============================= WARNING: suspicious RCU usage 5.15.189-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 6 locks held by syz.2.255/5023: #0: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #1: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #2: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #3: ffff8000143413c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #4: ffff0000cd5d8908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #4: ffff0000cd5d8908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline] #4: ffff0000cd5d8908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x840/0x2800 net/core/dev.c:4253 #5: ffff800014341360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 stack backtrace: CPU: 1 PID: 5023 Comm: syz.2.255 Not tainted 5.15.189-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 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 lockdep_rcu_suspicious+0x140/0x198 kernel/locking/lockdep.c:6574 qdisc_lookup+0xc8/0x64c net/sched/sch_api.c:304 qdisc_tree_reduce_backlog+0x188/0x410 net/sched/sch_api.c:793 cake_enqueue+0x1a3c/0x681c net/sched/sch_cake.c:1832 qdisc_enqueue include/net/sch_generic.h:832 [inline] tbf_enqueue+0x2dc/0x610 net/sched/sch_tbf.c:243 dev_qdisc_enqueue+0x5c/0x2fc net/core/dev.c:3852 __dev_xmit_skb net/core/dev.c:3936 [inline] __dev_queue_xmit+0xfc0/0x2800 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] ip_finish_output2+0xdac/0x1228 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:-1 [inline] ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x314/0x414 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:452 [inline] ip_local_out+0x120/0x15c net/ipv4/ip_output.c:126 iptunnel_xmit+0x3f8/0x8dc net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x181c/0x1f30 net/ipv4/ip_tunnel.c:838 ipip_tunnel_xmit+0x2ac/0x3e4 net/ipv4/ipip.c:307 __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 __dev_queue_xmit+0x12d8/0x2800 net/core/dev.c:4288 dev_queue_xmit+0x24/0x34 net/core/dev.c:4321 neigh_connected_output+0x32c/0x370 net/core/neighbour.c:1533 neigh_output include/net/neighbour.h:509 [inline] ip_finish_output2+0xdec/0x1228 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:-1 [inline] ip_finish_output+0x1b0/0x448 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x314/0x414 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:452 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0x134/0x2b0 net/ipv4/ip_output.c:1581 udp_send_skb+0x6e0/0x10bc net/ipv4/udp.c:991 udp_sendmsg+0x1414/0x1bac net/ipv4/udp.c:1279 udpv6_sendmsg+0x758/0x1ec0 net/ipv6/udp.c:1395 inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:667 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x61c/0x920 net/socket.c:2436 ___sys_sendmsg+0x1d0/0x240 net/socket.c:2490 __sys_sendmmsg+0x218/0x5f0 net/socket.c:2576 __do_sys_sendmmsg net/socket.c:2605 [inline] __se_sys_sendmmsg net/socket.c:2602 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2602 __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 loop2: detected capacity change from 0 to 1024 hfsplus: request for non-existent node 16777216 in B*Tree hfsplus: request for non-existent node 16777216 in B*Tree hfsplus: request for non-existent node 16777216 in B*Tree hfsplus: request for non-existent node 16777216 in B*Tree hfsplus: request for non-existent node 16777216 in B*Tree hfsplus: request for non-existent node 16777216 in B*Tree