title: git submodule update failed with 'fatal: detected dubious ownership in repository at'
body: <p>I mounted a new hdd in my linux workstation. It looks working well. I want to download some repo in the new disk. So I execute <code>git clone XXX</code>, and it works well. But when I cd in the folder, and execute <code>git submodule update --init --recursive</code>. It failed with</p>
  <pre><code>fatal: detected dubious ownership in repository at '/media/data/users/jhu3szh/serialize'
  To add an exception for this directory, call:
  
  git config --global --add safe.directory /media/data/users/jhu3szh/serialize
  </code></pre>
  <p>I thought maybe it's just a slight warning, so I just executed <code>git config --global --add safe.directory /media/data/users/jhu3szh/serialize</code>. However, when I execute the git submodule again, more similar errors came out. There are many submodules in repo.</p>
  <p>Can someone give me some explanation what happened? I searched the error information in google, but I can hardly get useful information. Thanks in advance.</p>