============================= WARNING: suspicious RCU usage 5.15.169-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 11 locks held by kworker/0:6/4082: #0: ffff0000d3400938 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2283 #1: ffff8000203a7c00 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2285 #2: ffff0000e63c8530 (&idev->mc_lock){+.+.}-{3:3}, at: mld_ifc_work+0x3c/0xb9c net/ipv6/mcast.c:2652 #3: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #4: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #5: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #6: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 #7: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #8: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #9: ffff0000d8fa4908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #9: ffff0000d8fa4908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3875 [inline] #9: ffff0000d8fa4908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x8a0/0x2ac8 net/core/dev.c:4217 #10: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 stack backtrace: CPU: 0 PID: 4082 Comm: kworker/0:6 Not tainted 5.15.169-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: mld mld_ifc_work Call trace: dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 lockdep_rcu_suspicious+0x188/0x1e0 kernel/locking/lockdep.c:6571 qdisc_lookup+0xc8/0x64c net/sched/sch_api.c:304 qdisc_tree_reduce_backlog+0x200/0x4e8 net/sched/sch_api.c:800 pfifo_tail_enqueue+0x280/0x38c net/sched/sch_fifo.c:51 qdisc_enqueue include/net/sch_generic.h:832 [inline] tbf_enqueue+0x2f8/0x5f0 net/sched/sch_tbf.c:237 dev_qdisc_enqueue+0x60/0x35c net/core/dev.c:3816 __dev_xmit_skb net/core/dev.c:3900 [inline] __dev_queue_xmit+0x1018/0x2ac8 net/core/dev.c:4217 dev_queue_xmit+0x24/0x34 net/core/dev.c:4285 neigh_hh_output include/net/neighbour.h:493 [inline] neigh_output include/net/neighbour.h:507 [inline] ip_finish_output2+0xd3c/0x131c net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x218 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x330/0x49c net/ipv4/ip_output.c:430 dst_output include/net/dst.h:443 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126 iptunnel_xmit+0x40c/0x8fc net/ipv4/ip_tunnel_core.c:82 udp_tunnel_xmit_skb+0x178/0x284 net/ipv4/udp_tunnel_core.c:175 geneve_xmit_skb drivers/net/geneve.c:1006 [inline] geneve_xmit+0x24cc/0x323c drivers/net/geneve.c:1119 __netdev_start_xmit include/linux/netdevice.h:5019 [inline] netdev_start_xmit include/linux/netdevice.h:5033 [inline] xmit_one net/core/dev.c:3617 [inline] dev_hard_start_xmit+0x2bc/0x92c net/core/dev.c:3633 __dev_queue_xmit+0x1378/0x2ac8 net/core/dev.c:4252 dev_queue_xmit+0x24/0x34 net/core/dev.c:4285 neigh_hh_output include/net/neighbour.h:493 [inline] neigh_output include/net/neighbour.h:507 [inline] ip6_finish_output2+0x132c/0x1cec net/ipv6/ip6_output.c:130 __ip6_finish_output+0x580/0x6ec 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+0x274/0x594 net/ipv6/ip6_output.c:234 dst_output include/net/dst.h:443 [inline] NF_HOOK+0x160/0x4ec include/linux/netfilter.h:302 mld_sendpack+0x828/0x1264 net/ipv6/mcast.c:1820 mld_send_cr net/ipv6/mcast.c:2121 [inline] mld_ifc_work+0x85c/0xb9c net/ipv6/mcast.c:2653 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310 worker_thread+0x910/0x1034 kernel/workqueue.c:2457 kthread+0x37c/0x45c kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870