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(p200300d82f22060053c7df437dc3ae39.dip0.t-ipconnect.de. [2003:d8:2f22:600:53c7:df43:7dc3:ae39]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3bb676c9426sm12398835f8f.33.2025.08.18.01.33.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Aug 2025 01:33:08 -0700 (PDT) Message-ID: Date: Mon, 18 Aug 2025 10:33:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/5] selftests/mm: reimplement is_backed_by_thp() with more precise check To: Zi Yan , Wei Yang , wang lian , Baolin Wang , linux-mm@kvack.org Cc: Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20250815023915.1394655-1-ziy@nvidia.com> <20250815023915.1394655-4-ziy@nvidia.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+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: <20250815023915.1394655-4-ziy@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: m5xi21v-JJopx-vAlr3Ec_QaUPjCGjEahG97B8bBsUo_1755505990 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1B2C5C0007 X-Stat-Signature: zn5kyro9ynaybhsx3k4xuom1o1okbtdi X-Rspam-User: X-HE-Tag: 1755505994-576937 X-HE-Meta: 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 yDhEXGC3 JXLK5C9fXo37XGBlug1/K4pr26nNGGY/ay96l6XAyevI01XbYv2okIle7NlAsr0bTSlwtr9ZcDDVbb31lN3dkzjQCkN185llWQ/x+1lCiKqjK7YMcJBN+5kgv2hXcmtXNdA9yzkGWjzNIZd7LRwpHsUGA39n+gBMdW7Dl X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 15.08.25 04:39, Zi Yan wrote: > and rename it to is_backed_by_folio(). > > is_backed_by_folio() checks if the given vaddr is backed a folio with > a given order. It does so by: > 1. getting the pfn of the vaddr; > 2. checking kpageflags of the pfn; > > if order is greater than 0: > 3. checking kpageflags of the head pfn; > 4. checking kpageflags of all tail pfns. > > pmd_order is added to split_huge_page_test.c and replaces max_order. > > Signed-off-by: Zi Yan > --- > .../selftests/mm/split_huge_page_test.c | 90 ++++++++++++++----- > tools/testing/selftests/mm/vm_util.c | 13 +++ > tools/testing/selftests/mm/vm_util.h | 4 + > 3 files changed, 84 insertions(+), 23 deletions(-) > > diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c > index 89d3dc08fe4c..80f718ca21c7 100644 > --- a/tools/testing/selftests/mm/split_huge_page_test.c > +++ b/tools/testing/selftests/mm/split_huge_page_test.c > @@ -25,6 +25,7 @@ > uint64_t pagesize; > unsigned int pageshift; > uint64_t pmd_pagesize; > +unsigned int pmd_order; > > #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages" > #define SMAP_PATH "/proc/self/smaps" > @@ -34,27 +35,71 @@ uint64_t pmd_pagesize; > #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d" > #define PATH_FMT "%s,0x%lx,0x%lx,%d" > > -#define PFN_MASK ((1UL<<55)-1) > -#define KPF_THP (1UL<<22) > #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages)) > > -static int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file) > +static int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, > + int kpageflags_fd) Could we convert this into a bool and simply return "false" on error instead of "-"? These tristate returns for a "is_*" function are a bit unfortunate. > { > - uint64_t paddr; > - uint64_t page_flags; > + unsigned long pfn_head; > + uint64_t pfn_flags; > + unsigned long pfn; > + unsigned long i; > > - if (pagemap_file) { > - pread(pagemap_file, &paddr, sizeof(paddr), > - ((long)vaddr >> pageshift) * sizeof(paddr)); > + if (pagemap_fd == -1 || kpageflags_fd == -1) > + goto fail; Should we rather expect that callers make sure these are valid? In particular, because split_pte_mapped_thp() seems to ksft_exit_fail_msg() already. > > - if (kpageflags_file) { > - pread(kpageflags_file, &page_flags, sizeof(page_flags), > - (paddr & PFN_MASK) * sizeof(page_flags)); > + pfn = pagemap_get_pfn(pagemap_fd, vaddr); Hm, if it's swapped out we would get intermittent errors, but that just seems hard to avoid. The caller could mock to avoid swapout. Memory migration is another possible problem ... But this is nothing new regarding your patch, so no need to worry for now. [...] > > +int get_pfn_flags(unsigned long pfn, int kpageflags_fd, uint64_t *flags) > +{ > + size_t count; > + > + count = pread(kpageflags_fd, flags, sizeof(*flags), > + pfn * sizeof(*flags)); > + > + if (count != sizeof(*flags)) > + return -1; > + > + return 0; > +} I would have called this function "pageflags_get()" to resemble "pagemap_get" -- Cheers David / dhildenb