From: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx> As idle tasks cannot be non-voluntary preempted, idle tasks which are not running on CPU are not in RCU-tasks read side critical section. So, remove them for holdout tasks for RCU-tasks. Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx> --- kernel/rcu/tasks.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index b794deeaf6d8..9523aff6cdae 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -983,6 +983,15 @@ static bool rcu_idle_task_is_holdout(struct task_struct *t, int cpu) if (!rcu_cpu_online(cpu)) return false; + /* + * As idle tasks cannot be involuntary preempted, non-running idle tasks + * are not in RCU-tasks critical section. + * synchronize_rcu() calls in rcu_tasks_pregp_step() and rcu_tasks_postgp() + * ensure that all ->on_cpu transitions are complete. + */ + if (!t->on_cpu) + return false; + return true; } #else /* #ifdef CONFIG_SMP */ -- 2.40.1
