On 14.01.25 03:28, Dan Williams wrote:

Alistair Popple wrote:

quoted

The procfs mmu files such as smaps and pagemap currently ignore devdax and
fsdax pages because these pages are considered special. A future change
will start treating these as normal pages, meaning they can be exposed via
smaps and pagemap.

The only difference is that devdax and fsdax pages can never be pinned for
DMA via FOLL_LONGTERM, so add an explicit check in pte_is_pinned() to
reflect that.

I don't understand this patch.

This whole pte_is_pinned() should likely be ripped out (and I have a 
patch here to do that for a long time).

But that's a different discussion.

pin_user_pages() is also used for Direct-I/O page pinning, so the
comment about FOLL_LONGTERM is wrong, and I otherwise do not understand
what goes wrong if the only pte_is_pinned() user correctly detects the
pin state?

Yes, this patch should likely just be dropped.

Even if folio_maybe_dma_pinned() == true because of "false positives", 
it will behave just like other order-0 pages with false positives, and 
only affect soft-dirty tracking ... which nobody should be caring about 
here at all.

We would always detect the PTE as soft-dirty because we we never
	pte_wrprotect(old_pte)

Yes, nobody should care.

-- 
Cheers,

David / dhildenb