1 files changed, 276 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
new file mode 100644
index 000000000000..9bc4591c7b16
--- /dev/null
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * A test for the patch "Allow compaction of unevictable pages".
+ * With this patch we should be able to allocate at least 1/4
+ * of RAM in huge pages. Without the patch much less is
+ * allocated.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "../kselftest.h"
+
+#define MAP_SIZE_MB	100
+#define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
+
+struct map_list {
+	void *map;
+	struct map_list *next;
+};
+
+int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
+{
+	char  buffer[256] = {0};
+	char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
+	FILE *cmdfile = popen(cmd, "r");
+
+	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
+		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
+		return -1;
+	}
+
+	pclose(cmdfile);
+
+	*memfree = atoll(buffer);
+	cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
+	cmdfile = popen(cmd, "r");
+
+	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
+		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
+		return -1;
+	}
+
+	pclose(cmdfile);
+	*hugepagesize = atoll(buffer);
+
+	return 0;
+}
+
+int prereq(void)
+{
+	char allowed;
+	int fd;
+
+	fd = open("/proc/sys/vm/compact_unevictable_allowed",
+		  O_RDONLY | O_NONBLOCK);
+	if (fd < 0) {
+		ksft_print_msg("Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
+			       strerror(errno));
+		return -1;
+	}
+
+	if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
+		ksft_print_msg("Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
+			       strerror(errno));
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+	if (allowed == '1')
+		return 0;
+
+	ksft_print_msg("Compaction isn't allowed\n");
+	return -1;
+}
+
+int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
+		     unsigned long initial_nr_hugepages)
+{
+	unsigned long nr_hugepages_ul;
+	int fd, ret = -1;
+	int compaction_index = 0;
+	char nr_hugepages[20] = {0};
+	char init_nr_hugepages[24] = {0};
+	char target_nr_hugepages[24] = {0};
+	int slen;
+
+	snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
+		 "%lu", initial_nr_hugepages);
+
+	/* We want to test with 80% of available memory. Else, OOM killer comes
+	   in to play */
+	mem_free = mem_free * 0.8;
+
+	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
+	if (fd < 0) {
+		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		ret = -1;
+		goto out;
+	}
+
+	/*
+	 * Request huge pages for about half of the free memory. The Kernel
+	 * will allocate as much as it can, and we expect it will get at least 1/3
+	 */
+	nr_hugepages_ul = mem_free / hugepage_size / 2;
+	snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
+		 "%lu", nr_hugepages_ul);
+
+	slen = strlen(target_nr_hugepages);
+	if (write(fd, target_nr_hugepages, slen) != slen) {
+		ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
+			       nr_hugepages_ul, strerror(errno));
+		goto close_fd;
+	}
+
+	lseek(fd, 0, SEEK_SET);
+
+	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
+		ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		goto close_fd;
+	}
+
+	/* We should have been able to request at least 1/3 rd of the memory in
+	   huge pages */
+	nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
+	if (!nr_hugepages_ul) {
+		ksft_print_msg("ERROR: No memory is available as huge pages\n");
+		goto close_fd;
+	}
+	compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
+
+	lseek(fd, 0, SEEK_SET);
+
+	if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
+	    != strlen(init_nr_hugepages)) {
+		ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		goto close_fd;
+	}
+
+	ksft_print_msg("Number of huge pages allocated = %lu\n",
+		       nr_hugepages_ul);
+
+	if (compaction_index > 3) {
+		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
+			       "as huge pages\n", compaction_index);
+		goto close_fd;
+	}
+
+	ret = 0;
+
+ close_fd:
+	close(fd);
+ out:
+	ksft_test_result(ret == 0, "check_compaction\n");
+	return ret;
+}
+
+int set_zero_hugepages(unsigned long *initial_nr_hugepages)
+{
+	int fd, ret = -1;
+	char nr_hugepages[20] = {0};
+
+	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
+	if (fd < 0) {
+		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		goto out;
+	}
+	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
+		ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		goto close_fd;
+	}
+
+	lseek(fd, 0, SEEK_SET);
+
+	/* Start with the initial condition of 0 huge pages */
+	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
+		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
+			       strerror(errno));
+		goto close_fd;
+	}
+
+	*initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
+	ret = 0;
+
+ close_fd:
+	close(fd);
+
+ out:
+	return ret;
+}
+
+int main(int argc, char **argv)
+{
+	struct rlimit lim;
+	struct map_list *list = NULL, *entry;
+	size_t page_size, i;
+	void *map = NULL;
+	unsigned long mem_free = 0;
+	unsigned long hugepage_size = 0;
+	long mem_fragmentable_MB = 0;
+	unsigned long initial_nr_hugepages;
+
+	ksft_print_header();
+
+	if (prereq() || geteuid())
+		ksft_exit_skip("Prerequisites unsatisfied\n");
+
+	ksft_set_plan(1);
+
+	/* Start the test without hugepages reducing mem_free */
+	if (set_zero_hugepages(&initial_nr_hugepages))
+		ksft_exit_fail();
+
+	lim.rlim_cur = RLIM_INFINITY;
+	lim.rlim_max = RLIM_INFINITY;
+	if (setrlimit(RLIMIT_MEMLOCK, &lim))
+		ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
+
+	page_size = getpagesize();
+
+	if (read_memory_info(&mem_free, &hugepage_size) != 0)
+		ksft_exit_fail_msg("Failed to get meminfo\n");
+
+	mem_fragmentable_MB = mem_free * 0.8 / 1024;
+
+	while (mem_fragmentable_MB > 0) {
+		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
+			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
+		if (map == MAP_FAILED)
+			break;
+
+		entry = malloc(sizeof(struct map_list));
+		if (!entry) {
+			munmap(map, MAP_SIZE);
+			break;
+		}
+		entry->map = map;
+		entry->next = list;
+		list = entry;
+
+		/* Write something (in this case the address of the map) to
+		 * ensure that KSM can't merge the mapped pages
+		 */
+		for (i = 0; i < MAP_SIZE; i += page_size)
+			*(unsigned long *)(map + i) = (unsigned long)map + i;
+
+		mem_fragmentable_MB -= MAP_SIZE_MB;
+	}
+
+	for (entry = list; entry != NULL; entry = entry->next) {
+		munmap(entry->map, MAP_SIZE);
+		if (!entry->next)
+			break;
+		entry = entry->next;
+	}
+
+	if (check_compaction(mem_free, hugepage_size,
+			     initial_nr_hugepages) == 0)
+		ksft_exit_pass();
+
+	ksft_exit_fail();
+}