compaction_test.c

  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	char target_nr_hugepages[24] = {0};
 94	int slen;
 95
 96	snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
 97		 "%lu", initial_nr_hugepages);
 98
 99	/* We want to test with 80% of available memory. Else, OOM killer comes
100	   in to play */
101	mem_free = mem_free * 0.8;
102
103	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
104	if (fd < 0) {
105		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
106			       strerror(errno));
107		ret = -1;
108		goto out;
109	}
110
111	/*
112	 * Request huge pages for about half of the free memory. The Kernel
113	 * will allocate as much as it can, and we expect it will get at least 1/3
114	 */
115	nr_hugepages_ul = mem_free / hugepage_size / 2;
116	snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
117		 "%lu", nr_hugepages_ul);
118
119	slen = strlen(target_nr_hugepages);
120	if (write(fd, target_nr_hugepages, slen) != slen) {
121		ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
122			       nr_hugepages_ul, strerror(errno));
123		goto close_fd;
124	}
125
126	lseek(fd, 0, SEEK_SET);
127
128	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
129		ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
130			       strerror(errno));
131		goto close_fd;
132	}
133
134	/* We should have been able to request at least 1/3 rd of the memory in
135	   huge pages */
136	nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
137	if (!nr_hugepages_ul) {
138		ksft_print_msg("ERROR: No memory is available as huge pages\n");
139		goto close_fd;
140	}
141	compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
142
143	lseek(fd, 0, SEEK_SET);
144
145	if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
146	    != strlen(init_nr_hugepages)) {
147		ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
148			       strerror(errno));
149		goto close_fd;
150	}
151
152	ksft_print_msg("Number of huge pages allocated = %lu\n",
153		       nr_hugepages_ul);
154
155	if (compaction_index > 3) {
156		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
157			       "as huge pages\n", compaction_index);
158		goto close_fd;
159	}
160
161	ret = 0;
162
163 close_fd:
164	close(fd);
165 out:
166	ksft_test_result(ret == 0, "check_compaction\n");
167	return ret;
168}
169
170int set_zero_hugepages(unsigned long *initial_nr_hugepages)
171{
172	int fd, ret = -1;
173	char nr_hugepages[20] = {0};
174
175	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
176	if (fd < 0) {
177		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
178			       strerror(errno));
179		goto out;
180	}
181	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
182		ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
183			       strerror(errno));
184		goto close_fd;
185	}
186
187	lseek(fd, 0, SEEK_SET);
188
189	/* Start with the initial condition of 0 huge pages */
190	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
191		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
192			       strerror(errno));
193		goto close_fd;
194	}
195
196	*initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
197	ret = 0;
198
199 close_fd:
200	close(fd);
201
202 out:
203	return ret;
204}
205
206int main(int argc, char **argv)
207{
208	struct rlimit lim;
209	struct map_list *list = NULL, *entry;
210	size_t page_size, i;
211	void *map = NULL;
212	unsigned long mem_free = 0;
213	unsigned long hugepage_size = 0;
214	long mem_fragmentable_MB = 0;
215	unsigned long initial_nr_hugepages;
216
217	ksft_print_header();
218
219	if (prereq() || geteuid())
220		ksft_exit_skip("Prerequisites unsatisfied\n");
221
222	ksft_set_plan(1);
223
224	/* Start the test without hugepages reducing mem_free */
225	if (set_zero_hugepages(&initial_nr_hugepages))
226		ksft_exit_fail();
227
228	lim.rlim_cur = RLIM_INFINITY;
229	lim.rlim_max = RLIM_INFINITY;
230	if (setrlimit(RLIMIT_MEMLOCK, &lim))
231		ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
232
233	page_size = getpagesize();
234
235	if (read_memory_info(&mem_free, &hugepage_size) != 0)
236		ksft_exit_fail_msg("Failed to get meminfo\n");
237
238	mem_fragmentable_MB = mem_free * 0.8 / 1024;
239
240	while (mem_fragmentable_MB > 0) {
241		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
242			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
243		if (map == MAP_FAILED)
244			break;
245
246		entry = malloc(sizeof(struct map_list));
247		if (!entry) {
248			munmap(map, MAP_SIZE);
249			break;
250		}
251		entry->map = map;
252		entry->next = list;
253		list = entry;
254
255		/* Write something (in this case the address of the map) to
256		 * ensure that KSM can't merge the mapped pages
257		 */
258		for (i = 0; i < MAP_SIZE; i += page_size)
259			*(unsigned long *)(map + i) = (unsigned long)map + i;
260
261		mem_fragmentable_MB -= MAP_SIZE_MB;
262	}
263
264	for (entry = list; entry != NULL; entry = entry->next) {
265		munmap(entry->map, MAP_SIZE);
266		if (!entry->next)
267			break;
268		entry = entry->next;
269	}
270
271	if (check_compaction(mem_free, hugepage_size,
272			     initial_nr_hugepages) == 0)
273		ksft_exit_pass();
274
275	ksft_exit_fail();
276}