How can I clear active NFS client-side server/volume entries that have become disassociated with any mounted filesystems? [duplicate]

Question

I have a situation where server-side mountpoints sometimes don't show up over NFS with a certain glitchy server. Typically restarting nfsd and/or fiddling with /etc/exports fixes things, but today this technique made everything worse: the client got into a state where it has an active (stuck?) connection to the NFS server in the kernel, but no mounts.

I think the active connection is keeping the broken server view in the client's memory. I want to completely disconnect the client so I can remount from scratch.

Here's the client's view of the server right now:

# cat /proc/fs/nfsfs/servers 
NV SERVER   PORT USE HOSTNAME
v4 c0a80002  801   1 192.168.0.2

# cat /proc/fs/nfsfs/volumes 
NV SERVER   PORT DEV          FSID                              FSC
v4 c0a80002  801 0:24         440f01c0e0f340b5:b7d3a2c45abef647 no 

In the interests of completeness, the following is unredacted:

# cat /proc/mounts 
/dev/root / ext4 rw,relatime,data=ordered 0 0
devtmpfs /dev devtmpfs rw,relatime,size=1028128k,nr_inodes=217391,mode=755 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
tmpfs /run tmpfs rw,relatime,mode=755 0 0
devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
none /dev/shm tmpfs rw,relatime 0 0
cgroup /sys/fs/cgroup cgroup rw,relatime,cpuset,cpu,cpuacct,blkio,memory,devices,freezer,net_cls,perf_event,net_prio,pids 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
none /dev/shm tmpfs rw,relatime 0 0
none /sys/kernel/debug debugfs rw,relatime 0 0

So there you go: an NFS connection, without any mounts.

My question:

I want to run a nuclear steam roller over the client's NFS configuration so I can start again — but without rebooting. What can I do?