Re: udp6: Page fault panics

On 16.09.2018 03:04, Larry Rosenman wrote:
> vpanic() at vpanic+0x1a3/frame 0xfffffe00ca17c150
> panic() at panic+0x43/frame 0xfffffe00ca17c1b0
> trap_fatal() at trap_fatal+0x35f/frame 0xfffffe00ca17c200
> trap_pfault() at trap_pfault+0x49/frame 0xfffffe00ca17c260
> trap() at trap+0x2ba/frame 0xfffffe00ca17c370
> calltrap() at calltrap+0x8/frame 0xfffffe00ca17c370
> --- trap 0xc, rip = 0xffffffff80631428, rsp = 0xfffffe00ca17c440, rbp = 0xfffffe00ca17c480 ---
> selectroute() at selectroute+0x198/frame 0xfffffe00ca17c480
> in6_selectroute_fib() at in6_selectroute_fib+0xf/frame 0xfffffe00ca17c4a0
> ip6_output() at ip6_output+0xfd7/frame 0xfffffe00ca17c710

(kgdb) l *selectroute+0x198
0xffffffff80de14c8 is in selectroute
(/home/devel/freebsd/base/head/sys/netinet6/in6_src.c:736).
731		 * Use a cached route if it exists and is valid, else try to allocate
732		 * a new one.  Note that we should check the address family of the
733		 * cached destination, in case of sharing the cache with IPv4.
734		 */
735		if (ro) {
736			if (ro->ro_rt &&
737			    (!(ro->ro_rt->rt_flags & RTF_UP) ||
738			     ((struct sockaddr *)(&ro->ro_dst))->sa_family != AF_INET6 ||
739			     !IN6_ARE_ADDR_EQUAL(&satosin6(&ro->ro_dst)->sin6_addr,
740			     dst))) {

> calltrap() at calltrap+0x8/frame 0xfffffe00c9d863e0
> --- trap 0xc, rip = 0xffffffff80636b2b, rsp = 0xfffffe00c9d864b0, rbp = 0xfffffe00c9d86710 ---
> ip6_output() at ip6_output+0xeeb/frame 0xfffffe00c9d86710
> udp6_send() at udp6_send+0x720/frame 0xfffffe00c9d868d0
(kgdb) l *ip6_output+0xeeb
0xffffffff80de75bb is in ip6_output
(/home/devel/freebsd/base/head/sys/netinet6/ip6_output.c:531).
526		 */
527		if (inp) {
528			ro->ro_dst.sin6_family = AF_INET6;
529			RT_VALIDATE((struct route *)ro, &inp->inp_rt_cookie, fibnum);
530		}
531		if (ro->ro_rt && fwd_tag == NULL && (ro->ro_rt->rt_flags & RTF_UP) &&
532		    ro->ro_dst.sin6_family == AF_INET6 &&
533		    IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, &ip6->ip6_dst)) {
534			rt = ro->ro_rt;
535			ifp = ro->ro_rt->rt_ifp;

It looks like Ryan's assumption is correct and panics happen due to
several threads use the same PCB and then route cache invalidation happens.
https://lists.freebsd.org/pipermail/freebsd-net/2018-September/051563.html

But IPv6 path also needs similar patch.

-- 
WBR, Andrey V. Elsukov