linux-kernel - Re: [RFC/PATCH] RLIMIT_ARG

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Message-ID: <20080229190952.GM24887@devserv.devel.redhat.com>
Date:	Fri, 29 Feb 2008 14:09:52 -0500
From:	Jakub Jelinek <jakub@...hat.com>
To:	Ollie Wild <aaw@...gle.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Michael Kerrisk <michael.kerrisk@...glemail.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	michael.kerrisk@...il.com, carlos@...esourcery.com,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	linux-kernel <linux-kernel@...r.kernel.org>, drepper@...hat.com,
	mtk.manpages@...il.com
Subject: Re: [RFC/PATCH] RLIMIT_ARG_MAX

On Fri, Feb 29, 2008 at 11:01:38AM -0800, Ollie Wild wrote:
> On Fri, Feb 29, 2008 at 10:12 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > So it's not *going* to be exact even with RLIMIT_ARG_MAX, because it's
> > going to have all those other issues to contend with - on a 64-bit
> > architecture, the argument _pointers_ are often within an order of
> > magnitude of the argument strings themselves, and I don't think your patch
> > counted them as part of the argument/environemnt size (I was too lazy to
> > check the sources, but I'm pretty sure argv/env_start/end is just the
> > string space, not the pointers).
> 
> This is precisely why I picked 25% as the maximum argument size ratio.
>  In practice, that 25% can easily mean 50% or more.  If people want to
> increase this, it can probably be tweaked somewhat, but switching it
> to, say, 50% probably isn't a good idea.

I think 50% would be still fine.  And, ideally make that
MAX (RLIMIT_STACK / 2, 128KB) to avoid regressions for programs which assume
they can pass ARG_MAX args+env, even if they have say 192KB stack limit.

	Jakub
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