Re: NOHZ tick-stop error: local softirq work is pending, handler #08!!! on Dell XPS 13 9360

Paul Menzel
2025-02-13T17:15:34Z

Dear Frederic,

Thank you very much for your help.

Am 11.02.25 um 16:02 schrieb Frederic Weisbecker:
> Le Tue, Feb 11, 2025 at 12:57:33PM +0100, Paul Menzel a écrit :

>> Am 10.02.25 um 14:26 schrieb Frederic Weisbecker:
>>> Le Mon, Feb 10, 2025 at 12:59:42PM +0100, Paul Menzel a écrit :
>>
>>>> Am 10.02.25 um 12:45 schrieb Michał Pecio:
>>>>
>>>>>>>>>>>> On Dell XPS 13 9360/0596KF, BIOS 2.21.0 06/02/2022, with Linux 6.9-rc2+
>>>>>
>>>>>> Just for the record, I am still seeing this with 6.14.0-rc1
>>>>>
>>>>> Is this a regression? If so, which versions were not affected?
>>>>
>>>> Unfortunately, I do not know. Right now, my logs go back until September
>>>> 2024.
>>>>
>>>> Sep 22 13:08:04 abreu kernel: Linux version 6.11.0-07273-g1e7530883cd2 (build@bohemianrhapsody.molgen.mpg.de) (gcc (Debian 14.2.0-5) 14.2.0, GNU ld (GNU Binutils for Debian) 2.43.1) #12 SMP PREEMPT_DYNAMIC Sun Sep 22 09:57:36 CEST 2024
>>>>
>>>>> How hard to reproduce? Wasn't it during resume from hibernation?
>>>>
>>>> It’s not easy to reproduce, and I believe it’s not related with resuming
>>>> from hibernation (which I do not use) or ACPI S3 suspend. I think, I can
>>>> force it more, when having the USB-C adapter with only the network cable
>>>> plugged into it, and then running `sudo powertop --auto-tune`. But sometimes
>>>> it seems unrelated.
>>>>
>>>>> IRQ isuses may be a red herring, this code here is a busy wait under
>>>>> spinlock. There are a few of those, they cause various problems.
>>>>>
>>>>> if (xhci_handshake(&xhci->op_regs->status,
>>>>> STS_RESTORE, 0, 100 * 1000)) {
>>>>> xhci_warn(xhci, "WARN: xHC restore state timeout\n");
>>>>> spin_unlock_irq(&xhci->lock);
>>>>> return -ETIMEDOUT;
>>>>> }
>>>>>
>>>>> This thing timing out may be close to the root cause of everything.
>>>>
>>>> Interesting. Hopefully the USB folks have an idea.
>>>
>>> Handler #08 is NET_RX. So something raised the NET_RX on some non-appropriate
>>> place, perhaps...
>>>
>>> Can I ask you one more trace dump?
>>>
>>> I need:
>>>
>>> echo 1 > /sys/kernel/tracing/events/irq/softirq_raise/enable
>>> echo 1 > /sys/kernel/tracing/options/stacktrace
>>>
>>> Unfortunately this will also involve a small patch:
>>>
>>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>>> index fa058510af9c..accd2eb8c927 100644
>>> --- a/kernel/time/tick-sched.c
>>> +++ b/kernel/time/tick-sched.c
>>> @@ -1159,6 +1159,9 @@ static bool report_idle_softirq(void)
>>> if (local_bh_blocked())
>>> return false;
>>> + trace_printk("STOP\n");
>>> + trace_dump_stack(0);
>>> + tracing_off();
>>> pr_warn("NOHZ tick-stop error: local softirq work is pending, handler #%02x!!!\n",
>>> pending);
>>> ratelimit++;
>>
>> Thank you for your help. I applied the patch on top of 6.14-rc2, and was
>> able to reproduce the issue. Please find the Linux messages attached, and
>> the trace can be downloaded [1].
>
> So here is the offender:
>
> => __raise_softirq_irqoff
> => __napi_schedule
> => rtl8152_runtime_resume.isra.0
> => rtl8152_resume
> => usb_resume_interface.isra.0
> => usb_resume_both
> => __rpm_callback
> => rpm_callback
> => rpm_resume
> => __pm_runtime_resume
> => usb_autoresume_device
> => usb_remote_wakeup
> => hub_event
> => process_one_work
> => worker_thread
> => kthread
> => ret_from_fork
> => ret_from_fork_asm
>
> It is calling napi_schedule() from a non-interrupt. And since
> ____napi_schedule() assumes to be called from an interrupt, it
> raises the softirq accordingly without waking up ksoftirqd.
>
> Can you try the following fix (untested, sorry...) ?
>
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index 468c73974046..8f6ea4e7685c 100644
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -8537,8 +8537,11 @@ static int rtl8152_runtime_resume(struct r8152 *tp)
> clear_bit(SELECTIVE_SUSPEND, &tp->flags);
> smp_mb__after_atomic();
>
> - if (!list_empty(&tp->rx_done))
> + if (!list_empty(&tp->rx_done)) {
> + local_bh_disable();
> napi_schedule(&tp->napi);
> + local_bh_enable();
> + }
>
> usb_submit_urb(tp->intr_urb, GFP_NOIO);
> } else {
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index 67964dc4db95..1bd730b881f0 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -619,6 +619,17 @@ do { \
> (!in_softirq() || in_irq() || in_nmi())); \
> } while (0)
>
> +/*
> + * Assert to be either in hardirq or in serving softirq or with
> + * softirqs disabled. Verifies a safe context to queue a softirq
> + * with __raise_softirq_irqoff().
> + */
> +#define lockdep_assert_in_interrupt() \
> +do { \
> + WARN_ON_ONCE(__lockdep_enabled && !in_interrupt()); \
> +} while (0)
> +
> +
> extern void lockdep_assert_in_softirq_func(void);
>
> #else
> @@ -634,6 +645,7 @@ extern void lockdep_assert_in_softirq_func(void);
> # define lockdep_assert_preemption_enabled() do { } while (0)
> # define lockdep_assert_preemption_disabled() do { } while (0)
> # define lockdep_assert_in_softirq() do { } while (0)
> +# define lockdep_assert_in_interrupt() do { } while (0)
> # define lockdep_assert_in_softirq_func() do { } while (0)
> #endif
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index c0021cbd28fc..80e415ccf2c8 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4666,6 +4666,7 @@ static inline void ____napi_schedule(struct softnet_data *sd,
> struct task_struct *thread;
>
> lockdep_assert_irqs_disabled();
> + lockdep_assert_in_interrupt();
>
> if (test_bit(NAPI_STATE_THREADED, &napi->state)) {
> /* Paired with smp_mb__before_atomic() in

With this diff applied, I wasn’t able to reproduce the issue. Looks
promising. Thank you very much.

Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>

Kind regards,

Paul