Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751111AbVKNMlg (ORCPT ); Mon, 14 Nov 2005 07:41:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751112AbVKNMlg (ORCPT ); Mon, 14 Nov 2005 07:41:36 -0500 Received: from gold.veritas.com ([143.127.12.110]:32354 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S1751111AbVKNMlf (ORCPT ); Mon, 14 Nov 2005 07:41:35 -0500 Date: Mon, 14 Nov 2005 12:40:14 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: "Michael S. Tsirkin" cc: Gleb Natapov , Benjamin Herrenschmidt , Petr Vandrovec , Nick Piggin , Badari Pulavarty , Linux Kernel Mailing List Subject: Re: Nick's core remove PageReserved broke vmware... In-Reply-To: <20051114123432.GQ20871@mellanox.co.il> Message-ID: References: <20051114122759.GE5492@minantech.com> <20051114123432.GQ20871@mellanox.co.il> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 14 Nov 2005 12:41:28.0941 (UTC) FILETIME=[BBD061D0:01C5E918] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1253 Lines: 35 On Mon, 14 Nov 2005, Michael S. Tsirkin wrote: > Quoting Gleb Natapov : > > On Mon, Nov 14, 2005 at 02:25:35PM +0200, Michael S. Tsirkin wrote: > > > > > > There's one thing that I have thought about: what happens > > > if I set DONTFORK on a page which already has COW set > > > (e.g. after fork)? > > > > > > It seems that the right thing would be to force a page copy - > > > otherwise the page can get copied on write. No, keep it simple, DONTFORK simply marks the area as not to be included in a fork from that time onwards (until perhaps a DOFORK follows). > > I thought about it. It should not happen for OpenIB since get_user_pages > > will break COW for us and I don't think we should complicate DONTFORK > > implementation by doing break during madvise(). Exactly. > Hmm, I assumed we call madvise before driver does get_user_pages, > otherwise an application could fork in between. I think we're all of us assuming that. > Should we worry about this? About what? Hugh - 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/