linux-kernel - Re: [PATCH] Documentation: Better document the hardlockup

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Date:   Mon, 11 Dec 2017 09:43:48 -0500
From:   Don Zickus <dzickus@...hat.com>
To:     Scott Wood <swood@...hat.com>
Cc:     Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        Christoph von Recklinghausen <crecklin@...hat.com>
Subject: Re: [PATCH] Documentation: Better document the hardlockup_panic
 sysctl

On Sun, Dec 10, 2017 at 01:48:46AM -0600, Scott Wood wrote:
> Commit ac1f591249d95372f ("kernel/watchdog.c: add sysctl knob
> hardlockup_panic") added the hardlockup_panic sysctl, but did not add it
> to Documentation/sysctl/kernel.txt.  Add this, and reference it from the
> corresponding entry in Documentation/admin-guide/kernel-parameters.txt.

Acked-by: Don Zickus <dzickus@...hat.com>

> 
> Signed-off-by: Scott Wood <swood@...hat.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  3 +++
>  Documentation/sysctl/kernel.txt                 | 14 ++++++++++++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 6571fbfdb2a1..dfb7c35b5826 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2538,6 +2538,9 @@
>  			This is useful when you use a panic=... timeout and
>  			need the box quickly up again.
>  
> +			These settings can be accessed at runtime via
> +			the nmi_watchdog and hardlockup_panic sysctls.
> +
>  	netpoll.carrier_timeout=
>  			[NET] Specifies amount of time (in seconds) that
>  			netpoll should wait for a carrier. By default netpoll
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index 694968c7523c..63663039acb7 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -34,6 +34,7 @@ show up in /proc/sys/kernel:
>  - hostname
>  - hotplug
>  - hardlockup_all_cpu_backtrace
> +- hardlockup_panic
>  - hung_task_panic
>  - hung_task_check_count
>  - hung_task_timeout_secs
> @@ -313,6 +314,19 @@ will be initiated.
>  1: on detection capture more debug information.
>  ==============================================================
>  
> +hardlockup_panic:
> +
> +This parameter can be used to control whether the kernel panics
> +when a hard lockup is detected.
> +
> +   0 - don't panic on hard lockup
> +   1 - panic on hard lockup
> +
> +See Documentation/lockup-watchdogs.txt for more information.  This can
> +also be set using the nmi_watchdog kernel parameter.
> +
> +==============================================================
> +
>  hotplug:
>  
>  Path for the hotplug policy agent.
> -- 
> 2.9.5
>