Commit bea1d19f authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Boqun Feng
Browse files

doc: Add broken-timing possibility to stallwarn.rst 



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: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 2014c95a

Documentation/RCU/stallwarn.rst

+7 −0
Original line number Diff line number Diff line
@@ -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