foo m 1 m 2 m 3 m 4 bar
foo m 2 m 4 m 7 bar
foo m 1 bar

##</code><code>##

my (@match) = ($str =~ /^foo (?:m (\d+) )+bar/);

##</code><code>##

my @match;
if ($str =~ /^foo /) {
    while ($str =~ /m (\d+) /g) {
        push @match, $1;
    }
}