+ mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch added to -mm tree

+ mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: memcontrol: replace the loop with a list_for_each_entry()
has been added to the -mm tree.  Its filename is
     mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch

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------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: memcontrol: replace the loop with a list_for_each_entry()

The rule of list walk has gone since:

 commit a9d5adeeb4b2 ("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>
---

 mm/memcontrol.c |   35 ++++++++---------------------------
 1 file changed, 8 insertions(+), 27 deletions(-)

--- a/mm/memcontrol.c~mm-memcontrol-replace-the-loop-with-a-list_for_each_entry
+++ a/mm/memcontrol.c
@@ -6862,31 +6862,6 @@ static void uncharge_page(struct page *p
 	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 *pa
  */
 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);
 }
 
 /**
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page.patch
mm-hugetlb-fix-a-race-between-freeing-and-dissolving-the-page.patch
mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch
mm-hugetlb-remove-vm_bug_on_page-from-page_huge_active.patch
mm-migrate-do-not-migrate-hugetlb-page-whose-refcount-is-one.patch
mm-hugetlb-fix-missing-put_page-in-gather_surplus_pages.patch
mm-memcontrol-optimize-per-lruvec-stats-counter-memory-usage.patch
mm-memcontrol-fix-nr_anon_thps-accounting-in-charge-moving.patch
mm-memcontrol-convert-nr_anon_thps-account-to-pages.patch
mm-memcontrol-convert-nr_file_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_pmdmapped-account-to-pages.patch
mm-memcontrol-convert-nr_file_pmdmapped-account-to-pages.patch
mm-memcontrol-make-the-slab-calculation-consistent.patch
mm-memcontrol-replace-the-loop-with-a-list_for_each_entry.patch
hugetlb-convert-page_huge_active-hpagemigratable-flag-fix.patch