From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756417Ab2DSVAk (ORCPT ); Thu, 19 Apr 2012 17:00:40 -0400 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:59657 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751685Ab2DSVAi (ORCPT ); Thu, 19 Apr 2012 17:00:38 -0400 Date: Fri, 20 Apr 2012 01:00:33 +0400 From: Cyrill Gorcunov To: Oleg Nesterov Cc: akpm@linux-foundation.org, khlebnikov@openvz.org, keescook@chromium.org, kosaki.motohiro@jp.fujitsu.com, matthltc@us.ibm.com, tj@kernel.org, xemul@parallels.com, 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: <20120419210033.GO1893@moon> References: <20120419185221.E8ED6A055E@akpm.mtv.corp.google.com> <20120419192005.GA13558@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120419192005.GA13558@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 19, 2012 at 09:20:05PM +0200, Oleg Nesterov wrote: > On 04/19, Andrew Morton wrote: > > > > From: Konstantin Khlebnikov > > Subject: c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal > > > > [ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ] > > > > After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final > > mmput(), it never becomes NULL while task is alive. > > > > We can check for other mapped files in mm instead of checking > > mm->num_exe_file_vmas, and mark mm with flag MMF_EXE_FILE_CHANGED in order > > to forbid second changing of mm->exe_file. > > I lost the track a long ago. > > Just one question, what does this "forbid second changing" actually mean? Heh :) Oleg, it was actually your idea to make this feature "one-shot". Once exe-file changed to a new value, it can't be changed again. The reason was to bring at least minimum disturbance in sysadmins life. Cyrill