Hi Paul. > Suppose that the scheduler-clock interrupt invoking rcu_sched_clock_irq() > happened just before the lock was acquired in rcu_report_qs_rdp(). > Suppose further that the RCU grace-period kthread started a new grace > period just before that interrupt occurred. Then mightn't that interrupt > notice the new grace period and set ->cpu_no_qs.b.norm to true before > fully returning? IIUC, RCU grace-period kthread couldn't start new grace period because the interrupted cpu don't report qs to rnp via rcu_report_qs_rdp. That situation is listened like new gp could be started thou all cpus doesn't enter yet. That's is the reason why it's better to use WARN_ON_ONCE as you suggest to notice if the buggy situation happens Am I missing something or wrong? Thanks. -------- Sincerely, Levi.
