From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 18 Oct 2016 16:53:59 +0000 (-0700)
Subject: Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel... 
X-Git-Tag: v4.9-rc2~34
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=2c11fc87caa9a60ada54f4bfc97f7b1abc38d7d0;hp=-c;p=cascardo%2Flinux.git

Merge branch 'sched-urgent-for-linus' of git://git./linux/kernel/git/tip/tip

Pull scheduler fix from Ingo Molnar:
 "Fix a crash that can trigger when racing with CPU hotplug: we didn't
  use sched-domains data structures carefully enough in select_idle_cpu()"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix sched domains NULL dereference in select_idle_sibling()
---

2c11fc87caa9a60ada54f4bfc97f7b1abc38d7d0
diff --combined kernel/sched/fair.c
index 2d4ad72f8f3c,8b03fb5d1b9e..76ee7de1859d
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@@ -5471,13 -5471,18 +5471,18 @@@ static inline int select_idle_smt(struc
   */
  static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target)
  {
- 	struct sched_domain *this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
- 	u64 avg_idle = this_rq()->avg_idle;
- 	u64 avg_cost = this_sd->avg_scan_cost;
+ 	struct sched_domain *this_sd;
+ 	u64 avg_cost, avg_idle = this_rq()->avg_idle;
  	u64 time, cost;
  	s64 delta;
  	int cpu, wrap;
  
+ 	this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
+ 	if (!this_sd)
+ 		return -1;
+ 
+ 	avg_cost = this_sd->avg_scan_cost;
+ 
  	/*
  	 * Due to large variance we need a large fuzz factor; hackbench in
  	 * particularly is sensitive here.
@@@ -8522,7 -8527,7 +8527,7 @@@ static void nohz_idle_balance(struct r
   * run_rebalance_domains is triggered when needed from the scheduler tick.
   * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
   */
 -static void run_rebalance_domains(struct softirq_action *h)
 +static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
  {
  	struct rq *this_rq = this_rq();
  	enum cpu_idle_type idle = this_rq->idle_balance ?