From: "Paul E. McKenney" <[email protected]> Because the need to wake a nocb GP kthread ("rcuog") is sometimes detected when wakeups cannot be done, these wakeups can be deferred. The wakeups are then carried out by calls to do_nocb_deferred_wakeup() at various safe points in the code, including RCU's idle hooks. However, when a CPU goes offline, it invokes arch_cpu_idle_dead() without invoking any of RCU's idle hooks.
This commit therefore adds a call to do_nocb_deferred_wakeup() in rcu_report_dead() in order to handle any deferred wakeups that have been requested by the outgoing CPU. Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 03810a5..e6dee71 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4178,6 +4178,9 @@ void rcu_report_dead(unsigned int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ + // Do any dangling deferred wakeups. + do_nocb_deferred_wakeup(rdp); + /* QS for any half-done expedited grace period. */ preempt_disable(); rcu_report_exp_rdp(this_cpu_ptr(&rcu_data)); -- 2.9.5
