linux-kernel - Re: [PATCH 1/6] mm: add kmalloc_array_node and kcalloc

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Message-ID: <20170927084251.kxves5ce76jz5skr@dhcp22.suse.cz>
Date:   Wed, 27 Sep 2017 10:42:51 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Johannes Thumshirn <jthumshirn@...e.de>
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Damien Le Moal <damien.lemoal@....com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 1/6] mm: add kmalloc_array_node and kcalloc_node

On Wed 27-09-17 10:20:33, Johannes Thumshirn wrote:
> We have kmalloc_array() and kcalloc() wrappers on top of kmalloc() which
> ensure us overflow free multiplication for the size of a memory
> allocation but these implementations are not NUMA-aware.
> 
> Likewise we have kmalloc_node() which is a NUMA-aware version of
> kmalloc() but the implementation is not aware of any possible overflows in
> eventual size calculations.
> 
> Introduce a combination of the two above cases to have a NUMA-node aware
> version of kmalloc_array() and kcalloc().

Yes, this is helpful. I am just wondering why we cannot have
kmalloc_array to call kmalloc_array_node with the local node as a
parameter. Maybe some sort of an optimization?

> Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>

Anyway
Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  include/linux/slab.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 41473df6dfb0..aaf4723e41b3 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -635,6 +635,22 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
>  #define kmalloc_track_caller(size, flags) \
>  	__kmalloc_track_caller(size, flags, _RET_IP_)
>  
> +static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
> +				       int node)
> +{
> +	if (size != 0 && n > SIZE_MAX / size)
> +		return NULL;
> +	if (__builtin_constant_p(n) && __builtin_constant_p(size))
> +		return kmalloc_node(n * size, flags, node);
> +	return __kmalloc_node(n * size, flags, node);
> +}
> +
> +static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
> +{
> +	return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
> +}
> +
> +
>  #ifdef CONFIG_NUMA
>  extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
>  #define kmalloc_node_track_caller(size, flags, node) \
> -- 
> 2.13.5
> 
> --
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-- 
Michal Hocko
SUSE Labs