Malaysia has a multiple-entry visa for one year.

First of all, the multiple-entry visa is applicable to those who have entered China for a short stay, but it is not applicable to those who use this visa for a long stay. Therefore, in principle, it is allowed to re-enter Malaysia after staying in Malaysia for 30 days at a time. However, officials of the border immigration control office have the right to refuse passengers entry. In fact, many people who hold such visas and re-enter Malaysia within a short time after leaving the country are refused entry. It doesn't matter whether you go to neighboring countries or go back to China after leaving the country. It is important not to re-enter Malaysia in a short time. According to my experience, you can't stay in Malaysia longer than when you are not in Malaysia, otherwise you will easily be refused entry. One exception is that if you can find a special relationship, that's another matter. Everyone knows that the corruption of the government of country X is world-famous. As for whether to show a return ticket every time you enter the country, it depends on the happiness of the immigration officials. Usually, this is necessary, some of which depend on the amount of cash you have with you.