Merge tag 'usb-serial-4.14-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-bionic-kernel.git] / kernel / sched / fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0a85641e62ce915ff2650c0aee3cdf14a1cc6bd7..70ba32e08a231858326211b7f64a3ae6a3f4dbd3 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8436,6 +8436,12 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
         */
        this_rq->idle_stamp = rq_clock(this_rq);
 
+       /*
+        * Do not pull tasks towards !active CPUs...
+        */
+       if (!cpu_active(this_cpu))
+               return 0;
+
        /*
         * This is OK, because current is on_cpu, which avoids it being picked
         * for load-balance and preemption/IRQs are still disabled avoiding
@@ -8543,6 +8549,13 @@ static int active_load_balance_cpu_stop(void *data)
        struct rq_flags rf;
 
        rq_lock_irq(busiest_rq, &rf);
+       /*
+        * Between queueing the stop-work and running it is a hole in which
+        * CPUs can become inactive. We should not move tasks from or to
+        * inactive CPUs.
+        */
+       if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
+               goto out_unlock;
 
        /* make sure the requested cpu hasn't gone down in the meantime */
        if (unlikely(busiest_cpu != smp_processor_id() ||