------------[ cut here ]------------
WARNING: CPU: 0 PID: 18154 at kernel/locking/lockdep.c:896 look_up_lock_class kernel/locking/lockdep.c:895 [inline]
WARNING: CPU: 0 PID: 18154 at kernel/locking/lockdep.c:896 register_lock_class+0x276/0x1490 kernel/locking/lockdep.c:1244
Modules linked in:
CPU: 0 PID: 18154 Comm: syz-executor.5 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:look_up_lock_class kernel/locking/lockdep.c:895 [inline]
RIP: 0010:register_lock_class+0x276/0x1490 kernel/locking/lockdep.c:1244
Code: 30 43 80 3c 2e 00 44 8b 7c 24 0c 48 8b 5c 24 10 74 08 48 89 df e8 7a 9b 64 00 48 c7 c0 60 59 7a 8f 48 39 03 0f 84 13 0a 00 00 <0f> 0b e9 0c 0a 00 00 44 8b 7c 24 0c e9 fd 09 00 00 4d 89 e7 e8 e1
RSP: 0018:ffffc9000240f0c0 EFLAGS: 00010006
RAX: ffffffff8f7a5960 RBX: ffff8880156d74e0 RCX: 61c8864680b583eb
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000240f160
RBP: ffffc9000240f1f0 R08: dffffc0000000000 R09: 0000000000000000
R10: fffffbfff1c2cd1e R11: 0000000000000000 R12: ffffffff8fdd7200
R13: dffffc0000000000 R14: 1ffff11002adae9c R15: 0000000000000000
FS:  00007f47cbb0f700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005615a76574a8 CR3: 0000000025415000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __lock_acquire+0x186/0x6040 kernel/locking/lockdep.c:4781
 lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:354 [inline]
 l2tp_xmit_core net/l2tp/l2tp_core.c:1044 [inline]
 l2tp_xmit_skb+0x83f/0x16a0 net/l2tp/l2tp_core.c:1109
 pppol2tp_sendmsg+0x412/0x7b0 net/l2tp/l2tp_ppp.c:319
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0x5a2/0x900 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmmsg+0x500/0x790 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2516
 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f47cbb0f188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 00000000004665f9
RDX: 0400000000000085 RSI: 0000000020000280 RDI: 0000000000000004
RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007fff38433b0f R14: 00007f47cbb0f300 R15: 0000000000022000