=============================
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
8 locks held by syz-executor/4190:
#0: ffffc90000007be0 ((&icsk->icsk_retransmit_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#0: ffffc90000007be0 ((&icsk->icsk_retransmit_timer)){+.-.}-{0:0}, at: call_timer_fn+0xca/0x540 kernel/time/timer.c:1638
#1: ffff88802a0460a0 (slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#1: ffff88802a0460a0 (slock-AF_INET){+.-.}-{2:2}, at: tcp_write_timer+0x29/0x280 net/ipv4/tcp_timer.c:673
#2: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#3: ffffffff8c31eb20 (rcu_read_lock){....}-{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: ffffffff8c31eb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#6: ffff8880249b3908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#6: ffff8880249b3908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3924 [inline]
#6: ffff8880249b3908 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xa2a/0x2f80 net/core/dev.c:4266
#7: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 0 PID: 4190 Comm: syz-executor 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
fq_codel_enqueue+0x105e/0x1600 net/sched/sch_fq_codel.c:243
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_write_wakeup+0x893/0xd90 net/ipv4/tcp_output.c:4107
tcp_send_probe0+0x4d/0x450 net/ipv4/tcp_output.c:4129
tcp_probe_timer net/ipv4/tcp_timer.c:395 [inline]
tcp_write_timer_handler+0x686/0x9a0 net/ipv4/tcp_timer.c:659
tcp_write_timer+0x126/0x280 net/ipv4/tcp_timer.c:675
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1699 [inline]
__run_timers+0x53e/0x800 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x339/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804
Code: be ff ff ff ff e8 3c 62 68 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 e6 cd 71 08 e8 61 e6 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c
RSP: 0000:ffffc90002f9fa08 EFLAGS: 00000282
RAX: 06927be2b18be400 RBX: ffff8880b903a340 RCX: 06927be2b18be400
RDX: dffffc0000000000 RSI: ffffffff8a2b2800 RDI: ffffffff8a79fe40
RBP: 1ffff11017207613 R08: ffff8880b903a343 R09: 1ffff11017207468
R10: dffffc0000000000 R11: ffffed1017207469 R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921
context_switch kernel/sched/core.c:5052 [inline]
__schedule+0x11f7/0x43c0 kernel/sched/core.c:6395
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:__filename_parentat+0x0/0x690 fs/namei.c:2527
Code: 89 ee 89 ea 4c 89 e1 4d 89 f8 4d 89 f1 53 e8 17 00 00 00 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 84 00 00 00 00 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec c0 01
RSP: 0018:ffffc90002f9fdf0 EFLAGS: 00000202
RAX: ffffc90002f9fe01 RBX: ffff88805fe91100 RCX: ffffc90002f9fe60
RDX: 0000000000000000 RSI: ffff88805fe91100 RDI: 00000000ffffff9c
RBP: ffffc90002f9ff00 R08: ffffc90002f9fe80 R09: ffffc90002f9fe3c
R10: dffffc0000000000 R11: fffff520005f3fd2 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88805fe91100 R15: ffffc90002f9fe60
filename_parentat fs/namei.c:2552 [inline]
do_unlinkat+0xfc/0x710 fs/namei.c:4327
__do_sys_unlink fs/namei.c:4404 [inline]
__se_sys_unlink fs/namei.c:4402 [inline]
__x64_sys_unlink+0x45/0x50 fs/namei.c:4402
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: 0033:0x7f527b9f9ec7
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffea138d2e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f527b9f9ec7
RDX: 00007ffea138d310 RSI: 00007ffea138d3a0 RDI: 00007ffea138d3a0
RBP: 00007ffea138d3a0 R08: 00007ffea138e3a0 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffea138e430
R13: 00007f527ba90120 R14: 0000000000023d15 R15: 00007ffea138e470
----------------
Code disassembly (best guess):
0: be ff ff ff ff mov $0xffffffff,%esi
5: e8 3c 62 68 08 call 0x8686246
a: 85 c0 test %eax,%eax
c: 74 4a je 0x58
e: 4d 85 ff test %r15,%r15
11: 75 66 jne 0x79
13: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
18: 48 89 df mov %rbx,%rdi
1b: e8 e6 cd 71 08 call 0x871ce06
20: e8 61 e6 2a 00 call 0x2ae686
25: fb sti
26: 48 83 c4 08 add $0x8,%rsp
* 2a: 5b pop %rbx <-- trapping instruction
2b: 41 5c pop %r12
2d: 41 5d pop %r13
2f: 41 5e pop %r14
31: 41 5f pop %r15
33: 5d pop %rbp
34: c3 ret
35: 48 89 df mov %rbx,%rdi
38: e8 c9 09 fe ff call 0xfffe0a06
3d: 43 rex.XB
3e: 80 .byte 0x80
3f: 3c .byte 0x3c