syzbot

 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5570
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x904/0xdf0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:725
------------[ cut here ]------------
WARNING: CPU: 1 PID: 981 at lib/ref_tracker.c:38 spin_unlock_irqrestore include/linux/spinlock.h:404 [inline]
WARNING: CPU: 1 PID: 981 at lib/ref_tracker.c:38 ref_tracker_dir_exit.cold+0x137/0x1e3 lib/ref_tracker.c:37
Modules linked in:
CPU: 1 PID: 981 Comm: kworker/u4:5 Not tainted 5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:ref_tracker_dir_exit.cold+0x137/0x1e3 lib/ref_tracker.c:38
Code: 4c 89 ef e8 27 29 aa f8 4c 8b 3c 24 4c 39 fd 49 8b 07 0f 85 b5 00 00 00 e8 c2 b9 62 f8 48 8b 74 24 10 4c 89 e7 e8 25 15 36 00 <0f> 0b e9 91 40 e9 fa 4c 89 ff e8 f6 28 aa f8 e9 d4 fe ff ff e8 dc
RSP: 0018:ffffc90004897970 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffff88806ec6e600 R08: 0000000000000001 R09: ffffffff8ff9ba0f
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88806ec6e5b8
R13: ffff88806ec6e600 R14: ffff88806ec6e600 R15: ffff88806ec6e600
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f507edcd370 CR3: 000000000b88e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 free_netdev+0x32a/0x5b0 net/core/dev.c:10280
 netdev_run_todo+0x8a0/0xaa0 net/core/dev.c:9957
 default_device_exit_batch+0x2ff/0x3c0 net/core/dev.c:10938
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:171
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:595
 process_one_work+0x9b2/0x1660 kernel/workqueue.c:2298
 worker_thread+0x65d/0x1130 kernel/workqueue.c:2445
 kthread+0x405/0x4f0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>