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()
*/
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.