On 11.02.22 17:45, Jason Gunthorpe wrote: > On Fri, Feb 11, 2022 at 05:15:25PM +0100, David Hildenbrand wrote: > >> ... I'm pretty sure we cannot FOLL_PIN DEVICE_PRIVATE pages > > Currently the only way to get a DEVICE_PRIVATE page out of the page > tables is via hmm_range_fault() and that doesn't manipulate any ref > counts. Thanks for clarifying Jason! ... and AFAIU, device exclusive entries are essentially just pointers at ordinary PageAnon() pages. So with DEVICE COHERENT we'll have the first PageAnon() ZONE_DEVICE pages mapped as present in the page tables where GUP could FOLL_PIN them. -- Thanks, David / dhildenb
