dlmgtd process deadlocks.
When performing the dlmgmt_zonehalt door command, a global write lock is held across a system call. The system call then performs a door_upcall back to the dlmgmtd process which tries to acquire a read lock.
Which results in a deadlock. But only occasionally.
I have a core dump of the dlmgmt process, but it is over 4 Mb so I can't attach it.
Attached is a set of mdv commands I ran to debug the issue.