KTHREAD_IS_PER_CPU
clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
set_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))