[PATCH 22/23] memcg: Per-memcg memory.kmem.slabinfo file.

[Glauber Costa <glommer@parallels.com>]

From: Suleiman Souhlal <ssouhlal@FreeBSD.org>

This file shows all the kmem_caches used by a memcg.

Signed-off-by: Suleiman Souhlal <suleiman@google.com>
---
 include/linux/slab.h |    1 +
 mm/memcontrol.c      |   17 ++++++++++
 mm/slab.c            |   88 +++++++++++++++++++++++++++++++++++++-------------
 mm/slub.c            |    5 +++
 4 files changed, 88 insertions(+), 23 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0dc49fa..6932205 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -327,6 +327,7 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 extern struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
 					 struct kmem_cache *cachep);
 void kmem_cache_drop_ref(struct kmem_cache *cachep);
+int mem_cgroup_slabinfo(struct mem_cgroup *mem, struct seq_file *m);
 #else
 #define MAX_KMEM_CACHE_TYPES 0
 #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 547b632..46ebd11 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5092,6 +5092,19 @@ static int mem_control_numa_stat_open(struct inode *unused, struct file *file)
 #endif /* CONFIG_NUMA */
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+static int mem_cgroup_slabinfo_show(struct cgroup *cgroup, struct cftype *ctf,
+				    struct seq_file *m)
+{
+	struct mem_cgroup *mem;
+
+	mem  = mem_cgroup_from_cont(cgroup);
+
+	if (mem == root_mem_cgroup)
+		mem = NULL;
+
+	return mem_cgroup_slabinfo(mem, m);
+}
+
 static struct cftype kmem_cgroup_files[] = {
 	{
 		.name = "kmem.limit_in_bytes",
@@ -5116,6 +5129,10 @@ static struct cftype kmem_cgroup_files[] = {
 		.trigger = mem_cgroup_reset,
 		.read = mem_cgroup_read,
 	},
+	{
+		.name = "kmem.slabinfo",
+		.read_seq_string = mem_cgroup_slabinfo_show,
+	},
 	{},
 };
 
diff --git a/mm/slab.c b/mm/slab.c
index 86f2275..3e13fef 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4518,21 +4519,26 @@ static void s_stop(struct seq_file *m, void *p)
 	mutex_unlock(&cache_chain_mutex);
 }
 
-static int s_show(struct seq_file *m, void *p)
-{
-	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, next);
-	struct slab *slabp;
+struct slab_counts {
 	unsigned long active_objs;
+	unsigned long active_slabs;
+	unsigned long num_slabs;
+	unsigned long free_objects;
+	unsigned long shared_avail;
 	unsigned long num_objs;
-	unsigned long active_slabs = 0;
-	unsigned long num_slabs, free_objects = 0, shared_avail = 0;
-	const char *name;
-	char *error = NULL;
-	int node;
+};
+
+static char *
+get_slab_counts(struct kmem_cache *cachep, struct slab_counts *c)
+{
 	struct kmem_list3 *l3;
+	struct slab *slabp;
+	char *error;
+	int node;
+
+	error = NULL;
+	memset(c, 0, sizeof(struct slab_counts));
 
-	active_objs = 0;
-	num_slabs = 0;
 	for_each_online_node(node) {
 		l3 = cachep->nodelists[node];
 		if (!l3)
@@ -4544,31 +4550,43 @@ static int s_show(struct seq_file *m, void *p)
 		list_for_each_entry(slabp, &l3->slabs_full, list) {
 			if (slabp->inuse != cachep->num && !error)
 				error = "slabs_full accounting error";
-			active_objs += cachep->num;
-			active_slabs++;
+			c->active_objs += cachep->num;
+			c->active_slabs++;
 		}
 		list_for_each_entry(slabp, &l3->slabs_partial, list) {
 			if (slabp->inuse == cachep->num && !error)
 				error = "slabs_partial inuse accounting error";
 			if (!slabp->inuse && !error)
 				error = "slabs_partial/inuse accounting error";
-			active_objs += slabp->inuse;
-			active_slabs++;
+			c->active_objs += slabp->inuse;
+			c->active_slabs++;
 		}
 		list_for_each_entry(slabp, &l3->slabs_free, list) {
 			if (slabp->inuse && !error)
 				error = "slabs_free/inuse accounting error";
-			num_slabs++;
+			c->num_slabs++;
 		}
-		free_objects += l3->free_objects;
+		c->free_objects += l3->free_objects;
 		if (l3->shared)
-			shared_avail += l3->shared->avail;
+			c->shared_avail += l3->shared->avail;
 
 		spin_unlock_irq(&l3->list_lock);
 	}
-	num_slabs += active_slabs;
-	num_objs = num_slabs * cachep->num;
-	if (num_objs - active_objs != free_objects && !error)
+	c->num_slabs += c->active_slabs;
+	c->num_objs = c->num_slabs * cachep->num;
+
+	return error;
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, next);
+	struct slab_counts c;
+	const char *name;
+	char *error;
+
+	error = get_slab_counts(cachep, &c);
+	if (c.num_objs - c.active_objs != c.free_objects && !error)
 		error = "free_objects accounting error";
 
 	name = cachep->name;
@@ -4576,12 +4594,12 @@ static int s_show(struct seq_file *m, void *p)
 		printk(KERN_ERR "slab: cache %s error: %s\n", name, error);
 
 	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
-		   name, active_objs, num_objs, cachep->buffer_size,
+		   name, c.active_objs, c.num_objs, cachep->buffer_size,
 		   cachep->num, (1 << cachep->gfporder));
 	seq_printf(m, " : tunables %4u %4u %4u",
 		   cachep->limit, cachep->batchcount, cachep->shared);
 	seq_printf(m, " : slabdata %6lu %6lu %6lu",
-		   active_slabs, num_slabs, shared_avail);
+		   c.active_slabs, c.num_slabs, c.shared_avail);
 #if STATS
 	{			/* list3 stats */
 		unsigned long high = cachep->high_mark;
@@ -4615,6 +4633,30 @@ static int s_show(struct seq_file *m, void *p)
 	return 0;
 }
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+int mem_cgroup_slabinfo(struct mem_cgroup *memcg, struct seq_file *m)
+{
+	struct kmem_cache *cachep;
+	struct slab_counts c;
+
+	seq_printf(m, "# name            <active_objs> <num_objs> <objsize>\n");
+
+	mutex_lock(&cache_chain_mutex);
+	list_for_each_entry(cachep, &cache_chain, next) {
+		if (cachep->memcg_params.memcg != memcg)
+			continue;
+
+		get_slab_counts(cachep, &c);
+
+		seq_printf(m, "%-17s %6lu %6lu %6u\n", cachep->name,
+		   c.active_objs, c.num_objs, cachep->buffer_size);
+	}
+	mutex_unlock(&cache_chain_mutex);
+
+	return 0;
+}
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
+
 /*
  * slabinfo_op - iterator that generates /proc/slabinfo
  *
diff --git a/mm/slub.c b/mm/slub.c
index 9b22139..1031d4d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4147,6 +4147,11 @@ void kmem_cache_drop_ref(struct kmem_cache *s)
 	BUG_ON(s->memcg_params.id != -1);
 	kmem_cache_destroy(s);
 }
+
+int mem_cgroup_slabinfo(struct mem_cgroup *memcg, struct seq_file *m)
+{
+	return 0;
+}
 #endif
 
 #ifdef CONFIG_SMP
-- 
1.7.7.6