On 24.11.19 01:39, Roman Gushchin wrote:
> On Fri, Nov 22, 2019 at 05:28:46PM +0100, Christian Borntraeger wrote:
>> On 21.11.19 19:45, Roman Gushchin wrote:
>>> I see. Do you know, which kmem_cache it is? If not, can you, please,
>>> figure it out?
>>
>> The release function for that ref is kmemcg_cache_shutdown.
>>
>
> Hi Christian!
>
> Can you, please, test if the following patch resolves the problem?
Yes, it does.
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 8afa188f6e20..628e5f0ee19e 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -888,6 +888,8 @@ static int shutdown_memcg_caches(struct kmem_cache *s)
>
> static void flush_memcg_workqueue(struct kmem_cache *s)
> {
> + bool wait_for_children;
> +
> spin_lock_irq(&memcg_kmem_wq_lock);
> s->memcg_params.dying = true;
> spin_unlock_irq(&memcg_kmem_wq_lock);
> @@ -904,6 +906,13 @@ static void flush_memcg_workqueue(struct kmem_cache *s)
> * previous workitems on workqueue are processed.
> */
> flush_workqueue(memcg_kmem_cache_wq);
> +
> + mutex_lock(&slab_mutex);
> + wait_for_children = !list_empty(&s->memcg_params.children);
> + mutex_unlock(&slab_mutex);
Not sure if (for reading) we really need the mutex.
> +
> + if (wait_for_children)
> + rcu_barrier();
> }
> #else
> static inline int shutdown_memcg_caches(struct kmem_cache *s)
>
> --
>
> Thanks!
>
