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Perez de Azpillaga" Cc: Andrew Morton , David Hildenbrand , Shuah Khan , Peter Xu , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Muchun Song , Oscar Salvador Subject: Re: [PATCH v2 2/2] selftests/mm: add a uffd test for re-registering during UFFDIO_COPY Message-ID: References: <20261102081140.201987-1-azpijr@gmail.com> <20261102081140.201987-3-azpijr@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261102081140.201987-3-azpijr@gmail.com> X-Rspamd-Queue-Id: D62DF10000C X-Stat-Signature: fsc7ez7tqe1w6mim4fh3j3zyu6xdqwjs X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793614081-77625 X-HE-Meta: U2FsdGVkX1/roab0qVWRmgIQ3NWcWuAjirEb9AGQZ9K/qJhyShcuGgpC9J3se+R3WZSF6Hm6KQXw7RjRMs/n35orAs0vAx8r/sMLbIUpNwbgaXRejPOKagN51YqKRngmXKcD6L+JihKyh4QplilLi4tmE+7S1xJ4RIE9gMeti9YkpdckI7wi5T2dKX1okhCqZwbczOtD7CbZ1XYHm18BqlyMjw6ySEjWr9ZwAuLNOIzjFlvKjJL9WEW68WdEDj/38Y/14jWSej5atpeKVzIFhYSane1T3lsy5Ly6uf8Ukde7tBJ820aOhDzUm2G637334XDSG2NK3wz5iLTNjnWIuhQnbSvXlqaB6mYjo5AV883ds22eeCVx892uaHy0CiKDjkmbsNbnck0pTBwU2MR2tg8HGy1yh22kxN/uZXxJL4cvAuWlfR6X4mTFEk3pEGLMsTAM4y4MG1NjObWcXEfsFG/xCR+Px9K+kbJ90ORP5x5SOY74E5uRv8Jw89o0IprkCBsydcImU5IkIaOWIYFajPNc4bYROlUwODX1S+ADb6nmv73Ca4NbgliyebsPwpnIXXQk1MOIeBbwU3BeJTMkaGhTSwqeZXxNY7uT+zGYUVWv5ShLprI01Mc94rfpXBQmI2+Gba2d+N1pj4d4y8t8vZz6iY7AuudcjghwqUgwCBJOtSj/raZQXALhwk2R+2pqBQKmVdOINSc9gfilNh2ZZbwU6IgoUxmIH0WJBKJj8BTp+0GGgg/eXXzoMq+2d7sVOJjhmK+koQ3Uw5pju9gNmBs2BMYSv1fhNITmSCFEGu94a+vEguAMWmdHv3K7AXJOgfccmdrbecrK40Eiq2mZjuYLQKH2FAPgdFk93XX9rFcAYHXBZjLlwgbXUg+VyjQOW8b8KFRTXWq8KqBTIdN52XyaxxhRf5xPz/FGeudDFQ/DPk7s2lvtmHqNWTi+Rq4G2JQZrSkj73EpruuN5qj C1Z0Xuv7 IbRtKymIA/0pEqUSpWZRG35rjCPOGnC8uFMXqAE9fpqQPicHANqibYGg8P6tPcANwzX3N51DIg7grQchfz5u6imLq2Hy3kjJu5ff8dXHKqnc/0aCnqT3BxJbEDNllC9Jl6GhsoaKkGy9QqSNbImmbkVB/Tl8PrLbxZBK1+lXymZqvEm2r+4gTBQAZJdbP3WZieEqtpbc0kRBIcQqeoxNREOJVIo4Y17FKQY7A+4VlpCcocMKLyuti+I4dWlz0aMJkJCvxYZNeIKbLfUcWwTyM8tfavHhLz9PtxjnLcBrZ0GVbfkdCiuQX0UN83fy7wk96pyCQ2Zr09LW7Ltje1V6JK+uI+HbbGiJOqsnI Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon, Nov 02, 2026 at 09:11:31AM +0100, Jose A. Perez de Azpillaga wrote: > Re-register the destination without WP while a UFFDIO_COPY_MODE_WP copy > waits for its source page, then check that the copy fails with -EINVAL > and leaves no uffd-wp bit behind. This covers all memory types. > > Signed-off-by: Jose A. Perez de Azpillaga Reviewed-by: Mike Rapoport (Microsoft) > --- > Changes in v2: > - "all memory types" in the commit message > - rename copy to result > > v1: https://lore.kernel.org/20261029221129.89068-3-azpijr@gmail.com > > tools/testing/selftests/mm/uffd-unit-tests.c | 105 +++++++++++++++++++ > 1 file changed, 105 insertions(+) > > diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c > index 2a97ba1d6feb..cc22b4cde621 100644 > --- a/tools/testing/selftests/mm/uffd-unit-tests.c > +++ b/tools/testing/selftests/mm/uffd-unit-tests.c > @@ -375,6 +375,104 @@ static void uffd_wp_unpopulated_test(uffd_global_test_opts_t *gopts, uffd_test_a > uffd_test_pass(); > } > > +struct wp_copy_args { > + uffd_global_test_opts_t *gopts; > + char *src; > + __s64 result; > +}; > + > +static void *wp_copy_thread(void *data) > +{ > + struct wp_copy_args *args = data; > + struct uffdio_copy copy = { > + .dst = (unsigned long)args->gopts->area_dst, > + .src = (unsigned long)args->src, > + .len = args->gopts->page_size, > + .mode = UFFDIO_COPY_MODE_WP, > + }; > + > + ioctl(args->gopts->uffd, UFFDIO_COPY, ©); > + args->result = copy.copy; > + > + return NULL; > +} > + > +/* > + * UFFDIO_COPY drops its locks to fault in the source page. Re-register the > + * destination without WP while it waits there: the MODE_WP copy must then > + * fail instead of leaving a uffd-wp bit in a VMA that no longer has WP. > + */ > +static void uffd_wp_copy_reregister_test(uffd_global_test_opts_t *gopts, > + uffd_test_args_t *args) > +{ > + struct uffdio_api api = { .api = UFFD_API }; > + struct wp_copy_args copy_args = { .gopts = gopts }; > + unsigned long len = gopts->page_size; > + struct uffdio_zeropage zeropage; > + struct uffd_msg msg; > + struct pollfd pfd; > + pthread_t thread; > + uint64_t value; > + int pagemap_fd; > + int src_uffd; > + > + /* The source fault comes from the kernel, so no UFFD_USER_MODE_ONLY */ > + src_uffd = uffd_open(O_CLOEXEC); > + if (src_uffd < 0) { > + uffd_test_skip("cannot open a kernel-mode userfaultfd"); > + return; > + } > + if (ioctl(src_uffd, UFFDIO_API, &api)) > + err("UFFDIO_API failed"); > + > + copy_args.src = mmap(NULL, len, PROT_READ | PROT_WRITE, > + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > + if (copy_args.src == MAP_FAILED) > + err("mmap() failed"); > + > + if (uffd_register(src_uffd, copy_args.src, len, true, false, false)) > + err("register src failed"); > + if (uffd_register(gopts->uffd, gopts->area_dst, len, true, true, false)) > + err("register dst failed"); > + > + if (pthread_create(&thread, NULL, wp_copy_thread, ©_args)) > + err("pthread_create() failed"); > + > + /* Wait until UFFDIO_COPY blocks on the source page */ > + pfd = (struct pollfd){ .fd = src_uffd, .events = POLLIN }; > + if (poll(&pfd, 1, 10000) != 1) > + err("no fault on the source page"); > + if (read(src_uffd, &msg, sizeof(msg)) != sizeof(msg)) > + err("read() failed"); > + > + if (uffd_unregister(gopts->uffd, gopts->area_dst, len)) > + err("unregister dst failed"); > + if (uffd_register(gopts->uffd, gopts->area_dst, len, true, false, false)) > + err("re-register dst failed"); > + > + zeropage.range.start = (unsigned long)copy_args.src; > + zeropage.range.len = len; > + zeropage.mode = 0; > + if (ioctl(src_uffd, UFFDIO_ZEROPAGE, &zeropage)) > + err("UFFDIO_ZEROPAGE failed"); > + > + if (pthread_join(thread, NULL)) > + err("pthread_join() failed"); > + > + if (copy_args.result != -EINVAL) > + err("UFFDIO_COPY returned %lld, expected %d", > + (long long)copy_args.result, -EINVAL); > + > + pagemap_fd = pagemap_open(); > + value = pagemap_get_entry(pagemap_fd, gopts->area_dst); > + pagemap_check_wp(value, false); > + close(pagemap_fd); > + > + munmap(copy_args.src, len); > + close(src_uffd); > + uffd_test_pass(); > +} > + > static void uffd_wp_fork_test_common(uffd_global_test_opts_t *gopts, uffd_test_args_t *args, > bool with_event) > { > @@ -2403,6 +2501,13 @@ uffd_test_case_t uffd_tests[] = { > .uffd_feature_required = > UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_UNPOPULATED, > }, > + { > + .name = "wp-copy-reregister", > + .uffd_fn = uffd_wp_copy_reregister_test, > + .mem_targets = MEM_ALL, > + .uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP | > + UFFD_FEATURE_WP_HUGETLBFS_SHMEM, > + }, > { > .name = "minor", > .uffd_fn = uffd_minor_test, > -- > 2.56.0 > -- Sincerely yours, Mike.