linux-kernel - Re: [PATCH mm-new v5 3/5] mm: add folio_test

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Message-ID: <152ccbbe-d32f-4842-9ea8-5476076c5abc@arm.com>
Date: Fri, 23 Jan 2026 16:24:12 +0530
From: Dev Jain <dev.jain@....com>
To: Vernon Yang <vernon2gm@...il.com>, akpm@...ux-foundation.org,
 david@...nel.org
Cc: lorenzo.stoakes@...cle.com, ziy@...dia.com, baohua@...nel.org,
 lance.yang@...ux.dev, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Vernon Yang <yanglincheng@...inos.cn>
Subject: Re: [PATCH mm-new v5 3/5] mm: add folio_test_lazyfree helper


On 23/01/26 1:52 pm, Vernon Yang wrote:
> From: Vernon Yang <yanglincheng@...inos.cn>
>
> Add folio_test_lazyfree() function to identify lazy-free folios to improve
> code readability.
>
> Signed-off-by: Vernon Yang <yanglincheng@...inos.cn>
> Acked-by: David Hildenbrand (Red Hat) <david@...nel.org>
> Reviewed-by: Lance Yang <lance.yang@...ux.dev>

Thanks, this is very useful.

Reviewed-by: Dev Jain <dev.jain@....com>

> ---
>  include/linux/page-flags.h | 5 +++++
>  mm/rmap.c                  | 2 +-
>  mm/vmscan.c                | 5 ++---
>  3 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index f7a0e4af0c73..415e9f2ef616 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -724,6 +724,11 @@ static __always_inline bool folio_test_anon(const struct folio *folio)
>  	return ((unsigned long)folio->mapping & FOLIO_MAPPING_ANON) != 0;
>  }
>  
> +static __always_inline bool folio_test_lazyfree(const struct folio *folio)
> +{
> +	return folio_test_anon(folio) && !folio_test_swapbacked(folio);
> +}
> +
>  static __always_inline bool PageAnonNotKsm(const struct page *page)
>  {
>  	unsigned long flags = (unsigned long)page_folio(page)->mapping;
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 088723f909e4..6b09be06c707 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -2049,7 +2049,7 @@ 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_test_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 8643c0fb9162..1f32c74ec738 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -944,8 +944,7 @@ 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_test_lazyfree(folio)) {
>  		*dirty = false;
>  		*writeback = false;
>  		return;
> @@ -1489,7 +1488,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
>  			}
>  		}
>  
> -		if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
> +		if (folio_test_lazyfree(folio)) {
>  			/* follow __remove_mapping for reference */
>  			if (!folio_ref_freeze(folio, 1))
>  				goto keep_locked;