[PATCH 3.16 104/131] mm/pagewalk: remove pgd_entry() and pud_entry()

[Ben Hutchings]

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>

commit 0b1fbfe50006c41014cc25660c0e735d21c34939 upstream.

Currently no user of page table walker sets ->pgd_entry() or
->pud_entry(), so checking their existence in each loop is just wasting
CPU cycle.  So let's remove it to reduce overhead.

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16 as dependency of L1TF mitigation]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 include/linux/mm.h | 6 ------
 mm/pagewalk.c      | 9 ++-------
 2 files changed, 2 insertions(+), 13 deletions(-)

--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1114,8 +1114,6 @@ void unmap_vmas(struct mmu_gather *tlb,
 
 /**
  * mm_walk - callbacks for walk_page_range
- * @pgd_entry: if set, called for each non-empty PGD (top-level) entry
- * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
  * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
  *	       this handler is required to be able to handle
  *	       pmd_trans_huge() pmds.  They may simply choose to
@@ -1129,10 +1127,6 @@ void unmap_vmas(struct mmu_gather *tlb,
  * (see walk_page_range for more details)
  */
 struct mm_walk {
-	int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
-			 unsigned long next, struct mm_walk *walk);
-	int (*pud_entry)(pud_t *pud, unsigned long addr,
-	                 unsigned long next, struct mm_walk *walk);
 	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_entry)(pte_t *pte, unsigned long addr,
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -86,9 +86,7 @@ static int walk_pud_range(pgd_t *pgd, un
 				break;
 			continue;
 		}
-		if (walk->pud_entry)
-			err = walk->pud_entry(pud, addr, next, walk);
-		if (!err && (walk->pmd_entry || walk->pte_entry))
+		if (walk->pmd_entry || walk->pte_entry)
 			err = walk_pmd_range(pud, addr, next, walk);
 		if (err)
 			break;
@@ -237,10 +235,7 @@ int walk_page_range(unsigned long addr,
 			pgd++;
 			continue;
 		}
-		if (walk->pgd_entry)
-			err = walk->pgd_entry(pgd, addr, next, walk);
-		if (!err &&
-		    (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
+		if (walk->pmd_entry || walk->pte_entry)
 			err = walk_pud_range(pgd, addr, next, walk);
 		if (err)
 			break;