Re: WARNING: CPU: 0 PID: 11655 at mm/page_counter.c:62

[Roman Gushchin <guro@xxxxxx>]

On Tue, Jun 18, 2019 at 07:08:26PM -0700, Andrei Vagin wrote:
> Hello,
> 
> We run CRIU tests on linux-next kernels and today we found this
> warning in the kernel log:

Hello, Andrei!

Can you, please, check if the following patch fixes the problem?

Thanks a lot!

--

diff --git a/mm/slab.h b/mm/slab.h
index a4c9b9d042de..7667dddb6492 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -326,7 +326,8 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order,
        memcg = READ_ONCE(s->memcg_params.memcg);
        lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg);
        mod_lruvec_state(lruvec, cache_vmstat_idx(s), -(1 << order));
-       memcg_kmem_uncharge_memcg(page, order, memcg);
+       if (!mem_cgroup_is_root(memcg))
+               memcg_kmem_uncharge_memcg(page, order, memcg);
        rcu_read_unlock();
 
        percpu_ref_put_many(&s->memcg_params.refcnt, 1 << order);