From nobody Fri Sep 12 13:38:18 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BCEBC7EE2E for ; Tue, 13 Jun 2023 03:12:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239594AbjFMDMC (ORCPT ); Mon, 12 Jun 2023 23:12:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240450AbjFMDLL (ORCPT ); Mon, 12 Jun 2023 23:11:11 -0400 Received: from ubuntu20 (unknown [193.203.214.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51E47172A for ; Mon, 12 Jun 2023 20:09:50 -0700 (PDT) Received: by ubuntu20 (Postfix, from userid 1003) id D996AE22D8; Tue, 13 Jun 2023 11:09:48 +0800 (CST) From: Yang Yang To: akpm@linux-foundation.org, david@redhat.com Cc: yang.yang29@zte.com.cn, imbrenda@linux.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn, xu.xin.sc@gmail.com, xu.xin16@zte.com.cn, Xuexin Jiang Subject: [PATCH RESEND v10 5/5] selftest: add a testcase of ksm zero pages Date: Tue, 13 Jun 2023 11:09:47 +0800 Message-Id: <20230613030947.186089-1-yang.yang29@zte.com.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <202306131104554703428@zte.com.cn> References: <202306131104554703428@zte.com.cn> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: xu xin Add a function test_unmerge_zero_page() to test the functionality on unsharing and counting ksm-placed zero pages and counting of this patch series. test_unmerge_zero_page() actually contains four subjct test objects: (1) whether the count of ksm zero pages can update correctly after merging; (2) whether the count of ksm zero pages can update correctly after unmerging by madvise(...MADV_UNMERGEABLE); (3) whether the count of ksm zero pages can update correctly after unmerging by triggering write fault. (4) whether ksm zero pages are really unmerged. Signed-off-by: xu xin Acked-by: David Hildenbrand Reviewed-by: Xiaokai Ran Reviewed-by: Yang Yang Cc: Claudio Imbrenda Cc: Xuexin Jiang --- tools/testing/selftests/mm/ksm_functional_tests.c | 98 +++++++++++++++++++= +++- 1 file changed, 97 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/test= ing/selftests/mm/ksm_functional_tests.c index 26853badae70..0de9d33cd565 100644 --- a/tools/testing/selftests/mm/ksm_functional_tests.c +++ b/tools/testing/selftests/mm/ksm_functional_tests.c @@ -29,6 +29,8 @@ =20 static int ksm_fd; static int ksm_full_scans_fd; +static int proc_self_ksm_stat_fd; +static int ksm_use_zero_pages_fd; static int pagemap_fd; static size_t pagesize; =20 @@ -59,6 +61,33 @@ static bool range_maps_duplicates(char *addr, unsigned l= ong size) return false; } =20 +static long get_my_ksm_zero_pages(void) +{ + char buf[200]; + char *substr_ksm_zero; + size_t value_pos; + ssize_t read_size; + unsigned long my_ksm_zero_pages; + + if (!proc_self_ksm_stat_fd) + return 0; + + read_size =3D pread(proc_self_ksm_stat_fd, buf, sizeof(buf) - 1, 0); + if (read_size < 0) + return -errno; + + buf[read_size] =3D 0; + + substr_ksm_zero =3D strstr(buf, "ksm_zero_pages"); + if (!substr_ksm_zero) + return 0; + + value_pos =3D strcspn(substr_ksm_zero, "0123456789"); + my_ksm_zero_pages =3D strtol(substr_ksm_zero + value_pos, NULL, 10); + + return my_ksm_zero_pages; +} + static long ksm_get_full_scans(void) { char buf[10]; @@ -159,6 +188,70 @@ static void test_unmerge(void) munmap(map, size); } =20 +static void test_unmerge_zero_pages(void) +{ + const unsigned int size =3D 2 * MiB; + char *map; + unsigned int offs; + unsigned long pages_expected; + + ksft_print_msg("[RUN] %s\n", __func__); + + if (proc_self_ksm_stat_fd < 0) { + ksft_test_result_skip("open(\"/proc/self/ksm_stat\") failed\n"); + return; + } + if (ksm_use_zero_pages_fd < 0) { + ksft_test_result_skip("open \"/sys/kernel/mm/ksm/use_zero_pages\" failed= \n"); + return; + } + if (write(ksm_use_zero_pages_fd, "1", 1) !=3D 1) { + ksft_test_result_skip("write \"/sys/kernel/mm/ksm/use_zero_pages\" faile= d\n"); + return; + } + + /* Let KSM deduplicate zero pages. */ + map =3D mmap_and_merge_range(0x00, size, false); + if (map =3D=3D MAP_FAILED) + return; + + /* Check if ksm_zero_pages is updated correctly after KSM merging */ + pages_expected =3D size / pagesize; + if (pages_expected !=3D get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after merging\n"); + goto unmap; + } + + /* Try to unmerge half of the region */ + if (madvise(map, size / 2, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto unmap; + } + + /* Check if ksm_zero_pages is updated correctly after unmerging */ + pages_expected /=3D 2; + if (pages_expected !=3D get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after unmerging\n"); + goto unmap; + } + + /* Trigger unmerging of the other half by writing to the pages. */ + for (offs =3D size / 2; offs < size; offs +=3D pagesize) + *((unsigned int *)&map[offs]) =3D offs; + + /* Now we should have no zeropages remaining. */ + if (get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after write fault\n"); + goto unmap; + } + + /* Check if ksm zero pages are really unmerged */ + ksft_test_result(!range_maps_duplicates(map, size), + "KSM zero pages were unmerged\n"); +unmap: + munmap(map, size); +} + static void test_unmerge_discarded(void) { const unsigned int size =3D 2 * MiB; @@ -358,7 +451,7 @@ static void test_prctl_unmerge(void) =20 int main(int argc, char **argv) { - unsigned int tests =3D 5; + unsigned int tests =3D 6; int err; =20 #ifdef __NR_userfaultfd @@ -379,8 +472,11 @@ int main(int argc, char **argv) pagemap_fd =3D open("/proc/self/pagemap", O_RDONLY); if (pagemap_fd < 0) ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n"); + proc_self_ksm_stat_fd =3D open("/proc/self/ksm_stat", O_RDONLY); + ksm_use_zero_pages_fd =3D open("/sys/kernel/mm/ksm/use_zero_pages", O_RDW= R); =20 test_unmerge(); + test_unmerge_zero_pages(); test_unmerge_discarded(); #ifdef __NR_userfaultfd test_unmerge_uffd_wp(); --=20 2.15.2