Hi, Thorsten here, the Linux kernel's regression tracker.

I noticed a regression report in bugzilla.kernel.org. As many (most?) kernel developers don't keep an eye on it, I decided to forward it by mail (note, the reporter *is not* CCed to this mail, see[1]).

Note, it's a stable regression, so it's a bit unclear who's responsible. I decided to forward it nevertheless, as some of you might want to be aware of this or might even have an idea what's wrong.

Quoting from https://bugzilla.kernel.org/show_bug.cgi?id=217225 :

runrin 2023-03-21 17:49:34 UTC

I occasionally manage my fan speed manually by changing the `level' in `/proc/acpi/ibm/fan'. As of upgrading to 6.1.20, I am now getting the following error when attempting to change the fan speed:

$ echo 'level auto' > /proc/acpi/ibm/fan echo: write error: invalid argument

While troubleshooting, I tried double checking that fan_control had been set to 1 as noted in the documentation.

I recently upgraded my kernel a few versions at once, so unfortunately i can't be sure when this bug originated. It was working with 6.1.15, and since upgrading to 6.1.20 it is no longer working.

See the ticket for more details. The reporter was already asked to bisect. I'll ask to consider testing latest mainline.

[TLDR for the rest of this mail: I'm adding this report to the list of tracked Linux kernel regressions; the text you find below is based on a few templates paragraphs you might have encountered already in similar form.]

BTW, let me use this mail to also add the report to the list of tracked regressions to ensure it's doesn't fall through the cracks:

#regzbot introduced: v6.1.15..v6.1.20 https://bugzilla.kernel.org/show_bug.cgi?id=217225 #regzbot title: platform: thinkpad: can no longer alter /proc/acpi/ibm/fan #regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already discussed somewhere else? It was fixed already? You want to clarify when the regression started to happen? Or point out I got the title or something else totally wrong? Then just reply and tell me -- ideally while also telling regzbot about it, as explained by the page listed in the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing to the report (e.g. the buzgzilla ticket and maybe this mail as well, if this thread sees some discussion). See page linked in footer for details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr If I did something stupid, please tell me, as explained on that page.

[1] because bugzilla.kernel.org tells users upon registration their "email address will never be displayed to logged out users"