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

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.
Not saying this is what you are seeing, but one possible explanation is that
the client is running out of reserved port#s.
If that happens, it is stuck between a rock and a hard place.

rick

>
> Best regards,
> Andreas Kempe
>