kernel: panic: softdep_sync_buf: Unknown type jnewblk

Jeremy Chadwick freebsd at
Fri Jan 27 01:54:31 UTC 2012

On Thu, Jan 26, 2012 at 05:32:06PM -0800, Doug Barton wrote:
> On 01/26/2012 16:40, Ant?nio Trindade wrote:
> > Cheers.
> > 
> > I recently updated my system to FreeBSD-9.0 and activated softupdate journaling for a number of file systems (name /home, /var, /usr).
> > 
> > Since then I have been experiencing kernel panics:
> > kernel: panic: softdep_sync_buf: Unknown type jnewblk
> > 
> > Yesterday, Jan 26th, I got 6 (six) automatic reboots due to these kernel panics.
> > 
> > I have now disabled softupdates journaling in the hope that the panics disappear.
> > 
> > I am sorry for not providing more information about the panic, but I'll gladly try to gather more info if instructed how to.
> Make sure that dumpdev is defined in rc.conf. Usually you want to use
> your swap device.
> You should also boot into single user mode and do 'fsck -y' to make sure
> that the file systems are actually clean. There have been problems
> reported where SU+J doesn't recover fully after a crash, which leads to
> the kinds of instability you're reporting.

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.

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.

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.

| 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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