linux-kernel - Re: [PATCH v3 4/6] mm: add folio_is

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Message-ID: <CACZaFFNyqMD7oJv1Jqf4udFarozbQ=TPkaSMt_4Vmrq9rhoHxg@mail.gmail.com>
Date: Mon, 5 Jan 2026 10:09:52 +0800
From: Vernon Yang <vernon2gm@...il.com>
To: Lance Yang <lance.yang@...ux.dev>
Cc: baolin.wang@...ux.alibaba.com, lorenzo.stoakes@...cle.com, ziy@...dia.com, 
	dev.jain@....com, baohua@...nel.org, richard.weiyang@...il.com, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Vernon Yang <yanglincheng@...inos.cn>, akpm@...ux-foundation.org, david@...nel.org
Subject: Re: [PATCH v3 4/6] mm: add folio_is_lazyfree helper

On Sun, Jan 4, 2026 at 7:42 PM Lance Yang <lance.yang@...ux.dev> wrote:
>
> On 2026/1/4 13:41, 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                 | 4 ++--
> >   mm/vmscan.c               | 5 ++---
> >   3 files changed, 9 insertions(+), 5 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)
> > +{
> > +     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 f955f02d570e..7241a3fa8574 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -1838,7 +1838,7 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio,
> >       max_nr = (end_addr - addr) >> PAGE_SHIFT;
> >
> >       /* We only support lazyfree batching for now ... */
> > -     if (!folio_test_anon(folio) || folio_test_swapbacked(folio))
> > +     if (!folio_is_lazyfree(folio))
>
> Please rebase against mm-new. Commit[1] already supports file folios
> batching in folio_unmap_pte_batch()

Ok, thanks! I will rebase in the next version.

> +       /* We only support lazyfree or file folios batching for now ... */
> +       if (folio_test_anon(folio) && folio_test_swapbacked(folio))
>
> [1]
> https://lore.kernel.org/all/142919ac14d3cf70cba370808d85debe089df7b4.1766631066.git.baolin.wang@linux.alibaba.com/
>
> Thanks,
> Lance
>
> >               return 1;
> >       if (pte_unused(pte))
> >               return 1;
> > @@ -1934,7 +1934,7 @@ 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 670fe9fae5ba..f357f74b5a35 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -963,8 +963,7 @@ 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;
> > @@ -1501,7 +1500,7 @@ 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;
>