On Sat, Oct 07, 2017 at 05:43:32PM +0000, Levin, Alexander (Sasha Levin) wrote:
> On Sat, Oct 07, 2017 at 11:15:17AM +0200, Peter Zijlstra wrote:
> >On Sat, Oct 07, 2017 at 02:07:26AM +0000, Levin, Alexander (Sasha Levin)
> >wrote:
> >> And quite a few lines of your added trace (lmk if you need more, or all):
> >
> >Yeah, could you please upload all of it somewhere? That chunk didn't
> >include any hotplug bits at all.
>
> Attached. It's the stack trace followed by everything else.
Much thanks, clue:
[ 2073.495414] NOHZ: local_softirq_pending 202 -- (TIMER_SOFTIRQ | RCU_SOFTIRQ)
cpuhp/2-22 [002] .... 104.797971: sched_cpu_deactivate: not-active: 2
mask: 0-1,3-4,6-7,9
cpuhp/2-22 [002] .... 104.825166: sched_cpu_deactivate: rcu-sync: 2
migration/2-24 [002] ..s1 104.855994: rebalance_domains: rcu-read-lock: 2
migration/2-24 [002] ..s1 104.856000: load_balance: dst_cpu: 2 cpus: 6
supposed fix; could you please verify?
---
kernel/sched/fair.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 350dbec01523..35f0168fb609 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8392,6 +8392,13 @@ static int should_we_balance(struct lb_env *env)
struct sched_group *sg = env->sd->groups;
int cpu, balance_cpu = -1;
+ /*
+ * Ensure the balancing environment is consistent; can happen
+ * when the softirq triggers 'during' hotplug.
+ */
+ if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
+ return 0;
+
/*
* In the newly idle case, we will allow all the cpu's
* to do the newly idle load balance.
