panic: sbuf_trim makes no sense on sbuf 0xffffff82434d8898 with drain

Niclas Zeising zeising+freebsd at
Sun Nov 25 22:56:22 UTC 2012

On 11/25/12 23:48, mdf at wrote:
> On Sun, Nov 25, 2012 at 2:26 PM, Niclas Zeising
> <zeising+freebsd at>  wrote:
>> Hi!
>> I consistently get this panic while trying to boot a kernel build from
>> r243530.  It happens when the entropy harvesting rc.d script starts. r243380
>> worked fine, I haven't tested any revisions in between. Attached is the
>> backtrace from the kernel, as gotten by kgdb.  The machine uses zfs as a
>> root pool, and there have been churn in this area.  To my untrained eyes,
>> however, the issue seem related to hdaa.c. Please let me know if I can
>> provide any more information.
> r243530 added the new sysctl that is causing panic.  I'm not sure why
> there's an sbuf_trim() call; there shouldn't be more than a few \n at
> the end.  IMO the sbuf_trim() can be eliminated.
> Alternately, the panic check can be removed and we could allow
> sbuf_trim() to remove any un-emitted whitespace for an sbuf with
> drain.
> CC'ing mav@ who introduced the code.  (I introduced sbuf drains).

Thank you for the quick reply!
Just to confirm, manually reverting r243530 makes the system boot 
without panicing.

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