title: Why it is not possible to use ioremap then remap_pfn_range?
body: <p>In my driver, I am trying to map an address returned from <code>ioremap</code> to a userspace address. </p>
  
  <ol>
  <li>What kind of an address is returned from <code>ioremap</code>?</li>
  <li>How is it different from a <code>kmalloc</code> address ?</li>
  <li>How can I map an address returned from <code>ioremap</code>?</li>
  <li>Which address should be inserted to <code>remap_pfn_range</code>?</li>
  </ol>