From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: memcontrol: introduce obj_cgroup_{un}charge_pages
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 latter 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.
Link: https://lkml.kernel.org/r/20210319163821.20704-3-songmuchun@xxxxxxxxxxxxx
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Acked-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 63 +++++++++++++++++++++++++++++-----------------
1 file changed, 40 insertions(+), 23 deletions(-)
--- a/mm/memcontrol.c~mm-memcontrol-introduce-obj_cgroup_uncharge_pages
+++ a/mm/memcontrol.c
@@ -2874,6 +2874,20 @@ static void commit_charge(struct page *p
page->memcg_data = (unsigned long)memcg;
}
+static struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg)
+{
+ struct mem_cgroup *memcg;
+
+ rcu_read_lock();
+retry:
+ memcg = obj_cgroup_memcg(objcg);
+ if (unlikely(!css_tryget(&memcg->css)))
+ goto retry;
+ rcu_read_unlock();
+
+ return memcg;
+}
+
#ifdef CONFIG_MEMCG_KMEM
int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s,
gfp_t gfp, bool new_page)
@@ -3025,6 +3039,29 @@ static void memcg_free_cache_id(int id)
ida_simple_remove(&memcg_cache_ida, id);
}
+static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
+ unsigned int nr_pages)
+{
+ struct mem_cgroup *memcg;
+
+ memcg = get_mem_cgroup_from_objcg(objcg);
+ __memcg_kmem_uncharge(memcg, nr_pages);
+ css_put(&memcg->css);
+}
+
+static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
+ unsigned int nr_pages)
+{
+ struct mem_cgroup *memcg;
+ int ret;
+
+ memcg = get_mem_cgroup_from_objcg(objcg);
+ 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
@@ -3149,19 +3186,8 @@ static void drain_obj_stock(struct memcg
unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
- if (nr_pages) {
- struct mem_cgroup *memcg;
-
- rcu_read_lock();
-retry:
- memcg = obj_cgroup_memcg(old);
- if (unlikely(!css_tryget(&memcg->css)))
- goto retry;
- rcu_read_unlock();
-
- __memcg_kmem_uncharge(memcg, nr_pages);
- css_put(&memcg->css);
- }
+ if (nr_pages)
+ obj_cgroup_uncharge_pages(old, nr_pages);
/*
* The leftover is flushed to the centralized per-memcg value.
@@ -3219,7 +3245,6 @@ static void refill_obj_stock(struct obj_
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;
@@ -3236,24 +3261,16 @@ int obj_cgroup_charge(struct obj_cgroup
* 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;
}
_
