============================================ WARNING: possible recursive locking detected 6.1.74-syzkaller #0 Not tainted -------------------------------------------- syz-executor.2/17137 is trying to acquire lock: ffff0000d94b8cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000d94b8cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] ffff0000d94b8cd8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1320/0x38d8 net/core/dev.c:4289 but task is already holding lock: ffff0000cdf0a4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000cdf0a4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] ffff0000cdf0a4d8 (_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 8 locks held by syz-executor.2/17137: #0: ffff800015a04ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 #1: ffff800015a04d40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 #2: ffff800015a04ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #3: ffff800015a04d40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 #4: ffff0000fa8d0258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:360 [inline] #4: ffff0000fa8d0258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #4: ffff0000fa8d0258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline] #4: ffff0000fa8d0258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x10b4/0x38d8 net/core/dev.c:4259 #5: ffff0000cdf0a4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #5: ffff0000cdf0a4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] #5: ffff0000cdf0a4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 #6: ffff800015a04ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #7: ffff800015a04d40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 stack backtrace: CPU: 0 PID: 17137 Comm: syz-executor.2 Not tainted 6.1.74-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 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:350 [inline] __netif_tx_lock include/linux/netdevice.h:4304 [inline] __dev_queue_xmit+0x1320/0x38d8 net/core/dev.c:4289 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0xc8c/0x1198 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+0x40c/0x8ec net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x19b4/0x28f4 net/ipv4/ip_tunnel.c:813 __gre_xmit net/ipv4/ip_gre.c:469 [inline] erspan_xmit+0x9c8/0x1498 net/ipv4/ip_gre.c:718 __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:3854 [inline] __dev_queue_xmit+0x1658/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0xc8c/0x1198 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+0x40c/0x8ec net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x19b4/0x28f4 net/ipv4/ip_tunnel.c:813 __gre_xmit net/ipv4/ip_gre.c:469 [inline] ipgre_xmit+0x68c/0xa18 net/ipv4/ip_gre.c:664 __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 __dev_queue_xmit+0x186c/0x38d8 net/core/dev.c:4293 dev_queue_xmit include/linux/netdevice.h:3021 [inline] __bpf_tx_skb+0x160/0x258 net/core/filter.c:2117 __bpf_redirect+0x4bc/0xcb8 ____bpf_clone_redirect net/core/filter.c:2445 [inline] bpf_clone_redirect+0x1cc/0x2e8 net/core/filter.c:2417 bpf_prog_208b094576c80b22+0x90/0xc8 bpf_dispatcher_nop_func include/linux/bpf.h:979 [inline] __bpf_prog_run include/linux/filter.h:600 [inline] bpf_prog_run include/linux/filter.h:607 [inline] bpf_test_run+0x370/0x870 net/bpf/test_run.c:402 bpf_prog_test_run_skb+0x8d8/0x1094 net/bpf/test_run.c:1180 bpf_prog_test_run+0x2dc/0x364 kernel/bpf/syscall.c:3633 __sys_bpf+0x390/0x654 kernel/bpf/syscall.c:4986 __do_sys_bpf kernel/bpf/syscall.c:5072 [inline] __se_sys_bpf kernel/bpf/syscall.c:5070 [inline] __arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:5070 __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:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 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