Re: Fwd: [PATCH] mm: add config option to select the initial overcommit mode

Andy Whitcroft
2016-05-10T12:39:46Z

On Tue, May 10, 2016 at 02:00:47PM +0200, Sebastian Frias wrote:
> Hi,
>
> Using checkpatch.pl on the forwarded patch results in:
>
> WARNING: please write a paragraph that describes the config symbol fully
> #57: FILE: mm/Kconfig:451:
> + config OVERCOMMIT_GUESS
>
> WARNING: please write a paragraph that describes the config symbol fully
> #64: FILE: mm/Kconfig:458:
> + config OVERCOMMIT_ALWAYS
>
> but there is a 'help' section for those 'config' sections.
> NOTE: I followed the same indentation than the code laying just above the place where I inserted mine.
>
> I think it is a false positive, what do you think?
>
> Best regards,
>
> Sebastian

Well, I am expecting the issue to be that the per option help is not
indented within the option like I am expecting ...

> Date: Tue, 10 May 2016 13:56:30 +0200
> From: Sebastian Frias <sf84@laposte.net>
> To: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>, Michal
> Hocko <mhocko@suse.com>, Linus Torvalds <torvalds@linux-foundation.org>
> CC: LKML <linux-kernel@vger.kernel.org>, mason <slash.tmp@free.fr>
> Subject: [PATCH] mm: add config option to select the initial overcommit mode
> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101
> Thunderbird/31.2.0
>
> Currently the initial value of the overcommit mode is OVERCOMMIT_GUESS.
> However, on embedded systems it is usually better to disable overcommit
> to avoid waking up the OOM-killer and its well known undesirable
> side-effects.
>
> This config option allows to setup the initial overcommit mode to any of
> the 3 available values, OVERCOMMIT_GUESS (which remains as default),
> OVERCOMMIT_ALWAYS and OVERCOMMIT_NEVER.
> The overcommit mode can still be changed thru sysctl after the system
> boots up.
>
> This config option depends on CONFIG_EXPERT.
> This patch does not introduces functional changes.
>
> Signed-off-by: Sebastian Frias <sf84@laposte.net>
> ---
>
> NOTE: I understand that the overcommit mode can be changed dynamically thru
> sysctl, but on embedded systems, where we know in advance that overcommit
> will be disabled, there's no reason to postpone such setting.
>
> I would also be interested in knowing if you guys think this option should
> disable sysctl access for overcommit mode, essentially hardcoding the
> overcommit mode when this option is used.
>
> NOTE2: I tried to track down the history of overcommit but back then there
> were no single patches apparently and the patch that appears to have
> introduced the first overcommit mode (OVERCOMMIT_ALWAYS) is commit
> 9334eab8a36f ("Import 2.1.27"). OVERCOMMIT_NEVER was introduced with commit
> 502bff0685b2 ("[PATCH] strict overcommit").
> My understanding is that prior to commit 9334eab8a36f ("Import 2.1.27")
> there was no overcommit, is that correct?
>
> NOTE3: checkpatch.pl is warning about missing description for the config
> symbols ("please write a paragraph that describes the config symbol fully")
> but my understanding is that that is a false positive (or the warning message
> not clear enough for me to understand it) considering that I have added
> 'help' sections for each 'config' section.
> ---
> mm/Kconfig | 32 ++++++++++++++++++++++++++++++++
> mm/util.c | 8 +++++++-
> 2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index abb7dcf..6dad57d 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -439,6 +439,38 @@ choice
> benefit.
> endchoice
>
> +choice
> + prompt "Overcommit Mode"
> + default OVERCOMMIT_GUESS
> + depends on EXPERT
> + help
> + Selects the initial value for Overcommit mode.
> +
> + NOTE: The overcommit mode can be changed dynamically through sysctl.
> +
> + config OVERCOMMIT_GUESS
> + bool "Guess"

I am expecting the help below to be indented at the same level as the
bool above. As you have done with the help for the choice itself. I am
pretty sure checkpatch is assuming the "contents" of the config item are
all intented more than it is.

> + help
> + Selecting this option forces the initial value of overcommit mode to
> + "Guess" overcommits. This is the default value.
> + See Documentation/vm/overcommit-accounting for more information.
[...]

-apw