l2tp_core: tunl 4: fd 4 wrong protocol, got 1, expected 17
l2tp_core: tunl 4: fd 4 wrong protocol, got 1, expected 17
l2tp_core: tunl 4: fd 4 wrong protocol, got 1, expected 17
l2tp_core: tunl 4: fd 4 wrong protocol, got 1, expected 17
------------[ cut here ]------------
WARNING: CPU: 0 PID: 14811 at kernel/locking/lockdep.c:728 look_up_lock_class kernel/locking/lockdep.c:728 [inline]()
WARNING: CPU: 0 PID: 14811 at kernel/locking/lockdep.c:728 register_lock_class kernel/locking/lockdep.c:750 [inline]()
WARNING: CPU: 0 PID: 14811 at kernel/locking/lockdep.c:728 __lock_acquire+0xdbf/0x1c70 kernel/locking/lockdep.c:3101()
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 14811 Comm: syz-executor.1 Not tainted 4.1.0 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffffffff82e342a8 ffff88012a623a38 ffffffff8263906b 0000000000000032
 ffffffff82e31403 ffff88012a623ab8 ffffffff82634efe ffff88012a623a58
 ffffffff00000008 ffff88012a623ac8 ffff88012a623a68 0000000000000000
Call Trace:
 [<ffffffff8263906b>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff8263906b>] dump_stack+0x4f/0x7b lib/dump_stack.c:50
 [<ffffffff82634efe>] panic+0xcd/0x211 kernel/panic.c:111
 [<ffffffff8116cdab>] warn_slowpath_common+0xbb/0xc0 kernel/panic.c:442
 [<ffffffff8116ce55>] warn_slowpath_null+0x15/0x20 kernel/panic.c:479
 [<ffffffff811c50bf>] look_up_lock_class kernel/locking/lockdep.c:728 [inline]
 [<ffffffff811c50bf>] register_lock_class kernel/locking/lockdep.c:750 [inline]
 [<ffffffff811c50bf>] __lock_acquire+0xdbf/0x1c70 kernel/locking/lockdep.c:3101
 [<ffffffff811c6a36>] lock_acquire+0xe6/0x310 kernel/locking/lockdep.c:3623
 [<ffffffff82647bda>] __raw_spin_lock_bh include/linux/spinlock_api_smp.h:137 [inline]
 [<ffffffff82647bda>] _raw_spin_lock_bh+0x3a/0x50 kernel/locking/spinlock.c:175
 [<ffffffff820d5822>] spin_lock_bh include/linux/spinlock.h:317 [inline]
 [<ffffffff820d5822>] lock_sock_nested+0x32/0xa0 net/core/sock.c:2369
 [<ffffffff822e78c2>] lock_sock include/net/sock.h:1486 [inline]
 [<ffffffff822e78c2>] do_ipv6_setsockopt.isra.7+0xb2/0x12b0 net/ipv6/ipv6_sockglue.c:165
 [<ffffffff822e8b0a>] ipv6_setsockopt+0x4a/0xb0 net/ipv6/ipv6_sockglue.c:885
 [<ffffffff822edca6>] udpv6_setsockopt+0x16/0x30 net/ipv6/udp.c:1422
 [<ffffffff820d4e8f>] sock_common_setsockopt+0xf/0x20 net/core/sock.c:2576
 [<ffffffff820d3b7c>] SYSC_setsockopt net/socket.c:1760 [inline]
 [<ffffffff820d3b7c>] SyS_setsockopt+0x6c/0xd0 net/socket.c:1739
 [<ffffffff826489f2>] system_call_fastpath+0x16/0x7a
Kernel Offset: disabled