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 64A403B5E15; Thu, 1 Oct 2026 21:18:07 +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=1790889488; cv=none; b=XZY54x1DGzfXi+u2ySyRkMgE3YW0U3Ys7t4cRPScp5qTTixZO/KjlUlmXoehJpmGsxs6EzrwpxjETBj18n8PsJFBtuP3BwGvg3T+V52bidFCIc1D1eEtY2p2MAt6mgrQ+Q5rjVwsQl6VGBtdVjSG/TUIqTGJ4Aj0UPS63SxXtMM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790889488; c=relaxed/simple; bh=elVZHf3wDmPU0tfGL4EH9o7DXhEwI7HvqsyNCh92HrY=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=N5wHGccWiCj+rhRWjkQAmRiD6kFh1AIdPZTauyTz3Kz+EhWHIvDvvs2EolWORdvpmhQPhrQ+RAKPgnngjQNffw870Wy5bqEnQFbJ9Ga+4SBuZkgrCNiBQrVAmVbq0oFwH+uaFqRCSxxC8SUTy116/4g2tyRfpGd28npG4JTNXX8= 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=m3xOepUI; 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="m3xOepUI" 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 35AA1497; Thu, 1 Oct 2026 14:18:03 -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 9EBB83F86F; Thu, 1 Oct 2026 14:18:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790889486; bh=elVZHf3wDmPU0tfGL4EH9o7DXhEwI7HvqsyNCh92HrY=; h=From:Subject:Date:To:Cc:From; b=m3xOepUIC8hdRxYywAiIF5vtRDekYWf/7c295Zg1wqeeeoAppiDD6ypWp0sWJe+df QIMr1y0GfX5MbVVohQrIm7xQL2sle2zYASnzUEvqQKa8tNSMNqLvrpGMiPOO3nyzKn YX0sgY3UT15ctZ5mpfB8OkFrpxs+NO5yzCV5SVsE= From: Yeoreum Yun Subject: [PATCH v9 0/4] kselftest: mm: fix some failure of split_huge_page_test Date: Thu, 01 Oct 2026 22:17:50 +0100 Message-Id: <20261001-fix_split-v9-0-0f4ba8bbdbdf@arm.com> 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 X-B4-Tracking: v=1; b=H4sIAP7NvmoC/23QQW7DIBAF0KtErOtqGAYzZNV7VFEFGDdITRxBZ KWKfPfibIKjLj/w/oy4ixJzikXsd3eR45xKms412LedCEd3/o5dGmoWCNgDI3Rjun2Vy0+6diO RVTYGIs+ivr/kWC8fXZ+Hmo+pXKf8+6ie5Xr6X8ssO+icJwVBczBh/HD59B6mk1g7ZtU6bp2qT hkCRM29I7919HQWsHVUHesRlAU9Gi+3TrfOtE6vDtGzBNLsw9b1jZPUur462cfBSFQM8LKnaRz K1pnqBtQxWCulti//wq3bzOPqgndGaTswo3u6ZVn+AFmT7f3wAQAA 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, Sarthak Sharma , Yeoreum Yun X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4504; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=elVZHf3wDmPU0tfGL4EH9o7DXhEwI7HvqsyNCh92HrY=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqvs4J9kNPaSxDmOGK6cAuegoeJSlB/nC6jvHsp 92wNFXht1OJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCar7OCQAKCRBt1cPRWsUx M1JfC/sFJzOYGspJBLB/MTgJIVH2alzwBjlzkrTRTPo4Zh0NKFh/Nx66ovKfSxWpLsll9rhdbFL i2e2ZA5IJbS57pbkyea0YnCXEwF4jQ1/K+CZf+jdzNZrZntfzLBdzx98s8m3+01437QXeyvYama BsnN9PNwvB6e+hs+q3XaLkw5YUP9e7izGSGOBSxE+luNEXaz3bBLrYx9cuGInQ8ptiAaTJ4yHEr FEE7vDFaQIJt5EJOXJ3uwmdzrM2F3Mzxx6R+rH+VOGLwu3VoJwhaViBAtbFV7KES6yvBzg7CsGb 0U2hro+rZVBHL5CqEl6P059jEzIeV3kx4/0KDH6DKdpC8RvjlG59u5EjQgTZUmBeHIIU20G/kPr JkrND+KuRU+OOne1rp7qs5Ns4lJ/uIvjxwwJgSwrmxLYVApNM7WG4f8Q4Uzrvsc8Vmo9Ob4RKRh k/ruWgOh5dFPivdwV25w/qHVHEQXTrgGmKw+nXduP/S3VOA/JGy6Q471pC1YdiwBuuvO0= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 split_huge_page_test can fail for the following reasons: 1. During the test, khugepaged may collapse previously split pages again, causing intermittent failures. 2. 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(). Moreover, a subsequent madvise(MADV_HUGEPAGE) call does not split the VMA because it already has the same advice. This causes the 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. Address these issues by applying MADV_NOHUGEPAGE after faulting in the huge page, preventing khugepaged from collapsing it again, and 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 check_huge_shmem() was required to distinguish shmem huge pages because /proc/self/smaps reports them using a dedicated “ShmemPmdMapped” entry, as opposed to “FilePmdMapped” for file-backed huge pages. Now that /proc/self/smaps is no longer used to detect huge pages and /proc/kpageflags is used instead, it is sufficient to distinguish between file-backed and anonymous pages since the ShmemPmdMapped is also kind of file-backed. Therefore, remove check_huge_shmem() and use check_huge_file() instead. This patch based on mm-unstable --- Changes in v9: - fix some typos in comment and Fixes tag. - separating huge and type checking. - add r-b tags. - Link to v8: https://lore.kernel.org/r/20260924-fix_split-v8-0-cba7359d882a@arm.com Changes in v8: - add intermediate patch for __check_pmd_huge(). - add r-b, a-b tags. - Link to v7: https://lore.kernel.org/r/20260921-fix_split-v7-0-d25ec991159f@arm.com Changes in v7: - change khugepaged's check_huge() callback. - Link to v6: https://lore.kernel.org/r/20260914-fix_split-v6-0-16ed7123800b@arm.com Changes in v6: - drop alloc_isolated_mem() patch. - remove check_huge_shmem(). - Link to v5: https://lore.kernel.org/r/20260907-fix_split-v5-0-822b810458bc@arm.com Changes in v5: - rename madv_nohuge() to disable_khugepaged(). - Link to v4: https://lore.kernel.org/r/20260902-fix_split-v4-0-85f03905f7b1@arm.com Changes in v4: - reparse commit message. - introduce alloc_isolated_mem(). - make madv_nohuge() helper according to suggestion. - Link to v3: https://lore.kernel.org/r/20260828-fix_split-v3-0-374022586a4b@arm.com Changes in v3: - change message in case of failure of madvise() with MADV_NOHUGEPAGE. - fix collapse_single_mthp (mthp_khugepaged:anon) test case failure. - Link to v2: https://lore.kernel.org/all/20260826-fix_split-v2-0-71153c7f579a@arm.com/ Changes in v2: - rebase to mm-unstable. - add message in case of failure of madvise() with MADV_NOHUGEPAGE. - fix wrong setup expected_huge in check_huge_shmem(). - Link to v1: https://lore.kernel.org/r/20260820-fix_split-v1-0-ab430c58c7cf@arm.com --- Yeoreum Yun (4): kselftest: mm: prevent random failure of huge page split for khugepaged kselftest: mm: replace usage of /proc/self/smaps for __check_pmd_huge() kselftest: mm: integrate huge page checks kselftest: mm: remove check_huge_shmem() tools/testing/selftests/mm/folio_split_race_test.c | 2 +- tools/testing/selftests/mm/khugepaged.c | 38 ++----- tools/testing/selftests/mm/split_huge_page_test.c | 16 +++ tools/testing/selftests/mm/uffd-common.c | 4 +- tools/testing/selftests/mm/vm_util.c | 113 ++++++++++++++------- tools/testing/selftests/mm/vm_util.h | 1 - 6 files changed, 100 insertions(+), 74 deletions(-) --- base-commit: e8d0f6a1b2a447d02845984fa6288787543cb03c change-id: 20260820-fix_split-f44939ec44b8 Best regards, -- Sincerely, Yeoreum Yun