linux-kernel - Re: [PATCH mm-new v4 4/6] mm: add folio_is

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Message-ID: <78a2ab5b-5ece-4d82-a229-594fb8672108@linux.dev>
Date: Sun, 11 Jan 2026 21:41:59 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: Vernon Yang <vernon2gm@...il.com>
Cc: lorenzo.stoakes@...cle.com, ziy@...dia.com, akpm@...ux-foundation.org,
 dev.jain@....com, baohua@...nel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Vernon Yang <yanglincheng@...inos.cn>,
 david@...nel.org
Subject: Re: [PATCH mm-new v4 4/6] mm: add folio_is_lazyfree helper



On 2026/1/11 20:19, Vernon Yang wrote:
> Add folio_is_lazyfree() function to identify lazy-free folios to improve
> code readability.
> 
> Signed-off-by: Vernon Yang <yanglincheng@...inos.cn>
> ---
>   include/linux/mm_inline.h | 5 +++++
>   mm/rmap.c                 | 2 +-
>   mm/vmscan.c               | 5 ++---
>   3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> index fa2d6ba811b5..65a4ae52d915 100644
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -35,6 +35,11 @@ static inline int page_is_file_lru(struct page *page)
>   	return folio_is_file_lru(page_folio(page));
>   }
>   
> +static inline int folio_is_lazyfree(const struct folio *folio)
> +{

It's 2026, could we use bool instead of int?

Yeah, I see folio_is_file_lru() uses int but that's legacy ...

> +	return folio_test_anon(folio) && !folio_test_swapbacked(folio);
> +}
> +
>   static __always_inline void __update_lru_size(struct lruvec *lruvec,
>   				enum lru_list lru, enum zone_type zid,
>   				long nr_pages)
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 336b27e00238..fd335b171ea7 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -2042,7 +2042,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
>   		}
>   
>   		if (!pvmw.pte) {
> -			if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
> +			if (folio_is_lazyfree(folio)) {
>   				if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd, folio))
>   					goto walk_done;
>   				/*
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 81828fa625ed..ad3516ff1381 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -964,8 +964,7 @@ static void folio_check_dirty_writeback(struct folio *folio,
>   	 * They could be mistakenly treated as file lru. So further anon
>   	 * test is needed.
>   	 */
> -	if (!folio_is_file_lru(folio) ||
> -	    (folio_test_anon(folio) && !folio_test_swapbacked(folio))) {
> +	if (!folio_is_file_lru(folio) || folio_is_lazyfree(folio)) {
>   		*dirty = false;
>   		*writeback = false;
>   		return;
> @@ -1506,7 +1505,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
>   			}
>   		}
>   
> -		if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
> +		if (folio_is_lazyfree(folio)) {
>   			/* follow __remove_mapping for reference */
>   			if (!folio_ref_freeze(folio, 1))
>   				goto keep_locked;

Otherwise, LGTM.

Reviewed-by: Lance Yang <lance.yang@...ux.dev>