BUG: Dentry still in use in unmount

Status: upstream: reported C repro on 2025/01/06 14:20
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+d7dfbc1b53951d7719af@syzkaller.appspotmail.com
First crash: 578d, last: 99d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/01/07 linux-6.1.y (ToT) 7dc732d24ff7 C [report] BUG: Dentry still in use in unmount
2025/01/07 upstream (ToT) fbfd64d25c7a C Didn't crash
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: Dentry still in use in unmount f2fs -1 syz, C done 58 965d 1442d 25/29 fixed on 2024/01/20 21:18
android-5-10 BUG: Dentry still in use [unmount of ext4 loop0] -1 syz, C error 63 1710d 1748d 0/2 closed as dup on 2021/10/28 13:08
upstream BUG: Dentry still in use in unmount (3) ocfs2 -1 syz, C 7 385d 498d 0/29 auto-obsoleted due to no activity on 2025/10/26 01:27
upstream BUG: Dentry still in use in unmount (2) fs -1 1 603d 599d 0/29 auto-obsoleted due to no activity on 2025/03/12 01:48
android-5-10 BUG: Dentry still in use in unmount -1 syz, C done 1184 1626d 1638d 2/2 fixed on 2022/02/25 03:20
linux-6.6 BUG: Dentry still in use in unmount origin:lts-only -1 syz, C error 4 295d 304d 0/2 upstream: reported C repro on 2025/10/06 19:49
android-54 BUG: Dentry still in use [unmount of ramfs ramfs] -1 syz, C 476 1645d 1967d 0/2 auto-obsoleted due to no activity on 2023/04/21 02:49
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/01/17 11:41 3h43m fix candidate upstream OK (0) job log

Sample crash report:
BUG: Dentry 000000009bfb5dcf{i=42a2,n=bus}  still in use (1) [unmount of ocfs2 loop0]
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4428 at fs/dcache.c:1681 umount_check+0x180/0x1bc fs/dcache.c:1672
Modules linked in:
CPU: 0 PID: 4428 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : umount_check+0x180/0x1bc fs/dcache.c:1672
lr : umount_check+0x180/0x1bc fs/dcache.c:1672
sp : ffff800021237870
x29: ffff800021237870 x28: ffff0000eae555a8 x27: ffff0000eae55cf0
x26: ffff0000eae55490 x25: ffff0000eae55be8 x24: ffff0000dad50000
x23: dfff800000000000 x22: ffff8000158c9680 x21: 0000000000000001
x20: 00000000000042a2 x19: ffff0000eae55be8 x18: ffff800011b9bf60
x17: 6e755b2029312820 x16: ffff8000082d92bc x15: 0000000000000000
x14: 0000000000000001 x13: 1ffff00004246e74 x12: 0000000000ff0100
x11: ff00800008311668 x10: 0000000000000000 x9 : 9b207ee196e66f00
x8 : 9b207ee196e66f00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021237338 x4 : ffff800015304cc0 x3 : ffff80000a891730
x2 : ffff00019f531d10 x1 : 0000000100000002 x0 : 0000000000000055
Call trace:
 umount_check+0x180/0x1bc fs/dcache.c:1672
 d_walk+0x1b8/0x654 fs/dcache.c:1391
 do_one_tree+0x40/0xf0 fs/dcache.c:1688
 shrink_dcache_for_umount+0x68/0x114 fs/dcache.c:1704
 generic_shutdown_super+0x68/0x324 fs/super.c:473
 kill_block_super+0x70/0xdc fs/super.c:1470
 deactivate_locked_super+0xac/0x120 fs/super.c:332
 deactivate_super+0xe4/0x104 fs/super.c:363
 cleanup_mnt+0x390/0x418 fs/namespace.c:1191
 __cleanup_mnt+0x20/0x30 fs/namespace.c:1198
 task_work_run+0x1ec/0x278 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x1fa0/0x2aa4 arch/arm64/kernel/signal.c:1151
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 186916
hardirqs last  enabled at (186915): [<ffff80000830fac4>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (186916): [<ffff800011a38ccc>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (186842): [<ffff800008030954>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (186840): [<ffff800008030920>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---
ocfs2: Unmounting device (7,0) on (node local)
VFS: Busy inodes after unmount of loop0 (ocfs2)
------------[ cut here ]------------
kernel BUG at fs/super.c:505!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4428 Comm: syz-executor Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : generic_shutdown_super+0x320/0x324 fs/super.c:503
lr : generic_shutdown_super+0x320/0x324 fs/super.c:503
sp : ffff8000212379a0
x29: ffff8000212379a0 x28: 1ffff00002a43a68 x27: dfff800000000000
x26: 0000000000000002 x25: 0000000000000002 x24: 1fffe0001b5aa0fb
x23: dfff800000000000 x22: ffff800011f76ec0 x21: 0000000000000000
x20: ffff8000158c9680 x19: ffff0000dad50000 x18: 0000000000000000
x17: ffff80018a3dd000 x16: ffff8000082d92bc x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033eaa5a3 x12: 0000000000ff0100
x11: ff00800008311668 x10: 0000000000000000 x9 : 9b207ee196e66f00
x8 : 9b207ee196e66f00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021237478 x4 : ffff800015304cc0 x3 : ffff8000085388c8
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 000000000000002f
Call trace:
 generic_shutdown_super+0x320/0x324 fs/super.c:503
 kill_block_super+0x70/0xdc fs/super.c:1470
 deactivate_locked_super+0xac/0x120 fs/super.c:332
 deactivate_super+0xe4/0x104 fs/super.c:363
 cleanup_mnt+0x390/0x418 fs/namespace.c:1191
 __cleanup_mnt+0x20/0x30 fs/namespace.c:1198
 task_work_run+0x1ec/0x278 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x1fa0/0x2aa4 arch/arm64/kernel/signal.c:1151
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: d0049520 91358000 911aa261 95d90926 (d4210000) 
---[ end trace 0000000000000000 ]---

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/26 09:45 linux-6.1.y 7c87defbd336 9c2d0995 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/01/06 14:37 linux-6.1.y 7dc732d24ff7 f3558dbf .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2026/04/29 20:53 linux-6.1.y 7c87defbd336 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan BUG: Dentry still in use in unmount
2026/04/26 09:06 linux-6.1.y 7c87defbd336 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2026/04/26 09:05 linux-6.1.y 7c87defbd336 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/11/19 03:13 linux-6.1.y f6e38ae624cf ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/11/19 03:11 linux-6.1.y f6e38ae624cf ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/11/17 06:12 linux-6.1.y f6e38ae624cf f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/11/17 06:12 linux-6.1.y f6e38ae624cf f7988ea4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/10/09 05:34 linux-6.1.y 882efbdd9d34 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/10/09 05:34 linux-6.1.y 882efbdd9d34 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/10/06 10:17 linux-6.1.y 882efbdd9d34 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/10/06 10:17 linux-6.1.y 882efbdd9d34 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/01/06 14:21 linux-6.1.y 7dc732d24ff7 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
2025/01/06 14:19 linux-6.1.y 7dc732d24ff7 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: Dentry still in use in unmount
* Struck through repros no longer work on HEAD.