============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/u8:2/5716 is trying to acquire lock:
ffff8881175c2f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220

but task is already holding lock:
ffff8881102f8f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220

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

       CPU0
       ----
  lock(&hsr->seqnr_lock);
  lock(&hsr->seqnr_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

10 locks held by kworker/u8:2/5716:
 #0: ffff88802080d948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002dbfbc0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f537f48 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x112/0x14b0
 #3: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: ndisc_send_skb+0x20c/0x1440
 #4: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x701/0x16a0
 #5: ffffffff8e139f00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27b/0x3b50
 #6: ffff8881102f8f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220
 #7: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0x9e/0x2860
 #8: ffffffff8e139f00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27b/0x3b50
 #9: ffffffff8e139f00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27b/0x3b50

stack backtrace:
CPU: 1 UID: 0 PID: 5716 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_deadlock_bug+0x28b/0x2a0
 validate_chain+0x1a3f/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 _raw_spin_lock_bh+0x36/0x50
 hsr_dev_xmit+0x19a/0x220
 dev_hard_start_xmit+0x2d7/0x830
 __dev_queue_xmit+0x1b8d/0x3b50
 macvlan_start_xmit+0x46d/0x6e0
 dev_hard_start_xmit+0x2d7/0x830
 __dev_queue_xmit+0x1b8d/0x3b50
 hsr_forward_skb+0x158b/0x2860
 hsr_dev_xmit+0x1a5/0x220
 dev_hard_start_xmit+0x2d7/0x830
 __dev_queue_xmit+0x1b8d/0x3b50
 ip6_finish_output2+0x11fe/0x16a0
 ndisc_send_skb+0xb54/0x1440
 ndisc_send_ns+0xcb/0x150
 addrconf_dad_work+0xaae/0x14b0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
