panic: blockable sleep lock (sleep mutex) Giant _at_ kern/kern_intr.c:661

Updated to -current, panicked at boot:

Timecounters tick evpanic: blockable sleep lock (sleep mutex) Giant _at_ kern/kern_intr.c:661
cpuid = 0
KDB: enter: panic
[thread pid 30 tid 100035 ]
Stopped at      kdb_enter+0x30: leave
db> wh
Tracing pid 30 tid 100035 td 0xcc5b7bd0
kdb_enter(c072c0f6,0,c07303fc,f5893c50,cc5b7bd0) at kdb_enter+0x30
panic(c07303fc,c074362d,c073e0e1,c07294ca,295) at panic+0x13f
witness_checkorder(c07939e8,9,c07294ca,295,c07999f8) at witness_checkorder+0xd6
_mtx_lock_flags(c07939e8,0,c07294c1,295,2) at _mtx_lock_flags+0x94
ithread_execute_handlers(cc5c1000,cc5f8c80,c052b648,c07939d0,cc5b7bd0) at ithread_execute_handlers+0x10c
ithread_loop(cc5d3440,f5893d38,c07292b7,31a,cc5d3440) at ithread_loop+0x78
fork_exit(c051d959,cc5d3440,f5893d38) at fork_exit+0xc5
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xf5893d6c, ebp = 0 ---

db> ps
  pid   proc     uid  ppid  pgrp  flag   stat  wmesg    wchan  cmd
   30 cc5c1000    0     0     0 0000204 [CPU 0] swi0: sio
   29 cc5c1234    0     0     0 0000204 [IWAIT] irq1: atkbd0
   28 cc5c1468    0     0     0 0000204 [RUNQ] fdc0
   27 cc4cc69c    0     0     0 0000204 [IWAIT] irq15: ata1
   26 cc4cc8d0    0     0     0 0000204 [IWAIT] irq14: ata0
   25 cc4ccb04    0     0     0 0000204 [IWAIT] irq18: fxp1
   24 cc4ccd38    0     0     0 0000204 [IWAIT] irq17: fxp0
   23 cc531000    0     0     0 0000204 [RUNQ] aic_recovery1
   22 cc531234    0     0     0 0000204 [IWAIT] irq77: ahc1
    9 cc531468    0     0     0 0000204 [RUNQ] aic_recovery1
    8 cc53169c    0     0     0 0000204 [RUNQ] aic_recovery0
   21 cc5318d0    0     0     0 0000204 [IWAIT] irq76: ahc0
    7 cc531b04    0     0     0 0000204 [RUNQ] aic_recovery0
   20 cc47e234    0     0     0 0000204 [IWAIT] swi2: cambio
   19 cc47e468    0     0     0 0000204 [IWAIT] swi5: +
    6 cc47e69c    0     0     0 0000204 [RUNQ] thread taskq
   18 cc47e8d0    0     0     0 0000204 [IWAIT] swi6: Giant taskq
   17 cc47eb04    0     0     0 0000204 [IWAIT] swi6: task queue
    5 cc47ed38    0     0     0 0000204 [RUNQ] kqueue taskq
   16 cc4cc000    0     0     0 0000204 [RUNQ] yarrow
    4 cc4cc234    0     0     0 0000204 [RUNQ] g_down
    3 cc4cc468    0     0     0 0000204 [RUNQ] g_up
    2 cc479000    0     0     0 0000204 [RUNQ] g_event
   15 cc479234    0     0     0 0000204 [IWAIT] swi1: net
   14 cc479468    0     0     0 0000204 [IWAIT] swi3: vm
   13 cc47969c    0     0     0 000020c [RUNQ] swi4: clock sio
   12 cc4798d0    0     0     0 000020c [Can run] idle: cpu0
   11 cc479b04    0     0     0 000020c [Can run] idle: cpu1
    1 cc479d38    0     0     0 0000200 [INACTIVE] swapper
   10 cc47e000    0     0     0 0000204 [RUNQ] audit_worker
    0 c0792020    0     0     0 0000200 [RUNQ] swapper
db> show alllocks
Process 0 () thread 0xc0792258 (0)
exclusive sleep mutex Giant r = 0 (0xc07939e8) locked _at_ vm/vm_contig.c:583

Kris