On Wed, Feb 16, 2022 at 12:23:44PM +1100, Alistair Popple wrote: > Device private and device coherent pages are not marked with pte_devmap and they > are backed by a struct page. The only way of inserting them is via migrate_vma. > The refcount is decremented in zap_pte_range() on munmap() with special handling > for device private pages. Looking at it again though I wonder if there is any > special treatment required in zap_pte_range() for device coherent pages given > they count as present pages. This is what I guessed, but we shouldn't be able to just drop pte_devmap on these pages without any other work?? Granted it does very little already.. I thought at least gup_fast needed to be touched or did this get handled by scanning the page list after the fact? Jason
