1 files changed, 79 insertions, 120 deletions

diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index d8bd1911dfc0..ac136f04b8d6 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -38,14 +38,11 @@ enum ksm_merge_mode {
 };
 
 static int mem_fd;
-static int ksm_fd;
-static int ksm_full_scans_fd;
-static int proc_self_ksm_stat_fd;
-static int proc_self_ksm_merging_pages_fd;
-static int ksm_use_zero_pages_fd;
 static int pagemap_fd;
 static size_t pagesize;
 
+static void init_global_file_handles(void);
+
 static bool range_maps_duplicates(char *addr, unsigned long size)
 {
 	unsigned long offs_a, offs_b, pfn_a, pfn_b;
@@ -73,88 +70,6 @@ static bool range_maps_duplicates(char *addr, unsigned long size)
 	return false;
 }
 
-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 = pread(proc_self_ksm_stat_fd, buf, sizeof(buf) - 1, 0);
-	if (read_size < 0)
-		return -errno;
-
-	buf[read_size] = 0;
-
-	substr_ksm_zero = strstr(buf, "ksm_zero_pages");
-	if (!substr_ksm_zero)
-		return 0;
-
-	value_pos = strcspn(substr_ksm_zero, "0123456789");
-	my_ksm_zero_pages = strtol(substr_ksm_zero + value_pos, NULL, 10);
-
-	return my_ksm_zero_pages;
-}
-
-static long get_my_merging_pages(void)
-{
-	char buf[10];
-	ssize_t ret;
-
-	if (proc_self_ksm_merging_pages_fd < 0)
-		return proc_self_ksm_merging_pages_fd;
-
-	ret = pread(proc_self_ksm_merging_pages_fd, buf, sizeof(buf) - 1, 0);
-	if (ret <= 0)
-		return -errno;
-	buf[ret] = 0;
-
-	return strtol(buf, NULL, 10);
-}
-
-static long ksm_get_full_scans(void)
-{
-	char buf[10];
-	ssize_t ret;
-
-	ret = pread(ksm_full_scans_fd, buf, sizeof(buf) - 1, 0);
-	if (ret <= 0)
-		return -errno;
-	buf[ret] = 0;
-
-	return strtol(buf, NULL, 10);
-}
-
-static int ksm_merge(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();
-		if (end_scans < 0)
-			return end_scans;
-	} while (end_scans < start_scans + 2);
-
-	return 0;
-}
-
-static int ksm_unmerge(void)
-{
-	if (write(ksm_fd, "2", 1) != 1)
-		return -errno;
-	return 0;
-}
-
 static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
 				  enum ksm_merge_mode mode)
 {
@@ -163,12 +78,12 @@ static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
 	int ret;
 
 	/* Stabilize accounting by disabling KSM completely. */
-	if (ksm_unmerge()) {
+	if (ksm_stop() < 0) {
 		ksft_print_msg("Disabling (unmerging) KSM failed\n");
 		return err_map;
 	}
 
-	if (get_my_merging_pages() > 0) {
+	if (ksm_get_self_merging_pages() > 0) {
 		ksft_print_msg("Still pages merged\n");
 		return err_map;
 	}
@@ -218,7 +133,7 @@ static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
 	}
 
 	/* Run KSM to trigger merging and wait. */
-	if (ksm_merge()) {
+	if (ksm_start() < 0) {
 		ksft_print_msg("Running KSM failed\n");
 		goto unmap;
 	}
@@ -227,7 +142,7 @@ static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
 	 * Check if anything was merged at all. Ignore the zero page that is
 	 * accounted differently (depending on kernel support).
 	 */
-	if (val && !get_my_merging_pages()) {
+	if (val && !ksm_get_self_merging_pages()) {
 		ksft_print_msg("No pages got merged\n");
 		goto unmap;
 	}
@@ -274,6 +189,7 @@ static void test_unmerge(void)
 	ksft_test_result(!range_maps_duplicates(map, size),
 			 "Pages were unmerged\n");
 unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 
@@ -286,15 +202,12 @@ static void test_unmerge_zero_pages(void)
 
 	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");
+	if (ksm_get_self_zero_pages() < 0) {
+		ksft_test_result_skip("accessing \"/proc/self/ksm_stat\" failed\n");
 		return;
 	}
-	if (write(ksm_use_zero_pages_fd, "1", 1) != 1) {
+
+	if (ksm_use_zero_pages() < 0) {
 		ksft_test_result_skip("write \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n");
 		return;
 	}
@@ -306,7 +219,7 @@ static void test_unmerge_zero_pages(void)
 
 	/* Check if ksm_zero_pages is updated correctly after KSM merging */
 	pages_expected = size / pagesize;
-	if (pages_expected != get_my_ksm_zero_pages()) {
+	if (pages_expected != ksm_get_self_zero_pages()) {
 		ksft_test_result_fail("'ksm_zero_pages' updated after merging\n");
 		goto unmap;
 	}
@@ -319,7 +232,7 @@ static void test_unmerge_zero_pages(void)
 
 	/* Check if ksm_zero_pages is updated correctly after unmerging */
 	pages_expected /= 2;
-	if (pages_expected != get_my_ksm_zero_pages()) {
+	if (pages_expected != ksm_get_self_zero_pages()) {
 		ksft_test_result_fail("'ksm_zero_pages' updated after unmerging\n");
 		goto unmap;
 	}
@@ -329,7 +242,7 @@ static void test_unmerge_zero_pages(void)
 		*((unsigned int *)&map[offs]) = offs;
 
 	/* Now we should have no zeropages remaining. */
-	if (get_my_ksm_zero_pages()) {
+	if (ksm_get_self_zero_pages()) {
 		ksft_test_result_fail("'ksm_zero_pages' updated after write fault\n");
 		goto unmap;
 	}
@@ -338,6 +251,7 @@ static void test_unmerge_zero_pages(void)
 	ksft_test_result(!range_maps_duplicates(map, size),
 			"KSM zero pages were unmerged\n");
 unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 
@@ -366,6 +280,7 @@ static void test_unmerge_discarded(void)
 	ksft_test_result(!range_maps_duplicates(map, size),
 			 "Pages were unmerged\n");
 unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 
@@ -452,6 +367,7 @@ static void test_unmerge_uffd_wp(void)
 close_uffd:
 	close(uffd);
 unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 #endif
@@ -506,27 +422,30 @@ static int test_child_ksm(void)
 
 	/* Test if KSM is enabled for the process. */
 	if (prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) != 1)
-		return -1;
+		return 1;
 
 	/* Test if merge could really happen. */
 	map = __mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_NONE);
 	if (map == MAP_MERGE_FAIL)
-		return -2;
+		return 2;
 	else if (map == MAP_MERGE_SKIP)
-		return -3;
+		return 3;
 
+	ksm_stop();
 	munmap(map, size);
 	return 0;
 }
 
 static void test_child_ksm_err(int status)
 {
-	if (status == -1)
+	if (status == 1)
 		ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
-	else if (status == -2)
+	else if (status == 2)
 		ksft_test_result_fail("Merge in child failed\n");
-	else if (status == -3)
+	else if (status == 3)
 		ksft_test_result_skip("Merge in child skipped\n");
+	else if (status == 4)
+		ksft_test_result_fail("Binary not found\n");
 }
 
 /* Verify that prctl ksm flag is inherited. */
@@ -548,6 +467,7 @@ static void test_prctl_fork(void)
 
 	child_pid = fork();
 	if (!child_pid) {
+		init_global_file_handles();
 		exit(test_child_ksm());
 	} else if (child_pid < 0) {
 		ksft_test_result_fail("fork() failed\n");
@@ -595,10 +515,10 @@ static void test_prctl_fork_exec(void)
 		return;
 	} else if (child_pid == 0) {
 		char *prg_name = "./ksm_functional_tests";
-		char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME };
+		char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME, NULL };
 
 		execv(prg_name, argv_for_program);
-		return;
+		exit(4);
 	}
 
 	if (waitpid(child_pid, &status, 0) > 0) {
@@ -644,6 +564,7 @@ static void test_prctl_unmerge(void)
 	ksft_test_result(!range_maps_duplicates(map, size),
 			 "Pages were unmerged\n");
 unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 
@@ -677,6 +598,47 @@ static void test_prot_none(void)
 	ksft_test_result(!range_maps_duplicates(map, size),
 			 "Pages were unmerged\n");
 unmap:
+	ksm_stop();
+	munmap(map, size);
+}
+
+static void test_fork_ksm_merging_page_count(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+	pid_t child_pid;
+	int status;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_MADVISE);
+	if (map == MAP_FAILED)
+		return;
+
+	child_pid = fork();
+	if (!child_pid) {
+		init_global_file_handles();
+		exit(ksm_get_self_merging_pages());
+	} else if (child_pid < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto unmap;
+	}
+
+	if (waitpid(child_pid, &status, 0) < 0) {
+		ksft_test_result_fail("waitpid() failed\n");
+		goto unmap;
+	}
+
+	status = WEXITSTATUS(status);
+	if (status) {
+		ksft_test_result_fail("ksm_merging_page in child: %d\n", status);
+		goto unmap;
+	}
+
+	ksft_test_result_pass("ksm_merging_pages is not inherited after fork\n");
+
+unmap:
+	ksm_stop();
 	munmap(map, size);
 }
 
@@ -685,24 +647,20 @@ static void init_global_file_handles(void)
 	mem_fd = open("/proc/self/mem", O_RDWR);
 	if (mem_fd < 0)
 		ksft_exit_fail_msg("opening /proc/self/mem failed\n");
-	ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR);
-	if (ksm_fd < 0)
-		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/run\") failed\n");
-	ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY);
-	if (ksm_full_scans_fd < 0)
-		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/full_scans\") failed\n");
+	if (ksm_stop() < 0)
+		ksft_exit_skip("accessing \"/sys/kernel/mm/ksm/run\") failed\n");
+	if (ksm_get_full_scans() < 0)
+		ksft_exit_skip("accessing \"/sys/kernel/mm/ksm/full_scans\") failed\n");
 	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
 	if (pagemap_fd < 0)
 		ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
-	proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
-	proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages",
-						O_RDONLY);
-	ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR);
+	if (ksm_get_self_merging_pages() < 0)
+		ksft_exit_skip("accessing \"/proc/self/ksm_merging_pages\") failed\n");
 }
 
 int main(int argc, char **argv)
 {
-	unsigned int tests = 8;
+	unsigned int tests = 9;
 	int err;
 
 	if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
@@ -734,6 +692,7 @@ int main(int argc, char **argv)
 	test_prctl_fork();
 	test_prctl_fork_exec();
 	test_prctl_unmerge();
+	test_fork_ksm_merging_page_count();
 
 	err = ksft_get_fail_cnt();
 	if (err)