Re: [PATCHv4 1/8] mm: Add support for unaccepted memory

David Hildenbrand
2022-04-11T08:47:39Z

>>> if (fpi_flags & FPI_TO_TAIL)
>>> to_tail = true;
>>> else if (is_shuffle_order(order))
>>> @@ -1149,7 +1192,8 @@ static inline void __free_one_page(struct page *page,
>>> static inline bool page_expected_state(struct page *page,
>>> unsigned long check_flags)
>>> {
>>> - if (unlikely(atomic_read(&page->_mapcount) != -1))
>>> + if (unlikely(atomic_read(&page->_mapcount) != -1) &&
>>> + !PageUnaccepted(page))
>>> return false;
>>
>> That probably deserves a comment, and maybe its own if() statement.
>
> Own if does not work. PageUnaccepted() is encoded in _mapcount.
>
> What about this:
>
> /*
> * page->_mapcount is expected to be -1.
> *
> * There is an exception for PageUnaccepted(). The page type can be set
> * for pages on free list. Page types are encoded in _mapcount.
> *
> * PageUnaccepted() will get cleared in post_alloc_hook().
> */
> if (unlikely((atomic_read(&page->_mapcount) | PG_unaccepted) != -1))
> return false;
>
> ?
>

Please don't. Keep the usage of PG_* details inside page-flags.h

--
Thanks,

David / dhildenb