Always make sure buffer sizes are aligned for allocation

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.c b/fio.c
index a416856..3c01156 100644
--- a/fio.c
+++ b/fio.c
@@ -603,8 +603,8 @@
 
 	if (td->o.mem_type == MEM_SHMHUGE || td->o.mem_type == MEM_MMAPHUGE)
 		td->orig_buffer_size = (td->orig_buffer_size + td->o.hugepage_size - 1) & ~(td->o.hugepage_size - 1);
-	else
-		td->orig_buffer_size += page_mask;
+	else if (td->orig_buffer_size & page_mask)
+		td->orig_buffer_size = (td->orig_buffer_size + page_mask) & ~page_mask;
 
 	if (allocate_io_mem(td))
 		return 1;