The patch titled
Subject: mm/ksm: test case for prctl fork/exec workflow
has been added to the -mm mm-unstable branch. Its filename is
mm-ksm-test-case-for-prctl-fork-exec-workflow.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-test-case-for-prctl-fork-exec-workflow.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: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: mm/ksm: test case for prctl fork/exec workflow
Date: Fri, 22 Sep 2023 14:11:41 -0700
This adds a new test case to the ksm functional tests to make sure that
the KSM setting is inherited by the child process when doing a fork/exec.
Link: https://lkml.kernel.org/r/20230922211141.320789-3-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Carl Klemm <carl@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/mm/ksm_functional_tests.c | 66 +++++++++++-
1 file changed, 65 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/mm/ksm_functional_tests.c~mm-ksm-test-case-for-prctl-fork-exec-workflow
+++ a/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -26,6 +26,7 @@
#define KiB 1024u
#define MiB (1024 * KiB)
+#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child"
static int mem_fd;
static int ksm_fd;
@@ -479,6 +480,64 @@ 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;
+ pid_t child_pid;
+
+ ksft_print_msg("[RUN] %s\n", __func__);
+
+ ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
+ if (ret < 0 && errno == EINVAL) {
+ ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");
+ return;
+ } else if (ret) {
+ ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");
+ return;
+ }
+
+ child_pid = fork();
+ if (child_pid == -1) {
+ ksft_test_result_skip("fork() failed\n");
+ return;
+ } else if (child_pid == 0) {
+ char *prg_name = "./ksm_functional_tests";
+ char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME };
+
+ execv(prg_name, argv_for_program);
+ return;
+ }
+
+ if (waitpid(child_pid, &status, 0) > 0) {
+ if (WIFEXITED(status)) {
+ status = WEXITSTATUS(status);
+ if (status) {
+ ksft_test_result_fail("KSM not enabled\n");
+ return;
+ }
+ } else {
+ ksft_test_result_fail("program didn't terminate normally\n");
+ return;
+ }
+ } else {
+ ksft_test_result_fail("waitpid() failed\n");
+ return;
+ }
+
+ if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) {
+ ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n");
+ return;
+ }
+
+ ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
+}
+
static void test_prctl_unmerge(void)
{
const unsigned int size = 2 * MiB;
@@ -536,9 +595,13 @@ unmap:
int main(int argc, char **argv)
{
- unsigned int tests = 7;
+ unsigned int tests = 8;
int err;
+ if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
+ exit(ksm_fork_exec_child() == 1 ? 0 : 1);
+ }
+
#ifdef __NR_userfaultfd
tests++;
#endif
@@ -576,6 +639,7 @@ int main(int argc, char **argv)
test_prctl();
test_prctl_fork();
+ test_prctl_fork_exec();
test_prctl_unmerge();
err = ksft_get_fail_cnt();
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
mm-ksm-add-smart-page-scanning-mode.patch
mm-ksm-add-pages_skipped-metric.patch
mm-ksm-document-smart-scan-mode.patch
mm-ksm-document-pages_skipped-sysfs-knob.patch
mm-ksm-support-fork-exec-for-prctl.patch
mm-ksm-test-case-for-prctl-fork-exec-workflow.patch
