[PATCH 7/8] memcg: don't use css_id any more

[Li Zefan <lizefan@huawei.com>]

Now memcg uses cgroup->id instead of css_id. Update some comments and
set mem_cgroup_subsys->use_id to 0.

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 mm/memcontrol.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 947dff1..26ee672 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -574,16 +574,11 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
 #ifdef CONFIG_MEMCG_KMEM
 /*
  * This will be the memcg's index in each cache's ->memcg_params->memcg_caches.
- * There are two main reasons for not using the css_id for this:
- *  1) this works better in sparse environments, where we have a lot of memcgs,
- *     but only a few kmem-limited. Or also, if we have, for instance, 200
- *     memcgs, and none but the 200th is kmem-limited, we'd have to have a
- *     200 entry array for that.
- *
- *  2) In order not to violate the cgroup API, we would like to do all memory
- *     allocation in ->create(). At that point, we haven't yet allocated the
- *     css_id. Having a separate index prevents us from messing with the cgroup
- *     core for this
+ * The main reason for not using cgrp_id for this:
+ *  this works better in sparse environments, where we have a lot of memcgs,
+ *  but only a few kmem-limited. Or also, if we have, for instance, 200
+ *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
+ *  200 entry array for that.
  *
  * The current size of the caches array is stored in
  * memcg_limited_groups_array_size.  It will double each time we have to
@@ -598,10 +593,10 @@ int memcg_limited_groups_array_size;
  * cgroups is a reasonable guess. In the future, it could be a parameter or
  * tunable, but that is strictly not necessary.
  *
- * MAX_SIZE should be as large as the number of css_ids. Ideally, we could get
+ * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
  * this constant directly from cgroup, but it is understandable that this is
  * better kept as an internal representation in cgroup.c. In any case, the
- * css_id space is not getting any smaller, and we don't have to necessarily
+ * cgrp_id space is not getting any smaller, and we don't have to necessarily
  * increase ours as well if it increases.
  */
 #define MEMCG_CACHES_MIN_SIZE 4
@@ -6065,7 +6060,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
 	size_t size = memcg_size();
 
 	mem_cgroup_remove_from_trees(memcg);
-	free_css_id(&mem_cgroup_subsys, &memcg->css);
 
 	for_each_node(node)
 		free_mem_cgroup_per_zone_info(memcg, node);
@@ -6846,7 +6840,6 @@ struct cgroup_subsys mem_cgroup_subsys = {
 	.attach = mem_cgroup_move_task,
 	.base_cftypes = mem_cgroup_files,
 	.early_init = 0,
-	.use_id = 1,
 };
 
 #ifdef CONFIG_MEMCG_SWAP
-- 
1.8.0.2