From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761150AbYDBSkA (ORCPT ); Wed, 2 Apr 2008 14:40:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757969AbYDBSfo (ORCPT ); Wed, 2 Apr 2008 14:35:44 -0400 Received: from 21.sub-75-208-3.myvzw.com ([75.208.3.21]:38414 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757305AbYDBSfk (ORCPT ); Wed, 2 Apr 2008 14:35:40 -0400 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [PATCH 21 of 24] xen: allow set_pte_at on init_mm to be lockless X-Mercurial-Node: 3d98a7a43a629aa069cc8391cd93859e0db9d84b Message-Id: <3d98a7a43a629aa069cc.1207158850@localhost> In-Reply-To: Date: Wed, 02 Apr 2008 10:54:10 -0700 From: Jeremy Fitzhardinge To: Ingo Molnar Cc: LKML , Isaku Yamahata Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The usual pagetable locking protocol doesn't seem to apply to updates to init_mm, so don't rely on preemption being disabled in xen_set_pte_at on init_mm. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/mmu.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -156,6 +156,10 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pteval) { + /* updates to init_mm may be done without lock */ + if (mm == &init_mm) + preempt_disable(); + if (mm == current->mm || mm == &init_mm) { if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { struct multicall_space mcs; @@ -163,12 +167,16 @@ MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); xen_mc_issue(PARAVIRT_LAZY_MMU); - return; + goto out; } else if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) - return; + goto out; } xen_set_pte(ptep, pteval); + +out: + if (mm == &init_mm) + preempt_enable(); } pteval_t xen_pte_val(pte_t pte)