linux-kernel - Re: Fix 80d20d35af1e ("nohz: Fix local_timer_softirq_pending()") may have revealed another problem

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Date:   Fri, 24 Aug 2018 06:12:46 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Grygorii Strashko <grygorii.strashko@...com>
Subject: Re: Fix 80d20d35af1e ("nohz: Fix local_timer_softirq_pending()") may
 have revealed another problem

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.