linux-kernel - [PATCH 07/18] mm: memcontrol: prepare move_account for removal of private page type counters

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Date:   Mon, 20 Apr 2020 18:11:15 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Joonsoo Kim <js1304@...il.com>,
        Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     Shakeel Butt <shakeelb@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        Michal Hocko <mhocko@...e.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Roman Gushchin <guro@...com>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com
Subject: [PATCH 07/18] mm: memcontrol: prepare move_account for removal of private page type counters

When memcg uses the generic vmstat counters, it doesn't need to do
anything at charging and uncharging time. It does, however, need to
migrate counts when pages move to a different cgroup in move_account.

Prepare the move_account function for the arrival of NR_FILE_PAGES,
NR_ANON_MAPPED, NR_ANON_THPS etc. by having a branch for files and a
branch for anon, which can then divided into sub-branches.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/memcontrol.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e3e8913a5b28..ac6f2b073a5a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5374,7 +5374,6 @@ static int mem_cgroup_move_account(struct page *page,
 	struct pglist_data *pgdat;
 	unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1;
 	int ret;
-	bool anon;
 
 	VM_BUG_ON(from == to);
 	VM_BUG_ON_PAGE(PageLRU(page), page);
@@ -5392,25 +5391,27 @@ static int mem_cgroup_move_account(struct page *page,
 	if (page->mem_cgroup != from)
 		goto out_unlock;
 
-	anon = PageAnon(page);
-
 	pgdat = page_pgdat(page);
 	from_vec = mem_cgroup_lruvec(from, pgdat);
 	to_vec = mem_cgroup_lruvec(to, pgdat);
 
 	lock_page_memcg(page);
 
-	if (!anon && page_mapped(page)) {
-		__mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
-		__mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
-	}
+	if (!PageAnon(page)) {
+		if (page_mapped(page)) {
+			__mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
+			__mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
+		}
 
-	if (!anon && PageDirty(page)) {
-		struct address_space *mapping = page_mapping(page);
+		if (PageDirty(page)) {
+			struct address_space *mapping = page_mapping(page);
 
-		if (mapping_cap_account_dirty(mapping)) {
-			__mod_lruvec_state(from_vec, NR_FILE_DIRTY, -nr_pages);
-			__mod_lruvec_state(to_vec, NR_FILE_DIRTY, nr_pages);
+			if (mapping_cap_account_dirty(mapping)) {
+				__mod_lruvec_state(from_vec, NR_FILE_DIRTY,
+						   -nr_pages);
+				__mod_lruvec_state(to_vec, NR_FILE_DIRTY,
+						   nr_pages);
+			}
 		}
 	}
 
-- 
2.26.0