[PATCH v11 00/25] mm/gup: track dma-pinned pages: FOLL_PIN

[Jason Gunthorpe]

On Fri, Dec 20, 2019 at 04:32:13PM -0800, Dan Williams wrote:

> > > There's already a limit, it's just a much larger one. :) What does "no limit"
> > > really mean, numerically, to you in this case?
> >
> > I guess I mean 'hidden limit' - hitting the limit and failing would
> > be managable.
> >
> > I think 7 is probably too low though, but we are not using 1GB huge
> > pages, only 2M..
> 
> What about RDMA to 1GB-hugetlbfs and 1GB-device-dax mappings?

I don't think the failing testing is doing that.

It is also less likely that 1GB regions will need multi-mapping, IMHO.

Jason