From: Muchun Song songmuchun@bytedance.com
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@bytedance.com 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 Cc: Michal Hocko mhocko@kernel.org Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Xiongchun Duan duanxiongchun@bytedance.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Chen Huang chenhuang5@huawei.com --- mm/memcontrol.c | 63 +++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 23 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index abeaf5cede74..d45c2c97d9b8 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2888,6 +2888,20 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg) 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 /* * The allocated objcg pointers array is not accounted directly. @@ -3032,6 +3046,29 @@ 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 @@ -3156,19 +3193,8 @@ 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) { - 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. @@ -3226,7 +3252,6 @@ 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;
@@ -3243,24 +3268,16 @@ 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; }