From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756112AbbLAQqy (ORCPT ); Tue, 1 Dec 2015 11:46:54 -0500 Received: from mail-yk0-f171.google.com ([209.85.160.171]:33225 "EHLO mail-yk0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751704AbbLAQqx (ORCPT ); Tue, 1 Dec 2015 11:46:53 -0500 Date: Tue, 1 Dec 2015 11:46:49 -0500 From: Tejun Heo To: "Serge E. Hallyn" Cc: serge@hallyn.com, linux-kernel@vger.kernel.org, adityakali@google.com, linux-api@vger.kernel.org, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, lxc-devel@lists.linuxcontainers.org, akpm@linux-foundation.org, ebiederm@xmission.com Subject: Re: [PATCH 7/8] cgroup: mount cgroupns-root when inside non-init cgroupns Message-ID: <20151201164649.GD12922@mtj.duckdns.org> References: <1447703505-29672-1-git-send-email-serge@hallyn.com> <1447703505-29672-8-git-send-email-serge@hallyn.com> <20151124171610.GS17033@mtj.duckdns.org> <20151127051745.GA24521@mail.hallyn.com> <20151130150938.GF3535@mtj.duckdns.org> <20151201040704.GA31067@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151201040704.GA31067@mail.hallyn.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, Serge. On Mon, Nov 30, 2015 at 10:07:04PM -0600, Serge E. Hallyn wrote: > So actually the way the code is now, the first mount cannot > be done from a non-init user namespace; and kernfs_obtain_root() > is only called from non-init user namespace. So can we assume > that the root dentry will be instantiated? (or can it get > evicted?) > > If we can assume that then most of that fn can go away. The v2 hierarchy is always mounted and non-init ns shouldn't be able to create new v1 hierarchies, so the root dentry should always be there. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 7/8] cgroup: mount cgroupns-root when inside non-init cgroupns Date: Tue, 1 Dec 2015 11:46:49 -0500 Message-ID: <20151201164649.GD12922@mtj.duckdns.org> References: <1447703505-29672-1-git-send-email-serge@hallyn.com> <1447703505-29672-8-git-send-email-serge@hallyn.com> <20151124171610.GS17033@mtj.duckdns.org> <20151127051745.GA24521@mail.hallyn.com> <20151130150938.GF3535@mtj.duckdns.org> <20151201040704.GA31067@mail.hallyn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20151201040704.GA31067-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Serge E. Hallyn" Cc: serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, adityakali-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lxc-devel-cunTk1MwBs9qMoObBWhMNEqPaTDuhLve2LY78lusg7I@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org List-Id: linux-api@vger.kernel.org Hey, Serge. On Mon, Nov 30, 2015 at 10:07:04PM -0600, Serge E. Hallyn wrote: > So actually the way the code is now, the first mount cannot > be done from a non-init user namespace; and kernfs_obtain_root() > is only called from non-init user namespace. So can we assume > that the root dentry will be instantiated? (or can it get > evicted?) > > If we can assume that then most of that fn can go away. The v2 hierarchy is always mounted and non-init ns shouldn't be able to create new v1 hierarchies, so the root dentry should always be there. Thanks. -- tejun