============================================ WARNING: possible recursive locking detected 6.7.0-rc6-syzkaller-gaafe7ad77b91 #0 Not tainted -------------------------------------------- syz-fuzzer/6128 is trying to acquire lock: ffff0000db845cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000db845cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4403 [inline] ffff0000db845cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1128/0x31d8 net/core/dev.c:4342 but task is already holding lock: ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4403 [inline] ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 7 locks held by syz-fuzzer/6128: #0: ffff800080007c80 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #0: ffff800080007c80 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd0/0x8cc kernel/time/timer.c:1690 #1: ffff80008e6c48c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:300 #2: ffff80008e6c4920 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:300 #3: ffff0000d127b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #3: ffff0000d127b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #3: ffff0000d127b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3759 [inline] #3: ffff0000d127b258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0xedc/0x31d8 net/core/dev.c:4312 #4: ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #4: ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4403 [inline] #4: ffff0000d746f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 #5: ffff80008e6c48c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:300 #6: ffff80008e6c4920 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:300 stack backtrace: CPU: 0 PID: 6128 Comm: syz-fuzzer Not tainted 6.7.0-rc6-syzkaller-gaafe7ad77b91 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 dump_stack+0x1c/0x28 lib/dump_stack.c:113 print_deadlock_bug+0x4e4/0x660 kernel/locking/lockdep.c:3012 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3856 [inline] __lock_acquire+0x5fe4/0x763c kernel/locking/lockdep.c:5137 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __netif_tx_lock include/linux/netdevice.h:4403 [inline] __dev_queue_xmit+0x1128/0x31d8 net/core/dev.c:4342 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xdf8/0x1394 net/ipv4/ip_output.c:235 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x44/0x2e4 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x1a8/0x21c net/ipv4/ip_output.c:433 dst_output include/net/dst.h:451 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:129 iptunnel_xmit+0x428/0x940 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x16cc/0x2654 net/ipv4/ip_tunnel.c:831 __gre_xmit+0x104/0x198 net/ipv4/ip_gre.c:469 erspan_xmit+0x928/0x13a0 net/ipv4/ip_gre.c:720 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3545 [inline] dev_hard_start_xmit+0x240/0x8ac net/core/dev.c:3561 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3772 [inline] __dev_queue_xmit+0x1388/0x31d8 net/core/dev.c:4312 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xdf8/0x1394 net/ipv4/ip_output.c:235 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x44/0x2e4 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x1a8/0x21c net/ipv4/ip_output.c:433 dst_output include/net/dst.h:451 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:129 igmpv3_sendpack+0x234/0x3b4 net/ipv4/igmp.c:427 igmpv3_send_cr net/ipv4/igmp.c:723 [inline] igmp_ifc_timer_expire+0xa60/0xccc net/ipv4/igmp.c:813 call_timer_fn+0x19c/0x8cc kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x55c/0x734 kernel/time/timer.c:2022 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:2035 __do_softirq+0x2d8/0xce4 kernel/softirq.c:553 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:886 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:86 invoke_softirq kernel/softirq.c:434 [inline] __irq_exit_rcu+0x1d8/0x434 kernel/softirq.c:632 irq_exit_rcu+0x14/0x84 kernel/softirq.c:644 el0_interrupt+0x6c/0x234 arch/arm64/kernel/entry-common.c:761 __el0_irq_handler_common+0x18/0x24 arch/arm64/kernel/entry-common.c:768 el0t_64_irq_handler+0x10/0x1c arch/arm64/kernel/entry-common.c:773 el0t_64_irq+0x190/0x194 arch/arm64/kernel/entry.S:596