============================================ WARNING: possible recursive locking detected 6.1.141-syzkaller #0 Not tainted -------------------------------------------- kworker/1:16/4448 is trying to acquire lock: ffff0000d5667218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000d5667218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline] ffff0000d5667218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1a24/0x309c net/core/dev.c:4300 but task is already holding lock: ffff0000d0351258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2} , at: spin_trylock include/linux/spinlock.h:361 [inline] , at: qdisc_run_begin include/net/sch_generic.h:195 [inline] , at: __dev_xmit_skb net/core/dev.c:3882 [inline] , at: __dev_queue_xmit+0xe58/0x309c 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 11 locks held by kworker/1:16/4448: #0: ffff0000d5dab938 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265 #1: ffff800020ef7c20 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267 #2: ffff0000c2e32538 (&idev->mc_lock){+.+.}-{3:3}, at: mld_ifc_work+0x38/0xa94 net/ipv6/mcast.c:2658 #3: ffff800015246d00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #4: ffff800015246d00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #5: ffff800015246d60 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #6: ffff800015246d00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #7: ffff800015246d60 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #8: ffff0000d0351258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #8: ffff0000d0351258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #8: ffff0000d0351258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline] #8: ffff0000d0351258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0xe58/0x309c net/core/dev.c:4300 #9: ffff800015246d00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #10: ffff800015246d60 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 stack backtrace: CPU: 1 PID: 4448 Comm: kworker/1:16 Not tainted 6.1.141-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: mld mld_ifc_work Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __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+0x18b4/0x6544 kernel/locking/lockdep.c:-1 lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c 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+0x1a24/0x309c 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+0xb9c/0x10a4 net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:-1 ip_finish_output+0x40/0x268 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:453 [inline] ip_local_out+0x120/0x15c net/ipv4/ip_output.c:126 iptunnel_xmit+0x3f8/0x8cc net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x149c/0x2044 net/ipv4/ip_tunnel.c:858 __gre_xmit net/ipv4/ip_gre.c:474 [inline] gre_tap_xmit+0x408/0x5f4 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+0x244/0x8e0 net/core/dev.c:3674 sch_direct_xmit+0x204/0x480 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3895 [inline] __dev_queue_xmit+0x1384/0x309c net/core/dev.c:4300 dev_queue_xmit include/linux/netdevice.h:3051 [inline] bond_dev_queue_xmit+0x98/0x138 drivers/net/bonding/bond_main.c:307 bond_do_alb_xmit+0x5dc/0x7cc drivers/net/bonding/bond_alb.c:1358 bond_tlb_xmit+0x38/0x48 drivers/net/bonding/bond_alb.c:1416 __bond_start_xmit drivers/net/bonding/bond_main.c:5503 [inline] bond_start_xmit+0x988/0x1888 drivers/net/bonding/bond_main.c:5525 __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+0x244/0x8e0 net/core/dev.c:3674 __dev_queue_xmit+0x155c/0x309c net/core/dev.c:4334 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] ip6_finish_output2+0xd2c/0x1844 net/ipv6/ip6_output.c:138 __ip6_finish_output net/ipv6/ip6_output.c:205 [inline] ip6_finish_output+0x594/0x930 net/ipv6/ip6_output.c:216 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x500 net/ipv6/ip6_output.c:237 dst_output include/net/dst.h:453 [inline] NF_HOOK+0x15c/0x430 include/linux/netfilter.h:302 mld_sendpack+0x8a4/0x113c net/ipv6/mcast.c:1826 mld_send_cr net/ipv6/mcast.c:2127 [inline] mld_ifc_work+0x76c/0xa94 net/ipv6/mcast.c:2659 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292 worker_thread+0x8c8/0xfbc kernel/workqueue.c:2439 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864