rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): (detected by 0, t=10502 jiffies, g=88193, q=525) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295010903-4295000401), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g88193 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:28864 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4681 [inline] __schedule+0x93a/0x26f0 kernel/sched/core.c:5938 schedule+0xd3/0x270 kernel/sched/core.c:6017 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline] rcu_gp_kthread+0xd34/0x1980 kernel/rcu/tree.c:2169 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 9764 Comm: kworker/0:6 Not tainted 5.14.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: wg-crypt-wg2 wg_packet_tx_worker Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1d1/0x1d6 kernel/rcu/tree_stall.h:479 print_other_cpu_stall kernel/rcu/tree_stall.h:584 [inline] check_cpu_stall kernel/rcu/tree_stall.h:709 [inline] rcu_pending kernel/rcu/tree.c:3922 [inline] rcu_sched_clock_irq+0x2001/0x20c0 kernel/rcu/tree.c:2641 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1537 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:90 [inline] RIP: 0010:kvm_wait arch/x86/kernel/kvm.c:888 [inline] RIP: 0010:kvm_wait+0xaf/0xf0 arch/x86/kernel/kvm.c:871 Code: 10 c3 c3 89 74 24 0c 48 89 3c 24 e8 3b a5 48 00 8b 74 24 0c 48 8b 3c 24 eb 82 e8 4c aa 48 00 eb 07 0f 00 2d d3 c5 55 08 fb f4 9b eb 07 0f 00 2d c6 c5 55 08 f4 eb c5 89 74 24 0c 48 89 3c 24 RSP: 0018:ffffc900163ff5f8 EFLAGS: 00000206 RAX: 000000000001c8fc RBX: 0000000000000000 RCX: 1ffffffff1fa4e22 RDX: 0000000000000000 RSI: 0000000000000803 RDI: 0000000000000000 RBP: ffff88802dd780f0 R08: 0000000000000001 R09: ffffffff8fcd59bf R10: 0000000000000001 R11: 000000000000000c R12: 0000000000000000 R13: ffffed1005baf01e R14: 0000000000000001 R15: ffff8880b9c52880 pv_wait arch/x86/include/asm/paravirt.h:597 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x8b8/0xb40 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:113 spin_lock include/linux/spinlock.h:354 [inline] __dev_xmit_skb net/core/dev.c:3913 [inline] __dev_queue_xmit+0x1d1f/0x3620 net/core/dev.c:4253 neigh_hh_output include/net/neighbour.h:499 [inline] neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0xef0/0x2220 net/ipv4/ip_output.c:230 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x396/0x640 net/ipv4/ip_output.c:290 ip_finish_output+0x32/0x200 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x196/0x310 net/ipv4/ip_output.c:432 dst_output include/net/dst.h:448 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126 iptunnel_xmit+0x5a3/0x9c0 net/ipv4/ip_tunnel_core.c:82 send4+0x421/0xe40 drivers/net/wireguard/socket.c:85 wg_socket_send_skb_to_peer+0x192/0x220 drivers/net/wireguard/socket.c:174 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline] wg_packet_tx_worker+0x1a7/0x720 drivers/net/wireguard/send.c:276 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 10 c3 adc %al,%bl 2: c3 retq 3: 89 74 24 0c mov %esi,0xc(%rsp) 7: 48 89 3c 24 mov %rdi,(%rsp) b: e8 3b a5 48 00 callq 0x48a54b 10: 8b 74 24 0c mov 0xc(%rsp),%esi 14: 48 8b 3c 24 mov (%rsp),%rdi 18: eb 82 jmp 0xffffff9c 1a: e8 4c aa 48 00 callq 0x48aa6b 1f: eb 07 jmp 0x28 21: 0f 00 2d d3 c5 55 08 verw 0x855c5d3(%rip) # 0x855c5fb 28: fb sti 29: f4 hlt 2a: eb 9b jmp 0xffffffc7 <-- trapping instruction 2c: eb 07 jmp 0x35 2e: 0f 00 2d c6 c5 55 08 verw 0x855c5c6(%rip) # 0x855c5fb 35: f4 hlt 36: eb c5 jmp 0xfffffffd 38: 89 74 24 0c mov %esi,0xc(%rsp) 3c: 48 89 3c 24 mov %rdi,(%rsp)