From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753947Ab2HVUPF (ORCPT ); Wed, 22 Aug 2012 16:15:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32709 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428Ab2HVUPD (ORCPT ); Wed, 22 Aug 2012 16:15:03 -0400 Date: Wed, 22 Aug 2012 22:14:55 +0200 From: Andrea Arcangeli To: Andrew Morton Cc: Xiao Guangrong , Avi Kivity , Marcelo Tosatti , LKML , KVM , Linux Memory Management List Subject: Re: [PATCH] mm: mmu_notifier: fix inconsistent memory between secondary MMU and host Message-ID: <20120822201455.GB8107@redhat.com> References: <503358FF.3030009@linux.vnet.ibm.com> <20120821150618.GJ27696@redhat.com> <5034763D.60508@linux.vnet.ibm.com> <20120822162955.GT29978@redhat.com> <20120822121535.8be38858.akpm@linux-foundation.org> <20120822195043.GA8107@redhat.com> <20120822125805.9c62aa79.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120822125805.9c62aa79.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 22, 2012 at 12:58:05PM -0700, Andrew Morton wrote: > If you can suggest some text I'll type it in right now. Ok ;), I tried below: This is safe to start by updating the secondary MMUs, because the relevant primary MMU pte invalidate must have already happened with a ptep_clear_flush before set_pte_at_notify has been invoked. Updating the secondary MMUs first is required when we change both the protection of the mapping from read-only to read-write and the pfn (like during copy on write page faults). Otherwise the old page would remain mapped readonly in the secondary MMUs after the new page is already writable by some CPU through the primary MMU." Thanks! Andrea