From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBB76545284 for ; Wed, 9 Sep 2026 13:39:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788961179; cv=none; b=TShRDh38rIyt1dKa6wyPk9x/hxFRhl/KTSxTZCKPm7lgkNevsKdTxI2xGWjtfTiI6rmrC/ZePeqd4ByOxBmYcd4Z8p7fSGpwFUmDcITObs9EDFpuCHhGFhC9P//O9WHKrHpKzPDWeMzB9PN//XHHjonO+H+IUIYZLO0fKCTPUVw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788961179; c=relaxed/simple; bh=ADJn4yusT2jkKciSg4N6YALdMSIALstYrgLb9kA/qr4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=roexqpgbDL0g4f1ARSKaqoAaDUrz89w4gKZPe5LmC12fPCwLDcPTlTBqG6I2XXPfLRHHIJgyyoKzUGPo36JRJmNwp0L0FS7zTPb68tOPQkdTe9Rahfek+uU+jP8g9YJHqGw2blTYuE8YmI9nHvo3u93zBR+4H3XS0SwXcTd8yBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aLPoNRcJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aLPoNRcJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE4BA1F00A3A; Wed, 9 Sep 2026 13:39:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788961178; bh=2iP4r/Esf2pGXwRFwOfaFPtixVlzXtak19L1ZuCehHI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aLPoNRcJrIUL+1yqxoKS9+amtbp4r91seb6cACR5mTIDhpdc6wojfjfrTvCip5Glu tA7h5LfhL6E3cdvU+mtaMv36LFxeTn7cXy5YIvtuhuR1FyBs64qdeFCrBDIAu1eh/C IH0pR+3/vxzT3FMaHyneR1NIdYVAntqyeB1fpYiYh4QZq5ZGWsgi+avt6V6DFgbJzC QPOVxXnt+bRM9lkBejCdDiKLSUUL+oWMULfrXtNJ+Yhd6QxmbozNFQr9msKbjaC/Sy iM6lNn/cbUanuJCiCnm8KC0R3c923oFV9IZGvBgvEuaAxXL6jSzWrlNzAACXjnRwiw V/LNo3CKTkobQ== Message-ID: Date: Wed, 9 Sep 2026 15:39:33 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 10/17] mm/hugetlb: switch HugeTLB to section-based vmemmap optimization To: Muchun Song Cc: Muchun Song , Andrew Morton , Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Michal Hocko , David Laight , "Liam R . Howlett" , Suren Baghdasaryan , Qi Zheng , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260825084608.47437-1-songmuchun@bytedance.com> <20260825084608.47437-11-songmuchun@bytedance.com> <67dc7ac8-b39d-4354-8cbf-f2a1c3a369ee@kernel.org> <82CAF33D-2482-4E8B-826D-8AF5E6FF8866@linux.dev> 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: <82CAF33D-2482-4E8B-826D-8AF5E6FF8866@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/9/26 15:08, Muchun Song wrote: > > >> On Sep 9, 2026, at 17:58, David Hildenbrand (Arm) wrote: >> >> On 8/25/26 10:46, Muchun Song wrote: >>> HugeTLB bootmem vmemmap optimization still carries its own early setup >>> path, including pre-populating optimized mappings before the generic >>> sparse-vmemmap code runs. >>> >>> Now that the section-based vmemmap optimization can derive HugeTLB >>> vmemmap deduplication from section metadata, HugeTLB only needs to mark >>> the bootmem huge page range with the appropriate order. The generic >>> sparse-vmemmap population path can then allocate and map the shared tail >>> vmemmap pages without any HugeTLB-specific early population code. >>> >>> Do that by setting the section order when a bootmem huge page is >>> allocated and dropping the dedicated pre-HVO helpers and related >>> special-casing. >>> >>> This removes duplicate early setup logic and switches HugeTLB to the >>> section-based vmemmap optimization path. >>> >>> Signed-off-by: Muchun Song >>> Acked-by: Mike Rapoport (Microsoft) >>> --- >>> v3: >>> - Use the order-based helper for the bootmem vmemmap-optimized check >>> >>> v2: >>> - Collect Acked-by from Mike Rapoport >>> --- >>> include/linux/hugetlb.h | 1 - >>> include/linux/mm.h | 3 -- >>> mm/hugetlb.c | 30 ++------------ >>> mm/hugetlb_vmemmap.c | 90 +++-------------------------------------- >>> mm/hugetlb_vmemmap.h | 14 +++---- >>> mm/sparse-vmemmap.c | 31 -------------- >>> mm/sparse.h | 27 +++++++++++++ >>> 7 files changed, 42 insertions(+), 154 deletions(-) >> >> Nice cleanup. >> >>> >>> diff --git a/mm/sparse.h b/mm/sparse.h >>> index e4617f9c8876..049272aba84e 100644 >>> --- a/mm/sparse.h >>> +++ b/mm/sparse.h >>> @@ -16,6 +16,24 @@ static inline unsigned int section_order(const struct mem_section *section) >>> return section->order; >>> } >>> >>> +static inline void section_set_order(struct mem_section *section, unsigned int order) >>> +{ >>> + VM_WARN_ON(section_order(section) && order && section_order(section) != order); >>> + section->order = order; >> >> As raised previously "section order" is entirely unclear. If this is a compound >> page order we should spell that out. > > But I also have another question. Should I also rename the helper name, > like section_set_compound_order? or it is enough to just renaming > the field name? Rename the helpers please. A memory section has a size (which is a power of two / order). The page order used inside the section should be clearly separated. BTW, I didn't mention it yet, but I really enjoy this cleanup. -- Cheers, David