Re: [syzbot] [mm?] [f2fs?] [exfat?] memory leak in __kfree_rcu_sheaf

[Qing Wang]

#syz test

diff --git a/mm/slub.c b/mm/slub.c
index cdc1e652ec52..387979b89120 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -6307,15 +6307,21 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj)
 			goto fail;
 
 		if (!local_trylock(&s->cpu_sheaves->lock)) {
-			barn_put_empty_sheaf(barn, empty);
+			if (barn && data_race(barn->nr_empty) < MAX_EMPTY_SHEAVES)
+				barn_put_empty_sheaf(barn, empty);
+			else
+				free_empty_sheaf(s, empty);
 			goto fail;
 		}
 
 		pcs = this_cpu_ptr(s->cpu_sheaves);
 
-		if (unlikely(pcs->rcu_free))
-			barn_put_empty_sheaf(barn, empty);
-		else
+		if (unlikely(pcs->rcu_free)) {
+			if (barn && data_race(barn->nr_empty) < MAX_EMPTY_SHEAVES)
+				barn_put_empty_sheaf(barn, empty);
+			else
+				free_empty_sheaf(s, empty);
+		} else
 			pcs->rcu_free = empty;
 	}