Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754689AbXFBEBT (ORCPT ); Sat, 2 Jun 2007 00:01:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751580AbXFBEBL (ORCPT ); Sat, 2 Jun 2007 00:01:11 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:49133 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751060AbXFBEBK (ORCPT ); Sat, 2 Jun 2007 00:01:10 -0400 Date: Fri, 1 Jun 2007 21:01:09 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andrew Morton cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, jeremy@goop.org Subject: Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0) In-Reply-To: <20070601204141.f84ad72f.akpm@linux-foundation.org> Message-ID: References: <20070601204141.f84ad72f.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 870 Lines: 20 On Fri, 1 Jun 2007, Andrew Morton wrote: > > On Fri, 1 Jun 2007 18:37:46 -0700 (PDT) Christoph Lameter wrote: > > > > +#define ZERO_SIZE_PTR ((void *)16) > > Jeremy's point was a good one. The kernel _does_ use address-comparison > to determine object-inequality in an unknown but non-zero number of places. > > It is of course unlikely that this will occur in conjunction with zero-sized > objects, but who knows? The zero sized objects are always the same and have the same content of nothingness. So the kernel would find that they are the same which they indeed are. Why could this be a problem? - 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/