[PATCH v4 4/6] mm: pvmw: add support for walking devmap pages

[Muchun Song]

The devmap pages can not use page_vma_mapped_walk() to check if a huge
devmap page is mapped into a vma.  Add support for walking huge devmap
pages so that DAX can use it in the next patch.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 mm/page_vma_mapped.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 1187f9c1ec5b..f9ffa84adf4d 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -210,10 +210,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 		 */
 		pmde = READ_ONCE(*pvmw->pmd);
 
-		if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
+		if (pmd_trans_huge(pmde) || pmd_devmap(pmde) ||
+		    is_pmd_migration_entry(pmde)) {
 			pvmw->ptl = pmd_lock(mm, pvmw->pmd);
 			pmde = *pvmw->pmd;
-			if (likely(pmd_trans_huge(pmde))) {
+			if (likely(pmd_trans_huge(pmde) || pmd_devmap(pmde))) {
 				if (pvmw->flags & PVMW_MIGRATION)
 					return not_found(pvmw);
 				if (!check_pmd(pmd_pfn(pmde), pvmw))
-- 
2.11.0