============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.78/5076 is trying to acquire lock: ffff0000d667d398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] ffff0000d667d398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline] ffff0000d667d398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x138/0x3c8 net/sched/sch_generic.c:343 but task is already holding lock: ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline] ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x138/0x3c8 net/sched/sch_generic.c:343 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 13 locks held by syz.0.78/5076: #0: ffff800014461360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:312 #1: ffff8000144613c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #2: ffff8000144613c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #3: ffff0000d8818258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline] #3: ffff0000d8818258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a0 include/net/sch_generic.h:173 #4: ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #4: ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4446 [inline] #4: ffff0000d2469898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x138/0x3c8 net/sched/sch_generic.c:343 #5: ffff0000ec9580a0 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline] #5: ffff0000ec9580a0 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock+0xf0/0x140 net/ipv6/icmp.c:118 #6: ffff800014461360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:312 #7: ffff800014461360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #8: ffff8000144613c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #9: ffff800014461360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:312 #10: ffff8000144613c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #11: ffff8000144613c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:312 #12: ffff0000db8cd258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline] #12: ffff0000db8cd258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a0 include/net/sch_generic.h:173 stack backtrace: CPU: 1 PID: 5076 Comm: syz.0.78 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 __lock_acquire+0x15bc/0x67ec kernel/locking/lockdep.c:-1 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:364 [inline] __netif_tx_lock include/linux/netdevice.h:4446 [inline] sch_direct_xmit+0x138/0x3c8 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:3897 [inline] __dev_queue_xmit+0x1410/0x2844 net/core/dev.c:4266 dev_queue_xmit+0x24/0x34 net/core/dev.c:4334 neigh_resolve_output+0x530/0x5e0 net/core/neighbour.c:1504 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x12cc/0x1a10 net/ipv6/ip6_output.c:130 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:211 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x500 net/ipv6/ip6_output.c:234 dst_output include/net/dst.h:452 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xc00/0x163c net/ipv6/ndisc.c:513 ndisc_send_ns+0x528/0x6f0 net/ipv6/ndisc.c:655 ndisc_solicit+0x2b4/0x410 net/ipv6/ndisc.c:-1 neigh_probe+0xc4/0x130 net/core/neighbour.c:1017 __neigh_event_send+0xbe8/0x1198 net/core/neighbour.c:1178 neigh_event_send include/net/neighbour.h:438 [inline] neigh_resolve_output+0x180/0x5e0 net/core/neighbour.c:1488 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x12cc/0x1a10 net/ipv6/ip6_output.c:130 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:211 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x500 net/ipv6/ip6_output.c:234 dst_output include/net/dst.h:452 [inline] ip6_local_out+0x120/0x15c net/ipv6/output_core.c:161 ip6_send_skb+0x1a8/0x4f4 net/ipv6/ip6_output.c:1952 ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:1973 icmpv6_push_pending_frames+0x238/0x394 net/ipv6/icmp.c:311 icmp6_send+0xf68/0x14e0 net/ipv6/icmp.c:630 __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:2788 dst_link_failure+0x11c/0x160 include/net/dst.h:422 ip_tunnel_xmit+0x175c/0x1f44 net/ipv4/ip_tunnel.c:830 __gre_xmit net/ipv4/ip_gre.c:474 [inline] erspan_xmit+0x894/0x1490 net/ipv4/ip_gre.c:723 __netdev_start_xmit include/linux/netdevice.h:5036 [inline] netdev_start_xmit include/linux/netdevice.h:5050 [inline] xmit_one net/core/dev.c:3662 [inline] dev_hard_start_xmit+0x298/0x864 net/core/dev.c:3678 sch_direct_xmit+0x2b8/0x3c8 net/sched/sch_generic.c:345 __dev_xmit_skb net/core/dev.c:3897 [inline] __dev_queue_xmit+0x1410/0x2844 net/core/dev.c:4266 dev_queue_xmit+0x24/0x34 net/core/dev.c:4334 neigh_resolve_output+0x530/0x5e0 net/core/neighbour.c:1504 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x12cc/0x1a10 net/ipv6/ip6_output.c:130 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:211 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x274/0x500 net/ipv6/ip6_output.c:234 dst_output include/net/dst.h:452 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] rawv6_send_hdrinc+0xdec/0x1890 net/ipv6/raw.c:691 rawv6_sendmsg+0xdbc/0x12f4 net/ipv6/raw.c:949 inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] sock_write_iter+0x250/0x340 net/socket.c:1089 call_write_iter include/linux/fs.h:2173 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x590/0xa60 fs/read_write.c:594 ksys_write+0x12c/0x224 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584