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[78.132.105.44]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-378e72e4cf7sm9393827f8f.11.2024.09.17.05.25.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Sep 2024 05:25:49 -0700 (PDT) Message-ID: <6aea6530-9f9c-4a9c-9c9c-2c29e8ae9e9d@redhat.com> Date: Tue, 17 Sep 2024 14:25:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V1 1/9] mm/gup: repin_folio_unhugely To: Steven Sistare , linux-mm@kvack.org Cc: Jason Gunthorpe , Kevin Tian , Nicolin Chen , iommu@lists.linux.dev, Andrew Morton , Matthew Wilcox References: <1726319158-283074-1-git-send-email-steven.sistare@oracle.com> <1726319158-283074-2-git-send-email-steven.sistare@oracle.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: 7bit X-Stat-Signature: qsrpgd7omqacb75brkxtw9znzusxc8au X-Rspamd-Queue-Id: 3971E4001A X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1726575955-903166 X-HE-Meta: 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 /KAkIyp8 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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 14.09.24 15:19, Steven Sistare wrote: > cc'ing linux-mm for review of this one patch of the series. > > This proposes a new KAPI function repin_folio_unhugely(), for use in this > patch of the iommu_ioas_map_file series: > > iommufd: IOMMU_IOAS_MAP_FILE implementation > https://lore.kernel.org/linux-iommu/1726319158-283074-7-git-send-email-steven.sistare@oracle.com > > - Steve > > On 9/14/2024 9:05 AM, Steve Sistare wrote: >> Export a function that repins a huge-page folio at small-page granularity. >> This allows any range of small pages within the folio to be unpinned later. >> For example, pages pinned via memfd_pin_folios and modified by >> repin_folio_unhugely could be unpinned via unpin_user_page(s). >> >> Suggested-by: Jason Gunthorpe >> Signed-off-by: Steve Sistare >> --- >> include/linux/mm.h | 1 + >> mm/gup.c | 18 ++++++++++++++++++ >> 2 files changed, 19 insertions(+) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 1470736..ba8344f 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -2514,6 +2514,7 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, >> long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, >> struct folio **folios, unsigned int max_folios, >> pgoff_t *offset); >> +void repin_folio_unhugely(struct folio *folio, unsigned long npin); >> >> int get_user_pages_fast(unsigned long start, int nr_pages, >> unsigned int gup_flags, struct page **pages); >> diff --git a/mm/gup.c b/mm/gup.c >> index 947881ff..f8f3f2a 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -3720,3 +3720,21 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, >> return ret; >> } >> EXPORT_SYMBOL_GPL(memfd_pin_folios); >> + >> +/** >> + * repin_folio_unhugely() - repin a folio at small page granularity >> + * @folio: the folio to repin >> + * @npin: the number of pages pinned in the folio >> + * >> + * Given a huge page folio that is already pinned, and the number of small s/huge page folio/large folio/ >> + * pages that are pinned in it, adjust the pincount to reflect small-page >> + * granularity. Each small page can later be unpinned individually. >> + */ >> +void repin_folio_unhugely(struct folio *folio, unsigned long npin) >> +{ >> + if (!folio_test_large(folio) || is_huge_zero_folio(folio) || npin == 1) Why not the huge zero folio? That looks very odd here. >> + return; >> + atomic_add(npin - 1, &folio->_refcount); >> + atomic_add(npin - 1, &folio->_pincount); >> +} >> +EXPORT_SYMBOL_GPL(repin_folio_unhugely); Can we ... find a better name? For example, it's "large" folio not "huge"... And repin is really misleading. We are simply adding more pins to an already pinned one ... -- Cheers, David / dhildenb