From owner-freebsd-current@FreeBSD.ORG  Wed Nov 30 11:18:31 2005
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
X-Original-To: current@freebsd.org
Delivered-To: freebsd-current@FreeBSD.ORG
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id DF81816A41F
	for <current@freebsd.org>; Wed, 30 Nov 2005 11:18:31 +0000 (GMT)
	(envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 1CB0843D68
	for <current@freebsd.org>; Wed, 30 Nov 2005 11:18:29 +0000 (GMT)
	(envelope-from phk@critter.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.48.2])
	by phk.freebsd.dk (Postfix) with ESMTP id F300BBC50;
	Wed, 30 Nov 2005 11:18:27 +0000 (UTC)
To: Ulrich Spoerlein <q@galgenberg.net>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 30 Nov 2005 12:10:17 +0100."
	<20051130111017.GA67032@galgenberg.net> 
Date: Wed, 30 Nov 2005 12:18:26 +0100
Message-ID: <6861.1133349506@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: Jason Evans <jasone@canonware.com>, current@freebsd.org
Subject: Re: New libc malloc patch 
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 30 Nov 2005 11:18:32 -0000

In message <20051130111017.GA67032@galgenberg.net>, Ulrich Spoerlein writes:

>I just read that mmap() part and have to wonder: Is it possible to
>introduce something like the guard pages that OpenBSD has implemented?
>I'd love to try this out and see the dozens of applications that fail
>due to off-by-one bugs.

Guard-pages are very expensive and that is why I have not adopted
OpenBSD's patch.

I would advocate that people use one of the dedicated debugging malloc
implementations (ElectricFence ?) instead of putting too much overhead
into our default malloc.

For all practical purposes, the options J, A, X & Z are the most commonly
used.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.