Re: [PATCH v5 3/8] mm: add a set_page_section_from_pfn() helper

[Li Zhe]

On Mon, Jul 6, 2026 at 11:15:36AM +0200, da...@kernel.org wrote:

> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 485df9c2dbdd..f78afa63dd3d 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2541,11 +2541,26 @@ static inline void set_page_section(struct page 
> > *page, unsigned long section)
> >     page->flags.f |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
> >  }
> >  
> > +static inline void set_page_section_from_pfn(struct page *page,
> > +                                        unsigned long pfn)
> 
> Two tab indent.

Thanks, I will fix the indentation in v6.

> > +{
> > +   set_page_section(page, pfn_to_section_nr(pfn));
> > +}
> > +
> >  static inline unsigned long memdesc_section(memdesc_flags_t mdf)
> >  {
> >     return (mdf.f >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
> >  }
> >  #else /* !SECTION_IN_PAGE_FLAGS */
> > +static inline void set_page_section(struct page *page, unsigned long 
> > section)
> > +{
> > +}
> 
> Why do we need this?

The empty set_page_section() helper is not needed. I will drop it in
v6.

> > +
> > +static inline void set_page_section_from_pfn(struct page *page,
> > +                                        unsigned long pfn)
> > +{
> > +}
> 
> Dito.

The no-op set_page_section_from_pfn() helper is still needed for
!SECTION_IN_PAGE_FLAGS so callers can use a single helper without
open-coding #ifdef SECTION_IN_PAGE_FLAGS at each callsite.

Thanks,
Zhe