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 EDE3A41BA9B; Wed, 26 Aug 2026 12:25:07 +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=1787747111; cv=none; b=ht91S4omENS0UJAAeStPQKRFMO+Ei7u8QrEZ1ReB6nVVPUxGLuroKM/iOr5JE3DS57l43/cAo99y1b7N+p1Ne8ZvggPbQnL8M41clDF/0PcqWHPzuCkfSeL8Yerye2VH+a5diBAMVYVd0kw272kt/7Ouv/UlFmteEb6rCer36G4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787747111; c=relaxed/simple; bh=GvQPZ0sVbuduLvQoOF9zM5jXfFX1CSDKvuBA3qmf1I8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sS9nG0AnWJzwBiWUWZaY9iM1NIYVV1C5kOItKRsnt8MKldTwXo692hO/whkW2I4hmk/VF5wGlkqXx76a1AQGKBH16+FQI82UKSzweu0qQ19MbFlSjgpMiThqOfudMNouat+wU6rZ6pSLtVg3XiJGVhke5p0A8axPuVdsHesnGy8= 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=uQ4oK8Tl; 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="uQ4oK8Tl" 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 5151E1596; Wed, 26 Aug 2026 05:25:03 -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 313D83F7D8; Wed, 26 Aug 2026 05:25:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787747107; bh=GvQPZ0sVbuduLvQoOF9zM5jXfFX1CSDKvuBA3qmf1I8=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=uQ4oK8TlYljFlraHfvdRd7Krim8N2tNZDk2qqEs+rKXm1fpcULodS+jTeipE4lc2N HMaynMo8ScJfqIL5txZ4T48K+OCtjAS3KEcQZGDAsXRBzmFRzGuKVxtYd+njkqSBBr gst23nZKEvCkrc5DdiopebD9VDTrtXgc5SVnidQA= From: Yeoreum Yun Date: Wed, 26 Aug 2026 13:24:39 +0100 Subject: [PATCH v2 1/2] kselftest: mm: prevent random failure of huge page split for khugepaged 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: 7bit Message-Id: <20260826-fix_split-v2-1-71153c7f579a@arm.com> References: <20260826-fix_split-v2-0-71153c7f579a@arm.com> In-Reply-To: <20260826-fix_split-v2-0-71153c7f579a@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=2698; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=GvQPZ0sVbuduLvQoOF9zM5jXfFX1CSDKvuBA3qmf1I8=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqjtsbim5lcCrKm1NTonGxRpo+/uWXYt6fnVqSW 2zH3AZ2+mCJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCao7bGwAKCRBt1cPRWsUx Mwl1C/9wWoLo2TBd76OtUebEOO9bmK1IDPaAImCIYUhdFcULi+QtYiaD5Dv95d2w/ur8IbUve0/ H1XJHff2OIt+Cggqmtqw128mL2F0wo+Ak2JZVW1KB0oc8lsbyMHXDswwrZb0lkBh+0IiT5Ne7YT XyWGemLyMoggKrStCYhAzx8H4sr4VrxcNAccO8j6O0VFuSW3sgpMTBNRUhhfMUQYkmwiZPMdXO8 T5/MIBY4rMwZNSg6ouXnHnjQG3F6eFj70MDP7EWR3OijfONE9hx4JIcOGtxEka+E9mizpeb26JB ehhQPMO0HbnfXVEWvsaRprxpwpckBw4s5L0mqQAqmNgcJLUIUsMEtBwToVd8lDBxN3szlymtN54 FKJ3ajlgig/fmTN3Mu/I0vBW8wfk37ly69RS90mhuL5kysqhLDErYPnXRWKTBuLBn0AGEIG0AhK /S6GF2qbFCM5LXkiORwjKDIqJLKgTnL8xI4evcfrQX8SFj+13hXf6XWXjbOXX0qRKgRc8= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 There're some random failure for split_huge_page_test when khugepaged collapses pages into pmd again which had split by the test. Prevent the khugepaged's collapses for split page by setting the mapped pmd-huge-page with MADV_NOHUGEPAGE before split. Reported-by: Kevin Brodsky Reviewed-by: Zi Yan Signed-off-by: Yeoreum Yun --- tools/testing/selftests/mm/split_huge_page_test.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 86a603692826..8f68bc94a5ca 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -180,6 +180,10 @@ static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hp if (!rss_anon_before) ksft_exit_fail_msg("No RssAnon is allocated before split\n"); + /* Prevent khugepaged from collapsing the pages. */ + if (madvise(one_page, len, MADV_NOHUGEPAGE)) + ksft_print_msg("MADV_NOHUGEPAGE failed to prevent khugepaged from collapsing pages.\n"); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, 0); @@ -227,6 +231,10 @@ static void split_pmd_thp_to_order(int order) if (!check_huge_anon(one_page, 4 * pmd_pagesize, 4, pmd_pagesize)) ksft_exit_fail_msg("No THP is allocated\n"); + /* Prevent khugepaged from collapsing the pages. */ + if (madvise(one_page, len, MADV_NOHUGEPAGE)) + ksft_print_msg("MADV_NOHUGEPAGE failed to prevent khugepaged from collapsing pages.\n"); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, order); @@ -313,6 +321,10 @@ static void split_pte_mapped_thp(void) goto out; } + /* Prevent khugepaged from collapsing the pages. */ + if (madvise(thp_area, thp_area_size, MADV_NOHUGEPAGE)) + ksft_print_msg("MADV_NOHUGEPAGE failed to prevent khugepaged from collapsing pages.\n"); + /* Split all THPs through the remapped pages. */ write_debugfs(PID_FMT, getpid(), (uint64_t)page_area, (uint64_t)page_area + page_area_size, 0); @@ -542,6 +554,9 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, ksft_test_result_skip("Pagecache folio split skipped\n"); return -2; } + /* Prevent khugepaged from collapsing the pages. */ + if (madvise(*addr, fd_size, MADV_NOHUGEPAGE)) + ksft_print_msg("MADV_NOHUGEPAGE failed to prevent khugepaged from collapsing pages.\n"); return 0; err_out_close: close(*fd); -- 2.43.0