@@ -3056,6 +3056,34 @@ static void memcg_free_cache_id(int id)
ida_simple_remove(&memcg_cache_ida, id);
}
+static inline void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
+ unsigned int nr_pages)
+{
+ rcu_read_lock();
+ __memcg_kmem_uncharge(obj_cgroup_memcg(objcg), nr_pages);
+ rcu_read_unlock();
+}
+
+static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
+ unsigned int nr_pages)
+{
+ struct mem_cgroup *memcg;
+ int ret;
+
+ rcu_read_lock();
+retry:
+ memcg = obj_cgroup_memcg(objcg);
+ if (unlikely(!css_tryget(&memcg->css)))
+ goto retry;
+ rcu_read_unlock();
+
+ ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
+
+ css_put(&memcg->css);
+
+ return ret;
+}
+
/**
* __memcg_kmem_charge: charge a number of kernel pages to a memcg
* @memcg: memory cgroup to charge
@@ -3180,11 +3208,8 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock)
unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
- if (nr_pages) {
- rcu_read_lock();
- __memcg_kmem_uncharge(obj_cgroup_memcg(old), nr_pages);
- rcu_read_unlock();
- }
+ if (nr_pages)
+ obj_cgroup_uncharge_pages(old, nr_pages);
/*
* The leftover is flushed to the centralized per-memcg value.
@@ -3242,7 +3267,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
{
- struct mem_cgroup *memcg;
unsigned int nr_pages, nr_bytes;
int ret;
@@ -3259,24 +3283,16 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
* refill_obj_stock(), called from this function or
* independently later.
*/
- rcu_read_lock();
-retry:
- memcg = obj_cgroup_memcg(objcg);
- if (unlikely(!css_tryget(&memcg->css)))
- goto retry;
- rcu_read_unlock();
-
nr_pages = size >> PAGE_SHIFT;
nr_bytes = size & (PAGE_SIZE - 1);
if (nr_bytes)
nr_pages += 1;
- ret = __memcg_kmem_charge(memcg, gfp, nr_pages);
+ ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
if (!ret && nr_bytes)
refill_obj_stock(objcg, PAGE_SIZE - nr_bytes);
- css_put(&memcg->css);
return ret;
}
We know that the unit of slab object charging is bytes, the unit of kmem page charging is PAGE_SIZE. If we want to reuse obj_cgroup APIs to charge the kmem pages, we should pass PAGE_SIZE (as third parameter) to obj_cgroup_charge(). Because the size is already PAGE_SIZE, we can skip touch the objcg stock. And obj_cgroup_{un}charge_pages() are introduced to charge in units of page level. In the later patch, we also can reuse those two helpers to charge or uncharge a number of kernel pages to a object cgroup. This is just a code movement without any functional changes. Signed-off-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> --- mm/memcontrol.c | 46 +++++++++++++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 15 deletions(-)