Christian Borntraeger reported a warning about "percpu ref
(obj_cgroup_release) <= 0 (-1) after switching to atomic".
Because we forgot to obtain the reference to the objcg and
wrongly obtain the reference of memcg.
Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 6 ++++++
mm/memcontrol.c | 6 +++++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0e8907957227..c960fd49c3e8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -804,6 +804,12 @@ static inline void obj_cgroup_get(struct obj_cgroup *objcg)
percpu_ref_get(&objcg->refcnt);
}
+static inline void obj_cgroup_get_many(struct obj_cgroup *objcg,
+ unsigned long nr)
+{
+ percpu_ref_get_many(&objcg->refcnt, nr);
+}
+
static inline void obj_cgroup_put(struct obj_cgroup *objcg)
{
percpu_ref_put(&objcg->refcnt);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c0b83a396299..64ada9e650a5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3133,7 +3133,11 @@ void split_page_memcg(struct page *head, unsigned int nr)
for (i = 1; i < nr; i++)
head[i].memcg_data = head->memcg_data;
- css_get_many(&memcg->css, nr - 1);
+
+ if (PageMemcgKmem(head))
+ obj_cgroup_get_many(__page_objcg(head), nr - 1);
+ else
+ css_get_many(&memcg->css, nr - 1);
}
#ifdef CONFIG_MEMCG_SWAP
--
2.11.0
