rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=a12/1/0x4000000000000002 softirq=9881/9881 fqs=8 
	(t=10501 jiffies g=6309 q=405)
rcu: rcu_preempt kthread starved for 10485 jiffies! g6309 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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: 8184 Comm: syz-executor.1 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+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 a4 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 a3 69 00 48 8b 1b e9 82 ff ff ff e8 de 2c 2e
RSP: 0000:ffffc90001fa7d40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff110136c8751 RBX: ffff88809b643a88 RCX: ffff8880a871c1c0
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00029b4380
RBP: ffffc90001fa7d78 R08: 000000000003a768 R09: ffffed10150f9eaf
R10: ffffed10150f9eaf R11: 0000000000000000 R12: ffff88808d014620
R13: dffffc0000000000 R14: 1ffff11011a028c4 R15: ffff8880a87cf568
 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
 schedule+0x181/0x210 kernel/sched/core.c:4155
 exit_to_usermode_loop arch/x86/entry/common.c:150 [inline]
 prepare_exit_to_usermode+0x2d4/0x5b0 arch/x86/entry/common.c:195
 ret_from_intr+0x26/0x36
RIP: 0033:0x40f630
Code: 08 41 bd 00 00 00 80 4a 8d 04 2e 48 3d ff ff ff 7e 0f 87 94 00 00 00 45 31 ff 31 db 31 ed 0f 1f 40 00 48 89 df 89 f0 48 31 f7 <c1> e8 10 83 f6 3d 31 c6 44 8d 4f 04 41 89 f8 8d 1c f6 89 d8 c1 e8
RSP: 002b:00007fff3d0a6050 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 0000000081a2fd3f RBX: 00000000d1fca6f9 RCX: 0000001b33020000
RDX: 0000001b320202ec RSI: ffffffff81a2fd3f RDI: ffffffff505e5bc6
RBP: 00000000000000b3 R08: 000000007a145ab4 R09: 000000007a145ab8
R10: 00007fff3d0a61f0 R11: 0000000000000246 R12: 000000000075bfa8
R13: 0000000080000000 R14: 00007f789e65c008 R15: 0000000000001df1