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mm: workingset: use lruvec_page_state_local() to count lru pages

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Commit 7404bd37cf ("mm: workingset: use lruvec_lru_size() to get the
number of lru pages") switched count_shadow_nodes() to lruvec_lru_size(). 
With CONFIG_MEMCG enabled, lruvec_lru_size() reads mz->lru_zone_size,
which only the classic LRU paths maintain.  MGLRU accounts its pages
through __update_lru_size(), which skips that array, so with MGLRU on the
four evictable LRU lists are always seen as empty.  The shadow node budget
(pages >> 3) then collapses to slab plus unevictable pages, and the
workingset shadow shrinker reclaims eviction tokens almost as fast as they
are created, losing thrashing protection.

lruvec_page_state_local() reads lruvec_stats->state_local instead, which
both classic LRU and MGLRU maintain.  Switch back to it.  The reparenting
race this re-exposes on cgroup v2 is closed by the preceding patch that
redirects dying-memcg stat updates for all hierarchies.

Link: https://lore.kernel.org/2ed42f96aca124856ea30f774afb55cbe6d8ba58.1789096175.git.zhuhui@kylinos.cn
Fixes: 7404bd37cf ("mm: workingset: use lruvec_lru_size() to get the number of lru pages")
Signed-off-by: Hui Zhu <zhuhui@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: <stable@vger.kernel.org>
This commit is contained in:
Hui Zhu 2026-09-11 16:00:49 +08:00 committed by Andrew Morton
parent 7ee68fff2b
commit c7a37bac3c
1 changed files with 2 additions and 3 deletions
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5
mm/workingset.c
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@ -688,10 +688,9 @@ 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_lru_size(lruvec, i, MAX_NR_ZONES - 1);
pages += lruvec_page_state_local(lruvec,
NR_LRU_BASE + i);
pages += lruvec_page_state_local(
lruvec, NR_SLAB_RECLAIMABLE_B) >> PAGE_SHIFT;
pages += lruvec_page_state_local(