============================= 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.0.163/5136: #0: ffff888060d44410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline] #0: ffff888060d44410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:650 [inline] #0: ffff888060d44410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x90/0x240 net/socket.c:1346 #1: ffff88807d4dd520 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline] #1: ffff88807d4dd520 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_close+0x19/0x110 net/ipv4/tcp.c:2922 #2: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #3: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #4: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #5: ffff888073b38108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #5: ffff888073b38108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline] #5: ffff888073b38108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xb8a/0x2ed0 net/core/dev.c:4253 #6: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 stack backtrace: CPU: 0 PID: 5136 Comm: syz.0.163 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x168/0x230 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 pfifo_tail_enqueue+0x372/0x4d0 net/sched/sch_fifo.c:54 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+0xd7e/0x2ed0 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+0xc69/0x1080 net/ipv4/ip_output.c:228 dst_output include/net/dst.h:452 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] __ip_queue_xmit+0x11c3/0x1c00 net/ipv4/ip_output.c:532 __tcp_transmit_skb+0x1ced/0x31c0 net/ipv4/tcp_output.c:1404 tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline] tcp_send_active_reset+0x376/0x6f0 net/ipv4/tcp_output.c:3498 __tcp_close+0x4bf/0xfa0 net/ipv4/tcp.c:2798 tcp_close+0x24/0x110 net/ipv4/tcp.c:2923 inet_release+0x139/0x180 net/ipv4/af_inet.c:432 __sock_release net/socket.c:651 [inline] sock_close+0xd5/0x240 net/socket.c:1346 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f0b1520f749 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:00007ffc5f30e158 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 000000000001b70d RCX: 00007f0b1520f749 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f0b15467da0 R08: 0000000000000001 R09: 000000145f30e44f R10: 0000001b31120000 R11: 0000000000000246 R12: 00007f0b15465fac R13: 00007f0b15465fa0 R14: ffffffffffffffff R15: 00007ffc5f30e270