Re: [PATCH] mm: remove offset check on page->compound_head and folio->lru

Wei Yang
2022-02-24T01:37:37Z

On Mon, Jan 24, 2022 at 11:30:10AM +0100, Vlastimil Babka wrote:
[...]
>> Hi, Matthew
>>
>> Are you back from vocation? If you could give more insight on this check, I
>> would be appreciated.
>
>I can offer my insight (which might be of course wrong). Ideally one day
>page.lru will be gone and only folio will be used for LRU pages. Then there
>won't be a FOLIO_MATCH(lru, lru); and FOLIO_MATCH(compound_head, lru);
>won't appear to be redundant anymore. lru is list_head so two pointers and
>thus valid pointers are aligned in such a way they can't accidentaly set the
>bit 0.
>

Hmm... I see your change on struct slab. I guess I got your point.

Seems we would shrink struct page...