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

The rule of list walk has gone since commit a9d5adeeb4
("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: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Muchun Song 2021-02-24 12:04:08 -08:00 committed by Linus Torvalds
parent 8a260162f9
commit c41a40b6ba
1 changed files with 8 additions and 27 deletions

View File

@ -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);
}
/**