diff options
| author | Peter Zijlstra | 2013-11-06 18:47:57 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2013-11-13 13:33:52 +0100 |
| commit | 5eca82a9ac2c961cfbd26a4b6f43e6e3747a71dd (patch) | |
| tree | c63a3495a562c32b447bd4dec093eca98e9a584b | |
| parent | 46a73e8a1c1720f7713b5e2df68e9dd272015b5d (diff) | |
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: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: http://lkml.kernel.org/n/tip-orja0qylcvyhxfsuebcyL5sI@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/sched/fair.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c11e36ff5ea0..201be782b5b3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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); |