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[2003:cb:c732:e600:4982:2903:710f:f20a]) by smtp.gmail.com with ESMTPSA id k35-20020a05600c1ca300b004156afd6843sm4887490wms.18.2024.04.02.07.14.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Apr 2024 07:14:10 -0700 (PDT) Message-ID: <17756b00-b051-40de-afa2-c3df97de755f@redhat.com> Date: Tue, 2 Apr 2024 16:14:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 1/8] mm/gup: Introduce unpin_folio/unpin_folios helpers From: David Hildenbrand To: Vivek Kasireddy , dri-devel@lists.freedesktop.org, linux-mm@kvack.org Cc: Matthew Wilcox , Christoph Hellwig , Jason Gunthorpe , Peter Xu References: <20240225080008.1019653-1-vivek.kasireddy@intel.com> <20240225080008.1019653-2-vivek.kasireddy@intel.com> <54381897-35bc-442d-951d-b9a89f16b1a5@redhat.com> 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: <54381897-35bc-442d-951d-b9a89f16b1a5@redhat.com> 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-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 02.04.24 15:52, David Hildenbrand wrote: > On 25.02.24 08:56, Vivek Kasireddy wrote: >> These helpers are the folio versions of unpin_user_page/unpin_user_pages. >> They are currently only useful for unpinning folios pinned by >> memfd_pin_folios() or other associated routines. However, they could >> find new uses in the future, when more and more folio-only helpers >> are added to GUP. >> >> Cc: David Hildenbrand >> Cc: Matthew Wilcox >> Cc: Christoph Hellwig >> Cc: Jason Gunthorpe >> Cc: Peter Xu >> Suggested-by: David Hildenbrand >> Signed-off-by: Vivek Kasireddy >> --- >> include/linux/mm.h | 2 ++ >> mm/gup.c | 81 ++++++++++++++++++++++++++++++++++++++++------ >> 2 files changed, 74 insertions(+), 9 deletions(-) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 6f4825d82965..36e4c2b22600 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -1601,11 +1601,13 @@ static inline void put_page(struct page *page) >> #define GUP_PIN_COUNTING_BIAS (1U << 10) >> >> void unpin_user_page(struct page *page); >> +void unpin_folio(struct folio *folio); >> void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages, >> bool make_dirty); >> void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages, >> bool make_dirty); >> void unpin_user_pages(struct page **pages, unsigned long npages); >> +void unpin_folios(struct folio **folios, unsigned long nfolios); >> >> static inline bool is_cow_mapping(vm_flags_t flags) >> { >> diff --git a/mm/gup.c b/mm/gup.c >> index df83182ec72d..0a45eda6aaeb 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -30,6 +30,23 @@ struct follow_page_context { >> unsigned int page_mask; >> }; >> >> +static inline void sanity_check_pinned_folios(struct folio **folios, >> + unsigned long nfolios) >> +{ >> + if (!IS_ENABLED(CONFIG_DEBUG_VM)) >> + return; >> + >> + for (; nfolios; nfolios--, folios++) { >> + struct folio *folio = *folios; >> + >> + if (is_zero_folio(folio) || >> + !folio_test_anon(folio)) >> + continue; >> + >> + VM_BUG_ON_FOLIO(!PageAnonExclusive(&folio->page), folio); > > That change is wrong (and the split makes the check confusing). > > It could be that the first subpage is no longer exclusive, but the given > (sanity_check_pinned_pages() ) subpage is exclusive for large folios. > > I suggest dropping that change, and instead, in > unpin_folio()/unpin_folios(), reject any anon folios for now. > > So, replace the sanity_check_pinned_folios() in unpin_folio() / > unpin_folios() by a VM_WARN_ON(folio_test_anon(folio)); After reading patch #2: drop both the sanity check and VM_WARN_ON() from unpin_folio()/unpin_folios(), and add a comment to the patch description that we cannot do the sanity checking without the subpage, and that we can reintroduce it once we have a single per-folio AnonExclusive bit. -- Cheers, David / dhildenb