[PATCH v2 4/5] mm: memcg: charge memcg percpu memory to the parent cgroup

[Roman Gushchin <guro@xxxxxx>]

Memory cgroups are using large chunks of percpu memory to store
vmstat data. Yet this memory is not accounted at all, so in the
case when there are many (dying) cgroups, it's not exactly clear
where all the memory is.

Because the size of  memory cgroup internal structures can
dramatically exceed the size of object or page which is pinning
it in the memory, it's not a good idea to simple ignore it.
It actually breaks the isolation between cgroups.

Let's account the consumed percpu memory to the parent cgroup.

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
 mm/memcontrol.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 839b4d890a90..638ad499a9e0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5069,13 +5069,15 @@ static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
 	if (!pn)
 		return 1;
 
-	pn->lruvec_stat_local = alloc_percpu(struct lruvec_stat);
+	pn->lruvec_stat_local = alloc_percpu_gfp(struct lruvec_stat,
+						 GFP_KERNEL_ACCOUNT);
 	if (!pn->lruvec_stat_local) {
 		kfree(pn);
 		return 1;
 	}
 
-	pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat);
+	pn->lruvec_stat_cpu = alloc_percpu_gfp(struct lruvec_stat,
+					       GFP_KERNEL_ACCOUNT);
 	if (!pn->lruvec_stat_cpu) {
 		free_percpu(pn->lruvec_stat_local);
 		kfree(pn);
@@ -5149,11 +5151,13 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 		goto fail;
 	}
 
-	memcg->vmstats_local = alloc_percpu(struct memcg_vmstats_percpu);
+	memcg->vmstats_local = alloc_percpu_gfp(struct memcg_vmstats_percpu,
+						GFP_KERNEL_ACCOUNT);
 	if (!memcg->vmstats_local)
 		goto fail;
 
-	memcg->vmstats_percpu = alloc_percpu(struct memcg_vmstats_percpu);
+	memcg->vmstats_percpu = alloc_percpu_gfp(struct memcg_vmstats_percpu,
+						 GFP_KERNEL_ACCOUNT);
 	if (!memcg->vmstats_percpu)
 		goto fail;
 
@@ -5202,7 +5206,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 	struct mem_cgroup *memcg;
 	long error = -ENOMEM;
 
+	memalloc_use_memcg(parent);
 	memcg = mem_cgroup_alloc();
+	memalloc_unuse_memcg();
 	if (IS_ERR(memcg))
 		return ERR_CAST(memcg);
 
-- 
2.25.4