message: nydus-image: skip test_walk_diff for non-root
  Since we need root permission to mount.
diff: @@ -843,6 +843,7 @@ pub mod tests {
  use std::path::Path;
  use nix::sys::stat::{dev_t, makedev, mknod, Mode, SFlag};
  + use nix::unistd::geteuid;
  use vmm_sys_util::tempdir::TempDir;
  use super::*;
  @@ -913,6 +914,11 @@ pub mod tests {
  #[test]
  fn test_walk_diff() {
  + // Skip mount test for non-root.
  + if geteuid().as_raw() != 0 {
  + return;
  + }
  +
  let tmp_dir_prefix =
  std::env::var("TEST_WORKDIR_PREFIX").expect("Please specify `TEST_WORKDIR_PREFIX` env");
  