Re: [RFC PATCH v3 0/2] mm: remove extra ZONE_DEVICE struct page refcount

[Matthew Wilcox]

On Thu, Oct 01, 2020 at 11:17:13AM -0700, Ralph Campbell wrote:
> This is still an RFC because after looking at the pmem/dax code some
> more, I realized that the ZONE_DEVICE struct pages are being inserted
> into the process' page tables with vmf_insert_mixed() and a zero
> refcount on the ZONE_DEVICE struct page. This is sort of OK because
> insert_pfn() increments the reference count on the pgmap which is what
> prevents memunmap_pages() from freeing the struct pages and it doesn't
> check for a non-zero struct page reference count.
> But, any calls to get_page() will hit the VM_BUG_ON_PAGE() that
> checks for a reference count == 0.

This seems to have gone quiet.  What needs to happen to resurrect this?