From nobody Sun Feb 8 17:21:09 2026 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 8AB13C7EE2A for ; Mon, 22 May 2023 11:18:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232892AbjEVLSS (ORCPT ); Mon, 22 May 2023 07:18:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233255AbjEVLQb (ORCPT ); Mon, 22 May 2023 07:16:31 -0400 Received: from ubuntu20 (unknown [193.203.214.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95C482690 for ; Mon, 22 May 2023 04:11:07 -0700 (PDT) Received: by ubuntu20 (Postfix, from userid 1003) id 23C14E1ED8; Mon, 22 May 2023 18:54:35 +0800 (CST) From: Yang Yang To: akpm@linux-foundation.org, david@redhat.com Cc: yang.yang29@zte.com.cn, imbrenda@linux.ibm.com, jiang.xuexin@zte.com.cn, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn, xu.xin.sc@gmail.com, xu.xin16@zte.com.cn Subject: [PATCH v8 6/6] selftest: add a testcase of ksm zero pages Date: Mon, 22 May 2023 18:54:33 +0800 Message-Id: <20230522105433.4277-1-yang.yang29@zte.com.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <202305221842587200002@zte.com.cn> References: <202305221842587200002@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 three 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; (3) whether ksm zero pages are really unmerged. Signed-off-by: xu xin Cc: Claudio Imbrenda Cc: David Hildenbrand Cc: Xuexin Jiang Reviewed-by: Xiaokai Ran Reviewed-by: Yang Yang --- tools/testing/selftests/mm/ksm_functional_tests.c | 75 +++++++++++++++++++= ++++ 1 file changed, 75 insertions(+) diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/test= ing/selftests/mm/ksm_functional_tests.c index 26853badae70..9b7fb94ed64f 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 ksm_zero_pages_fd; +static int ksm_use_zero_pages_fd; static int pagemap_fd; static size_t pagesize; =20 @@ -59,6 +61,21 @@ static bool range_maps_duplicates(char *addr, unsigned l= ong size) return false; } =20 +static long get_ksm_zero_pages(void) +{ + char buf[20]; + ssize_t read_size; + unsigned long ksm_zero_pages; + + read_size =3D pread(ksm_zero_pages_fd, buf, sizeof(buf) - 1, 0); + if (read_size < 0) + return -errno; + buf[read_size] =3D 0; + ksm_zero_pages =3D strtol(buf, NULL, 10); + + return ksm_zero_pages; +} + static long ksm_get_full_scans(void) { char buf[10]; @@ -159,6 +176,61 @@ static void test_unmerge(void) munmap(map, size); } =20 +static inline unsigned long expected_ksm_pages(unsigned long mergeable_siz= e) +{ + return mergeable_size / pagesize; +} + +static void test_unmerge_zero_pages(void) +{ + const unsigned int size =3D 2 * MiB; + char *map; + unsigned long pages_expected; + + ksft_print_msg("[RUN] %s\n", __func__); + + /* Confirm the interfaces*/ + if (ksm_zero_pages_fd < 0) { + ksft_test_result_skip("open(\"/sys/kernel/mm/ksm/ksm_zero_pages\") faile= d\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; + } + + /* Mmap zero pages*/ + map =3D mmap_and_merge_range(0x00, size, false); + if (map =3D=3D MAP_FAILED) + return; + + /* Check if ksm_zero_pages can be update correctly after merging */ + pages_expected =3D expected_ksm_pages(size); + ksft_test_result(pages_expected =3D=3D get_ksm_zero_pages(), + "The count zero_page_sharing was updated after merging\n"); + + /* 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 can be update correctly after unmerging */ + pages_expected =3D expected_ksm_pages(size / 2); + ksft_test_result(pages_expected =3D=3D get_ksm_zero_pages(), + "The count zero_page_sharing was updated after unmerging\n"); + + /* Check if ksm zero pages are really unmerged */ + ksft_test_result(!range_maps_duplicates(map, size / 2), + "KSM zero pages were unmerged\n"); +unmap: + munmap(map, size); +} + static void test_unmerge_discarded(void) { const unsigned int size =3D 2 * MiB; @@ -379,8 +451,11 @@ 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"); + ksm_zero_pages_fd =3D open("/sys/kernel/mm/ksm/ksm_zero_pages", 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