[syzbot] [kernfs?] WARNING: locking bug in kernfs_remove_by_name_ns

[syzbot <syzbot+5ab23ab3166ecc1f994c@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ec2df4364666 Merge tag 'spi-fix-v6.16-rc7' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d098a2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=859f36d9ccbeaa3e
dashboard link: https://syzkaller.appspot.com/bug?extid=5ab23ab3166ecc1f994c
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3a245163b514/disk-ec2df436.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74d521df2d2b/vmlinux-ec2df436.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c35af89dc507/bzImage-ec2df436.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5ab23ab3166ecc1f994c@syzkaller.appspotmail.com

comedi comedi0: c6xdigio: a I/O base address must be specified
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 0 PID: 27407 at kernel/locking/lockdep.c:238 hlock_class kernel/locking/lockdep.c:238 [inline]
WARNING: CPU: 0 PID: 27407 at kernel/locking/lockdep.c:238 check_wait_context kernel/locking/lockdep.c:4857 [inline]
WARNING: CPU: 0 PID: 27407 at kernel/locking/lockdep.c:238 __lock_acquire+0x379/0xd20 kernel/locking/lockdep.c:5190
Modules linked in:
CPU: 0 UID: 0 PID: 27407 Comm: syz.1.5864 Not tainted 6.16.0-rc7-syzkaller-00140-gec2df4364666 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4857 [inline]
RIP: 0010:__lock_acquire+0x379/0xd20 kernel/locking/lockdep.c:5190
Code: eb 33 90 e8 b9 b6 17 03 85 c0 74 22 83 3d 92 a4 02 0e 00 75 19 90 48 c7 c7 05 eb b6 8d 48 c7 c6 ab 64 a6 8d e8 a8 d4 e5 ff 90 <0f> 0b 90 90 90 31 c0 48 8b 3c 24 0f b6 98 c4 00 00 00 41 8b 46 20
RSP: 0018:ffffc9000c487810 EFLAGS: 00010046
RAX: 8d19c7b7fdc9a800 RBX: ffffffff8b232418 RCX: 0000000000080000
RDX: ffffc9000cf89000 RSI: 000000000000365e RDI: 000000000000365f
RBP: 0000000000001c9b R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa6c R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880550ca968 R15: ffff8880550ca8f0
FS:  00007f2f114696c0(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d41fffc CR3: 000000005d526000 CR4: 00000000003526f0
DR0: 0000000000000004 DR1: 0004000000000002 DR2: 0000000000000408
DR3: 1000000100000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
 kernfs_remove_by_name_ns+0x3d/0x130 fs/kernfs/dir.c:1712
 remove_bind_files drivers/base/bus.c:605 [inline]
 bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
 comedi_device_detach+0x134/0x720 drivers/comedi/drivers.c:207
 comedi_device_attach+0x568/0x670 drivers/comedi/drivers.c:1003
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
 comedi_unlocked_ioctl+0x686/0xfc0 drivers/comedi/comedi_fops.c:2156
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 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: 0033:0x7f2f1058e9a9
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:00007f2f11469038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2f107b5fa0 RCX: 00007f2f1058e9a9
RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f2f10610d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f2f107b5fa0 R15: 00007fff884948c8
 </TASK>


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