rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=27e/1/0x4000000000000002 softirq=12437/12437 fqs=0 
	(t=10501 jiffies g=6189 q=137)
rcu: rcu_preempt kthread starved for 10502 jiffies! g6189 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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 1
CPU: 1 PID: 8227 Comm: syz-executor.3 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+0x151/0x590 kernel/fork.c:280
Code: 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 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 25 a4 69 00 48 8b 3b be fc ff ff ff e8 28 04 00
RSP: 0018:ffffc900023c7938 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11013f860b1 RBX: ffff88809fc30588 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002232ac0
RBP: ffffc900023c7970 R08: 000000000003a768 R09: ffffed101500667f
R10: ffffed101500667f R11: 0000000000000000 R12: ffff88809fc30620
R13: dffffc0000000000 R14: 1ffff11013f860c4 R15: ffff8880a80333e8
 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:kmalloc_slab+0x4d/0x70 mm/slab_common.c:1139
Code: 81 ff 01 00 40 00 73 40 48 83 ec 04 ff cf 89 3c 24 b8 ff ff ff ff 0f bd 04 24 ff c0 48 83 c4 04 40 f6 c6 11 75 1a 31 f6 89 c0 <48> 69 ce b8 00 00 00 48 8b 84 c1 80 ab e0 88 c3 b8 10 00 00 00 c3
RSP: 0018:ffffc900023c7b80 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff02
RAX: 0000000000000006 RBX: 0000000000000d40 RCX: ffff88809c820000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: ffffc900023c7bc8 R08: ffffffff83564a27 R09: ffffed1012d0d805
R10: ffffed1012d0d805 R11: 0000000000000000 R12: 000000000000002e
R13: 0000000000000023 R14: 0000000000000023 R15: ffffffff83564a53
 kmalloc include/linux/slab.h:561 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 tomoyo_encode2+0x273/0x5a0 security/tomoyo/realpath.c:44
 tomoyo_encode security/tomoyo/realpath.c:79 [inline]
 tomoyo_realpath_from_path+0x769/0x7c0 security/tomoyo/realpath.c:316
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_number_perm+0x166/0x640 security/tomoyo/file.c:723
 tomoyo_file_ioctl+0x23/0x30 security/tomoyo/tomoyo.c:335
 security_file_ioctl+0x6d/0xd0 security/security.c:1409
 ksys_ioctl fs/ioctl.c:747 [inline]
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0xa3/0x120 fs/ioctl.c:754
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a4e7
Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48 f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 0d b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffda8836e18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a4e7
RDX: 00007ffda8836e20 RSI: 0000000000008933 RDI: 0000000000000004
RBP: 00000000004bfaf7 R08: 0000000000000008 R09: 0000000000000008
R10: 000000000000000a R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000006 R14: 0000000000000000 R15: 00007ffda8837050