lines := strings.Split(prof, "\n")
		if len(lines) < 6 {
			t.Fatalf("expected >=6 lines, got %d %q\n%s", len(lines), prof, prof)
		}
		// checking that the line is like "35258904 1 @ 0x48288d 0x47cd28 0x458931"
		r2 := `^\d+ \d+ @(?: 0x[[:xdigit:]]+)+`
		if ok, err := regexp.MatchString(r2, lines[3]); err != nil || !ok {
			t.Errorf("%q didn't match %q", lines[3], r2)
		}
		r3 := "^#.*runtime/pprof.blockMutex.*$"

	SHUT_RDWR                                   = 0x2
	SHUT_WR                                     = 0x1
	SIOCADDDLCI                                 = 0x8980
	SIOCADDMULTI                                = 0x8931
	SIOCADDRT                                   = 0x890b
	SIOCBONDCHANGEACTIVE                        = 0x8995
	SIOCBONDENSLAVE                             = 0x8990
	SIOCBONDINFOQUERY                           = 0x8994