On Thu, Dec 13, 2018 at 04:18:40PM -0500, Konrad Rzeszutek Wilk wrote:

.giant snip..

quoted

quoted

+	npinned = get_user_pages_fast(uaddr, npages, write, pages);
+	if (npinned != npages)
+		goto err;
+

As I said I have doubts about the whole approach, but this
implementation in particular isn't a good idea
as it keeps the page around forever.
So no THP, no NUMA rebalancing, userspace-controlled
amount of memory locked up and not accounted for.

Don't get me wrong it's a great patch in an ideal world.
But then in an ideal world no barriers smap etc are necessary at all.

So .. suggestions on how this could be accepted? As in other ways
where we still get vmap and the issues you mentioned are not troubling you?

Thanks!

I'd suggest leave vmap alone and find ways to speed up accesses
that can fault.

-- 
MST