title: when linux kernel is crashed how kernel stack and call trace logged to console?
body: <pre><code>Pid: 16251, comm: bash Not tainted 2.6.32.59 #78
  
  Call Trace:
  
   [&lt;ffffffff81367a50&gt;] ? do_page_fault+0x1b6/0x394
  
   [&lt;ffffffff8136583f&gt;] ? page_fault+0x1f/0x30
  
   [&lt;ffffffff812160c5&gt;] ? sysrq_handle_crash+0xd/0x16
  
   [&lt;ffffffff812164be&gt;] ? __handle_sysrq+0xaf/0x14a
  
   [&lt;ffffffff8121659e&gt;] ? write_sysrq_trigger+0x45/0x4c
  
   [&lt;ffffffff81216559&gt;] ? write_sysrq_trigger+0x0/0x4c
  
   [&lt;ffffffff81116468&gt;] ? proc_reg_write+0x85/0xa6
  
   [&lt;ffffffff810d54cc&gt;] ? vfs_write+0xa8/0x14c
  
   [&lt;ffffffff810d566e&gt;] ? sys_write+0x48/0x9e
  
   [&lt;ffffffff8102d025&gt;] ? sysenter_dispatch+0x7/0x2b
  
  BUG: unable to handle kernel NULL pointer dereference at (null)
  
  IP: [&lt;ffffffff812160c5&gt;] sysrq_handle_crash+0xd/0x16
  
  PGD 26ad8f067 PUD 1e2aa6067 PMD 0 
  
  Oops: 0002 [#1] SMP 
  </code></pre>
  
  <p>which component of linux logs these Info to console?</p>