=============================
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
10 locks held by udevd/4642:
#0: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#0: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xca/0x540 kernel/time/timer.c:1638
#1: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#2: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#3: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#4: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#5: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#6: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#7: ffffffff8c31eb00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#8: ffff88805e0f9108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#8: ffff88805e0f9108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3924 [inline]
#8: ffff88805e0f9108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xa2a/0x2f80 net/core/dev.c:4266
#9: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 0 PID: 4642 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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:832 [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
iptunnel_xmit+0x4d6/0x8e0 net/ipv4/ip_tunnel_core.c:82
udp_tunnel_xmit_skb+0x1b7/0x280 net/ipv4/udp_tunnel_core.c:175
geneve_xmit_skb drivers/net/geneve.c:1006 [inline]
geneve_xmit+0x2606/0x3420 drivers/net/geneve.c:1119
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [inline]
xmit_one net/core/dev.c:3662 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
__dev_queue_xmit+0x1a9b/0x2f80 net/core/dev.c:4305
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip6_finish_output2+0x1051/0x1510 net/ipv6/ip6_output.c:130
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xc2a/0x1500 net/ipv6/ndisc.c:513
addrconf_rs_timer+0x2d1/0x630 net/ipv6/addrconf.c:3956
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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 be a9 97 f7 48 89 df e8 f6 81 98 f7 e8 61 74 b9 f7 fb bf 01 00 00 00 a6 89 8c f7 65 8b 05 47 97 3c 76 85 c0 74 02 5b c3 e8 94 a4 3a
RSP: 0018:ffffc900033ef7f0 EFLAGS: 00000286
RAX: 9ad4de0ecb9a2a00 RBX: ffff888055938990 RCX: 9ad4de0ecb9a2a00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: 0000000000000001
RBP: dffffc0000000000 R08: ffff888055938993 R09: 1ffff1100ab27132
R10: dffffc0000000000 R11: ffffed100ab27133 R12: 00fff00000080017
R13: 0000000000000000 R14: ffff888055938988 R15: ffff888055938990
spin_unlock_irq include/linux/spinlock.h:414 [inline]
delete_from_page_cache+0x129/0x190 mm/filemap.c:267
truncate_inode_page+0x8d/0xb0 mm/truncate.c:219
shmem_undo_range+0x53c/0x1930 mm/shmem.c:960
shmem_truncate_range mm/shmem.c:1063 [inline]
shmem_evict_inode+0x220/0xa40 mm/shmem.c:1145
evict+0x4c9/0x8d0 fs/inode.c:647
__dentry_kill+0x431/0x650 fs/dcache.c:586
dentry_kill+0xb8/0x290 fs/dcache.c:-1
dput+0xd8/0x1a0 fs/dcache.c:893
__fput+0x5ee/0x930 fs/file_table.c:319
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: 0033:0x7f32f353a407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe5d006f90 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f32f344c880 RCX: 00007f32f353a407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007f32f344c6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 00005634f9996410 R14: 0000000000000008 R15: 00005634f9988840
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 66 90 add %ah,-0x70(%rsi)
5: 53 push %rbx
6: 48 89 fb mov %rdi,%rbx
9: 48 83 c7 18 add $0x18,%rdi
d: 48 8b 74 24 08 mov 0x8(%rsp),%rsi
12: e8 be a9 97 f7 call 0xf797a9d5
17: 48 89 df mov %rbx,%rdi
1a: e8 f6 81 98 f7 call 0xf7988215
1f: e8 61 74 b9 f7 call 0xf7b97485
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 a6 89 8c f7 call 0xf78c89d5 <-- trapping instruction
2f: 65 8b 05 47 97 3c 76 mov %gs:0x763c9747(%rip),%eax # 0x763c977d
36: 85 c0 test %eax,%eax
38: 74 02 je 0x3c
3a: 5b pop %rbx
3b: c3 ret
3c: e8 .byte 0xe8
3d: 94 xchg %eax,%esp
3e: a4 movsb %ds:(%rsi),%es:(%rdi)
3f: 3a .byte 0x3a