[syzbot] [overlayfs?] WARNING in ovl_workdir_create (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d1d10cea0895 Merge tag 'perf-tools-fixes-for-v6.17-2025-09..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14fba87c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=429771c55b615e85
dashboard link: https://syzkaller.appspot.com/bug?extid=078954d5ad423349aa78
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fca0faadbf1b/disk-d1d10cea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aa812ff26c41/vmlinux-d1d10cea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0cf89313ffd8/bzImage-d1d10cea.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+078954...@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current)
WARNING: CPU: 1 PID: 6377 at kernel/locking/rtmutex_common.h:191 debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:191 [inline]
WARNING: CPU: 1 PID: 6377 at kernel/locking/rtmutex_common.h:191 rt_mutex_slowunlock+0x6ce/0x8a0 kernel/locking/rtmutex.c:1419
Modules linked in:
CPU: 1 UID: 0 PID: 6377 Comm: syz.2.75 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:191 [inline]
RIP: 0010:rt_mutex_slowunlock+0x6ce/0x8a0 kernel/locking/rtmutex.c:1419
Code: 0f b6 04 20 84 c0 0f 85 c6 01 00 00 83 3d 0d fc 24 04 00 75 19 90 48 c7 c7 c0 ed 0a 8b 48 c7 c6 00 ee 0a 8b e8 c3 bf 8a f6 90 <0f> 0b 90 90 90 e9 2f fa ff ff 90 0f 0b 90 e9 53 fe ff ff be 02 00
RSP: 0018:ffffc90004dd74a0 EFLAGS: 00010046
RAX: 0f6370d1171cee00 RBX: ffff88805d37f7e0 RCX: 0000000000080000
RDX: ffffc9000eb1b000 RSI: 000000000000170a RDI: 000000000000170b
RBP: ffffc90004dd7590 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1017124863 R12: dffffc0000000000
R13: ffff88805d37f790 R14: 0000000000000a02 R15: 1ffff920009bae9c
FS: 00007f7c0943d6c0(0000) GS:ffff8881269bf000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe813a53530 CR3: 00000000378d0000 CR4: 00000000003526f0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:879 [inline]
ovl_workdir_create+0x4da/0x8b0 fs/overlayfs/super.c:331
ovl_make_workdir fs/overlayfs/super.c:669 [inline]
ovl_get_workdir+0x32f/0x17c0 fs/overlayfs/super.c:827
ovl_fill_super+0x1365/0x35b0 fs/overlayfs/super.c:1406
vfs_get_super fs/super.c:1325 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1344
vfs_get_tree+0x92/0x2b0 fs/super.c:1815
do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
do_mount fs/namespace.c:4136 [inline]
__do_sys_mount fs/namespace.c:4347 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4324
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7c0b1febe9
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:00007f7c0943d038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f7c0b436090 RCX: 00007f7c0b1febe9
RDX: 0000200000000440 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007f7c0b281e19 R08: 0000200000000200 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7c0b436128 R14: 00007f7c0b436090 R15: 00007fff5ec39608
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup