The checklist.rst document advises periodic synchronize_rcu() invocations
to prevent callback flooding.  However, rcu_barrier() is often a better
choice.  This commit therefore adds words to this effect.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 Documentation/RCU/checklist.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst
index 2db206fc3465f..178ca7547b987 100644
--- a/Documentation/RCU/checklist.rst
+++ b/Documentation/RCU/checklist.rst
@@ -305,7 +305,8 @@ over a rather long period of time, but improvements are always welcome!
 		the machine.
 
 	d.	Periodically invoke synchronize_rcu(), permitting a limited
-		number of updates per grace period.
+		number of updates per grace period.  Better yet, periodically
+		invoke rcu_barrier() to wait for all outstanding callbacks.
 
 	The same cautions apply to call_srcu() and kfree_rcu().
 
-- 
2.31.1.189.g2e36527f23