little confuse about kernel trace point

[ch huang]

i see the following code in example script


probe kernel.trace("mm_pdflush_kupdate") {
  if (!log_event()) next
  kupdate[pid()] <<< $count
  command[pid()] = execname()
}

so when i search "mm_pdflush_kupdate" i find something about trace
point define named mm_pdflush_kupdate

in file include/trace/mm.h

 62 DEFINE_TRACE(mm_pdflush_kupdate,
 63     TPPROTO(unsigned long count),
 64     TPARGS(count));

it seems mm_pdflush_kupdate trace a variable in kernel code,but how
can i find exactly name ? and in which function?