Public bug reported:
Bug Report: lsblk -f enters infinite output loop due to loop device
handling issue
Summary
lsblk -f causes an infinite output loop and does not terminate on Ubuntu
24.04.4 LTS. The command continuously prints blank lines until manually
interrupted with Ctrl+C.
The issue appears to be related to filesystem information probing of
loop devices.
System Information
Operating System: Ubuntu 24.04.4 LTS
Hardware: Intel Core i5-4210U, 4GB RAM, 500 GB HDD
lsblk version: lsblk from util-linux 2.39.3
Problem Description
1. When running ' lsblk -f ' the command does not complete. Instead, the
terminal continuously prints blank lines indefinitely.
2. The command has to be stopped manually using Ctrl+C
3. The normal lsblk command may also reproduce the issue.
Steps to Reproduce
1. Boot Ubuntu 24.04.4 LTS.
2. Open Terminal.
3. Run lsblk -f
4. Observe that the command does not return to the shell prompt.
5. Terminal continues printing blank lines until interrupted.
Expected Behaviour
lsblk -f should display block devices with filesystem information and
then exit normally.
Example:
NAME FSTYPE LABEL UUID MOUNTPOINTS
sda
├─sda1 ntfs
├─sda2 ntfs
├─sda4 ext4
└─sda6 ext4 /
Actual Behaviour
lsblk -f enters an endless loop and continuously outputs blank lines.
The command never finishes without user interruption.
Additional Tests
1. lsblk version
Command: lsblk --version
Output: lsblk from util-linux 2.39.3
2. Full block device listing
Command: lsblk -a
Output shows a large number of loop devices:
loop0 7:0 201.3M loop /snap/brave/661
loop1 7:1 201.3M loop /snap/brave/658
...
loop56 7:56 182.3M loop /snap/yt-dlp/1337
loop57 7:57 0B loop
The system contains 58 loop devices:
/dev/loop0
...
/dev/loop57
Most are Snap package loop mounts.
3. Loop devices
Command: ls /dev/loop*
Output confirms the presence of:
/dev/loop0
/dev/loop1
...
/dev/loop57
/dev/loop-control
Disk Layout
Output from lsblk -a:
sda 465.8G disk
├─sda1 100M part
├─sda2 90G part
├─sda3 512B part
├─sda4 185.4G part
├─sda5 3G part
└─sda6 187.2G part /
Additional devices:
sr0 1024M rom
zram0 2.8G swap
Other Storage Tools Tested
The following tools work normally:
blkid
fdisk
GParted
They correctly detect partitions and filesystems.
The problem appears limited to lsblk.
Possible Cause
The problem may be caused by lsblk filesystem probing entering an
infinite loop while processing loop devices created by Snap packages.
The presence of:
loop57 7:57 0B loop
may also be relevant.
Additional Information
The executable being used:
Command: type lsblk
Output: lsblk is /usr/bin/lsblk
Requested Investigation
Please investigate whether util-linux lsblk in Ubuntu 24.04.4 LTS has an
issue handling loop devices or filesystem probing when a large number of
Snap loop mounts are present.
I can provide additional debugging information if required.
Attachments / Additional Logs Available
Can provide:
journalctl -b
dmesg
udevadm info
lsblk --json
lsblk --fs
if required.
-End of Report-
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: util-linux 2.39.3-9ubuntu6.5
ProcVersionSignature: Ubuntu 6.8.0-136.136-generic 6.8.12
Uname: Linux 6.8.0-136-generic x86_64
ApportVersion: 2.28.2-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: MATE
Date: Mon Jul 27 08:03:08 2026
InstallationDate: Installed on 2019-07-21 (2562 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
SourcePackage: util-linux
UpgradeStatus: Upgraded to noble on 2024-05-22 (795 days ago)
** Affects: util-linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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https://bugs.launchpad.net/bugs/2161864
Title:
lsblk -f gives endless loop of blank prints
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