Date: Mon, 07 Nov 2011 08:18:26 -0800 From: Maxim Sobolev <sobomax@FreeBSD.org> To: "Bjoern A. Zeeb" <bz@FreeBSD.ORG>, Robert Watson <rwatson@FreeBSD.ORG>, "current@freebsd.org" <current@FreeBSD.ORG>, freebsd-net@FreeBSD.ORG Subject: Panic in the udp_input() under heavy load Message-ID: <4EB804D2.2090101@FreeBSD.org>
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Hi Gang,
We are seeing repeatable panics under high PPS load on our production
systems. It happens when the traffic gets into the range or 200MBps and
150-200K PPS. We have been managed to track it down to the following
piece of code:
(gdb) l *udp_input+0x5d2
0xffffffff806f6202 is in udp_input (/usr/src/sys/netinet/udp_usrreq.c:628).
623 if (inp->inp_ip_minttl && inp->inp_ip_minttl > ip->ip_ttl) {
624 INP_RUNLOCK(inp);
625 goto badunlocked;
626 }
627 up = intoudpcb(inp);
628 if (up->u_tun_func == NULL) {
629 udp_append(inp, ip, m, iphlen + sizeof(struct
udphdr), &udp_in);
630 } else {
631 /*
632 * Engage the tunneling protocol.
The faulty line appears to be 628, with up value is being NULL, attempt
to deference it causes NULL pointer exception. I believe this particular
piece of code has been introduced here:
---
Author: bz
Date: Thu Aug 13 15:16:30 2009
New Revision: 196192
URL: http://svn.freebsd.org/changeset/base/196192
Log:
MFC: r192649
Implement UDP control block support.
Add udpcb support with own fields and flags for UDP instead
of further sticking things into in_pcb and flags fields.
Attach the udpcb to the inp_ppcb in the kernel.
Note: the udp tunneling parts are not (yet) existing in 7
and thus were not merged.
Reviewed by: rwatson
---
The screenshot of the panic message is attached. This is pretty recent
8.2-STABLE. Any help is greatly appreciated. This particular bug has
haunted us for at least 4-5 months now.
Thanks!
-Maxim
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