rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (1 GPs behind) idle=dec4/1/0x4000000000000000 softirq=35399/35400 fqs=3880
rcu: hardirqs softirqs csw/system
rcu: number: 1354233 0 0
rcu: cputime: 16364 36125 62 ==> 52520(ms)
rcu: (t=10503 jiffies g=47213 q=1880 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 1578 jiffies! g47213 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=35762
rcu: rcu_preempt kthread starved for 1581 jiffies! g47213 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:26984 pid:17 ppid:2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8501 Comm: kworker/u4:25 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
RIP: 0010:queued_write_lock_slowpath+0x137/0x2ac kernel/locking/qrwlock.c:85
Code: f0 41 81 0e 00 01 00 00 42 0f b6 04 23 84 c0 74 37 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 2a 4c 89 f7 e8 1d 68 50 f7 eb 20 f3 90 <42> 0f b6 04 23 84 c0 74 15 44 89 f1 80 e1 07 80 c1 03 38 c1 7c 08
RSP: 0018:ffffc9000bb7f3a0 EFLAGS: 00000206
RAX: 00000000000001ff RBX: 1ffff1100508cc05 RCX: ffffffff8a8ee2ed
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888028466028
RBP: ffffc9000bb7f450 R08: ffff88802846602b R09: 1ffff1100508cc05
R10: dffffc0000000000 R11: ffffed100508cc06 R12: dffffc0000000000
R13: 1ffff9200176fe78 R14: ffff888028466028 R15: ffffc9000bb7f3f0
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557eab4aca38 CR3: 000000000cf32000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
queued_write_lock include/asm-generic/qrwlock.h:101 [inline]
do_raw_write_lock+0x1ea/0x260 kernel/locking/spinlock_debug.c:210
__neigh_event_send+0x3b/0x1440 net/core/neighbour.c:1182
neigh_event_send_probe include/net/neighbour.h:467 [inline]
neigh_event_send include/net/neighbour.h:473 [inline]
neigh_resolve_output+0x19b/0x730 net/core/neighbour.c:1552
neigh_output include/net/neighbour.h:543 [inline]
ip6_finish_output2+0xe3d/0x1630 net/ipv6/ip6_output.c:141
ip6tunnel_xmit include/net/ip6_tunnel.h:161 [inline]
udp_tunnel6_xmit_skb+0x53e/0x970 net/ipv6/ip6_udp_tunnel.c:109
send6+0x5ea/0x920 drivers/net/wireguard/socket.c:152
wg_socket_send_skb_to_peer+0x111/0x1c0 drivers/net/wireguard/socket.c:178
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x207/0x350 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2653 [inline]
process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
CPU: 0 PID: 11363 Comm: syz.3.1479 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:get_stack_info_noinstr+0x2d/0x130 arch/x86/kernel/dumpstack_64.c:176
Code: 00 41 57 41 56 41 55 41 54 53 49 89 d6 49 89 f4 49 89 ff e8 15 01 00 00 b3 01 84 c0 0f 85 d0 00 00 00 65 48 8b 05 03 cc 7e 75 <49> 39 c4 74 07 31 db e9 bc 00 00 00 48 c7 c7 26 05 87 8c e8 8b 40
RSP: 0018:ffffc90000007598 EFLAGS: 00000246
RAX: ffff88807c1b5a00 RBX: ffffc90000007601 RCX: ffffc9000bb58000
RDX: ffffc90000007668 RSI: ffffc9000bb60000 RDI: ffffc90000007600
RBP: dffffc0000000000 R08: ffffc90000007600 R09: 0000000000000000
R10: ffffc90000007668 R11: fffff52000000ed9 R12: ffff88807c1b5a00
R13: ffffc90000007688 R14: ffffc90000007668 R15: ffffc90000007600
FS: 00007fc0df10e6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000100000000 CR3: 000000002cce8000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
get_stack_info+0x40/0x170 arch/x86/kernel/dumpstack_64.c:199
__unwind_start+0x48b/0x7e0 arch/x86/kernel/unwind_orc.c:729
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
kmem_cache_free+0xf8/0x270 mm/slub.c:3852
__skb_queue_purge_reason include/linux/skbuff.h:3245 [inline]
__skb_queue_purge include/linux/skbuff.h:3250 [inline]
neigh_invalidate+0x394/0x450 net/core/neighbour.c:1067
neigh_timer_handler+0x914/0xff0 net/core/neighbour.c:1151
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x542/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:preempt_schedule_irq+0xba/0x150 kernel/sched/core.c:7010
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 6f bf 01 00 00 00 e8 51 2b cf f6 e8 7c 32 00 f7 fb bf 01 00 00 00 f1 b4 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc9000bb5fba0 EFLAGS: 00000286
RAX: c1887183cb390e00 RBX: 0000000000000000 RCX: c1887183cb390e00
RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: 0000000000000001
RBP: ffffc9000bb5fc50 R08: ffffffff911c15a7 R09: 1ffffffff22382b4
R10: dffffc0000000000 R11: fffffbfff22382b5 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff9200176bf74
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__mutex_unlock_slowpath+0x6a6/0x6c0 kernel/locking/mutex.c:952
Code: 45 49 c7 04 04 00 00 00 00 49 c7 44 04 08 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 84 24 a0 00 00 00 75 0f 48 8d 65 d8 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 e8 6b 63 f7 ff 66 2e 0f 1f 84 00 00
RSP: 0018:ffffc9000bb5fd10 EFLAGS: 00000246
RAX: c1887183cb390e00 RBX: ffff888027178000 RCX: ffffffff8a8daad4
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000bb5fcc0
RBP: ffffc9000bb5fd30 R08: ffffc9000bb5fcc7 R09: 1ffff9200176bf98
R10: dffffc0000000000 R11: fffff5200176bf99 R12: 1ffff9200176bf8c
R13: ffff888027178040 R14: 1ffffffff1d16476 R15: ffffc9000bb5fcc0
__do_sys_perf_event_open kernel/events/core.c:12918 [inline]
__se_sys_perf_event_open+0x1848/0x1c50 kernel/events/core.c:12567
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc0de19c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc0df10e028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007fc0de415fa0 RCX: 00007fc0de19c799
RDX: ffffff7fffffffff RSI: 0000000000000000 RDI: 0000200000000480
RBP: 00007fc0de232c99 R08: 0000000000000008 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc0de416038 R14: 00007fc0de415fa0 R15: 00007fffc9a59e08