I went to the dealer,
the problem was that the filter wasn't regenerating, and pieces of soot got into the engine oil. Now all is fixed (still under guarantee)
thanks.

I have a new Volvo cx90 (2010 model). After 8 months I received a notification : ENGINE SYSTEM SERVICE REQUIRED + SOOT FILTER FULL
LOOKING FOR ANYONE THAT ENCOUNTERED THE SAME PROBLEM AND KNOWS WHAT...