From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751702AbaHVUqa (ORCPT ); Fri, 22 Aug 2014 16:46:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36739 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751327AbaHVUq3 (ORCPT ); Fri, 22 Aug 2014 16:46:29 -0400 Date: Fri, 22 Aug 2014 13:46:28 -0700 From: Andrew Morton To: Cyrill Gorcunov Cc: linux-kernel@vger.kernel.org, keescook@chromium.org, tj@kernel.org, avagin@openvz.org, ebiederm@xmission.com, hpa@zytor.com, serge.hallyn@canonical.com, xemul@parallels.com, segoon@openwall.com, kamezawa.hiroyu@jp.fujitsu.com, mtk.manpages@gmail.com, jln@google.com Subject: Re: [patch 4/4] prctl: PR_SET_MM -- Introduce PR_SET_MM_MAP operation, v3 Message-Id: <20140822134628.5df9cda87d744e35d794b5c2@linux-foundation.org> In-Reply-To: <20140822203809.GC25918@moon> References: <20140804172255.109539743@openvz.org> <20140804172610.965949916@openvz.org> <20140821155115.8433bb37bf631b8ae8340f84@linux-foundation.org> <20140822063242.GI14072@moon> <20140821234912.f007e2fb.akpm@linux-foundation.org> <20140822203809.GC25918@moon> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 23 Aug 2014 00:38:09 +0400 Cyrill Gorcunov wrote: > > > > Or will we? What happens if we later decide that some additional field > > needs to be added? Do we version the interface? Add a new prctl() > > mode? Let's cook up a plan for that and at least add to changelog? > > I don't expect to change it anytime soon but we still have an option -- > if we decide to extend or shrink it we always can use sizeof/offsetof > helpers to check which exactly version userspace asks us to use. How does that work? We just have a blob of bytes coming in from userspace. > As far as I understand the mm_struct is not the structure which > changes that frequently, right? We might find existing things which criu wants to access. And criu lives forever, yes? The mm_struct is likely to change over that time period ;)