============================================ WARNING: possible recursive locking detected 6.1.129-syzkaller #0 Not tainted -------------------------------------------- syz-executor/4302 is trying to acquire lock: ffff0000f25e0218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000f25e0218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3894 [inline] ffff0000f25e0218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1b38/0x34d4 net/core/dev.c:4269 but task is already holding lock: ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3851 [inline] ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d4 net/core/dev.c:4269 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 syz-executor/4302: #0: ffff800015cc77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #1: ffff800015cc77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #2: ffff800015cc77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #3: ffff800015cc7840 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #4: ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #4: ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #4: ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3851 [inline] #4: ffff0000f5622258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d4 net/core/dev.c:4269 #5: ffff800015cc77e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #6: ffff800015cc7840 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 stack backtrace: CPU: 1 PID: 4302 Comm: syz-executor Not tainted 6.1.129-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 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:3894 [inline] __dev_queue_xmit+0x1b38/0x34d4 net/core/dev.c:4269 dev_queue_xmit include/linux/netdevice.h:3049 [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:444 [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:4894 [inline] netdev_start_xmit include/linux/netdevice.h:4908 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3864 [inline] __dev_queue_xmit+0x1438/0x34d4 net/core/dev.c:4269 dev_queue_xmit include/linux/netdevice.h:3049 [inline] br_dev_queue_push_xmit+0x584/0x730 net/bridge/br_forward.c:53 br_nf_dev_queue_xmit+0x3f4/0x1894 NF_HOOK+0x6a0/0x750 include/linux/netfilter.h:302 br_nf_post_routing+0x83c/0xc18 net/bridge/br_netfilter_hooks.c:978 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline] nf_hook_slow+0xc8/0x1f4 net/netfilter/core.c:614 nf_hook include/linux/netfilter.h:257 [inline] NF_HOOK+0x258/0x408 include/linux/netfilter.h:300 br_forward_finish+0xd0/0x118 net/bridge/br_forward.c:66 br_nf_forward_finish+0x8c8/0xcc8 net/bridge/br_netfilter_hooks.c:685 NF_HOOK+0x6a0/0x750 include/linux/netfilter.h:302 br_nf_forward_ip+0xa10/0xe78 net/bridge/br_netfilter_hooks.c:755 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline] nf_hook_slow+0xc8/0x1f4 net/netfilter/core.c:614 nf_hook include/linux/netfilter.h:257 [inline] NF_HOOK+0x258/0x408 include/linux/netfilter.h:300 __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_handle_frame_finish+0x10e4/0x1634 net/bridge/br_input.c:198 br_nf_hook_thresh+0x38c/0x480 br_nf_pre_routing_finish_ipv6+0x88c/0xbb0 NF_HOOK include/linux/netfilter.h:302 [inline] br_nf_pre_routing_ipv6+0x2ac/0x62c net/bridge/br_netfilter_ipv6.c:243 br_nf_pre_routing+0x5a0/0x11cc net/bridge/br_netfilter_hooks.c:528 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline] nf_hook_bridge_pre net/bridge/br_input.c:260 [inline] br_handle_frame+0x804/0x104c net/bridge/br_input.c:406 __netif_receive_skb_core+0xef0/0x378c net/core/dev.c:5432 __netif_receive_skb_one_core net/core/dev.c:5536 [inline] __netif_receive_skb+0x114/0x400 net/core/dev.c:5652 process_backlog+0x410/0x784 net/core/dev.c:5980 __napi_poll+0xb4/0x3f0 net/core/dev.c:6547 napi_poll net/core/dev.c:6614 [inline] net_rx_action+0x5cc/0xd3c net/core/dev.c:6728 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 do_softirq+0xf8/0x1ac kernel/softirq.c:479 __local_bh_enable_ip+0x298/0x470 kernel/softirq.c:403 local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33 put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:274 [inline] fpsimd_restore_current_state+0x110/0x26c arch/arm64/kernel/fpsimd.c:1731 do_notify_resume+0x1890/0x2cb8 arch/arm64/kernel/signal.c:1135 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x9c/0x168 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585