From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753475AbdIDJXF (ORCPT ); Mon, 4 Sep 2017 05:23:05 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:41505 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753359AbdIDJXE (ORCPT ); Mon, 4 Sep 2017 05:23:04 -0400 Date: Mon, 4 Sep 2017 11:23:01 +0200 (CEST) From: Thomas Gleixner To: "Huang, Ying" cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] IRQ, cpu-hotplug: Fix a race between CPU hotplug and IRQ desc alloc/free In-Reply-To: <20170904085308.17637-1-ying.huang@intel.com> Message-ID: References: <20170904085308.17637-1-ying.huang@intel.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) 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 On Mon, 4 Sep 2017, Huang, Ying wrote: > diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c > index 638eb9c83d9f..af9029625271 100644 > --- a/kernel/irq/cpuhotplug.c ry> +++ b/kernel/irq/cpuhotplug.c > @@ -129,10 +129,13 @@ void irq_migrate_all_off_this_cpu(void) > struct irq_desc *desc; > unsigned int irq; > > + irq_lock_sparse(); You cannot take that lock here as irq_migrate_all_off_this_cpu() is called with interrupts disabled. The protection in takedown_cpus() is wrong. Patch below. Thanks, tglx ---- --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -642,13 +642,13 @@ static int takedown_cpu(unsigned int cpu wait_for_completion(&st->done); BUG_ON(st->state != CPUHP_AP_IDLE_DEAD); - /* Interrupts are moved away from the dying cpu, reenable alloc/free */ - irq_unlock_sparse(); - hotplug_cpu__broadcast_tick_pull(cpu); /* This actually kills the CPU. */ __cpu_die(cpu); + /* Interrupts are moved away from the dying cpu, reenable alloc/free */ + irq_unlock_sparse(); + tick_cleanup_dead_cpu(cpu); return 0; }