Commit c41a40b6 authored by Muchun Song's avatar Muchun Song Committed by Linus Torvalds
Browse files

mm: memcontrol: replace the loop with a list_for_each_entry() 

The rule of list walk has gone since commit a9d5adee
("mm/memcontrol: allow to uncharge page without using page->lru field")

So remove the strange comment and replace the loop with a
list_for_each_entry().

There is only one caller of the uncharge_list().  So just fold it into
mem_cgroup_uncharge_list() and remove it.

Link: https://lkml.kernel.org/r/20210204163055.56080-1-songmuchun@bytedance.com


Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarRoman Gushchin <guro@fb.com>
Reviewed-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8a260162

mm/memcontrol.c

+8 −27
Original line number Diff line number Diff line
@@ -6862,31 +6862,6 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug) 
	css_put(&ug->memcg->css);

}



static void uncharge_list(struct list_head *page_list)

{

	struct uncharge_gather ug;

	struct list_head *next;



	uncharge_gather_clear(&ug);



	/*

	 * Note that the list can be a single page->lru; hence the

	 * do-while loop instead of a simple list_for_each_entry().

	 */

	next = page_list->next;

	do {

		struct page *page;



		page = list_entry(next, struct page, lru);

		next = page->lru.next;



		uncharge_page(page, &ug);

	} while (next != page_list);



	if (ug.memcg)

		uncharge_batch(&ug);

}



/**

 * mem_cgroup_uncharge - uncharge a page

 * @page: page to uncharge
@@ -6918,11 +6893,17 @@ void mem_cgroup_uncharge(struct page *page) 
 */

void mem_cgroup_uncharge_list(struct list_head *page_list)

{

	struct uncharge_gather ug;

	struct page *page;



	if (mem_cgroup_disabled())

		return;



	if (!list_empty(page_list))

		uncharge_list(page_list);

	uncharge_gather_clear(&ug);

	list_for_each_entry(page, page_list, lru)

		uncharge_page(page, &ug);

	if (ug.memcg)

		uncharge_batch(&ug);

}



/**