============================================
WARNING: possible recursive locking detected
5.15.189-syzkaller #0 Not tainted
--------------------------------------------
kworker/u4:19/9783 is trying to acquire lock:
ffff0000d7168218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff0000d7168218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3909 [inline]
ffff0000d7168218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x18c8/0x2800 net/core/dev.c:4253

but task is already holding lock:
ffff0000e7384258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
ffff0000e7384258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a8 include/net/sch_generic.h:173

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

       CPU0
       ----
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

6 locks held by kworker/u4:19/9783:
 #0: ffff0000d36f5938 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
 #1: ffff800021b77c00 ((work_completion)(&(&forw_packet_aggr->delayed_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285
 #2: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #3: ffff0000e7384258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
 #3: ffff0000e7384258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a8 include/net/sch_generic.h:173
 #4: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #5: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311

stack backtrace:
CPU: 0 PID: 9783 Comm: kworker/u4:19 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 __lock_acquire+0x18a4/0x651c kernel/locking/lockdep.c:-1
 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:363 [inline]
 __dev_xmit_skb net/core/dev.c:3909 [inline]
 __dev_queue_xmit+0x18c8/0x2800 net/core/dev.c:4253
 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip_finish_output2+0xdac/0x1228 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:-1 [inline]
 ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x314/0x414 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:452 [inline]
 ip_local_out+0x120/0x15c net/ipv4/ip_output.c:126
 iptunnel_xmit+0x3f8/0x8dc net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x181c/0x1f30 net/ipv4/ip_tunnel.c:838
 __gre_xmit net/ipv4/ip_gre.c:474 [inline]
 gre_tap_xmit+0x3f8/0x5e4 net/ipv4/ip_gre.c:751
 __netdev_start_xmit include/linux/netdevice.h:5027 [inline]
 netdev_start_xmit include/linux/netdevice.h:5041 [inline]
 xmit_one net/core/dev.c:3649 [inline]
 dev_hard_start_xmit+0x2a8/0x87c net/core/dev.c:3665
 sch_direct_xmit+0x2a4/0x3bc net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3884 [inline]
 __dev_queue_xmit+0x13f4/0x2800 net/core/dev.c:4253
 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321
 batadv_send_skb_packet+0x284/0x4c0 net/batman-adv/send.c:108
 batadv_send_broadcast_skb+0x30/0x40 net/batman-adv/send.c:127
 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline]
 batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x670/0x858 net/batman-adv/bat_iv_ogm.c:1700
 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310
 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855