[Bug 236220] ZFS vnode deadlock on zfs_mknode

[Ireneusz Pluta]

W dniu 2019-04-15 o 22:02, bugzilla-noreply at freebsd.org pisze:
> Unfortunately the likely way to get more
> traction with this problem is to have more Postgres+ZFS users upgrade to 12.0
> and report their findings.

so take me as +1.

I faced the same problem and found this thread pointing the cause.
In my case the quick resolution was easy: I could afford stepping back to 11.2.