Re: [PATCH 1/2] mm/page_ext: Add page_ext_get_phys()

[Mostafa Saleh <smostafa@google.com>]

On Mon, Jan 19, 2026 at 3:49 PM Jörg Rödel <joro@8bytes.org> wrote:
>
> On Mon, Jan 19, 2026 at 02:22:45PM +0000, Mostafa Saleh wrote:
> > +static inline struct page_ext *page_ext_get_phys(phys_addr_t phys)
>
> The name is misleading as it indicates that the function returns a physical
> address. Maybe name it page_ext_from_phys()?

I will update it.

>
> > +{
> > +     return NULL;
> > +}
> > +
> >  static inline void page_ext_put(struct page_ext *page_ext)
> >  {
> >  }
> > diff --git a/mm/page_ext.c b/mm/page_ext.c
> > index 297e4cd8ce90..5fe65a0ac4f3 100644
> > --- a/mm/page_ext.c
> > +++ b/mm/page_ext.c
> > @@ -538,6 +538,29 @@ struct page_ext *page_ext_get(const struct page *page)
> >       return page_ext;
> >  }
> >
> > +/**
> > + * page_ext_get_phys() - Get the page_ext structure for a physical address.
> > + * @phys: The physical address to query.
> > + *
> > + * This function safely gets the `struct page_ext` associated with a given
> > + * physical address. It performs validation to ensure the address corresponds
> > + * to a valid, online struct page before attempting to access it.
> > + * It should return NULL for (MMIO, ZONE_DEVICE, holes, offline memory)
>
> It should?
>

Yes, I can make it more definitive as "it returns"

Thanks,
Mostafa

> -Joerg