From: "Paul E. McKenney" <paul...@kernel.org>
Currently, stallwarn.rst does not mention the fact that timer bugs can
result in false-positive RCU CPU stall warnings. This commit therefore
adds this to the list.
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
Signed-off-by: Boqun Feng <boqun.f...@gmail.com>
---
Documentation/RCU/stallwarn.rst | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst
index 30080ff6f406..d1ccd6039a8c 100644
--- a/Documentation/RCU/stallwarn.rst
+++ b/Documentation/RCU/stallwarn.rst
@@ -96,6 +96,13 @@ warnings:
the ``rcu_.*timer wakeup didn't happen for`` console-log message,
which will include additional debugging information.
+- A timer issue causes time to appear to jump forward, so that RCU
+ believes that the RCU CPU stall-warning timeout has been exceeded
+ when in fact much less time has passed. This could be due to
+ timer hardware bugs, timer driver bugs, or even corruption of
+ the "jiffies" global variable. These sorts of timer hardware
+ and driver bugs are not uncommon when testing new hardware.
+
- A low-level kernel issue that either fails to invoke one of the
variants of rcu_eqs_enter(true), rcu_eqs_exit(true), ct_idle_enter(),
ct_idle_exit(), ct_irq_enter(), or ct_irq_exit() on the one
--
2.39.5 (Apple Git-154)
