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 392F343E066; Mon, 7 Sep 2026 08:19:37 +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=1788769182; cv=none; b=S2oNdd0p7gCJzEXlfnxidlhaQ1eXgTgNb3A5yNDRUTvv5cQPyx55HRMbbb1xWjE0YzQklxk++NQ+O8GktP5QMUnV+wK0G9uuTkCLrfedvo2gExWllJBOixU6jHP77vHdTkhFyiHG8s9I5NqzFxjXQTV02zxl7QyEpJHr3gF+qlI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788769182; c=relaxed/simple; bh=v3lJLJ64R7nLhf+mDAkhjmHG3DMXCLSo7wMzBe1cAD8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=TQv15eS7vrYSECA+hrNnkhlB4HOGJsULFJI2sTOQaijZ+SHLgDo7sYqplySbr5FyEKHqalJOqOizdrilYqjypOD20cVBXu6b8gL33leQdq15i513IVxSyiGNFss9fn+bzm9d4PXqJCREEh4lyqpHcIN/EDJdIsNS1xVr1jVIDfM= 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=NnJ3qfES; 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="NnJ3qfES" 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 4FEC91A32; Mon, 7 Sep 2026 01:19:33 -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 7606B3F7D8; Mon, 7 Sep 2026 01:19:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788769177; bh=v3lJLJ64R7nLhf+mDAkhjmHG3DMXCLSo7wMzBe1cAD8=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=NnJ3qfESypCG/7s7VquBc3/XfgR2n8t9EM6vFOWw3zdnY3Tvv1TvVRy7AWYq/RyoN Et6SPOvMpe3ZL49LqM2togYdq8LBddGWT6/LbFuH90rHVB83wvFt/W5/K2mR8f15pf TdO1dh7OnueAOz8ujibMNlllM11syoCR99TQAZ/M= From: Yeoreum Yun Date: Mon, 07 Sep 2026 09:19:26 +0100 Subject: [PATCH v5 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: <20260907-fix_split-v5-1-822b810458bc@arm.com> References: <20260907-fix_split-v5-0-822b810458bc@arm.com> In-Reply-To: <20260907-fix_split-v5-0-822b810458bc@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=2716; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=v3lJLJ64R7nLhf+mDAkhjmHG3DMXCLSo7wMzBe1cAD8=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqnnOR1zCSMGM7Z/DwbyT+XNBI5kcy3peCZqhUP 2YNQyjt8cKJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCap5zkQAKCRBt1cPRWsUx M3WbC/9AcaZpg0ZOGpEKvpchDwI0fH3k+z7NXbEUuycIc7rMvohUVHUQkKblL3McQgw5FF/+Gwj g7ZRakjo6geuS38WpmXWjEajtJrLTi7f79q/FFrJYtRDLkMYAgK+/Wk5o4AxVNgJLgZS8VOSz/s FFaVd3Ia9GDrUxy+vNnqjtsPDX4RhrIP7jwhOYwDudA+Y9jGKpjRTg0G2keZDHqDq/RYE7rwgCP Ra1oLS9Pkqgk5w/zOnMZUHzosIPzkcQLP4mUdJZ6MA83STGnWVXMdr8nNDY6qCuMYB6w+mRLlQh 3Rk13SsY+AP7BxObWRUnvsXGB2pufzUXBxVABSU4illlE8knM5lUzel3OdZQPF1zfXIys8xuGWC 81hBCcuoesDSlh6KEmvxJxLIixOA/fBKim5hBl4BAsePVcBf9mY7GbTuKDIzRRafFfiwkN5zL1i KUlYSZ7B/0xkA9n/zU/QP+Cpm5N25CDxmVUZkhAxieoNxiXE7Y0oXAFHhgLHOmm/0jG8Y= 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 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 c01d227d7fd6..cba327f77873 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