rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=5a6/1/0x4000000000000002 softirq=11975/11977 fqs=2756 
	(t=10501 jiffies g=6725 q=697)
rcu: rcu_preempt kthread starved for 4987 jiffies! g6725 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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 1
CPU: 1 PID: 8345 Comm: syz-executor.0 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:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:98
Code: 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 53 48 89 fb e8 13 00 00 00 48 8b 3d 34 e7 cc 07 48 89 de e8 64 02 3b 00 5b 5d c3 cc <48> 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2
RSP: 0018:ffffc900023a7760 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffffd400046fadf RBX: 0000000000000000 RCX: ffff8880a7ab6180
RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea000237d6c0
RBP: ffffc900023a7788 R08: 000000000003a768 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: dffffc0000000000
R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff8880a2e815a8
 free_thread_stack+0x168/0x590 kernel/fork.c:280
 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:__ext4_check_dir_entry+0x44/0x380 fs/ext4/dir.c:73
Code: 4d a8 49 89 d4 89 75 cc 48 89 7d c0 49 bf 00 00 00 00 00 fc ff df e8 6b 6d 7d ff 49 8d 5e 04 48 89 d8 48 c1 e8 03 42 8a 04 38 <84> c0 0f 85 7e 02 00 00 44 0f b7 2b bf 0c 00 00 00 44 89 ee e8 53
RSP: 0018:ffffc900023a79e8 EFLAGS: 00000a07 ORIG_RAX: ffffffffffffff13
RAX: 1ffff1100df4ce00 RBX: ffff88806fa67004 RCX: ffff8880a7ab6180
RDX: 0000000000000000 RSI: 000000000000078c RDI: ffffffff88c06fb8
RBP: ffffc900023a7a40 R08: ffff88806fa67000 R09: ffff888092538690
R10: 0000000000001000 R11: 0000000000000000 R12: ffff88808ecba608
R13: 0000000000000000 R14: ffff88806fa67000 R15: dffffc0000000000
 ext4_find_dest_de fs/ext4/namei.c:1931 [inline]
 add_dirent_to_buf+0x4d9/0xc50 fs/ext4/namei.c:1995
 ext4_add_entry+0x24d6/0x3e70 fs/ext4/namei.c:2225
 ext4_add_nondir+0x97/0x260 fs/ext4/namei.c:2561
 ext4_symlink+0x919/0xf60 fs/ext4/namei.c:3344
 vfs_symlink+0x36f/0x4f0 fs/namei.c:4123
 do_symlinkat+0x187/0x3f0 fs/namei.c:4150
 __do_sys_symlink fs/namei.c:4169 [inline]
 __se_sys_symlink fs/namei.c:4167 [inline]
 __x64_sys_symlink+0x60/0x70 fs/namei.c:4167
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a3a7
Code: 0f 1f 00 b8 5c 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 6d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc8c26edf8 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045a3a7
RDX: 00007ffc8c26ee97 RSI: 00000000004c00d3 RDI: 00007ffc8c26ee80
RBP: 0000000000000000 R08: 0000000000000220 R09: 0000000000000017
R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000000001
R13: 00007ffc8c26ee30 R14: 0000000000000000 R15: 00007ffc8c26ee40