From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934883AbaGXXhZ (ORCPT ); Thu, 24 Jul 2014 19:37:25 -0400 Received: from terminus.zytor.com ([198.137.202.10]:34868 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932131AbaGXXhX (ORCPT ); Thu, 24 Jul 2014 19:37:23 -0400 Date: Thu, 24 Jul 2014 16:36:33 -0700 From: tip-bot for Borislav Petkov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, boris.ostrovsky@oracle.com, tglx@linutronix.de, bp@suse.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, tglx@linutronix.de, bp@suse.de In-Reply-To: <1403274493-1371-1-git-send-email-boris.ostrovsky@oracle.com> References: <1403274493-1371-1-git-send-email-boris.ostrovsky@oracle.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, MCE: Robustify mcheck_init_device Git-Commit-ID: 51cbe7e7c400def749950ab6b2c120624dbe21a7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 51cbe7e7c400def749950ab6b2c120624dbe21a7 Gitweb: http://git.kernel.org/tip/51cbe7e7c400def749950ab6b2c120624dbe21a7 Author: Borislav Petkov AuthorDate: Fri, 20 Jun 2014 23:16:45 +0200 Committer: Borislav Petkov CommitDate: Mon, 21 Jul 2014 18:14:32 +0200 x86, MCE: Robustify mcheck_init_device BorisO reports that misc_register() fails often on xen. The current code unregisters the CPU hotplug notifier in that case. If then a CPU is offlined and onlined back again, we end up with a second timer running on that CPU, leading to soft lockups and system hangs. So let's leave the hotcpu notifier always registered - even if mce_device_create failed for some cores and never unreg it so that we can deal with the timer handling accordingly. Reported-and-Tested-by: Boris Ostrovsky Link: http://lkml.kernel.org/r/1403274493-1371-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/mcheck/mce.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index bb92f38..9a79c8d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -2451,6 +2451,12 @@ static __init int mcheck_init_device(void) for_each_online_cpu(i) { err = mce_device_create(i); if (err) { + /* + * Register notifier anyway (and do not unreg it) so + * that we don't leave undeleted timers, see notifier + * callback above. + */ + __register_hotcpu_notifier(&mce_cpu_notifier); cpu_notifier_register_done(); goto err_device_create; } @@ -2471,10 +2477,6 @@ static __init int mcheck_init_device(void) err_register: unregister_syscore_ops(&mce_syscore_ops); - cpu_notifier_register_begin(); - __unregister_hotcpu_notifier(&mce_cpu_notifier); - cpu_notifier_register_done(); - err_device_create: /* * We didn't keep track of which devices were created above, but