Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161438AbbKENx6 (ORCPT ); Thu, 5 Nov 2015 08:53:58 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:50828 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161361AbbKENxz (ORCPT ); Thu, 5 Nov 2015 08:53:55 -0500 Subject: Re: [Xen-devel] Linux 4.4 MW: Boot under Xen fails with CONFIG_DEBUG_WX enabled: RIP: ptdump_walk_pgd_level_core To: Sander Eikelenboom , Stephen Smalley References: <9184aedc84bf5274c290183fa60b48e9@eikelenboom.it> <563A29C4.7020400@tycho.nsa.gov> <60febac0220bd2b5df2fd0d86c8d40ae@eikelenboom.it> <563A52CD.5030903@tycho.nsa.gov> <8bbf050578e9254ac3bf1d941dc0fb19@eikelenboom.it> <563A910F.7060008@oracle.com> <80b3ed527b208d28ee05fb627bc28d91@eikelenboom.it> Cc: linux-kernel@vger.kernel.org, x86@kernel.org, David Vrabel , xen-devel@lists.xen.org, mingo.kernel.org@gmail.com From: Boris Ostrovsky Message-ID: <563B5F64.1010806@oracle.com> Date: Thu, 5 Nov 2015 08:53:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <80b3ed527b208d28ee05fb627bc28d91@eikelenboom.it> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1288 Lines: 38 On 11/05/2015 04:13 AM, Sander Eikelenboom wrote: > > It makes "cat /sys/kernel/debug/kernel_page_tables" work and > prevents a kernel with CONFIG_DEBUG_WX=y from crashing at boot. Great. Our nightly runs also failed spectacularly due to this bug. > > It now does give a warning about an insecure W+X mapping, so > CONFIG_DEBUG_WX=y > seems to be working. No idea how to interpret it though (and if it's a > legit > warning). > > -- > Sander > > [ 19.034706] Freeing unused kernel memory: 1104K (ffffffff822fc000 - > ffffffff82410000) > [ 19.041339] Write protecting the kernel read-only data: 18432k > [ 19.052596] Freeing unused kernel memory: 1144K (ffff880001ae2000 - > ffff880001c00000) > [ 19.060285] Freeing unused kernel memory: 1560K (ffff88000207a000 - > ffff880002200000) > [ 19.067079] ------------[ cut here ]------------ > [ 19.073931] WARNING: CPU: 5 PID: 1 at > arch/x86/mm/dump_pagetables.c:225 note_page+0x619/0x7e0() Yes, this apparently is a known issue: https://lkml.org/lkml/2015/11/4/476 -boris -- 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/