Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5eca82a9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/numa: Cure update_numa_stats() vs. hotplug 



Because we're completely unserialized against hotplug its well
possible to try and generate numa stats for an offlined node.

Bail out early (and avoid a /0) in this case. The resulting stats are
all 0 which should result in an undesirable balance target -- not to
mention that actually trying to migrate to an offline CPU will fail.

Reported-by: default avatarPrarit Bhargava <prarit@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: http://lkml.kernel.org/n/tip-orja0qylcvyhxfsuebcyL5sI@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 46a73e8a

kernel/sched/fair.c

+14 −1
Original line number Diff line number Diff line
@@ -1000,7 +1000,7 @@ struct numa_stats { 
 */

static void update_numa_stats(struct numa_stats *ns, int nid)

{

	int cpu;

	int cpu, cpus = 0;



	memset(ns, 0, sizeof(*ns));

	for_each_cpu(cpu, cpumask_of_node(nid)) {
@@ -1009,8 +1009,21 @@ static void update_numa_stats(struct numa_stats *ns, int nid) 
		ns->nr_running += rq->nr_running;

		ns->load += weighted_cpuload(cpu);

		ns->power += power_of(cpu);



		cpus++;

	}



	/*

	 * If we raced with hotplug and there are no CPUs left in our mask

	 * the @ns structure is NULL'ed and task_numa_compare() will

	 * not find this node attractive.

	 *

	 * We'll either bail at !has_capacity, or we'll detect a huge imbalance

	 * and bail there.

	 */

	if (!cpus)

		return;



	ns->load = (ns->load * SCHED_POWER_SCALE) / ns->power;

	ns->capacity = DIV_ROUND_CLOSEST(ns->power, SCHED_POWER_SCALE);

	ns->has_capacity = (ns->nr_running < ns->capacity);