From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752561AbXCSTYZ (ORCPT ); Mon, 19 Mar 2007 15:24:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752467AbXCSTYZ (ORCPT ); Mon, 19 Mar 2007 15:24:25 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:43917 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752561AbXCSTYY (ORCPT ); Mon, 19 Mar 2007 15:24:24 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: David Howells Cc: Hugh Dickins , bryan.wu@analog.com, Robin Holt , "Kawai, Hidehiro" , Andrew Morton , kernel list , Pavel Machek , Alan Cox , Masami Hiramatsu , sugita , Satoshi OSHIMA , haoki@redhat.com, Robin Getz Subject: Re: Move to unshared VMAs in NOMMU mode? References: <3378.1173204813@redhat.com> <20070216165042.GB409@lnx-holt.americas.sgi.com> <45D5B483.3020502@hitachi.com> <45D5B2E3.3030607@hitachi.com> <20368.1171638335@redhat.com> <18817.1171656543@redhat.com> <29317.1172931029@redhat.com> <12852.1173449522@redhat.com> <12838.1173998825@redhat.com> Date: Mon, 19 Mar 2007 13:23:17 -0600 In-Reply-To: <12838.1173998825@redhat.com> (David Howells's message of "Thu, 15 Mar 2007 22:47:05 +0000") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I'm just trying to digest this a little. As I understand your description for non-shared mappings the VMAs are per process. For shared mappings you share in some sense the page cache. My gut feel says just keep a vma per process of the regions the process has and do the appropriate book keeping and all will be fine. For shm_nattach it looks like you simply are not calling the open/close methods on fork (because you have a shared pool of vmas). Eric