I rebooted and ran bt in the debugger and got this.
Tracing pid 59 tid 100115 td 0xc5fef2e0
get_disk_name(e8072b74,c0d04c5b,6e657662,c0de3600,8,...) at get_disk_name+0x11
hpt_status(c0de36e0,0,0,e8072b74,e8072b74,...) at hpt_status+0x8b8
sysctl_rooot(e8072b74,e8072b80,4,369e99,0,...) at...