Package: systemd
Version: 261.1-2
Severity: important
X-Debbugs-Cc: [email protected]
= Steps to reproduce =
0. Let's assume we have a block device with some partitions on it:
```
$ lsblk /dev/nbd0
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
nbd0 43:0 0 20G 0 disk
├─nbd0p1 43:1 0 100M 0 part
└─nbd0p2 43:2 0 19.9G 0 part
```
1. Create a filesystem on one of the partitions:
```
$ sudo mkfs.ext4 /dev/nbd0p2
mke2fs 1.47.2 (1-Jan-2025)
Discarding device blocks: done
Creating filesystem with 5216768 4k blocks and 1305600 inodes
Filesystem UUID: a052641a-2c21-4ce2-aaff-8d37145822d8
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
```
2. mount the newly created filesystem somewhere and create a folder inside it:
```
$ mkdir mnt
$ sudo mount -o relatime /dev/nbd0p2 mnt/
$ sudo mkdir mnt/dev
```
3. bind /dev hierarchy to the newly created folder:
```
$ sudo mount --rbind --make-rslave /dev mnt/dev/
```
4. recursively umount the partition:
```
$ sudo umount -R mnt
```
= Expected result =
The partition's underlying device should not be in use.
= Actual result =
systemd latches onto the device:
```
$ sudo mkfs.ext4 /dev/nbd0p2
mke2fs 1.47.2 (1-Jan-2025)
/dev/nbd0p2 is apparently in use by the system; will not make a filesystem
here!
```
Additionally in case of nbd devices, an attempt to disconnect causes I/O
errors:
```
$ sudo qemu-nbd --disconnect /dev/nbd0
/dev/nbd0 disconnected
morgwai@vm-trixie:~/systemd-sux$ journalctl --since=2026-07-03T22:15
--until=2026-07-03T22:16
Jul 03 22:15:20 vm-trixie sudo[3642]: morgwai : TTY=pts/0 ;
PWD=/home/morgwai/systemd-sux ; USER=root ; COMMAND=/usr/bin/qemu-nbd
--disconnect /dev/nbd0
Jul 03 22:15:20 vm-trixie sudo[3642]: pam_unix(sudo:session): session opened
for user root(uid=0) by morgwai(uid=1000)
Jul 03 22:15:20 vm-trixie kernel: block nbd0: NBD_DISCONNECT
Jul 03 22:15:20 vm-trixie kernel: block nbd0: Disconnected due to user request.
Jul 03 22:15:20 vm-trixie kernel: block nbd0: shutting down sockets
Jul 03 22:15:20 vm-trixie sudo[3642]: pam_unix(sudo:session): session closed
for user root
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 0 op 0x0:(READ)
flags 0x80700 phys_seg 16 prio class 2
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 0 op 0x0:(READ)
flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 2048 op
0x0:(READ) flags 0x80700 phys_seg 16 prio class 2
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 2048 op
0x0:(READ) flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0p1, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 0 op 0x0:(READ)
flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 0 op 0x0:(READ)
flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie udisksd[961]: Partitions found on device '/dev/nbd0'
but couldn't read partition table signature: Failed to assign the new context
to disk '/dev/nbd0': Input/output error
Jul 03 22:15:20 vm-trixie udisksd[961]: Partitions found on device '/dev/nbd0'
but couldn't read partition table signature: Failed to assign the new context
to disk '/dev/nbd0': Input/output error
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 206880 op
0x0:(READ) flags 0x80700 phys_seg 8 prio class 2
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 206880 op
0x0:(READ) flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0p2, logical block
4, async page read
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 41940864 op
0x0:(READ) flags 0x80700 phys_seg 11 prio class 2
Jul 03 22:15:20 vm-trixie kernel: I/O error, dev nbd0, sector 41940864 op
0x0:(READ) flags 0x800000 phys_seg 1 prio class 2
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0p2, logical block
5216752, async page read
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0, logical block
0, async page read
Jul 03 22:15:20 vm-trixie kernel: Buffer I/O error on dev nbd0p1, logical block
0, async page read
```
From then on, the nbd device becomes unusable: attempts to connect it to a
qcow2 file result in subsequent I/O errors.
This also affects physical removable devices in a similar way, preventing their
clean removal:
```
$ sudo eject /dev/sda
eject: cannot open /dev/sda: Device or resource busy
```
Disconnecting produces the following errors in logs:
```
Jul 05 04:27:21 morgwai-x4tuxedo kernel: usb 3-2: USB disconnect, device number
5
Jul 05 04:27:21 morgwai-x4tuxedo kernel: EXT4-fs (sda5): shut down requested
(2)
Jul 05 04:27:21 morgwai-x4tuxedo kernel: Aborting journal on device sda5-8.
Jul 05 04:27:21 morgwai-x4tuxedo kernel: device offline error, dev sda, sector
126885888 op 0x1:(WRITE) flags 0x9800 phys_seg 1 prio class 2
Jul 05 04:27:21 morgwai-x4tuxedo kernel: Buffer I/O error on dev sda5, logical
block 1081344, lost sync page write
Jul 05 04:27:21 morgwai-x4tuxedo kernel: JBD2: I/O error when updating journal
superblock for sda5-8.
```
On Devuan Excalibur this works perfectly fine, so this seems to be a systemd
issue.
-- Package-specific info:
-- System Information:
Debian Release: 13.5
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500,
'stable'), (90, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 7.1.1+tbfive2-amd64 (SMP w/24 CPU threads; PREEMPT)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE,
TAINT_UNSIGNED_MODULE
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8),
LANGUAGE=en_IE:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages systemd depends on:
ii libacl1 2.3.2-2+b1
ii libapparmor1 4.1.0-1
ii libc6 2.41-12+deb13u3
ii libmount1 2.41-5
ii libpam0g 1.7.0-5
ii libseccomp2 2.6.0-2
ii libselinux1 3.8.1-1
ii libssl3t64 3.5.6-1~deb13u2
ii libsystemd-shared 257.13-1~deb13u1
ii libsystemd0 257.13-1~deb13u1
ii mount 2.41-5
Versions of packages systemd recommends:
ii dbus [default-dbus-system-bus] 1.16.2-2
ii linux-sysctl-defaults 4.12.1
ii systemd-cryptsetup 257.13-1~deb13u1
ii systemd-timesyncd [time-daemon] 257.13-1~deb13u1
Versions of packages systemd suggests:
ii libtss2-tcti-device0t64 [libtss2-tcti-device0] 4.1.3-1.2
ii polkitd 126-2
pn systemd-boot <none>
ii systemd-container 257.13-1~deb13u1
pn systemd-homed <none>
pn systemd-repart <none>
pn systemd-resolved <none>
pn systemd-userdbd <none>
Versions of packages systemd is related to:
ii dbus-user-session 1.16.2-2
pn dracut <none>
ii initramfs-tools 0.148.4
ii libnss-systemd 257.13-1~deb13u1
ii libpam-systemd 257.13-1~deb13u1
ii udev 257.13-1~deb13u1
-- no debconf information
