============================================ WARNING: possible recursive locking detected 5.15.186-syzkaller #0 Not tainted -------------------------------------------- kworker/0:9/4161 is trying to acquire lock: ffff0000d629e218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff0000d629e218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3909 [inline] ffff0000d629e218 (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: ffff0000cb424258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] ffff0000cb424258 (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 11 locks held by kworker/0:9/4161: #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283 #1: ffff80001f877c00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285 #2: ffff800008007b80 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline] #2: ffff800008007b80 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd0/0x858 kernel/time/timer.c:1441 #3: ffff800014331360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #4: ffff8000143313c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #5: ffff8000143313c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #6: ffff800014331360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #7: ffff8000143313c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #8: ffff0000cb424258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #8: ffff0000cb424258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin+0x120/0x2a8 include/net/sch_generic.h:173 #9: ffff8000143313c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #10: ffff8000143313c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 stack backtrace: CPU: 0 PID: 4161 Comm: kworker/0:9 Not tainted 5.15.186-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: events pwq_unbound_release_workfn 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+0x1b0/0x448 net/ipv4/ip_output.c:-1 ip_finish_output+0x40/0x218 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 __bond_start_xmit drivers/net/bonding/bond_main.c:-1 [inline] bond_start_xmit+0xd7c/0x154c drivers/net/bonding/bond_main.c:5164 __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 __dev_queue_xmit+0x12d8/0x2800 net/core/dev.c:4288 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321 neigh_resolve_output+0x530/0x5e0 net/core/neighbour.c:1504 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x12d0/0x1a14 net/ipv6/ip6_output.c:130 __ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:201 ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:211 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x500 net/ipv6/ip6_output.c:234 dst_output include/net/dst.h:452 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xc10/0x1684 net/ipv6/ndisc.c:513 ndisc_send_rs+0x484/0x624 net/ipv6/ndisc.c:707 addrconf_rs_timer+0x2fc/0x590 net/ipv6/addrconf.c:3962 call_timer_fn+0x19c/0x858 kernel/time/timer.c:1451 expire_timers kernel/time/timer.c:1496 [inline] __run_timers+0x46c/0x6c4 kernel/time/timer.c:1767 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1780 handle_softirqs+0x344/0xbf0 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline] invoke_softirq kernel/softirq.c:457 [inline] __irq_exit_rcu+0x240/0x440 kernel/softirq.c:659 irq_exit+0x14/0x88 kernel/softirq.c:683 handle_domain_irq+0x14c/0x1fc kernel/irq/irqdesc.c:711 gic_handle_irq+0x78/0x1c8 drivers/irqchip/irq-gic-v3.c:765 call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:855 do_interrupt_handler+0x6c/0x88 arch/arm64/kernel/entry-common.c:267 el1_interrupt+0x30/0x58 arch/arm64/kernel/entry-common.c:454 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] lockdep_unregister_key+0x30c/0x38c kernel/locking/lockdep.c:6332 wq_unregister_lockdep kernel/workqueue.c:3518 [inline] pwq_unbound_release_workfn+0x200/0x254 kernel/workqueue.c:3756 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