[v6.1] INFO: rcu detected stall in neigh_timer_handler (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 882efbdd9d34 Linux 6.1.155
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1328d542580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=6b1a8eba412cd823d5da
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9e95032679d0/disk-882efbdd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a435805a627b/vmlinux-882efbdd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d15d65ba922d/bzImage-882efbdd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6b1a8e...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2665 jiffies s: 14713 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6599 Comm: syz.6.499 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:244 [inline]
RIP: 0010:__sanitizer_cov_trace_cmp4+0x4/0x80 kernel/kcov.c:287
Code: 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 02 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 90 48 8b 04 24 <65> 48 8b 15 e4 9e 81 7e 65 8b 0d e5 9e 81 7e 81 e1 00 01 ff 00 74
RSP: 0018:ffffc90000006c18 EFLAGS: 00000046
RAX: ffffffff8170f731 RBX: ffff8880b8e2a648 RCX: ffff88801ee4bb80
RDX: 0000000000010100 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffffc90000006d90 R08: dffffc0000000000 R09: fffffbfff1c3ecb6
R10: fffffbfff1c3ecb6 R11: 1ffffffff1c3ecb5 R12: ffff888074eded60
R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
FS: 00007f16662756c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f00ca4b6048 CR3: 0000000056c21000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0100000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
cpu_max_bits_warn include/linux/cpumask.h:110 [inline]
cpumask_check include/linux/cpumask.h:117 [inline]
cpumask_test_cpu include/linux/cpumask.h:444 [inline]
cpu_online include/linux/cpumask.h:1030 [inline]
trace_hrtimer_expire_exit include/trace/events/timer.h:286 [inline]
__run_hrtimer kernel/time/hrtimer.c:1750 [inline]
__hrtimer_run_queues+0x5b1/0xd60 kernel/time/hrtimer.c:1811
hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:seqcount_lockdep_reader_access+0x17b/0x1c0 include/linux/seqlock.h:105
Code: 00 4d 85 e4 75 16 e8 04 8f 0f 00 eb 15 e8 fd 8e 0f 00 e8 b8 52 a6 08 4d 85 e4 74 ea e8 ee 8e 0f 00 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 66 43 c7 44 3e 09 00 00 43 c6 44 3e 0b 00
RSP: 0018:ffffc90000006fc0 EFLAGS: 00000246
RAX: ffffffff81714002 RBX: 0000000000000000 RCX: ffff88801ee4bb80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000007078 R08: dffffc0000000000 R09: fffffbfff215c45b
R10: fffffbfff215c45b R11: 1ffffffff215c45a R12: 0000000000000200
R13: 000001fb63109b96 R14: 1ffff92000000df8 R15: dffffc0000000000
ktime_get_with_offset+0x90/0x320 kernel/time/timekeeping.c:889
ktime_get_real include/linux/timekeeping.h:79 [inline]
netif_rx_internal+0x398/0x560 net/core/dev.c:5023
__netif_rx+0x74/0xb0 net/core/dev.c:5066
loopback_xmit+0x473/0x6e0 drivers/net/loopback.c:89
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3670 [inline]
dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3686
__dev_queue_xmit+0x1bf1/0x3760 net/core/dev.c:4346
dev_queue_xmit include/linux/netdevice.h:3051 [inline]
neigh_hh_output include/net/neighbour.h:529 [inline]
neigh_output include/net/neighbour.h:543 [inline]
ip_finish_output2+0xbe8/0x11b0 net/ipv4/ip_output.c:228
dst_output include/net/dst.h:453 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
ip_send_skb+0x129/0x1c0 net/ipv4/ip_output.c:1600
__icmp_send+0xfbb/0x1320 net/ipv4/icmp.c:785
ipv4_send_dest_unreach net/ipv4/route.c:1258 [inline]
ipv4_link_failure+0x65c/0xa10 net/ipv4/route.c:1265
dst_link_failure include/net/dst.h:423 [inline]
arp_error_report+0x10e/0x160 net/ipv4/arp.c:296
neigh_invalidate+0x22c/0x450 net/core/neighbour.c:1064
neigh_timer_handler+0x911/0x1080 net/core/neighbour.c:1151
call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504
expire_timers kernel/time/timer.c:1549 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1820
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5123
Code: 0f 84 3b 01 00 00 48 85 db 0f 85 5a 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 40 30 c9 08 e8 8b b1 2e 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90003b3f458 EFLAGS: 00000282
RAX: 73e7338d569f4800 RBX: 0000000000000000 RCX: 73e7338d569f4800
RDX: dffffc0000000000 RSI: ffffffff8a8c0500 RDI: ffffffff8adefd20
RBP: ffffc90003b3f4b0 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: ffff88801ee4bb80
R13: dffffc0000000000 R14: ffff88802e4d8000 R15: ffff8880b8e3b590
context_switch kernel/sched/core.c:5247 [inline]
__schedule+0x10f4/0x40b0 kernel/sched/core.c:6561
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
__text_poke+0x680/0x810 arch/x86/kernel/alternative.c:1456
text_poke arch/x86/kernel/alternative.c:1480 [inline]
text_poke_bp_batch+0x597/0x7d0 arch/x86/kernel/alternative.c:1852
text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
text_poke_queue+0xab/0x180 arch/x86/kernel/alternative.c:1984
arch_jump_label_transform_queue+0x6a/0xd0 arch/x86/kernel/jump_label.c:138
__jump_label_update+0x17d/0x390 kernel/jump_label.c:510
static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207
static_key_enable+0x16/0x20 kernel/jump_label.c:220
tracepoint_add_func+0x83b/0x9a0 kernel/tracepoint.c:361
tracepoint_probe_register_prio kernel/tracepoint.c:511 [inline]
tracepoint_probe_register+0x5a/0x90 kernel/tracepoint.c:531
perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
perf_trace_event_init+0x420/0x940 kernel/trace/trace_event_perf.c:202
perf_trace_init+0x234/0x2d0 kernel/trace/trace_event_perf.c:226
perf_tp_event_init+0x89/0x110 kernel/events/core.c:10084
perf_try_init_event+0x12b/0x3d0 kernel/events/core.c:11594
perf_init_event kernel/events/core.c:11658 [inline]
perf_event_alloc+0xf5c/0x21b0 kernel/events/core.c:11950
__do_sys_perf_event_open kernel/events/core.c:12486 [inline]
__se_sys_perf_event_open+0x6cd/0x1e60 kernel/events/core.c:12378
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f166538eec9
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:00007f1666275038 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f16655e5fa0 RCX: 00007f166538eec9
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000000
RBP: 00007f1665411f91 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f16655e6038 R14: 00007f16655e5fa0 R15: 00007ffc6202e8d8
</TASK>


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