Bug#946791: io.weight cannot be enabled in recent Debian kernel package

[Ryutaroh Matsumoto]

Source: linux
Followup-For: Bug #946791
Control: tags -1 + patch

Dear Maintainer,

I reported that IOWeight config item in systemd has no effect
on recent Debian kernels. I found the root cause.
io.weight was changed to io.bfq.weight, and recent systemd sets
values of IOWeight to io.bfq.weight as

https://github.com/systemd/systemd/commit/2dbc45aea747f25cc1c3848fded2ec0062f96bcf

For io.bfq.weight to appear in cgroup v2 filesystem, the bfq kernel
module must be loaded. Addition of "bfq" to /etc/initramfs-tools/modules
solved this issue. Since the systemd needs bfq module to be loaded,
changing CONFIG_IOSCHED_BFQ=m to CONFIG_IOSCHED_BFQ=y in kernel config
seems suitable.

If the Debian kernel team considers this issue to be handled by another
package, e.g. initramfs-tools or systemd, please reassign this.
If this issue is considered not being a bug, please close this.

Best regards, Ryutaroh Matsumoto

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 5.4.0-trunk-amd64 (SMP w/2 CPU cores)
Locale: LANG=ja_JP.UTF-8, LC_CTYPE=ja_JP.UTF-8 (charmap=UTF-8), LANGUAGE=ja_JP.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled