Will it be correct if I call instance method from the singleton's static method?

Question

I have example code on C++ that describes my solution:

#include <iostream>

class Singleton {
private:
    static Singleton* instance;
    Singleton() {
        std::cout << "Instance created" << std::endl;
    }
    Singleton(const Singleton&);
    Singleton& operator=(Singleton&);
public:
    static Singleton* getInstance();
    static void m1();
    void m2();
};

Singleton* Singleton::instance = 0;

Singleton* Singleton::getInstance() {
  if (!instance) {
        instance = new Singleton();
    }
    return instance;
}

void Singleton::m1() {
    std::cout << "Called m1" << std::endl;
    instance->m2();
}

void Singleton::m2() {
  std::cout << "Called m2" << std::endl;
}

int main() {
    Singleton* singleton = Singleton::getInstance();
    Singleton::m1();
    return 1;
}

Is it correct that I call instance method m2 from static method m1? Doesn't this cause any problems in maintaining and understanding the code, or would it be better to make m2 method also static?