From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Kerrisk <michael.kerrisk@googlemail.com>,
aaw <aaw@google.com>, Andrew Morton <akpm@linux-foundation.org>,
michael.kerrisk@gmail.com, carlos@codesourcery.com,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel <linux-kernel@vger.kernel.org>,
drepper@redhat.com, mtk.manpages@gmail.com
Subject: Re: [RFC/PATCH] RLIMIT_ARG_MAX
Date: Fri, 29 Feb 2008 18:42:14 +0100 [thread overview]
Message-ID: <1204306934.6243.119.camel@lappy> (raw)
In-Reply-To: <alpine.LFD.1.00.0802290928200.17889@woody.linux-foundation.org>
On Fri, 2008-02-29 at 09:29 -0800, Linus Torvalds wrote:
>
> On Fri, 29 Feb 2008, Peter Zijlstra wrote:
> >
> > > ... and what's the point? We've never had it before, nobody has ever cared,
> > > and the whole notion is just stupid. Why would we want to limit it? The
> > > only thing that the kernel *cares* about is the stack size - any other
> > > size limits are always going to be arbitrary.
> >
> > Well, don't think of limiting it, but querying the limit.
> >
> > Programs like xargs would need to know how much to stuff into argv
> > before starting a new invocation.
>
> But they already can't really do that.
I think they used to use sysconf(_SC_ARG_MAX) to do that.
> More importantly, isn't it better to just use the whole stack size then
Well, we ran into trouble of freshly spawned tasks faulting on the first
stack grow. The /4 thing was to avoid that situation.
> (or just return "stack size / 4" or whatever)?
I'm all for that, trouble is that the POSIX folks specified that the
sysconf() value must be consistent during the lifetime of a process.
Which isn't true, because we can change rlimit_stack after asking. And
the linux implementation doesn't even seem to bother asking the kernel -
so there just isn't much we _can_ do here.
My suggestion was a kernel version check along with sysconf or
rlimit_stack. But I guess that made the userspace people puke :-)
next prev parent reply other threads:[~2008-02-29 17:43 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 [this message]
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
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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