From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755951AbcBIOaL (ORCPT ); Tue, 9 Feb 2016 09:30:11 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:32770 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400AbcBIOaI (ORCPT ); Tue, 9 Feb 2016 09:30:08 -0500 Date: Tue, 9 Feb 2016 15:30:05 +0100 From: Ingo Molnar To: Jan Beulich Cc: Peter Zijlstra , mingo@elte.hu, Thomas Gleixner , linux-kernel@vger.kernel.org, hpa@zytor.com Subject: Re: [PATCH v2] x86/mm: avoid premature success when changing page attributes Message-ID: <20160209143005.GA3665@gmail.com> References: <56A6615E02000078000CAC96@prv-mh.provo.novell.com> <56A8AD9E02000078000CB7CA@prv-mh.provo.novell.com> <56A8B64A02000078000CB830@prv-mh.provo.novell.com> <20160128084232.GA24464@gmail.com> <56B07AE902000078000CD54A@prv-mh.provo.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56B07AE902000078000CD54A@prv-mh.provo.novell.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jan Beulich wrote: > >>> On 28.01.16 at 09:42, wrote: > > Could we try a v3? > > Okay, I withdraw the patch: Upon further consideration it is note really clear > what the intended behavior of set_memory_*() on address ranges with mapping > holes is supposed to be. The original issue was with set_memory_nx() (called > from mark_rodata_ro()) stumbling across an unmapped region (resulting from an > out of tree change completely unmapping the kernel mappings of address ranges > passed to free_init_pages()). [...] So it still looks like a legitimate fix to me, even though your testcase was in an out of tree context: > [...] I simply don't have the time to check whether the unmapping done with > CONFIG_DEBUG_PAGEALLOC would have a similar effect. The net result in any event > were pages (past the hole) reported as problematic when CONFIG_DEBUG_WX is > enabled. Adding all the above information to the changelog addresses most of my complaints about it. You can also rephrase the DEBUG_PAGEALLOC bit to something like: I'm not completely sure about whether the unmapping done with CONFIG_DEBUG_PAGEALLOC would have a similar effect. as it's perfectly fine to submit fixes you couldn't fully test. Thanks, Ingo