rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=c0e/1/0x4000000000000002 softirq=13173/13173 fqs=9 
	(t=10500 jiffies g=6753 q=653)
rcu: rcu_preempt kthread starved for 10481 jiffies! g6753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29104    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 8524 Comm: udevd Not tainted 5.5.0-rc5-syzkaller #0
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+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:free_thread_stack+0x151/0x590 kernel/fork.c:280
Code: 31 f6 e8 02 8d 6f 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 73 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 55 94 6a 00 48 8b 3b be fc ff ff ff e8 28 04 00
RSP: 0018:ffffc90001d67c18 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11011e01251 RBX: ffff88808f009288 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002646f00
RBP: ffffc90001d67c50 R08: 000000000003a728 R09: ffffed1012f536b9
R10: ffffed1012f536b9 R11: 0000000000000000 R12: ffff88808f009320
R13: dffffc0000000000 R14: 1ffff11011e01264 R15: ffff888097a9b5b8
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:exit_to_usermode_loop arch/x86/entry/common.c:149 [inline]
RIP: 0010:prepare_exit_to_usermode+0x2ae/0x5b0 arch/x86/entry/common.c:195
Code: 45 a0 42 80 3c 28 00 74 0c 48 c7 c7 78 95 2a 89 e8 b7 b5 b2 00 48 83 3d 57 24 2a 08 00 0f 84 fa 02 00 00 fb 66 0f 1f 44 00 00 <44> 89 e6 83 e6 08 31 ff e8 e5 50 76 00 44 89 e0 83 e0 08 75 07 e8
RSP: 0018:ffffc90001d67e60 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02
RAX: 1ffffffff12552af RBX: ffff8880919c6d30 RCX: ffff8880919c65c0
RDX: 0000000000000000 RSI: ffffffff81007543 RDI: ffff8880919c6e04
RBP: ffffc90001d67ec0 R08: ffff8880919c6e18 R09: ffffed1012338cb9
R10: ffffed1012338cb9 R11: 0000000000000000 R12: 000000000000000a
R13: dffffc0000000000 R14: 1ffff11012338cb8 R15: ffff8880919c65c0
 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278
 do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f32a3a632b0
Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24
RSP: 002b:00007ffe39f1e988 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000e2ae80 RCX: 00007f32a3a632b0
RDX: 0000000000000018 RSI: 00007f32a4362000 RDI: 0000000000000005
RBP: 0000000000000000 R08: 00007f32a435b7a0 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000e12250 R14: 00007ffe39f1ea00 R15: 0000000000000001