From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: Re: [PATCH 3/20] Introduce MS_KERNMOUNT flag Date: Sat, 11 Aug 2007 15:22:00 +0400 Message-ID: <20070811112200.GA121@tv-sign.ru> References: <46BC506B.mailGIV1AXDXM@openvz.org> <20070811034721.GB22216@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20070811034721.GB22216@infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig , xemul@openvz.org, akpm@osdl.org, devel@openvz.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org, sukadev@us.ibm.com List-Id: containers.vger.kernel.org On 08/11, Christoph Hellwig wrote: > > On Fri, Aug 10, 2007 at 03:47:55PM +0400, xemul@openvz.org wrote: > > This flag tells the .get_sb callback that this is a kern_mount() call > > so that it can trust *data pointer to be valid in-kernel one. If this > > flag is passed from the user process, it is cleared since the *data > > pointer is not a valid kernel object. > > > > Running a few steps forward - this will be needed for proc to create the > > superblock and store a valid pid namespace on it during the namespace > > creation. The reason, why the namespace cannot live without proc mount > > is described in the appropriate patch. > > I don't like this at all. We should never pass kernel and userspace > addresses through the same pointer. Maybe add an additional argument > to the get_sb prototype instead. But this whole idea of mounting /proc > from kernelspace sounds like a really bad idea to me. /proc should > never be mounted from the kernel but always normally from userspace. Can't comment because I don't understand vfs at all, and perhaps I just misunderstood you. But could you clarify? We already create internal proc mount from kernel space, proc_root_init() does this. With this series we are doing the same when a new namespace is created. Thanks, Oleg.