Merge branch 'origin'

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index e118a7c1a092..49e27cc19385 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -177,3 +177,9 @@ over a rather long period of time, but improvements are always welcome!
 
         If you want to wait for some of these other things, you might
         instead need to use synchronize_irq() or synchronize_sched().
+
+12.     Any lock acquired by an RCU callback must be acquired elsewhere
+        with irq disabled, e.g., via spin_lock_irqsave().  Failing to
+        disable irq on a given acquisition of that lock will result in
+        deadlock as soon as the RCU callback happens to interrupt that
+        acquisition's critical section.