Sometimes we need to iterate over all child caches of a particular root
cache, e.g. when we are destroying it. Currently each root cache keeps
pointers to its children in its memcg_cache_params->memcg_caches_array
so that we can enumerate all active kmemcg ids dereferencing appropriate
array slots to get a memcg.
However, I'm going to make memcg clear the slots on offline to avoid
uncontrollable memcg_caches arrays growth. Hence to iterate over all
memcg caches of a particular root cache we have to link all memcg caches
to per root cache lists.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 2 +-
include/linux/slab.h | 3 +++
mm/memcontrol.c | 27 ++++++++++++---------------
mm/slab.c | 40 +++++++++++++++++++++++-----------------
mm/slab_common.c | 31 +++++++++++++++++--------------
mm/slub.c | 39 +++++++++++++++++++++++----------------
6 files changed, 79 insertions(+), 63 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4b4a26725cbb..c15cb0c9f413 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -451,7 +451,7 @@ __memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order);
void __memcg_uncharge_slab(struct kmem_cache *cachep, int order);
-int __memcg_cleanup_cache_params(struct kmem_cache *s);
+void __memcg_cleanup_cache_params(struct kmem_cache *s);
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
diff --git a/include/linux/slab.h b/include/linux/slab.h
index e6e6ddb769c7..bf94461ca82e 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -527,6 +527,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
* @memcg: pointer to the memcg this cache belongs to
* @list: list_head for the list of all caches in this memcg
* @root_cache: pointer to the global, root cache, this cache was derived from
+ * @siblings: list_head for the list of all child caches of the root_cache
* @nr_pages: number of pages that belongs to this cache.
*/
struct memcg_cache_params {
@@ -534,6 +535,7 @@ struct memcg_cache_params {
union {
struct {
struct rcu_head rcu_head;
+ struct list_head children;
struct kmem_cache *memcg_caches[0];
};
struct {
@@ -541,6 +543,7 @@ struct memcg_cache_params {
struct mem_cgroup *memcg;
struct list_head list;
struct kmem_cache *root_cache;
+ struct list_head siblings;
atomic_t nr_pages;
};
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index aa3111ac3b7e..3ee37189e57e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2914,6 +2914,10 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
return -ENOMEM;
new_params->is_root_cache = true;
+ INIT_LIST_HEAD(&new_params->children);
+ if (cur_params)
+ list_replace(&cur_params->children,
+ &new_params->children);
/*
* There is the chance it will be bigger than
@@ -2970,8 +2974,10 @@ int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
s->memcg_params->memcg = memcg;
s->memcg_params->root_cache = root_cache;
css_get(&memcg->css);
- } else
+ } else {
s->memcg_params->is_root_cache = true;
+ INIT_LIST_HEAD(&s->memcg_params->children);
+ }
return 0;
}
@@ -3090,24 +3096,15 @@ static inline void memcg_resume_kmem_account(void)
current->memcg_kmem_skip_account--;
}
-int __memcg_cleanup_cache_params(struct kmem_cache *s)
+void __memcg_cleanup_cache_params(struct kmem_cache *s)
{
- struct kmem_cache *c;
- int i, failed = 0;
+ struct memcg_cache_params *params, *tmp;
mutex_lock(&memcg_slab_mutex);
- for_each_memcg_cache_index(i) {
- c = cache_from_memcg_idx(s, i);
- if (!c)
- continue;
-
- memcg_unregister_cache(c);
-
- if (cache_from_memcg_idx(s, i))
- failed++;
- }
+ list_for_each_entry_safe(params, tmp,
+ &s->memcg_params->children, siblings)
+ memcg_unregister_cache(params->cachep);
mutex_unlock(&memcg_slab_mutex);
- return failed;
}
static void memcg_unregister_all_caches(struct mem_cgroup *memcg)
diff --git a/mm/slab.c b/mm/slab.c
index 1351725f7936..aed36c5b0bd9 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3780,29 +3780,35 @@ static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
return alloc_kmem_cache_node(cachep, gfp);
}
+static void memcg_do_tune_cpucache(struct kmem_cache *cachep, int limit,
+ int batchcount, int shared, gfp_t gfp)
+{
+#ifdef CONFIG_MEMCG_KMEM
+ struct memcg_cache_params *params;
+
+ if (!cachep->memcg_params ||
+ !cachep->memcg_params->is_root_cache)
+ return;
+
+ lockdep_assert_held(&slab_mutex);
+ list_for_each_entry(params,
+ &cachep->memcg_params->children, siblings) {
+ /* return value determined by the parent cache only */
+ __do_tune_cpucache(params->cachep, limit,
+ batchcount, shared, gfp);
+ }
+#endif
+}
+
static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
int batchcount, int shared, gfp_t gfp)
{
int ret;
- struct kmem_cache *c = NULL;
- int i = 0;
ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
-
- if (slab_state < FULL)
- return ret;
-
- if ((ret < 0) || !is_root_cache(cachep))
- return ret;
-
- VM_BUG_ON(!mutex_is_locked(&slab_mutex));
- for_each_memcg_cache_index(i) {
- c = cache_from_memcg_idx(cachep, i);
- if (c)
- /* return value determined by the parent cache only */
- __do_tune_cpucache(c, limit, batchcount, shared, gfp);
- }
-
+ if (!ret)
+ memcg_do_tune_cpucache(cachep, limit,
+ batchcount, shared, gfp);
return ret;
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a847fc86ac32..d80ec43ac4e0 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -287,7 +287,10 @@ struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
root_cache->size, root_cache->align,
root_cache->flags, root_cache->ctor,
memcg, root_cache);
- if (IS_ERR(s))
+ if (!IS_ERR(s))
+ list_add(&s->memcg_params->siblings,
+ &root_cache->memcg_params->children);
+ else
s = NULL;
mutex_unlock(&slab_mutex);
@@ -300,17 +303,15 @@ struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
static int memcg_cleanup_cache_params(struct kmem_cache *s)
{
- int rc;
-
if (!s->memcg_params ||
!s->memcg_params->is_root_cache)
return 0;
mutex_unlock(&slab_mutex);
- rc = __memcg_cleanup_cache_params(s);
+ __memcg_cleanup_cache_params(s);
mutex_lock(&slab_mutex);
- return rc;
+ return !list_empty(&s->memcg_params->children);
}
#else
static int memcg_cleanup_cache_params(struct kmem_cache *s)
@@ -347,6 +348,10 @@ void kmem_cache_destroy(struct kmem_cache *s)
}
list_del(&s->list);
+#ifdef CONFIG_MEMCG_KMEM
+ if (!is_root_cache(s))
+ list_del(&s->memcg_params->siblings);
+#endif
mutex_unlock(&slab_mutex);
if (s->flags & SLAB_DESTROY_BY_RCU)
@@ -685,20 +690,17 @@ void slab_stop(struct seq_file *m, void *p)
static void
memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
{
- struct kmem_cache *c;
+#ifdef CONFIG_MEMCG_KMEM
+ struct memcg_cache_params *params;
struct slabinfo sinfo;
- int i;
- if (!is_root_cache(s))
+ if (!s->memcg_params ||
+ !s->memcg_params->is_root_cache)
return;
- for_each_memcg_cache_index(i) {
- c = cache_from_memcg_idx(s, i);
- if (!c)
- continue;
-
+ list_for_each_entry(params, &s->memcg_params->children, siblings) {
memset(&sinfo, 0, sizeof(sinfo));
- get_slabinfo(c, &sinfo);
+ get_slabinfo(params->cachep, &sinfo);
info->active_slabs += sinfo.active_slabs;
info->num_slabs += sinfo.num_slabs;
@@ -706,6 +708,7 @@ memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
info->active_objs += sinfo.active_objs;
info->num_objs += sinfo.num_objs;
}
+#endif
}
int cache_show(struct kmem_cache *s, struct seq_file *m)
diff --git a/mm/slub.c b/mm/slub.c
index a1cdbad02f0c..4114bebc0b2e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3690,6 +3690,23 @@ static struct kmem_cache *find_mergeable(size_t size, size_t align,
return NULL;
}
+static void memcg_slab_merge(struct kmem_cache *s, size_t size)
+{
+#ifdef CONFIG_MEMCG_KMEM
+ struct kmem_cache *c;
+ struct memcg_cache_params *params;
+
+ if (!s->memcg_params)
+ return;
+
+ list_for_each_entry(params, &s->memcg_params->children, siblings) {
+ c = params->cachep;
+ c->object_size = s->object_size;
+ c->inuse = max_t(int, c->inuse, ALIGN(size, sizeof(void *)));
+ }
+#endif
+}
+
struct kmem_cache *
__kmem_cache_alias(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
@@ -3698,9 +3715,6 @@ __kmem_cache_alias(const char *name, size_t size, size_t align,
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
- int i;
- struct kmem_cache *c;
-
s->refcount++;
/*
@@ -3710,14 +3724,7 @@ __kmem_cache_alias(const char *name, size_t size, size_t align,
s->object_size = max(s->object_size, (int)size);
s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
- for_each_memcg_cache_index(i) {
- c = cache_from_memcg_idx(s, i);
- if (!c)
- continue;
- c->object_size = s->object_size;
- c->inuse = max_t(int, c->inuse,
- ALIGN(size, sizeof(void *)));
- }
+ memcg_slab_merge(s, size);
if (sysfs_slab_alias(s, name)) {
s->refcount--;
@@ -4968,7 +4975,7 @@ static ssize_t slab_attr_store(struct kobject *kobj,
err = attribute->store(s, buf, len);
#ifdef CONFIG_MEMCG_KMEM
if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
- int i;
+ struct memcg_cache_params *params;
mutex_lock(&slab_mutex);
if (s->max_attr_size < len)
@@ -4991,10 +4998,10 @@ static ssize_t slab_attr_store(struct kobject *kobj,
* directly either failed or succeeded, in which case we loop
* through the descendants with best-effort propagation.
*/
- for_each_memcg_cache_index(i) {
- struct kmem_cache *c = cache_from_memcg_idx(s, i);
- if (c)
- attribute->store(c, buf, len);
+ if (s->memcg_params) {
+ list_for_each_entry(params,
+ &s->memcg_params->children, siblings)
+ attribute->store(params->cachep, buf, len);
}
mutex_unlock(&slab_mutex);
}
--
1.7.10.4
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