Date:   Tue, 7 Dec 2021 20:52:02 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v3 net-next 00/23] net: add preliminary netdev refcount
 tracking

> I just sent the netns tracker series.
> 
> I will shortly send the remainder of netdev tracking patches.

Hi Eric

Thanks for sending the full set of patches.

I applied them on top of net-next. And i can still reproduce my
issue. This is without any changes of mine, just net-next plus your
two new patchsets.

It is not easy to reproduce. I needed to start/stop the GNS3
simulation around 8 times before i triggered it. I don't know how GNS3
does it tairdown. It could be there are active daemons running in the
name spaces as it removes the veth and tap devices? That might explain
why some of the leaks seem to be from TCP connection setup attempts?

Given i now have your full patchset, do you think these traces are
valid? Are they pointing at real leaks?

[ 1423.515246] unregister_netdevice: waiting for eth0 to become free. Usage count = 9
[ 1423.515747] leaked reference.
[ 1423.515755]  dst_alloc+0x7a/0x180
[ 1423.515765]  ip6_dst_alloc+0x27/0x90
[ 1423.515771]  ip6_pol_route+0x257/0x430
[ 1423.515777]  ip6_pol_route_output+0x19/0x20
[ 1423.515781]  fib6_rule_lookup+0x18b/0x270
[ 1423.515789]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.515793]  ip6_route_output_flags+0x32/0xa0
[ 1423.515797]  ip6_dst_lookup_tail.constprop.0+0x181/0x240
[ 1423.515803]  ip6_dst_lookup_flow+0x43/0xa0
[ 1423.515808]  inet6_csk_route_socket+0x166/0x200
[ 1423.515815]  inet6_csk_xmit+0x56/0x130
[ 1423.515818]  __tcp_transmit_skb+0x53b/0xc30
[ 1423.515825]  __tcp_send_ack.part.0+0xc6/0x1a0
[ 1423.515829]  tcp_send_ack+0x1c/0x20
[ 1423.515834]  __tcp_ack_snd_check+0x42/0x200
[ 1423.515838]  tcp_rcv_established+0x27a/0x6f0
[ 1423.515842] leaked reference.
[ 1423.515843]  dst_alloc+0x7a/0x180
[ 1423.515848]  ip6_dst_alloc+0x27/0x90
[ 1423.515851]  ip6_pol_route+0x257/0x430
[ 1423.515855]  ip6_pol_route_output+0x19/0x20
[ 1423.515860]  fib6_rule_lookup+0x18b/0x270
[ 1423.515865]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.515869]  ip6_route_output_flags+0x32/0xa0
[ 1423.515872]  seg6_output_core+0x28d/0x320
[ 1423.515878]  seg6_output+0x33/0x120
[ 1423.515884]  lwtunnel_output+0x72/0xc0
[ 1423.515890]  ip6_local_out+0x61/0x70
[ 1423.515894]  ip6_send_skb+0x23/0x70
[ 1423.515898]  udp_v6_send_skb+0x207/0x460
[ 1423.515905]  udpv6_sendmsg+0xb13/0xdb0
[ 1423.515908]  inet6_sendmsg+0x65/0x70
[ 1423.515916]  sock_sendmsg+0x48/0x70
[ 1423.515920] leaked reference.
[ 1423.515922]  dst_alloc+0x7a/0x180
[ 1423.515926]  ip6_dst_alloc+0x27/0x90
[ 1423.515929]  ip6_pol_route+0x257/0x430
[ 1423.515933]  ip6_pol_route_output+0x19/0x20
[ 1423.515938]  fib6_rule_lookup+0x18b/0x270
[ 1423.515943]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.515946]  ip6_route_output_flags+0x32/0xa0
[ 1423.515949]  seg6_output_core+0x28d/0x320
[ 1423.515955]  seg6_output+0x33/0x120
[ 1423.515961]  lwtunnel_output+0x72/0xc0
[ 1423.515965]  ip6_local_out+0x61/0x70
[ 1423.515968]  ip6_send_skb+0x23/0x70
[ 1423.515973]  udp_v6_send_skb+0x207/0x460
[ 1423.515979]  udpv6_sendmsg+0xb13/0xdb0
[ 1423.515982]  inet6_sendmsg+0x65/0x70
[ 1423.515985]  sock_sendmsg+0x48/0x70
[ 1423.515988] leaked reference.
[ 1423.515990]  dst_alloc+0x7a/0x180
[ 1423.515993]  ip6_dst_alloc+0x27/0x90
[ 1423.515997]  ip6_pol_route+0x257/0x430
[ 1423.516001]  ip6_pol_route_output+0x19/0x20
[ 1423.516005]  fib6_rule_lookup+0x18b/0x270
[ 1423.516010]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.516014]  ip6_route_output_flags+0x32/0xa0
[ 1423.516017]  seg6_output_core+0x28d/0x320
[ 1423.516022]  seg6_output+0x33/0x120
[ 1423.516028]  lwtunnel_output+0x72/0xc0
[ 1423.516032]  ip6_local_out+0x61/0x70
[ 1423.516036]  ip6_send_skb+0x23/0x70
[ 1423.516040]  udp_v6_send_skb+0x207/0x460
[ 1423.516046]  udpv6_sendmsg+0xb13/0xdb0
[ 1423.516049]  inet6_sendmsg+0x65/0x70
[ 1423.516052]  sock_sendmsg+0x48/0x70
[ 1423.516055] leaked reference.
[ 1423.516057]  dst_alloc+0x7a/0x180
[ 1423.516061]  ip6_dst_alloc+0x27/0x90
[ 1423.516064]  ip6_pol_route+0x257/0x430
[ 1423.516068]  ip6_pol_route_output+0x19/0x20
[ 1423.516072]  fib6_rule_lookup+0x18b/0x270
[ 1423.516078]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.516081]  ip6_route_output_flags+0x32/0xa0
[ 1423.516084]  ip6_dst_lookup_tail.constprop.0+0x181/0x240
[ 1423.516088]  ip6_dst_lookup_flow+0x43/0xa0
[ 1423.516092]  inet6_csk_route_socket+0x166/0x200
[ 1423.516099]  inet6_csk_xmit+0x56/0x130
[ 1423.516102]  __tcp_transmit_skb+0x53b/0xc30
[ 1423.516106]  tcp_write_xmit+0x3d4/0x13f0
[ 1423.516110]  __tcp_push_pending_frames+0x37/0x100
[ 1423.516114]  tcp_push+0xd2/0x100
[ 1423.516122]  tcp_sendmsg_locked+0x2a7/0xdb0
[ 1423.516128] leaked reference.
[ 1423.516130]  dst_alloc+0x7a/0x180
[ 1423.516134]  ip6_dst_alloc+0x27/0x90
[ 1423.516137]  ip6_pol_route+0x257/0x430
[ 1423.516141]  ip6_pol_route_output+0x19/0x20
[ 1423.516146]  fib6_rule_lookup+0x18b/0x270
[ 1423.516151]  ip6_route_output_flags_noref+0xaa/0x110
[ 1423.516154]  ip6_route_output_flags+0x32/0xa0
[ 1423.516157]  ip6_dst_lookup_tail.constprop.0+0xde/0x240
[ 1423.516161]  ip6_dst_lookup_flow+0x43/0xa0
[ 1423.516166]  tcp_v6_connect+0x2a7/0x670
[ 1423.516171]  __inet_stream_connect+0xd1/0x3b0
[ 1423.516175]  inet_stream_connect+0x3b/0x60
[ 1423.516178]  __sys_connect_file+0x5f/0x70
[ 1423.516182]  __sys_connect+0xa2/0xd0
[ 1423.516186]  __x64_sys_connect+0x18/0x20
[ 1423.516190]  do_syscall_64+0x3b/0xc0
[ 1423.516197] leaked reference.
[ 1423.516198]  fib6_nh_init+0x30d/0x9c0
[ 1423.516203]  rtm_new_nexthop+0x68a/0x13a0
[ 1423.516208]  rtnetlink_rcv_msg+0x14f/0x380
[ 1423.516216]  netlink_rcv_skb+0x55/0x100
[ 1423.516222]  rtnetlink_rcv+0x15/0x20
[ 1423.516228]  netlink_unicast+0x230/0x340
[ 1423.516232]  netlink_sendmsg+0x252/0x4b0
[ 1423.516236]  sock_sendmsg+0x65/0x70
[ 1423.516240]  ____sys_sendmsg+0x24e/0x290
[ 1423.516243]  ___sys_sendmsg+0x81/0xc0
[ 1423.516247]  __sys_sendmsg+0x62/0xb0
[ 1423.516252]  __x64_sys_sendmsg+0x1d/0x20
[ 1423.516256]  do_syscall_64+0x3b/0xc0
[ 1423.516260]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 1423.516266] leaked reference.
[ 1423.516267]  ipv6_add_dev+0x13e/0x4f0
[ 1423.516273]  addrconf_notify+0x2ca/0x950
[ 1423.516280]  raw_notifier_call_chain+0x49/0x60
[ 1423.516288]  call_netdevice_notifiers_info+0x50/0x90
[ 1423.516293]  __dev_change_net_namespace+0x30d/0x6c0
[ 1423.516299]  do_setlink+0xdc/0x10b0
[ 1423.516306]  __rtnl_newlink+0x608/0xa10
[ 1423.516312]  rtnl_newlink+0x49/0x70
[ 1423.516318]  rtnetlink_rcv_msg+0x14f/0x380
[ 1423.516323]  netlink_rcv_skb+0x55/0x100
[ 1423.516328]  rtnetlink_rcv+0x15/0x20
[ 1423.516333]  netlink_unicast+0x230/0x340
[ 1423.516337]  netlink_sendmsg+0x252/0x4b0
[ 1423.516345]  sock_sendmsg+0x65/0x70
[ 1423.516348]  ____sys_sendmsg+0x24e/0x290
[ 1423.516352]  ___sys_sendmsg+0x81/0xc0

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