On the default hierarchy, all memory consumption will be accounted
together and controlled by the same set of limits. Enable kmemcg on
the default hierarchy by default. Boot parameter "disable_kmemcg" can
be specified to turn it off.
v2: - v1 triggered oops on nested cgroup creations. Moved enabling
mechanism to memcg_propagate_kmem().
- Bypass busy test on kmem activation as it's unnecessary and gets
confused by controller being enabled on a cgroup which already
has processes.
- "disable_kmemcg" boot param added.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
mm/memcontrol.c | 43 ++++++++++++++++++++++++++++++-------------
1 file changed, 30 insertions(+), 13 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -346,6 +346,17 @@ EXPORT_SYMBOL(tcp_proto_cgroup);
#endif
#ifdef CONFIG_MEMCG_KMEM
+
+static bool kmemcg_disabled;
+
+static int __init disable_kmemcg(char *s)
+{
+ kmemcg_disabled = true;
+ pr_info("memcg: kernel memory support disabled on cgroup2");
+ return 0;
+}
+__setup("disable_kmemcg", disable_kmemcg);
+
/*
* This will be the memcg's index in each cache's ->memcg_params.memcg_caches.
* The main reason for not using cgroup id for this:
@@ -2908,9 +2919,9 @@ static int memcg_activate_kmem(struct me
BUG_ON(memcg->kmem_acct_active);
/*
- * For simplicity, we won't allow this to be disabled. It also can't
- * be changed if the cgroup has children already, or if tasks had
- * already joined.
+ * On traditional hierarchies, for simplicity, we won't allow this
+ * to be disabled. It also can't be changed if the cgroup has
+ * children already, or if tasks had already joined.
*
* If tasks join before we set the limit, a person looking at
* kmem.usage_in_bytes will have no way to determine when it took
@@ -2919,13 +2930,15 @@ static int memcg_activate_kmem(struct me
* After it first became limited, changes in the value of the limit are
* of course permitted.
*/
- mutex_lock(&memcg_create_mutex);
- if (cgroup_has_tasks(memcg->css.cgroup) ||
- (memcg->use_hierarchy && memcg_has_children(memcg)))
- err = -EBUSY;
- mutex_unlock(&memcg_create_mutex);
- if (err)
- goto out;
+ if (!cgroup_on_dfl(memcg->css.cgroup)) {
+ mutex_lock(&memcg_create_mutex);
+ if (cgroup_has_tasks(memcg->css.cgroup) ||
+ (memcg->use_hierarchy && memcg_has_children(memcg)))
+ err = -EBUSY;
+ mutex_unlock(&memcg_create_mutex);
+ if (err)
+ goto out;
+ }
memcg_id = memcg_alloc_cache_id();
if (memcg_id < 0) {
@@ -2978,10 +2991,14 @@ static int memcg_propagate_kmem(struct m
mutex_lock(&memcg_limit_mutex);
/*
- * If the parent cgroup is not kmem-active now, it cannot be activated
- * after this point, because it has at least one child already.
+ * On the default hierarchy, automatically enable kmemcg unless
+ * explicitly disabled by the boot param. On traditional
+ * hierarchies, inherit from the parent. If the parent cgroup is
+ * not kmem-active now, it cannot be activated after this point,
+ * because it has at least one child already.
*/
- if (memcg_kmem_is_active(parent))
+ if ((!kmemcg_disabled && cgroup_on_dfl(memcg->css.cgroup)) ||
+ memcg_kmem_is_active(parent))
ret = memcg_activate_kmem(memcg, PAGE_COUNTER_MAX);
mutex_unlock(&memcg_limit_mutex);
return ret;
--
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