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[2003:cb:c72b:b500:b53e:6e32:1408:27ac]) by smtp.gmail.com with ESMTPSA id r2-20020a056000014200b003366224319csm5554623wrx.53.2023.12.18.09.06.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Dec 2023 09:06:02 -0800 (PST) Message-ID: Date: Mon, 18 Dec 2023 18:06:00 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 13/39] mm/rmap: factor out adding folio mappings into __folio_add_rmap() Content-Language: en-US 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: <20231211155652.131054-1-david@redhat.com> <20231211155652.131054-14-david@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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 18.12.23 17:07, Ryan Roberts wrote: > On 11/12/2023 15:56, David Hildenbrand wrote: >> Let's factor it out to prepare for reuse as we convert >> page_add_anon_rmap() to folio_add_anon_rmap_[pte|ptes|pmd](). >> >> Make the compiler always special-case on the granularity by using >> __always_inline. >> >> Reviewed-by: Yin Fengwei >> Signed-off-by: David Hildenbrand >> --- >> mm/rmap.c | 81 ++++++++++++++++++++++++++++++------------------------- >> 1 file changed, 45 insertions(+), 36 deletions(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 2ff2f11275e5..c5761986a411 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1157,6 +1157,49 @@ int folio_total_mapcount(struct folio *folio) >> return mapcount; >> } >> >> +static __always_inline unsigned int __folio_add_rmap(struct folio *folio, >> + struct page *page, int nr_pages, enum rmap_mode mode, >> + unsigned int *nr_pmdmapped) >> +{ >> + atomic_t *mapped = &folio->_nr_pages_mapped; >> + int first, nr = 0; >> + >> + __folio_rmap_sanity_checks(folio, page, nr_pages, mode); >> + >> + /* Is page being mapped by PTE? Is this its first map to be added? */ > > I suspect this comment is left over from the old version? It sounds a bit odd in > its new context. In this patch, I'm just moving the code, so it would have to be dropped in a previous patch. I'm happy to drop all these comments in previous patches. > >> + switch (mode) { >> + case RMAP_MODE_PTE: >> + do { >> + first = atomic_inc_and_test(&page->_mapcount); >> + if (first && folio_test_large(folio)) { >> + first = atomic_inc_return_relaxed(mapped); >> + first = (first < COMPOUND_MAPPED); >> + } >> + >> + if (first) >> + nr++; >> + } while (page++, --nr_pages > 0); >> + break; >> + case RMAP_MODE_PMD: >> + first = atomic_inc_and_test(&folio->_entire_mapcount); >> + if (first) { >> + nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped); >> + if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) { >> + *nr_pmdmapped = folio_nr_pages(folio); >> + nr = *nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED); >> + /* Raced ahead of a remove and another add? */ >> + if (unlikely(nr < 0)) >> + nr = 0; >> + } else { >> + /* Raced ahead of a remove of COMPOUND_MAPPED */ >> + nr = 0; >> + } >> + } >> + break; >> + } >> + return nr; >> +} >> + >> /** >> * folio_move_anon_rmap - move a folio to our anon_vma >> * @folio: The folio to move to our anon_vma >> @@ -1380,45 +1423,11 @@ static __always_inline void __folio_add_file_rmap(struct folio *folio, >> struct page *page, int nr_pages, struct vm_area_struct *vma, >> enum rmap_mode mode) >> { >> - atomic_t *mapped = &folio->_nr_pages_mapped; >> - unsigned int nr_pmdmapped = 0, first; >> - int nr = 0; >> + unsigned int nr, nr_pmdmapped = 0; > > You're still being inconsistent with signed/unsigned here. Is there a reason > these can't be signed like nr_pages in the interface? I can turn them into signed values. Personally, I think it's misleading to use "signed" for values that have absolutely no meaning for negative meaning. But sure, we can be consistent, at least in rmap code. -- Cheers, David / dhildenb