The mem_cgroup_from_slab_obj() is supposed to be called under rcu lock or cgroup_mutex or others which could prevent returned memcg from being freed. Fix it by adding missing rcu read lock.
Fixes: 0a97c01cd20b ("list_lru: allow explicit memcg and NUMA node selection") Signed-off-by: Muchun Song songmuchun@bytedance.com Acked-by: Shakeel Butt shakeel.butt@linux.dev Cc: stable@vger.kernel.org --- v2: Only grab rcu lock when necessary (Vlastimil Babka)
mm/list_lru.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/mm/list_lru.c b/mm/list_lru.c index a29d96929d7c7..9b7ff06e9d326 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -85,6 +85,7 @@ list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx) } #endif /* CONFIG_MEMCG */
+/* The caller must ensure the memcg lifetime. */ bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, struct mem_cgroup *memcg) { @@ -109,14 +110,22 @@ EXPORT_SYMBOL_GPL(list_lru_add);
bool list_lru_add_obj(struct list_lru *lru, struct list_head *item) { + bool ret; int nid = page_to_nid(virt_to_page(item)); - struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? - mem_cgroup_from_slab_obj(item) : NULL;
- return list_lru_add(lru, item, nid, memcg); + if (list_lru_memcg_aware(lru)) { + rcu_read_lock(); + ret = list_lru_add(lru, item, nid, mem_cgroup_from_slab_obj(item)); + rcu_read_unlock(); + } else { + ret = list_lru_add(lru, item, nid, NULL); + } + + return ret; } EXPORT_SYMBOL_GPL(list_lru_add_obj);
+/* The caller must ensure the memcg lifetime. */ bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid, struct mem_cgroup *memcg) { @@ -139,11 +148,18 @@ EXPORT_SYMBOL_GPL(list_lru_del);
bool list_lru_del_obj(struct list_lru *lru, struct list_head *item) { + bool ret; int nid = page_to_nid(virt_to_page(item)); - struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? - mem_cgroup_from_slab_obj(item) : NULL;
- return list_lru_del(lru, item, nid, memcg); + if (list_lru_memcg_aware(lru)) { + rcu_read_lock(); + ret = list_lru_del(lru, item, nid, mem_cgroup_from_slab_obj(item)); + rcu_read_unlock(); + } else { + ret = list_lru_del(lru, item, nid, NULL); + } + + return ret; } EXPORT_SYMBOL_GPL(list_lru_del_obj);