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dkim=pass header.d=bytedance-com.20150623.gappssmtp.com header.s=20150623 header.b="Q6/3D8pP"; spf=pass (imf13.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.215.182 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 99988E00080A X-Stat-Signature: yz6uwe4q4s9ijxa7b5xqbxnyrpbzxegn X-HE-Tag: 1622096654-669763 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 --- 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);