From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932482AbYETQQQ (ORCPT ); Tue, 20 May 2008 12:16:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753578AbYETQQA (ORCPT ); Tue, 20 May 2008 12:16:00 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:40907 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753540AbYETQQA (ORCPT ); Tue, 20 May 2008 12:16:00 -0400 Date: Tue, 20 May 2008 12:10:47 -0400 From: Jeff Dike To: Tom Spink Cc: LKML Subject: Re: UML fails to locate address space Message-ID: <20080520161047.GA9598@c2.user-mode-linux.org> References: <7b9198260805200408k1d6b70a8xc7e4c24106e5020f@mail.gmail.com> <20080520135238.GB6990@c2.user-mode-linux.org> <7b9198260805200659p6ed28403t9b0b0ea995f158d5@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b9198260805200659p6ed28403t9b0b0ea995f158d5@mail.gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 20, 2008 at 02:59:14PM +0100, Tom Spink wrote: > Attached. I guess the line of interest is: > > mmap2(NULL, 4096, PROT_READ|PROT_WRITE, > MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = -1 EACCES (Permission > denied) Yup. Can you try three things: check the maps file for any arbitrary process (i.e. /proc/$$/maps) and see if there's anything mapped at 0 gdb UML, stop it at that mmap, check its maps file and see if there's anything mapped at 0 send me a pointer to the patches that Ubuntu has applied on top of the stock kernel - I'm suspicious that they special-cased page zero in order to ensure that NULL pointer dereferences cause faults. You can test this last theory by initializing bottom to 4096 instead of 0. Jeff -- Work email - jdike at linux dot intel dot com