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Received: from [96.67.55.146] by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1wps3w-000000002Tu-3LfS; Fri, 31 Jul 2026 14:34:28 -0400 Message-ID: Subject: Re: [PATCH RFC] mm/gup: batch contiguous pages in follow_page_mask() and return them via a pages array From: Rik van Riel To: "Lorenzo Stoakes (ARM)" Cc: David Hildenbrand , Andrew Morton , Jason Gunthorpe , Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Aristeu Rozanski Date: Fri, 31 Jul 2026 14:32:58 -0400 In-Reply-To: References: <20260730035350.1fc95dd8@fangorn> Autocrypt: addr=riel@surriel.com; prefer-encrypt=mutual; keydata=mQENBFIt3aUBCADCK0LicyCYyMa0E1lodCDUBf6G+6C5UXKG1jEYwQu49cc/gUBTTk33A eo2hjn4JinVaPF3zfZprnKMEGGv4dHvEOCPWiNhlz5RtqH3SKJllq2dpeMS9RqbMvDA36rlJIIo47 Z/nl6IA8MDhSqyqdnTY8z7LnQHqq16jAqwo7Ll9qALXz4yG1ZdSCmo80VPetBZZPw7WMjo+1hByv/ lvdFnLfiQ52tayuuC1r9x2qZ/SYWd2M4p/f5CLmvG9UcnkbYFsKWz8bwOBWKg1PQcaYHLx06sHGdY dIDaeVvkIfMFwAprSo5EFU+aes2VB2ZjugOTbkkW2aPSWTRsBhPHhV6dABEBAAG0HlJpayB2YW4gU mllbCA8cmllbEByZWRoYXQuY29tPokBHwQwAQIACQUCW5LcVgIdIAAKCRDOed6ShMTeg05SB/986o gEgdq4byrtaBQKFg5LWfd8e+h+QzLOg/T8mSS3dJzFXe5JBOfvYg7Bj47xXi9I5sM+I9Lu9+1XVb/ r2rGJrU1DwA09TnmyFtK76bgMF0sBEh1ECILYNQTEIemzNFwOWLZZlEhZFRJsZyX+mtEp/WQIygHV WjwuP69VJw+fPQvLOGn4j8W9QXuvhha7u1QJ7mYx4dLGHrZlHdwDsqpvWsW+3rsIqs1BBe5/Itz9o 6y9gLNtQzwmSDioV8KhF85VmYInslhv5tUtMEppfdTLyX4SUKh8ftNIVmH9mXyRCZclSoa6IMd635 Jq1Pj2/Lp64tOzSvN5Y9zaiCc5FucXtB9SaWsgdmFuIFJpZWwgPHJpZWxAc3VycmllbC5jb20+iQE +BBMBAgAoBQJSLd2lAhsjBQkSzAMABgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRDOed6ShMTe g4PpB/0ZivKYFt0LaB22ssWUrBoeNWCP1NY/lkq2QbPhR3agLB7ZXI97PF2z/5QD9Fuy/FD/jddPx KRTvFCtHcEzTOcFjBmf52uqgt3U40H9GM++0IM0yHusd9EzlaWsbp09vsAV2DwdqS69x9RPbvE/Ne fO5subhocH76okcF/aQiQ+oj2j6LJZGBJBVigOHg+4zyzdDgKM+jp0bvDI51KQ4XfxV593OhvkS3z 3FPx0CE7l62WhWrieHyBblqvkTYgJ6dq4bsYpqxxGJOkQ47WpEUx6onH+rImWmPJbSYGhwBzTo0Mm G1Nb1qGPG+mTrSmJjDRxrwf1zjmYqQreWVSFEt26tBpSaWsgdmFuIFJpZWwgPHJpZWxAZmIuY29tP okBPgQTAQIAKAUCW5LbiAIbIwUJEswDAAYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQznneko TE3oOUEQgAsrGxjTC1bGtZyuvyQPcXclap11Ogib6rQywGYu6/Mnkbd6hbyY3wpdyQii/cas2S44N cQj8HkGv91JLVE24/Wt0gITPCH3rLVJJDGQxprHTVDs1t1RAbsbp0XTksZPCNWDGYIBo2aHDwErhI omYQ0Xluo1WBtH/UmHgirHvclsou1Ks9jyTxiPyUKRfae7GNOFiX99+ZlB27P3t8CjtSO831Ij0Ip QrfooZ21YVlUKw0Wy6Ll8EyefyrEYSh8KTm8dQj4O7xxvdg865TLeLpho5PwDRF+/mR3qi8CdGbkE c4pYZQO8UDXUN4S+pe0aTeTqlYw8rRHWF9TnvtpcNzZw== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) MIME-Version: 1.0 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 06C3C4000C X-Stat-Signature: fgzdb343uk6xeyi18ymnkdjk3hef6fe3 X-Rspam-User: X-HE-Tag: 1785522879-663179 X-HE-Meta: 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 19nnw3+7 TgxrRqb/CiRcZ3xJAGstixlrfKDq9WSMg7mM2usQNtgzfua5YFtA7WdHpVfLrqS0XQuqDFGb27TLm1PGLCBZsF9uoYBsqUeGRG4zVJQffqOPlIpGY5G5DHdy/+myUkJ26KUBDoUMqL9NMnZqrHkbnxPZf/Km0PLWqb59CNHsKZS7Sd3KIFQrcXa1Oe2mX02QZQ9XaTWYG5YI2iXhB0tXLoXwaGRknGBHH+KQWhBRC0GvzSuj+um/sW+TgwW0ZCKCNaqFGUdyguU0EQw0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 2026-07-31 at 13:33 +0100, Lorenzo Stoakes (ARM) wrote: > > =C2=A0mm/gup.c | 539 +++++++++++++++++++++++++++++++++-----------------= - > > ---- >=20 > OK it seems the message isn't really getting through... >=20 > You really have to spend at least some time filtering this LLM- > generated > stuff. >=20 I spent a fair amount of time cleaning up the code and comments. Arguably the new code is cleaner than the old code was. However, I do agree this patch is too big. That won't happen again. > Nobody's got time for walls of text and giant changes like this. >=20 I had no idea how to split it up when I made it,=C2=A0 but have found a few ways now. I've split up the patch into a series of 5 now: 1) mm/gup: convert follow_page_mask() to return a long 2) mm/gup: split follow_page_pte_commit() out of follow_page_pte() 3) mm/gup: add gup_fill_pages() and use it 4) mm/gup: return a huge page's full count from follow_page_mask() 5) mm/gup: walk multiple PTEs per follow_page_pte() call The changelogs naturally got shorter with things split up this way. > And at least use a reasonable model - sonnet isn't intended for > kernel > development is it? >=20 Sonnet 5 seems to be about on par with Opus 4.7 from last year. The difference is not that dramatic. Also, I have found that while Opus tends to make fewer=C2=A0 mistakes than Sonnet, they both produce unreadable LLM=C2=A0 output when left alone. In order for them to produce code that is at least a good starting point for editing, they need to follow rules. Once you apply the rules, Opus and Sonnet do not produce results that are all that different from each other. I just added a few new rules, so the tooling won't even let me create too-large patches any more. Whenever you see me, or somebody else, produce something wrong, either with or without an LLM, please yell at me, so I can add the proper rules to kernel-style (creation side), or review-prompts=C2=A0 (review side), so those things get caught=C2=A0 automatically in the future, and not sent to the list. --=20 All Rights Reversed.