Marijuana smell in apartment

I live in a Tang Lo in Sai Ying Pun and have been smelling weed in the halls for several weeks now. I'm personally all for legalization of marijuana, but the smell does bother me, and it has seeped into my apartment. I've spoken to my landlord and they said they will post a notice to warn whoever is smoking, but they have also asked me to report them to the police. Given the sentence in Hong Kong can be up to 7 years for possession , I'm quite reluctant to report the person, even if I knew who they were. I feel like the best case scenario is that the person stops or smokes less, or does better ventilation, so that I won't smell it so strongly, but I wonder if anyone knows what usually happens when someone is caught smoking weed? Is it as draconian as the maximum sentence suggests?