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VFS: Busy inodes after unmount (use-after-free)

Status: upstream: reported C repro on 2025/07/29 23:52
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+07910bd70ef5a5789202@syzkaller.appspotmail.com
First crash: 162d, last: 12d
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: VFS: Busy inodes after unmount (use-after-free) (log)
Repro: C syz .config
  
▶ ▼ Bug presence (3)
Date Name Commit Repro Result
2025/09/15 linux-6.6.y (ToT) 60a9e718726f C [report] VFS: Busy inodes after unmount (use-after-free)
2025/07/30 upstream (ToT) 4b290aae788e C [report] VFS: Busy inodes after unmount (use-after-free)
2025/09/15 upstream (ToT) f83ec76bf285 C Didn't crash
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-54 VFS: Busy inodes after unmount (use-after-free) 2 C 4 992d 1047d 0/2 auto-obsoleted due to no activity on 2023/08/20 15:35
upstream VFS: Busy inodes after unmount (use-after-free) (2) btrfs 2 C error 277 130d 242d 29/29 fixed on 2025/09/04 16:57
linux-6.1 VFS: Busy inodes after unmount (use-after-free) origin:lts-only 2 C inconclusive 1828 12h28m 1027d 0/3 upstream: reported C repro on 2023/03/18 09:53
android-5-15 VFS: Busy inodes after unmount (use-after-free) origin:downstream 2 C error done 2 945d 1047d 0/2 auto-obsoleted due to no activity on 2023/09/15 20:27
android-5-10 VFS: Busy inodes after unmount (use-after-free) 2 C done inconclusive 1 1047d 1047d 0/2 auto-obsoleted due to no activity on 2023/06/25 23:02
upstream VFS: Busy inodes after unmount (use-after-free) (3) isofs 2 C error 85 70d 100d 29/29 fixed on 2025/11/18 08:45
upstream VFS: Busy inodes after unmount (use-after-free) (4) jfs 2 C error 7 11d 14d 0/29 upstream: reported C repro on 2025/12/25 14:06
upstream VFS: Busy inodes after unmount (use-after-free) bcachefs 2 C error 55684 247d 1079d 28/29 fixed on 2025/05/06 15:33
linux-5.15 VFS: Busy inodes after unmount (use-after-free) missing-backport origin:lts-only 2 C unreliable 2395 1d01h 1026d 0/3 upstream: reported C repro on 2023/03/19 11:46
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/12/17 00:08 1h19m fix candidate upstream OK (0) job log
2025/09/08 07:53 1h54m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
VFS: Lookup of '' in ocfs2 loop0 would have caused loop
VFS: Lookup of '' in ocfs2 loop0 would have caused loop
ocfs2: Unmounting device (7,0) on (node local)
VFS: Busy inodes after unmount of loop0 (ocfs2)
------------[ cut here ]------------
kernel BUG at fs/super.c:697!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5877 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:generic_shutdown_super+0x2ad/0x2b0 fs/super.c:695
Code: e8 03 42 80 3c 28 00 74 08 4c 89 f7 e8 4c 75 f0 ff 49 8b 16 48 81 c3 60 06 00 00 48 c7 c7 a0 9f b7 8a 48 89 de e8 e3 a1 6f 08 <0f> 0b 90 66 0f 1f 00 55 41 57 41 56 53 48 89 fb 49 bf 00 00 00 00
RSP: 0018:ffffc900032d7bc0 EFLAGS: 00010246
RAX: 000000000000002f RBX: ffff888028f6e660 RCX: 87d3ad970195a300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff110051edcf2 R08: ffff8880b8f28c13 R09: 1ffff110171e5182
R10: dffffc0000000000 R11: ffffed10171e5183 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8d232180 R15: ffff888028f6e790
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d1aa015040 CR3: 0000000030bf9000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 kill_block_super+0x44/0x90 fs/super.c:1660
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x90b/0x23c0 kernel/exit.c:883
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7feed7f8f749
Code: Unable to access opcode bytes at 0x7feed7f8f71f.
RSP: 002b:00007ffe3c5da668 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007feed8013da2 RCX: 00007feed7f8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000028 R08: 00007ffe3c5d8406 R09: 00007ffe3c5db920
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3c5db920
R13: 00007feed8013d7d R14: 0000000000016e8d R15: 00007ffe3c5dc9f0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:generic_shutdown_super+0x2ad/0x2b0 fs/super.c:695
Code: e8 03 42 80 3c 28 00 74 08 4c 89 f7 e8 4c 75 f0 ff 49 8b 16 48 81 c3 60 06 00 00 48 c7 c7 a0 9f b7 8a 48 89 de e8 e3 a1 6f 08 <0f> 0b 90 66 0f 1f 00 55 41 57 41 56 53 48 89 fb 49 bf 00 00 00 00
RSP: 0018:ffffc900032d7bc0 EFLAGS: 00010246
RAX: 000000000000002f RBX: ffff888028f6e660 RCX: 87d3ad970195a300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff110051edcf2 R08: ffff8880b8f28c13 R09: 1ffff110171e5182
R10: dffffc0000000000 R11: ffffed10171e5183 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8d232180 R15: ffff888028f6e790
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d1a9fc7900 CR3: 000000002de70000 CR4: 00000000003506e0

Crashes (50):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/17 01:31 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/03 14:42 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/29 12:29 linux-6.6.y 4a243110dc88 fd2207e7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/08/02 11:32 linux-6.6.y 3a8ababb8b6a 7368264b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/07/30 11:21 linux-6.6.y dbcb8d8e4163 f8f2b4da .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/26 22:44 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/26 22:43 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/26 22:41 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/26 22:41 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/26 22:40 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/25 17:09 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/22 05:43 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/22 05:43 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/20 22:17 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/20 22:14 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/20 22:02 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/19 20:02 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/12/09 11:18 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/11/30 07:04 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/11/30 07:04 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/11/30 07:02 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/11/30 07:02 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/11/30 07:02 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/12 20:48 linux-6.6.y 655054d2c3c1 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/11 08:08 linux-6.6.y e617101e5626 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/05 19:37 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/05 19:36 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/05 19:36 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:23 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:20 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:18 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:17 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:15 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:14 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:10 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:10 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:07 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:07 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:04 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/10/03 11:04 linux-6.6.y f34f16e5c632 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
2025/07/29 23:52 linux-6.6.y dbcb8d8e4163 f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan VFS: Busy inodes after unmount (use-after-free)
* Struck through repros no longer work on HEAD.