linux-kernel - Re: [PATCH] mm: be more informative in OOM task list

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Message-ID: <1113748807.15224076.1530530533122.JavaMail.zimbra@redhat.com>
Date:   Mon, 2 Jul 2018 07:22:13 -0400 (EDT)
From:   Rodrigo Freire <rfreire@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: be more informative in OOM task list

Hello Michal,

----- Original Message ----- 
> From: "Michal Hocko" <mhocko@...nel.org>
> To: "Rodrigo Freire" <rfreire@...hat.com>
> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
> Sent: Monday, July 2, 2018 6:30:43 AM
> Subject: Re: [PATCH] mm: be more informative in OOM task list
>
> On Sun 01-07-18 13:09:40, Rodrigo Freire wrote:
> > The default page memory unit of OOM task dump events might not be
> > intuitive for the non-initiated when debugging OOM events. Add
> > a small printk prior to the task dump informing that the memory
> > units are actually memory _pages_.
>
> Does this really help? I understand the the oom report might be not the
> easiest thing to grasp but wouldn't it be much better to actually add
> documentation with clarification of each part of it?

That would be great: After a quick grep -ri for oom in Documentation,
I found several other files containing its own OOM behaviour modifier
configurations. But it indeed lacks a central and canonical Doc file
which documents the OOM Killer behavior and workflows.

However, I still stand by my proposed patch: It is unobtrusive, infers
no performance issue and clarifying: I recently worked in a case (for
full disclosure: I am a far cry from a MM expert) where the sum of the
RSS pages made sense when interpreted as real kB pages. Reason: There
were processes sharing (a good amount of) memory regions, misleading
the interpretation and that misled not only me, but some other
colleagues a well: The pages was only sorted out after actually
inspecting the source code.

This patch is user-friendly and can be a great time saver to others in
the community.

I kindly request the ACKed-by ;-)

Have a great week,

- RF.