============================= WARNING: suspicious RCU usage 5.15.173-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.4.64/4804: #0: ffff88801ee41920 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1678 [inline] #0: ffff88801ee41920 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x1e/0x40 net/ipv4/tcp.c:1456 #1: ffffffff8c91fc60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #2: ffffffff8c91fcc0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #3: ffffffff8c91fcc0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #4: ffff88807c0c8908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #4: ffff88807c0c8908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3879 [inline] #4: ffff88807c0c8908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xc1f/0x32b0 net/core/dev.c:4221 #5: ffffffff8c91fc60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 stack backtrace: CPU: 0 PID: 4804 Comm: syz.4.64 Not tainted 5.15.173-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 qdisc_lookup+0xa8/0x630 net/sched/sch_api.c:304 qdisc_tree_reduce_backlog+0x212/0x4f0 net/sched/sch_api.c:800 cake_enqueue+0x21d7/0x8be0 net/sched/sch_cake.c:1775 qdisc_enqueue include/net/sch_generic.h:832 [inline] tbf_enqueue+0x345/0x6a0 net/sched/sch_tbf.c:237 dev_qdisc_enqueue+0x47/0x240 net/core/dev.c:3820 __dev_xmit_skb net/core/dev.c:3904 [inline] __dev_queue_xmit+0xe32/0x32b0 net/core/dev.c:4221 neigh_hh_output include/net/neighbour.h:493 [inline] neigh_output include/net/neighbour.h:507 [inline] ip_finish_output2+0xcd7/0x11a0 net/ipv4/ip_output.c:228 dst_output include/net/dst.h:443 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] __ip_queue_xmit+0x12df/0x1d90 net/ipv4/ip_output.c:532 __tcp_transmit_skb+0x1f39/0x3810 net/ipv4/tcp_output.c:1402 tcp_transmit_skb net/ipv4/tcp_output.c:1420 [inline] tcp_write_xmit+0x19e5/0x65f0 net/ipv4/tcp_output.c:2705 tcp_sendmsg_locked+0x20dc/0x3a90 net/ipv4/tcp.c:1410 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1457 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] __sys_sendto+0x564/0x720 net/socket.c:2063 __do_sys_sendto net/socket.c:2075 [inline] __se_sys_sendto net/socket.c:2071 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2071 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fa6552af819 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:00007fa653127038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007fa655466fa0 RCX: 00007fa6552af819 RDX: 994b6e03113064ae RSI: 0000000020000700 RDI: 0000000000000003 RBP: 00007fa65532275e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fa655466fa0 R15: 00007ffface12f28