page fault/panic: mi_switch: switch in a critical section

panic: page fault
panic messages:
---
Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0x104
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xc058a8cf
stack pointer           = 0x10:0xdcb34cc4
frame pointer           = 0x10:0xdcb34cec
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = resume, IOPL = 0
current process         = 50 (schedcpu)
trap number             = 12
panic: page fault

syncing disks, buffers remaining... panic: mi_switch: switch in a critical section

addr2line says the panic was in kern/sched_4bsd.c:327

                                /*
                                 * The kse slptimes are not touched in wakeup
                                 * because the thread may not HAVE a KSE.
                                 */
                                if (ke->ke_state == KES_ONRUNQ) {
                                        awake = 1;
                                        ke->ke_flags &= ~KEF_DIDRUN;
--->                            } else if ((ke->ke_state == KES_THREAD) &&
                                    (TD_IS_RUNNING(ke->ke_thread))) {
                                        awake = 1;

gdb -k got confused and couldn't make anything out of the backtrace.

Kris