[PATCH] Documentation: Better document the hardlockup_panic sysctl

[PATCH] Documentation: Better document the hardlockup_panic sysctl

[Scott Wood]

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.

Signed-off-by: Scott Wood <swood@redhat.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

Re: [PATCH] Documentation: Better document the hardlockup_panic sysctl

[Christoph von Recklinghausen]

Ack

Sent from my iPhone

> On Dec 10, 2017, at 2:48 AM, Scott Wood <swood@redhat.com> 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.
> 
> Signed-off-by: Scott Wood <swood@redhat.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
> 

Re: [PATCH] Documentation: Better document the hardlockup_panic sysctl

[Don Zickus]

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@redhat.com>

> 
> Signed-off-by: Scott Wood <swood@redhat.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
> 

Re: [PATCH] Documentation: Better document the hardlockup_panic sysctl

[Jonathan Corbet]

On Sun, 10 Dec 2017 01:48:46 -0600
Scott Wood <swood@redhat.com> 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.

Applied to the docs tree, thanks.

jon