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authorDavid Rientjes <rientjes@google.com>2013-07-03 15:01:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:07:26 -0700
commitffbdccf5e1facd18b54429a749667fb185c10f20 (patch)
treeb3c8cf7399bb6493568d02bce307dce45b4ea9d7
parent541c237c0923f567c9c4cabb8a81635baadc713f (diff)
mm, memcg: don't take task_lock in task_in_mem_cgroup
For processes that have detached their mm's, task_in_mem_cgroup() unnecessarily takes task_lock() when rcu_read_lock() is all that is necessary to call mem_cgroup_from_task(). While we're here, switch task_in_mem_cgroup() to return bool. Signed-off-by: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/memcontrol.h9
-rw-r--r--mm/memcontrol.c11
2 files changed, 11 insertions, 9 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d6183f06d8c1..7b4d9d79570b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -77,7 +77,8 @@ extern void mem_cgroup_uncharge_cache_page(struct page *page);
bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
struct mem_cgroup *memcg);
-int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg);
+bool task_in_mem_cgroup(struct task_struct *task,
+ const struct mem_cgroup *memcg);
extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
@@ -273,10 +274,10 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
return true;
}
-static inline int task_in_mem_cgroup(struct task_struct *task,
- const struct mem_cgroup *memcg)
+static inline bool task_in_mem_cgroup(struct task_struct *task,
+ const struct mem_cgroup *memcg)
{
- return 1;
+ return true;
}
static inline struct cgroup_subsys_state
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 194721839cf5..4748966b1511 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1448,11 +1448,12 @@ static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
return ret;
}
-int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
+bool task_in_mem_cgroup(struct task_struct *task,
+ const struct mem_cgroup *memcg)
{
- int ret;
struct mem_cgroup *curr = NULL;
struct task_struct *p;
+ bool ret;
p = find_lock_task_mm(task);
if (p) {
@@ -1464,14 +1465,14 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
* killer still needs to detect if they have already been oom
* killed to prevent needlessly killing additional tasks.
*/
- task_lock(task);
+ rcu_read_lock();
curr = mem_cgroup_from_task(task);
if (curr)
css_get(&curr->css);
- task_unlock(task);
+ rcu_read_unlock();
}
if (!curr)
- return 0;
+ return false;
/*
* We should check use_hierarchy of "memcg" not "curr". Because checking
* use_hierarchy of "curr" here make this function true if hierarchy is