1 files changed, 11 insertions, 12 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index aee61a980374..e3065c9edb55 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -296,19 +296,16 @@ bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
 }
 
 static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
-					  struct folio *folio,
-					  unsigned long idx)
+		struct folio *folio, pte_t old_pte, unsigned long idx)
 {
 	struct page *page = folio_page(folio, idx);
-	bool contains_data;
 	pte_t newpte;
-	void *addr;
 
 	if (PageCompound(page))
 		return false;
 	VM_BUG_ON_PAGE(!PageAnon(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page);
+	VM_BUG_ON_PAGE(pte_present(old_pte), page);
 
 	if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) ||
 	    mm_forbids_zeropage(pvmw->vma->vm_mm))
@@ -319,15 +316,17 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
 	 * this subpage has been non present. If the subpage is only zero-filled
 	 * then map it to the shared zeropage.
 	 */
-	addr = kmap_local_page(page);
-	contains_data = memchr_inv(addr, 0, PAGE_SIZE);
-	kunmap_local(addr);
-
-	if (contains_data)
+	if (!pages_identical(page, ZERO_PAGE(0)))
 		return false;
 
 	newpte = pte_mkspecial(pfn_pte(my_zero_pfn(pvmw->address),
 					pvmw->vma->vm_page_prot));
+
+	if (pte_swp_soft_dirty(old_pte))
+		newpte = pte_mksoft_dirty(newpte);
+	if (pte_swp_uffd_wp(old_pte))
+		newpte = pte_mkuffd_wp(newpte);
+
 	set_pte_at(pvmw->vma->vm_mm, pvmw->address, pvmw->pte, newpte);
 
 	dec_mm_counter(pvmw->vma->vm_mm, mm_counter(folio));
@@ -370,13 +369,13 @@ static bool remove_migration_pte(struct folio *folio,
 			continue;
 		}
 #endif
+		old_pte = ptep_get(pvmw.pte);
 		if (rmap_walk_arg->map_unused_to_zeropage &&
-		    try_to_map_unused_to_zeropage(&pvmw, folio, idx))
+		    try_to_map_unused_to_zeropage(&pvmw, folio, old_pte, idx))
 			continue;
 
 		folio_get(folio);
 		pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
-		old_pte = ptep_get(pvmw.pte);
 
 		entry = pte_to_swp_entry(old_pte);
 		if (!is_migration_entry_young(entry))