[PATCH v2 01/21] mm: list_lru: fix list_lru_count_one() return value
From: Muchun Song <hidden>
Date: 2021-05-27 06:24:28
Also in:
linux-fsdevel, linux-nfs, lkml
Subsystem:
memory management, shrinker, the rest · Maintainers:
Andrew Morton, Dave Chinner, Linus Torvalds
Since commit 2788cf0c401c ("memcg: reparent list_lrus and free kmemcg_id
on css offline"), the ->nr_items can be negative during memory cgroup
reparenting. In this case, list_lru_count_one() returns an unusual and
huge value. It can surprise users. So let it return zero when ->nr_items
is negative.
Signed-off-by: Muchun Song <redacted>
---
mm/list_lru.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/list_lru.c b/mm/list_lru.c
index cd58790d0fb3..4962d48d4410 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c@@ -176,13 +176,16 @@ unsigned long list_lru_count_one(struct list_lru *lru, { struct list_lru_node *nlru = &lru->node[nid]; struct list_lru_one *l; - unsigned long count; + long count; rcu_read_lock(); l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg)); count = READ_ONCE(l->nr_items); rcu_read_unlock(); + if (unlikely(count < 0)) + count = 0; + return count; } EXPORT_SYMBOL_GPL(list_lru_count_one);
--
2.11.0