From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-mm@kvack.org
Subject: Re: slab allocators: MAX_ORDER one off fix
Date: Sat, 23 Jun 2007 09:53:34 -0700 [thread overview]
Message-ID: <20070623095334.51f80e94.akpm@linux-foundation.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0706221100270.17293@schroedinger.engr.sgi.com>
> On Fri, 22 Jun 2007 11:02:17 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> MAX_ORDER is the first order that is not possible.
>
> Use MAX_ORDER - 1 to calculate the larges possible object size in slab.h
>
> Signed-off-by: Christoph Lameter <clameter@sgi.com>
>
> ---
> include/linux/slab.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.22-rc4-mm2/include/linux/slab.h
> ===================================================================
> --- linux-2.6.22-rc4-mm2.orig/include/linux/slab.h 2007-06-22 10:46:12.000000000 -0700
> +++ linux-2.6.22-rc4-mm2/include/linux/slab.h 2007-06-22 10:46:53.000000000 -0700
> @@ -133,8 +133,8 @@ static inline void *kmem_cache_alloc_nod
> * to do various tricks to work around compiler limitations in order to
> * ensure proper constant folding.
> */
> -#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT) <= 25 ? \
> - (MAX_ORDER + PAGE_SHIFT) : 25)
> +#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
> + (MAX_ORDER + PAGE_SHIFT - 1) : 25)
>
> #define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_HIGH)
> #define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
I'm too lazy to look. What are the consequences of deferring this to
2.6.23? Oversized kmallocs will still get a runtime failure, so no real
problem?
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next prev parent reply other threads:[~2007-06-23 16:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-22 18:02 Christoph Lameter
2007-06-23 16:53 ` Andrew Morton [this message]
2007-06-25 13:06 ` Christoph Lameter
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