in trace/postprocess/trace-vmscan-postprocess.pl [229:243]
sub read_statline($) {
my $pid = $_[0];
my $statline;
if (open(STAT, "/proc/$pid/stat")) {
$statline = <STAT>;
close(STAT);
}
if ($statline eq '') {
$statline = "-1 (UNKNOWN_PROCESS_NAME) R 0";
}
return $statline;
}