From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762785AbYDURgQ (ORCPT ); Mon, 21 Apr 2008 13:36:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753708AbYDURgD (ORCPT ); Mon, 21 Apr 2008 13:36:03 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56131 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753423AbYDURgB (ORCPT ); Mon, 21 Apr 2008 13:36:01 -0400 Message-ID: <480CCEB0.8040401@zytor.com> Date: Mon, 21 Apr 2008 13:28:16 -0400 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Pavel Machek CC: Mathieu Desnoyers , mingo@elte.hu, akpm@osdl.org, Jeremy Fitzhardinge , Steven Rostedt , "Frank Ch. Eigler" , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5) References: <20080417165839.GA25198@Krystal> <20080417165944.GB25198@Krystal> <20080417201410.GB31616@Krystal> <20080421140054.GB4685@ucw.cz> <480CA337.3090709@zytor.com> <20080421150825.GA4070@Krystal> <480CADD3.3010209@zytor.com> <20080421154756.GA2424@Krystal> <20080421172327.GA32278@elf.ucw.cz> In-Reply-To: <20080421172327.GA32278@elf.ucw.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek wrote: > >> There is also the page fault case. I think putting this test in >> ret_from_exception would be both safe (it is executed for any >> exception return) and fast (exceptions are rare). > > Eh? I thought that page fault is one of the hottest paths in kernel > (along with syscall and packet receive/send)... > Pavel Yeah, and the concept of handling page faults inside an NMI handler is pure fantasy. -hpa