[PATCH v4 22/25] slab: slab-specific propagation changes.

[Glauber Costa <glommer@parallels.com>]

When a parent cache does tune_cpucache, we need to propagate that to the
children as well. For that, we unfortunately need to tap into the slab core.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
---
 mm/slab.c        |   28 +++++++++++++++++++++++++++-
 mm/slab_common.c |    1 +
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index 4951c81..c280dc6 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3874,7 +3874,7 @@ static void do_ccupdate_local(void *info)
 }
 
 /* Always called with the slab_mutex held */
-static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
+static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
 				int batchcount, int shared, gfp_t gfp)
 {
 	struct ccupdate_struct *new;
@@ -3917,6 +3917,32 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
 	return alloc_kmemlist(cachep, gfp);
 }
 
+static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
+				int batchcount, int shared, gfp_t gfp)
+{
+	int ret;
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	struct kmem_cache *c;
+	struct mem_cgroup_cache_params *p;
+#endif
+
+	ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	if (slab_state < FULL)
+		return ret;
+
+	if ((ret < 0) || (cachep->memcg_params.id == -1))
+		return ret;
+
+	list_for_each_entry(p, &cachep->memcg_params.sibling_list, sibling_list) {
+		c = container_of(p, struct kmem_cache, memcg_params);
+		/* return value determined by the parent cache only */
+		__do_tune_cpucache(c, limit, batchcount, shared, gfp);
+	}
+#endif
+	return ret;
+}
+
 /* Called with slab_mutex held always */
 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
 {
diff --git a/mm/slab_common.c b/mm/slab_common.c
index b424b28..a8557e8 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -155,6 +155,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
 	s->flags = flags;
 	s->align = calculate_alignment(flags, align, size);
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	s->memcg_params.id = -1; /* not registered yet */
 	s->memcg_params.memcg = memcg;
 	s->memcg_params.parent = parent_cache;
 #endif
-- 
1.7.10.2