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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Marek Szyprowski , Robin Murphy , Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T.J. Mercier" , =?UTF-8?Q?Christian_K=C3=B6nig?= , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Catalin Marinas , Will Deacon , Chun Ng , Thierry Reding , devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux.dev, linaro-mm-sig@lists.linaro.org, linux-trace-kernel@vger.kernel.org, Thierry Reding References: <20260807-tegra-vpr-v4-0-5510d16af89e@nvidia.com> <20260807-tegra-vpr-v4-5-5510d16af89e@nvidia.com> <3b458c02-e836-4b24-a712-57fa8dd59e45@kernel.org> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6C01640003 X-Stat-Signature: fbsn3zqbonjtxszkda15f5yb45kw48o6 X-Rspam-User: X-HE-Tag: 1786388783-571567 X-HE-Meta: U2FsdGVkX1+1AIk3FfrV0uFp7Q7lb7qIOA9GUQPlR6smEol99ctGoj3gfBnXNtwTTIReYOsLlDrtEHeDoa/2zTPQyZSFkBmKUaZ34vwW3NX/n3vrUL9CbPl/7g5i4sAhceqUApOUc6lne5tJs6V/BikLQvkSmmSy6CBH5yjDDoO5w+tsz1lTLhlace9lOONKqVZkkYxXY8DcdMPk0yMPnnA8etkSvoVuVtGMLbo9g0qyZqsnKEeoxjiJSuk5Kc/iWSfOvaI9S9YH10clUSd8EHmW4wYKDPaNwj9KtbRNtfoghgguU/ekVcm49juyLV5lHIND72wNgz692gGZAahTj81MV4DI4Sy2otAvFHHyglMox3uwv7582hiIGo+2jto0ZXM0gwjKuzcTgODcSJxMf+TgORMJMeG561n1+lohsayfpBa+CX5DXpG7Qs8de+LZAH0NqGhjyeEv8zzTNYV76nz3agiIATq05Gu3X6AAV7noCXaN71+5nBb5nlDe4qDuNRSm7tRAMFZSVEyd3akgAhp2NxQn9SD+hXrs4yHbhht8P0B6B1AVQO+f2UoHynwYrpXf+xZH7C/lzYbk7bW4pIG/cPcwWQWAfN3QM3aAHGgCOcyyyDClsxZq9pcy69QtNvCjSHg/A02/Ubnc3gWHPnMEZiYFXfzHK7J+dD613C/yJli9EeNEd5A8E/lMJay+h9HGoLPGItHyX1P78mWtrqqNYnSrFx+vYz82C3l2ZqQj2O8OmrhLezDmMI7fCAXfLUONvJLSLByOu21pwCXq4iIl1QSJJfRwLsPTbDYYNq+NL1s/PxiI605PTBCNoasVU37DMWJbR9FR8heOCeLikjY7tznfLAawwD5keAiBgEGqSFMcN1PPMD2FRzAQepLlnqWyLybZis/ecM3hSjFwKpJlG0R6emeD7m45aRrj/BOa6PMwD6zDEbGI4u9UlmkXc27qOo/gcaNign1BKW5 0qvzxB8P HpBsK4/VMp8tUMnz+AE206yGlU91KZfNeF/amriRfIavbt/xKBvD0QYbKo89oTm7ZwBKT4YvdXtiBUzwKrI2pUphkhAD6ezDyR4e9fTnKwK+Hcebhy/n+UehBX4I2za5lUmAkIIh34zoVluN2QLnKIiq15uFWr60SlDg2TgVHG4S0ql8+a5TrRj22uCieT2Wa6N8OvdAOWEXLYmkFsAUv3jiaz7MaPbVyNgH2U4rC72jNugQnd2u2hXzPAYfBRGh4nIpNVy0ZXmhNOuje+dh+ZMzMxtG34JY0XV/FNQ8fYZ35QUkyr0gfRXWhNuswMgdhZOn5Hv4ZdBpytso/LcJiQtcmoj8hFMuhjkmUbIslusE584bE/WZFlqeLYB2drxRyIkWAICCQB9WN4z5sLDYhcar7XY95xOR9fYiS Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/10/26 16:14, Thierry Reding wrote: > On Fri, Aug 07, 2026 at 06:16:06PM +0200, David Hildenbrand (Arm) wrote: >> On 8/7/26 17:54, Thierry Reding wrote: >>> From: Thierry Reding >>> >>> There is no technical reason why there should be a limited number of CMA >>> regions, so extract some code into helpers and use them to create extra >>> functions (cma_create() and cma_free()) that allow creating and freeing, >>> respectively, CMA regions dynamically at runtime. >>> >>> The static array of CMA areas cannot be replaced by dynamically created >>> areas because for many of them, allocation must not fail and some cases >>> may need to initialize them before the slab allocator is even available. >>> To account for this, keep these "early" areas in a separate list and >>> track the dynamic areas in a separate list. >>> >>> Signed-off-by: Thierry Reding >>> --- >> >> Sorry that I didn't get to reply earlier to >> >> https://lore.kernel.org/all/anS0nxAwCXGWZRl9@orome/ >> >> But I am still not convinced why we shouldn't just have a single array that >> grows dynamically. >> >> " >> After replying to T.J. I think this static array is actually a nice >> feature in a way. It allows us to more easily make a distinction between >> the regular CMA regions created from reserved-memory regions that >> represent classic carveouts, and the more versatile CMA areas that could >> be used for any purpose. >> >> Telling the two types apart could obviously also be solved using some >> kind of flag stored with the CMA area, but at this point I don't really >> see a reason why the two lists would need to be unified. >> " >> >> Really, cma_for_each_early_area() + cma_for_each_area() is just nasty. >> >> I'd strongly vote to unify unless there is a very good reason to do it >> separately. > > Marek had an interesting suggestion to extend CMA with fixed address or > range allocations, in which case we would only need a single CMA area. > If that works and is acceptable, there's not much need any longer for > cma_create()/cma_free(). That would be even better :) I didn't fully grasp what he meant, but feel free to send a prototype of the CMA changes over! -- Cheers, David