From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933617AbXCZG2N (ORCPT ); Mon, 26 Mar 2007 02:28:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933612AbXCZG2N (ORCPT ); Mon, 26 Mar 2007 02:28:13 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:4792 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933626AbXCZG2M (ORCPT ); Mon, 26 Mar 2007 02:28:12 -0400 X-AuditID: d80ac287-94e6abb000000c42-45-460767c61b2d Date: Mon, 26 Mar 2007 07:27:07 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Zachary Amsden cc: David Rientjes , Andrew Morton , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young} In-Reply-To: <4607713F.6010900@vmware.com> Message-ID: References: <4607713F.6010900@vmware.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 26 Mar 2007 06:27:18.0107 (UTC) FILETIME=[CD60BAB0:01C76F6F] X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 25 Mar 2007, Zachary Amsden wrote: > > If you actually clear the bit, you need to: > > + pte_update_defer(vma->vm_mm, addr, ptep); > > The reason is, when updating PTEs, the hypervisor must be notified. Using > atomic operations to do this is fine for all hypervisors I am aware of. > However, for hypervisors which shadow page tables, if these PTE modifications > are not trapped, you need a post-modification call to fulfill the update of > the shadow page table. Thanks for the very rapid response. So, David just needs to move the pte_update_defer out of ptep_clear_flush_* and into ptep_test_and_clear_*? That leaves me wondering why you deleted ptep_test_and_clear_* (while leaving their __HAVE_ARCHes) in the first place? Hugh