memcg: remove memcg->reclaim_param_lock
Johannes Weiner [Wed, 23 Mar 2011 23:42:32 +0000 (16:42 -0700)]
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>

mm/memcontrol.c

index b35a28d..8f93819 100644 (file)
@@ -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)