From: Heiner Kallweit <hkallweit1@gmail.com>
To: Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Grygorii Strashko <grygorii.strashko@ti.com>
Subject: Re: Fix 80d20d35af1e ("nohz: Fix local_timer_softirq_pending()") may have revealed another problem
Date: Fri, 24 Aug 2018 19:06:32 +0200 [thread overview]
Message-ID: <d8fd3322-e982-2c9c-85e3-9b1770357520@gmail.com> (raw)
In-Reply-To: <20180824143056.GC2730@lerouge>
On 24.08.2018 16:30, Frederic Weisbecker wrote:
> On Fri, Aug 24, 2018 at 10:01:35AM +0200, Thomas Gleixner wrote:
>> On Fri, 24 Aug 2018, Heiner Kallweit wrote:
>>> On 24.08.2018 06:12, Frederic Weisbecker wrote:
>>>> On Thu, Aug 16, 2018 at 08:13:03AM +0200, Heiner Kallweit wrote:
>>>>> Recently I started to get warning "NOHZ: local_softirq_pending 202" and
>>>>> I think it's related to mentioned commit (didn't bisect it yet).
>>>>> See log from suspending.
>>>>>
>>>>> I have no reason to think the fix is wrong, it may just have revealed
>>>>> another issue which existed before and was hidden by the bug.
>>>>>
>>>>> Rgds, Heiner
>>>>>
>>>>> [ 75.073353] random: crng init done
>>>>> [ 75.073402] random: 7 urandom warning(s) missed due to ratelimiting
>>>>> [ 78.619564] PM: suspend entry (deep)
>>>>> [ 78.619675] PM: Syncing filesystems ... done.
>>>>> [ 78.653684] Freezing user space processes ... (elapsed 0.002 seconds) done.
>>>>> [ 78.656094] OOM killer disabled.
>>>>> [ 78.656113] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
>>>>> [ 78.658177] Suspending console(s) (use no_console_suspend to debug)
>>>>> [ 78.663066] nuvoton-cir 00:07: disabled
>>>>> [ 78.671817] sd 0:0:0:0: [sda] Synchronizing SCSI cache
>>>>> [ 78.672210] sd 0:0:0:0: [sda] Stopping disk
>>>>> [ 78.786651] ACPI: Preparing to enter system sleep state S3
>>>>> [ 78.789613] PM: Saving platform NVS memory
>>>>> [ 78.789759] Disabling non-boot CPUs ...
>>>>> [ 78.805154] NOHZ: local_softirq_pending 202
>>>>> [ 78.805182] NOHZ: local_softirq_pending 202
>>>>> [ 78.807102] smpboot: CPU 1 is now offline
>>>>
>>>> I've tried to reproduce with suspend on disk but got unsuccessful.
>>>>
>>>> A small question as I see someone is having a similar issue with a stable
>>>> release only. On which kernel did you trigger that: upstream or stable?
>>>>
>>>> I'll continue investigating.
>>>>
>>>> Thanks.
>>>>
>>> Affected is recent linux-next, after the commit mentioned in the subject.
>>> I can work around the warning (not sure whether it's a proper fix),
>>> see here:
>>> https://lkml.org/lkml/2018/8/18/272
>>
>> Can you try the one I posted in this thread:
>>
>> https://lkml.kernel.org/r/alpine.DEB.2.21.1808240851420.1668@nanos.tec.linutronix.de
>>
>> Also below for reference.
>>
>> Thanks,
>>
>> tglx
>>
>> 8<----------------
>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>> index 5b33e2f5c0ed..6aab9d54a331 100644
>> --- a/kernel/time/tick-sched.c
>> +++ b/kernel/time/tick-sched.c
>> @@ -888,7 +888,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
>> if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
>> static int ratelimit;
>>
>> - if (ratelimit < 10 &&
>> + if (ratelimit < 10 && !in_softirq() &&
>> (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
>> pr_warn("NOHZ: local_softirq_pending %02x\n",
>> (unsigned int) local_softirq_pending());
>
> I fear it may not work in his case because it happens in -next and we don't stop
> the idle tick from IRQ tail anymore. So we shouldn't be interrupting a softirq
> in this path. Still it's worth trying, I may well be missing something.
>
> Thanks.
>
I tested it and Frederic is right, it doesn't help. Can it be somehow related to
the cpu being brought down during suspend? Because I get the warning only during
suspend when the cpu is inactive already (but still online).
next prev parent reply other threads:[~2018-08-24 17:08 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-16 6:13 Fix 80d20d35af1e ("nohz: Fix local_timer_softirq_pending()") may have revealed another problem Heiner Kallweit
2018-08-18 11:26 ` Thomas Gleixner
2018-08-18 22:34 ` Heiner Kallweit
2018-08-24 4:12 ` Frederic Weisbecker
2018-08-24 5:59 ` Heiner Kallweit
2018-08-24 8:01 ` Thomas Gleixner
2018-08-24 14:30 ` Frederic Weisbecker
2018-08-24 17:06 ` Heiner Kallweit [this message]
2018-08-28 2:25 ` Frederic Weisbecker
2018-09-27 16:05 ` Thomas Gleixner
2018-09-28 13:18 ` Frederic Weisbecker
2018-09-28 20:35 ` Heiner Kallweit
2018-10-15 20:58 ` Heiner Kallweit
2018-12-24 21:11 ` Heiner Kallweit
2018-12-27 6:53 ` Frederic Weisbecker
2018-12-27 23:11 ` Heiner Kallweit
2018-12-28 1:31 ` Frederic Weisbecker
2018-12-28 6:34 ` Heiner Kallweit
2018-12-28 6:39 ` Heiner Kallweit
2019-01-09 22:20 ` Heiner Kallweit
2019-01-11 21:36 ` Frederic Weisbecker
2019-01-16 6:24 ` Frederic Weisbecker
2019-01-16 18:42 ` Heiner Kallweit
2019-01-24 19:37 ` Heiner Kallweit
2019-02-14 19:05 ` Heiner Kallweit
2019-02-14 21:47 ` Thomas Gleixner
2019-02-14 22:33 ` Heiner Kallweit
2019-02-15 0:31 ` Frederic Weisbecker
2019-02-16 9:14 ` Heiner Kallweit
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