Hi Steven,
On Wed, 26 Apr 2023 at 23:14, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Wed, 26 Apr 2023 17:09:45 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> > Now the question is, why is this triggering on 4.19 but not in latest
> > mainline?
>
> I found it, I backported this patch and the warning goes away (at least for
> me). Can you add this and see if it makes the warning go away for you too?
I have applied this patch on stable-rc 4.19 branch and tested on
- arm64: Juno-r2
- x86_64 device
and the reported problem has been resolved.
Thanks for finding a quick fix patch.
>
> -- Steve
>
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Date: Fri, 7 Aug 2020 20:50:19 +0200
> Subject: [PATCH] sched,idle,rcu: Push rcu_idle deeper into the idle path
>
> commit 1098582a0f6c4e8fd28da0a6305f9233d02c9c1d upstream.
>
> Lots of things take locks, due to a wee bug, rcu_lockdep didn't notice
> that the locking tracepoints were using RCU.
>
> Push rcu_idle_{enter,exit}() as deep as possible into the idle paths,
> this also resolves a lot of _rcuidle()/RCU_NONIDLE() usage.
>
> Specifically, sched_clock_idle_wakeup_event() will use ktime which
> will use seqlocks which will tickle lockdep, and
> stop_critical_timings() uses lock.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Tested-by: Marco Elver <elver@xxxxxxxxxx>
> Link: https://lkml.kernel.org/r/20200821085348.310943801@xxxxxxxxxxxxx
Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
test log:
- https://lkft.validation.linaro.org/scheduler/job/6380295#L1418
- https://lkft.validation.linaro.org/scheduler/job/6380303#L1443
> ---
> drivers/cpuidle/cpuidle.c | 12 ++++++++----
> kernel/sched/idle.c | 22 ++++++++--------------
> 2 files changed, 16 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index 2d182dc1b49e..01bde6dec13a 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -140,13 +140,14 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
> * executing it contains RCU usage regarded as invalid in the idle
> * context, so tell RCU about that.
> */
> - RCU_NONIDLE(tick_freeze());
> + tick_freeze();
> /*
> * The state used here cannot be a "coupled" one, because the "coupled"
> * cpuidle mechanism enables interrupts and doing that with timekeeping
> * suspended is generally unsafe.
> */
> stop_critical_timings();
> + rcu_idle_enter();
> drv->states[index].enter_s2idle(dev, drv, index);
> if (WARN_ON_ONCE(!irqs_disabled()))
> local_irq_disable();
> @@ -155,7 +156,8 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
> * first CPU executing it calls functions containing RCU read-side
> * critical sections, so tell RCU about that.
> */
> - RCU_NONIDLE(tick_unfreeze());
> + rcu_idle_exit();
> + tick_unfreeze();
> start_critical_timings();
>
> time_end = ns_to_ktime(local_clock());
> @@ -224,16 +226,18 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
> /* Take note of the planned idle state. */
> sched_idle_set_state(target_state);
>
> - trace_cpu_idle_rcuidle(index, dev->cpu);
> + trace_cpu_idle(index, dev->cpu);
> time_start = ns_to_ktime(local_clock());
>
> stop_critical_timings();
> + rcu_idle_enter();
> entered_state = target_state->enter(dev, drv, index);
> + rcu_idle_exit();
> start_critical_timings();
>
> sched_clock_idle_wakeup_event();
> time_end = ns_to_ktime(local_clock());
> - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
> + trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
>
> /* The cpu is no longer idle or about to enter idle. */
> sched_idle_set_state(NULL);
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index 44a17366c8ec..4e3d149d64ad 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -53,17 +53,18 @@ __setup("hlt", cpu_idle_nopoll_setup);
>
> static noinline int __cpuidle cpu_idle_poll(void)
> {
> + trace_cpu_idle(0, smp_processor_id());
> + stop_critical_timings();
> rcu_idle_enter();
> - trace_cpu_idle_rcuidle(0, smp_processor_id());
> local_irq_enable();
> - stop_critical_timings();
>
> while (!tif_need_resched() &&
> - (cpu_idle_force_poll || tick_check_broadcast_expired()))
> + (cpu_idle_force_poll || tick_check_broadcast_expired()))
> cpu_relax();
> - start_critical_timings();
> - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
> +
> rcu_idle_exit();
> + start_critical_timings();
> + trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
>
> return 1;
> }
> @@ -90,7 +91,9 @@ void __cpuidle default_idle_call(void)
> local_irq_enable();
> } else {
> stop_critical_timings();
> + rcu_idle_enter();
> arch_cpu_idle();
> + rcu_idle_exit();
> start_critical_timings();
> }
> }
> @@ -148,7 +151,6 @@ static void cpuidle_idle_call(void)
>
> if (cpuidle_not_available(drv, dev)) {
> tick_nohz_idle_stop_tick();
> - rcu_idle_enter();
>
> default_idle_call();
> goto exit_idle;
> @@ -166,19 +168,15 @@ static void cpuidle_idle_call(void)
>
> if (idle_should_enter_s2idle() || dev->use_deepest_state) {
> if (idle_should_enter_s2idle()) {
> - rcu_idle_enter();
>
> entered_state = cpuidle_enter_s2idle(drv, dev);
> if (entered_state > 0) {
> local_irq_enable();
> goto exit_idle;
> }
> -
> - rcu_idle_exit();
> }
>
> tick_nohz_idle_stop_tick();
> - rcu_idle_enter();
>
> next_state = cpuidle_find_deepest_state(drv, dev);
> call_cpuidle(drv, dev, next_state);
> @@ -195,8 +193,6 @@ static void cpuidle_idle_call(void)
> else
> tick_nohz_idle_retain_tick();
>
> - rcu_idle_enter();
> -
> entered_state = call_cpuidle(drv, dev, next_state);
> /*
> * Give the governor an opportunity to reflect on the outcome
> @@ -212,8 +208,6 @@ static void cpuidle_idle_call(void)
> */
> if (WARN_ON_ONCE(irqs_disabled()))
> local_irq_enable();
> -
> - rcu_idle_exit();
> }
>
> /*
> --
> 2.39.2
- Naresh
--
Linaro LKFT
https://lkft.linaro.org
