1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *
  4 * A test for the patch "Allow compaction of unevictable pages".
  5 * With this patch we should be able to allocate at least 1/4
  6 * of RAM in huge pages. Without the patch much less is
  7 * allocated.
  8 */
  9
 10#include <stdio.h>
 11#include <stdlib.h>
 12#include <sys/mman.h>
 13#include <sys/resource.h>
 14#include <fcntl.h>
 15#include <errno.h>
 16#include <unistd.h>
 17#include <string.h>
 18
 19#include "../kselftest.h"
 20
 21#define MAP_SIZE_MB	100
 22#define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
 23
 24struct map_list {
 25	void *map;
 26	struct map_list *next;
 27};
 28
 29int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
 30{
 31	char  buffer[256] = {0};
 32	char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
 33	FILE *cmdfile = popen(cmd, "r");
 34
 35	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
 36		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
 37		return -1;
 38	}
 39
 40	pclose(cmdfile);
 41
 42	*memfree = atoll(buffer);
 43	cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
 44	cmdfile = popen(cmd, "r");
 45
 46	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
 47		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
 48		return -1;
 49	}
 50
 51	pclose(cmdfile);
 52	*hugepagesize = atoll(buffer);
 53
 54	return 0;
 55}
 56
 57int prereq(void)
 58{
 59	char allowed;
 60	int fd;
 61
 62	fd = open("/proc/sys/vm/compact_unevictable_allowed",
 63		  O_RDONLY | O_NONBLOCK);
 64	if (fd < 0) {
 65		ksft_print_msg("Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
 66			       strerror(errno));
 67		return -1;
 68	}
 69
 70	if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
 71		ksft_print_msg("Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
 72			       strerror(errno));
 73		close(fd);
 74		return -1;
 75	}
 76
 77	close(fd);
 78	if (allowed == '1')
 79		return 0;
 80
 81	ksft_print_msg("Compaction isn't allowed\n");
 82	return -1;
 83}
 84
 85int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
 86		     unsigned long initial_nr_hugepages)
 87{
 88	unsigned long nr_hugepages_ul;
 89	int fd, ret = -1;
 90	int compaction_index = 0;
 91	char nr_hugepages[20] = {0};
 92	char init_nr_hugepages[24] = {0};
 93
 94	snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
 95		 "%lu", initial_nr_hugepages);
 96
 97	/* We want to test with 80% of available memory. Else, OOM killer comes
 98	   in to play */
 99	mem_free = mem_free * 0.8;
100
101	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
102	if (fd < 0) {
103		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
104			       strerror(errno));
105		ret = -1;
106		goto out;
107	}
108
109	/* Request a large number of huge pages. The Kernel will allocate
110	   as much as it can */
111	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
112		ksft_print_msg("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
113			       strerror(errno));
114		goto close_fd;
115	}
116
117	lseek(fd, 0, SEEK_SET);
118
119	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
120		ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
121			       strerror(errno));
122		goto close_fd;
123	}
124
125	/* We should have been able to request at least 1/3 rd of the memory in
126	   huge pages */
127	nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
128	if (!nr_hugepages_ul) {
129		ksft_print_msg("ERROR: No memory is available as huge pages\n");
130		goto close_fd;
131	}
132	compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
133
134	lseek(fd, 0, SEEK_SET);
135
136	if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
137	    != strlen(init_nr_hugepages)) {
138		ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
139			       strerror(errno));
140		goto close_fd;
141	}
142
143	ksft_print_msg("Number of huge pages allocated = %lu\n",
144		       nr_hugepages_ul);
145
146	if (compaction_index > 3) {
147		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
148			       "as huge pages\n", compaction_index);
149		goto close_fd;
150	}
151
152	ret = 0;
153
154 close_fd:
155	close(fd);
156 out:
157	ksft_test_result(ret == 0, "check_compaction\n");
158	return ret;
159}
160
161int set_zero_hugepages(unsigned long *initial_nr_hugepages)
162{
163	int fd, ret = -1;
164	char nr_hugepages[20] = {0};
165
166	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
167	if (fd < 0) {
168		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
169			       strerror(errno));
170		goto out;
171	}
172	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
173		ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
174			       strerror(errno));
175		goto close_fd;
176	}
177
178	lseek(fd, 0, SEEK_SET);
179
180	/* Start with the initial condition of 0 huge pages */
181	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
182		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
183			       strerror(errno));
184		goto close_fd;
185	}
186
187	*initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
188	ret = 0;
189
190 close_fd:
191	close(fd);
192
193 out:
194	return ret;
195}
196
197int main(int argc, char **argv)
198{
199	struct rlimit lim;
200	struct map_list *list = NULL, *entry;
201	size_t page_size, i;
202	void *map = NULL;
203	unsigned long mem_free = 0;
204	unsigned long hugepage_size = 0;
205	long mem_fragmentable_MB = 0;
206	unsigned long initial_nr_hugepages;
207
208	ksft_print_header();
209
210	if (prereq() || geteuid())
211		ksft_exit_skip("Prerequisites unsatisfied\n");
212
213	ksft_set_plan(1);
214
215	/* Start the test without hugepages reducing mem_free */
216	if (set_zero_hugepages(&initial_nr_hugepages))
217		ksft_exit_fail();
218
219	lim.rlim_cur = RLIM_INFINITY;
220	lim.rlim_max = RLIM_INFINITY;
221	if (setrlimit(RLIMIT_MEMLOCK, &lim))
222		ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
223
224	page_size = getpagesize();
225
226	if (read_memory_info(&mem_free, &hugepage_size) != 0)
227		ksft_exit_fail_msg("Failed to get meminfo\n");
228
229	mem_fragmentable_MB = mem_free * 0.8 / 1024;
230
231	while (mem_fragmentable_MB > 0) {
232		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
233			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
234		if (map == MAP_FAILED)
235			break;
236
237		entry = malloc(sizeof(struct map_list));
238		if (!entry) {
239			munmap(map, MAP_SIZE);
240			break;
241		}
242		entry->map = map;
243		entry->next = list;
244		list = entry;
245
246		/* Write something (in this case the address of the map) to
247		 * ensure that KSM can't merge the mapped pages
248		 */
249		for (i = 0; i < MAP_SIZE; i += page_size)
250			*(unsigned long *)(map + i) = (unsigned long)map + i;
251
252		mem_fragmentable_MB -= MAP_SIZE_MB;
253	}
254
255	for (entry = list; entry != NULL; entry = entry->next) {
256		munmap(entry->map, MAP_SIZE);
257		if (!entry->next)
258			break;
259		entry = entry->next;
260	}
261
262	if (check_compaction(mem_free, hugepage_size,
263			     initial_nr_hugepages) == 0)
264		ksft_exit_pass();
265
266	ksft_exit_fail();
267}