linux-kernel - Re: [PATCH RT 1/2] softirq: Avoid "local_softirq_pending" messages if ksoftirqd is blocked

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Message-ID: <20190219145826.GH21785@localhost.localdomain>
Date:   Tue, 19 Feb 2019 15:58:26 +0100
From:   Juri Lelli <juri.lelli@...il.com>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH RT 1/2] softirq: Avoid "local_softirq_pending" messages
 if ksoftirqd is blocked

Hi,

On 18/02/19 17:31, Sebastian Andrzej Siewior wrote:
> If the ksoftirqd thread has a softirq pending and is blocked on the
> `local_softirq_locks' lock then softirq_check_pending_idle() won't
> complain because the "lock owner" will mask away this softirq from the
> mask of pending softirqs.
> If ksoftirqd has an additional softirq pending then it won't be masked
> out because we never look at ksoftirqd's mask.
> 
> If there are still pending softirqs while going to idle check
> ksoftirqd's and ktimersfotd's mask before complaining about unhandled
> softirqs.
> 
> Cc: stable-rt@...r.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

I've been seeing those messages while running some stress tests (hog
tasks pinned to CPUs).

Have yet to see them after I applied this patch earlier this morning (it
usually took not much time to reproduce).

Tested-by: Juri Lelli <juri.lelli@...hat.com>

Thanks!

- Juri