1 files changed, 5 insertions, 18 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0f711c213d2e..8a79a6f0f029 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -811,12 +811,10 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
          * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
          * hierarchy(even if use_hierarchy is disabled in "mem").
          */
-        rcu_read_lock();
         if (mem->use_hierarchy)
                 ret = css_is_ancestor(&curr->css, &mem->css);
         else
                 ret = (curr == mem);
-        rcu_read_unlock();
         css_put(&curr->css);
         return ret;
 }
@@ -1603,7 +1601,6 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                          * There is a small race that "from" or "to" can be
                          * freed by rmdir, so we use css_tryget().
                          */
-                        rcu_read_lock();
                         from = mc.from;
                         to = mc.to;
                         if (from && css_tryget(&from->css)) {
@@ -1624,7 +1621,6 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                                         do_continue = (to == mem_over_limit);
                                 css_put(&to->css);
                         }
-                        rcu_read_unlock();
                         if (do_continue) {
                                 DEFINE_WAIT(wait);
                                 prepare_to_wait(&mc.waitq, &wait,
@@ -2314,9 +2310,7 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 
         /* record memcg information */
         if (do_swap_account && swapout && memcg) {
-                rcu_read_lock();
                 swap_cgroup_record(ent, css_id(&memcg->css));
-                rcu_read_unlock();
                 mem_cgroup_get(memcg);
         }
         if (swapout && memcg)
@@ -2373,10 +2367,8 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
 {
         unsigned short old_id, new_id;
 
-        rcu_read_lock();
         old_id = css_id(&from->css);
         new_id = css_id(&to->css);
-        rcu_read_unlock();
 
         if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
                 mem_cgroup_swap_statistics(from, false);
@@ -4044,16 +4036,11 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
                         put_page(page);
         }
         /* throught */
-        if (ent.val && do_swap_account && !ret) {
-                unsigned short id;
-                rcu_read_lock();
-                id = css_id(&mc.from->css);
-                rcu_read_unlock();
-                if (id == lookup_swap_cgroup(ent)) {
-                        ret = MC_TARGET_SWAP;
-                        if (target)
-                                target->ent = ent;
-                }
+        if (ent.val && do_swap_account && !ret &&
+                        css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
+                ret = MC_TARGET_SWAP;
+                if (target)
+                        target->ent = ent;
         }
         return ret;
 }