============================================ WARNING: possible recursive locking detected 6.1.131-syzkaller #0 Not tainted -------------------------------------------- kworker/u4:9/4422 is trying to acquire lock: ffff0000dbfcb218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000dbfcb218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline] ffff0000dbfcb218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1b38/0x34d4 net/core/dev.c:4300 but task is already holding lock: ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline] ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d4 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/u4:9/4422: #0: ffff0000d691e938 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work+0x6bc/0x1484 kernel/workqueue.c:2265 #1: ffff800021587c20 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x1484 kernel/workqueue.c:2267 #2: ffff800008007c60 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #2: ffff800008007c60 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd0/0xa1c kernel/time/timer.c:1494 #3: ffff800015cd77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #4: ffff800015cd77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #5: ffff800015cd7840 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #6: ffff800015cd77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #7: ffff800015cd7840 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #8: ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #8: ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #8: ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline] #8: ffff0000dcaa3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d4 net/core/dev.c:4300 #9: ffff800015cd77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #10: ffff800015cd7840 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 stack backtrace: CPU: 0 PID: 4422 Comm: kworker/u4:9 Not tainted 6.1.131-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: bat_events batadv_nc_worker Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 __lock_acquire+0x6310/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc 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+0x1b38/0x34d4 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+0xc9c/0x11f0 net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x268 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x330/0x49c net/ipv4/ip_output.c:430 dst_output include/net/dst.h:453 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126 iptunnel_xmit+0x410/0x8f0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x18bc/0x1f9c net/ipv4/ip_tunnel.c:858 __gre_xmit net/ipv4/ip_gre.c:474 [inline] gre_tap_xmit+0x414/0x600 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+0x25c/0x9a4 net/core/dev.c:3674 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3895 [inline] __dev_queue_xmit+0x1438/0x34d4 net/core/dev.c:4300 dev_queue_xmit include/linux/netdevice.h:3051 [inline] br_dev_queue_push_xmit+0x584/0x730 net/bridge/br_forward.c:53 NF_HOOK+0x35c/0x408 include/linux/netfilter.h:302 br_forward_finish+0xd0/0x118 net/bridge/br_forward.c:66 NF_HOOK+0x35c/0x408 include/linux/netfilter.h:302 __br_forward+0x2f4/0x464 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xc8/0x178 net/bridge/br_forward.c:189 br_flood+0x28c/0x3f8 net/bridge/br_forward.c:231 br_dev_xmit+0xdec/0x1520 __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+0x25c/0x9a4 net/core/dev.c:3674 __dev_queue_xmit+0x161c/0x34d4 net/core/dev.c:4334 dev_queue_xmit include/linux/netdevice.h:3051 [inline] neigh_resolve_output+0x558/0x658 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdf8/0x1bc0 net/ipv6/ip6_output.c:138 __ip6_finish_output net/ipv6/ip6_output.c:205 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:216 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x594 net/ipv6/ip6_output.c:237 dst_output include/net/dst.h:453 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xcb0/0x18a0 net/ipv6/ndisc.c:513 ndisc_send_rs+0x3b8/0x4e0 net/ipv6/ndisc.c:723 addrconf_rs_timer+0x300/0x58c net/ipv6/addrconf.c:3982 call_timer_fn+0x1c0/0xa1c kernel/time/timer.c:1504 expire_timers kernel/time/timer.c:1549 [inline] __run_timers+0x554/0x718 kernel/time/timer.c:1820 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1833 handle_softirqs+0x318/0xd58 kernel/softirq.c:578 __do_softirq+0x14/0x20 kernel/softirq.c:612 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:893 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85 invoke_softirq kernel/softirq.c:459 [inline] __irq_exit_rcu+0x264/0x4d4 kernel/softirq.c:661 irq_exit_rcu+0x14/0x84 kernel/softirq.c:673 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline] el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581 arch_local_irq_enable arch/arm64/include/asm/irqflags.h:35 [inline] __local_bh_enable_ip+0x238/0x470 kernel/softirq.c:408 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x48/0x58 kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_nc_purge_paths+0x2f4/0x378 net/batman-adv/network-coding.c:471 batadv_nc_worker+0x2e4/0x580 net/batman-adv/network-coding.c:720 process_one_work+0x804/0x1484 kernel/workqueue.c:2292 worker_thread+0x8e4/0xfec kernel/workqueue.c:2439 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864 bridge0: received packet on gretap1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)