mm: memcontrol: give the kmem states more descriptive names

On any given memcg, the kmem accounting feature has three separate
states: not initialized, structures allocated, and actively accounting
slab memory.  These are represented through a combination of the
kmem_acct_activated and kmem_acct_active flags, which is confusing.

Convert to a kmem_state enum with the states NONE, ALLOCATED, and
ONLINE.  Then rename the functions to modify the state accordingly.
This follows the nomenclature of css object states more closely.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 189f04d4d2ecc36c706299dd11ecbd58bd64e315..54dab4d43e6db0d0cb48032c1853b3471ea491a7 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -152,6 +152,12 @@ struct mem_cgroup_thresholds {
        struct mem_cgroup_threshold_ary *spare;
 };
 
+enum memcg_kmem_state {
+       KMEM_NONE,
+       KMEM_ALLOCATED,
+       KMEM_ONLINE,
+};
+
 /*
  * The memory controller data structure. The memory controller controls both
  * page cache and RSS per cgroup. We would eventually like to provide
@@ -233,8 +239,7 @@ struct mem_cgroup {
 #if defined(CONFIG_MEMCG_KMEM)
         /* Index in the kmem_cache->memcg_params.memcg_caches array */
        int kmemcg_id;
-       bool kmem_acct_activated;
-       bool kmem_acct_active;
+       enum memcg_kmem_state kmem_state;
 #endif
 
        int last_scanned_node;
@@ -750,9 +755,9 @@ static inline bool memcg_kmem_enabled(void)
        return static_branch_unlikely(&memcg_kmem_enabled_key);
 }
 
-static inline bool memcg_kmem_is_active(struct mem_cgroup *memcg)
+static inline bool memcg_kmem_online(struct mem_cgroup *memcg)
 {
-       return memcg->kmem_acct_active;
+       return memcg->kmem_state == KMEM_ONLINE;
 }
 
 /*
@@ -850,7 +855,7 @@ static inline bool memcg_kmem_enabled(void)
        return false;
 }
 
-static inline bool memcg_kmem_is_active(struct mem_cgroup *memcg)
+static inline bool memcg_kmem_online(struct mem_cgroup *memcg)
 {
        return false;
 }

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 71dced17b16deb2192ab8e1a36ccee3e997093de..24b6bded13f85603dda0ce95e0a0f5407cf2fc60 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2378,7 +2378,7 @@ int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
        struct page_counter *counter;
        int ret;
 
-       if (!memcg_kmem_is_active(memcg))
+       if (!memcg_kmem_online(memcg))
                return 0;
 
        if (!page_counter_try_charge(&memcg->kmem, nr_pages, &counter))
@@ -2861,14 +2861,13 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
 }
 
 #ifdef CONFIG_MEMCG_KMEM
-static int memcg_activate_kmem(struct mem_cgroup *memcg)
+static int memcg_online_kmem(struct mem_cgroup *memcg)
 {
        int err = 0;
        int memcg_id;
 
        BUG_ON(memcg->kmemcg_id >= 0);
-       BUG_ON(memcg->kmem_acct_activated);
-       BUG_ON(memcg->kmem_acct_active);
+       BUG_ON(memcg->kmem_state);
 
        /*
         * For simplicity, we won't allow this to be disabled.  It also can't
@@ -2898,14 +2897,13 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg)
 
        static_branch_inc(&memcg_kmem_enabled_key);
        /*
-        * A memory cgroup is considered kmem-active as soon as it gets
+        * A memory cgroup is considered kmem-online as soon as it gets
         * kmemcg_id. Setting the id after enabling static branching will
         * guarantee no one starts accounting before all call sites are
         * patched.
         */
        memcg->kmemcg_id = memcg_id;
-       memcg->kmem_acct_activated = true;
-       memcg->kmem_acct_active = true;
+       memcg->kmem_state = KMEM_ONLINE;
 out:
        return err;
 }
@@ -2917,8 +2915,8 @@ static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
 
        mutex_lock(&memcg_limit_mutex);
        /* Top-level cgroup doesn't propagate from root */
-       if (!memcg_kmem_is_active(memcg)) {
-               ret = memcg_activate_kmem(memcg);
+       if (!memcg_kmem_online(memcg)) {
+               ret = memcg_online_kmem(memcg);
                if (ret)
                        goto out;
        }
@@ -2938,11 +2936,12 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg)
 
        mutex_lock(&memcg_limit_mutex);
        /*
-        * If the parent cgroup is not kmem-active now, it cannot be activated
-        * after this point, because it has at least one child already.
+        * If the parent cgroup is not kmem-online now, it cannot be
+        * onlined after this point, because it has at least one child
+        * already.
         */
-       if (memcg_kmem_is_active(parent))
-               ret = memcg_activate_kmem(memcg);
+       if (memcg_kmem_online(parent))
+               ret = memcg_online_kmem(memcg);
        mutex_unlock(&memcg_limit_mutex);
        return ret;
 }
@@ -3590,22 +3589,21 @@ static int memcg_init_kmem(struct mem_cgroup *memcg)
        return tcp_init_cgroup(memcg);
 }
 
-static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
+static void memcg_offline_kmem(struct mem_cgroup *memcg)
 {
        struct cgroup_subsys_state *css;
        struct mem_cgroup *parent, *child;
        int kmemcg_id;
 
-       if (!memcg->kmem_acct_active)
+       if (memcg->kmem_state != KMEM_ONLINE)
                return;
-
        /*
-        * Clear the 'active' flag before clearing memcg_caches arrays entries.
-        * Since we take the slab_mutex in memcg_deactivate_kmem_caches(), it
-        * guarantees no cache will be created for this cgroup after we are
-        * done (see memcg_create_kmem_cache()).
+        * Clear the online state before clearing memcg_caches array
+        * entries. The slab_mutex in memcg_deactivate_kmem_caches()
+        * guarantees that no cache will be created for this cgroup
+        * after we are done (see memcg_create_kmem_cache()).
         */
-       memcg->kmem_acct_active = false;
+       memcg->kmem_state = KMEM_ALLOCATED;
 
        memcg_deactivate_kmem_caches(memcg);
 
@@ -3636,9 +3634,9 @@ static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
        memcg_free_cache_id(kmemcg_id);
 }
 
-static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+static void memcg_free_kmem(struct mem_cgroup *memcg)
 {
-       if (memcg->kmem_acct_activated) {
+       if (memcg->kmem_state == KMEM_ALLOCATED) {
                memcg_destroy_kmem_caches(memcg);
                static_branch_dec(&memcg_kmem_enabled_key);
                WARN_ON(page_counter_read(&memcg->kmem));
@@ -3651,11 +3649,11 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
        return 0;
 }
 
-static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
+static void memcg_offline_kmem(struct mem_cgroup *memcg)
 {
 }
 
-static void memcg_destroy_kmem(struct mem_cgroup *memcg)
+static void memcg_free_kmem(struct mem_cgroup *memcg)
 {
 }
 #endif
@@ -4308,7 +4306,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
 
        vmpressure_cleanup(&memcg->vmpressure);
 
-       memcg_deactivate_kmem(memcg);
+       memcg_offline_kmem(memcg);
 
        wb_memcg_offline(memcg);
 }
@@ -4324,7 +4322,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
 {
        struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
-       memcg_destroy_kmem(memcg);
+       memcg_free_kmem(memcg);
 #ifdef CONFIG_INET
        if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
                static_branch_dec(&memcg_sockets_enabled_key);

diff --git a/mm/slab_common.c b/mm/slab_common.c
index e016178063e19e86c21a46ea4a39ced03b0fe001..8c262e6dc33e132248a59a79f46b6c4bb62c5635 100644 (file)
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -503,10 +503,10 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
        mutex_lock(&slab_mutex);
 
        /*
-        * The memory cgroup could have been deactivated while the cache
+        * The memory cgroup could have been offlined while the cache
         * creation work was pending.
         */
-       if (!memcg_kmem_is_active(memcg))
+       if (!memcg_kmem_online(memcg))
                goto out_unlock;
 
        idx = memcg_cache_id(memcg);

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5ac86956ff9dc09d7dd2f16f02486756b7453320..05dd182f04fd5dcd9cedcb4633824299f9e27e4f 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -411,7 +411,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
        struct shrinker *shrinker;
        unsigned long freed = 0;
 
-       if (memcg && !memcg_kmem_is_active(memcg))
+       if (memcg && !memcg_kmem_online(memcg))
                return 0;
 
        if (nr_scanned == 0)