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>
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@ -77,7 +77,8 @@ extern void mem_cgroup_uncharge_cache_page(struct page *page);
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bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
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bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
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struct mem_cgroup *memcg);
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struct mem_cgroup *memcg);
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int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg);
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bool task_in_mem_cgroup(struct task_struct *task,
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const struct mem_cgroup *memcg);
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extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
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extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
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extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
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extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
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@ -273,10 +274,10 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
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return true;
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return true;
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}
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}
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static inline int task_in_mem_cgroup(struct task_struct *task,
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static inline bool task_in_mem_cgroup(struct task_struct *task,
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const struct mem_cgroup *memcg)
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const struct mem_cgroup *memcg)
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{
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{
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return 1;
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return true;
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}
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}
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static inline struct cgroup_subsys_state
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static inline struct cgroup_subsys_state
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@ -1448,11 +1448,12 @@ static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
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return ret;
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return ret;
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}
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}
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int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
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bool task_in_mem_cgroup(struct task_struct *task,
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const struct mem_cgroup *memcg)
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{
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{
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int ret;
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struct mem_cgroup *curr = NULL;
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struct mem_cgroup *curr = NULL;
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struct task_struct *p;
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struct task_struct *p;
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bool ret;
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p = find_lock_task_mm(task);
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p = find_lock_task_mm(task);
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if (p) {
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if (p) {
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@ -1464,14 +1465,14 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
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* killer still needs to detect if they have already been oom
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* killer still needs to detect if they have already been oom
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* killed to prevent needlessly killing additional tasks.
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* killed to prevent needlessly killing additional tasks.
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*/
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*/
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task_lock(task);
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rcu_read_lock();
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curr = mem_cgroup_from_task(task);
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curr = mem_cgroup_from_task(task);
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if (curr)
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if (curr)
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css_get(&curr->css);
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css_get(&curr->css);
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task_unlock(task);
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rcu_read_unlock();
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}
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}
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if (!curr)
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if (!curr)
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return 0;
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return false;
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/*
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/*
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* We should check use_hierarchy of "memcg" not "curr". Because checking
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* We should check use_hierarchy of "memcg" not "curr". Because checking
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* use_hierarchy of "curr" here make this function true if hierarchy is
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* use_hierarchy of "curr" here make this function true if hierarchy is
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