Date: Wed, 22 Jul 2020 12:34:43 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Peter Libassi <peter@libassi.se>, Marko Zec <zec@fer.hr>, freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: somewhat reproducable vimage panic Message-ID: <20200722193443.GG4213@funkthat.com> In-Reply-To: <20200722060514.GF4213@funkthat.com> References: <20200721091654.GC4213@funkthat.com> <20200721113153.42d83119@x23> <20200721202323.GE4213@funkthat.com> <38F5A3A6-B578-4BA4-8F69-C248163CB6E0@libassi.se> <20200722060514.GF4213@funkthat.com>
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John-Mark Gurney wrote this message on Tue, Jul 21, 2020 at 23:05 -0700: > Peter Libassi wrote this message on Wed, Jul 22, 2020 at 06:54 +0200: > > Is this related to > > > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234985 <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234985>; and https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=238326 <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=238326>; > > Definitely not 234985.. I'm using ue interfaces, and so they don't > get destroyed while the jail is going away... > > I don't think it's 238326 either. This is 100% reliable and it's in > the IP multicast code.. It looks like in_multi isn't holding an > interface or address lock waiting for things to free up... Did a little more poking, and it looks like the vnet is free'd before the ifnet is free'd causing this problem: (kgdb) print inm->inm_ifp[0].if_refcount $5 = 1 (kgdb) print inm->inm_ifp[0].if_vnet[0] $6 = {vnet_le = {le_next = 0xdeadc0dedeadc0de, le_prev = 0xdeadc0dedeadc0de}, vnet_magic_n = 3735929054, vnet_ifcnt = 3735929054, vnet_sockcnt = 3735929054, vnet_state = 3735929054, vnet_data_mem = 0xdeadc0dedeadc0de, vnet_data_base = 16045693110842147038, vnet_shutdown = 222} So the multicast code is fine, it holds and releases a reference to ifnet.. The issue is that the reference to the ifnet doesn't involve a reference to the vnet/prison. I have noticed that a number of times after a jail destroy that one of my interfaces doesn't make it back to the main OS.. it's just gone.. I can "make" it reappear by reseting the hardware, but that does imply that an ifnet is hanging out in limbo... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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