On 2023/11/6 22:20, Matthew Wilcox wrote:
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.
Sure, I will fix this, also page_try_dup_anon_rmap() for device private
entry in copy_nonpresent_pte of patch5.
