Re: [PATCH v1 4/4] mm/mmu_gather: Store and process pages in contig ranges

[David Hildenbrand]

On 25.08.23 06:09, Matthew Wilcox wrote:
> On Thu, Aug 10, 2023 at 11:33:32AM +0100, Ryan Roberts wrote:
> > +void folios_put_refs(struct folio_range *folios, int nr)
> > +{
> > +	int i;
> > +	LIST_HEAD(pages_to_free);
> > +	struct lruvec *lruvec = NULL;
> > +	unsigned long flags = 0;
> > +	unsigned int lock_batch;
> > +
> > +	for (i = 0; i < nr; i++) {
> > +		struct folio *folio = page_folio(folios[i].start);
> > +		int refs = folios[i].end - folios[i].start;
> > +
> > +		/*
> > +		 * Make sure the IRQ-safe lock-holding time does not get
> > +		 * excessive with a continuous string of pages from the
> > +		 * same lruvec. The lock is held only if lruvec != NULL.
> > +		 */
> > +		if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
> > +			unlock_page_lruvec_irqrestore(lruvec, flags);
> > +			lruvec = NULL;
> > +		}
> > +
> > +		if (is_huge_zero_page(&folio->page))
> > +			continue;
> > +
> > +		if (folio_is_zone_device(folio)) {
> > +			if (lruvec) {
> > +				unlock_page_lruvec_irqrestore(lruvec, flags);
> > +				lruvec = NULL;
> > +			}
> > +			if (put_devmap_managed_page(&folio->page))
> > +				continue;
> > +			if (folio_put_testzero(folio))
>
> We're only putting one ref for the zone_device folios?  Surely
> this should be ref_sub_and_test like below?

I suspect put_devmap_managed_page() then also needs care?

--
Cheers,

David / dhildenb