slab: introduce __kmemcg_cache_deactivate()

__kmem_cache_shrink() is called with %true @deactivate only for memcg
caches.  Remove @deactivate from __kmem_cache_shrink() and introduce
__kmemcg_cache_deactivate() instead.  Each memcg-supporting allocator
should implement it and it should deactivate and drain the cache.

This is to allow memcg cache deactivation behavior to further deviate
from simple shrinking without messing up __kmem_cache_shrink().

This is pure reorganization and doesn't introduce any observable
behavior changes.

v2: Dropped unnecessary ifdef in mm/slab.h as suggested by Vladimir.

Link: http://lkml.kernel.org/r/20170117235411.9408-8-tj@kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 36 insertions, 23 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 8a0e3392f181..bd63450a9b16 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2315,7 +2315,7 @@ out:
         return nr_freed;
 }
 
-int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
+int __kmem_cache_shrink(struct kmem_cache *cachep)
 {
         int ret = 0;
         int node;
@@ -2333,9 +2333,16 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
         return (ret ? 1 : 0);
 }
 
+#ifdef CONFIG_MEMCG
+void __kmemcg_cache_deactivate(struct kmem_cache *cachep)
+{
+        __kmem_cache_shrink(cachep);
+}
+#endif
+
 int __kmem_cache_shutdown(struct kmem_cache *cachep)
 {
-        return __kmem_cache_shrink(cachep, false);
+        return __kmem_cache_shrink(cachep);
 }
 
 void __kmem_cache_release(struct kmem_cache *cachep)
diff --git a/mm/slab.h b/mm/slab.h
index 9631bb27c772..7bff1ee513c2 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -167,7 +167,8 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 
 int __kmem_cache_shutdown(struct kmem_cache *);
 void __kmem_cache_release(struct kmem_cache *);
-int __kmem_cache_shrink(struct kmem_cache *, bool);
+int __kmem_cache_shrink(struct kmem_cache *);
+void __kmemcg_cache_deactivate(struct kmem_cache *s);
 void slab_kmem_cache_release(struct kmem_cache *);
 
 struct seq_file;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 274697e1a42a..59e41bb81575 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -646,7 +646,7 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
                 if (!c)
                         continue;
 
-                __kmem_cache_shrink(c, true);
+                __kmemcg_cache_deactivate(c);
                 arr->entries[idx] = NULL;
         }
         mutex_unlock(&slab_mutex);
@@ -794,7 +794,7 @@ int kmem_cache_shrink(struct kmem_cache *cachep)
         get_online_cpus();
         get_online_mems();
         kasan_cache_shrink(cachep);
-        ret = __kmem_cache_shrink(cachep, false);
+        ret = __kmem_cache_shrink(cachep);
         put_online_mems();
         put_online_cpus();
         return ret;
diff --git a/mm/slob.c b/mm/slob.c
index 5ec158054ffe..eac04d4357ec 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -634,7 +634,7 @@ void __kmem_cache_release(struct kmem_cache *c)
 {
 }
 
-int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate)
+int __kmem_cache_shrink(struct kmem_cache *d)
 {
         return 0;
 }
diff --git a/mm/slub.c b/mm/slub.c
index 03b012bcb5fa..8a4591526f37 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3894,7 +3894,7 @@ EXPORT_SYMBOL(kfree);
  * being allocated from last increasing the chance that the last objects
  * are freed in them.
  */
-int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate)
+int __kmem_cache_shrink(struct kmem_cache *s)
 {
         int node;
         int i;
@@ -3906,21 +3906,6 @@ int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate)
         unsigned long flags;
         int ret = 0;
 
-        if (deactivate) {
-                /*
-                 * Disable empty slabs caching. Used to avoid pinning offline
-                 * memory cgroups by kmem pages that can be freed.
-                 */
-                s->cpu_partial = 0;
-                s->min_partial = 0;
-
-                /*
-                 * s->cpu_partial is checked locklessly (see put_cpu_partial),
-                 * so we have to make sure the change is visible.
-                 */
-                synchronize_sched();
-        }
-
         flush_all(s);
         for_each_kmem_cache_node(s, node, n) {
                 INIT_LIST_HEAD(&discard);
@@ -3971,13 +3956,33 @@ int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate)
         return ret;
 }
 
+#ifdef CONFIG_MEMCG
+void __kmemcg_cache_deactivate(struct kmem_cache *s)
+{
+        /*
+         * Disable empty slabs caching. Used to avoid pinning offline
+         * memory cgroups by kmem pages that can be freed.
+         */
+        s->cpu_partial = 0;
+        s->min_partial = 0;
+
+        /*
+         * s->cpu_partial is checked locklessly (see put_cpu_partial), so
+         * we have to make sure the change is visible.
+         */
+        synchronize_sched();
+
+        __kmem_cache_shrink(s);
+}
+#endif
+
 static int slab_mem_going_offline_callback(void *arg)
 {
         struct kmem_cache *s;
 
         mutex_lock(&slab_mutex);
         list_for_each_entry(s, &slab_caches, list)
-                __kmem_cache_shrink(s, false);
+                __kmem_cache_shrink(s);
         mutex_unlock(&slab_mutex);
 
         return 0;