============================= 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 7 locks held by syz.6.1142/10870: #0: ffff888078e1a760 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline] #0: ffff888078e1a760 (sk_lock-AF_INET6){+.+.}-{0:0}, at: inet_stream_connect+0x4d/0xa0 net/ipv4/af_inet.c:735 #1: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #2: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #3: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #4: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #5: ffff888077750908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #5: ffff888077750908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3924 [inline] #5: ffff888077750908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xa2a/0x2f80 net/core/dev.c:4266 #6: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 stack backtrace: CPU: 0 PID: 10870 Comm: syz.6.1142 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: 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+0x1183/0x2280 net/sched/sch_sfq.c:471 qdisc_enqueue include/net/sch_generic.h:842 [inline] tbf_enqueue+0x224/0x6e0 net/sched/sch_tbf.c:243 dev_qdisc_enqueue+0x48/0x210 net/core/dev.c:3865 __dev_xmit_skb net/core/dev.c:3949 [inline] __dev_queue_xmit+0xc25/0x2f80 net/core/dev.c:4266 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 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434 dst_output include/net/dst.h:452 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] __ip_queue_xmit+0x11c1/0x1c00 net/ipv4/ip_output.c:538 __tcp_transmit_skb+0x1d11/0x3200 net/ipv4/tcp_output.c:1404 tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline] tcp_connect+0x21ac/0x4970 net/ipv4/tcp_output.c:3904 tcp_v4_connect+0x103e/0x1a80 net/ipv4/tcp_ipv4.c:323 tcp_v6_connect+0xb23/0x1a30 net/ipv6/tcp_ipv6.c:249 __inet_stream_connect+0x244/0xd70 net/ipv4/af_inet.c:672 inet_stream_connect+0x62/0xa0 net/ipv4/af_inet.c:736 __sys_connect_file net/socket.c:1932 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1949 __do_sys_connect net/socket.c:1959 [inline] __se_sys_connect net/socket.c:1956 [inline] __x64_sys_connect+0x76/0x80 net/socket.c:1956 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: 0033:0x7f8f17922dd9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8f15b5b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f8f17b9c090 RCX: 00007f8f17922dd9 RDX: 000000000000001c RSI: 0000200000000080 RDI: 0000000000000007 RBP: 00007f8f179b8d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8f17b9c128 R14: 00007f8f17b9c090 R15: 00007ffd449af908