rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=0fa/1/0x4000000000000002 softirq=10679/10688 fqs=0 
	(t=10501 jiffies g=6209 q=60)
rcu: rcu_preempt kthread starved for 10502 jiffies! g6209 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 0
CPU: 0 PID: 7786 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:1514 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638
 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+0x12e/0x590 kernel/fork.c:280
Code: bf 00 00 00 00 00 ea ff ff 48 01 c7 be 03 00 00 00 e8 06 a2 60 00 e9 5d 04 00 00 e8 5c 2d 2e 00 48 89 df 31 f6 e8 42 af 6e 00 <43> 80 3c 2e 00 74 08 4c 89 e7 e8 43 a4 69 00 49 8b 1c 24 48 83 c3
RSP: 0018:ffffc90006dc7b18 EFLAGS: 00000292 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: ffffea000280a700 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea000280a700
RBP: ffffc90006dc7b50 R08: dffffc0000000000 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: ffff8880a81f4fa0
R13: dffffc0000000000 R14: 1ffff1101503e9f4 R15: ffff8880a800d568
 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:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:slab_alloc mm/slab.c:3313 [inline]
RIP: 0010:kmem_cache_alloc+0x1a8/0x2e0 mm/slab.c:3484
Code: 8b 7d d0 57 9d 0f 1f 44 00 00 e8 83 b1 ca ff eb 1e e8 1c af ca ff 48 83 3d 7c 10 59 07 00 0f 84 33 01 00 00 48 8b 7d d0 57 9d <0f> 1f 44 00 00 41 0f 18 0e e9 21 00 00 00 89 d8 c1 e8 08 83 e0 01
RSP: 0018:ffffc90006dc7d68 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: ffff8880a3966b54 RBX: 0000000000000cc0 RCX: ffff8880a39662c0
RDX: 0000000000000000 RSI: ffffffff81be59ca RDI: 0000000000000286
RBP: ffffc90006dc7da0 R08: ffff8880a3966b18 R09: ffffed101553fbc1
R10: ffffed101553fbc1 R11: 0000000000000000 R12: ffff8880aa9f9a80
R13: ffff8880aa9f9a80 R14: ffff88806c200800 R15: 0000000000000cc0
 getname_flags+0xba/0x640 fs/namei.c:138
 user_path_at_empty+0x2d/0x50 fs/namei.c:2602
 user_path_at include/linux/namei.h:49 [inline]
 do_utimes+0x1fe/0x2d0 fs/utimes.c:121
 __do_sys_utimensat fs/utimes.c:153 [inline]
 __se_sys_utimensat fs/utimes.c:137 [inline]
 __x64_sys_utimensat+0xfb/0x1e0 fs/utimes.c:137
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7efc31dc7a32
Code: 2b 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 48 85 f6 74 2b 4c 63 d1 48 63 ff b8 18 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 02 f3 c3 48 8b 15 d5 33 2b 00 f7 d8 64 89 02
RSP: 002b:00007fffd8f2dd78 EFLAGS: 00000206 ORIG_RAX: 0000000000000118
RAX: ffffffffffffffda RBX: 000000000141e600 RCX: 00007efc31dc7a32
RDX: 0000000000000000 RSI: 000000000141e600 RDI: ffffffffffffff9c
RBP: 0000000001405250 R08: 0000000000000006 R09: 00007efc31e1c1d0
R10: 0000000000000000 R11: 0000000000000206 R12: 00000000000063b0
R13: 0000000000002b00 R14: 0000000000000000 R15: 0000000000000000