D-Link DWA-556 atheros wireless card. ath_rx_proc: no mbuf! (fixed)
The D-Link DWA-556 is a PCIe draft-n wireless card.
I was getting plenty of these across the screen (2010-08-03 2.0 AMD64 snapshot): ath_rx_proc: no mbuf!
Associated with this message were dropped connections and pfsense freezes.
Like described, increased kern.ipc.nmbclusters from 0 to 65536 in /boot/loader.conf and all seems fine now.