Re: [PATCH] cgroup: Introduce css_is_online() helper

From: xiujianfeng
Date: Sat Apr 20 2024 - 05:50:40 EST


sorry, ignore this one, the tag should be [PATCH -next]

On 2024/4/20 17:38, Xiu Jianfeng wrote:
> Introduce css_is_online() helper to test if whether the specified
> css is online, avoid testing css.flags with CSS_ONLINE directly
> outside of cgroup.c.
>
> Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
> ---
> fs/fs-writeback.c | 2 +-
> include/linux/cgroup.h | 9 +++++++++
> include/linux/memcontrol.h | 2 +-
> kernel/cgroup/cgroup-internal.h | 2 +-
> mm/memcontrol.c | 2 +-
> mm/page_owner.c | 2 +-
> 6 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 92a5b8283528..bb84c6a2fa8e 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -916,7 +916,7 @@ void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page,
> folio = page_folio(page);
> css = mem_cgroup_css_from_folio(folio);
> /* dead cgroups shouldn't contribute to inode ownership arbitration */
> - if (!(css->flags & CSS_ONLINE))
> + if (!css_is_online(css))
> return;
>
> id = css->id;
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 2150ca60394b..e6b6f3418da8 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -346,6 +346,15 @@ static inline bool css_is_dying(struct cgroup_subsys_state *css)
> return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
> }
>
> +/*
> + * css_is_online - test whether the specified css is online
> + * @css: target css
> + */
> +static inline bool css_is_online(struct cgroup_subsys_state *css)
> +{
> + return !!(css->flags & CSS_ONLINE);
> +}
> +
> static inline void cgroup_get(struct cgroup *cgrp)
> {
> css_get(&cgrp->self);
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 8f332b4ae84c..cd6b3bfd070f 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -939,7 +939,7 @@ static inline bool mem_cgroup_online(struct mem_cgroup *memcg)
> {
> if (mem_cgroup_disabled())
> return true;
> - return !!(memcg->css.flags & CSS_ONLINE);
> + return css_is_online(&memcg->css);
> }
>
> void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
> diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
> index 520b90dd97ec..feeaf172844d 100644
> --- a/kernel/cgroup/cgroup-internal.h
> +++ b/kernel/cgroup/cgroup-internal.h
> @@ -183,7 +183,7 @@ extern struct list_head cgroup_roots;
>
> static inline bool cgroup_is_dead(const struct cgroup *cgrp)
> {
> - return !(cgrp->self.flags & CSS_ONLINE);
> + return !css_is_online(&cgrp->self);
> }
>
> static inline bool notify_on_release(const struct cgroup *cgrp)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7703ced535a3..e77e9e1911e6 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -405,7 +405,7 @@ ino_t page_cgroup_ino(struct page *page)
> /* page_folio() is racy here, but the entire function is racy anyway */
> memcg = folio_memcg_check(page_folio(page));
>
> - while (memcg && !(memcg->css.flags & CSS_ONLINE))
> + while (memcg && !css_is_online(&memcg->css))
> memcg = parent_mem_cgroup(memcg);
> if (memcg)
> ino = cgroup_ino(memcg->css.cgroup);
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 75c23302868a..7accb25e6fe6 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -523,7 +523,7 @@ static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
> if (!memcg)
> goto out_unlock;
>
> - online = (memcg->css.flags & CSS_ONLINE);
> + online = css_is_online(&memcg->css);
> cgroup_name(memcg->css.cgroup, name, sizeof(name));
> ret += scnprintf(kbuf + ret, count - ret,
> "Charged %sto %smemcg %s\n",