[PATCH 3/4] selftests/ksm: consolidate ksm_stat readers into ksm_get_self_stat()
From: Xu Xin (vivo)
Date: Tue Nov 10 2026 - 03:11:38 EST
ksm_get_self_zero_pages() and ksm_get_self_merging_pages() both read
/proc/self/ksm_stat and differ only in the key they look up. Replace
them with a single ksm_get_self_stat(key) helper in vm_util.c, which
reads one value from /proc/self/ksm_stat by key name and accepts only
the keys used by the tests.
This is a pure refactor with no functional change; it prepares for a
new test that also needs to read ksm_rmap_items from /proc/self/ksm_stat.
No functional change intended.
Signed-off-by: Xu Xin (vivo) <xu.xin@xxxxxxxxx>
---
.../selftests/mm/ksm_functional_tests.c | 18 ++++-----
tools/testing/selftests/mm/vm_util.c | 40 ++++++-------------
tools/testing/selftests/mm/vm_util.h | 3 +-
3 files changed, 22 insertions(+), 39 deletions(-)
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index 135191f99962..2ffb97ae3120 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -85,7 +85,7 @@ static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
return err_map;
}
- if (ksm_get_self_merging_pages() > 0) {
+ if (ksm_get_self_stat("ksm_merging_pages") > 0) {
ksft_print_msg("Still pages merged\n");
return err_map;
}
@@ -144,7 +144,7 @@ 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 && !ksm_get_self_merging_pages()) {
+ if (val && !ksm_get_self_stat("ksm_merging_pages")) {
ksft_print_msg("No pages got merged\n");
goto unmap;
}
@@ -204,7 +204,7 @@ static void test_unmerge_zero_pages(void)
ksft_print_msg("[RUN] %s\n", __func__);
- if (ksm_get_self_zero_pages() < 0) {
+ if (ksm_get_self_stat("ksm_zero_pages") < 0) {
ksft_test_result_skip("accessing \"/proc/self/ksm_stat\" failed\n");
return;
}
@@ -221,7 +221,7 @@ 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 != ksm_get_self_zero_pages()) {
+ if (pages_expected != ksm_get_self_stat("ksm_zero_pages")) {
ksft_test_result_fail("'ksm_zero_pages' updated after merging\n");
goto unmap;
}
@@ -234,7 +234,7 @@ static void test_unmerge_zero_pages(void)
/* Check if ksm_zero_pages is updated correctly after unmerging */
pages_expected /= 2;
- if (pages_expected != ksm_get_self_zero_pages()) {
+ if (pages_expected != ksm_get_self_stat("ksm_zero_pages")) {
ksft_test_result_fail("'ksm_zero_pages' updated after unmerging\n");
goto unmap;
}
@@ -244,7 +244,7 @@ static void test_unmerge_zero_pages(void)
*((unsigned int *)&map[offs]) = offs;
/* Now we should have no zeropages remaining. */
- if (ksm_get_self_zero_pages()) {
+ if (ksm_get_self_stat("ksm_zero_pages")) {
ksft_test_result_fail("'ksm_zero_pages' updated after write fault\n");
goto unmap;
}
@@ -671,7 +671,7 @@ static void test_fork_ksm_merging_page_count(void)
child_pid = fork();
if (!child_pid) {
init_global_file_handles();
- exit(ksm_get_self_merging_pages());
+ exit(ksm_get_self_stat("ksm_merging_pages"));
} else if (child_pid < 0) {
ksft_test_result_fail("fork() failed\n");
goto unmap;
@@ -771,7 +771,7 @@ static void test_merge_aged_pairs(void)
goto unmap;
}
- ksft_test_result(ksm_get_self_merging_pages() == 2 * pairs,
+ ksft_test_result(ksm_get_self_stat("ksm_merging_pages") == 2 * pairs,
"Pages aged by smart scan got merged\n");
unmap:
ksm_stop();
@@ -793,7 +793,7 @@ static void init_global_file_handles(void)
pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
if (pagemap_fd < 0)
ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
- if (ksm_get_self_merging_pages() < 0)
+ if (ksm_get_self_stat("ksm_merging_pages") < 0)
ksft_exit_skip("accessing \"/proc/self/ksm_merging_pages\") failed\n");
pages_to_scan_fd = open("/sys/kernel/mm/ksm/pages_to_scan", O_RDWR);
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index f26f9e4bfdbe..8f1ee1f81e36 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -904,14 +904,20 @@ bool detect_huge_zeropage(void)
return enabled;
}
-long ksm_get_self_zero_pages(void)
+long ksm_get_self_stat(const char *key)
{
int proc_self_ksm_stat_fd;
char buf[200];
- char *substr_ksm_zero;
+ char *substr;
size_t value_pos;
ssize_t read_size;
+ /* Only the keys actually used by the tests are accepted. */
+ if (strcmp(key, "ksm_rmap_items") &&
+ strcmp(key, "ksm_zero_pages") &&
+ strcmp(key, "ksm_merging_pages"))
+ return -EINVAL;
+
proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
if (proc_self_ksm_stat_fd < 0)
return -errno;
@@ -925,34 +931,12 @@ long ksm_get_self_zero_pages(void)
buf[read_size] = 0;
- substr_ksm_zero = strstr(buf, "ksm_zero_pages");
- if (!substr_ksm_zero)
+ substr = strstr(buf, key);
+ if (!substr)
return 0;
- value_pos = strcspn(substr_ksm_zero, "0123456789");
- return strtol(substr_ksm_zero + value_pos, NULL, 10);
-}
-
-long ksm_get_self_merging_pages(void)
-{
- int proc_self_ksm_merging_pages_fd;
- char buf[10];
- ssize_t ret;
-
- proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages",
- O_RDONLY);
- if (proc_self_ksm_merging_pages_fd < 0)
- return -errno;
-
- ret = pread(proc_self_ksm_merging_pages_fd, buf, sizeof(buf) - 1, 0);
- close(proc_self_ksm_merging_pages_fd);
- if (ret < 0)
- return -errno;
- if (!ret)
- return -EIO;
- buf[ret] = 0;
-
- return strtol(buf, NULL, 10);
+ value_pos = strcspn(substr, "0123456789");
+ return strtol(substr + value_pos, NULL, 10);
}
long ksm_get_full_scans(void)
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index ab1325dc6580..2b25a9eab30c 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -159,8 +159,7 @@ static inline int sz2ord(size_t size, size_t pagesize)
void *sys_mremap(void *old_address, unsigned long old_size,
unsigned long new_size, int flags, void *new_address);
-long ksm_get_self_zero_pages(void);
-long ksm_get_self_merging_pages(void);
+long ksm_get_self_stat(const char *key);
long ksm_get_full_scans(void);
int ksm_wait_full_scans(long nr);
int ksm_get_smart_scan(void);
--
2.34.1