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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id s27-20020a05620a031b00b007592f2016f4sm3679473qkm.110.2023.06.13.08.45.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jun 2023 08:45:18 -0700 (PDT) Date: Tue, 13 Jun 2023 11:45:16 -0400 From: Peter Xu To: David Hildenbrand Cc: Jason Gunthorpe , Matthew Wilcox , David Rientjes , Mike Kravetz , Yosry Ahmed , James Houghton , Naoya Horiguchi , Miaohe Lin , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, Michal Hocko , Axel Rasmussen , Jiaqi Yan Subject: Re: [LSF/MM/BPF TOPIC] HGM for hugetlbfs Message-ID: References: <7e0ce268-f374-8e83-2b32-7c53f025fec5@google.com> <7c42a738-d082-3338-dfb5-fd28f75edc58@redhat.com> <75d5662a-a901-1e02-4706-66545ad53c5c@redhat.com> <20230607220651.GC4122@monkey> <686e3e61-704e-1258-8a8b-f18399b41668@google.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: BEA42120021 X-Rspam-User: X-Stat-Signature: 398i4owu9eotgybca6fdyzxsr7buxujs X-Rspamd-Server: rspam01 X-HE-Tag: 1686671123-263063 X-HE-Meta: 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 IQX4uu7N Q2uiUaZhTbDpNx4a/8Y3Qf5VXsTvK/dZIdiOqu3wJgtevQoHyZAX8J8qipx5biLpJdvj0rLrmSKoWtKr8pMpIu5eZPEbwUShIVMUklHpSLFNKp4LGuhf5sMC/hgOALFLAGc4/eBOMRxDx9u3wRTHuJQM3FFW82QwugIDdcahr0PyKkaum2ZaepWYmURG7iU3XR/diH03AmDjcFK2ULvvYCzLUQEgfek/nQPoeSS0Qgpw6p35u7pe/Hh7KDgVVmcn8lXyx8RtL9yCrM836JcXizs4aZJ0IVYLWA6LKF+LDJW9H3CHtSfYvNS6MKCMSWYBTh/q8aNcdvJF39cOM0KmtEbtzc0tu0Q2oEXYUCA23KWBCJYymplFOfZ3I4Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.008602, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jun 13, 2023 at 05:15:36PM +0200, David Hildenbrand wrote: > Doing all the conversion in-place could turn out extremely painful and take > much longer ... but I might be just taught otherwise. IMHO we should start with the attempt of in-place conversion always, and we should provide good reasonings to justify every single point of a change to v1: either a design flaw that we must change, or when impossible to convert without breaking v1. The "pain" is already there. IMHO any new v2 proposal should be able to list out all the "pain"s (it'll be a vain if we "silently" carry over a pain point, so a detailed summary of the problem along with reasonings to change, what is the right things to do, can be half way already of the whole effort..), and (2) justify the "pain"s are gone in the new design. -- Peter Xu