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 E04534BFE8D; Thu, 24 Sep 2026 19:11:33 +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=1790277096; cv=none; b=hGpMkR065IQvvekblQ0PAcQg3NmKPXGRSVGAwdasIYodRWesSmGjQo0/dYXT/+g6jB2Nsy6+Xx+MBv37+rYZpKJ92IBCbYjrWDkSho+7oEZunjkdDNDBUB2wVoUUp9CmxlfuuXwqGC8+hnm8Kk1dD/Nk4XBD9Tx4DaiqM+8Q5ic= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790277096; c=relaxed/simple; bh=Cp04Flq0uAtUr4B5wboFRQwEJBDejnd6LVB0IHI+q3A=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=GjPHpPtzSB4QNC+FweT5nZAMpEdxRvEyRjhmp41J/QeEpMmW9sSPy4uqj0gOSrUYERQLkuF2XZbnNA1hnYBXh6Pfjrp7jcKVWArFcGHLlOiT1LX3ivOnt6HlfDE16L7SiNLovng1oQA7bQIDg9aPeCMSgcgeXr2N4ZiBW3gX1TY= 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=LBHSCsIo; 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="LBHSCsIo" 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 B4DCB1E8D; Thu, 24 Sep 2026 12:11:29 -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 DE7FC3F86F; Thu, 24 Sep 2026 12:11:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790277093; bh=Cp04Flq0uAtUr4B5wboFRQwEJBDejnd6LVB0IHI+q3A=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=LBHSCsIovix4NKw2QVz9ASL0qMoTQSCzI/HtXhZN1rnUVLy/HckTBXKlMu7oSmxhv LBhZh+4Cp2BaUS1ZvfBbrQFQ+K+r+00tZJRMnxLWbrqj+kEVcKay3Ah1vmsSGJMGN4 HDWR0b2QRs4sTRc5zU+jVPOFwW/b0XYggwieCYkc= From: Yeoreum Yun Date: Thu, 24 Sep 2026 20:11:16 +0100 Subject: [PATCH v8 1/4] 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: <20260924-fix_split-v8-1-cba7359d882a@arm.com> References: <20260924-fix_split-v8-0-cba7359d882a@arm.com> In-Reply-To: <20260924-fix_split-v8-0-cba7359d882a@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=2770; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=Cp04Flq0uAtUr4B5wboFRQwEJBDejnd6LVB0IHI+q3A=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqtXXcbujZXi+XpYIK57ZqF2h1gdqKzbbdnd1tc /WPH1DdxI+JAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCarV13AAKCRBt1cPRWsUx M8E5DAC0eBy5F+3A6LbX3CvhUrMPz514WgNRmJz6yMM1DmIcrO7HnAvnTU5LrUm1sFNxjaOxsHF Ocg7mTwtnP6axffBSXJbyo8NmCs8YY1iDpbLSeigMOg2Jw3IHcr6XYELBb0N8cGuiW4HlbAuXc1 lkNvBqOeNgKaomCSOv7Rgo+iPVkPM/z+DVpeeEh8a3j8AOuShl2vPcmlyaQRdkhNvtJNee68WcG KwudWeAIVwT1JdokYRp4/m+bMBL4O4z8laxQoacJkAfkC1vsUYdrXhPm8b+p8JEMXOBlAupxPyC bFpUiNleofMa99dxQQHXo6El1xYgUDVLHS45V05E+eoaXPlfGI8BgHJa1odRzv9J/EjiwDgv1Ft 2zUmDRpY1iHc3y9hDmCdb3H3JmH81dNXppXP82mz2a6/vYixcVbxzZUqNPj8Aey9FMiLmTfkPnD SBHwFTvyyInl2c4MuI+7rIsXwBLuZmROBR6DieFJGbn755fOeWCcjuoSImQlauiE599BQ= 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. Suggested-by: Kevin Brodsky Suggested-by: Lorenzo Stoakes (ARM) Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Zi Yan Acked-by: David Hildenbrand (Arm) Signed-off-by: Yeoreum Yun --- tools/testing/selftests/mm/split_huge_page_test.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index c5d96a4b1db3..ef4058662b91 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -108,6 +108,18 @@ static char *allocate_zero_filled_hugepage(size_t len) return result; } +static void disable_khugepaged(void *addr, size_t len) +{ + /* + * Disables khugepaged from collapsing THPs in range, existing THP + * pages remain. + */ + if (!madvise(addr, len, MADV_NOHUGEPAGE)) + return; + + ksft_exit_fail_msg("MADV_NOHUGEPAGE failed, err=%d\n", errno); +} + static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len) { unsigned long rss_anon_before, rss_anon_after; @@ -120,6 +132,8 @@ 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"); + disable_khugepaged(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, 0); @@ -167,6 +181,8 @@ 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"); + disable_khugepaged(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, order); @@ -215,6 +231,8 @@ static void split_pte_mapped_thp(void) goto out; } + disable_khugepaged(thp_area, thp_area_size); + /* * To challenge spitting code, we will mremap a single page of each * THP (page[i] of thp[i]) in the thp_area into page_area. This will @@ -482,6 +500,7 @@ 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; } + disable_khugepaged(*addr, fd_size); return 0; err_out_close: close(*fd); -- 2.43.0