In the case of an affinity change during a migrate_disable section,
__set_cpus_allowed_ptr will not try to move the task from a CPU
in which it cannot execute anymore.
So, after enabling migration, if the current task cannot execute in
the current CPU anymore, migrate it away.
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Luis Claudio R. Goncalves <lgoncalv@xxxxxxxxxx>
Cc: Clark Williams <williams@xxxxxxxxxx>
Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Cc: linux-rt-users <linux-rt-users@xxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0396bf2..207bc85 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3462,6 +3462,34 @@ void migrate_enable(void)
task_rq(p)->dl.dl_nr_migratory++;
}
+ /*
+ * Check if the task can still run on this CPU. In the case of an
+ * affinity change during a migrate_disable section,
+ * __set_cpus_allowed_ptr will not try to move the task from a CPU
+ * that the task cannot execute anymore.
+ *
+ * So, if the current task cannot execute in the current CPU anymore,
+ * migrate it away.
+ */
+ if (unlikely(!cpumask_test_cpu(task_cpu(p), &p->cpus_allowed))) {
+ const struct cpumask *cpu_mask = (p->flags & PF_KTHREAD) ?
+ cpu_online_mask : cpu_active_mask;
+
+ int dest_cpu = cpumask_any_and(cpu_mask, &p->cpus_allowed);
+ struct migration_arg arg = {p, dest_cpu};
+
+ /* Need help from migration thread: drop lock and wait. */
+ task_rq_unlock(rq, p, &rf);
+ unpin_current_cpu();
+ preempt_enable();
+ preempt_lazy_enable();
+
+ stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
+ tlb_migrate_finish(p->mm);
+
+ return;
+ }
+
task_rq_unlock(rq, p, &rf);
unpin_current_cpu();
preempt_enable();
--
2.9.4
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
