On Wed, May 19, 2021 at 09:35:10PM +1000, Alistair Popple wrote: > I think the approach you are describing is similar to what > migrate_vma_collect()/migrate_vma_unamp() does now and I think it could be > made to work. I ended up going with the GUP+unmap approach in part because > Christoph suggested it but primarily because it required less code especially > given we needed to call something to fault the page in/break COW anyway (or > extend what was there to call handle_mm_fault(), etc.). I see, thank. Would you mind add a short paragraph in the commit message talking about these two solutions and why we choose the GUP way? -- Peter Xu