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 EE7CF3F44FC for ; Sun, 20 Sep 2026 23:54:48 +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=1789948490; cv=none; b=fnvuOaly5XNib7khaydQt1g0+ipRDgfcrFBLnFfoG5H5od9WZ75QSeZ02Shh+o1aWiHuu8lbZWe9xhyA2MBg4J+ZzBh75ZRsuf9FW8xdGE9n04ProY1NGKKujzKpJ2eSZOPTEqN1dazW5vjJe9iWcmGMlDHaiIHx8WG7NZVrmtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789948490; c=relaxed/simple; bh=lmSWNNK0UTUlLRL5ufcqBnVyBkYURG/utB/0MKwHKH0=; h=Date:To:From:Subject:Message-Id; b=DyRsN+9Niy+8XFd4iylczPtxxAWVPimdgJL6uizdlOiysxZwqSj4zP8Rf1KbKEifYNmaoIEeaDq5CkeNBLD4nQZD6nfagXT0R715mDaKItRTyCrg6xXTPKASG0KH7OfyPvfLHUXFmuCCMzFMNq+bskGzAc/1J9V6yv24onuDM8A= 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=QETrmEAc; 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="QETrmEAc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 501E51F000FF; Sun, 20 Sep 2026 23:54:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789948488; bh=GPtujIiYv56Vkx1olu9nqMSrQdSJuU1Gc0dVA9Y5wrM=; h=Date:To:From:Subject; b=QETrmEAcYpkF+jzlUPj35SKmMaiih9fPbYBYUTYBGV7bPCJrfytuhmpup0tQziHu0 OTWXPy6MyRUBs5eX0CRtBOT+taW4Q1a40Q7dVe0b0XDogH5iHnMXBBqyYWM1pazNOE tXCB4M0B4d64CrEkNmnBISUVl+lY13NYN6GvhAP0= Date: Sun, 20 Sep 2026 16:54:47 -0700 To: mm-commits@vger.kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + selftests-mm-skip-collapse_compound_extreme-where-the-pmd-is-too-large.patch added to mm-new branch Message-Id: <20260920235448.501E51F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: selftests/mm: skip collapse_compound_extreme() where the PMD is too large has been added to the -mm mm-new branch. Its filename is selftests-mm-skip-collapse_compound_extreme-where-the-pmd-is-too-large.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-skip-collapse_compound_extreme-where-the-pmd-is-too-large.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Kiryl Shutsemau (Meta)" Subject: selftests/mm: skip collapse_compound_extreme() where the PMD is too large Date: Sat, 19 Sep 2026 01:24:32 +0100 collapse_compound_extreme() builds a PTE table full of distinct PTE-mapped compound pages by cycling hpage_pmd_nr fault-time THPs through mremap. It therefore needs hpage_pmd_nr PMD-order allocations in a row. That is fine at a 2M PMD (4K base pages) or a 32M one (16K). A 512M PMD -- arm64 with 64K base pages -- makes each of those an order-13 allocation, which the allocator cannot reliably hand out even once, let alone 8192 times. The failure is not a quiet one: the case calls ksft_exit_fail_msg(), so the whole binary stops and every case after it is lost. Skip the case where the PMD is larger than 32M. The MADV_COLLAPSE cases still cover PMD-order collapse on those configurations, and 4K and 16K PMDs are unaffected. Assisted-by: LLM Link: https://lore.kernel.org/20260919002451.496763-3-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) Signed-off-by: Andrew Morton Acked-by: Lorenzo Stoakes (ARM) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Baolin Wang Tested-by: Muhammad Usama Anjum Cc: Alexander Gordeev Cc: Barry Song Cc: "David Hildenbrand (arm)" Cc: Dev Jain Cc: Hugh Dickens Cc: Jason Gunthorpe Cc: kernel-team@meta.com Cc: Lance Yang Cc: Leon Romanovsky Cc: Liam Howlett Cc: Michal Hocko Cc: Nico Pache (Red Hat) Cc: Ryan Roberts Cc: Shuah Khan (Samsung OSG) Cc: Suren Baghdasaryan Cc: Usama Arif Cc: "Vlastimil Babka (SUSE)" Cc: Zi Yan --- tools/testing/selftests/mm/khugepaged.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/tools/testing/selftests/mm/khugepaged.c~selftests-mm-skip-collapse_compound_extreme-where-the-pmd-is-too-large +++ a/tools/testing/selftests/mm/khugepaged.c @@ -940,6 +940,16 @@ static void collapse_compound_extreme(st void *p; int i; + /* + * This needs hpage_pmd_nr PMD-order allocations in a row, which the + * allocator will not supply if the PMD is very large. + */ + if (hpage_pmd_size > (32UL << 20)) { + ksft_test_result_skip("%s: PMD too large for fault-time THP construction\n", + __func__); + return; + } + p = ops->setup_area(1); ksft_print_msg("Construct PTE page table full of different PTE-mapped compound pages\n"); for (i = 0; i < hpage_pmd_nr; i++) { _ Patches currently in -mm which might be from kas@kernel.org are mm-huge_memory-do-not-touch-frozen-folios-in-deferred_split_isolate.patch mm-huge_memory-dequeue-the-deferred-split-after-the-split-freeze.patch mm-huge_memory-add-folio_reset_partially_mapped.patch mm-khugepaged-drop-redundant-mm_struct-pin-in-madvise_collapse.patch mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch mm-khugepaged-rename-mthp_present_ptes-bitmap-to-eligible_ptes.patch mm-collapse-add-collapseh-for-the-collapse-interface.patch mm-collapse-state-what-a-collapse-may-do-in-the-policy.patch mm-collapse-drop-the-collapse_possible-wrapper.patch mm-collapse-name-the-per-table-scan-reset-for-what-it-resets.patch mm-collapse-separate-scanning-a-pte-table-from-collapsing-it.patch mm-collapse-open-code-collapse_single_pmd-in-its-two-callers.patch mm-collapse-work-out-the-orders-a-vma-allows-once-per-vma.patch mm-collapse-declare-the-collapse-interface-in-collapseh.patch mm-collapse-implement-madv_collapse-in-madvisec.patch selftests-mm-raise-the-khugepaged-test-case-cap.patch selftests-mm-skip-collapse_compound_extreme-where-the-pmd-is-too-large.patch selftests-mm-scale-khugepageds-collapse-wait-with-the-pmd-size.patch selftests-mm-skip-khugepaged-page-cache-cases-without-a-pmd-folio.patch selftests-mm-make-the-swap-cases-swapout-reliable.patch selftests-mm-stop-khugepaged-during-the-madv_collapse-cases.patch selftests-mm-move-is_backed_by_folio-into-vm_util.patch selftests-mm-add-folio-order-check-for-address-ranges.patch selftests-mm-add-folio-order-detection-self-check.patch selftests-mm-add-khugepaged-completion-barrier-helper.patch selftests-mm-add-order-parameterized-khugepaged-collapse-cases.patch selftests-mm-parameterize-the-mixed-source-collapse-case-by-source-order.patch selftests-mm-cover-a-shared-source-collapse-write-race.patch selftests-mm-run-every-supported-collapse-order-by-default.patch selftests-mm-check-that-one-khugepaged-pass-collapses-one-window.patch selftests-mm-add-khugepaged-race-harness.patch selftests-mm-race-the-collapse-of-windows-with-holes.patch selftests-mm-add-memory-pressure-threads-to-the-khugepaged-race-harness.patch selftests-mm-zap-whole-pte-tables-in-the-khugepaged-race-harness.patch