From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CD623C43458 for ; Wed, 8 Jul 2026 15:13:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 793B26B008A; Wed, 8 Jul 2026 11:13:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 744CF6B0092; Wed, 8 Jul 2026 11:13:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 60EF46B0093; Wed, 8 Jul 2026 11:13:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 380EC6B008A for ; Wed, 8 Jul 2026 11:13:34 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id B580F1C78C2 for ; Wed, 8 Jul 2026 15:13:33 +0000 (UTC) X-FDA: 84965953506.04.48357ED Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf15.hostedemail.com (Postfix) with ESMTP id 8DA19A0013 for ; Wed, 8 Jul 2026 15:13:31 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=b172Ftkd; spf=pass (imf15.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-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783523611; b=NFrfAEIdeU1wNaBpn1aeg7Q91Uw89jyOD2Lx91G5ZWYijEytU7UYDermZI0Y825IqH5uRw 7Wmmqq1kotukBTVGUXv66T2gRKNQ/9a3eysrvJ554+MEgsHTsdufux5TuCGfGYtfqmsBPW 0yuVFPTOIXa5A0a70ZotQDmafUa66J8= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=b172Ftkd; spf=pass (imf15.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=1783523611; 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=dY3UhUcYvYikZtGBYs+3zTBokdgjfjfU+WDdt96CQOU=; b=10fjcu+n288duiOuf2JKPmlHjy0eVYDtFXUdtO0zyuaz1LG5R11c8ae1aQBHbg2pNVR+kq QzobE485OmUZg75d43noHfieFt7fdIYZzfobtkuIXOQLnuobeWuPgG1fVLhc9ANl5BaYma 1xfCcUjeHJz4fcC+KIoyCxn28nmrPnY= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 728AA42AAF; Wed, 8 Jul 2026 15:13:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E062A1F000E9; Wed, 8 Jul 2026 15:13:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783523610; bh=dY3UhUcYvYikZtGBYs+3zTBokdgjfjfU+WDdt96CQOU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=b172FtkdibBF/k8qkdVxwxVxIoxhk5PUXuLfSOQ7NIgWDpyJiB5oHp2Cwis1F1Acn mYkDzjL3ltm+oX1pUW4W7R9+SDSsMB0L3BPLtGEsHeXrhPXSyVKi/pXskqC7uwZfXR AlWQ3oFqrjN1RqIHOyB2xXwUrQ+z6f1FOJXVvv2+iWBhVti1ziuzWXnII0b2U/SVLi K07SFb5qMFexZYq8G31KTP2VkISk/Gl15rwNKkFIPURnzWsPpiZhuT+CYIrW3IsG+c msmTCOAoNIPeRx6zu14UEW7nMgVQ1eJnHAEi7px2+8RkVmtdCex1cSEYz9pCQ/+jkh 51O8uPaiOQxKA== Message-ID: Date: Wed, 8 Jul 2026 17:13:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 02/10] mm: provide free_reserved_pages(), removing x86 variant To: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Muchun Song , Oscar Salvador Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org References: <20260708-bootmem_info_part2-v1-0-156ce4986598@kernel.org> <20260708-bootmem_info_part2-v1-2-156ce4986598@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: <20260708-bootmem_info_part2-v1-2-156ce4986598@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8DA19A0013 X-Stat-Signature: 66xq6byenepkhfnj6ff1tg54uukoispb X-HE-Tag: 1783523611-458640 X-HE-Meta: U2FsdGVkX1/wxs8qjuwnDSi2/SMjIRKBDuO1AVRCEG3zWk5xmdnnixYMjnusY7D+TPbSiEavlfhby1sWDPxZrsyEcqwjA8r6Zo51W+K1aI8ep6yX/VkU8apYqhrwXYhYiaMtVojUu4S+Rg8hm05FEMJHh1KA0Ezz7ZUw+ZkFrz9ZuayjBUGlE1CKKmvq0SiD+cmM8FsNBBPYhjbUrTMZkpiWPB7QXW0yhFlwb9hUL0Rjjh/HuRa6WxHzq/yVjn/PUvNR2+e9EDm+a4Dh48pTp9cVKYwnS6pFbLrFUCXoMEGMgReNqX9rkEvVVmbexlAaRMf1IdSeTqaRhsFuuD/yiI0LwnYZZQxFzuy3cQCiABeeZ950jpkcZj9wgGgiHrec+DC+xbdLpy6/Xfvip3zQdDCDG6JSyYXMFiqNWgKX6IWldBhKoBUfCAhj4dbxjDerSbCQlWOwAC6DnoDAKPI6aijHLUAKCMcPj5CQOPYsZQfjCL3SQqFYtZJ/Tbew2F0/cSX4BM0P3DT3xQ6wIpKFUxEuNrjCCTb7f+LJgLHv4w+Rcd6ZGUjrx7heG3//CT5YfPcj+6ZJgB0ziVPKCb/NChiJq4+ca/CXKKI3EpGsaYoNq++brd/RLW2o31TdLlrQbAMGMMkxo2BOFA/g2/thBaX4+fm6Vz0j23yBYyXCeNOELzIl7+FRKMh9p67fiQFOtl1D0zfKmeY4fLtI+tbYh9PsrQYBoXfQA6e3fFCFuoYXyta8DkyayTpxs4nn6QBev1NPCVn9IjkyFFpsc0sJp5Z+rR7cBSFiM2KiCNi3XpOY10Oogdj+3q1fiA3ywnBHTfRAoXheWQi8kyjN2xJ9RZhxaIPGIWOnMlOuCSgndrpZPt0k8EajU/kQZ4cagq/4Q5fUJx0HwaPuI+OFenJrAZezjWM3r+6hBWueXsoDOHCaJab9XVUfktQGlbIY6O3i6IUeJrqbTRWfk4IzDKZ Kwj+La5p 7TMTNskuuufnhEuxNVj3nNSA52PnoRvJwnDqAVTJrMZKKIITGTlOxKfJdM2HuyAsu0pud122gBFDNWMVxBl4y+SlVlP7b8kjjWZr75qXktsjC+O4A+w+O7sqXmdtm8If8EMhdGzc3USojv0UZFmfm6iJPhHvXracRy662ri3Q1ZoOufQyxdLj1YDI49e3YiAYZwtNmsjXfM2B87TiCB1OrzETCGwGqQD7STc9BeRg934YmVtpu59NUEMyijPTiAIwwReoE75MELQ13+DPCKHnsUjmX1TlzeOO+8nGdi5hvieAvAF8TFlYMYFb6MnMQN05OjC84/suKv46F4U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/8/26 16:10, David Hildenbrand (Arm) wrote: > Let's extend free_reserved_page() in page_alloc.c to free_reserved_pages(), > dropping the custom x86 variant. The common-code variant will consume an > order, so adjust the x86 callers accordingly. > > Make free_reserved_pages() assume that we are freeing ordinary > high-order pages, just with the special "reserved" flavor. The target > use case for now is freeing vmemmap PMD pages. > > Set the refcount directly to 0 (instead of 1) and call > __free_frozen_pages(). Add some kerneldoc. Use a single > adjust_managed_page_count() call. > > Signed-off-by: David Hildenbrand (Arm) > --- > arch/x86/mm/init_64.c | 8 +------- > include/linux/mm.h | 8 ++++++-- > mm/page_alloc.c | 33 ++++++++++++++++++++++++++------- > 3 files changed, 33 insertions(+), 16 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 69e36f02a663a..320e742b0bb3f 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1000,12 +1000,6 @@ int arch_add_memory(int nid, u64 start, u64 size, > return add_pages(nid, start_pfn, nr_pages, params); > } > > -static void free_reserved_pages(struct page *page, unsigned long nr_pages) > -{ > - while (nr_pages--) > - free_reserved_page(page++); > -} > - > static void __meminit free_pagetable(struct page *page) > { > /* bootmem page has reserved flag */ > @@ -1038,7 +1032,7 @@ static void __meminit free_vmemmap_pages(struct page *page, unsigned int order, > while (nr_pages--) > put_page_bootmem(page++); > } else { > - free_reserved_pages(page, nr_pages); > + free_reserved_pages(page, order); > } > } else { > __free_pages(page, order); > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 113e1752548c2..62b261cccf16f 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3993,8 +3993,12 @@ extern unsigned long free_reserved_area(void *start, void *end, > > extern void adjust_managed_page_count(struct page *page, long count); > > -/* Free the reserved page into the buddy system, so it gets managed. */ > -void free_reserved_page(struct page *page); > +void free_reserved_pages(struct page *page, unsigned int order); > + > +static inline void free_reserved_page(struct page *page) > +{ > + free_reserved_pages(page, 0); > +} > > static inline void mark_page_reserved(struct page *page) > { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index a63733dac659e..9311d1f3793ad 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6381,15 +6381,34 @@ void adjust_managed_page_count(struct page *page, long count) > } > EXPORT_SYMBOL(adjust_managed_page_count); > > -void free_reserved_page(struct page *page) > +/** > + * free_reserved_pages - free reserved pages > + * @page: First page to free. > + * @order: The page order to free. > + * > + * Free pages allocated through memblock during boot, letting the buddy > + * manage them from now on. > + * > + * @page must be naturally aligned to the order and the order must not > + * exceed MAX_PAGE_ORDER. All pages must be reserved. > + */ > +void free_reserved_pages(struct page *page, unsigned int order) > { > - clear_page_tag_ref(page); > - ClearPageReserved(page); > - init_page_count(page); > - __free_page(page); > - adjust_managed_page_count(page, 1); > + const unsigned long nr_pages = 1UL << order; > + int i; > + > + VM_WARN_ON_ONCE(!IS_ALIGNED(page_to_pfn(page), nr_pages)); > + VM_WARN_ON_ONCE(order > MAX_PAGE_ORDER); > + > + for (i = 0; i < nr_pages; i++) { > + clear_page_tag_ref(page + i); > + ClearPageReserved(page + i); > + set_page_count(page + i, 0); Sashiko raises in reply to #4 that PFN walkers trying to grab pages could see their reference getting overridden. While that is not something we should be worrying about (or fixing in old code), I think it's best to ClearPageReserved() after set_page_count(), so someone actually trying to grab a reference would have the chance to rely on PageReserved from being a reliable indication. -- Cheers, David