Merge branch 'akpm' (Andrew's patch-bomb)

Merge first batch of patches from Andrew Morton:
 "A few misc things and all the MM queue"

* emailed from Andrew Morton <akpm@linux-foundation.org>: (92 commits)
  memcg: avoid THP split in task migration
  thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE
  memcg: clean up existing move charge code
  mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read()
  mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event()
  mm/memcontrol.c: s/stealed/stolen/
  memcg: fix performance of mem_cgroup_begin_update_page_stat()
  memcg: remove PCG_FILE_MAPPED
  memcg: use new logic for page stat accounting
  memcg: remove PCG_MOVE_LOCK flag from page_cgroup
  memcg: simplify move_account() check
  memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat)
  memcg: kill dead prev_priority stubs
  memcg: remove PCG_CACHE page_cgroup flag
  memcg: let css_get_next() rely upon rcu_read_lock()
  cgroup: revert ss_id_lock to spinlock
  idr: make idr_get_next() good for rcu_read_lock()
  memcg: remove unnecessary thp check in page stat accounting
  memcg: remove redundant returns
  memcg: enum lru_list lru
  ...

1 files changed, 9 insertions, 10 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1ece8e20fdb5..f4ea4b6f3cf1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4881,9 +4881,9 @@ void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
 
         rcu_assign_pointer(id->css, NULL);
         rcu_assign_pointer(css->id, NULL);
-        write_lock(&ss->id_lock);
+        spin_lock(&ss->id_lock);
         idr_remove(&ss->idr, id->id);
-        write_unlock(&ss->id_lock);
+        spin_unlock(&ss->id_lock);
         kfree_rcu(id, rcu_head);
 }
 EXPORT_SYMBOL_GPL(free_css_id);
@@ -4909,10 +4909,10 @@ static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
                 error = -ENOMEM;
                 goto err_out;
         }
-        write_lock(&ss->id_lock);
+        spin_lock(&ss->id_lock);
         /* Don't use 0. allocates an ID of 1-65535 */
         error = idr_get_new_above(&ss->idr, newid, 1, &myid);
-        write_unlock(&ss->id_lock);
+        spin_unlock(&ss->id_lock);
 
         /* Returns error when there are no free spaces for new ID.*/
         if (error) {
@@ -4927,9 +4927,9 @@ static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
         return newid;
 remove_idr:
         error = -ENOSPC;
-        write_lock(&ss->id_lock);
+        spin_lock(&ss->id_lock);
         idr_remove(&ss->idr, myid);
-        write_unlock(&ss->id_lock);
+        spin_unlock(&ss->id_lock);
 err_out:
         kfree(newid);
         return ERR_PTR(error);
@@ -4941,7 +4941,7 @@ static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss,
 {
         struct css_id *newid;
 
-        rwlock_init(&ss->id_lock);
+        spin_lock_init(&ss->id_lock);
         idr_init(&ss->idr);
 
         newid = get_new_cssid(ss, 0);
@@ -5029,6 +5029,8 @@ css_get_next(struct cgroup_subsys *ss, int id,
                 return NULL;
 
         BUG_ON(!ss->use_id);
+        WARN_ON_ONCE(!rcu_read_lock_held());
+
         /* fill start point for scan */
         tmpid = id;
         while (1) {
@@ -5036,10 +5038,7 @@ css_get_next(struct cgroup_subsys *ss, int id,
                  * scan next entry from bitmap(tree), tmpid is updated after
                  * idr_get_next().
                  */
-                read_lock(&ss->id_lock);
                 tmp = idr_get_next(&ss->idr, &tmpid);
-                read_unlock(&ss->id_lock);
-
                 if (!tmp)
                         break;
                 if (tmp->depth >= depth && tmp->stack[depth] == rootid) {