linux-kernel - Re: [PATCH v2 3/3] mm/page_alloc: remove unnecessary next_page in break_down_buddy

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Message-ID: <20230926113417.GC1539169@ik1-406-35019.vs.sakura.ne.jp>
Date:   Tue, 26 Sep 2023 20:34:17 +0900
From:   Naoya Horiguchi <naoya.horiguchi@...ux.dev>
To:     Kemeng Shi <shikemeng@...weicloud.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, willy@...radead.org,
        naoya.horiguchi@....com, osalvador@...e.de
Subject: Re: [PATCH v2 3/3] mm/page_alloc: remove unnecessary next_page in
 break_down_buddy_pages

On Sat, Aug 26, 2023 at 11:47:45PM +0800, Kemeng Shi wrote:
> The next_page is only used to forward page in case target is in second
> harf range. Move forward page directly to remove unnecessary next_page.

s/harf/half/

> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>

> ---
>  mm/page_alloc.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index bb74b40dc195..1c35ee022dde 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6492,20 +6492,18 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page,
>  				   int migratetype)
>  {
>  	unsigned long size = 1 << high;
> -	struct page *current_buddy, *next_page;
> +	struct page *current_buddy;
>  
>  	while (high > low) {
>  		high--;
>  		size >>= 1;
>  
>  		if (target >= &page[size]) {
> -			next_page = page + size;
>  			current_buddy = page;
> +			page = page + size;
>  		} else {
> -			next_page = page;
>  			current_buddy = page + size;
>  		}
> -		page = next_page;
>  
>  		if (set_page_guard(zone, current_buddy, high, migratetype))
>  			continue;
> -- 
> 2.30.0
> 
> 
>