title: Could SIGKILL fail?
body: <p>I've encountered this piece of behavior where even after issuing <code>SIGKILL</code> using <code>kill -9</code> the process is not terminating. the command in question here is <code>cat</code></p>
  
  <pre><code># ps -ef | grep 19275
  root     19275     1  0 08:50 ?        00:00:00 [cat]
  root     22964 21578  0 09:05 pts/1    00:00:00 grep --color=auto 19275
  # kill -9 19275
  # echo $?
  0
  # ps -ef | grep 19275
  root     19275     1  0 08:50 ?        00:00:00 [cat]
  # 
  </code></pre>
  
  <p><em>some background</em>
  I've executed this command <code>for ((i=0; i&lt;28; i++)); do cat &lt;/dev/zero &gt;${i} &amp; done</code> as part of my test, for some strange reason when I tried to terminate this using </p>
  
  <p><code>pkill -TERM cat</code> did not work
  <code>pkill -9 cat</code> did not work
  <code>kill -9 pid</code> did not work</p>
  
  <p>if memory is restriction here I do believe there is enough memory available here</p>
  
  <pre><code># free -g
                total        used        free      shared  buff/cache   available
  Mem:             23          18           2           0           2           3
  Swap:            59           2          56
  </code></pre>
  
  <p>any hints  ? apart from <code>reboot</code> </p>