malloc message with nfs transfer

malloc() of "64" with the following non-sleepable locks held:
exclusive sleep mutex inpr = 0 (0xc4444ef0) locked _at_ /usr/src/sys/netinet/udp_usrreq.c:378 
exclusive sleep mutex netisr lock r = 0 (0xc061be80) locked _at_ /usr/src/sys/net/netisr.c:215

I'm getting those on the console, and it seems that they only happen when 
users start an nfs transfer to the nfs exported filesystem.  The exported 
filesystem is a vinum raid5 array but I don't know if that has anything to 
do with the messages.

Before I upgraded from 4.8, I used to be able to send at about 8mb/s to the nfs exported raid5.  After upgrading to 5.1-CURRENT, the maximum speed has been only 4mb/s.  I'm wondering if the messages above have anything to do with the performance drop.