diff --git a/mm/mmap.c b/mm/mmap.c
index f681e184..8468ffd 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -955,7 +955,7 @@
 	if (is_mergeable_vma(vma, file, vm_flags) &&
 	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 		pgoff_t vm_pglen;
-		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+		vm_pglen = vma_pages(vma);
 		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
 			return 1;
 	}