On Mon, May 09, 2022 at 11:38:15AM -0700, Roman Gushchin wrote:
> Shrinker debugfs requires a way to represent memory cgroups without
> using full paths, both for displaying information and getting input
> from a user.
>
> Cgroup inode number is a perfect way, already used by bpf.
>
> This commit adds a couple of helper functions which will be used
> to handle memcg-aware shrinkers.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> ---
> include/linux/memcontrol.h | 21 +++++++++++++++++++++
> mm/memcontrol.c | 23 +++++++++++++++++++++++
> 2 files changed, 44 insertions(+)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index fe580cb96683..a6de9e5c1549 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -831,6 +831,15 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
> }
> struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
>
> +#ifdef CONFIG_SHRINKER_DEBUG
> +static inline unsigned long mem_cgroup_ino(struct mem_cgroup *memcg)
> +{
> + return memcg ? cgroup_ino(memcg->css.cgroup) : 0;
> +}
> +
> +struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino);
> +#endif
> +
> static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> {
> return mem_cgroup_from_css(seq_css(m));
> @@ -1324,6 +1333,18 @@ static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
> return NULL;
> }
>
> +#ifdef CONFIG_SHRINKER_DEBUG
> +static inline unsigned long mem_cgroup_ino(struct mem_cgroup *memcg)
> +{
> + return 0;
> +}
> +
> +static inline struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
> +{
> + return NULL;
> +}
> +#endif
> +
> static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> {
> return NULL;
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 04cea4fa362a..e6472728fa66 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5018,6 +5018,29 @@ struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
> return idr_find(&mem_cgroup_idr, id);
> }
>
> +#ifdef CONFIG_SHRINKER_DEBUG
> +struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
> +{
> + struct cgroup *cgrp;
> + struct cgroup_subsys_state *css;
> + struct mem_cgroup *memcg;
> +
> + cgrp = cgroup_get_from_id(ino);
> + if (!cgrp)
> + return ERR_PTR(-ENOENT);
> +
> + css = cgroup_get_e_css(cgrp, &memory_cgrp_subsys);
> + if (css)
> + memcg = container_of(css, struct mem_cgroup, css);
> + else
> + memcg = ERR_PTR(-ENOENT);
> +
> + cgroup_put(cgrp);
I think it's better to use css_put() here since the refcount is get
via cgroup_get_e_css() which returns a css struct.
Thanks.
> +
> + return memcg;
> +}
> +#endif
> +
> static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
> {
> struct mem_cgroup_per_node *pn;
> --
> 2.35.3
>
>
