mm: workingset: use lruvec_lru_size() to get the number of lru pages

For cgroup v2, count_shadow_nodes() is the only place to read
non-hierarchical stats (lruvec_stats->state_local).  To avoid the need to
consider cgroup v2 during subsequent non-hierarchical stats reparenting,
use lruvec_lru_size() instead of lruvec_page_state_local() to get the
number of lru pages.

For NR_SLAB_RECLAIMABLE_B and NR_SLAB_UNRECLAIMABLE_B cases, it appears
that the statistics here have already been problematic for a while since
slab pages have been reparented.  So just ignore it for now.

Link: https://lore.kernel.org/b1d448c667a8fb377c3390d9aba43bdb7e4d5739.1772711148.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yosry Ahmed <yosry@kernel.org>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 5 insertions, 4 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index d653fe050b8f..7a09df6977a5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -352,6 +352,7 @@ extern void swap_setup(void);
 extern unsigned long zone_reclaimable_pages(struct zone *zone);
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 					gfp_t gfp_mask, nodemask_t *mask);
+unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
 
 #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
 #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8472aa4bddd5..1ac4f959ec1c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -390,8 +390,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
  * @lru: lru to use
  * @zone_idx: zones to consider (use MAX_NR_ZONES - 1 for the whole LRU list)
  */
-static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
-				     int zone_idx)
+unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
 {
 	unsigned long size = 0;
 	int zid;
diff --git a/mm/workingset.c b/mm/workingset.c
index 95d722a452e1..07e6836d0502 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -691,9 +691,10 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 
 		mem_cgroup_flush_stats_ratelimited(sc->memcg);
 		lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
+
 		for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
-			pages += lruvec_page_state_local(lruvec,
-							 NR_LRU_BASE + i);
+			pages += lruvec_lru_size(lruvec, i, MAX_NR_ZONES - 1);
+
 		pages += lruvec_page_state_local(
 			lruvec, NR_SLAB_RECLAIMABLE_B) >> PAGE_SHIFT;
 		pages += lruvec_page_state_local(