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[2003:cb:c715:ee00:4e24:cf8e:3de0:8819]) by smtp.gmail.com with ESMTPSA id l1-20020a5d4bc1000000b00323287186b2sm1615554wrt.29.2023.10.06.05.56.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Oct 2023 05:57:00 -0700 (PDT) Message-ID: <387a6703-b8fb-d2ed-16b1-5264b2c901aa@redhat.com> Date: Fri, 6 Oct 2023 14:56:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v2 3/4] mm/gup: make failure to pin an error if FOLL_NOWAIT not specified To: Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Catalin Marinas , Will Deacon , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland Cc: Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Oleg Nesterov , Richard Cochran , Jason Gunthorpe , John Hubbard , Arnd Bergmann References: <2a42d96dd1e37163f90a0019a541163dafb7e4c3.1696288092.git.lstoakes@gmail.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <2a42d96dd1e37163f90a0019a541163dafb7e4c3.1696288092.git.lstoakes@gmail.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-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 68E0D140043 X-Stat-Signature: tiua45hw66ifpkbkq3p1hq5ht371ahjt X-Rspam-User: X-HE-Tag: 1696597024-52898 X-HE-Meta: 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 KZbE7t0E 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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: On 03.10.23 01:14, Lorenzo Stoakes wrote: > There really should be no circumstances under which a non-FOLL_NOWAIT GUP > operation fails to return any pages, so make this an error and warn on it. > > To catch the trivial case, simply exit early if nr_pages == 0. > > This brings __get_user_pages_locked() in line with the behaviour of its > nommu variant. > > Reviewed-by: Arnd Bergmann > Signed-off-by: Lorenzo Stoakes > --- Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb