Re: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()

[Naoya Horiguchi]

On Tue, Nov 10, 2015 at 05:41:08AM +0800, Chen Gang wrote:
> From 7050c267d8dda220226067039d815593d2f9a874 Mon Sep 17 00:00:00 2001
> From: Chen Gang <gang.chen.5i5j@xxxxxxxxx>
> Date: Tue, 10 Nov 2015 05:32:38 +0800
> Subject: [PATCH] mm/mmap.c: Remove redundant local variables for may_expand_vm()
> 
> After merge the related code into one line, the code is still simple and
> meaningful enough.
> 
> Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx>

I agree that this function can be cleaned up.

> ---
>  mm/mmap.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 2ce04a6..a515260 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2988,12 +2988,7 @@ out:
>   */
>  int may_expand_vm(struct mm_struct *mm, unsigned long npages)

marking inline? 

>  {
> -	unsigned long cur = mm->total_vm;	/* pages */
> -	unsigned long lim;
> -
> -	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
> -
> -	if (cur + npages > lim)
> +	if (mm->total_vm + npages > (rlimit(RLIMIT_AS) >> PAGE_SHIFT))
>  		return 0;
>  	return 1;

How about doing simply

	return mm->total_vm + npages <= (rlimit(RLIMIT_AS) >> PAGE_SHIFT);

? These changes save some bytes :)

   text    data     bss     dec     hex filename 
  20566    2250      40   22856    5948 mm/mmap.o (before)

   text    data     bss     dec     hex filename 
  20542    2250      40   22832    5930 mm/mmap.o (after)

Thanks,
Naoya Horiguchi--
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