============================================
WARNING: possible recursive locking detected
5.8.0-rc2-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.5/5086 is trying to acquire lock:
ffff88805ad40280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_nested include/linux/netdevice.h:4243 [inline]
ffff88805ad40280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:915 [inline]
ffff88805ad40280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xf4/0x190 net/core/dev_addr_lists.c:909

but task is already holding lock:
ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:358 [inline]
ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4248 [inline]
ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:914 [inline]
ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xb0/0x190 net/core/dev_addr_lists.c:909

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&vlan_netdev_addr_lock_key/1);
  lock(&vlan_netdev_addr_lock_key/1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor.5/5086:
 #0: ffffffff8a798948 (vlan_ioctl_mutex){+.+.}-{3:3}, at: sock_ioctl+0x4b8/0x730 net/socket.c:1155
 #1: ffffffff8a7b08e8 (rtnl_mutex){+.+.}-{3:3}, at: vlan_ioctl_handler+0xb7/0xeed net/8021q/vlan.c:554
 #2: ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:358 [inline]
 #2: ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4248 [inline]
 #2: ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:914 [inline]
 #2: ffff888059e16280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xb0/0x190 net/core/dev_addr_lists.c:909

stack backtrace:
CPU: 0 PID: 5086 Comm: syz-executor.5 Not tainted 5.8.0-rc2-syzkaller #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+0x18f/0x20d lib/dump_stack.c:118
 print_deadlock_bug kernel/locking/lockdep.c:2391 [inline]
 check_deadlock kernel/locking/lockdep.c:2432 [inline]
 validate_chain kernel/locking/lockdep.c:3202 [inline]
 __lock_acquire.cold+0x178/0x3f8 kernel/locking/lockdep.c:4380
 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959
 _raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
 netif_addr_lock_nested include/linux/netdevice.h:4243 [inline]
 dev_mc_unsync net/core/dev_addr_lists.c:915 [inline]
 dev_mc_unsync+0xf4/0x190 net/core/dev_addr_lists.c:909
 vlan_dev_stop+0x51/0x350 net/8021q/vlan_dev.c:315
 __dev_close_many+0x1b3/0x2e0 net/core/dev.c:1605
 dev_close_many+0x238/0x650 net/core/dev.c:1630
 vlan_device_event+0x8ef/0x2010 net/8021q/vlan.c:450
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2033
 call_netdevice_notifiers_extack net/core/dev.c:2045 [inline]
 call_netdevice_notifiers net/core/dev.c:2059 [inline]
 dev_close_many+0x30b/0x650 net/core/dev.c:1634
 rollback_registered_many+0x3af/0xf60 net/core/dev.c:8953
 rollback_registered net/core/dev.c:9021 [inline]
 unregister_netdevice_queue+0x2dd/0x570 net/core/dev.c:10102
 unregister_vlan_dev+0x2c0/0x570 net/8021q/vlan.c:111
 vlan_ioctl_handler+0x311/0xeed net/8021q/vlan.c:629
 sock_ioctl+0x4d1/0x730 net/socket.c:1157
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007ff4e5029c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004f4060 RCX: 000000000045cb29
RDX: 0000000020000040 RSI: 0000000000008983 RDI: 0000000000000005
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000006a7 R14: 00000000004d5580 R15: 00007ff4e502a6d4