linux-kernel - Re: [PATCH] PM / Suspend: Avoid soft lockup warning with suspend

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Date:   Thu, 23 Sep 2021 12:29:10 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        "open list:HIBERNATION (aka Software Suspend, aka swsusp)" 
        <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] PM / Suspend: Avoid soft lockup warning with suspend_test

On 9/23/21 11:51 AM, Florian Fainelli wrote:
> When testing with a large (>= 22 seconds) pm_test_delay we can see the
> NMI soft lockup barfing at us because a task has been blocked for too
> long. This can be reproduced with:
> 
> 	echo devices > /sys/power/pm_test
> 	echo 30 > /sys/module/suspend/parameters/pm_test_delay
> 
> Unroll the loop and touch the NMI watchdog every 1s to avoid the lockup
> warnings.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

Looks like I cannot reproduce the NMI soft lockup warnings with 5.10 and
newer, however I can easily trigger RCU stalls. Let me sleep on it for a
bit and see what needs fixing in 5.15 and newer. Any feedback welcome.
-- 
Florian