Re: [PATCH] mm/memcg: remove definition of MEM_CGROUP_ID_MAX when !CONFIG_MEMCG

[Muchun Song]

> On Jul 6, 2023, at 19:28, Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
> 
> MEM_CGROUP_ID_MAX is only used when CONFIG_MEMCG is configured. Remove
> unneeded !CONFIG_MEMCG variant.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>

MEM_CGROUP_ID_MAX is also only used in mem_cgroup_alloc(), maybe you also
could move it from memcontrol.h to memcontrol.c. And define it as:

#define MEM_CGROUP_ID_MAX ((1U << MEM_CGROUP_ID_SHIFT) - 1)

I am not suggesting defining it as USHRT_MAX, because if someone changes
MEM_CGROUP_ID_SHIFT in the future, then MEM_CGROUP_ID_MAX will not updated
accordingly.

For this patch, LGTM.

Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>

Thanks.