From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: Re: [PATCH 1/15] Move exit_task_namespaces() Date: Mon, 6 Aug 2007 13:54:21 +0400 Message-ID: <20070806095421.GA85@tv-sign.ru> References: <46A8B37B.6050108@openvz.org> <46A8B3C4.5080601@openvz.org> <20070802162023.GB137@tv-sign.ru> <46B6D52C.3010405@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <46B6D52C.3010405-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Pavel Emelyanov Cc: Linux Containers List-Id: containers.vger.kernel.org On 08/06, Pavel Emelyanov wrote: > Oleg Nesterov wrote: > >On 07/26, Pavel Emelyanov wrote: > >>The reason to release namespaces after reparenting is that when task > >>exits it may send a signal to its parent (SIGCHLD), but if the parent > >>has already exited its namespaces there will be no way to decide what > >>pid to dever to him - parent can be from different namespace. > > > >I almost forgot about this one... > > > >After reading the whole series, I can't understand the above explanation > >any longer. The parent can't be from different namespace, either we have > >another sub-thread, or we reparent the child to /sbin/init which should > >be from the same namespace. > > If the child that is a new namespace's init is exiting its parent is from the > different namespace. In that case it doesn't have childs. The were SIGKILL'ed before exit_notify(). > Moreover, we will probably want to implement "entering" > the pid namespace, so having tasks with parents from another namespace will > be OK. Well. I saw this word "entering", but I don't know the meaning. Just curious, could you explain? And, if an exiting task has a child which is already from another namespace, why can't we release our namespace before re-parenting? I guess I need to know what "entering" means to understand this... Oleg.