Impreza diesel self revs to max/white smoke

[Imcata]

Hi,
Maybe i can find someone who experienced similar issue:
- car in discussion: Impreza Diesel 2.0D, 2009
- started my car ok, drive for ~ 10 km, then noticed that i could not get above 2500 rpm
- when I pressed the clutch, engine stopped
- I could not re-start it for several attempts (Battery ok, starter worked, looked like it was about to start but then stalls)
- no check light, nothing on the OBD reader
- eventually managed to start (not doing anything different, just waited for a while on the side of the road)
- i was able to raise above 2500 rpm, but the car was vibrating a lot
- at a random moment, it started to rev to maximum by itself (>5500 rpm) . Could not stop it manually, but it did stop after an error occurred for “rpm exceed”
- while having the high revs, there was also a lot of white smoke coming from the exhaust.
- I did not restart it after this event.

I read some threads, some would blame the crankshaft sensor (was not able to find its location until now), some blame the turbo having leaks/shaft broken, some blame the high pressure injection pump.

Any of you had similar experience? What could be the blame for this?

Many thanks in advance