diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 05c166811f6b..d4fc967247ae 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -91,15 +91,26 @@ void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *paren
  * @memcg: the cgroup of the sublist to add the item to.
  *
  * If the element is already part of a list, this function returns doing
- * nothing. Therefore the caller does not need to keep state about whether or
- * not the element already belongs in the list and is allowed to lazy update
- * it. Note however that this is valid for *a* list, not *this* list. If
- * the caller organize itself in a way that elements can be in more than
- * one type of list, it is up to the caller to fully remove the item from
- * the previous list (with list_lru_del() for instance) before moving it
- * to @lru.
+ * nothing. This means that it is not necessary to keep state about whether or
+ * not the element already belongs in the list. That said, this logic only
+ * works if the item is in *this* list. If the item might be in some other
+ * list, then you cannot rely on this check and you must remove it from the
+ * other list before trying to insert it.
  *
- * Return: true if the list was updated, false otherwise
+ * The lru list consists of many sublists internally; the @nid and @memcg
+ * parameters are used to determine which sublist to insert the item into.
+ * It's important to use the right value of @nid and @memcg when deleting the
+ * item, since it might otherwise get deleted from the wrong sublist.
+ *
+ * This also applies when attempting to insert the item multiple times - if
+ * the item is currently in one sublist and you call list_lru_add() again, you
+ * must pass the right @nid and @memcg parameters so that the same sublist is
+ * used.
+ *
+ * You must ensure that the memcg is not freed during this call (e.g., with
+ * rcu or by taking a css refcnt).
+ *
+ * Return value: true if the item was added, false otherwise
  */
 bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid,
 		    struct mem_cgroup *memcg);
@@ -113,7 +124,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid,
  * memcg of the sublist is determined by @item list_head. This assumption is
  * valid for slab objects LRU such as dentries, inodes, etc.
  *
- * Return value: true if the list was updated, false otherwise
+ * Return value: true if the item was added, false otherwise
  */
 bool list_lru_add_obj(struct list_lru *lru, struct list_head *item);
 
@@ -125,10 +136,21 @@ bool list_lru_add_obj(struct list_lru *lru, struct list_head *item);
  * @memcg: the cgroup of the sublist to delete the item from.
  *
  * This function works analogously as list_lru_add() in terms of list
- * manipulation. The comments about an element already pertaining to
- * a list are also valid for list_lru_del().
+ * manipulation.
+ *
+ * The comments in list_lru_add() about an element already being in a list are
+ * also valid for list_lru_del(), that is, you can delete an item that has
+ * already been removed or never been added. However, if the item is in a
+ * list, it must be in *this* list, and you must pass the right value of @nid
+ * and @memcg so that the right sublist is used.
+ *
+ * You must ensure that the memcg is not freed during this call (e.g., with
+ * rcu or by taking a css refcnt). When a memcg is deleted, list_lru entries
+ * are automatically moved to the parent memcg. This is done in a race-free
+ * way, so during deletion of an memcg both the old and new memcg will resolve
+ * to the same sublist internally.
  *
- * Return: true if the list was updated, false otherwise
+ * Return value: true if the item was removed, false otherwise
  */
 bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid,
 		    struct mem_cgroup *memcg);
@@ -142,7 +164,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid,
  * memcg of the sublist is determined by @item list_head. This assumption is
  * valid for slab objects LRU such as dentries, inodes, etc.
  *
- * Return value: true if the list was updated, false otherwise.
+ * Return value: true if the item was removed, false otherwise.
  */
 bool list_lru_del_obj(struct list_lru *lru, struct list_head *item);
 
