I have it too, after compiling kernel with debug info and spinlock witnessing. It does no harm, I guess...
I get THIS *every* time I exit X-windows:
lock order reversal
1st 0xc45f4b90 vm object (vm object) @ /usr/src/sys/vm/vm_object.c:432
2nd 0xc082f110 system map (system map) @ /usr/src/sys/vm/vm_kern.c:325
Stack backtrace:
backtrace(c057b35f,c082f110,c058cfb6,c058cfb6,c058ce51) at backtrace+0x17
witness_lock(c082f110,8,c058ce51,145,0) at witness_lock+0x697
_mtx_lock_flags(c082f110,0,c058ce51,145,3) at _mtx_lock_flags+0xb1
_vm_map_lock(c082f0b0,c058ce51,145,dcc91ab0,c0378eb4) at _vm_map_lock+0x36
kmem_malloc(c082f0b0,1000,101,dcc91b1c,c04c2cea) at kmem_malloc+0x39
page_alloc(c083a1c0,1000,dcc91b0f,101,c05f1a2c) at page_alloc+0x27
slab_zalloc(c083a1c0,101,c058e81a,664,c083a714) at slab_zalloc+0x14a
uma_zone_slab(c083a1c0,101,c058e81a,664,0) at uma_zone_slab+0xd8
uma_zalloc_internal(c083a1c0,0,101,6e8,0) at uma_zalloc_internal+0x55
uma_zfree_arg(c083a700,c4854cf0,0,dcc91bc8,c04a9d08) at uma_zfree_arg+0x2e7
dev_pager_putfake(c4854cf0,0,c058c5cf,be,c45f4b90) at dev_pager_putfake+0x3a
dev_pager_dealloc(c45f4b90,1,c058e71d,10c,0) at dev_pager_dealloc+0xc8
vm_pager_deallocate(c45f4b90,0,c058d8f3,25f,282c5000) at vm_pager_deallocate+0x3
d
vm_object_terminate(c45f4b90,0,c058d8f3,1b0,c45b44ec) at vm_object_terminate+0x1
f4
vm_object_deallocate(c45f4b90,c082cf00,c45f4b90,c082cf00,dcc91c9c) at vm_object_
deallocate+0x377
vm_map_entry_delete(c1528100,c082cf00,c058d024,8bc,c0576b6f) at vm_map_entry_del
ete+0x3b
vm_map_delete(c1528100,282c3000,282c5000,2000,282c3000) at vm_map_delete+0x3e3
vm_map_remove(c1528100,282c3000,282c5000,0,c4563618) at vm_map_remove+0x58
munmap(c4565130,dcc91d10,c0592c87,3fd,2) at munmap+0x9e
syscall(30002f,2f,bfbf002f,8201ad0,1) at syscall+0x26e
Xint0x80_syscall() at Xint0x80_syscall+0x1d
--- syscall (73), eip = 0x28230d83, esp = 0xbfbff9ec, ebp = 0xbfbffa08 --
smime.p7s
Description: S/MIME Cryptographic Signature
