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Fri, 10 Feb 2023 09:21:57 +0800 (CST) Date: Fri, 10 Feb 2023 09:21:57 +0800 (CST) X-Zmail-TransId: 2b0363e59c35ffffffffa055065e X-Mailer: Zmail v1.0 Message-ID: <202302100921574141612@zte.com.cn> Mime-Version: 1.0 From: To: Cc: , , , , , , , , Subject: =?UTF-8?B?W1BBVENIIHY2IDYvNl0gc2VsZnRlc3Q6IGFkZCB0ZXN0aW5nIHVuc2hhcmluZyBhbmQgY291bnRpbmcga3NtIHplcm8KIHBhZ2U=?= Content-Type: text/plain; charset="UTF-8" X-MAIL:mse-fl2.zte.com.cn 31A1LuBR026416 X-Fangmail-Gw-Spam-Type: 0 X-Fangmail-Anti-Spam-Filtered: true X-Fangmail-MID-QID: 63E59C3A.001/4PCbYk6QnNz501Qf X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7484E100010 X-Stat-Signature: ufj614gfabmw6pxmscs9q33zpruh4geg X-HE-Tag: 1675992125-365246 X-HE-Meta: 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 ehDRoo3I hnr3q06LvzQLFEgnHLtu4Lu9qIaCagFWbxGrVxrbRdK0BanFU8LtgVG53C59wylcci8bB4+5Eb+f6ZRclketj4i0MMisMiM80XXnOcEQv27KighHhMPGzypJytD4l3z7SoNEWFNBGV8gT/2+rDSxPLwF1mSHLw5o0//LGsH66t3aXNDsWh7Bn7wzpZGRYZjeeS8o37C57XsIjErwM4wbXzU1MC0hQQVAh45rcg5h46CQnaeqwGkAv110ROETkF0OO2gZ3rOw1PYMcLGL3zKuwSBnRTXh+9roxF7AoGST05h5hVIqmJ/YoYqeIP9ULl+/Z3lIJFMdwlz1sooUYdJzrMyEvTHK0ou6MLVK/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 page can react correctly to cow (copy on write); 2) whether the count of ksm zero page can react correctly to unmerge; 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 v5->v6: According to David's suggestions, the following changes are made: 1) Rename check_ksm_zero_pages_count() -> ksm_get_zero_pages(), and do the comparison outside. 2) Open all global fd from main() rather than the test case. 3) Remove COW-related test codes and focus on explicit unmerging here. 4) Add some coments to explain why wait_two_full_scans is required. 5) Clean up some unneed changes. v4->v5: fix error of "} while (end_scans < start_scans + 20);" to "} while (end_scans < start_scans + 2);" in wait_two_full_scans(). --- tools/testing/selftests/vm/ksm_functional_tests.c | 96 ++++++++++++++++++++++- 1 file changed, 92 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/vm/ksm_functional_tests.c b/tools/testing/selftests/vm/ksm_functional_tests.c index b11b7e5115dc..3033cd6ed3b4 100644 --- a/tools/testing/selftests/vm/ksm_functional_tests.c +++ b/tools/testing/selftests/vm/ksm_functional_tests.c @@ -24,9 +24,12 @@ #define KiB 1024u #define MiB (1024 * KiB) +#define PageSize (4 * KiB) 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; @@ -57,6 +60,21 @@ static bool range_maps_duplicates(char *addr, unsigned long size) return false; } +static long ksm_get_zero_pages(void) +{ + char buf[20]; + ssize_t read_size; + unsigned long ksm_zero_pages; + + read_size = pread(ksm_zero_pages_fd, buf, sizeof(buf) - 1, 0); + if (read_size < 0) + return -errno; + buf[read_size] = 0; + ksm_zero_pages = strtol(buf, NULL, 10); + + return ksm_zero_pages; +} + static long ksm_get_full_scans(void) { char buf[10]; @@ -70,15 +88,12 @@ static long ksm_get_full_scans(void) return strtol(buf, NULL, 10); } -static int ksm_merge(void) +static int wait_two_full_scans(void) { long start_scans, end_scans; - /* Wait for two full scans such that any possible merging happened. */ start_scans = ksm_get_full_scans(); if (start_scans < 0) - return start_scans; - if (write(ksm_fd, "1", 1) != 1) return -errno; do { end_scans = ksm_get_full_scans(); @@ -89,6 +104,34 @@ static int ksm_merge(void) return 0; } +static inline int ksm_merge(void) +{ + /* Wait for two full scans such that any possible merging happened. */ + if (write(ksm_fd, "1", 1) != 1) + return -errno; + + return wait_two_full_scans(); +} + +static int unmerge_zero_page(char *start, unsigned long size) +{ + int ret; + + ret = madvise(start, size, MADV_UNMERGEABLE); + if (ret) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + return ret; + } + + /* + * Wait for two full scans such that any possible unmerging of zero + * pages happened. Why? Because the unmerge action of zero pages is not + * done in the context of madvise(), but in the context of + * unshare_zero_pages() of the ksmd thread. + */ + return wait_two_full_scans(); +} + static char *mmap_and_merge_range(char val, unsigned long size) { char *map; @@ -146,6 +189,48 @@ static void test_unmerge(void) munmap(map, size); } +static void test_unmerge_zero_pages(void) +{ + const unsigned int size = 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/zero_pages_sharing\") 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) != 1) { + ksft_test_result_skip("write \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n"); + return; + } + + /* Mmap zero pages*/ + map = mmap_and_merge_range(0x00, size); + if (map == MAP_FAILED) + return; + + if (unmerge_zero_page(map + size / 2, size / 2)) + goto unmap; + + /* Check if zero_pages_sharing can be update correctly when unmerge */ + pages_expected = (size / 2) / PageSize; + ksft_test_result(pages_expected == ksm_get_zero_pages(), + "zero page count react to unmerge\n"); + + /* Check if ksm zero pages are really unmerged */ + ksft_test_result(!range_maps_duplicates(map + size / 2, size / 2), + "KSM zero pages were unmerged\n"); +unmap: + munmap(map, size); +} + static void test_unmerge_discarded(void) { const unsigned int size = 2 * MiB; @@ -264,8 +349,11 @@ int main(int argc, char **argv) pagemap_fd = open("/proc/self/pagemap", O_RDONLY); if (pagemap_fd < 0) ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n"); + ksm_zero_pages_fd = open("/sys/kernel/mm/ksm/zero_pages_sharing", O_RDONLY); + ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR); test_unmerge(); + test_unmerge_zero_pages(); test_unmerge_discarded(); #ifdef __NR_userfaultfd test_unmerge_uffd_wp(); -- 2.15.2