From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755975Ab1BCEXW (ORCPT ); Wed, 2 Feb 2011 23:23:22 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53528 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755704Ab1BCEXW (ORCPT ); Wed, 2 Feb 2011 23:23:22 -0500 Message-ID: <4D4A2D9C.2040803@zytor.com> Date: Wed, 02 Feb 2011 20:22:52 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc14 Thunderbird/3.1.7 MIME-Version: 1.0 To: Linus Torvalds CC: Andi Kleen , Suresh Siddha , Ingo Molnar , Thomas Gleixner , LKML , "Mallick, Asit K" Subject: Re: [patch] x86, mm: avoid stale tlb entries by clearing prev mm_cpumask after switching mm References: <1296677247.4418.103.camel@sbsiddha-MOBL3.sc.intel.com> <1296698151.4418.464.camel@sbsiddha-MOBL3.sc.intel.com> <20110203021510.GM15569@one.firstfloor.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/02/2011 08:12 PM, Linus Torvalds wrote: > > So right now, we pretty much depend on "asm volatile" (a) not being > re-ordered wrt other asm volatiles and (b) having that dependency on > memory. > > Iirc, the gcc people even agreed on this. Peter may remember details better.. > Yes, IIRC an "asm volatile" is assumed to be a universal consumer of memory (it is only a universal producer if the "memory" clobber is used), as well as being ordered with respect to other volatile operations. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.