From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hpa@zytor.com, linux-kernel@vger.kernel.org,
peterz@infradead.org, tglx@linutronix.de, mingo@kernel.org,
paulmck@linux.vnet.ibm.com
Subject: [tip:smp/hotplug] cpu/hotplug: Plug death reporting race
Date: Thu, 3 Mar 2016 02:03:35 -0800 [thread overview]
Message-ID: <tip-71f87b2fc64c2e9b6d53cb817f28711b959d3dfe@git.kernel.org> (raw)
In-Reply-To: <20160302201127.GA23440@linux.vnet.ibm.com>
Commit-ID: 71f87b2fc64c2e9b6d53cb817f28711b959d3dfe
Gitweb: http://git.kernel.org/tip/71f87b2fc64c2e9b6d53cb817f28711b959d3dfe
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 3 Mar 2016 10:52:10 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 3 Mar 2016 10:52:10 +0100
cpu/hotplug: Plug death reporting race
Paul noticed that the conversion of the death reporting introduced a race
where the outgoing cpu might be delayed after waking the controll processor,
so it might not be able to call rcu_report_dead() before being physically
removed, leading to RCU stalls.
We cant call complete after rcu_report_dead(), so instead of going back to
busy polling, simply issue a function call to do the completion.
Fixes: 27d50c7eeb0f "rcu: Make CPU_DYING_IDLE an explicit call"
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20160302201127.GA23440@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
---
kernel/cpu.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index ff8059b..93e9d89 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -755,14 +755,26 @@ static int notify_dead(unsigned int cpu)
return 0;
}
+static void cpuhp_complete_idle_dead(void *arg)
+{
+ struct cpuhp_cpu_state *st = arg;
+
+ complete(&st->done);
+}
+
void cpuhp_report_idle_dead(void)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
BUG_ON(st->state != CPUHP_AP_OFFLINE);
- st->state = CPUHP_AP_IDLE_DEAD;
- complete(&st->done);
rcu_report_dead(smp_processor_id());
+ st->state = CPUHP_AP_IDLE_DEAD;
+ /*
+ * We cannot call complete after rcu_report_dead() so we delegate it
+ * to an online cpu.
+ */
+ smp_call_function_single(cpumask_first(cpu_online_mask),
+ cpuhp_complete_idle_dead, st, 0);
}
#else
next prev parent reply other threads:[~2016-03-03 10:04 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-26 18:43 [patch 00/20] cpu/hotplug: Core infrastructure for cpu hotplug rework Thomas Gleixner
2016-02-26 18:43 ` [patch 01/20] idle: Move x86ism out of generic code Thomas Gleixner
2016-02-27 20:29 ` Brian Gerst
2016-02-29 19:35 ` Thomas Gleixner
2016-02-29 19:48 ` Will Deacon
2016-02-29 20:06 ` Thomas Gleixner
2016-02-26 18:43 ` [patch 02/20] cpu/hotplug: Restructure FROZEN state handling Thomas Gleixner
2016-03-01 19:51 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:35 ` Srivatsa S. Bhat
2016-03-02 23:43 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 03/20] cpu/hotplug: Restructure cpu_up code Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:36 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 04/20] cpu/hotplug: Split out cpu down functions Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:37 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 05/20] cpu/hotplug: Add tracepoints Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 06/20] cpu/hotplug: Convert to a state machine for the control processor Thomas Gleixner
2016-03-01 19:53 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 11:23 ` Peter Zijlstra
2016-02-26 18:43 ` [patch 07/20] cpu/hotplug: Convert the hotplugged cpu work to a state machine Thomas Gleixner
2016-03-01 19:53 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 08/20] cpu/hotplug: Hand in target state to _cpu_up/down Thomas Gleixner
2016-03-01 19:54 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 09/20] cpu/hotplug: Add sysfs state interface Thomas Gleixner
2016-03-01 19:54 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 12:40 ` Peter Zijlstra
2016-02-26 18:43 ` [patch 10/20] cpu/hotplug: Make target state writeable Thomas Gleixner
2016-02-26 23:46 ` Rafael J. Wysocki
2016-02-27 7:39 ` Thomas Gleixner
2016-02-27 14:43 ` Rafael J. Wysocki
2016-02-28 14:49 ` Thomas Gleixner
2016-02-29 15:49 ` Thomas Gleixner
2016-03-01 1:53 ` Rafael J. Wysocki
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 12:41 ` Peter Zijlstra
2016-03-02 19:57 ` Thomas Gleixner
2016-02-26 18:43 ` [patch 11/20] cpu/hotplug: Implement setup/removal interface Thomas Gleixner
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 12/20] cpu/hotplug: Move scheduler cpu_online notifier to hotplug core Thomas Gleixner
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 13/20] cpu/hotplug: Unpark smpboot threads from the state machine Thomas Gleixner
2016-03-01 19:56 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 14/20] cpu/hotplug: Split out the state walk into functions Thomas Gleixner
2016-03-01 19:56 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 15/20] cpu/hotplug: Create hotplug threads Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 16/20] cpu/hotplug: Move online calls to hotplugged cpu Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 17/20] arch/hotplug: Call into idle with a proper state Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 18/20] cpu/hotplug: Let upcoming cpu bring itself fully up Thomas Gleixner
2016-03-01 19:58 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 17:28 ` [patch 18/20] " Richard Cochran
2016-02-26 18:43 ` [patch 19/20] cpu/hotplug: Make wait for dead cpu completion based Thomas Gleixner
2016-03-01 19:58 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 20/20] rcu: Make CPU_DYING_IDLE an explicit call Thomas Gleixner
2016-02-27 2:14 ` Paul E. McKenney
2016-02-27 2:23 ` Paul E. McKenney
2016-02-27 7:47 ` Thomas Gleixner
2016-02-27 11:05 ` Paul E. McKenney
2016-02-27 11:30 ` Thomas Gleixner
2016-02-27 16:33 ` Paul E. McKenney
2016-03-01 19:58 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 20:11 ` Paul E. McKenney
2016-03-03 7:31 ` Thomas Gleixner
2016-03-03 10:03 ` tip-bot for Thomas Gleixner [this message]
2016-03-03 14:11 ` [tip:smp/hotplug] cpu/hotplug: Plug death reporting race Paul E. McKenney
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