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Date: Fri, 1 Jun 2007 21:01:09 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Andrew Morton <akpm@linux-foundation.org>
cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
       jeremy@goop.org
Subject: Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0)
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On Fri, 1 Jun 2007, Andrew Morton wrote:

> > On Fri, 1 Jun 2007 18:37:46 -0700 (PDT) Christoph Lameter <clameter@sgi.com> 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?