acquiring duplicate lock of same type: "network driver"

Hi,

Witness reports this on a recent -current box (2 days old) doing nat
with pf :

acquiring duplicate lock of same type: "network driver"
 1st nv0 _at_ /usr/ports/net/nvnet/work/nvnet/module/../src/if_nv.c:1511
 2nd skc0 _at_ /usr/src/sys/modules/sk/../../pci/if_sk.c:1112
KDB: stack backtrace:
witness_checkorder(c2855c44,9,c07316ba,458) at witness_checkorder+0x500
_mtx_lock_flags(c2855c44,0,c07316ba,458,c2ac4e00) at _mtx_lock_flags+0x40
sk_jfree(e5a44340,c28e3000,0,c2857c00,e3c79c80) at sk_jfree+0x33
mb_free_ext(c2ac4e00) at mb_free_ext+0x36
m_freem(c2ac4e00,c2857c00,e5901000,e56fb0e0,c2857e60) at m_freem+0x21
nv_ospackettx(c2857c00,e56fb0e0,1,e5901000,0) at nv_ospackettx+0x73
UpdateTransmitDescRingData() at UpdateTransmitDescRingData+0xd3

(it probably happened before but I didn't have witness enabled)
This could perhaps deadlock a box with 2 sk(4) interfaces...

Cheers,

Antoine