Re: panic: Duplicate free of item 0xffffff005c4a8600 fromzone0xffffff007fed4780(Mbuf)

From: "Robert Watson" <rwatson_at_freebsd.org>
> On Mon, 19 Jul 2004, Willem Jan Withagen wrote:
>
> > > I'll starts some more tests before I'm of to bed.
> >
> > This mornings result:
> > ====
> > System call getdirentries returning with the following locks held:
> > exclusive sleep mutex bdone lock r = 0 (0xffffffff805fd080) locked _at_
/home2/src/
> > sys/kern/vfs_bio.c:3767
> > panic: witness_warn
> > cpuid = 0;
> > KDB: stack backtrace:
> > kdspin lock sched lock held by 0xffffff007b6cc940 for > 5 seconds
> > panic: spin lock held too long
> > cpuid = 0;
> > KDB: enter: panic
> > ====
> >
> > But no way to get into the debugger.  Does not look like it is much
> > network related???
>
> Doesn't look very network related, although it could be that increased
> concurrency and lack of waiting on Giant open up a race of some sort.  Can
> you confirm "options DDB" and "options KDB" are both in your kernel
> config?  You may want to consider commenting out "#define PREEMPTION" in
> the copy of params.h for the architecture you're running on and see if
> that helps.  Won't help interrupt processing latency, but probably won't
> hurt server throughput, and your box is a server box so it might be worth
> trying.

Well to box is actually just a toy in my office.... :)
And yes it is definitly disk-IO bound....

But I'll take PREEMPTION out if you want. have to think about doing it again it
when I cvsup again..

And yes, both DDB and KDB are in...
I'm also on the am64 list discussing the fact that 1 out of 3 times I do not get
a db> prompt.

# Debugging for use in -current
options         KDB                     # Enable kernel debugger support.
options         KDB_TRACE
options         DDB                     # Support DDB.
options         GDB                     # Support remote GDB.
options         INVARIANTS              # Enable calls of extra sanity checking
options         INVARIANT_SUPPORT       # Extra sanity checks of internal struct
options         WITNESS                 # Enable checks to detect deadlocks and
options         WITNESS_SKIPSPIN        # Don't run witness on spinlocks for spe

--WjW