linux-kernel - Re: [PATCH RFC 34/39] mm/rmap: introduce folio_try_dup_anon_rmap

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Date:   Tue, 5 Dec 2023 14:18:39 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Ryan Roberts <ryan.roberts@....com>, linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Hugh Dickins <hughd@...gle.com>,
        Yin Fengwei <fengwei.yin@...el.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH RFC 34/39] mm/rmap: introduce
 folio_try_dup_anon_rmap_[pte|ptes|pmd]()

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@...hat.com>
>>> ---
>>>    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.

-- 
Cheers,

David / dhildenb