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b=Exq5Sp7zAbqNuqGv6NplKuvdr/nF4Y3VmHgtgpTLaZbU9Jx+zMmy9hxCvaaN31rRH OXAH49p1efwmh9zrCzsYf1pFWirOHcKauQ7DZ6dnzldnZcaI9rAnWgsVclPTmFxOIu wqwyFVvJv6NJhGAUPUhuQGODdeljpPlxdAz0GS6+RF7DFvAR8XjS0lo7BevGFn6/wJ mz7quZWteNXZVRLTrgNo935jT8qWHudzcdV+n3P8+A+zxNy3fWJsf+evbdLNaUs2HL QSaYI8xsJc88Guj1G+FbrjZM0Ugyi4eqJFZMlH5Wi31jHqemR78BtdXpdRcXqF0es3 ai1bGZuOgGUDg== Message-ID: <6086c386-3903-476f-ba55-bd6c21072f72@kernel.org> Date: Fri, 30 Oct 2026 09:58:05 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/hugetlb_vmemmap: Fix usemap overrun on nodes with multiple ranges To: Tim Chen , Andrew Morton , Muchun Song , Oscar Salvador Cc: Frank van der Linden , Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mohini Narkhede , Pooja Jain , Doug Nelson References: <20261029212137.3141875-1-tim.c.chen@linux.intel.com> 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: <20261029212137.3141875-1-tim.c.chen@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: E9C2BA0003 X-Stat-Signature: mo5kbed5ysqhzt9yc5sxxqkuq95kbsqx X-Rspam-User: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793350692-123161 X-HE-Meta: U2FsdGVkX1/87XbKq1ymYiyvcRrm3SLuZA5pHAqaUNLc8P6hsZOlV8JGAdN1Tg60UMDT+fMbXxk2h62ql6seS8DoIui/DP+NNjin3FLm6I2JzgtrYHJm4UBJ73nz0tFNgg75t3/4apUdm2d/Kv5XukUhD7zb16Jkd1bA+pnkXTmOoHYJ5Gyek76VI0PVTmtAceHD0smOaYrYz68OPsbNJ2G3fQlzwYdqSfARgu7lIXp7Nu4cAaqhNKyLa9uN8yJK/wf+IiVPhTJofzt1jqPPIlBqRlNHFmJNv2ayFEYl9sY7LbyWQSauoQKzRwFbuvYQtGjpYa7+IPBzNSTDGax+p9VevSqhL1ZLcsJHjTiSv5rRDNgEmZN+Jmm7UTGzrFt1tE0IjD1asHjlOMdTbAvtzqiyKBxzgA0IfAOm0ObyKw3xaeiFqrMBj/hG04yhPp1cwlKtta0fsTkcna8pmfDFd1eNO32dLHrSPCxW9dBs9j7ZQYiBriv1Z2k3vwszxNws9pI0Pjuo7xq4pbskkMv+lut4nw3BVnaZthpPKomvu5sg8wkojZgLxLIeCuoAbM39wAieEb9YeRd+FKOeGnRLlWowdC7ELqu+2VeK7NgeoM3jpFLZuQ0Xn+B+LMW5G9t+T6lc4JceHzCUq1hsAQ941Edc64ba8sB2naBuvaMON7bBwKNVD5c8LoT9s8joao4ajXkOYYcSt2zbOHagzk9eiAnEEycBycX4ELc2KwR3+CuYsWBjFjMWv1ArPFWsrIQtZQCUs6KAQ52UjDk5ShB8TwhchF1jSJZEYOiftnJfX3fsYvVWHZJUbDexE9e7j4ehCImzZCmznR0YY9dvJNgwHs2+bqVh6RSy2/RegkYx9CjeVGPFY/Rqum26Yi0IxuYFGI6628sjpkbe71XUCaPZBv9seS1dddSYQk9NQDaL7dxcv7FyUK387niVCT9Q8nujh3stZTHKeByn3JHDGj3 VcS53V7I 9faHZLhYlmynVYKTy/nL5CBBN5BQgxhwiNvsGTJQKYUATrNvUWXPAJluaRnlgh1JqFFTJzPJa+ft0a3MVIMo/CaKqT2kSKSVG4pZWGItGtyNfYT96X1DtIEMGlZLOgKYhvEfeN7izkjXltsX5J16aRr8UyY3cWVnXj8tdsRdiCbC9KoA6t1JfKpMb3+wKACqOlUtngMqNOqgFHiBfJQ3NIiHoKKIo4UJ93XX2/BH6byDI6PcHEk++tnqATVWHh4PE6tSfmYjusMP/EyrUZa2rqZLQ6I0lMnlP5dQVMAXQziOx7guuVQydcT7APChfl7id+S0lBedgWFcHEzeBZlOKo34dVjcCXJ8myy8V 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 10/29/26 22:21, Tim Chen wrote: > sparse_init_nid() allocates one usemap slot (struct mem_section_usage) > per present section in [pnum_begin, pnum_end), and > sparse_init_early_section() hands them out in order, with a BUG_ON() when > they run out. hugetlb_vmemmap_init_early(nid) however initializes the > sections of every bootmem gigantic page on the node, including pages > outside the range being initialized. If a node's memory is split into > more than one range, sparse_init() calls sparse_init_nid() once per range, > and this takes more slots than were allocated. The same happens if a > gigantic page straddles a node boundary. > > For example, with this SRAT layout every node has a small range below 4G > and a large range above 4G: > > Node 0 PXM 0 [mem 0x00000000-0x2fffffff] 768 MB (low) > Node 0 PXM 0 [mem 0x100000000-0x80cfffffff] (high) > Node 1 PXM 1 [mem 0x30000000-0x5fffffff] 768 MB (low) > ... > > In 128 MB memory sections (x86_64 SECTION_SIZE_BITS = 27), node 0's low > range is sections 0x00-0x05 (6 present sections) and its high range is > sections 0x20-0x1019. The low ranges of the other nodes are 4 or 6 > sections, all smaller than the 8 sections of a 1G page. > > Node 0's first range has 6 sections, so 6 slots. With "hugepagesz=1G > hugepages=400", hugetlb_vmemmap_init_early(0) then initializes node 0's > 1G page at 0x67c0000000 (sections 0xcf8-0xcff, in its high range), and > the 7th section hits the BUG_ON() (seen on v7.2.6): > > kernel BUG at mm/sparse.c:268! > RIP: 0010:sparse_init_early_section+0x9f/0xb0 > RAX: 0000000000200000 RBX: 0000000000000cfe RCX: 0000000000000020 > RDX: 0000000000000cfe RSI: ffd7e1d09fc00000 RDI: ff252cb28ffb3f50 > R10: ff252cb28ffb3d40 R13: 0000000000000d00 > Call Trace: > hugetlb_vmemmap_init_early+0xe1/0x140 > sparse_init_nid+0x56/0x370 > sparse_init+0x192/0x2b0 > free_area_init+0x7f/0x690 > start_kernel+0x64/0x540 > > Here RDX is the section number, and R10/RDI are 6 slots apart: the start > of the usemap buffer and its current position, which is the end. > > Pass the section range to hugetlb_vmemmap_init_early() and only pre-HVO a > page whose sections are all present and within it. Ranges are disjoint, > so each page is handled once, in its own range. > > Skipped pages are not marked HUGE_BOOTMEM_HVO. Their sections get a > regular memmap from sparse_init_nid(), and the pages are optimized later > by hugetlb_vmemmap_optimize_bootmem_folios(). > > Fixes: b1222550fbf7 ("mm/hugetlb: do pre-HVO for bootmem allocated pages") > Cc: stable@vger.kernel.org > Reported-by: Mohini Narkhede > Tested-by: Pooja Jain > Signed-off-by: Tim Chen > --- > include/linux/mmzone.h | 9 ++++++--- > mm/hugetlb_vmemmap.c | 38 ++++++++++++++++++++++++++++++++++---- > mm/hugetlb_vmemmap.h | 7 +++++-- > mm/sparse-vmemmap.c | 16 +++++++++------- > mm/sparse.c | 2 +- > 5 files changed, 55 insertions(+), 17 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 94f9c3ff54160..da17dae8b057b 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -2167,13 +2167,16 @@ static inline int preinited_vmemmap_section(const struct mem_section *section) > (section->section_mem_map & SECTION_IS_VMEMMAP_PREINIT)); > } > > -void sparse_vmemmap_init_nid_early(int nid); > +void sparse_vmemmap_init_nid_early(int nid, unsigned long pnum_begin, > + unsigned long pnum_end); > #else > static inline int preinited_vmemmap_section(const struct mem_section *section) > { > return 0; > } > -static inline void sparse_vmemmap_init_nid_early(int nid) > +static inline void sparse_vmemmap_init_nid_early(int nid, > + unsigned long pnum_begin, > + unsigned long pnum_end) Two tab indent please in all cases here that you are touching, thanks. -- Cheers, David