From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932705Ab2DSWKD (ORCPT ); Thu, 19 Apr 2012 18:10:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32525 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932375Ab2DSWKA (ORCPT ); Thu, 19 Apr 2012 18:10:00 -0400 Date: Fri, 20 Apr 2012 00:09:19 +0200 From: Oleg Nesterov To: Cyrill Gorcunov Cc: Konstantin Khlebnikov , "akpm@linux-foundation.org" , "keescook@chromium.org" , "kosaki.motohiro@jp.fujitsu.com" , "matthltc@us.ibm.com" , "tj@kernel.org" , Pavel Emelianov , "linux-kernel@vger.kernel.org" Subject: Re: + c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm- num_exe_file_vmas-removal.patch added to -mm tree Message-ID: <20120419220918.GA5474@redhat.com> References: <20120419185221.E8ED6A055E@akpm.mtv.corp.google.com> <20120419192005.GA13558@redhat.com> <20120419210033.GO1893@moon> <20120419211216.GA2200@redhat.com> <4F9087D0.60709@openvz.org> <20120419215109.GA4896@redhat.com> <20120419220201.GR1893@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120419220201.GR1893@moon> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/20, Cyrill Gorcunov wrote: > > Guys, while I more-less agree with Matt about single-shot behaviour > > [ let me copy my and his email > > >> With mm->exe_file this prctl option become a one-shot > >> only, and while at moment our user-space tool can perfectly > >> live with that I thought that there is no strict need to > >> limit the option this way from the very beginning. > >> > > As far as backward compatibility, isn't it better to lift that restriction > > later rather than add it? I think the latter would very likely "break" > > things whereas the former would not. > > > > I also prefer that restriction because it establishes a bound on how > > frequently the symlink can change. Keeping it a one-shot deal makes the > > values that show up in tools like top more reliable for admins. > ] > > I guess maybe it's time to drop one-shot requirement and as result > we can drop MMF_EXE_FILE_CHANGED bit completely, Plus perhaps we can remove this for_each_vma check? > making overall code > simplier? Personally I'd certainly prefer this ;) But let me repeat to avoid the confusion. I am fine either way, I am not going to discuss this again unless I see something which looks technically wrong. And the current MMF_EXE_FILE_CHANGED doesn't look right even if the problem is minor. Oleg.