When working with ext4 filesystems in Linux, you might encounter this stubborn error during remount operations. The system is essentially telling you it can't process some leftover inodes (data structures representing files) that became "orphaned" - meaning they exist but aren't properly linked in the directory structure.

Normally, you'd expect these solutions to work:

# Attempt 1: Simple remount
sudo mount -o remount,rw /mountpoint

# Attempt 2: Unmount and remount
sudo umount /mountpoint
sudo mount /dev/yourdevice /mountpoint

But with orphan inodes, you'll hit roadblocks. The unmount fails because the kernel still holds references to these orphaned inodes, even when no user processes appear to be using them (as you've seen with lsof and fuser).

Method 1: Forced Remount with Emergency Option

Try this nuclear option when you absolutely need write access:

sudo mount -o remount,rw,errors=continue /mountpoint

This tells the filesystem to continue despite errors, though it's not recommended for production systems as it might lead to data corruption.

Method 2: Comprehensive Cleanup Procedure

For a safer approach:

# First, find what's holding the mount
sudo lsof +f -- /mountpoint
sudo fuser -vm /mountpoint

# If truly nothing shows up, force unmount
sudo umount -l /mountpoint  # lazy unmount

# Then run a full filesystem check
sudo fsck -y /dev/yourdevice

# Finally remount
sudo mount /dev/yourdevice /mountpoint

Method 3: Kernel-Level Solution

For persistent cases, you might need to:

# Drop caches to release inode references
echo 2 | sudo tee /proc/sys/vm/drop_caches

# Then attempt unmount again
sudo umount /mountpoint

To avoid orphan inode situations:

1. Always properly unmount filesystems before shutdown
2. Consider adding errors=remount-ro to your fstab options
3. Schedule regular filesystem checks with tune2fs -c

When attempting to remount an EXT4 filesystem from readonly to read-write mode, you might encounter this stubborn error:

[2570543.520449] EXT4-fs (dm-0): Couldn't remount RDWR because of unprocessed orphan inode list. Please umount/remount instead

This occurs when the filesystem contains inodes marked as "orphaned" - files that were being modified during an unclean unmount or system crash. The filesystem preserves these to allow proper cleanup during the next mount.

Before attempting solutions, verify the actual mount status:

mount | grep /mountpoint
cat /proc/mounts | grep /mountpoint

If the filesystem shows as mounted but you can't unmount it (device is busy), try these diagnostic commands:

lsof +f -- /mountpoint
fuser -vm /mountpoint
ls -l /proc/*/fd/ | grep /mountpoint

When standard unmount fails, try these escalating approaches:

# First attempt lazy unmount
umount -l /mountpoint

# If that fails, try forcing the unmount
umount -f /mountpoint

# For really stuck cases, use nsenter to check mount namespace
nsenter -m -t $(pgrep -f /mountpoint) mount

When all else fails, these low-level methods can help:

# 1. Debug the filesystem (requires unmounted fs)
debugfs -w /dev/dm-0
debugfs: list_orphans
debugfs: purge_orphans
debugfs: quit

# 2. Use e2fsck (may cause data loss)
e2fsck -f -y /dev/dm-0

# 3. Kernel-level workaround (temporary)
echo 1 > /proc/sys/fs/rm_orphaned_inodes

To avoid orphan inode issues:

• Always use sync before unmounting critical filesystems
• Consider mounting with nobarrier for better crash consistency
• Implement proper filesystem journaling with data=journal mount option

Here's how I recently resolved this on a production database server:

# Identify the actual device
dmsetup info -c /dev/dm-0

# Check journal status
dumpe2fs -h /dev/dm-0 | grep 'Filesystem features'

# Forced recovery sequence
umount -f /dbdata
fsck.ext4 -f /dev/mapper/vgdb-dbdata
mount -o rw,remount /dbdata