From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 014F11B7F4; Thu, 19 Mar 2026 19:34:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773948873; cv=none; b=dTtsrkIxTNNlK4yr1aGJxSY7tRwnbQWxsmDB7nTV0462wzjy/QUe2cEESuDRi1lXIEmG+RIEWu+Zkl5nYH030LXY/jmq23wsLrc0jRdHs9cOLwfG+nOhwG9VvVUWJTBP1pecwUnS+JkH8uj5jXZFYvCN4TyhS7mYsvLl3y7NjJI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773948873; c=relaxed/simple; bh=ttQMTVuPbzMAIJ3FjJEZOWfVsx+LSE1iB5b8DNBMCfI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F3cGGk2V0QjJmqT47n/hLmfuKqKD/F0cJZr8ZFj9kSZ/bkcx4RuDwTNtAD2VvP0a3yHD1DAxNxqrzi2kyc5ciK+bXJo9Y9vJiBKSgrq2u1OVdev7SceLSgWWa4j/4KoDp7CEZEdwJYvBgZ7m6gJXBiBO/dQHBMN8Spts24YTzjU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JJEEV6W5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JJEEV6W5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E8C1C19424; Thu, 19 Mar 2026 19:34:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773948872; bh=ttQMTVuPbzMAIJ3FjJEZOWfVsx+LSE1iB5b8DNBMCfI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JJEEV6W52iY/HDjBfXoTrlMDBS0r+joQZ42qcpW8R5c23OsI4ibiflq5qVHZJcymM 67yvKoyPcwuFMVi8ET7jw7ldvzjqggp6taWtEBA6vR7cWwOuSgpM613fYay3xDHaLy SZ1wamtIw9gDmeiZL0tWuWCgUbh644YTe+rwak3Zd2Iezl06mgL8cmwupFesaLqUPs xE7kpzk0tfE3hfQzMwVHsIbkQct4cSIE/r5rN9GXbEr3hUJ+6zqFcE0RD8LxLPVPlF KHg1DBEvxopjzr/P8JrIhDSdius6IH751fhT8ahR0mefmv7Vtob9zns9pxH8Kft1TM YQrMVCQBBMofg== Message-ID: Date: Thu, 19 Mar 2026 20:34:27 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] selftests/mm: Add UFFDIO_MOVE huge zeropage PMD regression test To: Chris Down , Andrew Morton Cc: Mike Rapoport , Peter Xu , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Matthew Wilcox , kernel-team@fb.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/18/26 05:18, Chris Down wrote: > The existing uffd-unit-tests move-pmd coverage exercises PMD-sized > UFFDIO_MOVE on anonymous THPs, but it does not force the huge zeropage > PMD path in move_pages_huge_pmd(). > > Add a dedicated anonymous UFFDIO_MOVE PMD test that exercises this > relatively comprehensively. > > Signed-off-by: Chris Down > --- > tools/testing/selftests/mm/uffd-unit-tests.c | 100 +++++++++++++++++++ > tools/testing/selftests/mm/vm_util.c | 12 +++ > tools/testing/selftests/mm/vm_util.h | 1 + > 3 files changed, 113 insertions(+) > > diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c > index 6f5e404a446c..9cc4cbab9a23 100644 > --- a/tools/testing/selftests/mm/uffd-unit-tests.c > +++ b/tools/testing/selftests/mm/uffd-unit-tests.c > @@ -1227,6 +1227,99 @@ static void uffd_move_pmd_test(uffd_global_test_opts_t *gopts, uffd_test_args_t > uffd_move_pmd_handle_fault); > } > > +static void uffd_move_pmd_huge_zeropage_test(uffd_global_test_opts_t *gopts, > + uffd_test_args_t *targs) > +{ > + unsigned long pmd_size = read_pmd_pagesize(); > + unsigned long pmd_pages; > + unsigned long bytes = gopts->nr_pages * gopts->page_size; > + char *orig_area_src = gopts->area_src, *orig_area_dst = gopts->area_dst; > + char *aligned_src, *aligned_dst; > + unsigned long src_offs, dst_offs, max_offs; > + pthread_t uffd_mon; > + struct uffd_args args = { 0 }; > + char c = '\0'; > + int pagemap_fd; > + > + if (pmd_size <= gopts->page_size) { > + uffd_test_skip("huge page size is 0, feature missing?"); Wouldn't a check for 0 be "!pmd_size" ? :) But yes, this is unexpected. Maybe simply "Could not detect PMD size" > + return; > + } > + if (!detect_huge_zeropage()) { > + uffd_test_skip("transparent huge zeropage disabled"); > + return; > + } > + > + pmd_pages = pmd_size / gopts->page_size; Might consider s/pmd_pages/nr_pages_per_pmd/ [...] > > +bool pagemap_is_huge_zero(int fd, char *start) > +{ > + uint64_t categories; > + > + if (!pagemap_scan_supported(fd, start)) > + return false; > + > + categories = pagemap_scan_get_categories(fd, start); A slightly nicer way to write it might be const uint64_t expected = PAGE_IS_PRESENT | PAGE_IS_PFNZERO | PAGE_IS_HUGE; ... return (categories & expected) == huge_zero; In general, lgtm, thanks! -- Cheers, David