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 71132489FD0; Mon, 21 Sep 2026 15:28:06 +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=1790004488; cv=none; b=BwC/P81dGGwsq5WlJ0b73BHB76/lzXvMsdY7SzjO9lyD9R/JtNqatBuAW50a5yoFGI0YjKtqfe1tYNR57CCw2S99DjgJ3S6bqauTXzR2DhulAkkCvlpz2EGTUacmcZmcfXuO2y9eid9QOprJ1mrqYMLx14V91XP+Pn/aMY613W8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790004488; c=relaxed/simple; bh=wVcHYMUuwwHS2kJKE7fAIhuFXdPYlVJguaKZ5xDkicg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=krIqy5rgyQIs8fyXiXHQ5kwssYfwj7owIiXk2U8JaIe50rihj/wtspbe6++cYcWojXtg/aWhQDywL9OJo4d1SdyR+HS12MAn11ZF44u/445RC8v3uP4zLv9CR7H0WPcbAtaicq4rvgLzycqIjAPWzeAZAiOZ0GWDYeysz2CSHWc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M1Z45Td6; 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="M1Z45Td6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EFB01F000FF; Mon, 21 Sep 2026 15:28:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790004486; bh=K4q7WmwkmO/q0BFtHU/zrt3tXIDQ4weBhrVpkbB/RkE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=M1Z45Td6Tsh1UwdFQJQMCJDOqWa6eXAKciGI2YgR3f73yvEJiD+6J4LC4AfW8T+1b BVE4Vb8wgQqa2fHEJ9DQ/x7C6EIoJT06OMAnS4SV8MMLSGFJS6kaIxrXLB4wyA5bnN qlDTR3nxeErnD0JLgwR7rDjJj+7fN3XO038JQUb6SHa5daq2pKuzbeixgVGJGxHOCv foWqrBVJhuG1edKQyHB3xiUqD+1il/pa2s/rAgcD8yciMhGDC+8eQe8Cj55O7r82bK jpLAp3KlXx5/tptjqDeGXD39QLrL8YCrL66kM4jjPb7zpdeuqwk7L0aaN3EVMHCDBc JA0klpWeovUTg== Message-ID: <36465f31-59e2-43a5-8cd8-f8bb1844da3c@kernel.org> Date: Mon, 21 Sep 2026 17:27:57 +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 v7 2/3] kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper To: Yeoreum Yun , Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260921-fix_split-v7-0-d25ec991159f@arm.com> <20260921-fix_split-v7-2-d25ec991159f@arm.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: <20260921-fix_split-v7-2-d25ec991159f@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 9/21/26 12:40, Yeoreum Yun wrote: > Since glibc commit 321e1fc73f (“malloc: Enable 2MB THP by default on AArch64”), > glibc may call madvise(MADV_HUGEPAGE) for sufficiently large allocations > made by memalign(). > > The underlying VMA may start at a different address from the aligned > address returned by memalign(). Furthermore, a subsequent > madvise(MADV_HUGEPAGE) call does not split the VMA because the flag is > already set. > > This causes split_huge_page_test to fail because the check_huge_xxx() > helpers incorrectly require the address returned by memalign() to > match the VMA start address reported in /proc/self/smaps. > > Instead of relying on /proc/self/smaps, use /proc/self/pagemap and > /proc/kpageflags to detect huge-page mappings and large folios: > > 1. If hpage_size == pmd_pagesize, check PAGE_IS_HUGE instead of > using check_large_folios(), since only the mapping type matters. > This identifies PMD-mapped huge pages. > 2. Otherwise, use check_large_folios() to detect large folios. This > covers mTHP cases. > 3. Check the folio flags according to the type of huge page. > > Since shmem pages are also file-backed, simply check whether the page > is file-backed. > > Suggested-by: David Hildenbrand (Arm) > Suggested-by: Zi Yan Do we need a Fixes: tag? > Signed-off-by: Yeoreum Yun > --- > tools/testing/selftests/mm/vm_util.c | 137 +++++++++++++++++++++-------------- > 1 file changed, 84 insertions(+), 53 deletions(-) > > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c > index 4821a35630363..a7c5caf6925e0 100644 > --- a/tools/testing/selftests/mm/vm_util.c > +++ b/tools/testing/selftests/mm/vm_util.c > @@ -351,31 +351,13 @@ char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len) > return entry; > } > > -static bool __check_pmd_huge(void *addr, char *pattern, int nr_hpages, > - uint64_t hpage_size) > -{ > - char buffer[MAX_LINE_LENGTH]; > - uint64_t thp = -1; > - char *entry; > - > - entry = __get_smap_entry(addr, pattern, buffer, sizeof(buffer)); > - if (!entry) > - goto err_out; > - > - if (sscanf(entry, "%9" SCNu64 " kB", &thp) != 1) > - ksft_exit_fail_msg("Reading smap error\n"); > - > -err_out: > - return thp == (nr_hpages * (hpage_size >> 10)); > -} > - > -static bool check_large_folios(void *addr, size_t len, int nr_hpages, > - uint64_t hpage_size) > +static bool check_large_folios(int pagemap_fd, int kpageflags_fd, > + void *addr, size_t len, int nr_hpages, > + uint64_t hpage_size) The function used two tab indent for a reason ;) Use two tabs also in the functions you change below. [...] > > -bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) > +static bool __check_huge(void *addr, size_t len, int nr_hpages, > + uint64_t hpage_size, enum check_huge_type type) > { > - uint64_t pmd_pagesize = read_pmd_pagesize(); > + bool ret = false; > + int pagemap_fd, kpageflags_fd; > + int nr_pmd_mappings = 0; > + uint64_t pmd_pagesize, scan_mapping_size; > + uint64_t categories, kpf; > + unsigned long pfn; > + bool check_pmd_mapping, allow_nonpresent; > + char *start = addr; > + char *end = start + len; > > + pmd_pagesize = read_pmd_pagesize(); > if (!pmd_pagesize) > ksft_exit_fail_msg("reading PMD pagesize failed\n"); > > - if (hpage_size == pmd_pagesize) > - return __check_pmd_huge(addr, "FilePmdMapped:", nr_hpages, hpage_size); > + check_pmd_mapping = (hpage_size == pmd_pagesize); No need for () > + scan_mapping_size = (nr_hpages > 0) ? hpage_size : psize(); > + /* Some mTHP tests check a partially populated PMD-sized range. */ > + allow_nonpresent = (uint64_t)nr_hpages * hpage_size < len; > > - return check_large_folios(addr, len, nr_hpages, hpage_size); > + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); > + if (pagemap_fd < 0) > + ksft_exit_fail_msg("open pagemap fail\n"); > + > + kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY); > + if (kpageflags_fd < 0) > + ksft_exit_fail_msg("open kpageflags fail\n"); > + > + if (!check_pmd_mapping && > + !check_large_folios(pagemap_fd, kpageflags_fd, > + addr, len, nr_hpages, hpage_size)) > + goto out; > + > + for (; start < end; start += scan_mapping_size) { > + categories = pagemap_scan_get_categories(pagemap_fd, start); > + pfn = pagemap_get_pfn(pagemap_fd, start); > + if (pfn == -1UL) { > + if (!allow_nonpresent) > + goto out; > + else > + continue; > + } > + if (pageflags_get(pfn, kpageflags_fd, &kpf)) > + ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno)); > + if (check_pmd_mapping && (categories & PAGE_IS_HUGE)) > + nr_pmd_mappings++; > + if (kpf & KPF_COMPOUND_TAIL) > + continue; > + if (!check_huge_type(categories, kpf, type)) > + goto out; > + } > + > + if (check_pmd_mapping && (nr_pmd_mappings != nr_hpages)) > + goto out; There is way too much happening here, which makes this rather hard to review. Why can't we just focus on the smaps change for now? I.e., something like the following (untested) diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index 4821a35630363..5d348d6985026 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -351,24 +351,6 @@ char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len) return entry; } -static bool __check_pmd_huge(void *addr, char *pattern, int nr_hpages, - uint64_t hpage_size) -{ - char buffer[MAX_LINE_LENGTH]; - uint64_t thp = -1; - char *entry; - - entry = __get_smap_entry(addr, pattern, buffer, sizeof(buffer)); - if (!entry) - goto err_out; - - if (sscanf(entry, "%9" SCNu64 " kB", &thp) != 1) - ksft_exit_fail_msg("Reading smap error\n"); - -err_out: - return thp == (nr_hpages * (hpage_size >> 10)); -} - static bool check_large_folios(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) { @@ -410,20 +392,34 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages, return ret; } -bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) +static bool __check_pmds(void *start, size_t len, int expected_file_pmds, + int expected_anon_pmds, uint64_t pmd_pagesize) { - uint64_t pmd_pagesize = read_pmd_pagesize(); + int found_anon_pmds = 0, found_file_pmds = 0; + int pagemap_fd; + void *addr; - if (!pmd_pagesize) - ksft_exit_fail_msg("reading PMD pagesize failed\n"); + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); + if (pagemap_fd < 0) + ksft_exit_fail_msg("open pagemap fail\n"); - if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size); + for (addr = start; addr < start + len; addr += pmd_pagesize) { + const uint64_t categories = pagemap_scan_get_categories(pagemap_fd, addr); - return check_large_folios(addr, len, nr_hpages, hpage_size); + if (!(categories & PAGE_IS_HUGE)) + continue; + if (categories & PAGE_IS_FILE) + found_file_pmds++; + else + found_anon_pmds++; + } + + close(pagemap_fd); + return found_anon_pmds == expected_anon_pmds && + found_file_pmds == expected_file_pmds; } -bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) +bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) { uint64_t pmd_pagesize = read_pmd_pagesize(); @@ -431,12 +427,12 @@ bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) ksft_exit_fail_msg("reading PMD pagesize failed\n"); if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, "FilePmdMapped:", nr_hpages, hpage_size); + return __check_pmds(addr, len, 0, nr_hpages, pmd_pagesize); return check_large_folios(addr, len, nr_hpages, hpage_size); } -bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) +bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) { uint64_t pmd_pagesize = read_pmd_pagesize(); @@ -444,11 +440,16 @@ bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size ksft_exit_fail_msg("reading PMD pagesize failed\n"); if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size); + return __check_pmds(addr, len, nr_hpages, 0, pmd_pagesize); return check_large_folios(addr, len, nr_hpages, hpage_size); } +bool check_huge_shmem(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) +{ + return check_huge_file(addr, len, nr_hpages, hpage_size); +} + int64_t allocate_transhuge(void *ptr, int pagemap_fd) { uint64_t ent[2]; -- 2.43.0 -- Cheers, David