IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready

===============================
[ INFO: suspicious RCU usage. ]
4.4.143-g7bbfac1 #13 Not tainted
-------------------------------
kernel/rcu/tree_plugin.h:685 Illegal synchronize_rcu() in RCU read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 1, debug_locks = 0
2 locks held by syz-executor0/4270:
 #0:  (rcu_read_lock_bh){......}, at: [<ffffffff8342b825>] ip6_finish_output2+0x1d5/0x1ca0 net/ipv6/ip6_output.c:71
 #1:  (&n->lock){++--..}, at: [<ffffffff82fa4aef>] __neigh_event_send+0x2f/0xc50 net/core/neighbour.c:969

stack backtrace:
CPU: 1 PID: 4270 Comm: syz-executor0 Not tainted 4.4.143-g7bbfac1 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 042fb8fda8e4f785 ffff8800b9b0f000 ffffffff81e1002d
 ffff8801d4ac8000 0000000000000000 0000000000000001 ffffffff83a676c0
 ffff8800b79f2dd8 ffff8800b9b0f030 ffffffff8140e407 ffff8800b79f2c80
Call Trace:
 [<ffffffff81e1002d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e1002d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8140e407>] lockdep_rcu_suspicious.cold.47+0x110/0x141 kernel/locking/lockdep.c:4305
 [<ffffffff81281aa8>] synchronize_rcu+0x78/0xa0 kernel/rcu/tree_plugin.h:682
 [<ffffffff835a166a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1702
 [<ffffffff835a19cb>] l2tp_tunnel_closeall+0x1cb/0x350 net/l2tp/l2tp_core.c:1270
 [<ffffffff835a22a2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1230
 [<ffffffff82f3128c>] sk_destruct+0x4c/0x4c0 net/core/sock.c:1447
 [<ffffffff82f3174f>] __sk_free+0x4f/0x220 net/core/sock.c:1480
 [<ffffffff82f336d3>] sock_wfree+0x103/0x140 net/core/sock.c:1667
 [<ffffffff82f37353>] skb_release_head_state+0x103/0x210 net/core/skbuff.c:646
 [<ffffffff82f39235>] skb_release_all+0x15/0x60 net/core/skbuff.c:659
 [<ffffffff82f39295>] __kfree_skb+0x15/0x20 net/core/skbuff.c:675
 [<ffffffff82f39397>] kfree_skb+0xf7/0x3e0 net/core/skbuff.c:696
 [<ffffffff82fa5112>] __neigh_event_send+0x652/0xc50 net/core/neighbour.c:1016
 [<ffffffff82faaa2b>] neigh_event_send include/net/neighbour.h:431 [inline]
 [<ffffffff82faaa2b>] neigh_resolve_output+0x4eb/0x790 net/core/neighbour.c:1310
 [<ffffffff8342bf79>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff8342bf79>] ip6_finish_output2+0x929/0x1ca0 net/ipv6/ip6_output.c:113
 [<ffffffff834355b8>] ip6_finish_output+0x3b8/0x760 net/ipv6/ip6_output.c:131
 [<ffffffff83435b18>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff83435b18>] ip6_output+0x1b8/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff8355f0bb>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff8355f0bb>] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:169
 [<ffffffff83437b51>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1725
 [<ffffffff834939fa>] udp_v6_send_skb+0x5ba/0xe70 net/ipv6/udp.c:1066
 [<ffffffff8349939e>] udpv6_sendmsg+0x1f2e/0x24c0 net/ipv6/udp.c:1330
 [<ffffffff83303083>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f2019c>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f2019c>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f21961>] ___sys_sendmsg+0x441/0x880 net/socket.c:1962
 [<ffffffff82f23fe4>] __sys_sendmmsg+0x1d4/0x2e0 net/socket.c:2040
 [<ffffffff8300daa2>] C_SYSC_sendmmsg net/compat.c:728 [inline]
 [<ffffffff8300daa2>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:725
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838c66ea>] sysenter_flags_fixed+0xd/0x17
BUG: sleeping function called from invalid context at kernel/sched/completion.c:90
in_atomic(): 1, irqs_disabled(): 0, pid: 4270, name: syz-executor0
INFO: lockdep is turned off.
Preemption disabled at:[<ffffffff834355b8>] ip6_finish_output+0x3b8/0x760 net/ipv6/ip6_output.c:131

CPU: 1 PID: 4270 Comm: syz-executor0 Not tainted 4.4.143-g7bbfac1 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 042fb8fda8e4f785 ffff8800b9b0ed80 ffffffff81e1002d
 ffff8801d4ac8000 0000000000000000 ffff8801d4ac8000 000000000000005a
 ffff8801d4ac8000 ffff8800b9b0edb8 ffffffff8140c525 ffff8801d4ac8000
Call Trace:
 [<ffffffff81e1002d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e1002d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8140c525>] ___might_sleep.cold.116+0x1bd/0x1d3 kernel/sched/core.c:7988
 [<ffffffff811a47a0>] __might_sleep+0x90/0x1a0 kernel/sched/core.c:7948
 [<ffffffff838b9d39>] __wait_for_common kernel/sched/completion.c:90 [inline]
 [<ffffffff838b9d39>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff838b9d39>] wait_for_completion+0x89/0x2e0 kernel/sched/completion.c:122
 [<ffffffff812773a7>] __wait_rcu_gp+0x137/0x1b0 kernel/rcu/update.c:347
 [<ffffffff8127faa4>] synchronize_rcu.part.55+0x94/0xd0 kernel/rcu/tree_plugin.h:691
 [<ffffffff81281a67>] synchronize_rcu+0x37/0xa0 kernel/rcu/tree_plugin.h:692
 [<ffffffff835a166a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1702
 [<ffffffff835a19cb>] l2tp_tunnel_closeall+0x1cb/0x350 net/l2tp/l2tp_core.c:1270
 [<ffffffff835a22a2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1230
 [<ffffffff82f3128c>] sk_destruct+0x4c/0x4c0 net/core/sock.c:1447
 [<ffffffff82f3174f>] __sk_free+0x4f/0x220 net/core/sock.c:1480
 [<ffffffff82f336d3>] sock_wfree+0x103/0x140 net/core/sock.c:1667
 [<ffffffff82f37353>] skb_release_head_state+0x103/0x210 net/core/skbuff.c:646
 [<ffffffff82f39235>] skb_release_all+0x15/0x60 net/core/skbuff.c:659
 [<ffffffff82f39295>] __kfree_skb+0x15/0x20 net/core/skbuff.c:675
 [<ffffffff82f39397>] kfree_skb+0xf7/0x3e0 net/core/skbuff.c:696
 [<ffffffff82fa5112>] __neigh_event_send+0x652/0xc50 net/core/neighbour.c:1016
 [<ffffffff82faaa2b>] neigh_event_send include/net/neighbour.h:431 [inline]
 [<ffffffff82faaa2b>] neigh_resolve_output+0x4eb/0x790 net/core/neighbour.c:1310
 [<ffffffff8342bf79>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff8342bf79>] ip6_finish_output2+0x929/0x1ca0 net/ipv6/ip6_output.c:113
 [<ffffffff834355b8>] ip6_finish_output+0x3b8/0x760 net/ipv6/ip6_output.c:131
 [<ffffffff83435b18>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff83435b18>] ip6_output+0x1b8/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff8355f0bb>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff8355f0bb>] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:169
 [<ffffffff83437b51>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1725
 [<ffffffff834939fa>] udp_v6_send_skb+0x5ba/0xe70 net/ipv6/udp.c:1066
 [<ffffffff8349939e>] udpv6_sendmsg+0x1f2e/0x24c0 net/ipv6/udp.c:1330
 [<ffffffff83303083>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f2019c>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f2019c>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f21961>] ___sys_sendmsg+0x441/0x880 net/socket.c:1962
 [<ffffffff82f23fe4>] __sys_sendmmsg+0x1d4/0x2e0 net/socket.c:2040
 [<ffffffff8300daa2>] C_SYSC_sendmmsg net/compat.c:728 [inline]
 [<ffffffff8300daa2>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:725
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838c66ea>] sysenter_flags_fixed+0xd/0x17
BUG: scheduling while atomic: syz-executor0/4270/0x00000402
INFO: lockdep is turned off.
Modules linked in:
Preemption disabled at:[<ffffffff834355b8>] ip6_finish_output+0x3b8/0x760 net/ipv6/ip6_output.c:131

CPU: 1 PID: 4270 Comm: syz-executor0 Not tainted 4.4.143-g7bbfac1 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 042fb8fda8e4f785 ffff8800b9b0ebd8 ffffffff81e1002d
 ffff8801d4ac8000 0000000000000402 000000000001f4c0 0000000000000000
 0000000000000001 ffff8800b9b0ebf8 ffffffff8140c619 ffff8801db31f4c0
Call Trace:
 [<ffffffff81e1002d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e1002d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8140c619>] __schedule_bug.cold.117+0xde/0x100 kernel/sched/core.c:3138
 [<ffffffff838b5fff>] schedule_debug kernel/sched/core.c:3153 [inline]
 [<ffffffff838b5fff>] __schedule+0x11ff/0x1d70 kernel/sched/core.c:3265
 [<ffffffff838b6d6a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3355
 [<ffffffff838c2181>] schedule_timeout+0x481/0x8b0 kernel/time/timer.c:1515
 [<ffffffff838b9eae>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff838b9eae>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff838b9eae>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff838b9eae>] wait_for_completion+0x1fe/0x2e0 kernel/sched/completion.c:122
 [<ffffffff812773a7>] __wait_rcu_gp+0x137/0x1b0 kernel/rcu/update.c:347
 [<ffffffff8127faa4>] synchronize_rcu.part.55+0x94/0xd0 kernel/rcu/tree_plugin.h:691
 [<ffffffff81281a67>] synchronize_rcu+0x37/0xa0 kernel/rcu/tree_plugin.h:692
 [<ffffffff835a166a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1702
 [<ffffffff835a19cb>] l2tp_tunnel_closeall+0x1cb/0x350 net/l2tp/l2tp_core.c:1270
 [<ffffffff835a22a2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1230
 [<ffffffff82f3128c>] sk_destruct+0x4c/0x4c0 net/core/sock.c:1447
 [<ffffffff82f3174f>] __sk_free+0x4f/0x220 net/core/sock.c:1480
 [<ffffffff82f336d3>] sock_wfree+0x103/0x140 net/core/sock.c:1667
 [<ffffffff82f37353>] skb_release_head_state+0x103/0x210 net/core/skbuff.c:646
 [<ffffffff82f39235>] skb_release_all+0x15/0x60 net/core/skbuff.c:659
 [<ffffffff82f39295>] __kfree_skb+0x15/0x20 net/core/skbuff.c:675
 [<ffffffff82f39397>] kfree_skb+0xf7/0x3e0 net/core/skbuff.c:696
 [<ffffffff82fa5112>] __neigh_event_send+0x652/0xc50 net/core/neighbour.c:1016
 [<ffffffff82faaa2b>] neigh_event_send include/net/neighbour.h:431 [inline]
 [<ffffffff82faaa2b>] neigh_resolve_output+0x4eb/0x790 net/core/neighbour.c:1310
 [<ffffffff8342bf79>] dst_neigh_output include/net/dst.h:461 [inline]
 [<ffffffff8342bf79>] ip6_finish_output2+0x929/0x1ca0 net/ipv6/ip6_output.c:113
 [<ffffffff834355b8>] ip6_finish_output+0x3b8/0x760 net/ipv6/ip6_output.c:131
 [<ffffffff83435b18>] NF_HOOK_COND include/linux/netfilter.h:240 [inline]
 [<ffffffff83435b18>] ip6_output+0x1b8/0x520 net/ipv6/ip6_output.c:145
 [<ffffffff8355f0bb>] dst_output include/net/dst.h:498 [inline]
 [<ffffffff8355f0bb>] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:169
 [<ffffffff83437b51>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1725
 [<ffffffff834939fa>] udp_v6_send_skb+0x5ba/0xe70 net/ipv6/udp.c:1066
 [<ffffffff8349939e>] udpv6_sendmsg+0x1f2e/0x24c0 net/ipv6/udp.c:1330
 [<ffffffff83303083>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff82f2019c>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82f2019c>] sock_sendmsg+0xcc/0x110 net/socket.c:635
 [<ffffffff82f21961>] ___sys_sendmsg+0x441/0x880 net/socket.c:1962
 [<ffffffff82f23fe4>] __sys_sendmmsg+0x1d4/0x2e0 net/socket.c:2040
 [<ffffffff8300daa2>] C_SYSC_sendmmsg net/compat.c:728 [inline]
 [<ffffffff8300daa2>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:725
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838c66ea>] sysenter_flags_fixed+0xd/0x17