[PATCH v3 0/1] rcutorture: Avoid soft lockup during cpu stall

[PATCH v3 0/1] rcutorture: Avoid soft lockup during cpu stall

[Wander Lairson Costa]

This version fixes the include in the beggining of the source file.

The patch applies cleanly to 

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git

Wander Lairson Costa (1):
  rcutorture: Avoid soft lockup during cpu stall

 kernel/rcu/rcutorture.c | 5 +++++
 1 file changed, 5 insertions(+)

-- 
2.27.0

[PATCH v3 1/1] rcutorture: Avoid soft lockup during cpu stall

[Wander Lairson Costa]

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@redhat.com>
---
 kernel/rcu/rcutorture.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 36a273589a35..bc854f935548 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"
 
@@ -112,6 +113,8 @@ 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,
@@ -2085,6 +2088,8 @@ 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();
-- 
2.27.0

Re: [PATCH v3 1/1] rcutorture: Avoid soft lockup during cpu stall

[Paul E. McKenney]

On Wed, Nov 10, 2021 at 11:37:45AM -0300, Wander Lairson Costa wrote:
> 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@redhat.com>

Queued for review and further testing, thank you!

							Thanx, Paul

> ---
>  kernel/rcu/rcutorture.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 36a273589a35..bc854f935548 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"
>  
> @@ -112,6 +113,8 @@ 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,
> @@ -2085,6 +2088,8 @@ 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();
> -- 
> 2.27.0
>