From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 68F8A606A321 for ; Wed, 11 Nov 2026 08:03:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=F2wvcfZx Received: by kanga.kvack.org (Postfix) id 75FC46B05B4; Wed, 11 Nov 2026 03:03:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 710D56B05B8; Wed, 11 Nov 2026 03:03:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5DF396B05C7; Wed, 11 Nov 2026 03:03:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 27CFB6B05B4 for ; Wed, 11 Nov 2026 03:03:35 -0500 (EST) Received: from smtpin16.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id BE1101C296C for ; Wed, 11 Nov 2026 08:03:34 +0000 (UTC) X-FDA: 85422098748.16.751A2A0 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf22.hostedemail.com (Postfix) with ESMTP id 01C27C000A for ; Wed, 11 Nov 2026 08:03:32 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=F2wvcfZx; spf=pass (imf22.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794384213; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=50p9Fd2VLdoOxiYYFgHYWbsAlYcgHwGOvkLzFxjjrhY=; b=eITpRhksI25thYUSDAqzNlSmMiRZER4PVJ/SgTc7ds7MA6uYghhwGi/k4c1K0zkW8Lu9gw aBwRX4nPGBzIwHG2t7KFT2DEnR6HGdjhNRav+qS09Oq69QXr5J9avdWK8NX5ch7WPtx82l rNFRtAIyou6YTaaf1CduvVA/77OADEo= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794384213; b=BOj61+lSLqU143CG/REWUkDWSinSB8WdVxgvklWXIeEs/jlK2wVFAvSiYdG/faqTNVVLMt HLZ79zj0ZS3SCTyPVQug/hnQLcJCj2iMeTX8fy8fjwO9HghnY+XDtX7WF/mkm+AgRfD9Q/ eKejfxCeJh6aQYXpeYfD+2tn0lS57V8= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=F2wvcfZx; spf=pass (imf22.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 42D0E4043D; Wed, 11 Nov 2026 08:03:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4B841F00A05; Wed, 11 Nov 2026 08:03:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794384212; bh=50p9Fd2VLdoOxiYYFgHYWbsAlYcgHwGOvkLzFxjjrhY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=F2wvcfZx9phSjzgcW5ozLIDMz6szAIKFGeBT9PoYQRXfgljj9C5clhntjmeaYxhb9 eR5CvFmeTx86XyOvxWMXAtXxtfP3QI1Vme/NbyW1XlMxCzqxMg27TS7myeUIBYctX6 AVPVvOA36Q36FNVGg+peCAIbtOLAap71maY6pKzKSSCXEX+5AywOjERDxJYFolQzMm tROLfz86/r4xo6nmpCOFj5r58GR3OCX6c4ONJXarotASpPzasJV9vmhRdLjm7kdwo6 uAK3KX3y/MVgf8KCKS+SqVPHg5qbufqo9scCkWW+MV0P8TU+PRKWxAu0mZ7666gXPi kwFam+6T+UAiA== Message-ID: <8d73b05b-c183-4c14-9a28-7328340f9f62@kernel.org> Date: Wed, 11 Nov 2026 09:03:23 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/cma: simplify cma_declare_contiguous_multi() To: "Mike Rapoport (Microsoft)" , Andrew Morton Cc: Frank van der Linden , Ivy Lopez , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20261111-cma-multi-v2-1-4e2dddb2a2d8@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: <20261111-cma-multi-v2-1-4e2dddb2a2d8@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Stat-Signature: otbwd8b5wau1hu9s7uz7opu4y6h1dsce X-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 01C27C000A X-Rspam-User: X-HE-Tag: 1794384212-894716 X-HE-Meta: U2FsdGVkX1/anB8TNpvKJyIV31JkZdBboiTa3DfyOfXdIn/w0uWjS/mr9XoZTZHWuL7GtxcuWMJaH/JaaAbsEGGZsLg6AgEviAzuXyn6wm1oEAiGbCzpiqc43L9MbASQWYfLrF9yzsNR8z4cRy8yzF/t2c1LWMy2zJN58+oQla4s+FsdAXobSjtJ5swVlGXESzIwDEB+teqqPTxjmADk8VmXHu7bG8aRiF6i8JLlzZmJxTDbaFQ9EgJas5PWl0YIh6SgQlXkDZhqCuQZN8vrHMW817RDg3OCQbKgry8/CaIjlOHqLuNQhVpwMx9ciaphsMJtPT9Am6pOtiyn10fnKS5+pxbExBZjQ1oGhAJSdXEEKK+hMRSiwRQ0DFQLyi/HqP+j7edVkYG/G+smJQjGQ8A13WaKspTuikP8woM3I8ux+3NbugIPWanhupnCoor5GLhPDl8PCtKpQzU4AuQAU8JdiCpTrgBNF69eTCSrKMTFfXHk8gXiYwS4dw3GdoARBBMu+h/aMWdOhfuJ/DJjQy1LLcduvG0BYFA7mkSzN5Nbsg/SP17TuJn9KRpOjoK1TwFuJ4Q1w/0XAe6kECma9RxQM9PGQHseDtHOSi1c750i4kdIuikmP5CzOwpctk2HqVq3G8sJ9PmOhfULpCbCBvLE5f9QFcS3hciETHgtpP2Em6ADSS2fTZMF+K39RfaPwT8uq0vuCnVXcfUXObWzNt5YEUcVNnoZGV59sdmx0X7gYJKXhDcuxmSk5F5taJ12+AgieFZeODi3MfKbX8kuoQPj0VIz6a82uXAZKrT8Egt6xdLhhJQjEQTVv5lZ8xm45BeA882uD/Ck+ssabarMKXByKWkthCDo8EWU+JpdZC+C15pgSfeO2SuRKTcJpZTocCHqF51R3rD2Ep3uO4cXOlERduYUfKjE3IaofcY2uFiZxHkdhLSkH8ckC5RR8nu5bQDMq86iMfa8niLnuvy yEtW236u T7NfvYlrgZ+LwHVVFnTE5NZWyEeD6E+DiJnEwqbSKSbgTqhTTZUCvCY22NRRFfZIieR+cClg2z2RxHaqvilY7Zip9N1RaLPiNOtfZ4QtZiLwy2vdC1hbgJ1jljstxARZAmd5dy5Jz91kv22ORIZoRltY1B9kLMMhPV3vFSuAbdpn/8lCs+sWwwT+CLdYKu/CWowkW18Ow5QTTyNJIRtQvXXyIhUfXhLm/8LE6TfxQgZkqDLF5J7lfT/2nC8UxO3LxOsw04WcrU+mVcyc825wrESuXm9+m1e5qgCQIBsa/ixICry9jT1MxwGlam9zT2+j2aCY6Io6cnFWwqV28NtbTUyYHteahaPdzbvsH Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/10/26 23:14, Mike Rapoport (Microsoft) wrote: > When cma_declare_contiguous_multi() cannot allocate a CMA area as a > single range, it falls back to collecting a list of up to CMA_MAX_RANGES > largest free ranges above 4G, reserves them in memblock and adds them to > cma->ranges. > > The list and subsequently cma->ranges are supposed to be sorted in the > order of base addresses of the "allocated" ranges. > > This implementation has two bugs: > > * The allocation may fail even when there is enough free memory because > list_insert_sorted() sorts the list in the wrong order. > > When the list is full, the largest range is evicted rather than the > smallest, the final list is not sorted by address, and the smallest > ranges are used first. > > * the function may report success while it reserved less memory than > requested because sizesum accounts for ranges that were skipped. > > And overall it is a lot of list management and open coded range > selection for no real gain. > > Replace the current code with a loop that finds the largest free range > above 4G, reserves as much of it as needed and repeats until the entire > area is reserved or CMA_MAX_RANGES ranges are used. > > After successful alocation sort the cma->ranges by their base address. > > The new code scans free memory once for every range rather than once > for all ranges, so it is slightly slower, but it is way simpler and more > robust. > > Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested") > Reported-by: Ivy Lopez > Closes: https://lore.kernel.org/all/cover.1792032699.git.skunkolee@gmail.com > Signed-off-by: Mike Rapoport (Microsoft) > Acked-by: David Hildenbrand (Arm) > --- I'm leaving this to others (Andrew?) to pick up :) -- Cheers, David