On Mon, Aug 29, 2022, Alex Williamson wrote: > There's currently a reference count leak on the zero page. We increment > the reference via pin_user_pages_remote(), but the page is later handled > as an invalid/reserved page, therefore it's not accounted against the > user and not unpinned by our put_pfn(). Heh, kvm_pfn_to_refcounted_page() all over again. is_zone_device_page() is the other known case where a PageReserved page is refcounted. But as KVM's comment calls out, KVM's list was built through trial and error.
