on 8/6/2023 1:11 AM, Andrew Morton wrote:
> On Sat, 5 Aug 2023 19:07:03 +0800 Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> wrote:
>
>> The freepage is chained with buddy_list in freelist head. Use buddy_list
>> instead of lru to correct the list operation.
>>
>> ...
>>
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1395,8 +1395,8 @@ move_freelist_head(struct list_head *freelist, struct page *freepage)
>> {
>> LIST_HEAD(sublist);
>>
>> - if (!list_is_last(freelist, &freepage->lru)) {
>> - list_cut_before(&sublist, freelist, &freepage->lru);
>> + if (!list_is_last(freelist, &freepage->buddy_list)) {
>> + list_cut_before(&sublist, freelist, &freepage->buddy_list);
>> list_splice_tail(&sublist, freelist);
>> }
>> }
>> @@ -1412,8 +1412,8 @@ move_freelist_tail(struct list_head *freelist, struct page *freepage)
>> {
>> LIST_HEAD(sublist);
>>
>> - if (!list_is_first(freelist, &freepage->lru)) {
>> - list_cut_position(&sublist, freelist, &freepage->lru);
>> + if (!list_is_first(freelist, &freepage->buddy_list)) {
>> + list_cut_position(&sublist, freelist, &freepage->buddy_list);
>> list_splice_tail(&sublist, freelist);
>> }
>> }
>
> This looks like a significant error. Can we speculate about the
> possible runtime effects?
>
>
> It seems no runtime effects for now as lru and buddy_list share
the same memory address in a union.
