[PATCH 05/45] mm/pagewalk: Enable walk_pmd_range to handle cont-pmds

[Oscar Salvador <osalvador@suse.de>]

HugeTLB pages can be cont-pmd mapped, so teach walk_pmd_range to
handle those.
This will save us some cycles as we do it in one-shot instead of
calling in multiple times.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/pgtable.h | 12 ++++++++++++
 mm/pagewalk.c           | 12 +++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 2a6a3cccfc36..3a7b8751747e 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1914,6 +1914,18 @@ typedef unsigned int pgtbl_mod_mask;
 #define __pte_leaf_size(x,y) pte_leaf_size(y)
 #endif
 
+#ifndef pmd_cont
+#define pmd_cont(x) false
+#endif
+
+#ifndef CONT_PMD_SIZE
+#define CONT_PMD_SIZE 0
+#endif
+
+#ifndef CONT_PMDS
+#define CONT_PMDS 0
+#endif
+
 /*
  * We always define pmd_pfn for all archs as it's used in lots of generic
  * code.  Now it happens too for pud_pfn (and can happen for larger
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d93e77411482..a9c36f9e9820 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -81,11 +81,18 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 	int depth = real_depth(3);
+	int cont_pmds;
 
 	pmd = pmd_offset(pud, addr);
 	do {
 again:
-		next = pmd_addr_end(addr, end);
+		if (pmd_cont(*pmd)) {
+			cont_pmds = CONT_PMDS;
+			next = pmd_cont_addr_end(addr, end);
+		} else {
+			cont_pmds = 1;
+			next = pmd_addr_end(addr, end);
+		}
 		if (pmd_none(*pmd)) {
 			if (ops->pte_hole)
 				err = ops->pte_hole(addr, next, depth, walk);
@@ -126,8 +133,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 
 		if (walk->action == ACTION_AGAIN)
 			goto again;
-
-	} while (pmd++, addr = next, addr != end);
+	} while (pmd += cont_pmds, addr = next, addr != end);
 
 	return err;
 }
-- 
2.26.2