LOR on mounting root

I've renewed -current yesterday and got LOR on mounting root:
(These is no com-port on my IBM T43 notebook so I'll type by hands)

Trying to mount root from ufs:/dev/ad0s1
lock over reversal:
 1st 0xc22960a8 pmap (pmap) _at_ /usr/src/sys/i386/i386/pmap.c:2111
 2st 0xc104c078 system map (system map) _at_ /usr/src/sys/vm/vm_map.c:1096
KDB: stack backtrace:
kdb_backtrace(c0736539,c104c078,c0749c86,c0749c86,c074a1ce) at
kdb_backtrace+0x2e
witness_checkorder(c104c078,9,c074a1ce,448,e0d7c990) at
witness_checkorder+0x6d1
_mtx_lock_flags(c104c078,c074a1ce,448,bfeff000) at _mtmx_lock_flags+0x92
_vm_map_lock(x104c000,c074a1ce,448,c055dd01,c0796590) at _vm_map_lock+0x34
vm_map_find(c104c000,0,0,0,e0d7ca0c) at vm_map_find+0x3d
kmem_alloc_nofault(c104c000,1000,c0750dc4,65c,0) at kmem_alloc_nofault+0x69
get_pv_entry(c22960a0,0,c0750dc4,6cb,0) at get_pv_entry+0x12b
pmap_insert_entry(c22960a8,bfbff000,c1e72cf8,83f,0) at
pmap_insert_entry+0x62
pmap_enter(c22960a8,bfbff000,c1e72cf8,7,0) at pmap_enter+0x25c
vm_fault(c2296000,bfbff000,2,8,c228d360) at vm_fault+0x14c5
trap_pfault(e0d7cc64,0,bfbffff,c074a1ce,bfbffff) at trap_pfault+0xed
trap(e0d70008,c06a0028,c2290028,c076b84a,bfbffff) at trap+0x40d
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc06aa025, esp = 0xe0d7cca4, ebp = 0xe0d7cd00 ---
subyte(0,e0d7cd38,c072f1aa,32b,0) at subyte+0x25
fork_exit(c0510250,0,e07cd38) at fork_exit+0xc3
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xe0d7cd6c, ebp = 0 ---
panic: _mtx_lock_sleep: recursed on non-recursive mutex pmap _at_
/usr/src/sys/i386/i386/pmap.c:1843

KDB: enter: panic
[thread pid 1 tid 100007 ]
Stopped at     kdb_enter+0x30: leave
db>

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Sem.
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Sem.