Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261444AbVE2VQt (ORCPT ); Sun, 29 May 2005 17:16:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261445AbVE2VQt (ORCPT ); Sun, 29 May 2005 17:16:49 -0400 Received: from stark.xeocode.com ([216.58.44.227]:20689 "EHLO stark.xeocode.com") by vger.kernel.org with ESMTP id S261444AbVE2VQq (ORCPT ); Sun, 29 May 2005 17:16:46 -0400 To: Arjan van de Ven Cc: Chris Wright , Linus Torvalds , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] prevent NULL mmap in topdown model References: <20050519064657.GH23013@shell0.pdx.osdl.net> <1116490511.6027.25.camel@laptopd505.fenrus.org> In-Reply-To: <1116490511.6027.25.camel@laptopd505.fenrus.org> From: Greg Stark Organization: The Emacs Conspiracy; member since 1992 Date: 29 May 2005 17:16:33 -0400 Message-ID: <87u0klybpq.fsf@stark.xeocode.com> User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 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 Content-Length: 900 Lines: 18 Arjan van de Ven writes: > On Wed, 2005-05-18 at 23:46 -0700, Chris Wright wrote: > > sure. Making it *impossible* to mmap that page is bad. People should be > able to do that if they really want to, just doing it if they don't ask > for it is bad. > > There are plenty of reasons people may want that page mmaped, one of > them being that the compiler can then do more speculative loads around > null pointer checks. Not saying it's a brilliant idea always, but making > such things impossible makes no sense. More realistically, iirc either Wine or dosemu, i forget which, actually has to map page 0 to work properly. -- greg - 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/