linux-kernel - Re: [PATCH 2/3] kernel/pid: Remove default pid

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Message-ID: <dfoqa6pd2vyk6zcnc7zulojiho5uezgeyv2a7h6i7dm2oaawgt@7h33yk4pgiw4>
Date: Mon, 13 May 2024 19:26:47 +0200
From: Michal Koutný <mkoutny@...e.com>
To: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Cc: Steven Rostedt <rostedt@...dmis.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
	Christian Brauner <brauner@...nel.org>, Oleg Nesterov <oleg@...hat.com>, 
	Kent Overstreet <kent.overstreet@...ux.dev>, Kees Cook <keescook@...omium.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Tycho Andersen <tandersen@...flix.com>, 
	Jens Axboe <axboe@...nel.dk>, Aleksa Sarai <cyphar@...har.com>
Subject: Re: [PATCH 2/3] kernel/pid: Remove default pid_max value

On Mon, Apr 08, 2024 at 04:58:18PM GMT, Michal Koutný <mkoutny@...e.com> wrote:
> The kernel provides mechanisms, while it should not imply policies --
> default pid_max seems to be an example of the policy that does not fit
> all. At the same time pid_max must have some value assigned, so use the
> end of the allowed range -- pid_max_max.
> 
> This change thus increases initial pid_max from 32k to 4M (x86_64
> defconfig).

Out of curiosity I dug out the commit
	acdc721fe26d ("[PATCH] pid-max-2.5.33-A0") v2.5.34~5
that introduced the 32k default. The commit message doesn't say why such
a sudden change though.
Previously, the limit was 1G of pids (i.e. effectively no default limit
like the intention of this series).

Honestly, I expected more enthusiasm or reasons against removing the
default value of pid_max. Is this really not of interest to anyone?

(Thanks, Andrew, for your responses. I don't plan to pursue this further
should there be no more interest in having less default limit values in
kernel.)

Regards,
Michal

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