rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=f8e/1/0x4000000000000002 softirq=11082/11082 fqs=40 
	(t=10501 jiffies g=6797 q=124)
rcu: rcu_preempt kthread starved for 10419 jiffies! g6797 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29032    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 1
CPU: 1 PID: 8297 Comm: udevd Not tainted 5.4.0-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+0x18b/0x590 kernel/fork.c:284
Code: ff ff e8 28 04 00 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 09 a0 69 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 eb 9f 69 00 48 8b 1b e9 82 ff ff ff e8 5e 2a 2e
RSP: 0018:ffffc90001ec7a20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11012724141 RBX: ffff888093920a08 RCX: ffff88809e5d43c0
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00028a6040
RBP: ffffc90001ec7a58 R08: 000000000003a728 R09: ffffed1012729f27
R10: ffffed1012729f27 R11: 0000000000000000 R12: ffff888093920aa0
R13: dffffc0000000000 R14: 1ffff11012724154 R15: ffff88809394f928
 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_common kernel/sched/core.c:4236 [inline]
 preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261
 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
 _raw_spin_unlock_irqrestore+0xcc/0xe0 kernel/locking/spinlock.c:191
 debug_object_active_state+0x1e3/0x4a0 lib/debugobjects.c:916
 debug_rcu_head_queue kernel/rcu/rcu.h:177 [inline]
 __call_rcu+0x55/0x670 kernel/rcu/tree.c:2595
 call_rcu+0xb/0x10 kernel/rcu/tree.c:2682
 dentry_free+0xbc/0x150 fs/dcache.c:350
 __dentry_kill+0x4a2/0x5e0 fs/dcache.c:593
 dentry_kill fs/dcache.c:673 [inline]
 dput+0x460/0x6f0 fs/dcache.c:859
 do_renameat2+0x69b/0xff0 fs/namei.c:4627
 __do_sys_rename fs/namei.c:4669 [inline]
 __se_sys_rename fs/namei.c:4667 [inline]
 __x64_sys_rename+0x68/0x80 fs/namei.c:4667
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f64807b3527
Code: 32 00 64 83 38 15 74 07 b8 ff ff ff ff 5b c3 48 89 df e8 1c c1 07 00 85 c0 75 ed 31 c0 eb d3 90 90 90 90 b8 52 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 f8 32 00 31 d2 48 29 c2 64
RSP: 002b:00007fff8a3649e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f64807b3527
RDX: 0000000000e044b0 RSI: 00007fff8a364a20 RDI: 00007fff8a364e20
RBP: 0000000000e03e80 R08: 00007f64811267a0 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000defce0
R13: 0000000000deb250 R14: 00007fff8a364a20 R15: 0000000000000001