linux-kernel - Re: [PATCH 1/2] Add vzalloc shortcut

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Date:	Sun, 17 Oct 2010 13:50:45 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Dave Young <hidave.darkstar@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	kvm@...r.kernel.org, Nick Piggin <npiggin@...nel.dk>
Subject: Re: [PATCH 1/2] Add vzalloc shortcut

On Sat, Oct 16, 2010 at 1:33 PM, Dave Young <hidave.darkstar@...il.com> wrote:
> Add vzalloc for convinience of vmalloc-then-memset-zero case
>
> Use __GFP_ZERO in vzalloc to zero fill the allocated memory.
Looks good to me.

There are many place we need this.
Although it affects meta pages for vmalloc as well as data pages, it's
not a big.
In this case, Maintaining code simple is better than little bit
performance overhead.

>
> Signed-off-by: Dave Young <hidave.darkstar@...il.com>
Reviewed-by: Minchan Kim <minchan.kim@...il.com>

Isn't it useful in nommu, either?


> ---
>  include/linux/vmalloc.h |    1 +
>  mm/vmalloc.c            |   13 +++++++++++++
>  2 files changed, 14 insertions(+)
>
> --- linux-2.6.orig/include/linux/vmalloc.h      2010-08-22 15:31:38.000000000 +0800
> +++ linux-2.6/include/linux/vmalloc.h   2010-10-16 10:50:54.739996121 +0800
> @@ -53,6 +53,7 @@ static inline void vmalloc_init(void)
>  #endif
>
>  extern void *vmalloc(unsigned long size);
> +extern void *vzalloc(unsigned long size);
>  extern void *vmalloc_user(unsigned long size);
>  extern void *vmalloc_node(unsigned long size, int node);
>  extern void *vmalloc_exec(unsigned long size);
> --- linux-2.6.orig/mm/vmalloc.c 2010-08-22 15:31:39.000000000 +0800
> +++ linux-2.6/mm/vmalloc.c      2010-10-16 10:51:57.126665918 +0800
> @@ -1604,6 +1604,19 @@ void *vmalloc(unsigned long size)
>  EXPORT_SYMBOL(vmalloc);
>
>  /**
> + *     vzalloc  -  allocate virtually contiguous memory with zero filled
> + *     @size:          allocation size
> + *     Allocate enough pages to cover @size from the page level
> + *     allocator and map them into contiguous kernel virtual space.
> + */
> +void *vzalloc(unsigned long size)
> +{
> +       return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
> +                               PAGE_KERNEL, -1, __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(vzalloc);
> +
> +/**
>  * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
>  * @size: allocation size
>  *
>
> --
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>
>



-- 
Kind regards,
Minchan Kim
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