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Sat, 26 Sep 2026 05:41:51 -0700 (PDT) From: Donggeun Yoo To: akpm@linux-foundation.org, rppt@kernel.org Cc: peterx@redhat.com, surenb@google.com, aarcange@redhat.com, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, mhocko@suse.com, shuah@kernel.org, kirill@shutemov.name, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, donggeunyoo.kernel@gmail.com Subject: [PATCH v3 0/2] userfaultfd: clear the inherited uffd bit in move_swap_pte() Date: Sat, 26 Sep 2026 21:41:43 +0900 Message-ID: <20260926124145.2878520-1-donggeunyoo.kernel@gmail.com> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Stat-Signature: k3a19scncsf517ewf1yzt1yepyyiwezh X-Rspam-User: X-Rspamd-Queue-Id: 5832F40005 X-HE-Tag: 1790426513-890591 X-HE-Meta: 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 MCTyBkw9 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: UFFDIO_MOVE on a swapped-out page installs the source PTE at the destination unchanged, so a uffd bit set on a write-protected or RWP-protected source lands in a destination VMA that was never registered for either, and nothing clears it afterwards. Patch 1 clears the bit, then re-arms it if the destination is RWP-registered, which is what the present-page and zeropage move paths already do. Patch 2 adds the tests that catch it. v1: https://lore.kernel.org/all/20260919004630.1159895-1-donggeunyoo.kernel@gmail.com/ v2: https://lore.kernel.org/all/20260925042907.2330519-1-donggeunyoo.kernel@gmail.com/ Changes in v3: - patch 1: describe the userspace-visible effects and the backport (Andrew Morton, David Hildenbrand) - patch 2: drop the MADV_PAGEOUT retry loop (David Hildenbrand) - patch 2: add an RWP case (David Hildenbrand) Changes in v2: - patch 1: clear the bit unconditionally (Kiryl Shutsemau) - patch 1: rewrite the changelog for readability (Mike Rapoport) - add Assisted-by: LLM (Mike Rapoport) x86_64 defconfig plus USERFAULTFD, TRANSPARENT_HUGEPAGE, PAGE_TABLE_CHECK_ENFORCED and a swap device, under QEMU, on 6812ce4e4379: uffd-unit-tests before after move-swap-wp on anon not ok ok move-swap-rwp on anon not ok ok the other 103 unit tests ok ok uffd-wp-mremap, 38 tests ok ok 11 unit tests skip on both, as CONFIG_GUP_TEST is not set. pagemap bit 57 at the destination before after swapped page, dst not armed set clear swapped page, dst WP-armed set clear swapped page, dst RWP-armed set set resident page, dst WP-armed clear clear MADV_COLLAPSE over 2 MB at dst EINVAL 0 fault on the moved page at dst WARNING none Donggeun Yoo (2): userfaultfd: clear the inherited uffd bit in move_swap_pte() selftests/mm: add tests for UFFDIO_MOVE of a uffd-protected swap entry mm/userfaultfd.c | 1 + tools/testing/selftests/mm/uffd-unit-tests.c | 84 ++++++++++++++++++++ 2 files changed, 85 insertions(+) -- 2.53.0