=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
9 locks held by kworker/u4:15/4959:
 #0: ffff88807b2a5138 ((wq_completion)bond0#7){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90003207d00 ((work_completion)(&(&bond->alb_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #3: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #4: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
 #5: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #6: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
 #7: ffff88807757b908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
 #7: ffff88807757b908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline]
 #7: ffff88807757b908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xa2a/0x2fd0 net/core/dev.c:4253
 #8: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312

stack backtrace:
CPU: 1 PID: 4959 Comm: kworker/u4:15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: bond0 bond_alb_monitor
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x190/0x430 net/sched/sch_api.c:783
 sfq_enqueue+0x14ad/0x2280 net/sched/sch_sfq.c:-1
 qdisc_enqueue include/net/sch_generic.h:832 [inline]
 tbf_enqueue+0x224/0x6e0 net/sched/sch_tbf.c:243
 dev_qdisc_enqueue+0x48/0x210 net/core/dev.c:3852
 __dev_xmit_skb net/core/dev.c:3936 [inline]
 __dev_queue_xmit+0xc25/0x2fd0 net/core/dev.c:4253
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip_finish_output2+0xc87/0x10a0 net/ipv4/ip_output.c:228
 iptunnel_xmit+0x4d6/0x8e0 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x1b7/0x280 net/ipv4/udp_tunnel_core.c:175
 geneve_xmit_skb drivers/net/geneve.c:1006 [inline]
 geneve_xmit+0x2606/0x3420 drivers/net/geneve.c:1119
 __netdev_start_xmit include/linux/netdevice.h:5036 [inline]
 netdev_start_xmit include/linux/netdevice.h:5050 [inline]
 xmit_one net/core/dev.c:3649 [inline]
 dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665
 __dev_queue_xmit+0x1a78/0x2fd0 net/core/dev.c:4288
 alb_send_learning_packets+0x125/0x2d0 drivers/net/bonding/bond_alb.c:1000
 bond_alb_monitor+0x3ab/0x1760 drivers/net/bonding/bond_alb.c:1528
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>