Re: [PATCH v2 1/8] mm: migrate: remove PageTransHuge check in numamigrate_isolate_page()

[Kefeng Wang]

On 2023/8/21 20:38, Matthew Wilcox wrote:
> On Mon, Aug 21, 2023 at 07:56:17PM +0800, Kefeng Wang wrote:
> > Since we begin to convert the numa migration code to use folio, which
> > could let us to handle arbitrary sizes of folio, so drop assert that
> > we only support PageTransHuge page(PMD size) when order > 0.
>
> Have you looked at the implementation of PageTransHuge()?  Your
> description doesn't match what the code does.

oops, not only PMD size...

> > Suggested-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   mm/migrate.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index b7fa020003f3..646d8ee7f102 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -2483,8 +2483,6 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> >   	int nr_pages = thp_nr_pages(page);
> >   	int order = compound_order(page);
> >   
> > -	VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
> > -
> >   	/* Do not migrate THP mapped by multiple processes */
> >   	if (PageTransHuge(page) && total_mapcount(page) > 1)
> >   		return 0;
> > --
> > 2.41.0