linux-kernel - Re: [PATCH v4 3/5] pid: sprinkle tasklist

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Message-ID: <CAGudoHGUvBCJaY=hnCXLo8r=GFs9wMiM4qf=0_8-rBXqexFqDg@mail.gmail.com>
Date: Wed, 5 Feb 2025 21:58:11 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>, Mateusz Guzik <mjguzik@...il.com>, ebiederm@...ssion.com, 
	oleg@...hat.com, brauner@...nel.org, akpm@...ux-foundation.org, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/5] pid: sprinkle tasklist_lock asserts

On Wed, Feb 5, 2025 at 9:42 PM Liam R. Howlett <Liam.Howlett@...cle.com> wrote:
>
> * Mateusz Guzik <mjguzik@...il.com> [250205 15:34]:
> > For this specific case I don't know what can be written in the body
> > given the really self-explanatory nature of the change, other than to
> > spell it out(?).
>
> You could say why you added it?  Is this something that was seen
> happening?
>

I guess this is a cultural discrepancy, if you will.

I spent most of my time in a codebase which is very assert-heavy and
if anything you would need to justify *not* adding some, let alone for
locking.

Plugging a gap of the sort would not require any explanation.

The kernel has numerous examples of mere comments stating that a given
lock is required or no information whatsoever, which one can only
infer from context. I'm assuming this predates lockdep. Given that
lockdep asserts are nops on production kernels there is no legitimate
reason to continue like that (or *avoid* asserting on lock state) that
I can see.

I'm going to sleep on it, type up a sentence or two, maybe reword
other commit messages and resend.

-- 
Mateusz Guzik <mjguzik gmail.com>