Re: nfs hang

Van: Rick Macklem <rick.macklem@gmail.com>
Datum: vrijdag, 14 november 2025 12:53
Aan: Mark Millard <marklmi@yahoo.com>
CC: Ronald Klop <ronald@freebsd.org>, freebsd-fs@freebsd.org
Onderwerp: Re: nfs hang
> 
> On Thu, Nov 13, 2025 at 4:51PM Mark Millard <marklmi@yahoo.com> wrote:
> >
> > Ronald Klop <ronald_at_FreeBSD.org> wrote on
> > Date: Thu, 13 Nov 2025 17:17:48 UTC :
> >
> > > Op 13-11-2025 om 14:06 schreef Rick Macklem:
> > > > On Thu, Nov 13, 2025 at 2:45AM Ronald Klop <ronald@freebsd.org> wrote:
> > > >>
> > > >> Op 13-11-2025 om 11:41 schreef Ronald Klop:
> > > >>> . . .
> > > >>>
> > > >>>
> > > >>
> > > >>
> > > >> . . .
> > > > Do you have more than one client mounting the file system?
> > > > If you do, make sure they all have different /etc/hostid's.
> > > > (Cloning a system disk without deleting /etc/hostid can
> > > > result in multiple clients with the same /etc/hostid. That
> > > > mean they are "the same client" to the NFSv4 server
> > > > and that can cause the above.)
> > > >
> > > > If this is not the problem, I don't know why you'd see the
> > > > above but I suspect the above explains the hang.
> > > >
> > > > rick
> > > >
> > >
> > >
> > > Two clients. Both have different /etc/hostid.
> > >
> > > I noticed that the procstat stacks start with "null_reclaim". And poudriere null-mounts the nfs mounts in the poudriere-jails.
> >
> > Do the poudriere jails on each host use the host's /etc/hostid (by content)?
> >
> > Any worries about needing poudriere jail /etc/hostid content uniqueness?
> From NFSv4's point of view, /etc/hostid is used at mount time.
> The client will use the one outside of any jail, since that is where the
> mount is done from.
> 
> Now, although I was thinking about the client (since that is where
> the hangs occur), it might be an issue if you were running the nfsd
> in multiple jails that have the same /etc/hostid as well.
> --> The server identifies itself to the client via the /etc/hostid and
>      a different identity means different server.
>      However, it could be a problem if the servers in different jails
>      return the "same server" from the same /etc/hostid.
> 
> I'll admit it as been years since I did the "run nfsd in a vnet jail"
> code and I don't remember if the use of /etc/hostid is vnet'd or
> not.
> 
> rick
> 
> >
> > > Could nfs+nullfs give some trouble? Or maybe it is just nullfs that hangs everything and the nfs stuff is just a result of it.
> > >
> > > At the same moment I had git hanging on a non-NFS mount. See attachment for the procstat which also includes nfs-calls.
> >
> > ===
> > Mark Millard
> > marklmi at yahoo.com
> >
> 
> 
> 


I only have 1 nfs server.
My vnet jail that runs nfsd does not have /etc/hostid.

/etc/rc.d/hostid and hostid_save have the keyword nojail so they never run inside a jail (AFAIK).
# sysctl kern.hostid
kern.hostid: 0

Is that an issue?

Regards,
Ronald.