============================================ WARNING: possible recursive locking detected 6.8.0-rc7-syzkaller-g707081b61156 #0 Not tainted -------------------------------------------- syz-executor.0/6625 is trying to acquire lock: ffff0000c8e55cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000c8e55cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4443 [inline] ffff0000c8e55cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1160/0x329c net/core/dev.c:4347 but task is already holding lock: ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4443 [inline] ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x170/0x57c 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 6 locks held by syz-executor.0/6625: #0: ffff80008ee74ac0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:297 #1: ffff80008ee74b20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:297 #2: ffff0000c73c3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #2: ffff0000c73c3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #2: ffff0000c73c3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3763 [inline] #2: ffff0000c73c3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0xf14/0x329c net/core/dev.c:4317 #3: ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4443 [inline] #3: ffff0000d851d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x170/0x57c net/sched/sch_generic.c:340 #4: ffff80008ee74ac0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:297 #5: ffff80008ee74b20 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:297 stack backtrace: CPU: 1 PID: 6625 Comm: syz-executor.0 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 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:4443 [inline] __dev_queue_xmit+0x1160/0x329c net/core/dev.c:4347 dev_queue_xmit include/linux/netdevice.h:3171 [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/0x2630 net/ipv4/ip_tunnel.c:845 __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:4980 [inline] netdev_start_xmit include/linux/netdevice.h:4994 [inline] xmit_one net/core/dev.c:3547 [inline] dev_hard_start_xmit+0x240/0x8ac net/core/dev.c:3563 sch_direct_xmit+0x244/0x57c net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3776 [inline] __dev_queue_xmit+0x13c0/0x329c net/core/dev.c:4317 dev_queue_xmit include/linux/netdevice.h:3171 [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 net/ipv4/ip_output.c:129 [inline] ip_send_skb+0x134/0x2f8 net/ipv4/ip_output.c:1492 udp_send_skb+0x800/0x13ac net/ipv4/udp.c:963 udp_sendmsg+0x17cc/0x2584 net/ipv4/udp.c:1250 udpv6_sendmsg+0x99c/0x2860 net/ipv6/udp.c:1390 inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:660 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x56c/0x840 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmmsg+0x318/0x7d8 net/socket.c:2724 __do_sys_sendmmsg net/socket.c:2753 [inline] __se_sys_sendmmsg net/socket.c:2750 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2750 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598