On Thu, Aug 11, 2022 at 1:07 AM Shakeel Butt <shakeelb@xxxxxxxxxx> wrote:
>
> On Wed, Aug 10, 2022 at 03:18:30PM +0000, Yafang Shao wrote:
> > The memcg may be the root_mem_cgroup, in which case we shouldn't put it.
>
> No, it is ok to put root_mem_cgroup. css_put already handles the root
> cgroups.
>
Ah, this commit log doesn't describe the issue clearly. I should improve it.
The issue is that in bpf_map_get_memcg() it doesn't get the objcg if
map->objcg is NULL (that can happen if the map belongs to the root
memcg), so we shouldn't put the objcg if map->objcg is NULL neither in
bpf_map_put_memcg().
Maybe the change below would be more reasonable ?
+static void bpf_map_put_memcg(const struct bpf_map *map, struct
mem_cgroup *memcg)
+{
+ if (map->objcg)
+ mem_cgroup_put(memcg);
+}
--
Regards
Yafang
