From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 154113BB115; Wed, 2 Sep 2026 12:09:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788351000; cv=none; b=GEEttw8xOk57rnkZJtzznxKcAu06hNjFPfkjvPW1p/ARQWMmYuKETuKk4+62z06A7jwOYUodO85Urpv/t1a6YaxPJesInhCdev9WHN1vqG/6iukim1bGQdGlclGbacSy12DWUbJiLxwNtV+Acv3Mcv4JcY/IZtC2Ipc0mHQeiTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788351000; c=relaxed/simple; bh=SjfNrQGkpA3X9nEyXuOHe2XZDuXDkedMucJlksznh2E=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=oI4qRayGCLmpR8etBUjTW3w0e6ER9VlRtjVvq4w57dsU6WNU29vPf2WtebkrUqUwJHCROhhtngBKDgRkWoEURWNorlHupX4c7lp0P8N4mvWWqdKj7ehx2f0R+vCLLI/vCTHvFW+pwxuPD8yv6T6L3nSc8e68tBE+VCkzHeSEEnA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=cEIY3ZEQ; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="cEIY3ZEQ" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ADC001684; Wed, 2 Sep 2026 05:09:49 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6EBB93F8C6; Wed, 2 Sep 2026 05:09:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788350993; bh=SjfNrQGkpA3X9nEyXuOHe2XZDuXDkedMucJlksznh2E=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=cEIY3ZEQzPndMqZGE68WnJeWiFO21+8K0n+WqFQ73fBq3A6q/mhRdYUDCPlZ5vx3u sahoLhvj79mb8YbKBGmiLOsQdS3R+775Og3Cw2oaD2ZSY7XNMMHrFJjAudImdwoZ0L cRUuuDr2VsT2MPNqwrrQWn2o1AWjsTyBVCZh4qk8= From: Yeoreum Yun Date: Wed, 02 Sep 2026 13:09:36 +0100 Subject: [PATCH v4 2/3] kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20260902-fix_split-v4-2-85f03905f7b1@arm.com> References: <20260902-fix_split-v4-0-85f03905f7b1@arm.com> In-Reply-To: <20260902-fix_split-v4-0-85f03905f7b1@arm.com> To: Andrew Morton , David Hildenbrand , 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, Yeoreum Yun X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8322; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=SjfNrQGkpA3X9nEyXuOHe2XZDuXDkedMucJlksznh2E=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqmBIGChN4Z/69/a8p/NDwEvJkPUxXNn52hUppN 56OwlIXil2JAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCapgSBgAKCRBt1cPRWsUx MwckDACsk24Kt5Y9WNpyRadANFyOgMdwdOg1bJ2L7UYNeHQBnB98PQvTfy6CyJi2Vfbt5/ekH6U rxHRkn1wWDRj7MVRHYY8nIuDbJXtDw4rFRaeRlsx4YB6NnrQ6ldbLtD8/Zp3ryBAATb8S3t8t3O DBOKxQZfyVhjFNC9Dvulm38uonad/iNkoj9exikuxDbTYj3aMwA02oyxntPBsR4pfcM8f2Yl/sY arTg5AeamU2PgV4ZwBKny79p0Cx4w8EXKrrgUmn9DeVI2v+H0xrQ8s2i3kOvrpXM9E/oGZZiBSV pDC2QtuVUPgwIeH4A1eia+kH56Cvj3f6he2wwfgvk0v44SS23uVvS0dzL7r3YmRzHLa3Z1NwmkZ UHo1z/VSKAhv4iYVmxpigtH/gFcqw6cJ9NbGuh9AGLkW35ryQ74AeBz/d0veKddFM+bW9zwwRBH kyYBqLyghJG6+jiPf9wCTyA2P+Rr2ShrqqZbmMkJWAmdp4/Z6Zew3R+MnJFR/gn1jaIF0= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 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. Suggested-by: David Hildenbrand (Arm) Suggested-by: Zi Yan Reviewed-by: Zi Yan Reviewed-by: Baolin Wang Tested-by: Baolin Wang Acked-by: Lorenzo Stoakes (ARM) Signed-off-by: Yeoreum Yun --- tools/testing/selftests/mm/vm_util.c | 145 ++++++++++++++++++++++------------- tools/testing/selftests/mm/vm_util.h | 1 + 2 files changed, 92 insertions(+), 54 deletions(-) diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index 4821a3563036..dc62ce84e143 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) { int order = 0, pagesize = getpagesize(); unsigned int nr_pages = hpage_size / pagesize; int orders[MAX_NR_ORDERS], status; - int pagemap_fd, kpageflags_fd; bool ret = false; if (!nr_pages) @@ -386,15 +368,6 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages, ksft_exit_fail_msg("invalid order\n"); memset(orders, 0, sizeof(int) * MAX_NR_ORDERS); - pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); - if (pagemap_fd == -1) - ksft_exit_fail_msg("read pagemap fail\n"); - - kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY); - if (kpageflags_fd == -1) { - close(pagemap_fd); - ksft_exit_fail_msg("read kpageflags fail\n"); - } status = gather_folio_orders(addr, len, pagemap_fd, kpageflags_fd, orders, MAX_NR_ORDERS); @@ -405,48 +378,112 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages, ret = true; out: - close(pagemap_fd); - close(kpageflags_fd); return ret; } -bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) -{ - uint64_t pmd_pagesize = read_pmd_pagesize(); - - if (!pmd_pagesize) - ksft_exit_fail_msg("reading PMD pagesize failed\n"); +enum check_huge_type { + CHECK_HUGE_ANON, + CHECK_HUGE_FILE, + CHECK_HUGE_SHMEM, +}; - if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size); +static bool check_huge_type(uint64_t categories, uint64_t kpageflags, + enum check_huge_type type) +{ + const bool file = categories & PAGE_IS_FILE; + const bool swapbacked = kpageflags & KPF_SWAPBACKED; + + switch (type) { + case CHECK_HUGE_ANON: + return !file; + case CHECK_HUGE_FILE: + return file && !swapbacked; + case CHECK_HUGE_SHMEM: + return file & swapbacked; + } - return check_large_folios(addr, len, nr_hpages, hpage_size); + return false; } -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); + 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) { + close(pagemap_fd); + 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; + ret = true; + +out: + close(pagemap_fd); + close(kpageflags_fd); + return ret; } -bool check_huge_shmem(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(); - - if (!pmd_pagesize) - ksft_exit_fail_msg("reading PMD pagesize failed\n"); + return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_ANON); +} - if (hpage_size == pmd_pagesize) - return __check_pmd_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size); +bool check_huge_file(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) +{ + return __check_huge(addr, len, nr_hpages, hpage_size, CHECK_HUGE_FILE); +} - 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(addr, len, nr_hpages, hpage_size, CHECK_HUGE_SHMEM); } int64_t allocate_transhuge(void *ptr, int pagemap_fd) diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h index 9a49af88702e..f19bd17817e5 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -18,6 +18,7 @@ #define PM_SWAP BIT_ULL(62) #define PM_PRESENT BIT_ULL(63) +#define KPF_SWAPBACKED BIT_ULL(14) #define KPF_COMPOUND_HEAD BIT_ULL(15) #define KPF_COMPOUND_TAIL BIT_ULL(16) #define KPF_HWPOISON BIT_ULL(19) -- 2.43.0