On 2021/6/8 7:10, Andrew Morton wrote:
> On Sat, 5 Jun 2021 15:51:40 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
>
>> Since commit 9d8c5b5284e4 ("mm: zbud: fix condition check on allocation
>> size"), zbud_pool.unbuddied[0] is always unused. We can reuse it as buddied
>> field to save some possible memory.
>>
>> ...
>>
>> --- a/mm/zbud.c
>> +++ b/mm/zbud.c
>> @@ -96,7 +96,7 @@
>> struct zbud_pool {
>> spinlock_t lock;
>> struct list_head unbuddied[NCHUNKS];
>> - struct list_head buddied;
>> +#define buddied unbuddied[0]
>> struct list_head lru;
>> u64 pages_nr;
>> const struct zbud_ops *ops;
>
> That looks a bit hacky. Can we at least have a comment explaining
> what's going on?
>
> Would it be better to implement this with a union, rather than a #define?
It seems union is better and comment is necessary. Will try to do this.
Many thanks for your comment and reply!
> .
>
