From a7c072ef26644b632241d549869f10f8d2dd3b5c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 2 Jul 2020 14:15:33 -0700 Subject: [PATCH] scftorture: Block scftorture_invoker() kthreads for offline CPUs Currently, CPU-hotplug operations might result in all but two of (say) 100 CPUs being offline, which in turn might result in false-positive diagnostics due to overload. This commit therefore causes scftorture_invoker() kthreads for offline CPUs to loop blocking for 200 milliseconds at a time, thus continuously adjusting the number of threads to match the number of online CPUs. Signed-off-by: Paul E. McKenney --- kernel/scftorture.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/scftorture.c b/kernel/scftorture.c index d9c01c7..04d3a42 100644 --- a/kernel/scftorture.c +++ b/kernel/scftorture.c @@ -381,11 +381,14 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra // smp_call_function() family of functions. static int scftorture_invoker(void *arg) { + int cpu; DEFINE_TORTURE_RANDOM(rand); struct scf_statistics *scfp = (struct scf_statistics *)arg; + bool was_offline = false; VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu); - set_cpus_allowed_ptr(current, cpumask_of(scfp->cpu % nr_cpu_ids)); + cpu = scfp->cpu % nr_cpu_ids; + set_cpus_allowed_ptr(current, cpumask_of(cpu)); set_user_nice(current, MAX_NICE); if (holdoff) schedule_timeout_interruptible(holdoff * HZ); @@ -408,6 +411,14 @@ static int scftorture_invoker(void *arg) do { scftorture_invoke_one(scfp, &rand); + while (cpu_is_offline(cpu) && !torture_must_stop()) { + schedule_timeout_interruptible(HZ / 5); + was_offline = true; + } + if (was_offline) { + set_cpus_allowed_ptr(current, cpumask_of(cpu)); + was_offline = false; + } } while (!torture_must_stop()); VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu); -- 2.7.4