From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933504Ab0CLORi (ORCPT ); Fri, 12 Mar 2010 09:17:38 -0500 Received: from smtp.citrix.com ([66.165.176.89]:11368 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758196Ab0CLORh (ORCPT ); Fri, 12 Mar 2010 09:17:37 -0500 X-IronPort-AV: E=Sophos;i="4.49,626,1262581200"; d="scan'208";a="7537738" Subject: Re: patch x86-xen-disable-highmem-pte-allocation-even-when-config_highpte-y.patch added to 2.6.33-stable tree From: Ian Campbell To: Stefan Lippers-Hollmann CC: "gregkh@suse.de" , "linux-kernel@vger.kernel.org" , "hpa@zytor.com" , "jeremy@goop.org" , "mingo@elte.hu" , "pasik@iki.fi" , "xen-devel@lists.xensource.com" , "stable@kernel.org" In-Reply-To: <201003121508.54384.s.L-H@gmx.de> References: <12683359492650@site> <201003121508.54384.s.L-H@gmx.de> Content-Type: text/plain; charset="UTF-8" Organization: Citrix Systems, Inc. Date: Fri, 12 Mar 2010 14:17:33 +0000 Message-ID: <1268403453.10129.7360.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-03-12 at 14:08 +0000, Stefan Lippers-Hollmann wrote: > Hi > > On Friday 12 March 2010, gregkh@suse.de wrote: > > This is a note to let you know that we have just queued up the patch titled > > > > Subject: x86, xen: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y > > > > to the 2.6.33-stable tree. Its filename is > > > > x86-xen-disable-highmem-pte-allocation-even-when-config_highpte-y.patch > > > > A git repo of this tree can be found at > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > > > From 817a824b75b1475f1b067c8cee318c7b4d66fcde Mon Sep 17 00:00:00 2001 > > From: Ian Campbell > > Date: Fri, 26 Feb 2010 17:16:00 +0000 > > Subject: x86, xen: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y > > MIME-Version: 1.0 > > Content-Type: text/plain; charset=UTF-8 > > Content-Transfer-Encoding: 8bit > > > > From: Ian Campbell > > > > commit 817a824b75b1475f1b067c8cee318c7b4d66fcde upstream. > > > > There's a path in the pagefault code where the kernel deliberately > > breaks its own locking rules by kmapping a high pte page without > > holding the pagetable lock (in at least page_check_address). This > > breaks Xen's ability to track the pinned/unpinned state of the > > page. There does not appear to be a viable workaround for this > > behaviour so simply disable HIGHPTE for all Xen guests. > > This patch breaks compilation of the current 2.6.33 -stable queue and might > also affect queue-2.6.32 (untested): > > CC arch/x86/xen/enlighten.o > arch/x86/xen/enlighten.c: In function ‘xen_start_kernel’: > arch/x86/xen/enlighten.c:1102: error: ‘__userpte_alloc_gfp’ undeclared (first use in this function) > arch/x86/xen/enlighten.c:1102: error: (Each undeclared identifier is reported only once > arch/x86/xen/enlighten.c:1102: error: for each function it appears in.) > make[2]: *** [arch/x86/xen/enlighten.o] Error 1 > make[1]: *** [arch/x86/xen] Error 2 > > as it seems to depend (tested) on: > > commit 14315592009c17035cac81f4954d5a1f4d71e489 > Author: Ian Campbell > Date: Wed Feb 17 10:38:10 2010 +0000 > > x86, mm: Allow highmem user page tables to be disabled at boot time Thanks Stefan, this is indeed the correct fix. I pointed Greg to this patch in private mail this morning. Ian.