BUG: Dentry ffff88810db16990{i=0,n=.index}  still in use (1) [unmount of overlay overlay]
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WARNING: CPU: 1 PID: 32243 at fs/dcache.c:1616 umount_check+0x18d/0x1d0 fs/dcache.c:1607
Modules linked in:
CPU: 1 PID: 32243 Comm: syz-executor.1 Not tainted 5.10.76-syzkaller-01178-g4944ec82ebb9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:umount_check+0x18d/0x1d0 fs/dcache.c:1607
Code: 8b 0b 49 81 c6 f8 03 00 00 48 c7 c7 40 44 2e 85 4c 89 e6 48 8b 55 d0 4c 89 e1 45 89 f8 31 c0 41 56 e8 5e d9 9e ff 48 83 c4 08 <0f> 0b e9 f1 fe ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c c9 fe ff
RSP: 0018:ffffc90000c87c90 EFLAGS: 00010296
RAX: 0000000000000059 RBX: ffffffff866d06a0 RCX: 9145128b0748de00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffffc90000c87cc0 R08: ffffffff81545288 R09: ffffed103ee295d8
R10: ffffed103ee295d8 R11: 0000000000000000 R12: ffff88810db16990
R13: dffffc0000000000 R14: ffff88816d7813f8 R15: 0000000000000001
FS:  00005555566ec400(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556705bb8 CR3: 0000000111599000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 d_walk+0x309/0x540 fs/dcache.c:1326
 do_one_tree fs/dcache.c:1623 [inline]
 shrink_dcache_for_umount+0x8e/0x1b0 fs/dcache.c:1639
 generic_shutdown_super+0x66/0x2c0 fs/super.c:447
 kill_anon_super+0x3c/0x70 fs/super.c:1108
 deactivate_locked_super+0xb0/0x100 fs/super.c:335
 deactivate_super+0xa5/0xd0 fs/super.c:366
 cleanup_mnt+0x45f/0x510 fs/namespace.c:1118
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1125
 task_work_run+0x147/0x1b0 kernel/task_work.c:154
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0xc3/0xe0 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x24/0x40 kernel/entry/common.c:266
 do_syscall_64+0x3d/0x70 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fb25bffef57
Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc14dcbb78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fb25bffef57
RDX: 00007ffc14dcbc49 RSI: 000000000000000a RDI: 00007ffc14dcbc40
RBP: 00007ffc14dcbc40 R08: 00000000ffffffff R09: 00007ffc14dcba10
R10: 00005555566edc33 R11: 0000000000000246 R12: 00007fb25c0570bd
R13: 00007ffc14dccd00 R14: 00005555566edb00 R15: 00007ffc14dccd40
---[ end trace 83dbf4ffaf0a28e1 ]---
VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds.  Have a nice day...