[RFC 3/5] mm/memcontrol: do not scan anon pages if memsw limit is hit

[Jingxiang Zeng]

From: Zeng Jingxiang <linuszeng@xxxxxxxxxxx>

When memory recycling is triggered by the hard watermark of
memsw, anonymous pages do not want to be recycled any further.
This is consistent with the processing method of cgroup v2.

Signed-off-by: Zeng Jingxiang <linuszeng@xxxxxxxxxxx>
---
 mm/memcontrol.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c1171fb2bfd6..623ebf610946 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5072,14 +5072,21 @@ void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 
 long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 {
+	struct page_counter *pg_counter;
 	long nr_swap_pages = get_nr_swap_pages();
 
-	if (mem_cgroup_disabled() || do_memsw_account())
+	if (mem_cgroup_disabled())
 		return nr_swap_pages;
-	for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg))
+	for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
+		if (do_memsw_account())
+			pg_counter = &memcg->memsw;
+		else
+			pg_counter = &memcg->swap;
+
 		nr_swap_pages = min_t(long, nr_swap_pages,
-				      READ_ONCE(memcg->swap.max) -
-				      page_counter_read(&memcg->swap));
+				      READ_ONCE(pg_counter->max) -
+				      page_counter_read(pg_counter));
+	}
 	return nr_swap_pages;
 }
 
-- 
2.41.1