The patch titled
Subject: mm, memcg: don't take task_lock in task_in_mem_cgroup
has been added to the -mm tree. Its filename is
mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 9 +++++----
mm/memcontrol.c | 11 ++++++-----
2 files changed, 11 insertions(+), 9 deletions(-)
diff -puN include/linux/memcontrol.h~mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup
+++ a/include/linux/memcontrol.h
@@ -77,7 +77,8 @@ extern void mem_cgroup_uncharge_cache_pa
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(struc
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 -puN mm/memcontrol.c~mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup
+++ a/mm/memcontrol.c
@@ -1450,11 +1450,12 @@ static bool mem_cgroup_same_or_subtree(c
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) {
@@ -1466,14 +1467,14 @@ int task_in_mem_cgroup(struct task_struc
* 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
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
origin.patch
mm-memcg-dont-take-task_lock-in-task_in_mem_cgroup.patch
mm-dmapoolc-fix-null-dev-in-dma_pool_create.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
