From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrei Vagin Subject: Re: [PATCH RESEND 2/2] pidns: Expose task pid_ns_for_children to userspace Date: Thu, 30 Mar 2017 18:04:10 -0700 Message-ID: <20170331010409.GA22895@outlook.office365.com> References: <149086931397.4388.9604947335273204415.stgit@localhost.localdomain> <149086967937.4388.471494976517194744.stgit@localhost.localdomain> <20170330150520.1bdf20e599ff464bda0776b9@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Return-path: Content-Disposition: inline In-Reply-To: <20170330150520.1bdf20e599ff464bda0776b9@linux-foundation.org> Sender: linux-fsdevel-owner@vger.kernel.org To: Andrew Morton Cc: Kirill Tkhai , agruenba@redhat.com, keescook@chromium.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, oleg@redhat.com, paul@paul-moore.com, ebiederm@xmission.com, avagin@openvz.org, linux-fsdevel@vger.kernel.org, mtk.manpages@gmail.com, luto@amacapital.net, mingo@kernel.org, serge@hallyn.com List-Id: linux-api@vger.kernel.org On Thu, Mar 30, 2017 at 03:05:20PM -0700, Andrew Morton wrote: > On Thu, 30 Mar 2017 13:27:59 +0300 Kirill Tkhai wrote: > > > pid_ns_for_children set by a task is known only to the task itself, > > and it's impossible to identify it from outside. > > > > It's a big problem for checkpoint/restore software like CRIU, > > because it can't correctly handle tasks, that do setns(CLONE_NEWPID) > > in proccess of their work. > > > > This patch solves the problem, and it exposes pid_ns_for_children > > to ns directory in standard way with the name "pid_for_children": > > > > ~# ls /proc/5531/ns -l | grep pid > > lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid -> pid:[4026531836] > > lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid_for_children -> pid:[4026532286] > > > > --- a/fs/proc/namespaces.c > > +++ b/fs/proc/namespaces.c > > @@ -23,6 +23,7 @@ static const struct proc_ns_operations *ns_entries[] = { > > #endif > > #ifdef CONFIG_PID_NS > > &pidns_operations, > > + &pidns_for_children_operations, > > #endif > > This interface should be documented somewhere under Documentation/. > But I can't immediately find where the /proc/pid/ns/ pseudo-files are > documented... I know that they are documented in man7/namespaces.7 https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man7/namespaces.7#n187 > >