The Weeknd Starts Early ... for Khloe & French

12/10/2015 7:58 AM PST

It's true ... EVERYONE does love The Weeknd ... so much so, some celebs even risked bumping into an ex at The Forum in L.A. 

French Montana and Khloe Kardashian both entered through the VIP entrance ... at different times. Kendall Jenner was there too, and Jonas bros Nick and Joe brought their respective entourages.

Sources backstage at the show tell us Khloe and French hung out backstage and were completely cool with each other. We're told it was "all love."

Lana Del Rey made sure to stand out in the crowd -- even jumping onstage for a surprise performance  -- check out the gallery for her white on white on white outfit ... and all the other celeb fans of The Weeknd.