[PATCH 2/2] selftests: add a selftest to verify hugetlb usage in memcg

Nhat Pham
2023-09-26T19:49:56Z

This patch add a new kselftest to demonstrate and verify the new
hugetlb memcg accounting behavior.

Signed-off-by: Nhat Pham <nphamcs@gmail.com>
---
MAINTAINERS | 2 +
tools/testing/selftests/cgroup/.gitignore | 1 +
tools/testing/selftests/cgroup/Makefile | 2 +
.../selftests/cgroup/test_hugetlb_memcg.c | 222 ++++++++++++++++++
4 files changed, 227 insertions(+)
create mode 100644 tools/testing/selftests/cgroup/test_hugetlb_memcg.c

diff --git a/MAINTAINERS b/MAINTAINERS
index bf0f54c24f81..ce9f40bcc2ba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5269,6 +5269,7 @@ S: Maintained
F: mm/memcontrol.c
F: mm/swap_cgroup.c
F: tools/testing/selftests/cgroup/memcg_protection.m
+F: tools/testing/selftests/cgroup/test_hugetlb_memcg.c
F: tools/testing/selftests/cgroup/test_kmem.c
F: tools/testing/selftests/cgroup/test_memcontrol.c

@@ -9652,6 +9653,7 @@ F: include/linux/hugetlb.h
F: mm/hugetlb.c
F: mm/hugetlb_vmemmap.c
F: mm/hugetlb_vmemmap.h
+F: tools/testing/selftests/cgroup/test_hugetlb_memcg.c

HVA ST MEDIA DRIVER
M: Jean-Christophe Trotin <jean-christophe.trotin@foss.st.com>
diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore
index af8c3f30b9c1..2732e0b29271 100644
--- a/tools/testing/selftests/cgroup/.gitignore
+++ b/tools/testing/selftests/cgroup/.gitignore
@@ -7,4 +7,5 @@ test_kill
test_cpu
test_cpuset
test_zswap
+test_hugetlb_memcg
wait_inotify
diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile
index c27f05f6ce9b..00b441928909 100644
--- a/tools/testing/selftests/cgroup/Makefile
+++ b/tools/testing/selftests/cgroup/Makefile
@@ -14,6 +14,7 @@ TEST_GEN_PROGS += test_kill
TEST_GEN_PROGS += test_cpu
TEST_GEN_PROGS += test_cpuset
TEST_GEN_PROGS += test_zswap
+TEST_GEN_PROGS += test_hugetlb_memcg

LOCAL_HDRS += $(selfdir)/clone3/clone3_selftests.h $(selfdir)/pidfd/pidfd.h

@@ -27,3 +28,4 @@ $(OUTPUT)/test_kill: cgroup_util.c
$(OUTPUT)/test_cpu: cgroup_util.c
$(OUTPUT)/test_cpuset: cgroup_util.c
$(OUTPUT)/test_zswap: cgroup_util.c
+$(OUTPUT)/test_hugetlb_memcg: cgroup_util.c
diff --git a/tools/testing/selftests/cgroup/test_hugetlb_memcg.c b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c
new file mode 100644
index 000000000000..9651f6af6914
--- /dev/null
+++ b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <linux/limits.h>
+#include <sys/mman.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include "../kselftest.h"
+#include "cgroup_util.h"
+
+#define ADDR ((void *)(0x0UL))
+#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
+/* mapping 8 MBs == 4 hugepages */
+#define LENGTH (8UL*1024*1024)
+#define PROTECTION (PROT_READ | PROT_WRITE)
+
+/* borrowed from mm/hmm-tests.c */
+static long get_hugepage_size(void)
+{
+ int fd;
+ char buf[2048];
+ int len;
+ char *p, *q, *path = "/proc/meminfo", *tag = "Hugepagesize:";
+ long val;
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0) {
+ /* Error opening the file */
+ return -1;
+ }
+
+ len = read(fd, buf, sizeof(buf));
+ close(fd);
+ if (len < 0) {
+ /* Error in reading the file */
+ return -1;
+ }
+ if (len == sizeof(buf)) {
+ /* Error file is too large */
+ return -1;
+ }
+ buf[len] = '\0';
+
+ /* Search for a tag if provided */
+ if (tag) {
+ p = strstr(buf, tag);
+ if (!p)
+ return -1; /* looks like the line we want isn't there */
+ p += strlen(tag);
+ } else
+ p = buf;
+
+ val = strtol(p, &q, 0);
+ if (*q != ' ') {
+ /* Error parsing the file */
+ return -1;
+ }
+
+ return val;
+}
+
+static int set_file(const char *path, long value)
+{
+ FILE *file;
+ int ret;
+
+ file = fopen(path, "w");
+ if (!file)
+ return -1;
+ ret = fprintf(file, "%ld\n", value);
+ fclose(file);
+ return ret;
+}
+
+static int set_nr_hugepages(long value)
+{
+ return set_file("/proc/sys/vm/nr_hugepages", value);
+}
+
+static unsigned int check_first(char *addr)
+{
+ return *(unsigned int *)addr;
+}
+
+static void write_data(char *addr)
+{
+ unsigned long i;
+
+ for (i = 0; i < LENGTH; i++)
+ *(addr + i) = (char)i;
+}
+
+static int hugetlb_test_program(const char *cgroup, void *arg)
+{
+ char *test_group = (char *)arg;
+ void *addr;
+ long old_current, expected_current, current;
+ int ret = EXIT_FAILURE;
+
+ old_current = cg_read_long(test_group, "memory.current");
+
+ addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0);
+ if (addr == MAP_FAILED) {
+ ksft_print_msg("fail to mmap.\n");
+ return EXIT_FAILURE;
+ }
+ current = cg_read_long(test_group, "memory.current");
+ if (current - old_current >= MB(2)) {
+ ksft_print_msg("mmap should not increase hugepage usage.\n");
+ goto out_failed_munmap;
+ }
+ old_current = current;
+
+ /* read the first page */
+ check_first(addr);
+ expected_current = old_current + MB(2);
+ current = cg_read_long(test_group, "memory.current");
+ if (!values_close(expected_current, current, 1)) {
+ ksft_print_msg("memory usage should increase by around 2MB.\n");
+ goto out_failed_munmap;
+ }
+
+ /* write to the whole range */
+ write_data(addr);
+ current = cg_read_long(test_group, "memory.current");
+ expected_current = old_current + MB(8);
+ if (!values_close(expected_current, current, 1)) {
+ ksft_print_msg("memory usage should increase by around 8MB.\n");
+ goto out_failed_munmap;
+ }
+
+ /* unmap the whole range */
+ munmap(addr, LENGTH);
+ current = cg_read_long(test_group, "memory.current");
+ expected_current = old_current;
+ if (!values_close(expected_current, current, 1)) {
+ ksft_print_msg("memory usage should go back down.\n");
+ return ret;
+ }
+
+ ret = EXIT_SUCCESS;
+ return ret;
+
+out_failed_munmap:
+ munmap(addr, LENGTH);
+ return ret;
+}
+
+static int test_hugetlb_memcg(char *root)
+{
+ int ret = KSFT_FAIL;
+ char *test_group;
+ long old_current, expected_current, current;
+
+ test_group = cg_name(root, "hugetlb_memcg_test");
+
+ if (!test_group || cg_create(test_group)) {
+ ksft_print_msg("fail to create cgroup.\n");
+ goto out;
+ }
+
+ if (cg_write(test_group, "memory.max", "100M")) {
+ ksft_print_msg("fail to set cgroup memory limit.\n");
+ goto out;
+ }
+
+ /* disable swap */
+ if (cg_write(test_group, "memory.swap.max", "0")) {
+ ksft_print_msg("fail to disable swap.\n");
+ goto out;
+ }
+ old_current = cg_read_long(test_group, "memory.current");
+
+ set_nr_hugepages(20);
+ current = cg_read_long(test_group, "memory.current");
+ expected_current = old_current;
+ if (!values_close(expected_current, current, 10)) {
+ ksft_print_msg(
+ "memory usage should not increase after setting nr_hugepages.\n");
+ goto out;
+ }
+
+ if (!cg_run(test_group, hugetlb_test_program, (void *)test_group))
+ ret = KSFT_PASS;
+out:
+ cg_destroy(test_group);
+ free(test_group);
+ return ret;
+}
+
+int main(int argc, char **argv)
+{
+ char root[PATH_MAX];
+ int ret = EXIT_SUCCESS;
+
+ /* Unit is kB! */
+ if (get_hugepage_size() != 2048) {
+ ksft_print_msg("test_hugetlb_memcg requires 2MB hugepages\n");
+ ksft_test_result_skip("test_hugetlb_memcg\n");
+ return ret;
+ }
+
+ if (cg_find_unified_root(root, sizeof(root)))
+ ksft_exit_skip("cgroup v2 isn't mounted\n");
+
+ switch (test_hugetlb_memcg(root)) {
+ case KSFT_PASS:
+ ksft_test_result_pass("test_hugetlb_memcg\n");
+ break;
+ case KSFT_SKIP:
+ ksft_test_result_skip("test_hugetlb_memcg\n");
+ break;
+ default:
+ ret = EXIT_FAILURE;
+ ksft_test_result_fail("test_hugetlb_memcg\n");
+ break;
+ }
+
+ return ret;
+}
--
2.34.1