TITLE: WARNING: locking bug in do_ipv6_setsockopt

[ 1056.836267] WARNING: CPU: 0 PID: 25919 at kernel/locking/lockdep.c:704 register_lock_class+0xce6/0x2650
[ 1056.845843] Kernel panic - not syncing: panic_on_warn set ...
[ 1056.845843] 
[ 1056.853235] CPU: 0 PID: 25919 Comm: syz-executor677 Not tainted 4.18.0-rc2+ #123
[ 1056.860758] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 1056.870278] Call Trace:
[ 1056.872932]  dump_stack+0x1c9/0x2b4
[ 1056.881749]  panic+0x238/0x4e7
[ 1056.901866]  __warn.cold.8+0x163/0x1ba
[ 1056.910409]  report_bug+0x252/0x2d0
[ 1056.914063]  do_error_trap+0x1fc/0x4d0
[ 1056.930922]  do_invalid_op+0x1b/0x20
[ 1056.934702]  invalid_op+0x14/0x20
[ 1056.938167] RIP: 0010:register_lock_class+0xce6/0x2650
[ 1056.943447] Code: f9 ff ff 4c 89 ff 44 89 85 68 fc ff ff 89 8d 70 fc ff ff e8 cc 99 5b 00 44 8b 85 68 fc ff ff 8b 8d 70 fc ff ff e9 6f f9 ff ff <0f> 0b e9 c8 f6 ff ff 48 8d 50 01 48 89 15 28 22 22 09 48 8d 14 80 
[ 1056.962595] RSP: 0018:ffff8801b0b7ee08 EFLAGS: 00010083
[ 1056.967960] RAX: 0000000000000004 RBX: ffffffff8a5c01b0 RCX: 0000000000000000
[ 1056.975244] RDX: ffffffff887db060 RSI: ffffffff886d1ee0 RDI: 1ffffffff154956c
[ 1056.982513] RBP: ffff8801b0b7f210 R08: 0000000000000000 R09: dffffc0000000000
[ 1056.989772] R10: 0000000000000000 R11: 0000000000000001 R12: 1ffff1003616fdd1
[ 1056.997042] R13: 0000000000000003 R14: 0000000000000000 R15: ffff8801b81f7920
[ 1057.078418]  __lock_acquire+0x1bd/0x5020
[ 1057.146655]  lock_acquire+0x1e4/0x540
[ 1057.172434]  _raw_spin_lock_bh+0x31/0x40
[ 1057.180708]  lock_sock_nested+0x46/0x120
[ 1057.184855]  do_ipv6_setsockopt.isra.9+0x5ba/0x4680
[ 1057.285171]  ipv6_setsockopt+0xbd/0x170
[ 1057.293306]  udpv6_setsockopt+0x62/0xa0
[ 1057.297280]  sock_common_setsockopt+0x9a/0xe0
[ 1057.301822]  __sys_setsockopt+0x1c5/0x3b0
[ 1057.318440]  __x64_sys_setsockopt+0xbe/0x150
[ 1057.327855]  do_syscall_64+0x1b9/0x820
[ 1057.351808]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 1057.356999] RIP: 0033:0x447c59
[ 1057.360810] Code: e8 bc bd 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00 
[ 1057.379923] RSP: 002b:00007f4e66aa9db8 EFLAGS: 00000297 ORIG_RAX: 0000000000000036
[ 1057.387641] RAX: ffffffffffffffda RBX: 00000000006e39fc RCX: 0000000000447c59
[ 1057.394895] RDX: 0000000000000037 RSI: 0000000000000029 RDI: 0000000000000006
[ 1057.402164] RBP: 00000000006e39f8 R08: 0000000000000010 R09: 0000000000000000
[ 1057.409431] R10: 0000000020000000 R11: 0000000000000297 R12: 0000000000000000
[ 1057.416689] R13: 00007ffcd170ce8f R14: 00007f4e66aaa9c0 R15: 0000000000000008
[ 1057.424756] Dumping ftrace buffer:
[ 1057.428278]    (ftrace buffer empty)
[ 1057.431980] Kernel Offset: disabled
[ 1057.435714] Rebooting in 86400 seconds..