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[204.195.22.127]) by smtp.gmail.com with ESMTPSA id x27sm3508545pfj.74.2020.03.19.15.41.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Mar 2020 15:41:16 -0700 (PDT) Date: Thu, 19 Mar 2020 15:41:08 -0700 From: Stephen Hemminger To: Jarod Wilson Cc: Eric Dumazet , Jay Vosburgh , LKML , Moshe Levi , Marcelo Ricardo Leitner , Netdev Subject: Re: [PATCH net] ipv6: don't auto-add link-local address to lag ports Message-ID: <20200319154108.2de87e34@hermes.lan> In-Reply-To: References: <20200318140605.45273-1-jarod@redhat.com> <8a88d1c8-c6b1-ad85-7971-e6ae8c6fa0e4@gmail.com> <25629.1584564113@famine> <3dbabf42-90e6-4c82-0b84-d1b1a9e8fadf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 19 Mar 2020 15:29:51 -0400 Jarod Wilson wrote: > On Thu, Mar 19, 2020 at 1:06 PM Eric Dumazet wrote: > > > > On 3/19/20 9:42 AM, Jarod Wilson wrote: > > > > > Interesting. We'll keep digging over here, but that's definitely not > > > working for this particular use case with OVS for whatever reason. > > > > I did a quick test and confirmed that my bonding slaves do not have link-local addresses, > > without anything done to prevent them to appear. > > > > You might add a selftest, if you ever find what is the trigger :) > > Okay, have a basic reproducer, courtesy of Marcelo: > > # ip link add name bond0 type bond > # ip link set dev ens2f0np0 master bond0 > # ip link set dev ens2f1np2 master bond0 > # ip link set dev bond0 up > # ip a s > 1: lo: mtu 65536 qdisc noqueue state UNKNOWN > group default qlen 1000 > link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 > inet 127.0.0.1/8 scope host lo > valid_lft forever preferred_lft forever > inet6 ::1/128 scope host > valid_lft forever preferred_lft forever > 2: ens2f0np0: mtu 1500 qdisc > mq master bond0 state UP group default qlen 1000 > link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff > 5: ens2f1np2: mtu 1500 qdisc > mq master bond0 state DOWN group default qlen 1000 > link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff > 11: bond0: mtu 1500 qdisc > noqueue state UP group default qlen 1000 > link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff > inet6 fe80::20f:53ff:fe2f:ea40/64 scope link > valid_lft forever preferred_lft forever > > (above trimmed to relevant entries, obviously) > > # sysctl net.ipv6.conf.ens2f0np0.addr_gen_mode=0 > net.ipv6.conf.ens2f0np0.addr_gen_mode = 0 > # sysctl net.ipv6.conf.ens2f1np2.addr_gen_mode=0 > net.ipv6.conf.ens2f1np2.addr_gen_mode = 0 > > # ip a l ens2f0np0 > 2: ens2f0np0: mtu 1500 qdisc > mq master bond0 state UP group default qlen 1000 > link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff > inet6 fe80::20f:53ff:fe2f:ea40/64 scope link tentative > valid_lft forever preferred_lft forever > # ip a l ens2f1np2 > 5: ens2f1np2: mtu 1500 qdisc > mq master bond0 state DOWN group default qlen 1000 > link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff > inet6 fe80::20f:53ff:fe2f:ea40/64 scope link tentative > valid_lft forever preferred_lft forever > > Looks like addrconf_sysctl_addr_gen_mode() bypasses the original "is > this a slave interface?" check, and results in an address getting > added, while w/the proposed patch added, no address gets added. > > Looking back through git history again, I see a bunch of 'Fixes: > d35a00b8e33d ("net/ipv6: allow sysctl to change link-local address > generation mode")' patches, and I guess that's where this issue was > also introduced. > Yes the addrgen mode patches caused bad things to happen with hyper-v sub devices. Addrconf code is very tricky to get right. If you look back there have been a large number of changes where a patch looks good, gets reviewed, merged, and then breaks something and has to be reverted. Probably the original patch should just be reverted rather than trying to add more here.