diff --git a/kernel/fork.c b/kernel/fork.c
index ff1cad3b7bdc5eda7d525c165c6aaa4cfe659aec..2c1802948a38034598459e8d9b8cfeb533095679 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -391,8 +391,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 		}
 		charge = 0;
 		if (mpnt->vm_flags & VM_ACCOUNT) {
-			unsigned long len;
-			len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
+			unsigned long len = vma_pages(mpnt);
+
 			if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
 				goto fail_nomem;
 			charge = len;