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| author |   Muchun Song <songmuchun@bytedance.com> | 2021-11-05 13:37:50 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-06 13:30:35 -0700 |
| commit | 41d17431df4aa7c57761e04f81c94fb3c3beedf4 (patch) | |
| tree | 5847dee7f7d5e734fbd7fb7c625c1100700707f6 /mm/list_lru.c | |
| parent | mm: list_lru: remove holding lru lock (diff) | |
| download | linux-dev-41d17431df4aa7c57761e04f81c94fb3c3beedf4.tar.xz linux-dev-41d17431df4aa7c57761e04f81c94fb3c3beedf4.zip | |
mm: list_lru: fix the return value of list_lru_count_one()
Since commit 2788cf0c401c ("memcg: reparent list_lrus and free kmemcg_id
on css offline"), ->nr_items can be negative during memory cgroup
reparenting. In this case, list_lru_count_one() will return an unusual
and huge value, which can surprise users. At least for now it hasn't
affected any users. But it is better to let list_lru_count_ont()
returns zero when ->nr_items is negative.
Link: https://lkml.kernel.org/r/20211025124910.56433-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/list_lru.c')
| -rw-r--r-- | mm/list_lru.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/list_lru.c b/mm/list_lru.c index 9a1f7df1afc9..7572f8e70b86 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); |