3 files changed, 15 insertions, 12 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 11ae2747701b..5797cf2909b0 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1358,10 +1358,11 @@ static void __maybe_unused rcu_advance_cbs_nowake(struct rcu_node *rnp,
 						  struct rcu_data *rdp)
 {
 	rcu_lockdep_assert_cblist_protected(rdp);
-	if (!rcu_seq_state(rcu_seq_current(&rnp->gp_seq)) ||
-	    !raw_spin_trylock_rcu_node(rnp))
+	if (!rcu_seq_state(rcu_seq_current(&rnp->gp_seq)) || !raw_spin_trylock_rcu_node(rnp))
 		return;
-	WARN_ON_ONCE(rcu_advance_cbs(rnp, rdp));
+	// The grace period cannot end while we hold the rcu_node lock.
+	if (rcu_seq_state(rcu_seq_current(&rnp->gp_seq)))
+		WARN_ON_ONCE(rcu_advance_cbs(rnp, rdp));
 	raw_spin_unlock_rcu_node(rnp);
 }
 
@@ -1602,7 +1603,7 @@ static void rcu_gp_fqs(bool first_time)
 	struct rcu_node *rnp = rcu_get_root();
 
 	WRITE_ONCE(rcu_state.gp_activity, jiffies);
-	rcu_state.n_force_qs++;
+	WRITE_ONCE(rcu_state.n_force_qs, rcu_state.n_force_qs + 1);
 	if (first_time) {
 		/* Collect dyntick-idle snapshots. */
 		force_qs_rnp(dyntick_save_progress_counter);
@@ -2207,7 +2208,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
 	/* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
 	if (count == 0 && rdp->qlen_last_fqs_check != 0) {
 		rdp->qlen_last_fqs_check = 0;
-		rdp->n_force_qs_snap = rcu_state.n_force_qs;
+		rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
 	} else if (count < rdp->qlen_last_fqs_check - qhimark)
 		rdp->qlen_last_fqs_check = count;
 
@@ -2535,10 +2536,10 @@ static void __call_rcu_core(struct rcu_data *rdp, struct rcu_head *head,
 		} else {
 			/* Give the grace period a kick. */
 			rdp->blimit = DEFAULT_MAX_RCU_BLIMIT;
-			if (rcu_state.n_force_qs == rdp->n_force_qs_snap &&
+			if (READ_ONCE(rcu_state.n_force_qs) == rdp->n_force_qs_snap &&
 			    rcu_segcblist_first_pend_cb(&rdp->cblist) != head)
 				rcu_force_quiescent_state();
-			rdp->n_force_qs_snap = rcu_state.n_force_qs;
+			rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
 			rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
 		}
 	}
@@ -3029,7 +3030,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
 	/* Set up local state, ensuring consistent view of global state. */
 	raw_spin_lock_irqsave_rcu_node(rnp, flags);
 	rdp->qlen_last_fqs_check = 0;
-	rdp->n_force_qs_snap = rcu_state.n_force_qs;
+	rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
 	rdp->blimit = blimit;
 	if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
 	    !rcu_segcblist_is_offloaded(&rdp->cblist))
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 4c4d7683a4e5..173e3ce60790 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -382,6 +382,7 @@ retry_ipi:
 			continue;
 		}
 		if (get_cpu() == cpu) {
+			mask_ofl_test |= mask;
 			put_cpu();
 			continue;
 		}
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index a71a4a272515..2c127d438fe0 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -523,16 +523,17 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
 			raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 		}
 
-		/* Unboost if we were boosted. */
-		if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
-			rt_mutex_futex_unlock(&rnp->boost_mtx);
-
 		/*
 		 * If this was the last task on the expedited lists,
 		 * then we need to report up the rcu_node hierarchy.
 		 */
 		if (!empty_exp && empty_exp_now)
 			rcu_report_exp_rnp(rnp, true);
+
+		/* Unboost if we were boosted. */
+		if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
+			rt_mutex_futex_unlock(&rnp->boost_mtx);
+
 	} else {
 		local_irq_restore(flags);
 	}