On Fri, May 18, 2018 at 11:43:53AM +0300, Kirill Tkhai wrote:
> This will be used in next patch.
>
> Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
> ---
> include/linux/memcontrol.h | 10 ++++++++++
> mm/memcontrol.c | 5 -----
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 7ae1b94becf3..cd44c1fac22b 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -311,6 +311,11 @@ struct mem_cgroup {
>
> extern struct mem_cgroup *root_mem_cgroup;
>
> +static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
> +{
> + return (memcg == root_mem_cgroup);
> +}
> +
> static inline bool mem_cgroup_disabled(void)
> {
> return !cgroup_subsys_enabled(memory_cgrp_subsys);
> @@ -780,6 +785,11 @@ void mem_cgroup_split_huge_fixup(struct page *head);
>
> struct mem_cgroup;
>
> +static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
> +{
> + return false;
> +}
> +
This stub must return true as one can think of !MEMCG as of the case
when there's the only cgroup - the root.
