WARNING: locking bug in udpv6_pre_connect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    8f779443 net: phy: realtek: fix double page ops in generic..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=13f16ee8a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4005028a9d5ddac8
dashboard link: https://syzkaller.appspot.com/bug?extid=65f10c5aadc049eb5ef5
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+65f10c5aadc049eb5ef5@xxxxxxxxxxxxxxxxxxxxxxxxx

WARNING: CPU: 0 PID: 2749 at kernel/locking/lockdep.c:734  
arch_local_save_flags arch/x86/include/asm/paravirt.h:762 [inline]
WARNING: CPU: 0 PID: 2749 at kernel/locking/lockdep.c:734  
arch_local_save_flags arch/x86/include/asm/paravirt.h:760 [inline]
WARNING: CPU: 0 PID: 2749 at kernel/locking/lockdep.c:734  
look_up_lock_class kernel/locking/lockdep.c:725 [inline]
WARNING: CPU: 0 PID: 2749 at kernel/locking/lockdep.c:734  
register_lock_class+0xe10/0x1860 kernel/locking/lockdep.c:1078
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 2749 Comm: syz-executor.2 Not tainted 5.1.0+ #8
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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2cb/0x65c kernel/panic.c:214
 __warn.cold+0x20/0x45 kernel/panic.c:566
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:972
RIP: 0010:look_up_lock_class kernel/locking/lockdep.c:734 [inline]
RIP: 0010:register_lock_class+0xe10/0x1860 kernel/locking/lockdep.c:1078
Code: 00 48 89 da 4d 8b 76 c0 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80  
3c 02 00 0f 85 23 07 00 00 4c 89 33 e9 e3 f4 ff ff 0f 0b <0f> 0b e9 ea f3  
ff ff 44 89 e0 4c 8b 95 50 ff ff ff 83 c0 01 4c 8b
RSP: 0018:ffff8880475b79e8 EFLAGS: 00010083
RAX: dffffc0000000000 RBX: ffff888045e2f0a0 RCX: 0000000000000000
RDX: 1ffff11008bc5e17 RSI: 0000000000000000 RDI: ffff888045e2f0b8
RBP: ffff8880475b7ab0 R08: 1ffff11008eb6f45 R09: ffffffff8a455c80
R10: ffffffff8a0e2318 R11: 0000000000000000 R12: ffffffff8a11ed60
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87fe3860
 __lock_acquire+0x116/0x5490 kernel/locking/lockdep.c:3673
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4302
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:343 [inline]
 lock_sock_nested+0x41/0x120 net/core/sock.c:2917
 lock_sock include/net/sock.h:1525 [inline]
 udpv6_pre_connect net/ipv6/udp.c:1064 [inline]
 udpv6_pre_connect+0xc4/0x170 net/ipv6/udp.c:1046
 inet_dgram_connect+0x1cd/0x2e0 net/ipv4/af_inet.c:568
 __sys_connect+0x266/0x330 net/socket.c:1840
 __do_sys_connect net/socket.c:1851 [inline]
 __se_sys_connect net/socket.c:1848 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1848
 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458da9
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9ad544cc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458da9
RDX: 000000000000001c RSI: 0000000020000000 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9ad544d6d4
R13: 00000000004bf1fe R14: 00000000004d04b8 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.