linux-kernel - Re: SLUB: Return ZERO_SIZE

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Message-ID: <46646747.2080803@cs.helsinki.fi>
Date:	Mon, 04 Jun 2007 22:25:59 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Christoph Lameter <clameter@....com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0)

Christoph Lameter wrote:
> That is another patchset. See 
> http://marc.info/?l=linux-kernel&w=2&r=1&s=DEVELKERNEL&q=b

Oh my, I am totally confused now.

First you fix kmalloc(0) to be legal and safe. And then you want to 
DEVEL_WARN_ON_ONCE when size is zero so people can fix their code?

I don't get it.

I thought we wanted to support kmalloc(0) so that as long as you don't 
dereference the pointer, it's all legal and good. Right? So we obviously 
should shut up the WARN_ON because if you do oops, you can clearly see 
that it happened at ZERO_SIZE_PTR and have a nice stack trace anyway...

Btw, if I am again missing something totally obvious, could you please 
be so kind to send me a batch of the same pills that the smart people 
take. I am all out.

			Pekka
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