From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752912AbcCKWeB (ORCPT ); Fri, 11 Mar 2016 17:34:01 -0500 Received: from mga04.intel.com ([192.55.52.120]:4254 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752622AbcCKWd7 (ORCPT ); Fri, 11 Mar 2016 17:33:59 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,321,1455004800"; d="scan'208";a="932052404" Date: Fri, 11 Mar 2016 14:33:57 -0800 From: "Luck, Tony" To: Thomas Gleixner Cc: LKML , Harry Junior , x86@kernel.org, Peter Zijlstra , Joe Lawrence , Borislav Petkov Subject: Re: [PATCH] x86/irq: Cure live lock in irq_force_complete_move() Message-ID: <20160311223357.GA2544@intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With this patch applied my system survives me doing several rounds of: # echo 0 | tee /sys/devices/system/cpu/cpu*/online # echo 1 | tee /sys/devices/system/cpu/cpu*/online whereas without the patch the first of those went to [152455.129604] NMI watchdog: Watchdog detected hard LOCKUP on cpu 96 [152455.136943] Kernel panic - not syncing: Hard LOCKUP I'm not sure we care to optimize the cpu offline path, but I'll note here that taking all (but one) cpus offline took 52 seconds (for a hundred and mumble logical cpus). Bringing them all back is just 4 seconds. Tested-by: Tony Luck