syzbot


BUG: Dentry still in use in unmount

Status: upstream: reported C repro on 2025/10/06 19:49
Reported-by: syzbot+5ce2c2133ed448b7bb4f@syzkaller.appspotmail.com
First crash: 5d01h, last: 2d16h
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 C done 58 665d 1142d 25/29 fixed on 2024/01/20 21:18
android-5-10 BUG: Dentry still in use [unmount of ext4 loop0] -1 C error 63 1410d 1448d 0/2 closed as dup on 2021/10/28 13:08
upstream BUG: Dentry still in use in unmount (3) ocfs2 -1 C 7 85d 198d 0/29 upstream: reported C repro on 2025/03/27 01:13
upstream BUG: Dentry still in use in unmount (2) fs -1 1 303d 299d 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 C done 1184 1326d 1338d 2/2 fixed on 2022/02/25 03:20
android-54 BUG: Dentry still in use [unmount of ramfs ramfs] -1 C 476 1345d 1667d 0/2 auto-obsoleted due to no activity on 2023/04/21 02:49
linux-6.1 BUG: Dentry still in use in unmount origin:lts-only -1 C inconclusive 7 2d16h 278d 0/3 upstream: reported C repro on 2025/01/06 14:20

Sample crash report:
gfs2: fsid=syz:syz.0: first mount done, others may mount
------------[ cut here ]------------
BUG: Dentry ffff88806144f490{i=925,n=/}  still in use (3) [unmount of gfs2 loop0]
WARNING: CPU: 0 PID: 5950 at fs/dcache.c:1680 umount_check+0x186/0x1d0 fs/dcache.c:1672
Modules linked in:
CPU: 0 PID: 5950 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:umount_check+0x186/0x1d0 fs/dcache.c:1672
Code: ea ff 4d 8b 0f 49 81 c5 60 06 00 00 48 c7 c7 c0 cc b7 8a 48 89 de 4c 89 f2 48 89 d9 41 89 e8 41 55 e8 ae 99 5d ff 48 83 c4 08 <0f> 0b 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 89 f9 80 e1 07 80 c1
RSP: 0018:ffffc900033178f8 EFLAGS: 00010282
RAX: be92a052eaecb500 RBX: ffff88806144f490 RCX: ffff888026045a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000003 R08: ffffc900033174e7 R09: 1ffff92000662e9c
R10: dffffc0000000000 R11: fffff52000662e9d R12: dffffc0000000000
R13: ffff88807b352660 R14: 0000000000000925 R15: ffffffff8d2cb6c0
FS:  0000555582221500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d963fff CR3: 0000000076491000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 d_walk+0x4c/0x700 fs/dcache.c:1367
 do_one_tree+0x35/0xe0 fs/dcache.c:1687
 shrink_dcache_for_umount+0x69/0x110 fs/dcache.c:1703
 generic_shutdown_super+0x67/0x2b0 fs/super.c:665
 kill_block_super+0x44/0x90 fs/super.c:1660
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 gfs2_thaw_super+0x179/0x1e0 fs/gfs2/super.c:833
 do_vfs_ioctl+0x1232/0x1bb0 fs/ioctl.c:-1
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
 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: 0033:0x7fab4878eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffe13511d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fab489e5fa0 RCX: 00007fab4878eec9
RDX: 0000000000000000 RSI: 00000000c0045878 RDI: 0000000000000003
RBP: 00007fab48811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fab489e5fa0 R14: 00007fab489e5fa0 R15: 0000000000000002
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/09 05:25 linux-6.6.y e617101e5626 7e2882b3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan BUG: Dentry still in use in unmount
2025/10/09 05:03 linux-6.6.y e617101e5626 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan BUG: Dentry still in use in unmount
2025/10/06 19:48 linux-6.6.y e617101e5626 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan BUG: Dentry still in use in unmount
2025/10/06 19:48 linux-6.6.y e617101e5626 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan BUG: Dentry still in use in unmount
* Struck through repros no longer work on HEAD.