[PATCH v2 4/4] selftests: Add selftests for cachestat

Nhat Pham
2022-12-05T17:52:49Z

Test cachestat on a newly created file, /dev/ files, and /proc/ files.

Signed-off-by: Nhat Pham <nphamcs@gmail.com>
---
MAINTAINERS | 1 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/cachestat/.gitignore | 2 +
tools/testing/selftests/cachestat/Makefile | 7 +
.../selftests/cachestat/test_cachestat.c | 186 ++++++++++++++++++
5 files changed, 197 insertions(+)
create mode 100644 tools/testing/selftests/cachestat/.gitignore
create mode 100644 tools/testing/selftests/cachestat/Makefile
create mode 100644 tools/testing/selftests/cachestat/test_cachestat.c

diff --git a/MAINTAINERS b/MAINTAINERS
index baa081a1fe52..1b8bc6151e86 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4558,6 +4558,7 @@ M: Johannes Weiner <hannes@cmpxchg.org>
L: linux-mm@kvack.org
S: Maintained
F: mm/cachestat.c
+F: tools/testing/selftests/cachestat/test_cachestat.c

CADENCE MIPI-CSI2 BRIDGES
M: Maxime Ripard <mripard@kernel.org>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 0464b2c6c1e4..3cad0b38c5c2 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -4,6 +4,7 @@ TARGETS += amd-pstate
TARGETS += arm64
TARGETS += bpf
TARGETS += breakpoints
+TARGETS += cachestat
TARGETS += capabilities
TARGETS += cgroup
TARGETS += clone3
diff --git a/tools/testing/selftests/cachestat/.gitignore b/tools/testing/selftests/cachestat/.gitignore
new file mode 100644
index 000000000000..d6c30b43a4bb
--- /dev/null
+++ b/tools/testing/selftests/cachestat/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+test_cachestat
diff --git a/tools/testing/selftests/cachestat/Makefile b/tools/testing/selftests/cachestat/Makefile
new file mode 100644
index 000000000000..04e84fd7d8ce
--- /dev/null
+++ b/tools/testing/selftests/cachestat/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS := test_cachestat
+
+CFLAGS += $(KHDR_INCLUDES)
+CFLAGS += -Wall
+
+include ../lib.mk
diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c
new file mode 100644
index 000000000000..120f42ba3a5d
--- /dev/null
+++ b/tools/testing/selftests/cachestat/test_cachestat.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <linux/kernel.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+
+#include "../kselftest.h"
+
+static const char * const dev_files[] = {
+ "/dev/zero", "/dev/null", "/dev/urandom",
+ "/proc/version", "/proc"
+};
+
+/*
+ * Open/create the file at filename, (optionally) write random data to it
+ * (exactly num_pages), then test the cachestat syscall on this file.
+ *
+ * If test_fsync == true, fsync the file, then check the number of dirty
+ * pages.
+ */
+bool test_cachestat(const char *filename, bool write_random, bool create,
+ bool test_fsync, int num_pages, int open_flags, mode_t open_mode)
+{
+ int cachestat_nr = 451;
+ size_t PS = sysconf(_SC_PAGESIZE);
+ int filesize = num_pages * PS;
+ bool ret = true;
+ int random_fd;
+ long syscall_ret;
+ struct cachestat cs;
+
+ int fd = open(filename, open_flags, open_mode);
+
+ if (fd == -1) {
+ ksft_print_msg("Unable to create/open file.\n");
+ goto out;
+ } else {
+ ksft_print_msg("Create/open %s\n", filename);
+ }
+
+ if (write_random) {
+ char data[filesize];
+
+ random_fd = open("/dev/urandom", O_RDONLY);
+
+ if (random_fd < 0) {
+ ksft_print_msg("Unable to access urandom.\n");
+ ret = false;
+ goto out1;
+ } else {
+ int remained = filesize;
+ char *cursor = data;
+
+ while (remained) {
+ ssize_t read_len = read(random_fd, cursor, remained);
+
+ if (read_len <= 0) {
+ ksft_print_msg("Unable to read from urandom.\n");
+ ret = false;
+ goto out2;
+ }
+
+ remained -= read_len;
+ cursor += read_len;
+ }
+
+ /* write random data to fd */
+ remained = filesize;
+ cursor = data;
+ while (remained) {
+ ssize_t write_len = write(fd, cursor, remained);
+
+ if (write_len <= 0) {
+ ksft_print_msg("Unable write random data to file.\n");
+ ret = false;
+ goto out2;
+ }
+
+ remained -= write_len;
+ cursor += write_len;
+ }
+ }
+ }
+
+ syscall_ret = syscall(cachestat_nr, fd, 0, filesize,
+ sizeof(struct cachestat), &cs);
+
+ ksft_print_msg("Cachestat call returned %ld\n", syscall_ret);
+
+ if (syscall_ret) {
+ ksft_print_msg("Cachestat returned non-zero.\n");
+ ret = false;
+
+ if (write_random)
+ goto out2;
+ else
+ goto out1;
+
+ } else {
+ ksft_print_msg(
+ "Using cachestat: Cached: %lu, Dirty: %lu, Writeback: %lu, Evicted: %lu, Recently Evicted: %lu\n",
+ cs.nr_cache, cs.nr_dirty, cs.nr_writeback,
+ cs.nr_evicted, cs.nr_recently_evicted);
+
+ if (write_random) {
+ if (cs.nr_cache + cs.nr_evicted != num_pages) {
+ ksft_print_msg(
+ "Total number of cached and evicted pages is off.\n");
+ ret = false;
+ }
+ }
+ }
+
+ if (test_fsync) {
+ if (fsync(fd)) {
+ ksft_print_msg("fsync fails.\n");
+ ret = false;
+ } else {
+ syscall_ret = syscall(cachestat_nr, fd, 0, filesize,
+ sizeof(struct cachestat), &cs);
+
+ ksft_print_msg("Cachestat call (after fsync) returned %ld\n",
+ syscall_ret);
+
+ if (!syscall_ret) {
+ ksft_print_msg(
+ "Using cachestat: Cached: %lu, Dirty: %lu, Writeback: %lu, Evicted: %lu, Recently Evicted: %lu\n",
+ cs.nr_cache, cs.nr_dirty, cs.nr_writeback,
+ cs.nr_evicted, cs.nr_recently_evicted);
+
+ if (cs.nr_dirty) {
+ ret = false;
+ ksft_print_msg(
+ "Number of dirty should be zero after fsync.\n");
+ }
+ } else {
+ ksft_print_msg("Cachestat (after fsync) returned non-zero.\n");
+ ret = false;
+
+ if (write_random)
+ goto out2;
+ else
+ goto out1;
+ }
+ }
+ }
+
+out2:
+ if (write_random)
+ close(random_fd);
+out1:
+ close(fd);
+
+ if (create)
+ remove(filename);
+out:
+ return ret;
+}
+
+int main(void)
+{
+ for (int i = 0; i < 5; i++) {
+ const char *dev_filename = dev_files[i];
+
+ if (test_cachestat(dev_filename, false, false, false,
+ 4, O_RDONLY, 0400))
+ ksft_test_result_pass("cachestat works with %s\n", dev_filename);
+ else
+ ksft_test_result_fail("cachestat fails with %s\n", dev_filename);
+ }
+
+ if (test_cachestat("tmpfilecachestat", true, true,
+ true, 4, O_CREAT | O_RDWR, 0400 | 0600))
+ ksft_test_result_pass("cachestat works with a normal file\n");
+ else
+ ksft_test_result_fail("cachestat fails with normal file\n");
+
+ return 0;
+}
--
2.30.2