[PATCH v4 1/7] mm: postpone kmem_cache memcg pointer initialization to memcg_link_cache()

Roman Gushchin
2019-05-14T21:45:03Z

Initialize kmem_cache->memcg_params.memcg pointer in
memcg_link_cache() rather than in init_memcg_params().

Once kmem_cache will hold a reference to the memory cgroup,
it will simplify the refcounting.

For non-root kmem_caches memcg_link_cache() is always called
before the kmem_cache becomes visible to a user, so it's safe.

Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
mm/slab.c | 2 +-
mm/slab.h | 5 +++--
mm/slab_common.c | 14 +++++++-------
mm/slub.c | 2 +-
4 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 2915d912e89a..f6eff59e018e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1268,7 +1268,7 @@ void __init kmem_cache_init(void)
nr_node_ids * sizeof(struct kmem_cache_node *),
SLAB_HWCACHE_ALIGN, 0, 0);
list_add(&kmem_cache->list, &slab_caches);
- memcg_link_cache(kmem_cache);
+ memcg_link_cache(kmem_cache, NULL);
slab_state = PARTIAL;

/*
diff --git a/mm/slab.h b/mm/slab.h
index 43ac818b8592..6a562ca72bca 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -289,7 +289,7 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order,
}

extern void slab_init_memcg_params(struct kmem_cache *);
-extern void memcg_link_cache(struct kmem_cache *s);
+extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg);
extern void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s,
void (*deact_fn)(struct kmem_cache *));

@@ -344,7 +344,8 @@ static inline void slab_init_memcg_params(struct kmem_cache *s)
{
}

-static inline void memcg_link_cache(struct kmem_cache *s)
+static inline void memcg_link_cache(struct kmem_cache *s,
+ struct mem_cgroup *memcg)
{
}

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 58251ba63e4a..6e00bdf8618d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -140,13 +140,12 @@ void slab_init_memcg_params(struct kmem_cache *s)
}

static int init_memcg_params(struct kmem_cache *s,
- struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+ struct kmem_cache *root_cache)
{
struct memcg_cache_array *arr;

if (root_cache) {
s->memcg_params.root_cache = root_cache;
- s->memcg_params.memcg = memcg;
INIT_LIST_HEAD(&s->memcg_params.children_node);
INIT_LIST_HEAD(&s->memcg_params.kmem_caches_node);
return 0;
@@ -221,11 +220,12 @@ int memcg_update_all_caches(int num_memcgs)
return ret;
}

-void memcg_link_cache(struct kmem_cache *s)
+void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg)
{
if (is_root_cache(s)) {
list_add(&s->root_caches_node, &slab_root_caches);
} else {
+ s->memcg_params.memcg = memcg;
list_add(&s->memcg_params.children_node,
&s->memcg_params.root_cache->memcg_params.children);
list_add(&s->memcg_params.kmem_caches_node,
@@ -244,7 +244,7 @@ static void memcg_unlink_cache(struct kmem_cache *s)
}
#else
static inline int init_memcg_params(struct kmem_cache *s,
- struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+ struct kmem_cache *root_cache)
{
return 0;
}
@@ -384,7 +384,7 @@ static struct kmem_cache *create_cache(const char *name,
s->useroffset = useroffset;
s->usersize = usersize;

- err = init_memcg_params(s, memcg, root_cache);
+ err = init_memcg_params(s, root_cache);
if (err)
goto out_free_cache;

@@ -394,7 +394,7 @@ static struct kmem_cache *create_cache(const char *name,

s->refcount = 1;
list_add(&s->list, &slab_caches);
- memcg_link_cache(s);
+ memcg_link_cache(s, memcg);
out:
if (err)
return ERR_PTR(err);
@@ -997,7 +997,7 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,

create_boot_cache(s, name, size, flags, useroffset, usersize);
list_add(&s->list, &slab_caches);
- memcg_link_cache(s);
+ memcg_link_cache(s, NULL);
s->refcount = 1;
return s;
}
diff --git a/mm/slub.c b/mm/slub.c
index cd04dbd2b5d0..c5646cb02055 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4215,7 +4215,7 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
}
slab_init_memcg_params(s);
list_add(&s->list, &slab_caches);
- memcg_link_cache(s);
+ memcg_link_cache(s, NULL);
return s;
}

--
2.20.1