From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965157AbVHJPZl (ORCPT ); Wed, 10 Aug 2005 11:25:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965159AbVHJPZl (ORCPT ); Wed, 10 Aug 2005 11:25:41 -0400 Received: from silver.veritas.com ([143.127.12.111]:33384 "EHLO silver.veritas.com") by vger.kernel.org with ESMTP id S965157AbVHJPZk (ORCPT ); Wed, 10 Aug 2005 11:25:40 -0400 Date: Wed, 10 Aug 2005 16:27:31 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Gleb Natapov cc: "Michael S. Tsirkin" , Roland Dreier , linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: [openib-general] Re: [PATCH repost] PROT_DONTCOPY: ifiniband uverbs fork support In-Reply-To: <20050810132611.GP16361@minantech.com> Message-ID: References: <20050719165542.GB16028@mellanox.co.il> <20050725171928.GC12206@mellanox.co.il> <20050726133553.GA22276@mellanox.co.il> <20050810083943.GM16361@minantech.com> <20050810132611.GP16361@minantech.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 10 Aug 2005 15:25:38.0358 (UTC) FILETIME=[C2DE2560:01C59DBF] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Aug 2005, Gleb Natapov wrote: > On Wed, Aug 10, 2005 at 02:22:40PM +0100, Hugh Dickins wrote: > > > > Your stack example is a good one: if we end up setting VM_DONTCOPY on > > the user stack, then I don't think fork's child will get very far without > > hitting a SIGSEGV. > > I know, but I prefer child SIGSEGV than silent data corruption. Most people will share your preference, but neither is satisfactory. > In most cases child will exec immediately after fork so no problem > in this case. In most(?) cases it won't even be able to exec before the SIGSEGV. Hugh