Re: 9.0-RC1 panic in tcp_input: negative winow.

On Sun, Oct 23, 2011 at 08:10:38AM +0200, Pawel Jakub Dawidek wrote:
> On Sun, Oct 23, 2011 at 12:35:15PM +1100, Lawrence Stewart wrote:
> > On 10/22/11 19:49, Pawel Jakub Dawidek wrote:
> > > The panic message says:
> > >
> > > 	panic: tcp_input negative window: tp 0xfffffe007763e000 rcv_nxt 3718269252 rcv_adv 3718268291
> > >
> > > I only have picture of the backtrace:
> > >
> > > 	http://people.freebsd.org/~pjd/misc/panic_negative_window.jpg
> > >
> > 
> > ewww that is not good. Can you give us any more information about the 
> > machine and what it's doing? Is it terminating TCP connections from the 
> > internet at large or only local LAN (i.e. is there likely to be packet 
> > loss happening)? Are you doing TSO or LRO? Do you have any non-default 
> > tuning in place?
> 
> It is my local file server. It is doing NFS and AFP over LAN and also
> downloads files from the internet. It is triggered after few hours.
> I changed the KASSERT() into printf() and added printing 'win' variable
> and this is what got logged during the night:
> 
> 05:16:24 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1107827269 rcv_adv 1107826256 win=242
> 05:16:29 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1107833451 rcv_adv 1107832977 win=880
> 05:16:41 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1107849563 rcv_adv 1107848860 win=639
> 05:20:02 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108108230 rcv_adv 1108107331 win=567
> 05:24:30 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108433302 rcv_adv 1108432272 win=974
> 05:24:46 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108450385 rcv_adv 1108450060 win=751
> 05:26:44 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108574818 rcv_adv 1108573851 win=71
> 05:28:03 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108654103 rcv_adv 1108653166 win=0
> 05:28:43 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108692396 rcv_adv 1108691451 win=0
> 05:30:06 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1108781258 rcv_adv 1108780372 win=235
> 05:35:05 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1109067578 rcv_adv 1109067335 win=663
> 05:37:03 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1109180403 rcv_adv 1109179411 win=0
> 05:41:03 tcp_input negative window: tp 0xfffffe0026772b70 rcv_nxt 1109428265 rcv_adv 1109427375 win=170
> 
> And the systems seems to be fine.
> 
> I'm happy to test patches, but one round would take 24h.
> 
> My suggestion would be that if we won't be able to fix it before 9.0,
> we should turn this assertion off, as the system seems to be able to
> recover.

Shipped kernels have all assertions turned off.