if err := p.CheckValid(); err != nil {
			t.Fatalf("invalid profile: %v", err)
		}

		stks := stacks(p)
		for _, want := range [][]string{
			{"sync.(*Mutex).Unlock", "runtime/pprof.blockMutexN.func1"},
		} {
			if !containsStack(stks, want) {
				t.Errorf("No matching stack entry for %+v", want)
			}
		}

		i := 0
		for ; i < len(p.SampleType); i++ {

	if staticLockRanking {
		// When static lock ranking is enabled, we'll always be on the system
		// stack at this point. There will be a runtime.unlockWithRank.func1
		// frame, and if the call to runtime.unlock took place on a user stack
		// then there'll also be a runtime.systemstack frame. To keep stack
		// traces somewhat consistent whether or not static lock ranking is