Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964809AbWBMTQh (ORCPT ); Mon, 13 Feb 2006 14:16:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964810AbWBMTQh (ORCPT ); Mon, 13 Feb 2006 14:16:37 -0500 Received: from sj-iport-5.cisco.com ([171.68.10.87]:2448 "EHLO sj-iport-5.cisco.com") by vger.kernel.org with ESMTP id S964809AbWBMTQg (ORCPT ); Mon, 13 Feb 2006 14:16:36 -0500 X-IronPort-AV: i="4.02,109,1139212800"; d="scan'208"; a="255214349:sNHT33563904" To: Linus Torvalds Cc: "Michael S. Tsirkin" , Nick Piggin , Gleb Natapov , Benjamin Herrenschmidt , Linux Kernel Mailing List , openib-general@openib.org, Petr Vandrovec , Badari Pulavarty , Hugh Dickins Subject: Re: [openib-general] Re: madvise MADV_DONTFORK/MADV_DOFORK X-Message-Flag: Warning: May contain useful information References: <20060213154114.GO32041@mellanox.co.il> From: Roland Dreier Date: Mon, 13 Feb 2006 11:16:32 -0800 In-Reply-To: (Linus Torvalds's message of "Mon, 13 Feb 2006 11:05:37 -0800 (PST)") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) XEmacs/21.4.17 (Jumbo Shrimp, linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 X-OriginalArrivalTime: 13 Feb 2006 19:16:33.0574 (UTC) FILETIME=[00779460:01C630D2] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1046 Lines: 27 Linus> Why? Linus> That VM_DONTCOPY _is_ DONTFORK. Linus> Don't add a new useless DONTFORK that doesn't have any Linus> value. VM_DONTCOPY is hardly used in the kernel, so the semantics aren't very precisely defined. But the idea is that a driver setting VM_DONTCOPY probably has a good reason for doing it, and we don't want userspace to be able to erase that flag through madvise(). As Hugh said in his suggestion for a better changelog entry: > Explain that MADV_DONTFORK should be reversible, hence > MADV_DOFORK; but should not be reversible on areas a driver has > so marked, hence VM_DONTFORK distinct from VM_DONTCOPY. Perhaps we don't care for now, and we should wait and add VM_KERNEL_DONTCOPY later if we really need it. I honestly don't know. - Roland - 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/