============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.1.3999/21841 is trying to acquire lock: ffff888059086958 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888059086958 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] ffff888059086958 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 but task is already holding lock: ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&qdisc_xmit_lock_key#3); lock(&qdisc_xmit_lock_key#3); *** DEADLOCK *** May be due to missing lock nesting notation 14 locks held by syz.1.3999/21841: #0: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock_dont_migrate include/linux/rcupdate.h:995 [inline] #0: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: bpf_test_timer_enter+0xf7/0x260 net/bpf/test_run.c:39 #1: ffffc90000007d00 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbe/0x590 kernel/time/timer.c:1745 #2: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #2: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: ndisc_send_skb+0x1e4/0x1510 net/ipv6/ndisc.c:482 #3: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #3: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #3: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: ip6_output+0x126/0x550 net/ipv6/ip6_output.c:235 #4: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #4: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #4: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x289/0x31c0 net/core/dev.c:4744 #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0xc1/0x1940 drivers/net/bonding/bond_main.c:5486 #6: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #6: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #6: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x289/0x31c0 net/core/dev.c:4744 #7: ffff888058631228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #7: ffff888058631228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:202 [inline] #7: ffff888058631228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4156 [inline] #7: ffff888058631228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_queue_xmit+0xeb9/0x31c0 net/core/dev.c:4785 #8: ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] #8: ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] #8: ffff8880afd64158 (&qdisc_xmit_lock_key#3){+.-.}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 #9: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #9: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: ip_output+0x5b/0x450 net/ipv4/ip_output.c:433 #10: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #10: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #10: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x3d0/0x1000 net/ipv4/ip_output.c:230 #11: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #11: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #11: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: arp_xmit+0x23/0x270 net/ipv4/arp.c:662 #12: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #12: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #12: ffffffff8df41b00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x289/0x31c0 net/core/dev.c:4744 #13: ffff888030482228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #13: ffff888030482228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:202 [inline] #13: ffff888030482228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4156 [inline] #13: ffff888030482228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_queue_xmit+0xeb9/0x31c0 net/core/dev.c:4785 stack backtrace: CPU: 0 UID: 0 PID: 21841 Comm: syz.1.3999 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x2540/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __netif_tx_lock include/linux/netdevice.h:4710 [inline] sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 __dev_xmit_skb net/core/dev.c:4169 [inline] __dev_queue_xmit+0x1379/0x31c0 net/core/dev.c:4785 NF_HOOK+0x310/0x3a0 include/linux/netfilter.h:-1 arp_xmit+0x16c/0x270 net/ipv4/arp.c:664 arp_solicit+0xbbd/0xe10 net/ipv4/arp.c:392 neigh_probe net/core/neighbour.c:1097 [inline] __neigh_event_send+0xf3e/0x1520 net/core/neighbour.c:1270 neigh_event_send_probe include/net/neighbour.h:480 [inline] neigh_event_send include/net/neighbour.h:486 [inline] neigh_resolve_output+0x198/0x750 net/core/neighbour.c:1578 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xbb6/0x1000 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 iptunnel_xmit+0x5f8/0xa90 net/ipv4/ip_tunnel_core.c:84 ip_tunnel_xmit+0x1c41/0x2390 net/ipv4/ip_tunnel.c:845 __gre_xmit net/ipv4/ip_gre.c:490 [inline] gre_tap_xmit+0x590/0x7a0 net/ipv4/ip_gre.c:778 __netdev_start_xmit include/linux/netdevice.h:5273 [inline] netdev_start_xmit include/linux/netdevice.h:5282 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 sch_direct_xmit+0x241/0x4b0 net/sched/sch_generic.c:347 __dev_xmit_skb net/core/dev.c:4169 [inline] __dev_queue_xmit+0x1379/0x31c0 net/core/dev.c:4785 __bond_start_xmit include/linux/netdevice.h:-1 [inline] bond_start_xmit+0xd2c/0x1940 drivers/net/bonding/bond_main.c:5488 __netdev_start_xmit include/linux/netdevice.h:5273 [inline] netdev_start_xmit include/linux/netdevice.h:5282 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 __dev_queue_xmit+0x149d/0x31c0 net/core/dev.c:4819 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK include/linux/netfilter.h:318 [inline] ndisc_send_skb+0xbce/0x1510 net/ipv6/ndisc.c:512 addrconf_rs_timer+0x369/0x6a0 net/ipv6/addrconf.c:4037 call_timer_fn+0x16e/0x590 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2373 [inline] __run_timer_base+0x61a/0x860 kernel/time/timer.c:2385 run_timer_base kernel/time/timer.c:2394 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2404 handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] xdp_test_run_batch net/bpf/test_run.c:357 [inline] bpf_test_run_xdp_live+0x1880/0x1b20 net/bpf/test_run.c:379 bpf_prog_test_run_xdp+0x7c0/0x10e0 net/bpf/test_run.c:1388 bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4703 __sys_bpf+0x562/0x860 kernel/bpf/syscall.c:6182 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline] __se_sys_bpf kernel/bpf/syscall.c:6272 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6272 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f51f4f8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f51f5e89038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f51f51e5fa0 RCX: 00007f51f4f8f749 RDX: 0000000000000048 RSI: 0000200000000600 RDI: 000000000000000a RBP: 00007f51f5013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f51f51e6038 R14: 00007f51f51e5fa0 R15: 00007ffe239fcf28