Justin Bieber just got back to the U.S.A. and he’s already got police pounding on his front door — for throwing one of his trademark Beverly Hills all-nighters. According to law enforcement sources … Bev Hills P.D. went to Bieber’s condo TWICE last night to deal with noise complaints. The first visit was shortly after 11 P.M. … but when officers arrived they didn’t hear anything, so they left without knocking.The second time — around 12:40A.M. — there was noise … we’re told around 30-40 people were milling around Bieber’s balcony. Cops knocked on the door, and spoke directly to Justin … reminding him his neighbors could make a citizen’s arrest if the noise continued, but Justin was cooperative and agreed to break up the party.As we first told you … JBwas supposed to be out of this building at the end of September, but he’s been traveling around Europe for several weeks… and hasn’t found a new pad yet. Enjoy him while you can, Beverly Hills.If at all youre enjoying.