From: "Michael Kerrisk" <michael.kerrisk@googlemail.com>
To: "Linus Torvalds" <torvalds@linux-foundation.org>
Cc: "Peter Zijlstra" <a.p.zijlstra@chello.nl>, aaw <aaw@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
carlos@codesourcery.com, "Alan Cox" <alan@lxorguk.ukuu.org.uk>,
linux-kernel <linux-kernel@vger.kernel.org>,
drepper@redhat.com, mtk.manpages@gmail.com,
"Geoff Clare" <gwc@opengroup.org>
Subject: Re: [RFC/PATCH] RLIMIT_ARG_MAX
Date: Fri, 29 Feb 2008 20:49:16 +0100 [thread overview]
Message-ID: <c49095e30802291149t7ad01f6bl59b9083bfb41c920@mail.gmail.com> (raw)
In-Reply-To: <alpine.LFD.1.00.0802291032370.17889@woody.linux-foundation.org>
On Fri, Feb 29, 2008 at 7:39 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
>
> On Fri, 29 Feb 2008, Michael Kerrisk wrote:
> >
> > My reading of POSIX.1 (and POSIX doesn't seem very explicit on this point), is
> > that the limits on argv+environ and on stack are decoupled, since POSIX
> > specifies RLIMIT_STACK and sysconf(_SC_ARG_MAX) and doesn't specify any
> > relationship between the two.
>
> I agree. And clearly there _are_ relationships and always have been, but
> equally clearly they simply haven't been a big issue in practice, and
> nobody really cares.
Do we know that for sure?
> Usually, _SC_ARG_MAX is just so much smaller than RLIMIT_STACK that it
> makes no possible difference. Which I would actually argue we should just
> continue with: just keep _SC_ARG_MAX a smallish, irrelevant constant.
>
> We still have to have the compile-time ARG_MAX constant (as in *real*
> constant - a #define) anyway, for traditional programs, and you might as
> well make sysconf(_SC_ARG_MAX) always just match ARG_MAX.
>
> It's not like there is likely a single user of _SC_ARG_MAX that cares.
In my initial reply, I pointed out one example where users *may* care:
NPTL uses RLIMIT_STACK to determine the size of per-thread stacks. It
is conceivable that users might want to set RLIMIT_STACK < 512k, and
that would have the effect of lowering the amount of space for
argv+eviron below what the kernel has historically guaranteed. That's
an ABI change, though it's unclear whether it would impact anyone in
practice.
next prev parent reply other threads:[~2008-02-29 19:49 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-27 13:37 [RFC/PATCH] RLIMIT_ARG_MAX Peter Zijlstra
2008-02-29 16:05 ` Linus Torvalds
2008-02-29 16:58 ` Michael Kerrisk
2008-02-29 17:12 ` Linus Torvalds
2008-02-29 17:18 ` Peter Zijlstra
2008-02-29 17:29 ` Linus Torvalds
2008-02-29 17:42 ` Peter Zijlstra
2008-02-29 18:12 ` Linus Torvalds
2008-02-29 19:01 ` Ollie Wild
2008-02-29 19:09 ` Jakub Jelinek
2008-02-29 19:50 ` Linus Torvalds
2008-02-29 20:03 ` Ollie Wild
2008-03-04 20:07 ` Pavel Machek
2008-02-29 17:14 ` Peter Zijlstra
2008-02-29 17:35 ` Linus Torvalds
2008-02-29 17:55 ` Peter Zijlstra
2008-02-29 18:14 ` Linus Torvalds
2008-02-29 18:18 ` Michael Kerrisk
2008-02-29 18:39 ` Linus Torvalds
2008-02-29 19:49 ` Michael Kerrisk [this message]
2008-02-29 20:07 ` Linus Torvalds
2008-02-29 20:43 ` Michael Kerrisk
2008-02-29 21:34 ` Linus Torvalds
2008-02-29 21:57 ` Linus Torvalds
2008-03-01 14:21 ` Carlos O'Donell
2008-03-01 8:42 ` Geoff Clare
2008-02-29 18:40 ` Alan Cox
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