title: rmmod: module is in use, but modprobe -r : module not found in directory
body: <p>I cannot rmmode a scull:</p>
  
  <pre><code># /sbin/rmmod scull
  rmmod: ERROR: Module scull is in use
  
  # /sbin/modprobe scull
  modprobe: FATAL: Module scull not found in directory /lib/modules/4.19.0-9-amd64
  </code></pre>
  
  <p>Ok, so the scull is in use, but is not in modules dir? Do not get it.</p>
  
  <pre><code>#depmod #maybe it needs to inform kernel?
  </code></pre>
  
  <p>but to no avail (still get the errors above). Why?</p>
  
  <p>the question comes from my previous one <a href="https://stackoverflow.com/questions/61798226/how-to-build-external-modules-in-ubuntu?noredirect=1#comment109338772_61798226">How to build external modules in ubuntu?</a> regarding loading module (not successfuly) and the output of the kern log. Now, when I have reacted to comment from the link to add <code>printk</code> to init function (as a kind of "debuging" option), I needed to first remove the old module. But when did - the error above. From other stack-question, there were answer to use <code>modprobe -r</code>. I have tried that as well, but to no avail. So now I am confused how to remove module without to reboot or force to do (<code>rmmod -f</code>). This should be general question (<code>how to remove module, when kernel does not know about it</code>), not specific to my module, but I do not know whether it is possible to answer without knowing the specific case I am in. Nevertheless, does the <code>module in use</code> means being in the <code>/lib/modules</code> dir that <code>modprobe</code> refers?</p>