init processes use CLONE_PARENT, they create a multi-rooted process tree. Besides, if the siblings of init exit, the SIGCHLD is not sent to init process resulting in the zombies sticking around indefinitely. So disable CLONE_PARENT for init. Lightly tested, RFC patch :-) Changelog[v2]: - Simplify patch description based on comments from Eric Biederman and Oleg Nesterov. - [Oleg Nesterov] Use SIGNAL_UNKILLABLE instead of is_global_init() Signed-off-by: Sukadev Bhattiprolu Acked-by: Roland McGrath --- kernel/fork.c | 11 +++++++++++ 1 file changed, 11 insertions(+) Index: linux-mmotm/kernel/fork.c =================================================================== --- linux-mmotm.orig/kernel/fork.c 2009-06-30 23:01:06.000000000 -0700 +++ linux-mmotm/kernel/fork.c 2009-06-30 23:13:53.000000000 -0700 @@ -974,6 +974,17 @@ static struct task_struct *copy_process( if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) return ERR_PTR(-EINVAL); + /* + * Swapper process sets the handler for SIGCHLD to SIG_DFL. If init + * creates a sibling and the sibling exits, the SIGCHLD is sent to + * the swapper (since the swapper's handler for SIGCHLD is SIG_DFL). + * But since the swapper does not reap its children, the zombie will + * remain forever. So prevent init from using CLONE_PARENT. + */ + if ((clone_flags & CLONE_PARENT) && + current->signal->flags & SIGNAL_UNKILLABLE) + return ERR_PTR(-EINVAL); + retval = security_task_create(clone_flags); if (retval) goto fork_out; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/