Merge branch 'master' into for-next

Fast-forwarded to current state of Linus' tree as there are patches to be
applied for files that didn't exist on the old branch.

1 files changed, 20 insertions, 4 deletions

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 7cfa6ae02303..c3450d533611 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -33,19 +33,35 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 
 	pmd = pmd_offset(pud, addr);
 	do {
+again:
 		next = pmd_addr_end(addr, end);
-		split_huge_page_pmd(walk->mm, pmd);
-		if (pmd_none_or_clear_bad(pmd)) {
+		if (pmd_none(*pmd)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);
 			if (err)
 				break;
 			continue;
 		}
+		/*
+		 * This implies that each ->pmd_entry() handler
+		 * needs to know about pmd_trans_huge() pmds
+		 */
 		if (walk->pmd_entry)
 			err = walk->pmd_entry(pmd, addr, next, walk);
-		if (!err && walk->pte_entry)
-			err = walk_pte_range(pmd, addr, next, walk);
+		if (err)
+			break;
+
+		/*
+		 * Check this here so we only break down trans_huge
+		 * pages when we _need_ to
+		 */
+		if (!walk->pte_entry)
+			continue;
+
+		split_huge_page_pmd(walk->mm, pmd);
+		if (pmd_none_or_clear_bad(pmd))
+			goto again;
+		err = walk_pte_range(pmd, addr, next, walk);
 		if (err)
 			break;
 	} while (pmd++, addr = next, addr != end);