On Mon, Mar 29, 2021 at 9:13 AM Muchun Song [off-list ref] wrote:

On Mon, Mar 29, 2021 at 10:49 PM Dan Schatzberg
[off-list ref] wrote:

[...]

Since remote memcg must hold a reference, we do not
need to do something like get_active_memcg() does.
Just use css_get to obtain a ref, it is simpler. Just
Like below.

+       if (unlikely(!mm)) {
+               memcg = active_memcg();
+               if (unlikely(memcg)) {
+                       /* remote memcg must hold a ref. */
+                       css_get(memcg);
+                       return memcg;
+               }

I second Muchun's suggestion.