iSCSI initiator: iscontrol cannot be stopped or killed

Problem: the iscontrol process starts normally and establishes
a session and brings up a device, but it cannot be stopped.
It does not react to a HUP signal, and neither to KILL.

The /dev/da0 device is operational and the remote disk remains
normally accessible, regardless of how I try to (unsuccessfully)
shutdown the iscontrol process. The ps reports the state of the
process as "Ds", not doing anything. A ktrace does not show any
reaction to a received signal. A restart seems to be necessary
to break the iSCSI session.

Using FreeBSD 9.0-rc2, amd64, also tried with 9.0-PRERELEASE
(csup tag=RELENG_9 as of today).  This used to work normally
as documented on the same host with the same iscsi.conf
config file before upgrading from 8.2 to 9.0.

Anybody else experiencing this problem? Suggestions welcome.

  Mark