[PATCH 7/9] slab: introduce __kmemcg_cache_deactivate()

Tejun Heo
2017-01-14T05:54:47Z

__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.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: 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>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/slab.c | 11 +++++++++--
mm/slab.h | 5 ++++-
mm/slab_common.c | 4 ++--
mm/slob.c | 2 +-
mm/slub.c | 39 ++++++++++++++++++++++-----------------
5 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 767e8e4..65814f2 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2314,7 +2314,7 @@ static int drain_freelist(struct kmem_cache *cache,
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;
@@ -2332,9 +2332,16 @@ 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 8f47a44..73ed6b5 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -164,7 +164,10 @@ 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 *);
+#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
+void __kmemcg_cache_deactivate(struct kmem_cache *s);
+#endif
void slab_kmem_cache_release(struct kmem_cache *);

struct seq_file;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index c0d0126..87e5535 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -602,7 +602,7 @@ 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);
@@ -727,7 +727,7 @@ 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 5ec1580..eac04d4 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 a26cb90..ef89a07 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3886,7 +3886,7 @@ 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;
@@ -3898,21 +3898,6 @@ 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);
@@ -3963,13 +3948,33 @@ 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;
--
2.9.3