mm/apply_to_range: call pte function with lazy updates

Make the pte-level function in apply_to_range be called in lazy mmu mode,
so that any pagetable modifications can be batched.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1645,6 +1645,8 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 
 	BUG_ON(pmd_huge(*pmd));
 
+	arch_enter_lazy_mmu_mode();
+
 	token = pmd_pgtable(*pmd);
 
 	do {
@@ -1653,6 +1655,8 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 			break;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 
+	arch_leave_lazy_mmu_mode();
+
 	if (mm != &init_mm)
 		pte_unmap_unlock(pte-1, ptl);
 	return err;