On Mon, Nov 06, 2023 at 10:30:59AM +0800, Kefeng Wang wrote: > On 2023/11/5 1:20, Matthew Wilcox wrote: > > > - page_remove_rmap(page, vma, false); > > > - put_page(page); > > > + page_remove_rmap(&folio->page, vma, false); > > > + folio_put(folio); > > > > This is wrong. If we have a PTE-mapped THP, you'll remove the head page > > N times instead of removing each of N pages. > > This is device private entry, I suppose that it won't be a THP and large > folio when check migrate_vma_check_page() and migrate_vma_insert_page(), > right? I don't want to leave that kind of booby-trap in the code. Both places which currently call page_remove_rmap() should be left as referring to the page, not the folio.
