============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.3061/15733 is trying to acquire lock:
ffff88807e26ac98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff88807e26ac98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff88807e26ac98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343

but task is already holding lock:
ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343

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

10 locks held by syz.1.3061/15733:
 #0: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #1: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #2: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #3: ffff88807e065258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
 #3: ffff88807e065258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
 #3: ffff88807e065258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3884 [inline]
 #3: ffff88807e065258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1120/0x2f80 net/core/dev.c:4266
 #4: ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #4: ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline]
 #4: ffff88802616d098 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343
 #5: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #6: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #7: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #8: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #9: ffff88814cba3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
 #9: ffff88814cba3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
 #9: ffff88814cba3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3884 [inline]
 #9: ffff88814cba3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1120/0x2f80 net/core/dev.c:4266

stack backtrace:
CPU: 0 PID: 15733 Comm: syz.1.3061 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 __lock_acquire+0x1236/0x7d10 kernel/locking/lockdep.c:-1
 lock_acquire+0x19e/0x400 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]
 sch_direct_xmit+0x162/0x4b0 net/sched/sch_generic.c:343
 __dev_xmit_skb net/core/dev.c:3897 [inline]
 __dev_queue_xmit+0x179f/0x2f80 net/core/dev.c:4266
 NF_HOOK+0x2fe/0x380 include/linux/netfilter.h:302
 arp_xmit+0x142/0x230 net/ipv4/arp.c:643
 arp_solicit+0xba5/0xde0 net/ipv4/arp.c:391
 neigh_probe net/core/neighbour.c:1017 [inline]
 __neigh_event_send+0xede/0x1470 net/core/neighbour.c:1178
 neigh_event_send include/net/neighbour.h:438 [inline]
 neigh_resolve_output+0x1b3/0x6a0 net/core/neighbour.c:1488
 neigh_output include/net/neighbour.h:509 [inline]
 ip_finish_output2+0xcbf/0x10a0 net/ipv4/ip_output.c:228
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434
 iptunnel_xmit+0x4d6/0x8e0 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x1905/0x2280 net/ipv4/ip_tunnel.c:824
 __gre_xmit net/ipv4/ip_gre.c:474 [inline]
 gre_tap_xmit+0x4f9/0x6e0 net/ipv4/ip_gre.c:751
 __netdev_start_xmit include/linux/netdevice.h:5036 [inline]
 netdev_start_xmit include/linux/netdevice.h:5050 [inline]
 xmit_one net/core/dev.c:3662 [inline]
 dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
 sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
 __dev_xmit_skb net/core/dev.c:3897 [inline]
 __dev_queue_xmit+0x179f/0x2f80 net/core/dev.c:4266
 neigh_output include/net/neighbour.h:509 [inline]
 ip_finish_output2+0xcbf/0x10a0 net/ipv4/ip_output.c:228
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434
 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:1588
 udp_send_skb+0x94a/0x1330 net/ipv4/udp.c:991
 udp_sendmsg+0x1aed/0x2370 net/ipv4/udp.c:1279
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
 __sys_sendmmsg+0x2ba/0x500 net/socket.c:2585
 __do_sys_sendmmsg net/socket.c:2614 [inline]
 __se_sys_sendmmsg net/socket.c:2611 [inline]
 __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2611
 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: 0033:0x7f1fc4459819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1fc26b3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f1fc46d2fa0 RCX: 00007f1fc4459819
RDX: 0000000000000001 RSI: 0000200000003380 RDI: 0000000000000005
RBP: 00007f1fc44efc91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000004040880 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1fc46d3038 R14: 00007f1fc46d2fa0 R15: 00007fff8464c088
 </TASK>