rcutorture: Allow boottime stall warnings to be suppressed

In normal production, an RCU CPU stall warning at boottime is often
just as bad as at any other time.  In fact, given the desire for fast
boot, any sort of long-term stall at boot is a bad idea.  However,
heavy rcutorture testing on large hyperthreaded systems can generate
boottime RCU CPU stalls as a matter of course.  This commit therefore
provides a kernel boot parameter that suppresses reporting of boottime
RCU CPU stall warnings and similarly of rcutorture writer stalls.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index dbc22d684627..ee007b5c874f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4195,6 +4195,12 @@
 	rcupdate.rcu_cpu_stall_suppress= [KNL]
 			Suppress RCU CPU stall warning messages.
 
+	rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
+			Suppress RCU CPU stall warning messages and
+			rcutorture writer stall warnings that occur
+			during early boot, that is, during the time
+			before the init task is spawned.
+
 	rcupdate.rcu_cpu_stall_timeout= [KNL]
 			Set timeout for RCU CPU stall warning messages.