On Wed, Oct 02, 2024 at 02:25:34PM +0300, Dan Carpenter wrote:
> On Wed, Oct 02, 2024 at 02:24:20PM +0300, Dan Carpenter wrote:
> > Let's add Kairui Song to the CC list.
> >
> > One simple thing is that we should add a READ_ONCE() to the comparison. Naresh,
> > could you test the attached diff? I don't know that it will fix it but it's
> > worth checking the easy stuff first.
> >
>
> Actually that's not right. Let me write a different patch.
Try this one.
regards,
dan carpenter
diff --git a/mm/list_lru.c b/mm/list_lru.c
index 79c2d21504a2..2c429578ed31 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -65,6 +65,7 @@ lock_list_lru_of_memcg(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
bool irq, bool skip_empty)
{
struct list_lru_one *l;
+ long nr_items;
rcu_read_lock();
again:
l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
@@ -73,8 +74,9 @@ lock_list_lru_of_memcg(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
spin_lock_irq(&l->lock);
else
spin_lock(&l->lock);
- if (likely(READ_ONCE(l->nr_items) != LONG_MIN)) {
- WARN_ON(l->nr_items < 0);
+ nr_items = READ_ONCE(l->nr_items);
+ if (likely(nr_items != LONG_MIN)) {
+ WARN_ON(nr_items < 0);
rcu_read_unlock();
return l;
}
