memcg: remove memcg->reclaim_param_lock

The reclaim_param_lock is only taken around single reads and writes to
integer variables and is thus superfluous.  Drop it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 17 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b35a28d80ab5..8f9381976c59 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -218,12 +218,6 @@ struct mem_cgroup {
          * per zone LRU lists.
          */
         struct mem_cgroup_lru_info info;
-
-        /*
-          protect against reclaim related member.
-        */
-        spinlock_t reclaim_param_lock;
-
         /*
          * While reclaiming in a hierarchy, we cache the last child we
          * reclaimed from.
@@ -1130,17 +1124,12 @@ static unsigned long long mem_cgroup_margin(struct mem_cgroup *mem)
 static unsigned int get_swappiness(struct mem_cgroup *memcg)
 {
         struct cgroup *cgrp = memcg->css.cgroup;
-        unsigned int swappiness;
 
         /* root ? */
         if (cgrp->parent == NULL)
                 return vm_swappiness;
 
-        spin_lock(&memcg->reclaim_param_lock);
-        swappiness = memcg->swappiness;
-        spin_unlock(&memcg->reclaim_param_lock);
-
-        return swappiness;
+        return memcg->swappiness;
 }
 
 static void mem_cgroup_start_move(struct mem_cgroup *mem)
@@ -1356,13 +1345,11 @@ mem_cgroup_select_victim(struct mem_cgroup *root_mem)
 
                 rcu_read_unlock();
                 /* Updates scanning parameter */
-                spin_lock(&root_mem->reclaim_param_lock);
                 if (!css) {
                         /* this means start scan from ID:1 */
                         root_mem->last_scanned_child = 0;
                 } else
                         root_mem->last_scanned_child = found;
-                spin_unlock(&root_mem->reclaim_param_lock);
         }
 
         return ret;
@@ -3868,9 +3855,7 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
                 return -EINVAL;
         }
 
-        spin_lock(&memcg->reclaim_param_lock);
         memcg->swappiness = val;
-        spin_unlock(&memcg->reclaim_param_lock);
 
         cgroup_unlock();
 
@@ -4526,7 +4511,6 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
                 res_counter_init(&mem->memsw, NULL);
         }
         mem->last_scanned_child = 0;
-        spin_lock_init(&mem->reclaim_param_lock);
         INIT_LIST_HEAD(&mem->oom_notify);
 
         if (parent)