mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_…

…node()" Commit 405cc51 ("mm/list_lru: optimize memcg_reparent_list_lru_node()") has subtle races which are proving ugly to fix. Revert the original optimization. If quantitative testing indicates that we have a significant problem here then other implementations can be looked at. Fixes: 405cc51 ("mm/list_lru: optimize memcg_reparent_list_lru_node()") Acked-by: Shakeel Butt <[email protected]> Reviewed-by: Muchun Song <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: Waiman Long <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Johannes Weiner <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mpe · Apr 9, 2022 · b33e104 · b33e104
1 parent 0347b2b
commit b33e104
Showing 1 changed file with 0 additions and 6 deletions.
diff --git a/mm/list_lru.c b/mm/list_lru.c
@@ -394,12 +394,6 @@ static void memcg_reparent_list_lru_node(struct list_lru *lru, int nid,
 	int dst_idx = dst_memcg->kmemcg_id;
 	struct list_lru_one *src, *dst;
 
-	/*
-	 * If there is no lru entry in this nlru, we can skip it immediately.
-	 */
-	if (!READ_ONCE(nlru->nr_items))
-		return;
-
 	/*
 	 * Since list_lru_{add,del} may be called under an IRQ-safe lock,
 	 * we have to use IRQ-safe primitives here to avoid deadlock.