Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932113AbVKCIM4 (ORCPT ); Thu, 3 Nov 2005 03:12:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932122AbVKCIM4 (ORCPT ); Thu, 3 Nov 2005 03:12:56 -0500 Received: from taurus.voltaire.com ([193.47.165.240]:56353 "EHLO taurus.voltaire.com") by vger.kernel.org with ESMTP id S932113AbVKCIMz (ORCPT ); Thu, 3 Nov 2005 03:12:55 -0500 Date: Thu, 3 Nov 2005 10:12:14 +0200 From: Gleb Natapov To: Hugh Dickins Cc: Benjamin Herrenschmidt , Petr Vandrovec , Nick Piggin , Linux Kernel Mailing List Subject: Re: Nick's core remove PageReserved broke vmware... Message-ID: <20051103081213.GC22185@minantech.com> References: <4367C25B.7010300@vc.cvut.cz> <4368097A.1080601@yahoo.com.au> <4368139A.30701@vc.cvut.cz> <1130965454.20136.50.camel@gaston> <1130967936.20136.65.camel@gaston> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-OriginalArrivalTime: 03 Nov 2005 08:12:54.0373 (UTC) FILETIME=[643D3150:01C5E04E] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1227 Lines: 28 On Wed, Nov 02, 2005 at 10:02:49PM +0000, Hugh Dickins wrote: > On Thu, 3 Nov 2005, Benjamin Herrenschmidt wrote: > > On Wed, 2005-11-02 at 21:41 +0000, Hugh Dickins wrote: > > > > > The only extant problem here is if the pages are private, and you > > > fork while this is going on, and the parent user process writes to the > > > area before completion: then COW leaves the child with the page being > > > DMAed into, giving the parent a copied page which may be incomplete. > > > > Won't happen, and if it does, it's a user error to rely on that working, > > so it doesn't matter. > > I wish everyone else would see it that way! (But some people do > have valid scenarios where it can't just be ruled out completely.) > I am one of those people :) Last discussion about this issue ended without resolution, but I remember you mentioned the possibility to leave ptes writable in parent during fork for private pages mapped for DMA. Is this approach acceptable? -- Gleb. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/