mm/migrate: preserve soft dirty in remove_migration_pte()

The code to remove a migration PTE and replace it with a device private PTE was not copying the soft dirty bit from the migration entry. This could lead to page contents not being marked dirty when faulting the page back from device private memory. Signed-off-by: Ralph Campbell <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Cc: Jerome Glisse <[email protected]> Cc: Alistair Popple <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Jason Gunthorpe <[email protected]> Cc: Bharata B Rao <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]>
marcan · Sep 5, 2020 · 3d321bf · 3d321bf
1 parent 6128763
commit 3d321bf
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/mm/migrate.c b/mm/migrate.c
@@ -249,6 +249,8 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
 		if (unlikely(is_device_private_page(new))) {
 			entry = make_device_private_entry(new, pte_write(pte));
 			pte = swp_entry_to_pte(entry);
+			if (pte_swp_soft_dirty(*pvmw.pte))
+				pte = pte_swp_mksoft_dirty(pte);
 			if (pte_swp_uffd_wp(*pvmw.pte))
 				pte = pte_swp_mkuffd_wp(pte);
 		}