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 B38AF477985; Mon, 21 Sep 2026 10:40:14 +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=1789987216; cv=none; b=KgJXtZDG5xdTh4usXWwRsg7EZShjuiiSl8ireJSr3+IHSBeS2kVzqRTfkhO+EHtNn7hzBTXONKxe/KvuL/PEqrsfcPGzFn4ztZvDlMg6K61XfWoQSS3e5GBqyPli3Od23lwSrwj3KfAfjAHj10bI8NfxB8TQwksrf3pnDHAZflc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789987216; c=relaxed/simple; bh=eEcKOlvZviz+OS9o/BwOzLKaVMvfJZjmjmnn1tcF9Dk=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=iQ/VXYuA/PhTIKY/PQ/oZjAYu5WerodHOSn5moohYNu2sPd+vWQZglBybQfiVbdfOQoO/Avl6tCDtwWsyhOfV9J4Wd/E/E0T3QLt/jYDC6XqScDjI/bnY2SA1Co/649TGpl+ZlR6+Uqr4ZlB/fLbG8v/b4AfL8wdF1xx7zI+Hpk= 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=cxFF/tSG; 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="cxFF/tSG" 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 80E08143D; Mon, 21 Sep 2026 03:40:10 -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 0873E3F86C; Mon, 21 Sep 2026 03:40:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789987214; bh=eEcKOlvZviz+OS9o/BwOzLKaVMvfJZjmjmnn1tcF9Dk=; h=From:Subject:Date:To:Cc:From; b=cxFF/tSGwTcESPt9tUIXLn3H7uhf+uCAjIwP7McoYDbOsQBDRzTAX7SmD6twC8pxs 1HQpTH86CFYuSSZssbRhPF3JgMYwLeueYu2ZAOR3nPTwmksvPSuWQJpuqjYi0+EprN yaqf0hKMB9bhcmXvgx7E2n44EEdKKo6YC227yiw0= From: Yeoreum Yun Subject: [PATCH v7 0/3] kselftest: mm: fix some failure of split_huge_page_test Date: Mon, 21 Sep 2026 11:40:06 +0100 Message-Id: <20260921-fix_split-v7-0-d25ec991159f@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=H4sIAIYJsWoC/23OwW7DIAwG4FepOI/JGAPOTnuPapoChRZpbSqoo k5V3n2klxGpx9/298sPUWPJsYqP3UOUOOeap0sL7m0nwmm8HKPMh5YFAlpgBJny/btef/JNJqJ BDzEQeRbt/lpiWz679l8tn3K9TeX3WT2rdfqqZVYS5OhJQzAcXEifYzm/h+ks1o5Z9457p5vTj gDRsB3Jbx39uwGwd9QcmwR6AJOcV1tneud6Z1aH6FkBGfZh62znFPXONqdsPDiFmgG6P5dl+QM 5aGsZgAEAAA== 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=4056; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=eEcKOlvZviz+OS9o/BwOzLKaVMvfJZjmjmnn1tcF9Dk=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqsQmISXAW5/OuRPdd3iSJezNDNx8zKcSXlaZRY c1lFqUQpAuJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCarEJiAAKCRBt1cPRWsUx M/pUC/4qHK7/4NifLumv1mggmsHkyq908VAh96FDwf0nywEkR8pjtcGnIf/fI2YGpxVdKtBX21L IpYF3NZsWt0nkk3Jgjr5HWuMtLJCkIJS14L6QUWdr5dRbOpSRMHny/zYlAhu2QYQk7XW4vJu9Fz LbuGyQG7Xy/41PPJAROx5cwaZbRuSj21onU4bA8HNvR4yVpU5nSSrIxshpLh6gvn37pAFaxh9q+ 1EvqLZRGrDpRRytPx1/Z3fwdAMpgkylG5vvdw0QrSYTlaMn0XYBMOkwxZ8IPbKFydq10LRd3n3X ORDsDjBBTcS5QgLiZaMIgNlv8zi0c62s+mUpIdL20LCdXgulKh1HlnW4tq3eohjnCI9jBwuooWK jL5b1SN9aOMHi0b524cXyrGyx8SfSCxkvPyazjszWXxxpiUoY6/8kELI53Y99d/sIOMsj8Yev/b TRWmuUI1HFUPvwZbhcJINU9BD9ariMxFN0VQjL1Rbbos3vi+6YOtk0Pxf2P1pBXQhPLTw= 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 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 (3): kselftest: mm: prevent random failure of huge page split for khugepaged kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper 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 | 19 +++ tools/testing/selftests/mm/uffd-common.c | 4 +- tools/testing/selftests/mm/vm_util.c | 134 ++++++++++++--------- tools/testing/selftests/mm/vm_util.h | 1 - 6 files changed, 108 insertions(+), 90 deletions(-) --- base-commit: 8d61431ed2607386b427752505379536eb634ce8 change-id: 20260820-fix_split-f44939ec44b8 Best regards, -- Sincerely, Yeoreum Yun