WARNING in print_bfs_bug

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    65921376 Merge branch 'net-fix-nested-device-bugs'
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=13ee0a97600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
dashboard link: https://syzkaller.appspot.com/bug?extid=62ebe501c1ce9a91f68c
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+62ebe501c1ce9a91f68c@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
lockdep bfs error:-1
WARNING: CPU: 0 PID: 27915 at kernel/locking/lockdep.c:1696  
print_bfs_bug+0x5c/0x80 kernel/locking/lockdep.c:1696
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 27915 Comm: syz-executor.1 Not tainted 5.4.0-rc3+ #0
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+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 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+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:print_bfs_bug+0x5c/0x80 kernel/locking/lockdep.c:1696
Code: 07 00 74 2d 48 c7 c7 00 5f aa 8a c6 07 00 0f 1f 40 00 85 db 75 05 5b  
41 5c 5d c3 44 89 e6 48 c7 c7 e0 17 ac 87 e8 cc e0 eb ff <0f> 0b 5b 41 5c  
5d c3 0f 0b 48 c7 c7 d8 1f f3 88 e8 bf fc 55 00 eb
RSP: 0018:ffff88801a307688 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 00000000000135ee RSI: ffffffff815cb646 RDI: ffffed1003460ec3
RBP: ffff88801a307698 R08: ffff88809b026340 R09: ffffed1015d04101
R10: ffffed1015d04100 R11: ffff8880ae820807 R12: 00000000ffffffff
R13: ffff88809b026bd8 R14: ffff88801a307710 R15: 00000000000003b0
 check_path+0x36/0x40 kernel/locking/lockdep.c:1772
 check_noncircular+0x16d/0x3e0 kernel/locking/lockdep.c:1797
 check_prev_add kernel/locking/lockdep.c:2476 [inline]
 check_prevs_add kernel/locking/lockdep.c:2581 [inline]
 validate_chain kernel/locking/lockdep.c:2971 [inline]
 __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
 __mutex_lock_common kernel/locking/mutex.c:956 [inline]
 __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72
 vlan_ioctl_handler+0xd2/0xf93 net/8021q/vlan.c:554
 sock_ioctl+0x518/0x790 net/socket.c:1147
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459f39
Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f81d8fbec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f39
RDX: 0000000020000000 RSI: 0800000000008982 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f81d8fbf6d4
R13: 00000000004c1521 R14: 00000000004d4dc0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


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