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[2003:cb:c718:9a00:a5f5:5315:b9fa:64df]) by smtp.gmail.com with ESMTPSA id p9-20020adfce09000000b0031763fd36c4sm21300996wrn.104.2023.08.03.02.35.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Aug 2023 02:35:00 -0700 (PDT) Message-ID: <007ae337-1e92-d43f-6204-5987698aa7bf@redhat.com> Date: Thu, 3 Aug 2023 11:34:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 0/4] mm: migrate: more folio conversion To: Kefeng Wang , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Huang Ying , Matthew Wilcox References: <20230802095346.87449-1-wangkefeng.wang@huawei.com> <32b748d2-3d88-87d6-3797-c82d7bb7a927@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <32b748d2-3d88-87d6-3797-c82d7bb7a927@huawei.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-Queue-Id: 5C9314002E X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: nnkw85tjabgrb63bz43r4m77boxx8xoz X-HE-Tag: 1691055305-647402 X-HE-Meta: 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 c+If2QXr DVId+rFMvxdk7ENkAqVSAkJ3HfMXVdOP4j5IGEIucAnuTvu9udAITgsYcbmrZ5heC/0P5Q0bZr8lskDsqTScnVVyT1JxjRuv7cSVlxeKrGhG2bkPrFPvuiJetqeYn+h1sJzD/ciAGJCIacafRqrbzxP1LlQSPDIc0L8XFBi1kVaBgWSeLGkpAvP/oCINBmOosmEeNKJF3rrk/4wgOxaKzdP0EiSULoEYGAOO2sgd+z1WvJAu0oov8NhXCl73Mzswvtn9SEcYEk1B3/GJRCHb1BqHMdGVRmYkckYao/+SGyGtdra45bpRZwd8opPErF4rNyrvtXs4spmo9DKnNOE38qITb3krv41LRtVOp4hvXwV2N1ZNkM6VUNfhMOv79QxH/ZXMe 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 02.08.23 14:38, Kefeng Wang wrote: > > > On 2023/8/2 19:47, David Hildenbrand wrote: >> On 02.08.23 11:53, Kefeng Wang wrote: >>> This patch series converts several functions to use folio in migrate.c. >> >> Please clearly spell out in the patch descriptions when you are changing >> mapcount logic and which effects that might have (both, positive and >> negative) for PTE-mapped THP. > > Oh, I see your comments on another mail[1], the folio_estimated_sharers() > is not good to evaluate the sharing by multiple processes, will read more > history of the mail's discussion, maybe just ignore the first three patches. It might be good enough for some cases right now. My point is that we better just clearly spell out the possible effects of such a change. (so far you didn't even mention them, and that's sub-optimal when buried in a "folio" conversion that better shouldn't change the functionality without spelling it out) -- Cheers, David / dhildenb