linux-kernel - Re: SLUB: Return ZERO_SIZE

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Message-ID: <84144f020706041213x1d241794u98e9b3ca29865033@mail.gmail.com>
Date:	Mon, 4 Jun 2007 22:13:30 +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)

Hi Christoph,

On 6/4/07, Christoph Lameter <clameter@....com> wrote:
>         /*
> -        * We should return 0 if size == 0 (which would result in the
> -        * kmalloc caller to get NULL) but we use the smallest object
> -        * here for legacy reasons. Just issue a warning so that
> -        * we can discover locations where we do 0 sized allocations.
> +        * The behavior for zero sized allocs changes. We no longer
> +        * allocate memory but return ZERO_SIZE_PTR.
> +        * WARN so that people can review and fix their code.
>          */
>         WARN_ON_ONCE(size == 0);

I thought the whole point of this patch was to get rid of the WARN_ON
as you will get a nice oops if you dereference the pointer?
-
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