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[2003:cb:c72f:300:1ec7:2962:8889:ef6]) by smtp.gmail.com with ESMTPSA id ay10-20020a05600c1e0a00b0040b397787d3sm22603236wmb.24.2023.12.05.06.12.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Dec 2023 06:12:15 -0800 (PST) Message-ID: <9d3eb1e5-9fbb-487d-8fe9-066387671357@redhat.com> Date: Tue, 5 Dec 2023 15:12:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 34/39] mm/rmap: introduce folio_try_dup_anon_rmap_[pte|ptes|pmd]() To: Ryan Roberts , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , "Matthew Wilcox (Oracle)" , Hugh Dickins , Yin Fengwei , Mike Kravetz , Muchun Song , Peter Xu References: <20231204142146.91437-1-david@redhat.com> <20231204142146.91437-35-david@redhat.com> <88a341bf-0b6a-454a-aeb1-0699233eb37c@redhat.com> <181a1623-9285-415e-9ec6-6b6548ca7487@arm.com> <0f2bc27e-af1a-4590-985a-dc6bacdbcd57@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: B0E6220031 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: q5f6h93adsudqek3o4w55ekbddn1fuz5 X-HE-Tag: 1701785539-659054 X-HE-Meta: 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 VNbFvRw8 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05.12.23 15:02, Ryan Roberts wrote: > On 05/12/2023 13:50, David Hildenbrand wrote: >> On 05.12.23 14:40, Ryan Roberts wrote: >>> 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 >>>>>>> --- >>>>>>>     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? >> >> Good point, I didn't really consider that here, and thinking about it it makes >> perfect sense. >> >> I think the compiler might even ignore "always_inline". I read that especially >> with recursion the compiler might ignore that. But people can then complain to >> the compiler writers about performance issues here, we told the compiler what we >> think is best. >> > > To be honest, my comment assumed that you had a good reason for using > __always_inline, and in that case then you should be consistent. But if you > don't have a good reason, you should probably just use inline and let the > compiler do what it thinks best? I think __always_inline is the right thing to do here, we really want the compiler to generate specialized code. I was just somehow ignoring the scenario you described :) __always_inline it is. -- Cheers, David / dhildenb