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| author |   David Rientjes <rientjes@google.com> | 2013-07-03 15:01:23 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-03 16:07:26 -0700 |
| commit | ffbdccf5e1facd18b54429a749667fb185c10f20 (patch) | |
| tree | b3c8cf7399bb6493568d02bce307dce45b4ea9d7 | |
| parent | pagemap: prepare to reuse constant bits with page-shift (diff) | |
| download | linux-dev-ffbdccf5e1facd18b54429a749667fb185c10f20.tar.xz linux-dev-ffbdccf5e1facd18b54429a749667fb185c10f20.zip | |
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.h | 9 | ||||
| -rw-r--r-- | mm/memcontrol.c | 11 |
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 |