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 393F847B439; Mon, 21 Sep 2026 10:40:17 +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=1789987220; cv=none; b=rFIcLqmchbrjMqVD2xnpi2Mfwi/eal/ImutrNXU1/SZK7h5CZuc6246K0IzITEqDt7K5cI8D3sYQicagV/z4t+08OQthnl/kmgAghkZE1sZtCr8YsMwUQzDDRpCVhmdEZSf5cKysMMmRAO4Pa5TcHjGexeqF/L/7DIPks1KPNnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789987220; c=relaxed/simple; bh=nAZ5Nu8/Na8ryFI4SAROqdpt5betZtOhodIgZ1vFN/Q=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=dT/j2+ZSpQT2Flmhzy3JaL5XnxNFgHF57E0s3C8LP6oLaBztCrvCwDqbO/krHXsC0D4nY2bH7av9OLdFERNA0cKKLN0oQHjoHqWospgh1rx22UeT/7vImQ6nGKYOFiu66MLJFHV+Z3JbX3taS6wh2gXvsAaUEzpPKjR1Y3FtocU= 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=QSuAO5qf; 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="QSuAO5qf" 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 D9C531CE0; Mon, 21 Sep 2026 03:40:13 -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 603FB3F86C; Mon, 21 Sep 2026 03:40:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789987217; bh=nAZ5Nu8/Na8ryFI4SAROqdpt5betZtOhodIgZ1vFN/Q=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=QSuAO5qfdzbTBibtYalj0EBb9NUMvqfJDkEzxiDY4t6TCHh5A8OVXvvXEkZOXyuPN 9w/gciK3NISvJLcCd7tpD1zOypNB0ER7HlT6QXFWHKFTpl00TijpVcWh1gcEh3hUVI wbh7e19sl5OpXZCLVbJSbN2aATyAwAjJIHCEglEQ= From: Yeoreum Yun Date: Mon, 21 Sep 2026 11:40:07 +0100 Subject: [PATCH v7 1/3] 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: <20260921-fix_split-v7-1-d25ec991159f@arm.com> References: <20260921-fix_split-v7-0-d25ec991159f@arm.com> In-Reply-To: <20260921-fix_split-v7-0-d25ec991159f@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=2772; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=nAZ5Nu8/Na8ryFI4SAROqdpt5betZtOhodIgZ1vFN/Q=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqsQmJS49uY0WTGO7xDTb8XJ1buCo74SJ77Ym0b 1aLUL4K+WiJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCarEJiQAKCRBt1cPRWsUx M35vDACoT1PIgox1YUsx6mvHqeplFUSysSKEFx5zDxzyaHYhM7XddIhMZuQbuRPtxopLYkvGoXH 95U134cSKw9csvK5zS9PkJwkCcBRVzGElv0U5EkqPRtZtSRBjofPqir5KsLhAbsnaV46XfkRcGx B4xn3KQ6R0cB4Yl5hg9YygocTcfDVrRRw3wTgh2TXTKfSW4DrV9mFBH79WTXHEA0ed7GPd6MdPa hzVCq1NKEk1V6tnk8/2d5eSzTtPNpOw7jDX+CzLSNHZieAm+ofDMKVOIHhna6qEzoR4xo0/40qh wdyL+afQBouI4BC/Nli8X7BSN9xqlpFv5+D2Gk6muNYYGceRMYgeOO+6o4Jgj+NV+xJoNO1o10q /ewTkqDsTHxxeElOg+EcOTOay1fUmd65mYl+ydB3oxDHonMZCyTdO2F0sd6leullFPRteOIPS7k 6xZqRkiQK1IiUFE+DgrXm4s02W0VNYd6bYXoFvscCkU4R2Iy6EtIqd2gO/VFrWtAgy5os= 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 c01d227d7fd6d..cba327f778734 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -167,6 +167,18 @@ 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; @@ -179,6 +191,8 @@ 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); @@ -226,6 +240,8 @@ 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); @@ -274,6 +290,8 @@ 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 @@ -541,6 +559,7 @@ 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