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 1B33A439349; Wed, 8 Jul 2026 15:27:13 +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=1783524435; cv=none; b=srd3jHAr1irnoYtASfz8utn8rpcXQHLQ62NGF83tRbRu2RXzH2l0lMGXYg+t/Bqyj0ekFdBFWb8f7xv4BLFFbQi+/++zIP3n+ZkizFWWcEIr9Y3owFYiC+l5bTsvrMIrfLGW5/AhRABh+tJXAE+A8xxQXDM/WzJO/Q7X/AhehOM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783524435; c=relaxed/simple; bh=KBOlDHzFj0lM+kCw63z4O4lR+Gdn5SZMfq0HvqPr740=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WMudVXzuhy50i1Pj3xkQlTVuiGFRIrtd8mtNVc71WhsjUWm1PFInYPhXhANQoCNeyxH+oR1UhHQBivHvCoJBP6RTMfOJEdvKvswomu10zJCOB2Tta1XEQacHEKNSC+9UaIFyfjgzIi17d8uvTKa5iiybgYP+0ge0y28uWmQDBi0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DtIuHDz4; 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="DtIuHDz4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B15E1F000E9; Wed, 8 Jul 2026 15:27:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783524433; bh=d6H66oQKu4+AFEkauauvVyBVXr6c/W/wZzKm2MLUgm4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DtIuHDz4q0OKUO3gPfm+8lKay5WivKisN0Dk+GKdB+UTpg5Pz33kxFgwvsHFF/nGL UL2svqSefT97edjrbE5kQ/YY+6/rMImYYNuijAP+WzCZRgvYz9kCq+AtPEmFScgG7Y OyForKqp9VdK7e5vGLiqgp6C4XqNeXwuh9LhUCO4iyYNg4lEzWkbmRXSq18+4jchgP 0/QEIH+VgPg4ZB4qqmh8st4tNNOlw1wwG6zFDuk2AfcEbsIdtnzC7z3JzQQL8FXW63 ec/Ojr+zZqSP4tUgyuqthZahTLLNfSGiGWtJSg1J6Pm09iivlMbrPsVPg/SvUcQCf4 4iXpqwdmoaeJQ== Message-ID: <521fbaf3-ea07-4794-8bec-ac12020e04d7@kernel.org> Date: Wed, 8 Jul 2026 17:27:05 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/10] x86/mm: stop marking page tables as MIX_SECTION_INFO 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-v1-6-156ce4986598@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-v1-6-156ce4986598@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/8/26 16:11, David Hildenbrand (Arm) wrote: > There is no good reason to mark boot page tables as MIX_SECTION_INFO: we > only free boot page tables when they are completely empty, and memory > offlining/hotunplug doesn't benefit from it in any way. > > So just stop marking page tables as MIX_SECTION_INFO. In > free_pagetable(), we can now simply free reserved pages directly. > > Signed-off-by: David Hildenbrand (Arm) > --- > arch/x86/mm/init_64.c | 59 ++------------------------------------------------- > 1 file changed, 2 insertions(+), 57 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 82bb0384b8ab0..1b17dcf781e66 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1002,21 +1002,10 @@ int arch_add_memory(int nid, u64 start, u64 size, > > static void __meminit free_pagetable(struct page *page) > { > - /* bootmem page has reserved flag */ > - if (PageReserved(page)) { > -#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE > - enum bootmem_type type = bootmem_type(page); > - > - if (type == MIX_SECTION_INFO) > - put_page_bootmem(page); > - else > - free_reserved_page(page); > -#else > + if (PageReserved(page)) > free_reserved_page(page); > -#endif > - } else { > + else > pagetable_free(page_ptdesc(page)); > - } > } > > static void __meminit free_vmemmap_pages(struct page *page, unsigned int order, > @@ -1579,50 +1568,6 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, > void register_page_bootmem_memmap(unsigned long section_nr, > struct page *start_page, unsigned long nr_pages) > { > - unsigned long addr = (unsigned long)start_page; > - unsigned long end = (unsigned long)(start_page + nr_pages); > - unsigned long next; > - pgd_t *pgd; > - p4d_t *p4d; > - pud_t *pud; > - pmd_t *pmd; > - > - for (; addr < end; addr = next) { > - pgd = pgd_offset_k(addr); > - if (pgd_none(*pgd)) { > - next = (addr + PAGE_SIZE) & PAGE_MASK; > - continue; > - } > - get_page_bootmem(section_nr, pgd_page(*pgd), MIX_SECTION_INFO); > - > - p4d = p4d_offset(pgd, addr); > - if (p4d_none(*p4d)) { > - next = (addr + PAGE_SIZE) & PAGE_MASK; > - continue; > - } > - get_page_bootmem(section_nr, p4d_page(*p4d), MIX_SECTION_INFO); > - > - pud = pud_offset(p4d, addr); > - if (pud_none(*pud)) { > - next = (addr + PAGE_SIZE) & PAGE_MASK; > - continue; > - } > - get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); > - > - pmd = pmd_offset(pud, addr); > - if (pmd_none(*pmd)) { > - next = (addr + PAGE_SIZE) & PAGE_MASK; > - continue; > - } > - > - if (!boot_cpu_has(X86_FEATURE_PSE) || !pmd_leaf(*pmd)) { > - next = (addr + PAGE_SIZE) & PAGE_MASK; > - get_page_bootmem(section_nr, pmd_page(*pmd), > - MIX_SECTION_INFO); > - } else { > - next = pmd_addr_end(addr, end); > - } > - } > } > #endif > > Sashiko being rather useless: New issues: - [Low] The patch leaves the entire bootmem_info infrastructure as dead code without removing it. -> It's not aware of other patches in the series? Surprising. Pre-existing issues: - [High] Kernel page table pages and vmemmap pages are freed to the buddy allocator before their parent entries are cleared and before the TLB is flushed, creating a dangling pointer window. -> Reported two times in previous patches and I will not fix that. -- Cheers, David