Re: [PATCH -next v2 1/7] mm: page_idle: Convert page idle to use folios

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

On 2022/12/28 2:14, Matthew Wilcox wrote:
> On Tue, Dec 27, 2022 at 08:27:08PM +0800, Kefeng Wang wrote:
> > -static struct page *page_idle_get_page(unsigned long pfn)
> > +static struct folio *page_idle_get_folio(unsigned long pfn)
> >   {
> >   	struct page *page = pfn_to_online_page(pfn);
> > +	struct folio *folio;
> >   
> > -	if (!page || !PageLRU(page) ||
> > -	    !get_page_unless_zero(page))
> > +	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
> >   		return NULL;
>
> Mmmm, no.  PageLRU hides a compound_head() call.  Try doing this instead:
>
> 	if (!page || PageTail(page))
> 		return NULL;
> 	folio = page_folio(page);
> 	if (!folio_test_lru(folio) || !folio_try_get(folio))
> 		return NULL;
> 	if (page_folio(page) != folio || !folio_test_lru(folio)) {
> 		folio_put(folio);
> 		folio = NULL;
> 	}
Thanks Matthew, this is more complete, will update.
> 	return NULL;