Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761354AbYB2Rnc (ORCPT ); Fri, 29 Feb 2008 12:43:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760815AbYB2Rm5 (ORCPT ); Fri, 29 Feb 2008 12:42:57 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:53856 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760715AbYB2Rm4 (ORCPT ); Fri, 29 Feb 2008 12:42:56 -0500 Subject: Re: [RFC/PATCH] RLIMIT_ARG_MAX From: Peter Zijlstra To: Linus Torvalds Cc: Michael Kerrisk , aaw , Andrew Morton , michael.kerrisk@gmail.com, carlos@codesourcery.com, Alan Cox , linux-kernel , drepper@redhat.com, mtk.manpages@gmail.com In-Reply-To: References: <1204119455.6242.403.camel@lappy> <1204305488.6243.113.camel@lappy> Content-Type: text/plain Date: Fri, 29 Feb 2008 18:42:14 +0100 Message-Id: <1204306934.6243.119.camel@lappy> Mime-Version: 1.0 X-Mailer: Evolution 2.21.90 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1643 Lines: 40 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 :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/