[PATCH] sched/numa: fix choosing isolated CPUs when task_numa_migrate()

[Yi Wang]

When trying to migrate to a CPU in task_numa_migrate(), we invoke
task_numa_find_cpu() to choose a spot, in which function we skip
the CPU which is not in cpus_allowed, but forgot to concern the
isolated CPUs, and this may cause the task would run on the isolcpus.

This patch fixes this issue by checking the load_balance_mask.

Signed-off-by: Yi Wang <wang.yi59@xxxxxxxxxx>
Reviewed-by: Yi Liu <liu.yi24@xxxxxxxxxx>
---
 kernel/sched/fair.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 908c9cd..0fa0cee 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1709,6 +1709,7 @@ static void task_numa_compare(struct task_numa_env *env,
 	rcu_read_unlock();
 }
 
+static int is_cpu_load_balance(int cpu);
 static void task_numa_find_cpu(struct task_numa_env *env,
 				long taskimp, long groupimp)
 {
@@ -1731,6 +1732,9 @@ static void task_numa_find_cpu(struct task_numa_env *env,
 		if (!cpumask_test_cpu(cpu, &env->p->cpus_allowed))
 			continue;
 
+		if (!is_cpu_load_balance(cpu))
+			continue;
+
 		env->dst_cpu = cpu;
 		task_numa_compare(env, taskimp, groupimp, maymove);
 	}
@@ -8528,6 +8532,12 @@ static int should_we_balance(struct lb_env *env)
 	return balance_cpu == env->dst_cpu;
 }
 
+static int is_cpu_load_balance(int cpu)
+{
+	struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
+
+	return cpumask_test_cpu(cpu, cpus);
+}
+
 /*
  * Check this_cpu to ensure it is balanced within domain. Attempt to move
  * tasks if there is an imbalance.
-- 
1.8.3.1