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b=BlNTob1J/lh6sEaQcarMkth5pJXdUNvMvpAXR956QDl9Hddm0WQTfBbC7EQUos6Pw Ca2No0QrbKNf2IDtvcnHn4FIv8OqEb++geeQRTHTUZVkYhX+yllpAu2YFJjmMsdm7b g8NccKFLc+kKiWDh86dv33DsjU91FT1o3ftfLKDw= Date: Tue, 11 Jun 2024 11:21:31 -0700 From: Andrew Morton To: Matthew Wilcox Cc: Andrew Bresticker , David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/memory: Don't require head page for do_set_pmd() Message-Id: <20240611112131.25925b8ee5198668b88de35f@linux-foundation.org> In-Reply-To: References: <20240611153216.2794513-1-abrestic@rivosinc.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Stat-Signature: agi8n574jy51i6xmar5k65rutcq8icx5 X-Rspamd-Queue-Id: 4C19E80002 X-Rspam-User: X-HE-Tag: 1718130093-644688 X-HE-Meta: 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 IRg5YAyF 12xFIs/zaK1UAOcVttOtEM5CT3mHKV0bvn6/CrRYjpvgs2bQ5P6jmKlkDXffPzAu4ZhZ57rWos9jiN6k4feWdEey7AJwqVRI9j3ScwlPTCtbtDmptzG6cEbXH2ree4hBJ0TGS9yWI2+QKRhCQ2+bfoyQkKFEY2AbjgBqBjWOHjRb3mL4NqTtBvFvtiNvtCh7UpCF1Hs7sjC8kMTW7t1gKuIF7uXQf30eLQkO5QZGZQY64ZtdUhs35prUfS7blKUPXZ2xwbiN9jRVEtiH1E37FGDQt/nksu/mCKCwlk2Fq+PSYWGOo8hlGhs5UqsjfvE2kDJzrkXU07Us5eiU= 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 Tue, 11 Jun 2024 19:03:29 +0100 Matthew Wilcox wrote: > On Tue, Jun 11, 2024 at 08:32:16AM -0700, Andrew Bresticker wrote: > > - if (page != &folio->page || folio_order(folio) != HPAGE_PMD_ORDER) > > + if (folio_order(folio) != HPAGE_PMD_ORDER) > > return ret; > > + page = &folio->page; > > This works today, but in about six months time it's going to be a pain. > > + page = folio_page(folio, 0); > > is the one which works today and in the future. I was wondering about that. hp2:/usr/src/25> fgrep "&folio->page" mm/*.c | wc -l 84 hp2:/usr/src/25> fgrep "folio_page(" mm/*.c | wc -l 35 Should these all be converted? What's the general rule here?