From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933875AbdIYIzR (ORCPT ); Mon, 25 Sep 2017 04:55:17 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:57691 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932395AbdIYIzQ (ORCPT ); Mon, 25 Sep 2017 04:55:16 -0400 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Mon, 25 Sep 2017 17:54:59 +0900 From: Byungchul Park To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, rostedt@goodmis.org, bigeasy@linutronix.de, efault@gmx.de, max.byungchul.park@gmail.com, kernel-team@lge.com Subject: Re: [PATCH 6/7] smp/hotplug: Differentiate the AP-work lockdep class between up and down Message-ID: <20170925085459.GK5994@X58A-UD3R> References: <20170920170014.548896195@infradead.org> <20170920170546.922524234@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170920170546.922524234@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 20, 2017 at 07:00:20PM +0200, Peter Zijlstra wrote: > With lockdep-crossrelease we get deadlock reports that span cpu-up and > cpu-down chains. Such deadlocks cannot possibly happen because cpu-up > and cpu-down are globally serialized. > > CPU0 CPU1 CPU2 > cpuhp_up_callbacks: takedown_cpu: cpuhp_thread_fun: > > cpuhp_state > irq_lock_sparse() > irq_lock_sparse() > wait_for_completion() > cpuhp_state > complete() > > Now that we have consistent AP state, we can trivially separate the > AP-work class between up and down using st->bringup. Could you tell me what branch you worked the patches based on? This is similar to the problem of workqueue so I want to fix it on top of yours, as well. > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/cpu.c | 41 ++++++++++++++++++++++++++++++++--------- > 1 file changed, 32 insertions(+), 9 deletions(-) > > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -68,9 +68,26 @@ struct cpuhp_cpu_state { > static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); > > #if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP) > -static struct lock_class_key cpuhp_state_key; > -static struct lockdep_map cpuhp_state_lock_map = > - STATIC_LOCKDEP_MAP_INIT("cpuhp_state", &cpuhp_state_key); > +static struct lockdep_map cpuhp_state_up_map = > + STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map); > +static struct lockdep_map cpuhp_state_down_map = > + STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map); > + > + > +static void inline cpuhp_lock_acquire(bool bringup) > +{ > + lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); > +} > + > +static void inline cpuhp_lock_release(bool bringup) > +{ > + lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); > +} > +#else > + > +static void inline cpuhp_lock_acquire(bool bringup) { } > +static void inline cpuhp_lock_release(bool bringup) { } > + > #endif > > /** > @@ -512,7 +529,7 @@ static void cpuhp_thread_fun(unsigned in > if (WARN_ON_ONCE(!st->should_run)) > return; > > - lock_map_acquire(&cpuhp_state_lock_map); > + cpuhp_lock_acquire(bringup); > > if (st->single) { > state = st->cb_state; > @@ -564,7 +581,7 @@ static void cpuhp_thread_fun(unsigned in > } > > next: > - lock_map_release(&cpuhp_state_lock_map); > + cpuhp_lock_release(bringup); > > if (!st->should_run) > complete(&st->done); > @@ -581,8 +598,11 @@ cpuhp_invoke_ap_callback(int cpu, enum c > if (!cpu_online(cpu)) > return 0; > > - lock_map_acquire(&cpuhp_state_lock_map); > - lock_map_release(&cpuhp_state_lock_map); > + cpuhp_lock_acquire(false); > + cpuhp_lock_release(false); > + > + cpuhp_lock_acquire(true); > + cpuhp_lock_release(true); > > /* > * If we are up and running, use the hotplug thread. For early calls > @@ -620,8 +640,11 @@ static int cpuhp_kick_ap_work(unsigned i > enum cpuhp_state prev_state = st->state; > int ret; > > - lock_map_acquire(&cpuhp_state_lock_map); > - lock_map_release(&cpuhp_state_lock_map); > + cpuhp_lock_acquire(false); > + cpuhp_lock_release(false); > + > + cpuhp_lock_acquire(true); > + cpuhp_lock_release(true); > > trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work); > ret = cpuhp_kick_ap(st, st->target); >