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b=DMeCpVFj6xuNgEpmQg1zia+EB1nBbXPjHKzpR/UVERO+nuN4wz1pK6tE6NrS4O8Ih JfifjGq3V22BCCMwlaKeT5qR8qcjcPTOBwAnG5gJd5pFFTo/PMNfDaAfHYakuPuik4 cvBCW8mWhdMYvczzkeV0FwJun2IT4KRtP/XVOmUiFPeyFOljLR9fgpZ3+VQHI2ERGd Cmpfax8Osj15CK1XcutgwE3EyDcv8gYKbDh3g9e9bHJke6UY8A2G9s3yC8oN9r1UW8 2X3HGF6OkTpp6cpnM7iCyHu/jn8z1cy/cgOVy8KeZkW+VRrAe9kQyUT/f0K6fszUXE nEYJfpVzXjxww== Message-ID: Date: Wed, 30 Sep 2026 12:17:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/15] mm: eliminate &folio->page references in mm/ To: Nilay Vaish , Andrew Morton Cc: Matthew Wilcox , Greg Thelen , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260929215206.516490-1-nilayvaish@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260929215206.516490-1-nilayvaish@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: zyjt88f433dmmaj1oz68icgd76eh6mk1 X-Rspamd-Queue-Id: 946FE180008 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1790763468-544763 X-HE-Meta: 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 ln5gw5kU 4m4aKDtNCcBPZwr3DNGmA0nPLWXcsG2nP8noE+L/PkLJ88Rqhuhv7TxoQbpjgmAbUiAAydNEoSYo4tGxqaTO8UuZt+f0NGJxG15BxnjzpsXz9wxPbQTbUBNSzsHdU1q9MLqqNbh2N5o8viJfp3z81kYzbRSyPnN0WMwhKigTHYalzHEgBALyORjrhC9TpGrXDhKRM45OOo6wAKXMy12n8iSnUOfgU6k4E8m7srIsVAmQxCAfzqy+x+34QzaNAmpZ7bK4e Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/29/26 23:51, Nilay Vaish wrote: > As part of the memdescs effort to separate struct folio from struct page > and allocate struct folio dynamically [1], struct folio will no longer > embed a struct page member (folio->page), and the address of a struct > folio will no longer equal the address of its head struct page in > vmemmap. > > This series eliminates all but one of the remaining &folio->page > references across mm/*.c (25 files) by converting them to: I recall that Willy mentioned at some point that when changing this we actually have to think about what the right thing to do is. As &folio->page can serve as a reminder that something needs a proper solution instead of a mechanical change. So while folio_page(folio, 0) is the mechanical change, a much more often we'll have to ask us what the actual future-proof thing is. For example: diff --git a/mm/migrate.c b/mm/migrate.c index 7bdcdb57652f..b027c938d830 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -266,8 +266,8 @@ void putback_movable_pages(struct list_head *l) continue; } list_del(&folio->lru); - if (unlikely(page_has_movable_ops(&folio->page))) { - putback_movable_ops_page(&folio->page); + if (unlikely(page_has_movable_ops(folio_page(folio, 0)))) { + putback_movable_ops_page(folio_page(folio, 0)); } else { node_stat_mod_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio), -folio_nr_pages(folio)); Is stupid. These things won't be folios in the future, so we actually *want to keep* using &folio->page here as a reminder that this really must be reworked entirely differently. Which makes this rather hard to review and makes me wonder whether core maintainers should actually drive such a cleanup. Unless Willy explicitly asked you to do that work, of course. -- Cheers, David