linux-kernel - Re: [PATH v2] cgroup: add cgroup_favordynmods= command-line option

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Message-ID: <236f84be-26b0-758d-3d3f-380e536f72c2@amazon.com>
Date:   Thu, 7 Sep 2023 11:16:41 -0400
From:   Luiz Capitulino <luizcap@...zon.com>
To:     Michal Koutný <mkoutny@...e.com>
CC:     <tj@...nel.org>, <lizefan.x@...edance.com>, <hannes@...xchg.org>,
        <cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <longman@...hat.com>, <lcapitulino@...il.com>
Subject: Re: [PATH v2] cgroup: add cgroup_favordynmods= command-line option



On 2023-09-07 11:06, Michal Koutný wrote:
> On Wed, Sep 06, 2023 at 12:57:12AM +0000, Luiz Capitulino <luizcap@...zon.com> wrote:
>> We have a need of using favordynmods with cgroup v1, which doesn't support
>> changing mount flags during remount. Enabling CONFIG_FAVOR_DYNMODS at
>> build-time is not an option because we want to be able to selectively
>> enable it for certain systems.
> 
> Could this be implemented by a utility that would read /proc/cmdline
> (while kernel ignores the arg) and remount respective hierarchies
> accordingly? Or what do I miss?

Yeah, this works for cgroup v2 but my understanding is that cgroup v1
doesn't support changing flags in remount, take a look at
cgroup1_reconfigure().

- Luiz