1 files changed, 22 insertions, 12 deletions

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index fb88a028deec..84fbee4686d3 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -180,7 +180,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
 			 (rnp->expmask & rdp->grpmask ? RCU_EXP_BLKD : 0);
 	struct task_struct *t = current;
 
-	lockdep_assert_held(&rnp->lock);
+	raw_lockdep_assert_held_rcu_node(rnp);
 	WARN_ON_ONCE(rdp->mynode != rnp);
 	WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);
 
@@ -560,8 +560,14 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
 	}
 	t = list_entry(rnp->gp_tasks->prev,
 		       struct task_struct, rcu_node_entry);
-	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
+	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) {
+		/*
+		 * We could be printing a lot while holding a spinlock.
+		 * Avoid triggering hard lockup.
+		 */
+		touch_nmi_watchdog();
 		sched_show_task(t);
+	}
 	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 }
 
@@ -957,14 +963,10 @@ static int rcu_boost(struct rcu_node *rnp)
 	 * expedited grace period must boost all blocked tasks, including
 	 * those blocking the pre-existing normal grace period.
 	 */
-	if (rnp->exp_tasks != NULL) {
+	if (rnp->exp_tasks != NULL)
 		tb = rnp->exp_tasks;
-		rnp->n_exp_boosts++;
-	} else {
+	else
 		tb = rnp->boost_tasks;
-		rnp->n_normal_boosts++;
-	}
-	rnp->n_tasks_boosted++;
 
 	/*
 	 * We boost task t by manufacturing an rt_mutex that appears to
@@ -1042,7 +1044,7 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
 {
 	struct task_struct *t;
 
-	lockdep_assert_held(&rnp->lock);
+	raw_lockdep_assert_held_rcu_node(rnp);
 	if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
 		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 		return;
@@ -1677,6 +1679,12 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
 	char *ticks_title;
 	unsigned long ticks_value;
 
+	/*
+	 * We could be printing a lot while holding a spinlock.  Avoid
+	 * triggering hard lockup.
+	 */
+	touch_nmi_watchdog();
+
 	if (rsp->gpnum == rdp->gpnum) {
 		ticks_title = "ticks this GP";
 		ticks_value = rdp->ticks_this_gp;
@@ -2235,7 +2243,6 @@ static int rcu_nocb_kthread(void *arg)
 		smp_mb__before_atomic();  /* _add after CB invocation. */
 		atomic_long_add(-c, &rdp->nocb_q_count);
 		atomic_long_add(-cl, &rdp->nocb_q_count_lazy);
-		rdp->n_nocbs_invoked += c;
 	}
 	return 0;
 }
@@ -2312,8 +2319,11 @@ void __init rcu_init_nohz(void)
 		cpumask_and(rcu_nocb_mask, cpu_possible_mask,
 			    rcu_nocb_mask);
 	}
-	pr_info("\tOffload RCU callbacks from CPUs: %*pbl.\n",
-		cpumask_pr_args(rcu_nocb_mask));
+	if (cpumask_empty(rcu_nocb_mask))
+		pr_info("\tOffload RCU callbacks from CPUs: (none).\n");
+	else
+		pr_info("\tOffload RCU callbacks from CPUs: %*pbl.\n",
+			cpumask_pr_args(rcu_nocb_mask));
 	if (rcu_nocb_poll)
 		pr_info("\tPoll for callbacks from no-CBs CPUs.\n");