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Sat, 03 Oct 2026 03:30:42 -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, kas@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, donggeunyoo.kernel@gmail.com Subject: [PATCH v4 2/2] selftests/mm: add tests for UFFDIO_MOVE of a uffd-protected swap entry Date: Sat, 3 Oct 2026 19:30:30 +0900 Message-ID: <20261003103030.63380-3-donggeunyoo.kernel@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261003103030.63380-1-donggeunyoo.kernel@gmail.com> References: <20261003103030.63380-1-donggeunyoo.kernel@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Move a swapped-out page out of a write-protected or RWP-protected area into a destination registered for missing faults only, and read pagemap bit 57 at the destination. The destination was never protected, so the bit must be clear. Assisted-by: LLM Signed-off-by: Donggeun Yoo --- tools/testing/selftests/mm/uffd-unit-tests.c | 84 ++++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index ef9b3956bdcfd..97484c82f24e1 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -2037,6 +2037,75 @@ static void uffd_move_pmd_split_test(uffd_global_test_opts_t *gopts, uffd_test_a uffd_move_pmd_handle_fault); } +/* + * Moving a swapped-out page out of a write-protected or RWP-protected area + * must not carry the uffd bit into a destination registered for missing + * faults only: such a bit is never cleared afterwards, so pagemap keeps + * reporting the page as uffd-tracked. + * + * Needs a swap device; skipped if MADV_PAGEOUT cannot evict the page. + */ +static void uffd_move_swap_test_common(uffd_global_test_opts_t *gopts, + bool rwp) +{ + unsigned long page_size = gopts->page_size; + struct uffdio_move move = { + .dst = (unsigned long)gopts->area_dst, + .src = (unsigned long)gopts->area_src, + .len = page_size, + }; + int pagemap_fd = pagemap_open(); + + if (rwp) { + if (uffd_register_rwp(gopts->uffd, gopts->area_src, page_size)) + err("register src failure"); + rwprotect_range(gopts->uffd, (unsigned long)gopts->area_src, + page_size, true); + } else { + if (uffd_register(gopts->uffd, gopts->area_src, page_size, + false, true, false)) + err("register src failure"); + wp_range(gopts->uffd, (unsigned long)gopts->area_src, + page_size, true); + } + if (uffd_register(gopts->uffd, gopts->area_dst, page_size, + true, false, false)) + err("register dst failure"); + + if (madvise(gopts->area_src, page_size, MADV_PAGEOUT)) + err("MADV_PAGEOUT"); + if (!pagemap_is_swapped(pagemap_fd, gopts->area_src)) { + uffd_test_skip("MADV_PAGEOUT did not swap the page; is swap enabled?"); + goto out; + } + + if (ioctl(gopts->uffd, UFFDIO_MOVE, &move)) { + uffd_test_fail("UFFDIO_MOVE failed: %s", strerror(errno)); + goto out; + } + + if (pagemap_get_entry(pagemap_fd, gopts->area_dst) & PM_UFFD_WP) + uffd_test_fail("uffd bit moved into an area registered for missing faults only"); + else + uffd_test_pass(); +out: + close(pagemap_fd); + uffd_unregister(gopts->uffd, gopts->area_src, page_size); + uffd_unregister(gopts->uffd, gopts->area_dst, page_size); +} + +static void uffd_move_swap_wp_test(uffd_global_test_opts_t *gopts, + uffd_test_args_t *targs) +{ + uffd_move_swap_test_common(gopts, false); +} + +static void uffd_move_swap_rwp_test(uffd_global_test_opts_t *gopts, + uffd_test_args_t *targs) +{ + uffd_move_swap_test_common(gopts, true); +} + static bool uffdio_verify_results(const char *name, int ret, int error, long result) { @@ -2359,6 +2428,21 @@ uffd_test_case_t uffd_tests[] = { .uffd_feature_required = UFFD_FEATURE_MOVE, .test_case_ops = &uffd_move_test_pmd_case_ops, }, + { + .name = "move-swap-wp", + .uffd_fn = uffd_move_swap_wp_test, + .mem_targets = MEM_ANON, + .uffd_feature_required = UFFD_FEATURE_MOVE | + UFFD_FEATURE_PAGEFAULT_FLAG_WP, + .test_case_ops = &uffd_move_test_case_ops, + }, + { + .name = "move-swap-rwp", + .uffd_fn = uffd_move_swap_rwp_test, + .mem_targets = MEM_ANON, + .uffd_feature_required = UFFD_FEATURE_MOVE | UFFD_FEATURE_RWP, + .test_case_ops = &uffd_move_test_case_ops, + }, { .name = "wp-fork", .uffd_fn = uffd_wp_fork_test, -- 2.53.0