syzbot

============================================
WARNING: possible recursive locking detected
6.1.148-syzkaller #0 Not tainted
--------------------------------------------
kworker/u4:25/8656 is trying to acquire lock:
ffff888055f90218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888055f90218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline]
ffff888055f90218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300

but task is already holding lock:
ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300

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

7 locks held by kworker/u4:25/8656:
 #0: ffff888077a4f138 ((wq_completion)bond1){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc900047ffd00 ((work_completion)(&(&bond->alb_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #2: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #2: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: bond_alb_monitor+0xee/0x17f0 drivers/net/bonding/bond_alb.c:1547
 #3: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #3: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
 #3: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
 #4: ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
 #4: ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
 #4: ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
 #4: ffff88801db63258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300
 #5: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #5: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #5: ffffffff8cb2ade0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x3e8/0x11b0 net/ipv4/ip_output.c:221
 #6: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #6: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
 #6: ffffffff8cb2ae40 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257

stack backtrace:
CPU: 0 PID: 8656 Comm: kworker/u4:25 Not tainted 6.1.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bond1 bond_alb_monitor
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 __dev_xmit_skb net/core/dev.c:3925 [inline]
 __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 neigh_hh_output include/net/neighbour.h:528 [inline]
 neigh_output include/net/neighbour.h:542 [inline]
 ip_finish_output2+0xbe8/0x11b0 net/ipv4/ip_output.c:228
 iptunnel_xmit+0x525/0x930 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x1c39/0x2360 net/ipv4/ip_tunnel.c:858
 __gre_xmit net/ipv4/ip_gre.c:474 [inline]
 gre_tap_xmit+0x50b/0x700 net/ipv4/ip_gre.c:751
 __netdev_start_xmit include/linux/netdevice.h:4896 [inline]
 netdev_start_xmit include/linux/netdevice.h:4910 [inline]
 xmit_one net/core/dev.c:3658 [inline]
 dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674
 sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3895 [inline]
 __dev_queue_xmit+0x18cd/0x3760 net/core/dev.c:4300
 alb_send_learning_packets+0x10a/0x2c0 drivers/net/bonding/bond_alb.c:1012
 bond_alb_monitor+0x3e1/0x17f0 drivers/net/bonding/bond_alb.c:1564
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready