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 67F2B3ED13B; Tue, 21 Jul 2026 00:43:32 +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=1784594613; cv=none; b=gQqRq0Ck7vkK5coe47e9Avyi60VF+Mm7y38HbbY7wmmmeQrT+/JGZzXbICb8YsmmyLD/gBs+5yul56bvsYT3fphL7vJzdyfhF4NSlM7lFOLah6+7R0A9Q/9SN6V16J4ZjZFJyC5NgEV2t2gmpiKY6O+wyarCh3tI03jY615PN1o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784594613; c=relaxed/simple; bh=6orYouV+bU/+7lyIjQdpZkfesi82tnRAh8UUQQDdwJo=; h=Date:To:From:Subject:Message-Id; b=cmt2MXgJnk/oej1aBuUsq11X+eMaAdR8H/6iaif9gMPhRRpv7egpW0VPD8E8oiiAsOpUu5DtE9z/9YLr2KALgJoPlYIaJ8ZaYK8Fzgimsvp1BEMyq8Oz6JrzeqPj1p4dsD6YEz6ehVRnncfN35582GsSM1mtFPH+KoVnWCoB0X4= 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=QqQPOLFw; 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="QqQPOLFw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB8E01F00A3A; Tue, 21 Jul 2026 00:43:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1784594612; bh=DDPXxeMu7+XgXKblRZh2cj6Bkfbcy5Cwv1bm/0BeyM8=; h=Date:To:From:Subject; b=QqQPOLFwqzK2zbgPyk0oRsB5nzBi6acEkGCBrI4ZhCdETmMdYp+28bRCalxBJzXHo DXFz2xP46wlIfAhxhlLBKDKfNDp8pmhLG/+N1EyswxkbIF/llv/WqhUAUbA86GjkW1 uJLC0sBMs7084Bdf5DVxsNV1WlLn0WhnUuv8QiIg= Date: Mon, 20 Jul 2026 17:43:31 -0700 To: mm-commits@vger.kernel.org,vbabka@kernel.org,usama.anjum@collabora.com,surenb@google.com,stable@vger.kernel.org,shuah@kernel.org,rppt@kernel.org,pfalcato@suse.de,peterx@redhat.com,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,jannh@google.com,david@kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] fs-proc-task_mmu-fix-pagemap_scan-written-state-for-unpopulated-ptes.patch removed from -mm tree Message-Id: <20260721004331.EB8E01F00A3A@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: fs/proc/task_mmu: fix PAGEMAP_SCAN written state for unpopulated ptes has been removed from the -mm tree. Its filename was fs-proc-task_mmu-fix-pagemap_scan-written-state-for-unpopulated-ptes.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "Kiryl Shutsemau (Meta)" Subject: fs/proc/task_mmu: fix PAGEMAP_SCAN written state for unpopulated ptes Date: Tue, 7 Jul 2026 16:13:49 +0100 PAGEMAP_SCAN reports an unpopulated pte differently depending on which path serves the request. The PAGE_IS_WRITTEN fast path in pagemap_scan_pmd_entry() reports a pte_none as written (and, under PM_SCAN_WP_MATCHING, arms a marker); pagemap_page_category() returns 0 for the same pte_none. A request that cannot take the fast path (an extra category bit, category_anyof_mask or category_inverted) therefore reports the pte as clean and skips arming it. A range that was populated and then MADV_DONTNEED'd reads as written via one mask and clean via another, and in the latter case is not re-armed for the next round -- an incremental-dump consumer (e.g. CRIU) using a richer mask drops the zapped range and stops tracking writes to it. Report pte_none as written in pagemap_page_category() too. A pte_none carries no uffd-wp marker, i.e. it is not write-protected -- the same condition under which the present and swap cases already report PAGE_IS_WRITTEN. The fast path applies no VMA test, so neither does this. The hugetlb and fully-unpopulated-PMD (no page table) scans have no PAGE_IS_WRITTEN fast path, so they do not exhibit the per-entry divergence and are left unchanged. Add a pagemap_ioctl selftest that populates a range, drops it with MADV_DONTNEED, and checks that the fast path and the generic (category_anyof_mask) path both report every page written. Link: https://lore.kernel.org/20260707151349.92143-1-kirill@shutemov.name Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag") Signed-off-by: Kiryl Shutsemau Cc: Muhammad Usama Anjum Cc: David Hildenbrand Cc: Jann Horn Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Pedro Falcato Cc: Peter Xu Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Assisted-by: Claude:claude-fable-5 Cc: Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 14 ++++ tools/testing/selftests/mm/pagemap_ioctl.c | 56 ++++++++++++++++++- 2 files changed, 67 insertions(+), 3 deletions(-) --- a/fs/proc/task_mmu.c~fs-proc-task_mmu-fix-pagemap_scan-written-state-for-unpopulated-ptes +++ a/fs/proc/task_mmu.c @@ -2432,8 +2432,18 @@ static unsigned long pagemap_page_catego { unsigned long categories; - if (pte_none(pte)) - return 0; + if (pte_none(pte)) { + /* + * An unpopulated pte carries no uffd-wp marker, i.e. it is not + * write-protected, the same condition under which the present + * and swap cases below report PAGE_IS_WRITTEN. Report it here + * too so this generic path agrees with the PAGE_IS_WRITTEN fast + * path in pagemap_scan_pmd_entry(), which reports pte_none as + * written and, under PM_SCAN_WP_MATCHING, arms a marker. The + * fast path applies no VMA test, so neither does this. + */ + return PAGE_IS_WRITTEN; + } if (pte_present(pte)) { struct page *page; --- a/tools/testing/selftests/mm/pagemap_ioctl.c~fs-proc-task_mmu-fix-pagemap_scan-written-state-for-unpopulated-ptes +++ a/tools/testing/selftests/mm/pagemap_ioctl.c @@ -1051,6 +1051,57 @@ static void test_simple(void) ksft_test_result(i == TEST_ITERATIONS, "Test %s\n", __func__); } +/* + * A range that was populated and then MADV_DONTNEED'd is genuine pte_none + * with no uffd-wp marker. Such a pte must read the same regardless of which + * PAGEMAP_SCAN path serves the request: both the PAGE_IS_WRITTEN fast path and + * the generic path (reached e.g. via category_anyof_mask) must report every + * page written. + */ +static void unpopulated_scan_test(void) +{ + int npages = 16, i; + long mem_size = npages * page_size; + struct page_region regions[16]; + long fast = 0, slow = 0, ret; + char *mem; + + mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (mem == MAP_FAILED) + ksft_exit_fail_msg("%s mmap failed\n", __func__); + + wp_init(mem, mem_size); + + /* Populate, then drop: the ptes become pte_none without a marker. */ + memset(mem, 1, mem_size); + if (madvise(mem, mem_size, MADV_DONTNEED)) + ksft_exit_fail_msg("%s MADV_DONTNEED failed\n", __func__); + + /* Fast path: category_mask == return_mask == PAGE_IS_WRITTEN. */ + ret = pagemap_ioctl(mem, mem_size, regions, npages, 0, 0, + PAGE_IS_WRITTEN, 0, 0, PAGE_IS_WRITTEN); + if (ret < 0) + ksft_exit_fail_msg("%s fast scan failed\n", __func__); + for (i = 0; i < ret; i++) + fast += LEN(regions[i]); + + /* Generic path: same query expressed via category_anyof_mask. */ + ret = pagemap_ioctl(mem, mem_size, regions, npages, 0, 0, + 0, PAGE_IS_WRITTEN, 0, PAGE_IS_WRITTEN); + if (ret < 0) + ksft_exit_fail_msg("%s generic scan failed\n", __func__); + for (i = 0; i < ret; i++) + slow += LEN(regions[i]); + + ksft_test_result(fast == npages && slow == npages, + "%s unpopulated ptes reported written by both paths (%ld, %ld of %d)\n", + __func__, fast, slow, npages); + + wp_free(mem, mem_size); + munmap(mem, mem_size); +} + int sanity_tests(void) { unsigned long long mem_size, vec_size; @@ -1559,7 +1610,7 @@ int main(int __attribute__((unused)) arg if (!hugetlb_setup_default(4)) ksft_print_msg("HugeTLB test will be skipped\n"); - ksft_set_plan(117); + ksft_set_plan(118); page_size = getpagesize(); hpage_size = read_pmd_pagesize(); @@ -1737,6 +1788,9 @@ int main(int __attribute__((unused)) arg /* 17. ZEROPFN tests */ zeropfn_tests(); + /* 18. Unpopulated pte scan-path consistency */ + unpopulated_scan_test(); + close(pagemap_fd); ksft_finished(); } _ Patches currently in -mm which might be from kas@kernel.org are mm-huge_memory-unlock-i_mmap_rwsem-before-releasing-after-split-folios.patch mm-decouple-protnone-helpers-from-config_numa_balancing.patch mm-rename-uffd-wp-pte-bit-macros-to-uffd.patch mm-rename-uffd-wp-pte-accessors-to-uffd.patch userfaultfd-test-uffd-vma-flags-through-the-vma_flags_t-api.patch mm-add-vm_uffd_rwp-vma-flag.patch mm-add-mm_cp_uffd_rwp-change_protection-flag.patch mm-preserve-rwp-marker-across-pte-rewrites.patch mm-handle-vm_uffd_rwp-in-khugepaged-rmap-and-gup.patch userfaultfd-add-uffdio_register_mode_rwp-and-uffdio_rwprotect-plumbing.patch mm-userfaultfd-add-rwp-fault-delivery-and-expose-uffdio_register_mode_rwp.patch mm-pagemap-add-page_is_accessed-for-rwp-tracking.patch userfaultfd-add-uffd_feature_rwp_async-for-async-fault-resolution.patch userfaultfd-add-uffdio_set_mode-for-runtime-sync-async-toggle.patch selftests-mm-add-userfaultfd-rwp-tests.patch documentation-userfaultfd-document-rwp-working-set-tracking.patch selftests-mm-add-pagemap_scan-test-for-thp-pmd-holes.patch mm-huge_memory-remove-unused-can_split_folio.patch mm-huge_memory-fold-split_folio_to_list_to_order-into-split_folio_to_order.patch