[dm-devel] 4.4-rc4 multipath not working?

[E V]

Just tried booting 4.4-rc4 on a system with using the mptsas driver:
LSISAS3008: FWVersion(03.00.08.00), ChipRevision(0x02), BiosVersion(05.07.02.00)

And multipath doesn't seem to be working, dmesg has lots of these:

device-mapper: table: 254:2: multipath: unknown path selector type
device-mapper: ioctl: error adding target to table

Is it expected to work? and any suggestions on getting it to work,

Thanks,
-Eli