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 D68D74848A6 for ; Tue, 13 Oct 2026 04:33:57 +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=1791866039; cv=none; b=IO9eduaeAUGM0IAwzJHv1IiJEHG1l5QOuOeGv26mM8yr67OR/3omz0WRDZkKhg5WGo1o+PHTslsn2g5/67oT32X25BWBPja2/ZugxysK2Z9Pcjdx+y2uaRwi/5BZFdmBk6CWD4Y7mAX29dQY8F+XntJAgKqeS+pJ6RaFCxh7dFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791866039; c=relaxed/simple; bh=l7Sfh42QildSPHgS5ojUHcS+Z6b2iSAOwCsOH9jifmg=; h=Date:To:From:Subject:Message-Id; b=bJywGj+5Xr//XV7qDUTwXlafbU+dgjuTr/5bMgaufNfhximIqMZMKCPlzndvQ1bbBjAGgbryJDmcInfnoIzCqQ5Tfp2+ftLYao7bWLFa3RLToRkJ+OAJrIT7Dl3dhOtwh5Vk8ukg3cOg2PYXOUL/F7e0+1Rtt7TVS7G5NBidBmw= 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=ebIof5m0; 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="ebIof5m0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC31B1F000FF; Tue, 13 Oct 2026 04:33:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791866037; bh=1nNbVrMoElAC1JdiXjE+9tigTCS0Vnw4zod8SL686iM=; h=Date:To:From:Subject; b=ebIof5m0u/aOaJn35CWSbpFj05wMi1tGsr9LRDSsu9fdxlFSCQzRWirV+awIJgAXF nHKzrp5UDVE9uuD/pIJvUABqzozFaTp6TYltsyfz69LjBLX6TMj6j9v1gy7PZryP02 ObJ/w64MP04S2gHmPpf4yiZBk/LqZtzWk50rIRIU= Date: Mon, 12 Oct 2026 21:33:57 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,usama.arif@linux.dev,usama.anjum@arm.com,surenb@google.com,shuah@kernel.org,ryan.roberts@arm.com,rppt@kernel.org,nico.pache@linux.dev,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,leon@kernel.org,lance.yang@linux.dev,kernel-team@meta.com,jgg@ziepe.ca,hughd@google.com,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,agordeev@linux.ibm.com,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] selftests-mm-race-the-collapse-of-windows-with-holes.patch removed from -mm tree Message-Id: <20261013043357.AC31B1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: selftests/mm: race the collapse of windows with holes has been removed from the -mm tree. Its filename was selftests-mm-race-the-collapse-of-windows-with-holes.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "Kiryl Shutsemau (Meta)" Subject: selftests/mm: race the collapse of windows with holes Date: Sat, 19 Sep 2026 01:24:47 +0100 The harness pins max_ptes_none to 0, so khugepaged only collapses a window once every PTE in it is present. A window with holes takes a different route, and never gets raced. A hole is zero-filled in the new folio rather than copied. Which slots count as holes keeps moving under the racing MADV_DONTNEED, right up to the moment the PMD is detached. Run both ends of the occupancy scale for every driver mode, one after the other. mTHP collapse supports only those two, 0 and HPAGE_PMD_NR - 1, and coerces anything between them to 0. Each result says which end it ran: ok 1 stepped/strict: 5s, 231 steps, no corruption ok 2 stepped/holes: 5s, 194 steps, no corruption Link: https://lore.kernel.org/20260919002451.496763-18-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau (Meta) Signed-off-by: Andrew Morton Tested-by: Muhammad Usama Anjum Assisted-by: LLM Cc: Alexander Gordeev Cc: Baolin Wang 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: Lorenzo Stoakes (ARM) Cc: Michal Hocko Cc: Mike Rapoport (Microsoft) 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_race.c | 32 ++++++++++------- 1 file changed, 20 insertions(+), 12 deletions(-) --- a/tools/testing/selftests/mm/khugepaged_race.c~selftests-mm-race-the-collapse-of-windows-with-holes +++ a/tools/testing/selftests/mm/khugepaged_race.c @@ -236,6 +236,8 @@ int main(int argc, char **argv) const int nr_threads = ARRAY_SIZE(thread_names); pthread_t threads[ARRAY_SIZE(thread_names)]; static const char * const all_modes[] = { "stepped", "free", "madvise" }; + static const bool occupancies[] = { false, true }; /* strict, holes */ + const int nr_occupancies = ARRAY_SIZE(occupancies); const char *one_mode[1]; const char * const *modes = all_modes; int nr_modes = ARRAY_SIZE(all_modes); @@ -303,7 +305,7 @@ int main(int argc, char **argv) -1, 0) != (void *)mremap_scratch) ksft_exit_fail_perror("mmap() mremap scratch"); - ksft_set_plan(nr_modes); + ksft_set_plan(nr_modes * nr_occupancies); thp_save_settings(); thp_read_settings(&settings); @@ -311,8 +313,9 @@ int main(int argc, char **argv) /* Base of the settings stack; the bottom entry is never popped */ thp_push_settings(&settings); - for (int m = 0; m < nr_modes; m++) { - const char *mode = modes[m]; + for (int run = 0; run < nr_modes * nr_occupancies; run++) { + const char *mode = modes[run / nr_occupancies]; + bool holes = occupancies[run % nr_occupancies]; thp_read_settings(&settings); settings.thp_enabled = THP_MADVISE; @@ -322,12 +325,14 @@ int main(int argc, char **argv) settings.khugepaged.scan_sleep_millisecs = strcmp(mode, "free") ? 1000 : 0; settings.khugepaged.alloc_sleep_millisecs = 10; + /* - * mTHP collapse honours only 0 or HPAGE_PMD_NR - 1 here, and 0 - * keeps a step from being spent on PMD allocations that racing - * MADV_DONTNEED will not let succeed. + * mTHP collapse honours only 0 or HPAGE_PMD_NR - 1 here. The two + * ends race different paths: a strict window has every PTE + * present, a hole-heavy one is mostly zero-filled. */ - settings.khugepaged.max_ptes_none = 0; + settings.khugepaged.max_ptes_none = holes ? + (hpage_pmd_size / page_size) - 1 : 0; /* One wake, one pass: the playground plus the forked children's copies */ settings.khugepaged.pages_to_scan = nr_areas * (hpage_pmd_size / page_size) * 8; @@ -393,8 +398,9 @@ int main(int argc, char **argv) check_page(i); ksft_test_result(!corrupted, - "%s: %ds, %d steps, no corruption\n", - mode, duration_s, steps); + "%s/%s: %ds, %d steps, no corruption\n", + mode, holes ? "holes" : "strict", + duration_s, steps); /* The next mode maps the same fixed address with its own settings */ munmap(region, nr_areas * hpage_pmd_size); @@ -404,9 +410,11 @@ int main(int argc, char **argv) if (corrupted) { /* Memory is suspect; the rest would prove nothing */ - while (++m < nr_modes) - ksft_test_result_skip("%s: skipped after corruption\n", - modes[m]); + while (++run < nr_modes * nr_occupancies) + ksft_test_result_skip("%s/%s: skipped after corruption\n", + modes[run / nr_occupancies], + occupancies[run % nr_occupancies] ? + "holes" : "strict"); break; } } _ Patches currently in -mm which might be from kas@kernel.org are mm-page_alloc-make-defrag_mode-retries-follow-the-promoted-order.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-call-collapse_file-from-collapse_single_pmd.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