BUG: Dentry still in use [unmount of vfat loop4]

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
android-54	BUG: Dentry still in use [unmount of vfat loop4] (2)				1	945d	945d	0/2	auto-closed as invalid on 2022/01/28 05:41
android-54	BUG: Dentry still in use [unmount of ramfs ramfs]	C			476	817d	1140d	0/2	auto-obsoleted due to no activity on 2023/04/21 02:49

BUG: Dentry ffff888179d94000{i=0,n=.index}  still in use (1) [unmount of vfat loop4]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 11764 at fs/dcache.c:1597 umount_check+0x179/0x1c0 fs/dcache.c:1588
Modules linked in:
CPU: 1 PID: 11764 Comm: syz-executor.4 Tainted: G        W         5.4.121-syzkaller-00749-gc6775ce1621b #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 e0 01 e9 84 4c 89 fe 4c 89 f2 4c 89 f9 45 89 e8 31 c0 55 e8 b7 a9 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:ffff8881a7c87c58 EFLAGS: 00010282
RAX: 0000000000000054 RBX: ffffffff85fc59a0 RCX: 32ca984f89eb0000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffff88819d296420 R08: ffffffff814e8397 R09: ffffed103ede5e08
R10: ffffed103ede5e08 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffff888179d94000
FS:  00000000018f2400(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000001 CR3: 00000001a2a65000 CR4: 00000000001426e0
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_block_super+0x79/0xd0 fs/super.c:1444
 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: 0033:0x467a37
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:00007ffcfbf96718 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000467a37
RDX: 00007ffcfbf967ec RSI: 0000000000000002 RDI: 00007ffcfbf967e0
RBP: 00007ffcfbf967e0 R08: 00000000ffffffff R09: 00007ffcfbf965b0
R10: 00000000018f3bd3 R11: 0000000000000246 R12: 00000000004bee70
R13: 00007ffcfbf978b0 R14: 00000000018f3b00 R15: 00007ffcfbf978f0
---[ end trace 85c3e3ebd4e8ebfe ]---
VFS: Busy inodes after unmount of loop4. Self-destruct in 5 seconds.  Have a nice day...

Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Manager	Title
2021/05/25 07:22	android12-5.4	c6775ce1621b	3c7fef33	.config	console log	report	info	ci2-android-5-4-kasan	BUG: Dentry still in use [unmount of vfat loop4]
2021/03/24 06:12	android12-5.4	c50ff8e5608b	e613994b	.config	console log	report	info	ci2-android-5-4-kasan	BUG: Dentry still in use [unmount of vfat loop4]
2020/12/23 21:38	android12-5.4	8657d5d6282f	c2c1d1dd	.config	console log	report	info	ci2-android-5-4-kasan