POLLHUP detected on devd socket

Hi,

context is a usb3-booting rpi4 running main-n252544-7406ec4ea99

I see this in /var/log/daemon.log:

Jan 22 13:24:54 redacted zfsd[886]: POLLHUP detected on devd socket.
Jan 22 13:24:54 redacted zfsd[886]: Disconnecting from devd.
Jan 22 13:24:54 redacted zfsd[886]: ConnectToDevd: Connecting to devd.
Jan 22 13:24:54 redacted zfsd[886]: Unable to connect to devd
Jan 22 13:24:54 redacted zfsd[886]: Disconnecting from devd.

When this happens, several other things happen:

1. the sshd server dies. Already-established sessions still run, but 
    the server itself stops and no new ssh connections can be made.

2. syslogd dies. so does exim, nginx, smartd, sshguard, pf

I don't know where to start looking for reasons for this. Is it
a known issue? In the meantime I've turned off zfsd as it's not
really needed in this machine's context (headless, zfs on single
disk), from what I can tell.

-- 
J.