From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756583Ab1K2UJv (ORCPT ); Tue, 29 Nov 2011 15:09:51 -0500 Received: from mga14.intel.com ([143.182.124.37]:8945 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756260Ab1K2UJt (ORCPT ); Tue, 29 Nov 2011 15:09:49 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.69,592,1315206000"; d="scan'208";a="42226817" From: Andi Kleen To: Linus Torvalds Cc: Steven Rostedt , LKML , Ingo Molnar , Peter Zijlstra , "H. Peter Anvin" , Frederic Weisbecker , Thomas Gleixner , Mathieu Desnoyers , Paul Turner Subject: Re: Perhaps a side effect regarding NMI returns References: <1322539673.17003.45.camel@frodo> Date: Tue, 29 Nov 2011 12:09:47 -0800 In-Reply-To: (Linus Torvalds's message of "Mon, 28 Nov 2011 20:53:55 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: Not sure what problem Steven thinks is there. Once you switched the stack any nesting is fine. > I would suggest that the actual NMI handler itself should probably > never use that paranoid exit at all, and just always use a regular > iret. Screw scheduling and TIF checks. The reason I added them originally is to prevent the race of remote kernel events being delayed for a long time. With Frederic's nohz work this will be more important in the future. Today it would be eventually picked up by the regular timer interrupts. -Andi -- ak@linux.intel.com -- Speaking for myself only