'Celeb Rehab' Star Back In The Slammer

4/29/2011 6:01 AM PDT

'Celeb Rehab' Star -- Back In The Slammer

"Celebrity Rehab" star Frankie Lons -- the mother of singer Keyshia Cole -- is back in jail this morning ... after cops say they found her in possession of "drug-related material" ... TMZ has learned.

Law enforcement tells us ... cops stopped Frankie for a routine traffic violation yesterday when they noticed an active warrant out for her arrest stemming from a probation violation. 

We're told cops then performed a search -- and found "drug-related material" on her person.

Lons was arrested and transported to a nearby jail -- where she was booked for the probation violation and misdemeanor possession of drug-related material.

This morning, Lons is still in custody.