bond4: (slave gretap1): making interface the new active one ============================================ WARNING: possible recursive locking detected syzkaller #0 Tainted: G L -------------------------------------------- syz.3.8482/27365 is trying to acquire lock: ffff888039db0198 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline] ffff888039db0198 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] ffff888039db0198 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 but task is already holding lock: ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline] ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{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#4); lock(&qdisc_xmit_lock_key#4); *** DEADLOCK *** May be due to missing lock nesting notation 17 locks held by syz.3.8482/27365: #0: ffffffff8edcacf8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8edcacf8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8edcacf8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570 #1: ffffffff8e8a5938 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #1: ffffffff8e8a5938 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline] #1: ffffffff8e8a5938 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8ec/0x1c90 net/core/rtnetlink.c:4071 #2: ffffffff8d44eac0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #3: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #4: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #4: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #4: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x253/0x3210 net/core/dev.c:4744 #5: ffff88805f39e328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:202 [inline] #5: ffff88805f39e328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4156 [inline] #5: ffff88805f39e328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_queue_xmit+0xeb1/0x3210 net/core/dev.c:4785 #6: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #6: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: __rt_spin_trylock kernel/locking/spinlock_rt.c:110 [inline] #6: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x10d/0x2b0 kernel/locking/spinlock_rt.c:118 #7: ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline] #7: ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4710 [inline] #7: ffff88805b54c998 (&qdisc_xmit_lock_key#4){+...}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 #8: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #8: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #8: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #8: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1c1/0x3e0 kernel/locking/spinlock_rt.c:57 #9: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #9: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: ip_output+0x5b/0x450 net/ipv4/ip_output.c:433 #10: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #10: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #10: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x3d0/0x1060 net/ipv4/ip_output.c:230 #11: ffffffff8d44eac0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #12: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #12: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #12: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: arp_xmit+0x23/0x270 net/ipv4/arp.c:663 #13: ffffffff8d44eac0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #14: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #14: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #14: ffffffff8d5ae9a0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x253/0x3210 net/core/dev.c:4744 #15: ffff88805ea18328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:202 [inline] #15: ffff88805ea18328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4156 [inline] #15: ffff88805ea18328 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_queue_xmit+0xeb1/0x3210 net/core/dev.c:4785 #16: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #16: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #16: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: __rt_spin_trylock kernel/locking/spinlock_rt.c:110 [inline] #16: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x10d/0x2b0 kernel/locking/spinlock_rt.c:118 stack backtrace: CPU: 1 UID: 0 PID: 27365 Comm: syz.3.8482 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP 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 rt_spin_lock+0x88/0x3e0 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:44 [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+0x134f/0x3210 net/core/dev.c:4785 NF_HOOK+0x310/0x3a0 include/linux/netfilter.h:-1 arp_xmit+0x16c/0x270 net/ipv4/arp.c:665 arp_solicit+0xc27/0xe80 net/ipv4/arp.c:392 neigh_probe net/core/neighbour.c:1097 [inline] __neigh_event_send+0xf3a/0x1540 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+0x19f/0x780 net/core/neighbour.c:1578 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xc06/0x1060 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+0x1c44/0x2390 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+0x2e0/0x840 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+0x134f/0x3210 net/core/dev.c:4785 dev_queue_xmit include/linux/netdevice.h:3381 [inline] alb_send_lp_vid+0x328/0x530 drivers/net/bonding/bond_alb.c:949 alb_send_learning_packets+0x10d/0x2c0 drivers/net/bonding/bond_alb.c:1012 bond_alb_handle_active_change+0xa1b/0xed0 drivers/net/bonding/bond_alb.c:1779 bond_change_active_slave+0x107b/0x36a0 drivers/net/bonding/bond_main.c:1256 bond_select_active_slave+0x8d2/0xce0 drivers/net/bonding/bond_main.c:1336 bond_enslave+0x2341/0x3ac0 drivers/net/bonding/bond_main.c:2195 do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2963 rtnl_newlink_create+0x677/0xb00 net/core/rtnetlink.c:3854 __rtnl_newlink net/core/rtnetlink.c:3957 [inline] rtnl_newlink+0x16e7/0x1c90 net/core/rtnetlink.c:4072 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 ____sys_sendmsg+0x508/0x810 net/socket.c:2592 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2681 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: 0033:0x7f8ab1bdf749 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:00007f8aafe04038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f8ab1e36180 RCX: 00007f8ab1bdf749 RDX: 0000000000000040 RSI: 00002000000000c0 RDI: 0000000000000005 RBP: 00007f8ab1c63f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8ab1e36218 R14: 00007f8ab1e36180 R15: 00007ffd3204ca38 bond4: (slave gretap1): Enslaving as an active interface with an up link syz.3.8482 (27365) used greatest stack depth: 16584 bytes left