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_page() 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 <[email protected]> --- mm/memcontrol.c | 46 +++++++++++++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 15 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 845eec01ef9d..faae16def127 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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_page(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_page(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_page(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_page(objcg, gfp, nr_pages); if (!ret && nr_bytes) refill_obj_stock(objcg, PAGE_SIZE - nr_bytes); - css_put(&memcg->css); return ret; } -- 2.11.0
