When multiple FreeBSD slices exist on one disk drive, fsck recognizes
each slice as separate disk drives. As a result, fsck -p checks each
slice concurrently. In addition, this causes kernel panic reported as
Fix: Following patch makes fsck's disk recognization algorithm properly.
Make multiple FreeBSD slices on one disk drive and describe these
slices in /etc/fstab.
Fixed in rev.1.8 of fsck/preen.c (-current).
Fixed in rev.188.8.131.52 of fsck/preen.c (2.2).