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From: Muchun Song <songmuchun@bytedance.com>
To: willy@infradead.org, akpm@linux-foundation.org,
	hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
	shakeelb@google.com, guro@fb.com, shy828301@gmail.com,
	alexs@kernel.org, richard.weiyang@gmail.com, david@fromorbit.com,
	trond.myklebust@hammerspace.com, anna.schumaker@netapp.com
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-nfs@vger.kernel.org,
	zhengqi.arch@bytedance.com, duanxiongchun@bytedance.com,
	fam.zheng@bytedance.com, Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH 01/17] mm: list_lru: fix list_lru_count_one() return value
Date: Tue, 11 May 2021 18:46:31 +0800	[thread overview]
Message-ID: <20210511104647.604-2-songmuchun@bytedance.com> (raw)
In-Reply-To: <20210511104647.604-1-songmuchun@bytedance.com>

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. Ii can surprise users. So let it return zero when ->nr_items
is negative.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 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


  reply	other threads:[~2021-05-11 10:51 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 10:46 [PATCH 00/17] Optimize list lru memory consumption Muchun Song
2021-05-11 10:46 ` Muchun Song [this message]
2021-05-11 10:46 ` [PATCH 02/17] mm: memcontrol: remove kmemcg_id reparenting Muchun Song
2021-05-11 10:46 ` [PATCH 03/17] mm: memcontrol: remove the kmem states Muchun Song
2021-05-11 10:46 ` [PATCH 04/17] mm: memcontrol: move memcg_online_kmem() to mem_cgroup_css_online() Muchun Song
2021-05-11 10:46 ` [PATCH 05/17] mm: list_lru: remove holding lru node lock Muchun Song
2021-05-11 10:46 ` [PATCH 06/17] mm: list_lru: only add the memcg aware lrus to the list Muchun Song
2021-05-11 10:46 ` [PATCH 07/17] mm: list_lru: optimize the array of per memcg lists Muchun Song
2021-05-11 10:46 ` [PATCH 08/17] mm: list_lru: remove memcg_aware from struct list_lru Muchun Song
2021-05-11 10:46 ` [PATCH 09/17] mm: introduce kmem_cache_alloc_lru Muchun Song
2021-05-11 10:46 ` [PATCH 10/17] fs: introduce alloc_inode_sb() to allocate filesystems specific inode Muchun Song
2021-05-11 23:40   ` Dave Chinner
2021-05-12  3:20     ` [External] " Muchun Song
2021-05-11 10:46 ` [PATCH 11/17] mm: dcache: use kmem_cache_alloc_lru() to allocate dentry Muchun Song
2021-05-11 10:46 ` [PATCH 12/17] xarray: replace kmem_cache_alloc with kmem_cache_alloc_lru Muchun Song
2021-05-11 10:46 ` [PATCH 13/17] mm: workingset: allocate list_lru on xa_node allocation Muchun Song
2021-05-11 10:46 ` [PATCH 14/17] nfs42: use a specific kmem_cache to allocate nfs4_xattr_entry Muchun Song
2021-05-11 10:46 ` [PATCH 15/17] mm: list_lru: allocate list_lru_one only when needed Muchun Song
2021-05-11 10:46 ` [PATCH 16/17] mm: list_lru: rename memcg_drain_all_list_lrus to memcg_reparent_list_lrus Muchun Song
2021-05-11 10:46 ` [PATCH 17/17] mm: list_lru: replace linear array with xarray Muchun Song

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