System hang on shutdown when running freebsd-update

[Kevin Oberman]

On Tue, Oct 28, 2014 at 3:09 PM, Walter Hop <freebsd at spam.lifeforms.nl>
wrote:

> [Apologies for not replying directly to the thread; I found it at
> https://lists.freebsd.org/pipermail/freebsd-stable/2014-October/080595.html
> ]
>
> I noticed this same hang after upgrading from 10.0-RELEASE to 10.1-RC3 in
> a VM running under VMware Fusion, so the problem appears still present.
>
> I could only make it happen in the single uptime just after the system was
> freebsd-updated from FreeBSD 10.0 to 10.1-RC3.
>
> Here is a screenshot: http://lf.ms/wait-for-reboot.png
>
> It did not make any progress after 2 hours of waiting. When restarting the
> VM, the disk was dirty.
>
> Some interesting facts:
> - Note "swapoff: /dev/da0p2: Cannot allocate memory" in the screenshot
> which might pose a clue. I haven’t seen this normally.
> - FreeBSD does respond to ping while it is busy, so it is not a complete
> "freeze".
> - The VM is at 100% CPU while this is going on.
>
> I have created a snapshot of the VM in the failed state, so maybe some
> useful information could be retrieved from it, although I don’t have any
> experience with kernel debugging over VMware.
>
> Cheers,
> WH
>
> --
> Walter Hop | PGP key: https://lifeforms.nl/pgp
>
> I am starting to suspect that some code that is needed to flush a resource
that is blocking the complete shutdown is no longer available so waiting is
not going to work. I tried a simple "shutdown now" and waited in single
user mode for a minute before "reboot". It worked fine.

This is based on guesswork, but seems to fit the symptoms.
--
R. Kevin Oberman, Network Engineer, Retired
E-mail: rkoberman at gmail.com