rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=a06/1/0x4000000000000002 softirq=14752/14752 fqs=7 
	(t=10501 jiffies g=6741 q=209)
rcu: rcu_preempt kthread starved for 10488 jiffies! g6741 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: 8599 Comm: syz-executor.2 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:ffffc90001f17a28 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11013aa2881 RBX: ffff88809d514408 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002533a40
RBP: ffffc90001f17a60 R08: 000000000003a728 R09: fffffbfff124248a
R10: fffffbfff124248a R11: 0000000000000000 R12: ffff88809d5144a0
R13: dffffc0000000000 R14: 1ffff11013aa2894 R15: ffff8880a85a55f8
 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:kmem_cache_free+0xc8/0xf0 mm/slab.c:3695
Code: 77 07 00 74 42 4c 89 f7 57 9d 0f 1f 44 00 00 e8 5e b3 c9 ff eb 19 e8 f7 b0 c9 ff 48 83 3d a7 e1 77 07 00 74 24 4c 89 f7 57 9d <0f> 1f 44 00 00 4c 89 e7 4c 89 fe e8 58 01 00 00 5b 41 5c 41 5e 41
RSP: 0018:ffffc90001f17c70 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02
RAX: ffff8880a81cac54 RBX: ffff88821bc4e540 RCX: ffff8880a81ca3c0
RDX: 0000000000000000 RSI: ffffffff81c2bce9 RDI: 0000000000000286
RBP: ffffc90001f17c90 R08: ffff8880a81cac18 R09: ffffc90001f17a80
R10: 000000000000000d R11: 0000000000000000 R12: ffffffff81c2bce9
R13: ffff8880aa048bc0 R14: 0000000000000286 R15: ffff8880aa048b40
 __d_free fs/dcache.c:271 [inline]
 dentry_free+0xd9/0x150 fs/dcache.c:348
 __dentry_kill+0x4a2/0x5e0 fs/dcache.c:593
 dentry_kill fs/dcache.c:673 [inline]
 dput+0x460/0x6f0 fs/dcache.c:859
 __fput+0x4d3/0x740 fs/file_table.c:293
 ____fput+0x15/0x20 fs/file_table.c:313
 task_work_run+0x17e/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:164 [inline]
 prepare_exit_to_usermode+0x483/0x5b0 arch/x86/entry/common.c:195
 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: 0033:0x45ed03
Code: 48 89 ee 48 89 e7 e8 5c 16 fa ff 31 c0 48 89 e2 be 33 89 00 00 89 df e8 bb c0 ff ff 85 c0 78 17 48 63 fb b8 03 00 00 00 0f 05 <8b> 44 24 10 48 83 c4 38 5b 5d c3 66 90 48 c7 c2 d4 ff ff ff 48 63
RSP: 002b:00007ffc0e88cc80 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000045ed03
RDX: 00007ffc0e88cc80 RSI: 0000000000008933 RDI: 0000000000000004
RBP: 00000000004c04ac R08: 0000000000000000 R09: 000000000000000a
R10: 0000000000000015 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 0000000000000006 R15: 00007ffc0e88cf60