Re: [PATH v3] cgroup: add cgroup_favordynmods= command-line option

Re: [PATH v3] cgroup: add cgroup_favordynmods= command-line option

[Michal Koutný]

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On Tue, Sep 26, 2023 at 09:16:17PM +0000, Luiz Capitulino <luizcap@amazon.com> wrote:
> We have a need of using favordynmods with cgroup v1, which doesn't support
> changing mount flags during remount. Enabling CONFIG_CGROUP_FAVOR_DYNMODS at
> build-time is not an option because we want to be able to selectively
> enable it for certain systems.
> 
> This commit addresses this by introducing the cgroup_favordynmods=
> command-line option. This option works for both cgroup v1 and v2 and also
> allows for disabling favorynmods when the kernel built with
> CONFIG_CGROUP_FAVOR_DYNMODS=y.
> 
> Also, note that when cgroup_favordynmods=true favordynmods is never
> disabled in cgroup_destroy_root().
> 
> Signed-off-by: Luiz Capitulino <luizcap@amazon.com>
> ---
>  .../admin-guide/kernel-parameters.txt          |  4 ++++
>  kernel/cgroup/cgroup.c                         | 18 ++++++++++++++----
>  2 files changed, 18 insertions(+), 4 deletions(-)

Thanks,

Reviewed-by: Michal Koutný <mkoutny@suse.com>


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Re: [External] : [PATH v3] cgroup: add cgroup_favordynmods= command-line option

[Kamalesh Babulal]

On 9/27/23 02:46, Luiz Capitulino wrote:
> We have a need of using favordynmods with cgroup v1, which doesn't support
> changing mount flags during remount. Enabling CONFIG_CGROUP_FAVOR_DYNMODS at
> build-time is not an option because we want to be able to selectively
> enable it for certain systems.
> 
> This commit addresses this by introducing the cgroup_favordynmods=
> command-line option. This option works for both cgroup v1 and v2 and also
> allows for disabling favorynmods when the kernel built with
> CONFIG_CGROUP_FAVOR_DYNMODS=y.
> 
> Also, note that when cgroup_favordynmods=true favordynmods is never
> disabled in cgroup_destroy_root().
> 
> Signed-off-by: Luiz Capitulino <luizcap@amazon.com>

The patch looks good to me, I have also boot tested it with combinations of
CONFIG_CGROUP_FAVOR_DYNMODS={y, n}, while passing the kernel parameter
cgroup_favordynmods={true, false} to the command line and works as expected.

Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>