============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/4642 is trying to acquire lock: ffff8880253bf098 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] ffff8880253bf098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] ffff8880253bf098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1438/0x2ed0 net/core/dev.c:4284 but task is already holding lock: ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x156/0x4a0 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 10 locks held by syz-executor.0/4642: #0: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 #1: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #2: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #3: ffff888066c64258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline] #3: ffff888066c64258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline] #3: ffff888066c64258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline] #3: ffff888066c64258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253 #4: ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #4: ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4437 [inline] #4: ffff888021edf898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x156/0x4a0 net/sched/sch_generic.c:340 #5: ffff88802ad0f4a0 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline] #5: ffff88802ad0f4a0 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:118 [inline] #5: ffff88802ad0f4a0 (k-slock-AF_INET6){+...}-{2:2}, at: icmp6_send+0xa93/0x16e0 net/ipv6/icmp.c:551 #6: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 #7: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #8: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #9: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 stack backtrace: CPU: 1 PID: 4642 Comm: syz-executor.0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 __lock_acquire+0x1227/0x7c60 kernel/locking/lockdep.c:-1 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:364 [inline] __netif_tx_lock include/linux/netdevice.h:4437 [inline] __dev_queue_xmit+0x1438/0x2ed0 net/core/dev.c:4284 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130 ip6_send_skb+0x1b9/0x360 net/ipv6/ip6_output.c:1951 icmp6_send+0x113e/0x16e0 net/ipv6/icmp.c:630 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x35/0x490 net/ipv6/route.c:2788 ip_tunnel_xmit+0xea1/0x2240 net/ipv4/ip_tunnel.c:844 __gre_xmit net/ipv4/ip_gre.c:474 [inline] erspan_xmit+0x9d5/0x15a0 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+0x2a5/0x7e0 net/core/dev.c:3665 sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x170e/0x2ed0 net/core/dev.c:4253 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130 dst_output include/net/dst.h:452 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] rawv6_send_hdrinc+0xdb0/0x16c0 net/ipv6/raw.c:691 rawv6_sendmsg+0x1143/0x1710 net/ipv6/raw.c:949 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2436 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2490 __sys_sendmmsg+0x27c/0x4a0 net/socket.c:2576 __do_sys_sendmmsg net/socket.c:2605 [inline] __se_sys_sendmmsg net/socket.c:2602 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2602 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc4d1058da9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc4d03d90c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007fc4d1186f80 RCX: 00007fc4d1058da9 RDX: 0000000000000002 RSI: 0000000020001e80 RDI: 0000000000000005 RBP: 00007fc4d10a547a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fc4d1186f80 R15: 00007ffd71f745d8