From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: patch x86-xen-disable-highmem-pte-allocation-even-when-config_highpte-y.patch added to 2.6.33-stable tree Date: Fri, 12 Mar 2010 08:35:59 -0800 Message-ID: <20100312163559.GA7562@suse.de> References: <12683359492650@site> <201003121508.54384.s.L-H@gmx.de> <1268403453.10129.7360.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1268403453.10129.7360.camel@zakaz.uk.xensource.com> Sender: linux-kernel-owner@vger.kernel.org To: Ian Campbell Cc: Stefan Lippers-Hollmann , "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" List-Id: xen-devel@lists.xenproject.org On Fri, Mar 12, 2010 at 02:17:33PM +0000, Ian Campbell wrote: > On Fri, 2010-03-12 at 14:08 +0000, Stefan Lippers-Hollmann wrote: > > Hi > >=20 > > On Friday 12 March 2010, gregkh@suse.de wrote: > > > This is a note to let you know that we have just queued up the pa= tch titled > > >=20 > > > Subject: x86, xen: Disable highmem PTE allocation even when C= ONFIG_HIGHPTE=3Dy > > >=20 > > > to the 2.6.33-stable tree. Its filename is > > >=20 > > > x86-xen-disable-highmem-pte-allocation-even-when-config_highp= te-y.patch > > >=20 > > > A git repo of this tree can be found at=20 > > > http://www.kernel.org/git/?p=3Dlinux/kernel/git/stable/stable= -queue.git;a=3Dsummary > > >=20 > > >=20 > > > 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 CONFI= G_HIGHPTE=3Dy > > > MIME-Version: 1.0 > > > Content-Type: text/plain; charset=3DUTF-8 > > > Content-Transfer-Encoding: 8bit > > >=20 > > > From: Ian Campbell > > >=20 > > > commit 817a824b75b1475f1b067c8cee318c7b4d66fcde upstream. > > >=20 > > > There's a path in the pagefault code where the kernel deliberatel= y > > > 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. > >=20 > > This patch breaks compilation of the current 2.6.33 -stable queue a= nd might > > also affect queue-2.6.32 (untested): > >=20 > > CC arch/x86/xen/enlighten.o > > arch/x86/xen/enlighten.c: In function =E2=80=98xen_start_kernel=E2=80= =99: > > arch/x86/xen/enlighten.c:1102: error: =E2=80=98__userpte_alloc_gfp=E2= =80=99 undeclared (first use in this function) > > arch/x86/xen/enlighten.c:1102: error: (Each undeclared identifier i= s 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 > >=20 > > as it seems to depend (tested) on: > >=20 > > commit 14315592009c17035cac81f4954d5a1f4d71e489 > > Author: Ian Campbell > > Date: Wed Feb 17 10:38:10 2010 +0000 > >=20 > > x86, mm: Allow highmem user page tables to be disabled at boot = time >=20 > Thanks Stefan, this is indeed the correct fix. I pointed Greg to this > patch in private mail this morning. I've just added it. Odd that the kernel doesn't fail on my builds. Oh= , I'm not enabling Xen, that's why, my fault... thanks, greg k-h