Re: [PATCH RFC 34/39] mm/rmap: introduce folio_try_dup_anon_rmap_[pte|ptes|pmd]()

[Ryan Roberts]

On 05/12/2023 13:18, David Hildenbrand wrote:
> On 05.12.23 14:17, David Hildenbrand wrote:
>> On 05.12.23 14:12, Ryan Roberts wrote:
>>> On 04/12/2023 14:21, David Hildenbrand wrote:
>>>> The last user of page_needs_cow_for_dma() and __page_dup_rmap() are gone,
>>>> remove them.
>>>>
>>>> Add folio_try_dup_anon_rmap_ptes() right away, we want to perform rmap
>>>> baching during fork() soon.
>>>>
>>>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>>>> ---
>>>>    include/linux/mm.h   |   6 --
>>>>    include/linux/rmap.h | 145 +++++++++++++++++++++++++++++--------------
>>>>    2 files changed, 100 insertions(+), 51 deletions(-)
>>>>
>>>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>>>> index 24c1c7c5a99c0..f7565b35ae931 100644
>>>> --- a/include/linux/mm.h
>>>> +++ b/include/linux/mm.h
>>>> @@ -1964,12 +1964,6 @@ static inline bool folio_needs_cow_for_dma(struct
>>>> vm_area_struct *vma,
>>>>        return folio_maybe_dma_pinned(folio);
>>>>    }
>>>>    -static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
>>>> -                      struct page *page)
>>>> -{
>>>> -    return folio_needs_cow_for_dma(vma, page_folio(page));
>>>> -}
>>>> -
>>>>    /**
>>>>     * is_zero_page - Query if a page is a zero page
>>>>     * @page: The page to query
>>>> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
>>>> index 21d72cc602adc..84439f7720c62 100644
>>>> --- a/include/linux/rmap.h
>>>> +++ b/include/linux/rmap.h
>>>> @@ -354,68 +354,123 @@ static inline void folio_dup_file_rmap_pmd(struct
>>>> folio *folio,
>>>>    #endif
>>>>    }
>>>>    -static inline void __page_dup_rmap(struct page *page, bool compound)
>>>> +static inline int __folio_try_dup_anon_rmap(struct folio *folio,
>>>
>>> __always_inline?
>>
>> Yes.
> 
> Ah, no, I did this for a reason. This function lives in a header, so it will
> always be inlined.
> 

Really? It will certainly be duplicated across every compilation unit, but
that's separate from being inlined - if the optimizer is off, won't it just end
up as an out-of-line function in every compilation unit?