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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-18 09:53:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-18 09:53:59 -0700
commit2c11fc87caa9a60ada54f4bfc97f7b1abc38d7d0 (patch)
tree50a0899747507dd45861687cc58793ecc40d3734 /kernel
parentb75d3886f34e194780239231aa973b283afa9a3a (diff)
parent9cfb38a7ba5a9c27c1af8093fb1af4b699c0a441 (diff)
downloadlinux-2c11fc87caa9a60ada54f4bfc97f7b1abc38d7d0.tar.gz
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/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()
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2d4ad72f8f3c..76ee7de1859d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5471,13 +5471,18 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd
  */
 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.