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[2003:cb:c73e:8900:2d8:c9f0:f3fb:d4fd]) by smtp.gmail.com with ESMTPSA id w21-20020a05600c475500b003feae747ff2sm16781241wmo.35.2023.11.14.01.23.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Nov 2023 01:23:58 -0800 (PST) Message-ID: Date: Tue, 14 Nov 2023 10:23:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/gup: Introduce pin_user_pages_fd() for pinning shmem/hugetlbfs file pages (v3) To: Vivek Kasireddy , dri-devel@lists.freedesktop.org, linux-mm@kvack.org Cc: Daniel Vetter , Mike Kravetz , Hugh Dickins , Peter Xu , Gerd Hoffmann , Dongwon Kim , Junxiao Chang , Jason Gunthorpe References: <0f05cade-c75e-4605-8e22-9fb916c622b0@redhat.com> <20231114070044.464451-1-vivek.kasireddy@intel.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: <20231114070044.464451-1-vivek.kasireddy@intel.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-Stat-Signature: zsu7caemwjo99j8dwwj7rtx9huu8qjmo X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: F3EBC180003 X-Rspam-User: X-HE-Tag: 1699953842-853064 X-HE-Meta: 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 q6iLglar 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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 14.11.23 08:00, Vivek Kasireddy wrote: > For drivers that would like to longterm-pin the pages associated > with a file, the pin_user_pages_fd() API provides an option to > not only pin the pages via FOLL_PIN but also to check and migrate > them if they reside in movable zone or CMA block. This API > currently works with files that belong to either shmem or hugetlbfs. > Files belonging to other filesystems are rejected for now. > > The pages need to be located first before pinning them via FOLL_PIN. > If they are found in the page cache, they can be immediately pinned. > Otherwise, they need to be allocated using the filesystem specific > APIs and then pinned. > > v2: > - Drop gup_flags and improve comments and commit message (David) > - Allocate a page if we cannot find in page cache for the hugetlbfs > case as well (David) > - Don't unpin pages if there is a migration related failure (David) > - Drop the unnecessary nr_pages <= 0 check (Jason) > - Have the caller of the API pass in file * instead of fd (Jason) > > v3: (David) > - Enclose the huge page allocation code with #ifdef CONFIG_HUGETLB_PAGE > (Build error reported by kernel test robot ) > - Don't forget memalloc_pin_restore() on non-migration related errors > - Improve the readability of the cleanup code associated with > non-migration related errors > - Augment the comments by describing FOLL_LONGTERM like behavior > - Include the R-b tag from Jason > > Cc: David Hildenbrand > Cc: Daniel Vetter > Cc: Mike Kravetz > Cc: Hugh Dickins > Cc: Peter Xu > Cc: Gerd Hoffmann > Cc: Dongwon Kim > Cc: Junxiao Chang > Suggested-by: Jason Gunthorpe > Reviewed-by: Jason Gunthorpe (v2) > Signed-off-by: Vivek Kasireddy > --- > include/linux/mm.h | 2 + > mm/gup.c | 109 +++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 111 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 418d26608ece..1b675fa35059 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2472,6 +2472,8 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, > struct page **pages, unsigned int gup_flags); > long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, > struct page **pages, unsigned int gup_flags); > +long pin_user_pages_fd(struct file *file, pgoff_t start, > + unsigned long nr_pages, struct page **pages); > > 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 231711efa390..b3af967cdff1 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -3410,3 +3410,112 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, > &locked, gup_flags); > } > EXPORT_SYMBOL(pin_user_pages_unlocked); > + > +static struct page *alloc_file_page(struct file *file, pgoff_t idx) > +{ > +#ifdef CONFIG_HUGETLB_PAGE > + struct page *page = ERR_PTR(-ENOMEM); > + struct folio *folio; > + int err; > + > + if (is_file_hugepages(file)) { > + folio = alloc_hugetlb_folio_nodemask(hstate_file(file), > + NUMA_NO_NODE, > + NULL, > + GFP_USER); > + if (folio && folio_try_get(folio)) { > + page = &folio->page; > + err = hugetlb_add_to_page_cache(folio, > + file->f_mapping, > + idx); > + if (err) { > + folio_put(folio); > + free_huge_folio(folio); > + page = ERR_PTR(err); > + } > + } > + return page; You could avoid the "page" variable completely simply by using 3 return statements. LGTM, thanks Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb