rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=baa/1/0x4000000000000002 softirq=11529/11529 fqs=0 
	(t=10501 jiffies g=6449 q=144)
rcu: rcu_preempt kthread starved for 10502 jiffies! g6449 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29032    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: 7889 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:free_thread_stack+0x195/0x590 kernel/fork.c:284
Code: 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 00 43 80 3c 2e 00 75 18 eb 1e
RSP: 0018:ffffc90006ea77b8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11013d8d4b1 RBX: ffff88809ec6a588 RCX: ffff88808f800600
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea0002434cc0
RBP: ffffc90006ea77f0 R08: 000000000003a768 R09: ffffed10150aba97
R10: ffffed10150aba97 R11: 0000000000000000 R12: ffff88809ec6a620
R13: dffffc0000000000 R14: 1ffff11013d8d4c4 R15: ffff8880a855d4a8
 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:__rcu_read_unlock+0xc4/0x680 kernel/rcu/tree_plugin.h:392
Code: eb 23 44 8d 7b ff 43 8a 44 35 00 84 c0 0f 85 c6 04 00 00 45 89 3c 24 81 c3 fd ff ff 3f 81 fb fd ff ff 3f 76 0f 48 83 c4 28 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 0f 0b eb ed 44 89 e1 80 e1 07 80 c1
RSP: 0018:ffffc90006ea7a08 EFLAGS: 00000296 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81c95100 RBX: dffffc0000000000 RCX: ffff88808f800600
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880aec37e60
RBP: ffffc90006ea7a28 R08: dffffc0000000000 R09: ffffed1015d86fcd
R10: ffffed1015d86fcd R11: 0000000000000000 R12: ffff88808f800978
R13: 1ffff11011f0012f R14: dffffc0000000000 R15: 0000000000000001
 rcu_read_unlock include/linux/rcupdate.h:670 [inline]
 prepend_path+0x735/0xa70 fs/d_path.c:134
 d_absolute_path+0xde/0x190 fs/d_path.c:201
 tomoyo_get_absolute_path security/tomoyo/realpath.c:100 [inline]
 tomoyo_realpath_from_path+0x46b/0x7c0 security/tomoyo/realpath.c:304
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x192/0x850 security/tomoyo/file.c:822
 tomoyo_inode_getattr+0x1c/0x20 security/tomoyo/tomoyo.c:129
 security_inode_getattr+0xd5/0x150 security/security.c:1222
 vfs_getattr+0x2a/0x6d0 fs/stat.c:115
 vfs_statx fs/stat.c:191 [inline]
 vfs_stat include/linux/fs.h:3249 [inline]
 __do_sys_newstat fs/stat.c:341 [inline]
 __se_sys_newstat+0x9a/0x150 fs/stat.c:337
 __x64_sys_newstat+0x5b/0x70 fs/stat.c:337
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f03e484cc65
Code: 00 00 00 e8 5d 01 00 00 48 83 c4 18 c3 90 90 90 90 90 90 90 90 83 ff 01 48 89 f0 77 18 48 89 c7 48 89 d6 b8 04 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 17 f3 c3 90 48 8b 05 a1 51 2b 00 64 c7 00 16
RSP: 002b:00007ffcf9b72938 EFLAGS: 00000246 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 00007ffcf9b729d0 RCX: 00007f03e484cc65
RDX: 00007ffcf9b72940 RSI: 00007ffcf9b72940 RDI: 00007ffcf9b729d0
RBP: 00000000016e32b0 R08: 00007ffcf9b729e0 R09: 00007f03e48a2de0
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000016e1250
R13: 0000000000000000 R14: 00000000016e1250 R15: 000000000000000b