11 Feb
2022
11 Feb
'22
4:49 p.m.
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.
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Thanks,
David / dhildenb