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 699B848E0FA for ; Tue, 8 Sep 2026 19:50:27 +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=1788897031; cv=none; b=VuWvVc53PF5iU+2l3MyhiqjN4alec62dEm9dP0fCI4Qw/hin5din2nBUkaxftFi9qiVi3goPex8TLPmCToG9Doc7nSa1VpgNLnRgdg1p3rc/9Tp61M3RDYfZgL+WlajgM+J0hKFHIqvkrAOcpBMTs3anvBjm2A9TA1x+GGDEKL4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788897031; c=relaxed/simple; bh=hlZFCvCW/Q/eHJJfH1dFi/9X1bRkT/rWKmtfsRj1ZuY=; h=Date:To:From:Subject:Message-Id; b=kgsn0A4KXYDzd8lAnG4oXFl6GnIcjT8Wu1IBas8SgY//4OqrjM9BTY6CnMiKAjZr+IqLlHslUUJWux0GVxigVnmmEfQ9uiIQB4i4CXVnnQWmxDUN6MoaPeIKvHsj09hMYLP6K7YrGivS6zw2HtMqZCpFujLeNyE5tfdd6ba6ygM= 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=h0pOZlPr; 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="h0pOZlPr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A9FA1F00A3D; Tue, 8 Sep 2026 19:50:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788897027; bh=B0PiLlPHC+CsNcqWOC7bEstHbj4QXbePx7bHmXtxnsQ=; h=Date:To:From:Subject; b=h0pOZlPreHa0EByCJucW1igJGdrZtaoVcFRhpw+nO7oMo0G+maIKksgpTemyn4zM9 HaXY8AZ1iCOFy6yT1GKzu5hiaizrgFe2fMRBPRaWyUpL48lI4k98mTp5nXjU0chaSH mIiO+fR7c8OlhDEjiozbR7qzj804PY3WmevRDw0A= Date: Tue, 08 Sep 2026 12:50:26 -0700 To: mm-commits@vger.kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + selftests-mm-add-khugepaged-completion-barrier-helper.patch added to mm-new branch Message-Id: <20260908195027.2A9FA1F00A3D@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: add khugepaged completion barrier helper has been added to the -mm mm-new branch. Its filename is selftests-mm-add-khugepaged-completion-barrier-helper.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-add-khugepaged-completion-barrier-helper.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: add khugepaged completion barrier helper Date: Tue, 8 Sep 2026 13:50:56 +0100 A khugepaged test has to tell "not collapsed" from "not scanned yet", and nothing in the selftests can. wait_for_scan() in khugepaged.c comes closest: it polls full_scans until the counter has advanced by two, since the pass in progress may already have passed the test's mm. But it only returns in time if scan_sleep_millisecs happens to be short, and it is private to that one test. Add khugepaged_full_pass() to hugepage_settings, built on the same advance-by-two wait but driven through sysfs: a store to scan_sleep_millisecs wakes the daemon, so the barrier completes whatever the scan cadence. A store made while the daemon is scanning rather than sleeping is lost, so the helper keeps storing until the pass lands. One wake completes one pass only if pages_to_scan covers every mm on the list, so callers need it large. Settings pushes must not start passes of their own. A store to either sleep knob wakes the daemon, so thp_write_settings() now writes a khugepaged knob only when its value changes. Assisted-by: LLM Link: https://lore.kernel.org/20260908125105.1510704-11-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) 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/lib/mm/hugepage_settings.c | 60 ++++++++++++++++++++++++----- tools/lib/mm/hugepage_settings.h | 2 2 files changed, 53 insertions(+), 9 deletions(-) --- a/tools/lib/mm/hugepage_settings.c~selftests-mm-add-khugepaged-completion-barrier-helper +++ a/tools/lib/mm/hugepage_settings.c @@ -217,6 +217,13 @@ void thp_read_settings(struct thp_settin } } +/* A store to either sleep knob wakes khugepaged, so write only on change */ +static void thp_update_num(const char *name, unsigned long num) +{ + if (thp_read_num(name) != num) + thp_write_num(name, num); +} + void thp_write_settings(struct thp_settings *settings) { struct khugepaged_settings *khugepaged = &settings->khugepaged; @@ -232,15 +239,15 @@ void thp_write_settings(struct thp_setti shmem_enabled_strings[settings->shmem_enabled]); thp_write_num("use_zero_page", settings->use_zero_page); - thp_write_num("khugepaged/defrag", khugepaged->defrag); - thp_write_num("khugepaged/alloc_sleep_millisecs", - khugepaged->alloc_sleep_millisecs); - thp_write_num("khugepaged/scan_sleep_millisecs", - khugepaged->scan_sleep_millisecs); - thp_write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none); - thp_write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap); - thp_write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared); - thp_write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan); + thp_update_num("khugepaged/defrag", khugepaged->defrag); + thp_update_num("khugepaged/alloc_sleep_millisecs", + khugepaged->alloc_sleep_millisecs); + thp_update_num("khugepaged/scan_sleep_millisecs", + khugepaged->scan_sleep_millisecs); + thp_update_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none); + thp_update_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap); + thp_update_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared); + thp_update_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan); if (dev_queue_read_ahead_path[0]) { int ret = write_num(dev_queue_read_ahead_path, @@ -271,6 +278,41 @@ void thp_write_settings(struct thp_setti } } +/* + * Wait for a full khugepaged scan pass that started after this call: the + * pass in progress may already have passed this mm, so full_scans has to + * advance twice. + * + * A store to scan_sleep_millisecs wakes the daemon, but one made while it + * is scanning rather than sleeping is lost, so keep storing until the pass + * lands. + * + * One wake is one pass only if pages_to_scan covers every mm on the list. + */ +bool khugepaged_full_pass(unsigned int timeout_s) +{ + unsigned long deadline_ms = timeout_s * 1000UL; + unsigned long elapsed_ms = 0, poll_ms = 10; + unsigned long sleep_ms; + int pass; + + sleep_ms = thp_read_num("khugepaged/scan_sleep_millisecs"); + for (pass = 0; pass < 2; pass++) { + unsigned long target = + thp_read_num("khugepaged/full_scans") + 1; + + while (thp_read_num("khugepaged/full_scans") < target) { + if (elapsed_ms >= deadline_ms) + return false; + thp_write_num("khugepaged/scan_sleep_millisecs", + sleep_ms); + usleep(poll_ms * 1000); + elapsed_ms += poll_ms; + } + } + return true; +} + struct thp_settings *thp_current_settings(void) { if (!settings_index) { --- a/tools/lib/mm/hugepage_settings.h~selftests-mm-add-khugepaged-completion-barrier-helper +++ a/tools/lib/mm/hugepage_settings.h @@ -83,6 +83,8 @@ static inline void thp_save_settings(voi hugepage_save_settings(/* thp = */ true, /* hugetlb = */ false); } +bool khugepaged_full_pass(unsigned int timeout_s); + void thp_set_read_ahead_path(char *path); unsigned long thp_supported_orders(void); unsigned long thp_shmem_supported_orders(void); _ 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