* [PATCH] rcutorture: Avoid soft lockup during cpu stall
@ 2021-11-09 17:46 wander
2021-11-09 20:37 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: wander @ 2021-11-09 17:46 UTC (permalink / raw)
To: Davidlohr Bueso, Paul E. McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes,
open list:TORTURE-TEST MODULES, open list:READ-COPY UPDATE (RCU)
Cc: Wander Lairson Costa
From: Wander Lairson Costa <wander@redhat.com>
If we use the module stall_cpu option, we may get a soft lockup warning
if we also don't pass the stall_cpu_block option.
We 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 40ef5417d954..0a2a9a6533d1 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -10,6 +10,7 @@
* See also: Documentation/RCU/torture.rst
*/
+#include "linux/nmi.h"
#define pr_fmt(fmt) fmt
#include <linux/types.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,
@@ -2024,6 +2027,8 @@ static int rcu_torture_stall(void *args)
stop_at))
if (stall_cpu_block)
schedule_timeout_uninterruptible(HZ);
+ else if (stall_no_softlockup)
+ touch_softlockup_watchdog();
if (stall_cpu_irqsoff)
local_irq_enable();
else if (!stall_cpu_block)
--
2.27.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rcutorture: Avoid soft lockup during cpu stall
2021-11-09 17:46 [PATCH] rcutorture: Avoid soft lockup during cpu stall wander
@ 2021-11-09 20:37 ` Paul E. McKenney
2021-11-10 12:24 ` Wander Costa
0 siblings, 1 reply; 3+ messages in thread
From: Paul E. McKenney @ 2021-11-09 20:37 UTC (permalink / raw)
To: wander
Cc: Davidlohr Bueso, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes,
open list:TORTURE-TEST MODULES, open list:READ-COPY UPDATE (RCU)
On Tue, Nov 09, 2021 at 02:46:02PM -0300, wander@redhat.com wrote:
> From: Wander Lairson Costa <wander@redhat.com>
>
> If we use the module stall_cpu option, we may get a soft lockup warning
> if we also don't pass the stall_cpu_block option.
>
> We 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>
This looks plausible to me, though it would be good to hear others'
thoughts. In the meantime, could you please forward-port this to
the "dev" branch of the -rcu tree?
https://mirrors.edge.kernel.org/pub/linux/kernel/people/paulmck/rcutodo.html
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 40ef5417d954..0a2a9a6533d1 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -10,6 +10,7 @@
> * See also: Documentation/RCU/torture.rst
> */
>
> +#include "linux/nmi.h"
> #define pr_fmt(fmt) fmt
>
> #include <linux/types.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,
> @@ -2024,6 +2027,8 @@ static int rcu_torture_stall(void *args)
> stop_at))
> if (stall_cpu_block)
> schedule_timeout_uninterruptible(HZ);
> + else if (stall_no_softlockup)
> + touch_softlockup_watchdog();
> if (stall_cpu_irqsoff)
> local_irq_enable();
> else if (!stall_cpu_block)
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] rcutorture: Avoid soft lockup during cpu stall
2021-11-09 20:37 ` Paul E. McKenney
@ 2021-11-10 12:24 ` Wander Costa
0 siblings, 0 replies; 3+ messages in thread
From: Wander Costa @ 2021-11-10 12:24 UTC (permalink / raw)
To: paulmck
Cc: wander, Davidlohr Bueso, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes,
open list:TORTURE-TEST MODULES, open list:READ-COPY UPDATE (RCU)
On Tue, Nov 9, 2021 at 5:47 PM Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Tue, Nov 09, 2021 at 02:46:02PM -0300, wander@redhat.com wrote:
> > From: Wander Lairson Costa <wander@redhat.com>
> >
> > If we use the module stall_cpu option, we may get a soft lockup warning
> > if we also don't pass the stall_cpu_block option.
> >
> > We 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>
>
> This looks plausible to me, though it would be good to hear others'
> thoughts. In the meantime, could you please forward-port this to
> the "dev" branch of the -rcu tree?
>
> https://mirrors.edge.kernel.org/pub/linux/kernel/people/paulmck/rcutodo.html
>
> Thanx, Paul
>
Thank you for the feedback. I just sent a v2 against that applies to
the aforementioned branch.
Cheers,
Wander
[snip]
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-11-09 17:46 [PATCH] rcutorture: Avoid soft lockup during cpu stall wander
2021-11-09 20:37 ` Paul E. McKenney
2021-11-10 12:24 ` Wander Costa
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