[PATCH] Documentation: Better document the softlockup_panic sysctl

[PATCH] Documentation: Better document the softlockup_panic sysctl

[Guilherme G. Piccoli]

Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the
softlockup_panic sysctl, but didn't add information about it to the file
Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
wasn't rst and had other name!).

This patch just adds the respective documentation and references it from
the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.

This patch was strongly based on Scott Wood's commit d22881dc13b6
("Documentation: Better document the hardlockup_panic sysctl").

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  6 +++---
 Documentation/admin-guide/sysctl/kernel.rst     | 13 +++++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c07815d230bc..adf77ead02c3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4515,9 +4515,9 @@
 
 			A nonzero value instructs the soft-lockup detector
 			to panic the machine when a soft-lockup occurs. This
-			is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
-			which is the respective build-time switch to that
-			functionality.
+			is also controlled by kernel.softlockup_panic sysctl
+			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
+			respective build-time switch to that functionality.
 
 	softlockup_all_cpu_backtrace=
 			[KNL] Should the soft-lockup detector generate
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index def074807cee..95b2f3256323 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -95,6 +95,7 @@ show up in /proc/sys/kernel:
 - shmmax                      [ sysv ipc ]
 - shmmni
 - softlockup_all_cpu_backtrace
+- softlockup_panic
 - soft_watchdog
 - stack_erasing
 - stop-a                      [ SPARC only ]
@@ -1029,6 +1030,18 @@ NMI.
 1: on detection capture more debug information.
 
 
+softlockup_panic:
+=================
+
+This parameter can be used to control whether the kernel panics when
+a soft lockup is detected.
+
+0: don't panic on soft lockup
+1: panic on soft lockup
+
+This can also be set using the softlockup_panic kernel parameter.
+
+
 soft_watchdog:
 ==============
 
-- 
2.24.1

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

[Kees Cook]

On Tue, Mar 10, 2020 at 12:15:03PM -0300, Guilherme G. Piccoli wrote:
> Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the
> softlockup_panic sysctl, but didn't add information about it to the file
> Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
> wasn't rst and had other name!).
> 
> This patch just adds the respective documentation and references it from
> the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
> 
> This patch was strongly based on Scott Wood's commit d22881dc13b6
> ("Documentation: Better document the hardlockup_panic sysctl").
> 
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  Documentation/admin-guide/kernel-parameters.txt |  6 +++---
>  Documentation/admin-guide/sysctl/kernel.rst     | 13 +++++++++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c07815d230bc..adf77ead02c3 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4515,9 +4515,9 @@
>  
>  			A nonzero value instructs the soft-lockup detector
>  			to panic the machine when a soft-lockup occurs. This
> -			is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
> -			which is the respective build-time switch to that
> -			functionality.
> +			is also controlled by kernel.softlockup_panic sysctl
> +			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
> +			respective build-time switch to that functionality.
>  
>  	softlockup_all_cpu_backtrace=
>  			[KNL] Should the soft-lockup detector generate
> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
> index def074807cee..95b2f3256323 100644
> --- a/Documentation/admin-guide/sysctl/kernel.rst
> +++ b/Documentation/admin-guide/sysctl/kernel.rst
> @@ -95,6 +95,7 @@ show up in /proc/sys/kernel:
>  - shmmax                      [ sysv ipc ]
>  - shmmni
>  - softlockup_all_cpu_backtrace
> +- softlockup_panic
>  - soft_watchdog
>  - stack_erasing
>  - stop-a                      [ SPARC only ]
> @@ -1029,6 +1030,18 @@ NMI.
>  1: on detection capture more debug information.
>  
>  
> +softlockup_panic:
> +=================
> +
> +This parameter can be used to control whether the kernel panics when
> +a soft lockup is detected.
> +
> +0: don't panic on soft lockup
> +1: panic on soft lockup
> +
> +This can also be set using the softlockup_panic kernel parameter.
> +
> +
>  soft_watchdog:
>  ==============
>  
> -- 
> 2.24.1
> 

-- 
Kees Cook

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

[Jonathan Corbet]

On Tue, 10 Mar 2020 12:15:03 -0300
"Guilherme G. Piccoli" <gpiccoli@canonical.com> wrote:

> Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the
> softlockup_panic sysctl, but didn't add information about it to the file
> Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
> wasn't rst and had other name!).
> 
> This patch just adds the respective documentation and references it from
> the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
> 
> This patch was strongly based on Scott Wood's commit d22881dc13b6
> ("Documentation: Better document the hardlockup_panic sysctl").
> 
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>

So this doesn't even come close to applying; could you respin it against
docs-next, please?

>  Documentation/admin-guide/kernel-parameters.txt |  6 +++---
>  Documentation/admin-guide/sysctl/kernel.rst     | 13 +++++++++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c07815d230bc..adf77ead02c3 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4515,9 +4515,9 @@
>  
>  			A nonzero value instructs the soft-lockup detector
>  			to panic the machine when a soft-lockup occurs. This
> -			is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
> -			which is the respective build-time switch to that
> -			functionality.
> +			is also controlled by kernel.softlockup_panic sysctl

..and while you're at it, make it "*the* kernel.softlockup_panic sysctl" :)

Thanks,

jon

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

[Guilherme Piccoli]

On Tue, Mar 10, 2020 at 2:05 PM Jonathan Corbet <corbet@lwn.net> wrote:
> So this doesn't even come close to applying; could you respin it against
> docs-next, please?

Sure, will resubmit soon. I understand docs-next is just linux-next
correct? I couldn't find any specific docs tree on kernel.org ...


>
> ..and while you're at it, make it "*the* kernel.softlockup_panic sysctl" :)


Sure! Thanks for the review,


Guilherme

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

[Jonathan Corbet]

On Tue, 10 Mar 2020 15:20:15 -0300
Guilherme Piccoli <gpiccoli@canonical.com> wrote:

> On Tue, Mar 10, 2020 at 2:05 PM Jonathan Corbet <corbet@lwn.net> wrote:
> > So this doesn't even come close to applying; could you respin it against
> > docs-next, please?  
> 
> Sure, will resubmit soon. I understand docs-next is just linux-next
> correct? I couldn't find any specific docs tree on kernel.org ...

That's what the MAINTAINERS file is for:

	T:	git git://git.lwn.net/linux.git docs-next

jon

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

[Guilherme Piccoli]

On Tue, Mar 10, 2020 at 3:49 PM Jonathan Corbet <corbet@lwn.net> wrote:
>
> That's what the MAINTAINERS file is for:
>
>         T:      git git://git.lwn.net/linux.git docs-next
>
> jon

Heheh thanks Jon! I got this tree and was able to apply cleanly the V2
there (on docs-next branch), so I think we're good; let me know
otherwise.
Cheers,


Guilherme

[PATCH] Documentation: Better document the softlockup_panic sysctl

[Guilherme G. Piccoli]

Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the
softlockup_panic sysctl, but didn't add information about it to the file
Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
wasn't rst and had other name!).

This patch just adds the respective documentation and references it from
the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.

This patch was strongly based on Scott Wood's commit d22881dc13b6
("Documentation: Better document the hardlockup_panic sysctl").

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  6 +++---
 Documentation/admin-guide/sysctl/kernel.rst     | 13 +++++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c07815d230bc..adf77ead02c3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4515,9 +4515,9 @@
 
 			A nonzero value instructs the soft-lockup detector
 			to panic the machine when a soft-lockup occurs. This
-			is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
-			which is the respective build-time switch to that
-			functionality.
+			is also controlled by kernel.softlockup_panic sysctl
+			and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
+			respective build-time switch to that functionality.
 
 	softlockup_all_cpu_backtrace=
 			[KNL] Should the soft-lockup detector generate
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index def074807cee..95b2f3256323 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -95,6 +95,7 @@ show up in /proc/sys/kernel:
 - shmmax                      [ sysv ipc ]
 - shmmni
 - softlockup_all_cpu_backtrace
+- softlockup_panic
 - soft_watchdog
 - stack_erasing
 - stop-a                      [ SPARC only ]
@@ -1029,6 +1030,18 @@ NMI.
 1: on detection capture more debug information.
 
 
+softlockup_panic:
+=================
+
+This parameter can be used to control whether the kernel panics when
+a soft lockup is detected.
+
+0: don't panic on soft lockup
+1: panic on soft lockup
+
+This can also be set using the softlockup_panic kernel parameter.
+
+
 soft_watchdog:
 ==============
 
-- 
2.24.1

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

[Guilherme Piccoli]

This shows as it was sent by me, 15 minutes ago...I can't even imagine
what happened, I didn't resend that.
Sorry for the inconvenience!
Cheers,


Guilherme