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From: Muchun Song In-Reply-To: <23fa4ffa-965a-da80-e8b5-73ae92dc5767@nvidia.com> Date: Wed, 14 Dec 2022 11:00:02 +0800 Cc: Sidhartha Kumar , Mike Kravetz , Matthew Wilcox , linux-kernel@vger.kernel.org, Linux Memory Management List , Andrew Morton , Muchun Song , tsahu@linux.ibm.com, David Hildenbrand Content-Transfer-Encoding: quoted-printable Message-Id: <00CBD2D1-EEDD-4171-94F4-8DCC0446F26E@linux.dev> References: <20221207223731.32784-1-sidhartha.kumar@oracle.com> <92965844-c430-8b8e-d9f1-705d7578bceb@nvidia.com> <0187f9c2-e80a-9cde-68bc-c9bdbd96b6fe@oracle.com> <2723541a-79aa-c6b5-d82c-53db76b78145@oracle.com> <36ddac45-ecd0-e2d2-e974-8c85ca503053@oracle.com> <20cc2088-b66e-28d1-a529-414e82146336@nvidia.com> <434a111c-7f1a-0018-6bd2-561cb382deea@oracle.com> <7d72778e-7305-18e9-edf4-ed55a98aa7e2@nvidia.com> <00222280-DBDD-49A3-92A5-05112359AE30@linux.dev> <23fa4ffa-965a-da80-e8b5-73ae92dc5767@nvidia.com> To: John Hubbard X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0AD18C0005 X-Stat-Signature: 7jdu7yd3hzqqtc97pcfeuizng4rww64e X-HE-Tag: 1670986840-792398 X-HE-Meta: U2FsdGVkX1/LRY5k6C6llVwmyT2u8ikVcgKsUQY+O3eLPZ3PZsY+yPv70jp7guqGsOcxYwn+adi2+wzkl+lMVj4oyMJ4OUVSx7QwU03uH7cY+O37Vq0P03NcXsIMVXiru0JnLTynlqz5cRT+rxIo8Mio2Z+4UG7CrTIMdyqYEylwr246dVUfwbPO4D/BAl3jqAeGr0WKcSeoX4kcCh3pH8oe1+5OEUu70EWcsE02o7fTtwi0iLyz3cGYYpUxSjxEoyZaRQsAE3fT86tEMjzwJd9iJ9pbxsVs+b2NXSVBpW+4juqfTmHQzsceZEgvYwG7RITETYZzWbzojTSTdEzUZFEQaeaVof1ODLpPxWB1K1kp+czPmnJTKLb11A8philxItZ9TSRhGQMSXQqWDgzohTfSKwASU4Fjf32qb0FGLVcSOouW7MPH8/FaBVf4Xa7qk1A/pqpRg4K1SMq2P6aa62oyzC8MOo/5G2m9zyU3Y5kTIYgZXSnfDzE6lH86JazN6w4v4J4idqBm9h63KE3sTVZqtgzgYlKiOGHoxzFT60WORxZw197jhx2nB3LkRvmmqhoUjihjhPfAQm8JgvSFxRXfz/B/l7Gmj0qta6kEwOOC2X74sFw1tnskWTVzuIAdrDwTeUt9vCdzIezW9rTjsbJ8ngh41wsFDNf1njgs8udVrCRS0rVdgvZet20D87bHxiDyblOLI0DQOEWcbUb9PWDo9SXu3a7qDNAS+tdUaX5RKR9iPwfLkNgNQNwXKh+Qb7Z4feonypVsW4xumJfE3xTecsCNcO3KmMm+yEtsvQgeBYIP9s2IsEXXZE0uBSdDLbmKwILWG+wABxvRtGKLhhrPU3RDl3dylqgqFK7iyTIiy7B/RQ2ruFUo8Rq7lWlmxtBwQk8ou5w= 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 Dec 10, 2022, at 05:20, John Hubbard wrote: >=20 > On 12/9/22 13:10, John Hubbard wrote: >> On 12/9/22 06:27, Muchun Song wrote: >>> =46rom you advise, I think we can remove VM_BUG_ON and handle = non-zero >>> order page, something like: >> Yes, and thanks for summarizing all the individual feedback into a >> proposed solution. >> If we go this route, then I'd suggest a little note above the = function, >> such as: >> /* >> * For non-large folios, this will have no effect, other than = possibly >> * generating a warning, if the caller attempts to set a non-zero = folio order >> * for a non-large folio. >> */ >>> static inline void folio_set_order(struct folio *folio, >>> unsigned int order) >>> { >>> if (!folio_test_large(folio)) { >>> WARN_ON(order); >=20 > Although, on second thought...I'm still a little confused about why > keeping the same name is so important? Just my personal preference. I like its simplicity. I'm not against large_folio_set_order, but suggest folio_set_order. Thanks. >=20 > A very direct approach that has more accurate naming (and therefore no > need for a strange comment explaining the behavior) would be: >=20 >=20 > static inline void large_folio_set_order(struct folio *folio, > unsigned int order) > { > if (WARN_ON_ONCE(!folio_test_large(folio))) > return; >=20 > folio->_folio_order =3D order; > #ifdef CONFIG_64BIT > folio->_folio_nr_pages =3D order ? 1U << order : 0; > #endif > } >=20 >=20 > thanks, > --=20 > John Hubbard > NVIDIA