linux-kernel - Re: [PATCH v2] mm/page_alloc: Consolidate unlikely handling in page_expected

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Message-ID: <923e7fa7-6476-4140-bf49-3e4e67419479@oracle.com>
Date: Fri, 21 Mar 2025 12:23:10 -0400
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: Ye Liu <ye.liu@...ux.dev>, akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Ye Liu <liuye@...inos.cn>
Subject: Re: [PATCH v2] mm/page_alloc: Consolidate unlikely handling in
 page_expected_state

On 3/21/25 2:20 AM, Ye Liu wrote:
> From: Ye Liu <liuye@...inos.cn>
> 
> This patch consolidates the handling of unlikely conditions in the
> page_expected_state function, reducing code duplication and improving
> readability.
> 
> Previously, the check_new_page_bad function contained logic to handle
> __PG_HWPOISON flags, which was called from check_new_page. This patch
> moves the handling of __PG_HWPOISON flags into the page_expected_state
> function and removes the check_new_page_bad function. The check_new_page
> function now directly calls bad_page if the page has unexpected flags.
> 
> This change simplifies the code by reducing the number of functions and
> centralizing the unlikely condition handling in one place.
> 
> Signed-off-by: Ye Liu <liuye@...inos.cn>
> 
> ---
> V2: return true instead of false in the PageHWPoison branch.
> ---
> ---
>   mm/page_alloc.c | 24 ++++++++----------------
>   1 file changed, 8 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2842da893eea..e8b95c6a96c2 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -903,6 +903,12 @@ static inline bool page_expected_state(struct page *page,
>   			(page->flags & check_flags)))
>   		return false;
>   
> +	if (unlikely(PageHWPoison(page))) {
> +		/* Don't complain about hwpoisoned pages */
> +		if (PageBuddy(page))
> +			__ClearPageBuddy(page);
> +	}
> +
>   	return true;
>   }
>   
> @@ -1586,29 +1592,15 @@ static __always_inline void page_del_and_expand(struct zone *zone,
>   	account_freepages(zone, -nr_pages, migratetype);
>   }
>   
> -static void check_new_page_bad(struct page *page)
> -{
> -	if (unlikely(PageHWPoison(page))) {
> -		/* Don't complain about hwpoisoned pages */
> -		if (PageBuddy(page))
> -			__ClearPageBuddy(page);
> -		return;
> -	}
> -
> -	bad_page(page,
> -		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
> -}
> -
>   /*
>    * This page is about to be returned from the page allocator
>    */
>   static bool check_new_page(struct page *page)
>   {
> -	if (likely(page_expected_state(page,
> -				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
> +	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_PREP)))
>   		return false;
>   
> -	check_new_page_bad(page);
> +	bad_page(page, page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
>   	return true;
>   }
>   

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>