10/amd64 lockup with lots of rpcbinds in fstchg

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

For the third time, one of our identical login servers (the same one each 
time) became unresponsive. Network is unresponsive, switching consoles with 
Ctl-Alt-Fn works, but they are unresponsive, entering DDB works. Last kernel 
message on screen is "in_chksum: out of data".
DDB reveals hundreds (thousands?) of rpcbind processes in fstchg state 
(whatever that is), as are several ssh processes, some cron and one ipmon 
one and ioflush. syslogd, ntpd and one icinga2 process is in tstile state. 
swapper is in uvm. The four active proceses seem to be four idle.

We never experienced that under 8; the other identical login sever has also 
been unaffected so far.

Does that ring a bell to someone?