============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.709/7219 is trying to acquire lock:
ffff888078cd8898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff888078cd8898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff888078cd8898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1438/0x2ed0 net/core/dev.c:4284

but task is already holding lock:
ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x156/0x4a0 net/sched/sch_generic.c:340

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

       CPU0
       ----
  lock(_xmit_ETHER#2);
  lock(_xmit_ETHER#2);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

6 locks held by syz.0.709/7219:
 #0: ffffffff8c11c7c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #1: ffffffff8c11c7c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #2: ffff888022bae258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
 #2: ffff888022bae258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
 #2: ffff888022bae258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
 #2: ffff888022bae258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253
 #3: ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #3: ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
 #3: ffff888078684c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x156/0x4a0 net/sched/sch_generic.c:340
 #4: ffffffff8c11c7c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #5: ffffffff8c11c7c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313

stack backtrace:
CPU: 1 PID: 7219 Comm: syz.0.709 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 __lock_acquire+0x1227/0x7c60 kernel/locking/lockdep.c:-1
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:364 [inline]
 __netif_tx_lock include/linux/netdevice.h:4446 [inline]
 __dev_queue_xmit+0x1438/0x2ed0 net/core/dev.c:4284
 neigh_output include/net/neighbour.h:509 [inline]
 ip_finish_output2+0xca1/0x1080 net/ipv4/ip_output.c:228
 iptunnel_xmit+0x525/0x960 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x1b6f/0x2240 net/ipv4/ip_tunnel.c:824
 __gre_xmit net/ipv4/ip_gre.c:474 [inline]
 erspan_xmit+0x9d5/0x15a0 net/ipv4/ip_gre.c:723
 __netdev_start_xmit include/linux/netdevice.h:5036 [inline]
 netdev_start_xmit include/linux/netdevice.h:5050 [inline]
 xmit_one net/core/dev.c:3649 [inline]
 dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665
 sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3884 [inline]
 __dev_queue_xmit+0x170e/0x2ed0 net/core/dev.c:4253
 neigh_output include/net/neighbour.h:509 [inline]
 ip_finish_output2+0xca1/0x1080 net/ipv4/ip_output.c:228
 dst_output include/net/dst.h:452 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 ip_send_skb+0x129/0x1c0 net/ipv4/ip_output.c:1581
 udp_send_skb+0x94a/0x1330 net/ipv4/udp.c:991
 udp_sendmsg+0x1aaa/0x2340 net/ipv4/udp.c:1279
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2446
 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2500
 __sys_sendmsg net/socket.c:2529 [inline]
 __do_sys_sendmsg net/socket.c:2538 [inline]
 __se_sys_sendmsg+0x190/0x250 net/socket.c:2536
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa1c9095749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa1c72db038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fa1c92ec090 RCX: 00007fa1c9095749
RDX: 0000000000000000 RSI: 0000200000000380 RDI: 0000000000000003
RBP: 00007fa1c9119f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa1c92ec128 R14: 00007fa1c92ec090 R15: 00007fff7e61b508
 </TASK>