I partitioned and formatted my two new drives and suddenly my CPU usage went up to half of my available processing power. I checked and there were several processes, one of which was systemd-udevd. After stopping the service via systemctl stop systemd-udevd everything was fine again. But the problem always reoccured after a restart right after login or when i mounted/unmounted a fs from one of my new drives.

I checked udevadm monitor and saw a scrolling terminal, always showing the same change events.

UDEV  [359.270329] change   /devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sdb/sdb3 (block)
KERNEL[359.275809] change   /devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sdb/sdb2 (block)
KERNEL[359.282183] change   /devices/virtual/block/dm-2 (block)
UDEV  [359.286170] change   /devices/virtual/block/dm-3 (block)

I took several approaches and finally found the reason:


This ext4 feature provides multiple mount protection (MMP). MMP
helps to protect the filesystem from being multiply mounted and
is useful in shared storage environments.

I enabled this feature on all file systems and after disabling it, everything works fine now. I want to file a bug, but i can't fine a bug-tracker for udev. All i found is the freedesktop page of systemd which is told to be the current project page. Anyone knows a place to file this bug?

1 Answer 1


Update Jan 17, 2022: the issue was fixed in this pull request: https://github.com/storaged-project/udisks/pull/949

I was affected by the same issue and narrowed it down to the same root cause as you, but found your question only after the fact. Additionally, I was able to correlate the issue with udisks2 >= 2.7.6. So if you require MMP, you might want to consider downgrading.

The corresponding GitHub Issue with the discussion can be found here: https://github.com/storaged-project/udisks/issues/946

  • My current version is 2.9.2-2+deb11u1 and the problem still persists. Luckily, i just "wanted" and don't "needed" it. Currently i'm "enjoying" GRUB denying EXT4, if any of the metadata_csum_seed,ea_inode,casefold,large_dir features are enabled.
    – WGRM
    Commented Jan 3, 2022 at 10:55

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