============================================ WARNING: possible recursive locking detected 5.15.181-syzkaller #0 Not tainted -------------------------------------------- syz.0.149/5112 is trying to acquire lock: ffff0000eb733398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff0000eb733398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] ffff0000eb733398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x12c/0x3bc net/sched/sch_generic.c:340 but task is already holding lock: ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x12c/0x3bc 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 13 locks held by syz.0.149/5112: #0: ffff8000143211e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #1: ffff800014321240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #2: ffff800014321240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #3: ffff0000c8558258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #3: ffff0000c8558258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a8 include/net/sch_generic.h:173 #4: ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #4: ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] #4: ffff0000d0a48898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x12c/0x3bc net/sched/sch_generic.c:340 #5: ffff0000d73d9da0 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #5: ffff0000d73d9da0 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock+0xf0/0x140 net/ipv6/icmp.c:118 #6: ffff8000143211e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #7: ffff8000143211e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #8: ffff800014321240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #9: ffff8000143211e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #10: ffff800014321240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #11: ffff800014321240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #12: ffff0000d9dc3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #12: ffff0000d9dc3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x120/0x2a8 include/net/sch_generic.h:173 stack backtrace: CPU: 0 PID: 5112 Comm: syz.0.149 Not tainted 5.15.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Call trace: dump_backtrace+0x0/0x43c 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+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 __lock_acquire+0x18a4/0x651c kernel/locking/lockdep.c:-1 lock_acquire+0x1f4/0x620 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:363 [inline] __netif_tx_lock include/linux/netdevice.h:4437 [inline] sch_direct_xmit+0x12c/0x3bc net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x13f4/0x2800 net/core/dev.c:4253 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321 neigh_hh_output include/net/neighbour.h:493 [inline] neigh_output include/net/neighbour.h:507 [inline] ip6_finish_output2+0x129c/0x1a14 net/ipv6/ip6_output.c:130 __ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:201 ip6_finish_output+0x40/0x218 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+0xc10/0x1684 net/ipv6/ndisc.c:513 ndisc_send_ns+0x518/0x6f4 net/ipv6/ndisc.c:655 ndisc_solicit+0x2b0/0x408 net/ipv6/ndisc.c:-1 neigh_probe+0xc4/0x138 net/core/neighbour.c:1017 __neigh_event_send+0xc14/0x1200 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+0x12d0/0x1a14 net/ipv6/ip6_output.c:130 __ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:201 ip6_finish_output+0x40/0x218 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:1951 ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:1972 icmpv6_push_pending_frames+0x238/0x394 net/ipv6/icmp.c:311 icmp6_send+0xee4/0x144c 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+0x1444/0x1f30 net/ipv4/ip_tunnel.c:844 __gre_xmit net/ipv4/ip_gre.c:474 [inline] erspan_xmit+0x890/0x1490 net/ipv4/ip_gre.c:723 __netdev_start_xmit include/linux/netdevice.h:5027 [inline] netdev_start_xmit include/linux/netdevice.h:5041 [inline] xmit_one net/core/dev.c:3649 [inline] dev_hard_start_xmit+0x2a8/0x87c net/core/dev.c:3665 sch_direct_xmit+0x2a4/0x3bc net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x13f4/0x2800 net/core/dev.c:4253 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321 neigh_hh_output include/net/neighbour.h:493 [inline] neigh_output include/net/neighbour.h:507 [inline] ip6_finish_output2+0x129c/0x1a14 net/ipv6/ip6_output.c:130 __ip6_finish_output+0x570/0x6dc net/ipv6/ip6_output.c:201 ip6_finish_output+0x40/0x218 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+0xdb8/0x18cc net/ipv6/raw.c:691 rawv6_sendmsg+0xd9c/0x12e8 net/ipv6/raw.c:949 inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] sock_write_iter+0x23c/0x31c net/socket.c:1079 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x7c8/0xa2c fs/read_write.c:594 ksys_write+0x120/0x210 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+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 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