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

Qing Wang
2026-03-02T03:41:12Z

#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;
}