11.0-CURRENT r290039 privileged instruction fault while in kernel mode

I just got this crash while running poudriere on a freshly upgraded
11.0-CURRENT machine.  The instruction pointer value looks pretty
strange.


FreeBSD zipper.catspoiler.org 11.0-CURRENT FreeBSD 11.0-CURRENT #30 r290039: Tue Oct 27 00:08:00 PDT 2015     dl_at_zipper.catspoiler.org:/usr/obj/usr/src/sys/GENERIC  amd64

panic: 

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Unread portion of the kernel message buffer:


Fatal trap 1: privileged instruction fault while in kernel mode
cpuid = 4; apic id = 14
instruction pointer	= 0x20:0xffffffff8240fef5
stack pointer	        = 0x28:0xfffffe0859c636c0
frame pointer	        = 0x28:0xfffffe0859c636e0
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 0 (zio_free_issue_2_9)

Reading symbols from /boot/kernel/zfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/zfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/zfs.ko
Reading symbols from /boot/kernel/opensolaris.ko...Reading symbols from /usr/lib/debug//boot/kernel/opensolaris.ko.debug...done.
done.
Loaded symbols for /boot/kernel/opensolaris.ko
Reading symbols from /boot/kernel/geom_mirror.ko...Reading symbols from /usr/lib/debug//boot/kernel/geom_mirror.ko.debug...done.
done.
Loaded symbols for /boot/kernel/geom_mirror.ko
Reading symbols from /boot/modules/vboxdrv.ko...done.
Loaded symbols for /boot/modules/vboxdrv.ko
Reading symbols from /boot/modules/vboxnetflt.ko...done.
Loaded symbols for /boot/modules/vboxnetflt.ko
Reading symbols from /boot/kernel/netgraph.ko...Reading symbols from /usr/lib/debug//boot/kernel/netgraph.ko.debug...done.
done.
Loaded symbols for /boot/kernel/netgraph.ko
Reading symbols from /boot/kernel/ng_ether.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_ether.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_ether.ko
Reading symbols from /boot/modules/vboxnetadp.ko...done.
Loaded symbols for /boot/modules/vboxnetadp.ko
Reading symbols from /boot/kernel/nullfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/nullfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/nullfs.ko
Reading symbols from /boot/kernel/linux.ko...Reading symbols from /usr/lib/debug//boot/kernel/linux.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linux.ko
Reading symbols from /boot/kernel/linux_common.ko...Reading symbols from /usr/lib/debug//boot/kernel/linux_common.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linux_common.ko
Reading symbols from /boot/kernel/linprocfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/linprocfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linprocfs.ko
Reading symbols from /boot/kernel/tmpfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/tmpfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/tmpfs.ko
Reading symbols from /boot/kernel/fdescfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/fdescfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/fdescfs.ko
#0  doadump (textdump=0) at pcpu.h:221
221	pcpu.h: No such file or directory.
	in pcpu.h
(kgdb) #0  doadump (textdump=0) at pcpu.h:221
#1  0xffffffff8037c6b6 in db_fncall (dummy1=<value optimized out>, 
    dummy2=<value optimized out>, dummy3=<value optimized out>, 
    dummy4=<value optimized out>) at /usr/src/sys/ddb/db_command.c:568
#2  0xffffffff8037c14e in db_command (cmd_table=0x0)
    at /usr/src/sys/ddb/db_command.c:440
#3  0xffffffff8037bee4 in db_command_loop ()
    at /usr/src/sys/ddb/db_command.c:493
#4  0xffffffff8037e97b in db_trap (type=<value optimized out>, code=0)
    at /usr/src/sys/ddb/db_main.c:251
#5  0xffffffff80a5fc73 in kdb_trap (type=1, code=0, tf=<value optimized out>)
    at /usr/src/sys/kern/subr_kdb.c:654
#6  0xffffffff80e69c81 in trap_fatal (frame=0xfffffe0859c63610, 
    eva=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:829
#7  0xffffffff80e69951 in trap (frame=<value optimized out>)
    at /usr/src/sys/amd64/amd64/trap.c:203
#8  0xffffffff80e498d7 in calltrap ()
    at /usr/src/sys/amd64/amd64/exception.S:234
#9  0xffffffff8240fef5 in cpu_lock () from /boot/kernel/opensolaris.ko
#10 0xfffff804aaeb8000 in ?? ()
#11 0x0000000000000001 in ?? ()
#12 0xfffffe0859c63760 in ?? ()
#13 0xffffffff82125325 in vdev_mirror_io_start (zio=0xfffff8047a6d9000)
    at /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_mirror.c:475
Previous frame identical to this frame (corrupt stack?)
Current language:  auto; currently minimal
(kgdb)