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 2C34C4A1DE9 for ; Tue, 8 Sep 2026 19:50:11 +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=1788897013; cv=none; b=GMGjibDOe0SwWX9B0+1jf+GAsT9F5k1KBgMKRB/uXr5Src5BUluDB1Y6Sx6cx+IHq2dOQg84B+u9KLg62HhKse/C00M+0ALWdyN3EsxJ+WG0Bmp76QPbqQB1edaDgsXPdXF8ssTHOZgJIaINcNr+TnSGo/rFekbtltbJ7/rGnQg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788897013; c=relaxed/simple; bh=2936fruGuHSgJF+9eQCt9cSmsWy+BfRwWD37ha9JRQI=; h=Date:To:From:Subject:Message-Id; b=qDCuN2p5+Qmam1/aQl2XNJ8q2yAGIgzUpfGfyQUcAIjKNKz51/ztR7JW6OtZaie+gMZnsgvtTBt/+TJKAsYA5OuRrq811d9vrpxZg8ob7sB8xtQ5bgudh3LcnFgHJU9Y/yV7pxybwsH4fYPpo4wQoLqss3QWAb8SL0toHrNCMHE= 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=0HaJwt01; 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="0HaJwt01" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A07D81F00A3A; Tue, 8 Sep 2026 19:50:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788897011; bh=IRMhrKOlh3iCCV0sVzcWshuWE/OGrUryioWd94yPOo0=; h=Date:To:From:Subject; b=0HaJwt01zx6MS/ij/z65UW7Cjt4i8SV8cZucmk5pWr9mCe1SpUQ4qujDsDFlHlBLD O8Xhl+sdScgUjZCXkqrJtGA79hO28A0AqTlBi8SfcW4NTMnmCGGeDROc0alC0HgBXi pQ87rivc4VL4RHkg48I91YGRf7oQVogJfxYgfBk0= Date: Tue, 08 Sep 2026 12:50:11 -0700 To: mm-commits@vger.kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + selftests-mm-make-the-swap-cases-swapout-reliable.patch added to mm-new branch Message-Id: <20260908195011.A07D81F00A3A@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: make the swap cases' swapout reliable has been added to the -mm mm-new branch. Its filename is selftests-mm-make-the-swap-cases-swapout-reliable.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-make-the-swap-cases-swapout-reliable.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: make the swap cases' swapout reliable Date: Tue, 8 Sep 2026 13:50:51 +0100 collapse_swapin_single_pte() and collapse_max_ptes_swap() swap a range out and then require smaps to report exactly the count they asked for. Two things keep that count from arriving. MADV_PAGEOUT is best effort, so the count often turns up a moment late. And wait_for_scan() leaves the range eligible for collapsing, so khugepaged is still working on it. Collapsing reads the swapped-out pages back in, so the daemon empties the swap as fast as the case fills it. On arm64 with 64K pages max_ptes_swap is 1024 pages, which is 64M a step, and the case loses the race: # Swapout 1024 of 8192 pages... Fail not ok 10 collapse_max_ptes_swap Retry for up to two seconds, holding the range out of khugepaged's reach meanwhile. The collapse each case runs next restores MADV_HUGEPAGE, so only the setup is affected. If the pages still won't swap out, skip: no swap, swap too small or full, a memcg cap or busy writeback. None of that is a kernel bug. Assisted-by: LLM Link: https://lore.kernel.org/20260908125105.1510704-6-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) Reviewed-by: Muhammad Usama Anjum Tested-by: Muhammad Usama Anjum Cc: Alexander Gordeev Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: Lance Yang Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Lorenzo Stoakes (ARM) Cc: Michal Hocko Cc: Mike Rapoport (Microsoft) Cc: Ryan Roberts Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Usama Arif Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton --- tools/testing/selftests/mm/khugepaged.c | 41 +++++++++++++++------- 1 file changed, 29 insertions(+), 12 deletions(-) --- a/tools/testing/selftests/mm/khugepaged.c~selftests-mm-make-the-swap-cases-swapout-reliable +++ a/tools/testing/selftests/mm/khugepaged.c @@ -221,6 +221,29 @@ err_out: return swap; } +static bool swapout_range(void *p, unsigned long size) +{ + int i; + + /* keep khugepaged from collapsing the range and swapping it back in */ + if (madvise(p, size, MADV_NOHUGEPAGE)) + ksft_exit_fail_perror("madvise(MADV_NOHUGEPAGE)"); + + /* + * Retry several times because MADV_PAGEOUT is best effort. Sleep + * between the retries to give outstanding writeback a chance to + * finish. + */ + for (i = 0; i < 40; i++) { + if (madvise(p, size, MADV_PAGEOUT)) + ksft_exit_fail_perror("madvise(MADV_PAGEOUT)"); + if (check_swap(p, size)) + return true; + usleep(50 * 1000); + } + return false; +} + static void *alloc_mapping(int nr) { void *p; @@ -828,12 +851,10 @@ static void collapse_swapin_single_pte(s ops->fault(p, 0, hpage_pmd_size); ksft_print_msg("Swapout one page..."); - if (madvise(p, page_size, MADV_PAGEOUT)) - ksft_exit_fail_perror("madvise(MADV_PAGEOUT)"); - if (check_swap(p, page_size)) { + if (swapout_range(p, page_size)) { success("OK"); } else { - fail("Fail"); + skip("Could not swap out"); goto out; } @@ -854,12 +875,10 @@ static void collapse_max_ptes_swap(struc ops->fault(p, 0, hpage_pmd_size); ksft_print_msg("Swapout %d of %d pages...", max_ptes_swap + 1, hpage_pmd_nr); - if (madvise(p, (max_ptes_swap + 1) * page_size, MADV_PAGEOUT)) - ksft_exit_fail_perror("madvise(MADV_PAGEOUT)"); - if (check_swap(p, (max_ptes_swap + 1) * page_size)) { + if (swapout_range(p, (max_ptes_swap + 1) * page_size)) { success("OK"); } else { - fail("Fail"); + skip("Could not swap out"); goto out; } @@ -871,12 +890,10 @@ static void collapse_max_ptes_swap(struc ops->fault(p, 0, hpage_pmd_size); ksft_print_msg("Swapout %d of %d pages...", max_ptes_swap, hpage_pmd_nr); - if (madvise(p, max_ptes_swap * page_size, MADV_PAGEOUT)) - ksft_exit_fail_perror("madvise(MADV_PAGEOUT)"); - if (check_swap(p, max_ptes_swap * page_size)) { + if (swapout_range(p, max_ptes_swap * page_size)) { success("OK"); } else { - fail("Fail"); + skip("Could not swap out"); goto out; } _ 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 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