From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936339Ab0CMBQc (ORCPT ); Fri, 12 Mar 2010 20:16:32 -0500 Received: from kroah.org ([198.145.64.141]:60969 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935006Ab0CMAUt (ORCPT ); Fri, 12 Mar 2010 19:20:49 -0500 X-Mailbox-Line: From gregkh@kvm.kroah.org Fri Mar 12 16:15:13 2010 Message-Id: <20100313001513.015536228@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Fri, 12 Mar 2010 16:13:08 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ian Campbell , Jeremy Fitzhardinge , Ingo Molnar , =?UTF-8?q?Pasi=20K=C3=A4rkk=C3=A4inen?= , , "H. Peter Anvin" Subject: [patch 090/123] x86, xen: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y In-Reply-To: <20100313001618.GA9811@kroah.com> In-Reply-To: <20100313001618.GA9811@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let me know. ----------------- 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. Signed-off-by: Ian Campbell LKML-Reference: <1267204562-11844-1-git-send-email-ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge Cc: Ingo Molnar Cc: Pasi Kärkkäinen Cc: Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/enlighten.c | 7 +++++++ arch/x86/xen/mmu.c | 11 ++++++----- 2 files changed, 13 insertions(+), 5 deletions(-) --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -50,6 +50,7 @@ #include #include #include +#include #include #include #include @@ -1094,6 +1095,12 @@ asmlinkage void __init xen_start_kernel( __supported_pte_mask |= _PAGE_IOMAP; + /* + * Prevent page tables from being allocated in highmem, even + * if CONFIG_HIGHPTE is enabled. + */ + __userpte_alloc_gfp &= ~__GFP_HIGHMEM; + /* Work out if we support NX */ x86_configure_nx(); --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1432,14 +1432,15 @@ static void *xen_kmap_atomic_pte(struct { pgprot_t prot = PAGE_KERNEL; + /* + * We disable highmem allocations for page tables so we should never + * see any calls to kmap_atomic_pte on a highmem page. + */ + BUG_ON(PageHighMem(page)); + if (PagePinned(page)) prot = PAGE_KERNEL_RO; - if (0 && PageHighMem(page)) - printk("mapping highpte %lx type %d prot %s\n", - page_to_pfn(page), type, - (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" : "READ"); - return kmap_atomic_prot(page, type, prot); } #endif