obj_cgroup_release is called when all the references to the objcg have
been released i.e. no more memory objects are pointing to it. Most
probably objcg->memcg will be pointing to some ancestor memcg. In
obj_cgroup_release(), the kernel calls obj_cgroup_uncharge_pages() which
refills the local stock.
There is no need to refill the local stock with some ancestor memcg and
flush the local stock. Let's decouple obj_cgroup_release() from the
local stock by uncharging instead of refilling. One additional benefit
of this change is that it removes the requirement to only call
obj_cgroup_put() outside of local_lock.
Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/memcontrol.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7054b0ebd207..83db180455a1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -129,8 +129,7 @@ bool mem_cgroup_kmem_disabled(void)
return cgroup_memory_nokmem;
}
-static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
- unsigned int nr_pages);
+static void memcg_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages);
static void obj_cgroup_release(struct percpu_ref *ref)
{
@@ -163,8 +162,16 @@ static void obj_cgroup_release(struct percpu_ref *ref)
WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1));
nr_pages = nr_bytes >> PAGE_SHIFT;
- if (nr_pages)
- obj_cgroup_uncharge_pages(objcg, nr_pages);
+ if (nr_pages) {
+ struct mem_cgroup *memcg;
+
+ memcg = get_mem_cgroup_from_objcg(objcg);
+ mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages);
+ memcg1_account_kmem(memcg, -nr_pages);
+ if (!mem_cgroup_is_root(memcg))
+ memcg_uncharge(memcg, nr_pages);
+ css_put(&memcg->css);
+ }
spin_lock_irqsave(&objcg_lock, flags);
list_del(&objcg->list);
--
2.47.1
