kernel: panic: softdep_sync_buf: Unknown type jnewblk

Yamagi Burmeister lists at
Fri Jan 27 08:39:47 UTC 2012

Hi :)

On Thu, 26 Jan 2012 17:54:30 -0800
Jeremy Chadwick <freebsd at> wrote:

> I'll also point out, though the OP isn't using snapshots, that it's
> confirmed use of snapshots on SU+J can result in a full filesystem hang.
> Confirmation is from Kirk McKusick (author of SU and designer of SU+J):
> Something really needs to be done about this combination of problems.
> Since SU+J is the default choice for all UFS filesystems on 9.0-RELEASE,
> the only solution I can think of is to send a massive announcement to
> relevant mailing lists, AND put something on the home page
> about these issues.

The problem was analyzed but no immediate solution found. Therefor
snapshots on filesystems with SU+J (but not SU alone) were disabled
by Kirk McKusick in SVN r230250. The MFC to 9-STABLE has still to
be done. Maybe this fix is a candidate for an errata notice / patch,
distributed by freebsd-update?

> For the snapshot issue, I believe not using SU+J (and only SU) works
> around the problem, so possibly that would be the best choice of
> recommendation at this time.

Yes, snapshots with SU alone are working.

> I urge key members of the community and (as always) kernel developers to
> chime in here with advice.  Something needs to be done, users need to be
> made aware of these problems, and so on.

Due to lack of time and not being the author of the rather complex code
Kirk McKusick was not able to fix the problem. We're now waiting for
Jeff Roberson to step up, but I was told that he is very busy and has
no time too.

> -- 
> | Jeremy Chadwick                                 jdc at |
> | Parodius Networking            |
> | UNIX Systems Administrator                 Mountain View, CA, US |
> | Making life hard for others since 1977.             PGP 4BD6C0CB |
> _______________________________________________
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XMPP:      yamagi at
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