Re: Automount + NFS hang issues (follow-up to FreeBSD 12.3/13.1 NFS client hang thread)

On Sun, Apr 14, 2024 at 12:20:36PM -0700, Rick Macklem wrote:
> On Sun, Apr 14, 2024 at 8:48 AM Andreas Kempe <kempe@lysator.liu.se> wrote:
> >
> > Hello,
> >
> > I'm doing a follow-up on the thread FreeBSD 12.3/13.1 NFS client hang,
> > message ID YpEwxdGCouUUFHiE@shipon.lysator.liu.se.
> >
> > After having had recurring issues ever since that thread and not
> > managing a good tcpdump of a hang, I decided to simply get rid of
> > automount and instead mount the NFS shares via the fstab. With the
> > mounts being done via the fstab instead of automount, the NFS server
> > restarting causes processes using the mount to hang, but when the
> > server comes back things recover.
> >
> > When using automount as the NFS server becomes unresponsive, the
> > system log is filled with lines like
> >
> >    7 Apr 10 13:00:14 shipon kernel: WARNING: autofs_trigger_one: request for /home/ completed with error 60, pid 68836 (fish)
> >    8 Apr 10 13:00:14 shipon kernel: WARNING: autofs_trigger_one: request for /home/ completed with error 60, pid 69248 (sshd)
> >    9 Apr 10 13:00:14 shipon kernel: WARNING: autofs_trigger_one: request for /home/ completed with error 60, pid 2221 (weechat)
> >
> > and it seems like automount is repeatedly trying to perform mounts
> > until the system eventually hangs. When the system has hung, all
> > automount processes are stuck in the kernel in uninterruptable sleep
> > in the NFS code. You can find some stack traces in the old thread.
> > Sometimes a umount -N on all the mounts would solve the issue, but
> > often a system reboot was the only way to recover.
> I might take another look, but I have never been involved in the automount code
> and never use the automounter, so I doubt I'll figure out how to fix it.
> 

No pressure to have a look for our sake. Mounting from the fstab works
for us for the forseeable future. I mostly thought I'd report it for
posterity and anyone else encountering the same issue.

// Andreas Kempe