Re: [PATCH v7 11/16] mm/highmem: introduce clear_user_highpages()

[David Hildenbrand]

On 25.09.25 07:26, Ankur Arora wrote:
> David Hildenbrand <david@xxxxxxxxxx> writes:
>
> > On 23.09.25 22:34, Ankur Arora wrote:
> > > David Hildenbrand <david@xxxxxxxxxx> writes:
> > >
> > > > On 17.09.25 17:24, Ankur Arora wrote:
> > > > > Define clear_user_highpages() which clears pages sequentially using
> > > > > the single page variant.
> > > > > With !CONFIG_HIGHMEM, pages are contiguous so use the range clearing
> > > > > primitive clear_user_pages().
> > > > > Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
> > > > > ---
> > > > >     include/linux/highmem.h | 18 ++++++++++++++++++
> > > > >     1 file changed, 18 insertions(+)
> > > > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> > > > > index 6234f316468c..ed609987e24d 100644
> > > > > --- a/include/linux/highmem.h
> > > > > +++ b/include/linux/highmem.h
> > > > > @@ -207,6 +207,24 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
> > > > >     }
> > > > >     #endif
> > > > >     +#ifndef clear_user_highpages
> > > >
> > > > Maybe we can add a simple kernel doc that points at the doc of clear_user_pages,
> > > > but makes it clear that this for pages that might reside in highmem.
> > > Didn't add one because clear_user_highpage() didn't have one. Will add
> > > for both.
> >
> > Doesn't have to be excessive. But even I have to keep reminding myself when to
> > use clear_page(), clear_user_page(), clear_user_highpage() ...
>
> And now all the multi-page variants. Really motivates the removal of
> the HIGHMEM stuff.

:) I'm afraid it will stick around for a couple of years to come.

--
Cheers

David / dhildenb