WARNING: locking bug in register_lock_class

[syzbot <syzbot+892f961d5cef6601aaf7@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    1904148a361a Merge tag 'powerpc-4.18-3' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13ea3924400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a63be0c83e84d370
dashboard link: https://syzkaller.appspot.com/bug?extid=892f961d5cef6601aaf7
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10b0a434400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1360b160400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+892f961d5cef6601aaf7@syzkaller.appspotmail.com

WARNING: CPU: 0 PID: 25919 at kernel/locking/lockdep.c:704  
arch_local_save_flags arch/x86/include/asm/paravirt.h:778 [inline]
WARNING: CPU: 0 PID: 25919 at kernel/locking/lockdep.c:704  
look_up_lock_class kernel/locking/lockdep.c:695 [inline]
WARNING: CPU: 0 PID: 25919 at kernel/locking/lockdep.c:704  
register_lock_class+0xce6/0x2650 kernel/locking/lockdep.c:754
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 25919 Comm: syz-executor677 Not tainted 4.18.0-rc2+ #123
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
  panic+0x238/0x4e7 kernel/panic.c:184
  __warn.cold.8+0x163/0x1ba kernel/panic.c:536
  report_bug+0x252/0x2d0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:178 [inline]
  do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:778 [inline]
RIP: 0010:look_up_lock_class kernel/locking/lockdep.c:695 [inline]
RIP: 0010:register_lock_class+0xce6/0x2650 kernel/locking/lockdep.c:754
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
RSP: 0018:ffff8801b0b7ee08 EFLAGS: 00010083
RAX: 0000000000000004 RBX: ffffffff8a5c01b0 RCX: 0000000000000000
RDX: ffffffff887db060 RSI: ffffffff886d1ee0 RDI: 1ffffffff154956c
RBP: ffff8801b0b7f210 R08: 0000000000000000 R09: dffffc0000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 1ffff1003616fdd1
R13: 0000000000000003 R14: 0000000000000000 R15: ffff8801b81f7920
  __lock_acquire+0x1bd/0x5020 kernel/locking/lockdep.c:3323
  lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
  _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168
  spin_lock_bh include/linux/spinlock.h:315 [inline]
  lock_sock_nested+0x46/0x120 net/core/sock.c:2834
  lock_sock include/net/sock.h:1474 [inline]
  do_ipv6_setsockopt.isra.9+0x5ba/0x4680 net/ipv6/ipv6_sockglue.c:167
  ipv6_setsockopt+0xbd/0x170 net/ipv6/ipv6_sockglue.c:922
  udpv6_setsockopt+0x62/0xa0 net/ipv6/udp.c:1472
  sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3040
  __sys_setsockopt+0x1c5/0x3b0 net/socket.c:1911
  __do_sys_setsockopt net/socket.c:1922 [inline]
  __se_sys_setsockopt net/socket.c:1919 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1919
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447c59
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
RSP: 002b:00007f4e66aa9db8 EFLAGS: 00000297 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006e39fc RCX: 0000000000447c59
RDX: 0000000000000037 RSI: 0000000000000029 RDI: 0000000000000006
RBP: 00000000006e39f8 R08: 0000000000000010 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000297 R12: 0000000000000000
R13: 00007ffcd170ce8f R14: 00007f4e66aaa9c0 R15: 0000000000000008
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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