From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 593914279E0 for ; Wed, 23 Sep 2026 18:44:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790189103; cv=none; b=SrnDHVW/BYfKo4jeEuT4FErC8zhp0iAI/Q5Ha+wh1++V4C4UoIPh9VD9Zi5RSoYocWOoYlF2y3ggt+ax0JNHzbt9Kyp76v4XuJPSpAQ+nKkbyE1Kg5XVJZGpyaUUOG3fapkw/i4j0GJn4erhYvUzi0pfLfbSoLI+Ku3zEwoDj2s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790189103; c=relaxed/simple; bh=yHtA0vLXN+IJb7jy8delhkkjzwgZr6FjetlSuIct9ro=; h=Date:To:From:Subject:Message-Id; b=aEU5tXVYaTPEE+E1c975bPEKctBuGidjYPldvNUr7O+AyoHAz11NH2Vbu0Umsenaw+sU5Ire+NbBQLuXKo1v/L4yTKyMeZ1e3oBq5vOJxxexQS1GdcVeg+fvd5pomjMwq4rzzy8LPeHEt+ZPvqZvEAuGvxM5EH5uAneXFGO8sT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=qOG3hvU0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="qOG3hvU0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 875CA1F00893; Wed, 23 Sep 2026 18:44:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790189093; bh=8+x5eLk+2dP6r49jlubhDu9o4sjc/PovWT6m/j3aC2c=; h=Date:To:From:Subject; b=qOG3hvU0+GtGKi2vDj0zOFQ+DBbOFS+KCdzhd6QmF/tr7QF4jgp2bBrlmHS+vUuUr PN4rI7/2smeoKb8cNG54ex6GSE66w7/A/5WFUPt4qmn/7RY61NUqRxl1HWr1tSlavq clolw9x/sdsxG9FeIsBf5GVoj7a26jXUjBllxTMU= Date: Wed, 23 Sep 2026 11:44:53 -0700 To: mm-commits@vger.kernel.org,yeoreum.yun@arm.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] kselftest-mm-return-fail-when-child-test-result-is-fail-in-khugepaged.patch removed from -mm tree Message-Id: <20260923184453.875CA1F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: kselftest: mm: return fail when child test result is fail in khugepaged has been removed from the -mm tree. Its filename was kselftest-mm-return-fail-when-child-test-result-is-fail-in-khugepaged.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Yeoreum Yun Subject: kselftest: mm: return fail when child test result is fail in khugepaged Date: Mon, 21 Sep 2026 11:35:01 +0100 Patch series "kselftest: mm: fix intermittent failure khugepaged test", v2. There are intermittent failures in collapse_max_ptes_swap() and collapse_max_ptes_shared() when using the khugepaged_context: # Run test: collapse_max_ptes_shared (khugepaged:anon) # Allocate huge page... OK # Share huge page over fork()... OK # Trigger CoW on page 1023 of 2048... OK # Maybe collapse with max_ptes_shared exceeded.... OK # Trigger CoW on page 1024 of 2048... Fail Bail out! Unexpected huge page # Planned tests != run tests (26 != 23) # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 # Run test: collapse_max_ptes_swap (khugepaged:anon) # Swapout 257 of 2048 pages... OK # Maybe collapse with max_ptes_swap exceeded.... OK # Swapout 256 of 2048 pages... OK Bail out! Unexpected huge page # Planned tests != run tests (26 != 17) # Totals: pass:17 fail:0 xfail:0 xpass:0 skip:0 error:0 This happens because khugepaged may collapse the pages before wait_for_scan() is called, causing a sanity check that expects uncollapsed pages to fail. For example, in collapse_max_ptes_swap(), after faulting the pages back in and paging out up to max_ptes_swap pages, khugepaged may collapse them again before c->collapse() is called. To prevent this, mark the VMA with MADV_NOHUGEPAGE after it has been collapsed by wait_for_scan() for anon. This prevents khugepaged from collapsing it again before c->collapse() is called. Also, fix false-positive results when a child process fails in tests such as collapse_fork*() or collapse_max_ptes_shared(): # ------------------------- # running ./khugepaged -s 2 # ------------------------- # # Run test: collapse_max_ptes_shared (khugepaged:anon) # Allocate huge page... OK # Share huge page over fork()... OK # Trigger CoW on page 1023 of 2048... OK # Maybe collapse with max_ptes_shared exceeded.... OK # Trigger CoW on page 1024 of 2048... Fail Bail out! Unexpected huge page # Planned tests != run tests (26 != 23) # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 // child failed. # Check if parent still has huge page... OK // parent hpage success ok 24 collapse_max_ptes_shared // considered as success ... # Totals: pass:26 fail:0 xfail:0 xpass:0 skip:0 error:0 This failure was observed on NVIDIA Spark with 16KB page. This patch (of 2): Although the child process in collapse_fork*() or collapse_max_ptes_shared() reports `KSFT_FAIL`, the result is ignored because the test only checks whether the parent's page was collapsed into a huge page. As a result, the test is considered successful whenever the parent's page is a huge page, even if the child test fails, as shown below: # # Run test: collapse_max_ptes_shared (khugepaged:anon) # Allocate huge page... OK # Share huge page over fork()... OK # Trigger CoW on page 1023 of 2048... OK # Maybe collapse with max_ptes_shared exceeded.... OK # Trigger CoW on page 1024 of 2048... Fail Bail out! Unexpected huge page # Planned tests != run tests (26 != 23) # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 // child failed. # Check if parent still has huge page... OK // parent hpage success ok 24 collapse_max_ptes_shared // considered as success ... # Totals: pass:26 fail:0 xfail:0 xpass:0 skip:0 error:0 To address this, propagate the child's failure and skip the subsequent check in the parent. Link: https://lore.kernel.org/20260921-fix_khugepagd_fail-v2-0-3c2877beef61@arm.com Link: https://lore.kernel.org/20260921-fix_khugepagd_fail-v2-1-3c2877beef61@arm.com Signed-off-by: Yeoreum Yun Signed-off-by: Andrew Morton Reviewed-by: Baolin Wang Cc: Zi Yan Cc: Liam Howlett Cc: Nico Pache (Red Hat) Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes (ARM) Cc: "Vlastimil Babka (SUSE)" Cc: "Mike Rapoport (IBM)" Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: David Hildenbrand (ARM) Cc: Shuah Khan (Samsung OSG) --- tools/testing/selftests/mm/khugepaged.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/tools/testing/selftests/mm/khugepaged.c~kselftest-mm-return-fail-when-child-test-result-is-fail-in-khugepaged +++ a/tools/testing/selftests/mm/khugepaged.c @@ -1053,6 +1053,8 @@ static void collapse_fork(struct collaps wait(&wstatus); exit_status = WEXITSTATUS(wstatus); + if (exit_status == KSFT_FAIL) + goto out; ksft_print_msg("Check if parent still has small page..."); if (ops->check_huge(p, hpage_pmd_size, 0, hpage_pmd_size)) @@ -1060,6 +1062,7 @@ static void collapse_fork(struct collaps else fail("Fail"); validate_memory(p, 0, page_size); +out: ops->cleanup_area(p, hpage_pmd_size); ksft_test_result_report(exit_status, "%s\n", __func__); } @@ -1100,6 +1103,8 @@ static void collapse_fork_compound(struc wait(&wstatus); exit_status = WEXITSTATUS(wstatus); + if (exit_status == KSFT_FAIL) + goto out; ksft_print_msg("Check if parent still has huge page..."); if (ops->check_huge(p, hpage_pmd_size, 1, hpage_pmd_size)) @@ -1107,6 +1112,7 @@ static void collapse_fork_compound(struc else fail("Fail"); validate_memory(p, 0, hpage_pmd_size); +out: ops->cleanup_area(p, hpage_pmd_size); ksft_test_result_report(exit_status, "%s\n", __func__); } @@ -1158,6 +1164,8 @@ static void collapse_max_ptes_shared(str wait(&wstatus); exit_status = WEXITSTATUS(wstatus); + if (exit_status == KSFT_FAIL) + goto out; ksft_print_msg("Check if parent still has huge page..."); if (ops->check_huge(p, hpage_pmd_size, 1, hpage_pmd_size)) @@ -1165,6 +1173,7 @@ static void collapse_max_ptes_shared(str else fail("Fail"); validate_memory(p, 0, hpage_pmd_size); +out: ops->cleanup_area(p, hpage_pmd_size); ksft_test_result_report(exit_status, "%s\n", __func__); } _ Patches currently in -mm which might be from yeoreum.yun@arm.com are kselftest-mm-fix-potential-failure-for-merged-vma-in-guard-regions.patch kselftest-mm-remove-exclusion-of-building-soft-dirty-test-in-arm64.patch kselftest-mm-fix-intermittent-failure-khugepaged-test.patch