DAMON not working on F41

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,
1

As topic, this is my setting

kernel="/boot/vmlinuz-6.13.5-200.fc41.x86_64"
args="ro rootflags=subvol=root no_timer_check console=tty1 console=ttyS0,115200n8 systemd.firstboot=off rootflags=subvol=root damon_reclaim.enabled=Y damon_reclaim.min_age=300000000 damon_reclaim.wmarks_high=950 damon_reclaim.wmarks_mid=950 damon_reclaim.wmarks_low=50 damon_reclaim.min_nr_regions=100 damon_reclaim.quota_sz=0"
root="UUID=815e66c2-6a8a-4984-a890-1a3c710bf933"
initrd="/boot/initramfs-6.13.5-200.fc41.x86_64.img"
title="Fedora Linux (6.13.5-200.fc41.x86_64) 41 (Cloud Edition)"
id="007c0c4cb8b843199bc33b4410ce8950-6.13.5-200.fc41.x86_64"

The default kernel does support, or at least should support

CONFIG_DAMON=y
CONFIG_DAMON_VADDR=y
CONFIG_DAMON_PADDR=y
CONFIG_DAMON_SYSFS=y
# CONFIG_DAMON_DBGFS_DEPRECATED is not set
CONFIG_DAMON_RECLAIM=y
# CONFIG_DAMON_LRU_SORT is not set

Am I doing something wrong or is it a bug?

3

Could you describe what you tried and what output you’re getting?

Thanks!

4

This is all I did. Typically, DAMON should be proactively looking for cold page and swap them which my case into zram. While there are kdamond process running which indicate monitoring is occuring, it is not performing the swapping part.

I did some local testing at hyper-v. The same parameters work out of box on default kernels of Almalinux 9 and RockyLinux 9, the default kernels are 5.x. I then self compile 6.12.18 kernel and it doesn’t work.

I googled and found out they used an outdated method to test damon.
https://lore.kernel.org/lkml/20250306011111.138928-1-sj@kernel.org/T/

debugfs has been deprecated for a long time.

TLDR. It is a kernel bug, where can I report this?

5

Kernel bugs can be reported at https://bugzilla.redhat.com/.
See How to file a bug :: Fedora Docs for more info