Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756523AbXFDOm7 (ORCPT ); Mon, 4 Jun 2007 10:42:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755275AbXFDOmw (ORCPT ); Mon, 4 Jun 2007 10:42:52 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:39723 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754845AbXFDOmv (ORCPT ); Mon, 4 Jun 2007 10:42:51 -0400 Date: Mon, 4 Jun 2007 15:44:24 +0100 From: Alan Cox To: Matt Mackall Cc: Christoph Lameter , Andrew Morton , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, jeremy@goop.org Subject: Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0) Message-ID: <20070604154424.5c4750f7@the-village.bc.nu> In-Reply-To: <20070603161528.GO11166@waste.org> References: <20070601204141.f84ad72f.akpm@linux-foundation.org> <20070601213117.1178e8e0.akpm@linux-foundation.org> <20070603161528.GO11166@waste.org> X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.8; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 758 Lines: 19 > > > I agree the risk is low, but if something _does_ blow up, it will do so subtly. > > Arguable the proposed badptr behavior is correct. It's basically "how many > angels can dance on the head of a pin"? All the returned pointers are > at least 0 bytes away from the previous one. C++ very carefully keeps objects of zero size at differing addresses to avoid exactly this kind of pointer confusion. Given the trivial fix is simply size += !size; at the start of malloc what is there worth arguing about ? - 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/