The patch titled
Subject: memcg: increment static branch right after limit set
has been added to the -mm tree. Its filename is
memcg-increment-static-branch-right-after-limit-set.patch
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------------------------------------------------------
From: Glauber Costa <glommer@xxxxxxxxxxxxx>
Subject: memcg: increment static branch right after limit set
We were deferring the kmemcg static branch increment to a later time, due
to a nasty dependency between the cpu_hotplug lock, taken by the jump
label update, and the cgroup_lock.
Now we no longer take the cgroup lock, and we can save ourselves the
trouble.
Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 31 +++++++------------------------
1 file changed, 7 insertions(+), 24 deletions(-)
diff -puN mm/memcontrol.c~memcg-increment-static-branch-right-after-limit-set mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-increment-static-branch-right-after-limit-set
+++ a/mm/memcontrol.c
@@ -4972,8 +4972,6 @@ static int memcg_update_kmem_limit(struc
{
int ret = -EINVAL;
#ifdef CONFIG_MEMCG_KMEM
- bool must_inc_static_branch = false;
-
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
/*
* For simplicity, we won't allow this to be disabled. It also can't
@@ -5002,7 +5000,13 @@ static int memcg_update_kmem_limit(struc
res_counter_set_limit(&memcg->kmem, RESOURCE_MAX);
goto out;
}
- must_inc_static_branch = true;
+ static_key_slow_inc(&memcg_kmem_enabled_key);
+ /*
+ * setting the active bit after the inc will guarantee no one
+ * starts accounting before all call sites are patched
+ */
+ memcg_kmem_set_active(memcg);
+
/*
* kmem charges can outlive the cgroup. In the case of slab
* pages, for instance, a page contain objects from various
@@ -5015,27 +5019,6 @@ static int memcg_update_kmem_limit(struc
out:
mutex_unlock(&set_limit_mutex);
mutex_unlock(&memcg_create_mutex);
-
- /*
- * We are by now familiar with the fact that we can't inc the static
- * branch inside cgroup_lock. See disarm functions for details. A
- * worker here is overkill, but also wrong: After the limit is set, we
- * must start accounting right away. Since this operation can't fail,
- * we can safely defer it to here - no rollback will be needed.
- *
- * The boolean used to control this is also safe, because
- * KMEM_ACCOUNTED_ACTIVATED guarantees that only one process will be
- * able to set it to true;
- */
- if (must_inc_static_branch) {
- static_key_slow_inc(&memcg_kmem_enabled_key);
- /*
- * setting the active bit after the inc will guarantee no one
- * starts accounting before all call sites are patched
- */
- memcg_kmem_set_active(memcg);
- }
-
#endif
return ret;
}
_
Patches currently in -mm which might be from glommer@xxxxxxxxxxxxx are
memcg-fix-typo-in-kmemcg-cache-walk-macro.patch
memcgvmscan-do-not-break-out-targeted-reclaim-without-reclaimed-pages.patch
memcg-reduce-the-size-of-struct-memcg-244-fold.patch
memcg-reduce-the-size-of-struct-memcg-244-fold-fix.patch
memcg-prevent-changes-to-move_charge_at_immigrate-during-task-attach.patch
memcg-split-part-of-memcg-creation-to-css_online.patch
memcg-fast-hierarchy-aware-child-test.patch
memcg-fast-hierarchy-aware-child-test-fix.patch
memcg-replace-cgroup_lock-with-memcg-specific-memcg_lock.patch
memcg-increment-static-branch-right-after-limit-set.patch
memcg-avoid-dangling-reference-count-in-creation-failure.patch
memcg-debugging-facility-to-access-dangling-memcgs.patch
memcg-debugging-facility-to-access-dangling-memcgs-fix.patch
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