The patch titled
Subject: selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec
has been added to the -mm mm-unstable branch. Its filename is
selftest-mm-ksm_functional_tests-extend-test-case-for-ksm-fork-exec.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftest-mm-ksm_functional_tests-extend-test-case-for-ksm-fork-exec.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jinjiang Tu <tujinjiang@xxxxxxxxxx>
Subject: selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec
Date: Thu, 28 Mar 2024 19:10:10 +0800
This extends test_prctl_fork() and test_prctl_fork_exec() to make sure
that deduplication really happens, instead of only testing the
MMF_VM_MERGE_ANY flag is set.
Link: https://lkml.kernel.org/r/20240328111010.1502191-4-tujinjiang@xxxxxxxxxx
Signed-off-by: Jinjiang Tu <tujinjiang@xxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Stefan Roesch <shr@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/mm/ksm_functional_tests.c | 49 +++++++++---
1 file changed, 38 insertions(+), 11 deletions(-)
--- a/tools/testing/selftests/mm/ksm_functional_tests.c~selftest-mm-ksm_functional_tests-extend-test-case-for-ksm-fork-exec
+++ a/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -475,6 +475,36 @@ static void test_prctl(void)
ksft_test_result_pass("Setting/clearing PR_SET_MEMORY_MERGE works\n");
}
+static int test_child_ksm(void)
+{
+ const unsigned int size = 2 * MiB;
+ char *map;
+
+ /* Test if KSM is enabled for the process. */
+ if (prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) != 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;
+ else if (map == MAP_MERGE_SKIP)
+ return -3;
+
+ munmap(map, size);
+ return 0;
+}
+
+static void test_child_ksm_err(int status)
+{
+ if (status == -1)
+ ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
+ else if (status == -2)
+ ksft_test_result_fail("Merge in child failed\n");
+ else if (status == -3)
+ ksft_test_result_skip("Merge in child skiped\n");
+}
+
/* Verify that prctl ksm flag is inherited. */
static void test_prctl_fork(void)
{
@@ -494,7 +524,7 @@ static void test_prctl_fork(void)
child_pid = fork();
if (!child_pid) {
- exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0));
+ exit(test_child_ksm());
} else if (child_pid < 0) {
ksft_test_result_fail("fork() failed\n");
return;
@@ -503,8 +533,11 @@ static void test_prctl_fork(void)
if (waitpid(child_pid, &status, 0) < 0) {
ksft_test_result_fail("waitpid() failed\n");
return;
- } else if (WEXITSTATUS(status) != 1) {
- ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
+ }
+
+ status = WEXITSTATUS(status);
+ if (status) {
+ test_child_ksm_err(status);
return;
}
@@ -516,12 +549,6 @@ static void test_prctl_fork(void)
ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
}
-static int ksm_fork_exec_child(void)
-{
- /* Test if KSM is enabled for the process. */
- return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 1;
-}
-
static void test_prctl_fork_exec(void)
{
int ret, status;
@@ -554,7 +581,7 @@ static void test_prctl_fork_exec(void)
if (WIFEXITED(status)) {
status = WEXITSTATUS(status);
if (status) {
- ksft_test_result_fail("KSM not enabled\n");
+ test_child_ksm_err(status);
return;
}
} else {
@@ -635,7 +662,7 @@ int main(int argc, char **argv)
int err;
if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
- exit(ksm_fork_exec_child() == 1 ? 0 : 1);
+ exit(test_child_ksm());
}
#ifdef __NR_userfaultfd
_
Patches currently in -mm which might be from tujinjiang@xxxxxxxxxx are
mm-ksm-fix-ksm-exec-support-for-prctl.patch
selftest-mm-ksm_functional_tests-refactor-mmap_and_merge_range.patch
selftest-mm-ksm_functional_tests-extend-test-case-for-ksm-fork-exec.patch
