rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (1 GPs behind) idle=9cfc/1/0x4000000000000000 softirq=83050/83052 fqs=7
rcu: (t=10501 jiffies g=70509 q=1504 ncpus=2)
rcu: rcu_preempt kthread starved for 8195 jiffies! g70509 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:27784 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7058
schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:task_wait_context kernel/locking/lockdep.c:4790 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4875 [inline]
RIP: 0010:__lock_acquire+0x73b/0x1ce0 kernel/locking/lockdep.c:5187
Code: 12 0f 85 9a 0f 00 00 48 83 c4 70 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 41 83 bd d4 0a 00 00 01 19 d2 83 e2 02 83 c2 03 a2 fb ff ff 45 31 f6 e9 6b fb ff ff 8b 0c 24 85 c9 0f 85 4c fc
RSP: 0000:ffffc90000a07f68 EFLAGS: 00000006
RAX: 0000000000000000 RBX: ffff88801e2e2f30 RCX: 0000000000000025
RDX: 0000000000000003 RSI: 0000000000000005 RDI: ffff88801e2e2ff8
RBP: 0000000000000000 R08: 0000000000080000 R09: 0000000000000001
R10: 00000000000000c8 R11: 0000000000000001 R12: ffff88801e2e2ff8
R13: ffff88801e2e2440 R14: 0000000000000000 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8881247b9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e66eaa060 CR3: 000000004525b000 CR4: 00000000003526f0
Call Trace:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
local_lock_acquire include/linux/local_lock_internal.h:38 [inline]
get_random_u16+0x102/0x7e0 drivers/char/random.c:553
cake_get_flow_quantum+0xd9/0x290 net/sched/sch_cake.c:687
cake_dequeue+0x1be7/0x4830 net/sched/sch_cake.c:2119
dequeue_skb net/sched/sch_generic.c:294 [inline]
qdisc_restart net/sched/sch_generic.c:399 [inline]
__qdisc_run+0x1bd/0x1bf0 net/sched/sch_generic.c:417
__dev_xmit_skb net/core/dev.c:4183 [inline]
__dev_queue_xmit+0x2b43/0x4490 net/core/dev.c:4691
dev_queue_xmit include/linux/netdevice.h:3361 [inline]
neigh_hh_output include/net/neighbour.h:531 [inline]
neigh_output include/net/neighbour.h:545 [inline]
ip6_finish_output2+0xe98/0x2020 net/ipv6/ip6_output.c:141
__ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:215
ip6_finish_output net/ipv6/ip6_output.c:226 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x1ca/0x3e0 net/ipv6/ip6_output.c:248
dst_output include/net/dst.h:461 [inline]
ip6_local_out+0xd1/0x4d0 net/ipv6/output_core.c:155
ip6tunnel_xmit include/net/ip6_tunnel.h:162 [inline]
udp_tunnel6_xmit_skb+0x7f1/0xc50 net/ipv6/ip6_udp_tunnel.c:112
tipc_udp_xmit+0x219/0xdf0 net/tipc/udp_media.c:220
tipc_udp_send_msg+0x292/0x4a0 net/tipc/udp_media.c:271
tipc_bearer_xmit_skb+0x1bd/0x430 net/tipc/bearer.c:575
tipc_disc_timeout+0x5b2/0x850 net/tipc/discover.c:338
call_timer_fn+0x197/0x620 kernel/time/timer.c:1747
expire_timers kernel/time/timer.c:1798 [inline]
__run_timers+0x6ef/0x960 kernel/time/timer.c:2372
__run_timer_base kernel/time/timer.c:2384 [inline]
__run_timer_base kernel/time/timer.c:2376 [inline]
run_timer_base+0x114/0x190 kernel/time/timer.c:2393
run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2403
handle_softirqs+0x216/0x8e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x109/0x170 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 4c 62 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 52 16 00 fb f4 4c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0000:ffffc90000197df8 EFLAGS: 000002c2
RAX: 000000000d7a71a1 RBX: 0000000000000001 RCX: ffffffff8b93bc29
RDX: 0000000000000000 RSI: ffffffff8de50210 RDI: ffffffff8c162900
RBP: ffffed1003c5c488 R08: 0000000000000001 R09: ffffed10170a6655
R10: ffff8880b85332ab R11: 0000000000000000 R12: 0000000000000001
R13: ffff88801e2e2440 R14: ffffffff90ab4b90 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:757
default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x391/0x510 kernel/sched/idle.c:330
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
common_startup_64+0x13e/0x148
CPU: 0 UID: 0 PID: 12340 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 4c 62 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 52 16 00 fb f4 4c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc900000070b8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000002
RDX: ffff888077f0a440 RSI: ffffffff816a3d21 RDI: ffffffff8c162900
RBP: ffff8880745a00f0 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90ab4b97 R11: 0000000000000000 R12: 0000000000000003
R13: 0000000000000003 R14: ffff8880b843b280 R15: ffffed100e8b401e
FS: 0000000000000000(0000) GS:ffff8881246b9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9afabc3430 CR3: 0000000048dea000 CR4: 00000000003526f0
Call Trace:
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
kvm_wait arch/x86/kernel/kvm.c:1064 [inline]
kvm_wait+0x186/0x1f0 arch/x86/kernel/kvm.c:1046
pv_wait arch/x86/include/asm/paravirt.h:569 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:466 [inline]
__pv_queued_spin_lock_slowpath+0x4e1/0xcf0 kernel/locking/qspinlock.c:325
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:557 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x20e/0x2b0 kernel/locking/spinlock_debug.c:116
spin_lock include/linux/spinlock.h:351 [inline]
__dev_xmit_skb net/core/dev.c:4150 [inline]
__dev_queue_xmit+0x20e2/0x4490 net/core/dev.c:4691
dev_queue_xmit include/linux/netdevice.h:3361 [inline]
neigh_hh_output include/net/neighbour.h:531 [inline]
neigh_output include/net/neighbour.h:545 [inline]
ip6_finish_output2+0xe98/0x2020 net/ipv6/ip6_output.c:141
__ip6_finish_output+0x3cd/0x1010 net/ipv6/ip6_output.c:215
ip6_finish_output net/ipv6/ip6_output.c:226 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x1ca/0x3e0 net/ipv6/ip6_output.c:248
dst_output include/net/dst.h:461 [inline]
ip6_local_out+0xd1/0x4d0 net/ipv6/output_core.c:155
ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1984
ip6_push_pending_frames+0xe0/0x110 net/ipv6/ip6_output.c:2005
icmpv6_push_pending_frames+0x2dc/0x460 net/ipv6/icmp.c:313
icmp6_send+0x1ec9/0x2be0 net/ipv6/icmp.c:634
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
__udp6_lib_rcv+0x2349/0x3040 net/ipv6/udp.c:1167
ip6_protocol_deliver_rcu+0x6f0/0x1520 net/ipv6/ip6_input.c:438
ip6_input_finish+0x1e4/0x4b0 net/ipv6/ip6_input.c:489
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:500
dst_input include/net/dst.h:471 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311
__netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5991
__netif_receive_skb+0x1d/0x160 net/core/dev.c:6104
process_backlog+0x442/0x15e0 net/core/dev.c:6456
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7506
napi_poll net/core/dev.c:7569 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7696
handle_softirqs+0x216/0x8e0 kernel/softirq.c:579
do_softirq kernel/softirq.c:480 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:467
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407
wg_socket_send_skb_to_peer+0x145/0x210 drivers/net/wireguard/socket.c:184
wg_socket_send_buffer_to_peer+0x148/0x1a0 drivers/net/wireguard/socket.c:200
wg_packet_send_handshake_initiation+0x225/0x360 drivers/net/wireguard/send.c:40
wg_packet_handshake_send_worker+0x1c/0x30 drivers/net/wireguard/send.c:51
process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245