rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=6e94/1/0x4000000000000000 softirq=24841/24878 fqs=0
rcu: (detected by 0, t=10502 jiffies, g=31861, q=885 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 54 Comm: kworker/u8:4 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
RIP: 0010:debug_spin_unlock kernel/locking/spinlock_debug.c:103 [inline]
RIP: 0010:do_raw_spin_unlock+0xa1/0x210 kernel/locking/spinlock_debug.c:141
Code: 7c 25 00 00 74 08 4c 89 f7 e8 3b 32 91 00 65 48 8b 05 7b e5 c9 11 49 39 06 0f 85 b2 00 00 00 4c 8d 7b 08 4c 89 fd 48 c1 ed 03 <42> 0f b6 44 25 00 84 c0 0f 85 16 01 00 00 41 8b 07 65 8b 0d 7b e5
RSP: 0000:ffffc90000a08cd0 EFLAGS: 00000802
RAX: ffff88801c310000 RBX: ffffffff9aa01458 RCX: ffffffff81a2ca4d
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff9aa01458
RBP: 1ffffffff354028c R08: ffffffff9aa0145b R09: 1ffffffff354028b
R10: dffffc0000000000 R11: fffffbfff354028c R12: dffffc0000000000
R13: 1ffffffff354028d R14: ffffffff9aa01468 R15: ffffffff9aa01460
FS: 0000000000000000(0000) GS:ffff888125055000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f7011ac0 CR3: 0000000022f96000 CR4: 00000000003526f0
Call Trace:
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:177 [inline]
_raw_spin_unlock_irqrestore+0x23/0x80 kernel/locking/spinlock.c:198
debug_object_activate+0x2ec/0x420 lib/debugobjects.c:891
debug_hrtimer_activate kernel/time/hrtimer.c:485 [inline]
debug_activate kernel/time/hrtimer.c:528 [inline]
enqueue_hrtimer+0xa9/0x2c0 kernel/time/hrtimer.c:1109
__run_hrtimer kernel/time/hrtimer.c:2048 [inline]
__hrtimer_run_queues+0x4ce/0xa10 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 61 3f 2d 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 4b 8a ca 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 98 eb b8
RSP: 0000:ffffc90000bf75e8 EFLAGS: 00000286
RAX: 6ae60dba54722400 RBX: 0000000000000000 RCX: 0000000080000401
RDX: 00000000137df13a RSI: ffffffff8e4b03b4 RDI: ffffffff8c4bda80
RBP: ffffffff8a7cb02d R08: ffffffff8a7cb02d R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000002
R13: ffffffff8eb59c60 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
ip6_dst_mtu_maybe_forward include/net/ip6_route.h:378 [inline]
ip6_mtu+0x9a/0x490 net/ipv6/route.c:3290
__ip6_finish_output net/ipv6/ip6_output.c:200 [inline]
ip6_finish_output+0x134/0x480 net/ipv6/ip6_output.c:219
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x337/0x540 net/ipv6/ip6_output.c:246
ip6tunnel_xmit include/net/ip6_tunnel.h:174 [inline]
udp_tunnel6_xmit_skb+0x6c1/0xd40 net/ipv6/ip6_udp_tunnel.c:112
send6+0x5ce/0x920 drivers/net/wireguard/socket.c:151
wg_socket_send_skb_to_peer+0x111/0x1d0 drivers/net/wireguard/socket.c:177
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x204/0x370 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: rcu_preempt kthread starved for 10502 jiffies! g31861 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27656 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5288 Comm: dhcpcd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x10b0/0x14b0 kernel/smp.c:892
Code: c0 75 73 41 8b 1e 89 de 83 e6 01 31 ff e8 d8 22 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 84 1e 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 69 1e 0c
RSP: 0018:ffffc900034f7580 EFLAGS: 00000293
RAX: ffffffff81ba5317 RBX: dffffc0000000000 RCX: ffff88802c938000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900034f76a8 R08: ffffffff905783f7 R09: 1ffffffff20af07e
R10: dffffc0000000000 R11: fffffbfff20af07f R12: 1ffff110170e81d1
R13: ffff8880b863c448 R14: ffff8880b8740e88 R15: 0000000000000001
FS: 00007f8efb232780(0000) GS:ffff888124f55000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f7492028 CR3: 0000000034880000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
__flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x5c4/0x1090 arch/x86/mm/tlb.c:1451
dup_mmap+0x1786/0x1d90 mm/mmap.c:1905
dup_mm kernel/fork.c:1543 [inline]
copy_mm+0x11a/0x480 kernel/fork.c:1595
copy_process+0x1e3e/0x4390 kernel/fork.c:2289
kernel_clone+0x2d7/0x940 kernel/fork.c:2748
__do_sys_clone kernel/fork.c:2889 [inline]
__se_sys_clone kernel/fork.c:2873 [inline]
__x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8efb306636
Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffff41c2240 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffff41c2248 RCX: 00007f8efb306636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffff41e2790 R08: 0000000000000000 R09: 0000000000000001
R10: 00007f8efb232a50 R11: 0000000000000246 R12: 00007ffff41c2380
R13: 0000000000000000 R14: 0000000000000000 R15: 000055a7032efac0