Commit e3f73e77 authored by Muchun Song's avatar Muchun Song Committed by Zheng Zengkai
Browse files

mm: memcontrol: introduce obj_cgroup_{un}charge_pages 

mainline inclusion
from mainline-v5.13-rc1
commit e74d2259
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4C0GB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e74d225910ec3a9999f06934afa068b6a30babf8

----------------------------------------------------------------------

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: default avatarMuchun Song <songmuchun@bytedance.com>
Acked-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarShakeel 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarChen Huang <chenhuang5@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: default avatarChen Wandun <chenwandun@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 492cf0b0

mm/memcontrol.c

+40 −23
Original line number Diff line number Diff line
@@ -2844,6 +2844,20 @@ 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.
@@ -2988,6 +3002,29 @@ 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
@@ -3112,19 +3149,8 @@ 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.
@@ -3182,7 +3208,6 @@ 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;
@@ -3199,24 +3224,16 @@ 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;

}