rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=ad2/1/0x4000000000000002 softirq=10247/10248 fqs=3 
	(t=10501 jiffies g=8305 q=335)
rcu: rcu_preempt kthread starved for 10496 jiffies! g8305 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29096    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3383 [inline]
 __schedule+0x8ae/0x19c0 kernel/sched/core.c:4099
 schedule+0xc3/0x2b0 kernel/sched/core.c:4173
 schedule_timeout+0x2bd/0x710 kernel/time/timer.c:1896
 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline]
 rcu_gp_kthread+0x9da/0x1a40 kernel/rcu/tree.c:1836
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 8158 Comm: syz-executor.1 Not tainted 5.6.0-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+0x12d/0x187 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold.7+0x4b/0x84 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x18b/0x1b7 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x1a1/0x1ee kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
 rcu_pending kernel/rcu/tree.c:3225 [inline]
 rcu_sched_clock_irq.cold.87+0x3c7/0xc50 kernel/rcu/tree.c:2296
 update_process_times+0x23/0x50 kernel/time/timer.c:1727
 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:176
 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1320
 __run_hrtimer kernel/time/hrtimer.c:1519 [inline]
 __hrtimer_run_queues+0x36d/0xc30 kernel/time/hrtimer.c:1583
 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1645
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
 smp_apic_timer_interrupt+0x163/0x5f0 arch/x86/kernel/apic/apic.c:1138
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__might_fault+0xa/0x1b0 mm/memory.c:4637
Code: 00 74 0c 48 89 c7 48 89 f8 0f 1f 40 00 c9 c3 0f 0b 48 89 45 f8 e8 a6 72 0e 00 48 8b 45 f8 eb d9 48 b8 00 00 00 00 00 fc ff df <55> 48 89 e5 41 54 49 89 fc 53 65 48 8b 1c 25 00 1f 02 00 48 8d bb
RSP: 0000:ffffc9000725fd38 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 0000000000000030 RCX: 0000000000000003
RDX: 0000000000000030 RSI: 000000000000001a RDI: ffffffff87ec6320
RBP: ffffc9000725fd60 R08: 0000000000000000 R09: 00007fe8f322e4b8
R10: fffffbfff141bf45 R11: ffffffff8a0dfa2f R12: 00007fe8f322e5f0
R13: ffffc9000725fe58 R14: ffffc9000725ff58 R15: ffff88808c91a480
 copy_to_user include/linux/uaccess.h:152 [inline]
 copy_siginfo_to_user+0x13/0x40 kernel/signal.c:3191
 __setup_rt_frame arch/x86/kernel/signal.c:468 [inline]
 setup_rt_frame arch/x86/kernel/signal.c:704 [inline]
 handle_signal arch/x86/kernel/signal.c:748 [inline]
 do_signal+0x9cf/0x1710 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x244/0x2f0 arch/x86/entry/common.c:195
 ret_from_intr+0x26/0x36
RIP: 0033:0x4057e9
Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 4a d3 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 e7 ee 00 00 89 44 24 34 64 f0
RSP: 002b:00007fe8f322ea70 EFLAGS: 00010202
RAX: 000000002442c108 RBX: 0000000000000007 RCX: 0000000000414717
RDX: f287260892e57253 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 00007fe8f322ea70 R09: 000000000075bf20
R10: 0000000000000000 R11: 0000000000000000 R12: 00007fe8f322f6d4
R13: 00000000004cae58 R14: 00000000004e4478 R15: 00000000ffffffff