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 ADCEE3E1CE4; Fri, 28 Aug 2026 08:11:46 +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=1787904710; cv=none; b=FlsjnlxsDn7wKZSbYM7/KP10f3G1IiSDCKdygd7QAHwSKy8SZvjpxhU2iwhjHv0ggF24RVPnvxsHWhtHn/FqFxf/cSrTt2+WWdkrNodB9XlxH2jTpY7ZeONZ5213PCT6FZXf0TTg+ss7XSnT9sY8M+BcqVxqyQCj94MqfWTX+lY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787904710; c=relaxed/simple; bh=0I8+Oez4/Fvep0PwEfY0VNcmLGz/KZXfSGanwudrUEc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=jvTBomnavGQnR2orAT2yalpZOodQ31inQ8pA5FCFxEVXGbGbg65056DuICbPHfpepDe88qPLJ7PyL7Eb2PuUER9zK1RJpDS/hN5mFIaz61UyiX461D6QiVVBrPs0Jgd8eBrHVWayOmB313IQxctQUudDt3IIKo9aprW1lpE2DuY= 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=uzaOz1/o; 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="uzaOz1/o" 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 2A3D31688; Fri, 28 Aug 2026 01:11:42 -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 794223F85F; Fri, 28 Aug 2026 01:11:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787904705; bh=0I8+Oez4/Fvep0PwEfY0VNcmLGz/KZXfSGanwudrUEc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=uzaOz1/oJlW6bR6EV5BEwzUO3ZWDtOkiX8kQqTvtQIU+8Gstt90P/EfK0V5xpWkNj 68OSVH/YFW5zcfNWR7SNP8y2tmqKwNcLcLslb9UHvON4/PDR4Qmh3g6BKvZDU9lIay TSFu6UJYE3d/Bf8dt+2bNttsDZ8Ly2mXLvKiGusM= From: Yeoreum Yun Date: Fri, 28 Aug 2026 09:11:33 +0100 Subject: [PATCH v3 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: <20260828-fix_split-v3-1-374022586a4b@arm.com> References: <20260828-fix_split-v3-0-374022586a4b@arm.com> In-Reply-To: <20260828-fix_split-v3-0-374022586a4b@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=2554; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=0I8+Oez4/Fvep0PwEfY0VNcmLGz/KZXfSGanwudrUEc=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqkUK7V9mWLeZ9zL0R9lDWbj29vfP3HZbcACkU8 XLC7wYRzBeJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCapFCuwAKCRBt1cPRWsUx MzDVDACIL2ZyqeIY0AqiOfUb3ahEZz0Rfrp9OTdH2HaozEJu//mWMJfgISeHLcX1mIMhRKl1CGl YN1+8V4wMX3xvPj1HCQPgBmLNlyLnNm5+I8ELib45qcNWBhqxgzDiK9McBcHwkmhFZ6j+PqMvUY 60h8P9i7i5Am6skrXngCeQN5hpLtBGyJwRoVy3RJ5eloa8epQpkhri6oqRNaPzXgWhzkTrrswHp PhBjE83yLQQXvHWXx78YOkBQAHHRNdp/PdQ7NPdX3e1kb5QlDWKXlB78I8pokt5viPN6R/iurR6 U70GwNWPOz0yo0l+6xjpVCw5pS/xE6tsD2usTl3/WOPbdJssbinGjAT6AHq1Nv/dscvq+SHTJre CzFNwIc8ToSlZ1p8+lU3fOjsBUz2xRNKM4S2yIkLtNHJGhW7fYEMgnu9cPzX2u8IxR9kCVa9Xjb eHgKorOz6kpR+tC+1PpeU8FdefGOWSzKZlIyJMTw5FgBrZUKP8r4bqrvxl+KZ6GUtucnc= 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..c718269a291f 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("madvise(MADV_NOHUGEPAGE) failed\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("madvise(MADV_NOHUGEPAGE) failed\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("madvise(MADV_NOHUGEPAGE) failed\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("madvise(MADV_NOHUGEPAGE) failed\n"); return 0; err_out_close: close(*fd); -- 2.43.0