BUG: Dentry ffff8881985bd220{i=0,n=.index}  still in use (1) [unmount of overlay overlay]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 367 at fs/dcache.c:1597 umount_check+0x179/0x1c0 fs/dcache.c:1588
Modules linked in:
CPU: 1 PID: 367 Comm: syz-executor.1 Not tainted 5.4.112-syzkaller-00262-g4d45d5467a1b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:umount_check+0x179/0x1c0 fs/dcache.c:1588
Code: ff 4c 8b 0b 48 81 c5 20 04 00 00 48 c7 c7 20 f3 e8 84 4c 89 fe 4c 89 f2 4c 89 f9 45 89 e8 31 c0 55 e8 f7 e6 af ff 48 83 c4 08 <0f> 0b e9 fd fe ff ff 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d4 fe ff
RSP: 0018:ffff8881a7a1fc68 EFLAGS: 00010282
RAX: 0000000000000059 RBX: ffffffff85fdede0 RCX: 4b1776106bf9a200
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffff8881ee85d420 R08: ffffffff814e8767 R09: ffffed103ede5e08
R10: ffffed103ede5e08 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8881985bd220
FS:  000000000180c400(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c7d74c000 CR3: 00000001a79c8000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 d_walk+0x2d9/0x540 fs/dcache.c:1307
 do_one_tree fs/dcache.c:1604 [inline]
 shrink_dcache_for_umount+0x8a/0x1a0 fs/dcache.c:1620
 generic_shutdown_super+0x63/0x2a0 fs/super.c:447
 kill_anon_super+0x36/0x60 fs/super.c:1108
 deactivate_locked_super+0xaf/0x100 fs/super.c:335
 deactivate_super+0x1b3/0x270 fs/super.c:366
 cleanup_mnt+0x432/0x4e0 fs/namespace.c:1102
 task_work_run+0x186/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
 prepare_exit_to_usermode+0x2b0/0x310 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4678b7
Code: ff d0 48 89 c7 b8 3c 00 00 00 0f 05 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 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:00007ffe91df7228 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000004678b7
RDX: 00007ffe91df72fb RSI: 0000000000000002 RDI: 00007ffe91df72f0
RBP: 00007ffe91df72f0 R08: 00000000ffffffff R09: 00007ffe91df70c0
R10: 000000000180dc0b R11: 0000000000000246 R12: 00000000004bebb2
R13: 00007ffe91df83c0 R14: 000000000180db00 R15: 00007ffe91df8400
---[ end trace f8b7d7ab4894f6bb ]---
BUG: Dentry ffff8881985bd220{i=0,n=.index}  still in use (1) [unmount of overlay overlay]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 367 at fs/dcache.c:1597 umount_check+0x179/0x1c0 fs/dcache.c:1588
Modules linked in:
CPU: 1 PID: 367 Comm: syz-executor.1 Tainted: G        W         5.4.112-syzkaller-00262-g4d45d5467a1b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:umount_check+0x179/0x1c0 fs/dcache.c:1588
Code: ff 4c 8b 0b 48 81 c5 20 04 00 00 48 c7 c7 20 f3 e8 84 4c 89 fe 4c 89 f2 4c 89 f9 45 89 e8 31 c0 55 e8 f7 e6 af ff 48 83 c4 08 <0f> 0b e9 fd fe ff ff 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d4 fe ff
RSP: 0018:ffff8881a7a1fc68 EFLAGS: 00010282
RAX: 0000000000000059 RBX: ffffffff85fdede0 RCX: 4b1776106bf9a200
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000
RBP: ffff8881ee85d420 R08: ffffffff814e8767 R09: ffffed103ede5e08
R10: ffffed103ede5e08 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8881985bd220
FS:  000000000180c400(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c7d74c000 CR3: 00000001a79c8000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 d_walk+0x2d9/0x540 fs/dcache.c:1307
 do_one_tree fs/dcache.c:1604 [inline]
 shrink_dcache_for_umount+0x8a/0x1a0 fs/dcache.c:1620
 generic_shutdown_super+0x63/0x2a0 fs/super.c:447
 kill_anon_super+0x36/0x60 fs/super.c:1108
 deactivate_locked_super+0xaf/0x100 fs/super.c:335
 deactivate_super+0x1b3/0x270 fs/super.c:366
 cleanup_mnt+0x432/0x4e0 fs/namespace.c:1102
 task_work_run+0x186/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
 prepare_exit_to_usermode+0x2b0/0x310 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4678b7
Code: ff d0 48 89 c7 b8 3c 00 00 00 0f 05 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 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:00007ffe91df7228 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000004678b7
RDX: 00007ffe91df72fb RSI: 0000000000000002 RDI: 00007ffe91df72f0
RBP: 00007ffe91df72f0 R08: 00000000ffffffff R09: 00007ffe91df70c0
R10: 000000000180dc0b R11: 0000000000000246 R12: 00000000004bebb2
R13: 00007ffe91df83c0 R14: 000000000180db00 R15: 00007ffe91df8400
---[ end trace f8b7d7ab4894f6bc ]---
VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds.  Have a nice day...