Malia Obama Rocks, at Lollapalooza

Malia Obama was feeling the music so much she couldn't contain herself ... so she writhed around on the ground in rock 'n' roll euphoria.

Barack's oldest daughter let her hair down in Chicago Friday night at Lollapalooza ... but especially while The Killers were playing.

And dance she did ... and headbang ... and roll around in the grass.

UCJ, UNILORIN.