Re: [PATCH 1/5] mm: rmap: fix cache flush on THP pages

[Muchun Song]

On Mon, Jan 24, 2022 at 3:34 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Fri, Jan 21, 2022 at 03:55:11PM +0800, Muchun Song wrote:
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index b0fd9dc19eba..65670cb805d6 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -974,7 +974,7 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
> >                       if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
> >                               continue;
> >
> > -                     flush_cache_page(vma, address, page_to_pfn(page));
> > +                     flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
>
> Do we need a flush_cache_folio here given that we must be dealing with
> what effectively is a folio here?

I think it is a future improvement. I suspect it will be easy if
someone wants to backport this patch. If we do not want
someone to do this, I think it is better to introduce
flush_cache_folio in this patch. What do you think?

>
> Also please avoid the overly long line.
>

OK.

Thanks.