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Date: Sun, 15 Feb 2009 13:36:38 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
       "Kirill A. Shutemov" <kirill@shutemov.name>,
       Christoph Lameter <cl@linux-foundation.org>,
       Matt Mackall <mpm@selenic.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, linux-crypto@vger.kernel.org,
       Geert.Uytterhoeven@sonycom.com
Subject: Re: [PATCH] Export symbol ksize()
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On Thu, 12 Feb 2009 17:55:04 +0200 Pekka Enberg <penberg@cs.helsinki.fi> wrote:

> On Thu, Feb 12, 2009 at 12:45:21PM +0200, Pekka Enberg wrote:
> > > 
> > > Because the API was being widely abused in the nommu code, for example.
> > > I'd rather not add it back for this special case which can be handled
> > > otherwise.
> 
> On Thu, 2009-02-12 at 18:50 +0800, Herbert Xu wrote:
> > I'm sorry but that's like banning the use of heaters just because
> > they can abused and cause fires.
> > 
> > I think I've said this to you before but in networking we very much
> > want to use ksize because the standard case of a 1500-byte packet
> > has loads of extra room given by kmalloc which all goes to waste
> > right now.
> > 
> > If we could use ksize then we can stuff loads of metadata in that
> > space.
> 
> OK, fair enough, I applied Kirill's patch. Thanks.
> 

Could we please have more details regarding this:

> The ksize() function is not exported to modules because it has non-standard
> behavour across different slab allocators. 

How does the behaviour differ?  It this documented?  Can we fix it?