Patch "rcutorture: Avoid soft lockup during cpu stall" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    rcutorture: Avoid soft lockup during cpu stall

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     rcutorture-avoid-soft-lockup-during-cpu-stall.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6d708e60ee6feff3dd343905b0a7bf8b2f9602ae
Author: Wander Lairson Costa <wander@xxxxxxxxxx>
Date:   Wed Nov 10 11:37:45 2021 -0300

    rcutorture: Avoid soft lockup during cpu stall
    
    [ Upstream commit 5ff7c9f9d7e3e0f6db5b81945fa11b69d62f433a ]
    
    If we use the module stall_cpu option, we may get a soft lockup warning
    in case we also don't pass the stall_cpu_block option.
    
    Introduce the stall_no_softlockup option to avoid a soft lockup on
    cpu stall even if we don't use the stall_cpu_block option.
    
    Signed-off-by: Wander Lairson Costa <wander@xxxxxxxxxx>
    Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 968696ace8f3f..f922937eb39ad 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -46,6 +46,7 @@
 #include <linux/oom.h>
 #include <linux/tick.h>
 #include <linux/rcupdate_trace.h>
+#include <linux/nmi.h>
 
 #include "rcu.h"
 
@@ -109,6 +110,8 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 torture_param(int, stall_cpu_holdoff, 10,
 	     "Time to wait before starting stall (s).");
+torture_param(bool, stall_no_softlockup, false,
+	     "Avoid softlockup warning during cpu stall.");
 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
 torture_param(int, stall_gp_kthread, 0,
@@ -2052,6 +2055,8 @@ static int rcu_torture_stall(void *args)
 #else
 				schedule_timeout_uninterruptible(HZ);
 #endif
+			} else if (stall_no_softlockup) {
+				touch_softlockup_watchdog();
 			}
 		if (stall_cpu_irqsoff)
 			local_irq_enable();