============================================ WARNING: possible recursive locking detected 6.1.114-syzkaller #0 Not tainted -------------------------------------------- syz.5.240/5401 is trying to acquire lock: ffff0000db7ee218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000db7ee218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3888 [inline] ffff0000db7ee218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1b38/0x34d0 net/core/dev.c:4263 but task is already holding lock: ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3845 [inline] ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d0 net/core/dev.c:4263 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 9 locks held by syz.5.240/5401: #0: ffff800015ba5a80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #1: ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #1: ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #1: ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3845 [inline] #1: ffff0000ed81d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0xf04/0x34d0 net/core/dev.c:4263 #2: ffff800015ba5a20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #3: ffff800015ba5a80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #4: ffff0000d64207f0 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #4: ffff0000d64207f0 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock+0xec/0x19c net/ipv6/icmp.c:108 #5: ffff800015ba5a20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #6: ffff800015ba5a20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #7: ffff800015ba5a20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #8: ffff800015ba5a80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 stack backtrace: CPU: 1 PID: 5401 Comm: syz.5.240 Not tainted 6.1.114-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 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:3888 [inline] __dev_queue_xmit+0x1b38/0x34d0 net/core/dev.c:4263 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_connected_output+0x344/0x3d4 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdb8/0x1b54 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:444 [inline] ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161 ip6_send_skb+0x19c/0x570 net/ipv6/ip6_output.c:2005 ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:2026 icmpv6_push_pending_frames+0x288/0x3f4 net/ipv6/icmp.c:311 icmp6_send+0x11ac/0x1b8c net/ipv6/icmp.c:632 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2793 dst_link_failure include/net/dst.h:423 [inline] ipip6_tunnel_xmit net/ipv6/sit.c:1039 [inline] sit_tunnel_xmit+0xa88/0x1ee8 net/ipv6/sit.c:1076 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [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 qdisc_restart net/sched/sch_generic.c:407 [inline] __qdisc_run+0x904/0x239c net/sched/sch_generic.c:415 __dev_xmit_skb net/core/dev.c:3921 [inline] __dev_queue_xmit+0xcac/0x34d0 net/core/dev.c:4263 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_connected_output+0x344/0x3d4 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdb8/0x1b54 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:444 [inline] ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161 ip6tunnel_xmit+0x174/0x460 include/net/ip6_tunnel.h:161 ip6_tnl_xmit+0x1f0c/0x2698 net/ipv6/ip6_tunnel.c:1280 __gre6_xmit+0x7c8/0xadc net/ipv6/ip6_gre.c:809 ip6gre_xmit_other net/ipv6/ip6_gre.c:912 [inline] ip6gre_tunnel_xmit+0x9e0/0x12fc net/ipv6/ip6_gre.c:940 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [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:3858 [inline] __dev_queue_xmit+0x1438/0x34d0 net/core/dev.c:4263 dev_queue_xmit+0x24/0x34 include/linux/netdevice.h:3021 packet_snd net/packet/af_packet.c:3142 [inline] packet_sendmsg+0x36f0/0x4cd8 net/packet/af_packet.c:3173 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] __sys_sendto+0x3b8/0x508 net/socket.c:2153 __do_sys_sendto net/socket.c:2165 [inline] __se_sys_sendto net/socket.c:2161 [inline] __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2161 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585