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

On Sunday, December 25, 2011 11:01:33 am Коньков Евгений wrote:
> Здравствуйте, John.
> 
> Вы писали 20 декабря 2011 г., 16:52:44:
> 
> JB> On Saturday, December 17, 2011 6:21:27 pm Pawel Jakub Dawidek wrote:
> >> On Mon, Dec 12, 2011 at 11:00:23AM -0500, John Baldwin wrote:
> >> > An update.  I've sent Pawel a testing patch to see if my hypothesis is correct
> >> > (www.freebsd.org/~jhb/patches/tcp_negwin_test.patch).  If it is then I intend
> >> > to commit www.freebsd.org/~jhb/patches/tcp_negwin2.patch as the fix.
> >> 
> >> Unfortunately it paniced today. Take a look at:
> >> 
> >>       http://people.freebsd.org/~pjd/misc/tcp_panic.jpg
> 
> JB> Ok, the one use case I was worried about is happening regularly before your
> JB> panic, so that is good.  Can you use gdb to figure out which call to
> JB> tcp_output() is actually panic'ing?  I wonder if it is this case:
> 
> JB>         /*
> JB>          * Return any desired output.
> JB>          */
> JB>         if (needoutput || (tp->t_flags & TF_ACKNOW)) {
> JB>                 (void) tcp_output(tp);
> JB>                 /* XXX: Debug */
> JB>                 KASSERT(SEQ_GEQ(tp->rcv_adv, tp->rcv_nxt),
> JB>                     ("tcp_input: negative window after ACK"));
> 
> JB> And if 'needoutput' is true, but TF_ACKNOW is not set, and tcp_output() decides
> JB> to not do anything.  I've updated tcp_negwin_test.patch to not panic if that call
> JB> to tcp_output() doesn't actually send a packet.  Please re-test.
> 
> 
> # uname -a
> FreeBSD meta-up 9.0-PRERELEASE FreeBSD 9.0-PRERELEASE #4: Sat Dec 24 13:59:20 EET 2011     _at_:/usr/obj/usr/src/sys/KES_KERN_v10  i386
> 
> rebooting once per day. Now I compile kernel with debug options.
> Can you advice me which and where I find debug info when it will
> reboting next time? so I can help to debug problem

Are you using the patch at the URL above (tcp_negwin_test.patch)?  If not,
can you try applying that patch and seeing if you still get any panics?

-- 
John Baldwin