panic: Duplicate free of item 0xffffff005c4a8600 from zone 0xffffff007fed4780(Mbuf)

[Willem Jan Withagen]

Starting on:

> - Try compiling IPv6 out of your kernel -- this will turn on the inpcb
>   locking assertions, which are compiled out by default because IPv4 and
>   IPv6 share the same underlying pcb code and IPv6 does not yet lock that
>   correctly in CVS.  I have patches that do quite a bit of that in
>   Perforce, and sent out an e-mail yesterday to the KAME folk to talk
>   about merging strategies.
> 
> - If this is a reproduceable problem, could you try disabling SACK and see
>   if it changes at all?

How do I disable SACK??
Probably there's a flag for, but which....

--WjW