[PATCH v1 0/2] udmabuf: Add back support for mapping hugetlb pages

[Peter Xu]

On Mon, Jun 26, 2023 at 03:18:48PM -0300, Jason Gunthorpe wrote:
> On Mon, Jun 26, 2023 at 08:14:27PM +0200, David Hildenbrand wrote:
> 
> > So we might have to implement the same page migration as gup does on
> > FOLL_LONGTERM here ... maybe there are more such cases/drivers that actually
> > require that handling when simply taking pages out of the memfd, believing
> > they can hold on to them forever.
> 
> In general I would like to see an interface to FOLL_LONGTERM pin pages
> from a memfd. I would quite happily use that in iommufd as well.
> 
> It solves some problems we have there with fork/exec/etc if the pages
> are not linked to a mm_struct.

Afaiu any fd based approach should mean it'll never work with private
memories, while mm-based should be able to work on any kind.  Maybe that's
not a problem - I assume at least udmabuf should just only work with shared
memories; not sure on iommufd, though.

-- 
Peter Xu