Commit d01dd17f authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
Browse files

memcg: use res_counter_uncharge_until() in move_parent() 



By using res_counter_uncharge_until(), we can avoid race and unnecessary
charging.

Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ying Han <yinghan@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Reviewed-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2bb2ba9d

mm/memcontrol.c

+36 −6
Original line number Diff line number Diff line
@@ -2422,6 +2422,24 @@ static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg, 
	}

}



/*

 * Cancel chrages in this cgroup....doesn't propagate to parent cgroup.

 * This is useful when moving usage to parent cgroup.

 */

static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,

					unsigned int nr_pages)

{

	unsigned long bytes = nr_pages * PAGE_SIZE;



	if (mem_cgroup_is_root(memcg))

		return;



	res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);

	if (do_swap_account)

		res_counter_uncharge_until(&memcg->memsw,

						memcg->memsw.parent, bytes);

}



/*

 * A helper function to get mem_cgroup from ID. must be called under

 * rcu_read_lock(). The caller must check css_is_removed() or some if
@@ -2680,16 +2698,28 @@ static int mem_cgroup_move_parent(struct page *page, 
	nr_pages = hpage_nr_pages(page);



	parent = mem_cgroup_from_cont(pcg);

	ret = __mem_cgroup_try_charge(NULL, gfp_mask, nr_pages, &parent, false);

	if (!parent->use_hierarchy) {

		ret = __mem_cgroup_try_charge(NULL,

					gfp_mask, nr_pages, &parent, false);

		if (ret)

			goto put_back;

	}



	if (nr_pages > 1)

		flags = compound_lock_irqsave(page);



	ret = mem_cgroup_move_account(page, nr_pages, pc, child, parent, true);

	if (parent->use_hierarchy) {

		ret = mem_cgroup_move_account(page, nr_pages,

					pc, child, parent, false);

		if (!ret)

			__mem_cgroup_cancel_local_charge(child, nr_pages);

	} else {

		ret = mem_cgroup_move_account(page, nr_pages,

					pc, child, parent, true);



		if (ret)

			__mem_cgroup_cancel_charge(parent, nr_pages);

	}



	if (nr_pages > 1)

		compound_unlock_irqrestore(page, flags);

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