syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=8f6/1/0x4000000000000002 softirq=35842/35842 fqs=3 
rcu: 	 (t=10500 jiffies g=44077 q=50)
rcu: rcu_preempt kthread starved for 10494 jiffies! g44077 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    21560    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2825 [inline]
 __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
 schedule+0xfe/0x460 kernel/sched/core.c:3517
 schedule_timeout+0x140/0x260 kernel/time/timer.c:1804
 rcu_gp_kthread+0x9d9/0x2310 kernel/rcu/tree.c:2194
 kthread+0x35a/0x420 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
NMI backtrace for cpu 1
CPU: 1 PID: 17344 Comm: syz-executor3 Not tainted 4.19.0-rc3+ #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:162 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340
 print_cpu_stall.cold.78+0x2d3/0x524 kernel/rcu/tree.c:1478
 check_cpu_stall kernel/rcu/tree.c:1550 [inline]
 __rcu_pending kernel/rcu/tree.c:3276 [inline]
 rcu_pending kernel/rcu/tree.c:3319 [inline]
 rcu_check_callbacks+0xfd9/0x1990 kernel/rcu/tree.c:2665
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x41c/0x10d0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x313/0x780 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1029 [inline]
 smp_apic_timer_interrupt+0x1a1/0x760 arch/x86/kernel/apic/apic.c:1054
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
 </IRQ>
RIP: 0010:arch_local_irq_enable arch/x86/include/asm/paravirt.h:798 [inline]
RIP: 0010:walk_shadow_page_lockless_end arch/x86/kvm/mmu.c:906 [inline]
RIP: 0010:fast_page_fault+0x6e3/0x1370 arch/x86/kvm/mmu.c:3388
Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 a1 0a 00 00 48 83 3d 17 5a 40 08 00 0f 84 f7 08 00 00 e8 d4 00 6d 00 fb 66 0f 1f 44 00 00 <e9> 95 fd ff ff 4c 89 bd 60 fe ff ff e8 bc 00 6d 00 48 8b 85 30 fe
RSP: 0018:ffff8801932beaa8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc9000365c000
RDX: 0000000000040000 RSI: ffffffff8111cfec RDI: ffffffff895229f8
RBP: ffff8801932bec98 R08: ffff8801c308ac20 R09: 0000000000000006
R10: 0000000000000000 R11: ffff8801c308a380 R12: 0000000000000000
R13: 1ffff10032657d6e R14: 0000000000000000 R15: 0000000000000002
 tdp_page_fault+0x37f/0xbe0 arch/x86/kvm/mmu.c:4057
 kvm_mmu_page_fault+0x226/0x1b30 arch/x86/kvm/mmu.c:5233
 handle_ept_violation+0x29e/0x6a0 arch/x86/kvm/vmx.c:7679
 vmx_handle_exit+0x2f7/0x17e0 arch/x86/kvm/vmx.c:10115
 vcpu_enter_guest+0x14a9/0x62e0 arch/x86/kvm/x86.c:7648
 vcpu_run arch/x86/kvm/x86.c:7711 [inline]
 kvm_arch_vcpu_ioctl_run+0x375/0x16e0 arch/x86/kvm/x86.c:7888
 kvm_vcpu_ioctl+0x72b/0x1150 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457099
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2e48dbcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2e48dbd6d4 RCX: 0000000000457099
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cf730 R14: 00000000004c59b9 R15: 0000000000000000
bpfilter: read fail -512