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

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Message-ID: <CACZaFFOEkZqTFceV7mtC8RD890XgpCb_KZmcr_Mz7i3Jpj9SQA@mail.gmail.com>
Date: Mon, 12 Jan 2026 19:11:29 +0800
From: Vernon Yang <vernon2gm@...il.com>
To: Lance Yang <lance.yang@...ux.dev>
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 Sun, Jan 11, 2026 at 9:42 PM Lance Yang <lance.yang@...ux.dev> wrote:
>
> 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?

LGTM, I will do it in the next version.

Thank you for the review.

> 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>