rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=42e/1/0x4000000000000002 softirq=11681/11681 fqs=41 
	(t=10501 jiffies g=6277 q=66)
rcu: rcu_preempt kthread starved for 10420 jiffies! g6277 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: 4438 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:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:68 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0xd/0x50 kernel/kcov.c:102
Code: e5 53 48 89 fb e8 13 00 00 00 48 8b 3d 34 e7 cc 07 48 89 de e8 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 <65> 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83
RSP: 0018:ffffc90002677b40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81487326 RBX: ffffea0001b04a80 RCX: ffff8880943de180
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea0001b04a80
RBP: ffffc90002677b68 R08: 000000000003a768 R09: ffffed101404ef2f
R10: ffffed101404ef2f R11: 0000000000000000 R12: ffff8880a72729a0
R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff8880a0277968
 free_thread_stack+0x168/0x590 kernel/fork.c:280
 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:ffffc90002677dc8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: ffff8880943dea14 RBX: 0000000000000cc0 RCX: ffff8880943de180
RDX: 0000000000000000 RSI: ffffffff81be59ca RDI: 0000000000000286
RBP: ffffc90002677e00 R08: ffff8880943de9d8 R09: ffffed101553fbc1
R10: ffffed101553fbc1 R11: 0000000000000000 R12: ffff8880aa9f9a80
R13: ffff8880aa9f9a80 R14: ffff88806c200380 R15: 0000000000000cc0
 getname_flags+0xba/0x640 fs/namei.c:138
 getname+0x19/0x20 fs/namei.c:209
 do_sys_open+0x261/0x560 fs/open.c:1091
 __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: 0033:0x7f21c40a5120
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:00007ffcb251ce98 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000001889fe0 RCX: 00007f21c40a5120
RDX: 00000000000001b6 RSI: 0000000000080241 RDI: 00007ffcb251d380
RBP: 00007ffcb251cf10 R08: 0000000000000004 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000420721 R14: 00007ffcb251cf80 R15: 0000000000000001