title: spinlock lockup suspected reasons
body: <p>What could be reasons for the following message:</p>
  
  <blockquote>
    <p><strong>BUG: spinlock lockup suspected on CPU#0, sh/11786</strong></p>
  </blockquote>
  
  <p><strong>lock: kmap_lock+0x0/0x40, .magic: dead4ead, .owner: sh/11787, .owner_cpu: 1</strong></p>