This modifies x86's dump_stack() to print out just the backtrace, not
the stack contents.  The patch also adds one more whitespace after the
numeric EIP value.  The old dump looked this way:

  bad: scheduling while atomic!
  Stack: ffffffff c041c72f 0000006a 00000068 000000f0 c13e1f28 c04c49c0 c13e1f28
         c02a4099 c04c49c0 000000f0 00000000 00003104 c012592e 00003104 00003104
         ffffffff 34000286 00000282 00000000 00000000 c13e1f28 c04c49c0 c04c4468
  Call Trace:
   [<c011f009>]sys_gettimeofday+0x89/0x90
   [<c0113e40>]do_page_fault+0x0/0x49e
   [<c0107d63>]syscall_call+0x7/0xb

the new output is:

  bad: scheduling while atomic!
  Call Trace:
   [<c011f009>] sys_gettimeofday+0x89/0x90
   [<c0113e40>] do_page_fault+0x0/0x49e
   [<c0107d63>] syscall_call+0x7/0xb

much nicer and much more compact.