rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=e4e/1/0x4000000000000002 softirq=12195/12195 fqs=1 
	(t=10501 jiffies g=6769 q=145)
rcu: rcu_preempt kthread starved for 10500 jiffies! g6769 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: 8395 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:ffffc90001d67728 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11013f4cfa1 RBX: ffff88809fa67d08 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00024df140
RBP: ffffc90001d67760 R08: dffffc0000000000 R09: fffffbfff124248a
R10: fffffbfff124248a R11: 0000000000000000 R12: ffff8880a2c249a0
R13: dffffc0000000000 R14: 1ffff11014584934 R15: ffff88809db8d3f8
 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:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:153 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:208 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0xd/0x90 kernel/kcov.c:274
Code: 14 02 4d 89 44 f2 18 49 ff c1 4d 89 0a c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 4c 8b 04 24 65 48 8b 04 25 c0 1d 02 00 <65> 8b 0d 98 5b 8b 7e f7 c1 00 01 1f 00 75 64 8b 88 80 13 00 00 83
RSP: 0018:ffffc90001d67978 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff02
RAX: ffff88808edf65c0 RBX: 00000000000034e6 RCX: ffff88808edf65c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90001d67998 R08: ffffffff8167648e R09: fffffbfff140cf2e
R10: fffffbfff140cf2e R11: 0000000000000000 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000286 R15: dffffc0000000000
 ktime_get_coarse_real_ts64+0x4a/0xc0 kernel/time/timekeeping.c:2166
 current_time+0x3c/0x260 fs/inode.c:2224
 shmem_get_inode+0x184/0x6e0 mm/shmem.c:2253
 shmem_mknod+0x5c/0x1c0 mm/shmem.c:2884
 shmem_create+0x2b/0x40 mm/shmem.c:2944
 lookup_open fs/namei.c:3241 [inline]
 do_last fs/namei.c:3331 [inline]
 path_openat+0x21d2/0x4240 fs/namei.c:3537
 do_filp_open+0x192/0x3d0 fs/namei.c:3567
 do_sys_open+0x29f/0x560 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x87/0x90 fs/open.c:1110
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fa23c7d4120
Code: 48 8b 15 1b 4d 2b 00 f7 d8 64 89 02 83 c8 ff c3 90 90 90 90 90 90 90 90 90 90 83 3d d5 a4 2b 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 5e 8c 01 00 48 89 04 24
RSP: 002b:00007ffce4b90cd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000aa3d50 RCX: 00007fa23c7d4120
RDX: 00000000000001b6 RSI: 0000000000080241 RDI: 00007ffce4b911c0
RBP: 00007ffce4b90d50 R08: 0000000000000004 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000420721 R14: 00007ffce4b90dc0 R15: 0000000000000001