Messages in this thread | | | Date | Tue, 5 Sep 2023 14:59:43 -0400 | Subject | Re: [PATH] cgroup: add cgroup_favordynmods= command-line option | From | Waiman Long <> |
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On 9/5/23 13:03, Luiz Capitulino wrote: > On Thu, Aug 31, 2023 at 10:20:46AM -0400, Luiz Capitulino 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. >> >> 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_FAVOR_DYNMODS=y. >> >> Signed-off-by: Luiz Capitulino <luizcap@amazon.com> > Hi, > > Would somebody take a look at this patch please? > > Thanks, > > - Luiz
The patch looks good to me. I do have a minor comment that it may be better to use the relatively new __ro_after_init qualifier instead of __read_mostly.
Cheers, Longman
>> --- >> Documentation/admin-guide/kernel-parameters.txt | 4 ++++ >> kernel/cgroup/cgroup.c | 14 +++++++++++--- >> 2 files changed, 15 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index 0c38a8af95ce..672f76a3c002 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -580,6 +580,10 @@ >> named mounts. Specifying both "all" and "named" disables >> all v1 hierarchies. >> >> + cgroup_favordynmods= [KNL] Enable or Disable favordynmods. >> + Format: { "true" | "false" } >> + Defaults to the value of CONFIG_CGROUP_FAVOR_DYNMODS. >> + >> cgroup.memory= [KNL] Pass options to the cgroup memory controller. >> Format: <string> >> nosocket -- Disable socket memory accounting. >> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c >> index 5fa95f86cb4d..b625825e270b 100644 >> --- a/kernel/cgroup/cgroup.c >> +++ b/kernel/cgroup/cgroup.c >> @@ -207,6 +207,8 @@ static u16 have_exit_callback __read_mostly; >> static u16 have_release_callback __read_mostly; >> static u16 have_canfork_callback __read_mostly; >> >> +static bool have_favordynmods __read_mostly = IS_ENABLED(CONFIG_CGROUP_FAVOR_DYNMODS); >> + >> /* cgroup namespace for init task */ >> struct cgroup_namespace init_cgroup_ns = { >> .ns.count = REFCOUNT_INIT(2), >> @@ -2265,9 +2267,9 @@ static int cgroup_init_fs_context(struct fs_context *fc) >> fc->user_ns = get_user_ns(ctx->ns->user_ns); >> fc->global = true; >> >> -#ifdef CONFIG_CGROUP_FAVOR_DYNMODS >> - ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS; >> -#endif >> + if (have_favordynmods) >> + ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS; >> + >> return 0; >> } >> >> @@ -6767,6 +6769,12 @@ static int __init enable_cgroup_debug(char *str) >> } >> __setup("cgroup_debug", enable_cgroup_debug); >> >> +static int __init cgroup_favordynmods_setup(char *str) >> +{ >> + return (kstrtobool(str, &have_favordynmods) == 0); >> +} >> +__setup("cgroup_favordynmods=", cgroup_favordynmods_setup); >> + >> /** >> * css_tryget_online_from_dir - get corresponding css from a cgroup dentry >> * @dentry: directory dentry of interest >> -- >> 2.40.1 >>
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