[PATCH 5/9] mm: memcontrol: move memcg_online_kmem() to mem_cgroup_css_online()

Muchun Song
2021-04-28T09:54:29Z

Move memcg_online_kmem() to mem_cgroup_css_online() to simplify the
code. In this case, we can remove memcg_free_kmem().

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/memcontrol.c | 41 ++++++++++++++++-------------------------
1 file changed, 16 insertions(+), 25 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9b9a5368a3e9..1610d501e7b5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3460,6 +3460,9 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)
if (cgroup_memory_nokmem)
return 0;

+ if (mem_cgroup_is_root(memcg))
+ return 0;
+
BUG_ON(memcg->kmemcg_id >= 0);

memcg_id = memcg_alloc_cache_id();
@@ -3486,6 +3489,9 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
struct mem_cgroup *parent;
int kmemcg_id;

+ if (mem_cgroup_is_root(memcg))
+ return;
+
parent = parent_mem_cgroup(memcg);
if (!parent)
parent = root_mem_cgroup;
@@ -3499,14 +3505,6 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
memcg_reparent_list_lrus(memcg, parent);

memcg_free_cache_id(kmemcg_id);
- memcg->kmemcg_id = -1;
-}
-
-static void memcg_free_kmem(struct mem_cgroup *memcg)
-{
- /* css_alloc() failed, offlining didn't happen */
- if (unlikely(memcg->kmemcg_id != -1))
- memcg_offline_kmem(memcg);
}
#else
static int memcg_online_kmem(struct mem_cgroup *memcg)
@@ -3516,9 +3514,6 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)
static void memcg_offline_kmem(struct mem_cgroup *memcg)
{
}
-static void memcg_free_kmem(struct mem_cgroup *memcg)
-{
-}
#endif /* CONFIG_MEMCG_KMEM */

static int memcg_update_kmem_max(struct mem_cgroup *memcg,
@@ -5047,7 +5042,6 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct mem_cgroup *parent = mem_cgroup_from_css(parent_css);
struct mem_cgroup *memcg, *old_memcg;
- long error = -ENOMEM;

old_memcg = set_active_memcg(parent);
memcg = mem_cgroup_alloc();
@@ -5077,38 +5071,36 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
}

/* The following stuff does not apply to the root */
- error = memcg_online_kmem(memcg);
- if (error)
- goto fail;
-
if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
static_branch_inc(&memcg_sockets_enabled_key);

return &memcg->css;
-fail:
- mem_cgroup_id_remove(memcg);
- mem_cgroup_free(memcg);
- return ERR_PTR(error);
}

static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);

+ if (memcg_online_kmem(memcg))
+ goto remove_id;
+
/*
* A memcg must be visible for expand_shrinker_info()
* by the time the maps are allocated. So, we allocate maps
* here, when for_each_mem_cgroup() can't skip it.
*/
- if (alloc_shrinker_info(memcg)) {
- mem_cgroup_id_remove(memcg);
- return -ENOMEM;
- }
+ if (alloc_shrinker_info(memcg))
+ goto offline_kmem;

/* Online state pins memcg ID, memcg ID pins CSS */
refcount_set(&memcg->id.ref, 1);
css_get(css);
return 0;
+offline_kmem:
+ memcg_offline_kmem(memcg);
+remove_id:
+ mem_cgroup_id_remove(memcg);
+ return -ENOMEM;
}

static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
@@ -5166,7 +5158,6 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
cancel_work_sync(&memcg->high_work);
mem_cgroup_remove_from_trees(memcg);
free_shrinker_info(memcg);
- memcg_free_kmem(memcg);
mem_cgroup_free(memcg);
}

--
2.11.0