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		perror("Failed to read meminfo\n");
 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		perror("Failed to read meminfo\n");
 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		perror("Failed to open\n"
 66		       "/proc/sys/vm/compact_unevictable_allowed\n");
 67		return -1;
 68	}
 69
 70	if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
 71		perror("Failed to read from\n"
 72		       "/proc/sys/vm/compact_unevictable_allowed\n");
 73		close(fd);
 74		return -1;
 75	}
 76
 77	close(fd);
 78	if (allowed == '1')
 79		return 0;
 80
 81	return -1;
 82}
 83
 84int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 85{
 86	int fd;
 87	int compaction_index = 0;
 88	char initial_nr_hugepages[10] = {0};
 89	char nr_hugepages[10] = {0};
 90
 91	/* We want to test with 80% of available memory. Else, OOM killer comes
 92	   in to play */
 93	mem_free = mem_free * 0.8;
 94
 95	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
 96	if (fd < 0) {
 97		perror("Failed to open /proc/sys/vm/nr_hugepages");
 98		return -1;
 99	}
100
101	if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
102		perror("Failed to read from /proc/sys/vm/nr_hugepages");
103		goto close_fd;
104	}
105
106	/* Start with the initial condition of 0 huge pages*/
107	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
108		perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
109		goto close_fd;
110	}
111
112	lseek(fd, 0, SEEK_SET);
113
114	/* Request a large number of huge pages. The Kernel will allocate
115	   as much as it can */
116	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
117		perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
118		goto close_fd;
119	}
120
121	lseek(fd, 0, SEEK_SET);
122
123	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
124		perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
125		goto close_fd;
126	}
127
128	/* We should have been able to request at least 1/3 rd of the memory in
129	   huge pages */
130	compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
131
132	if (compaction_index > 3) {
133		printf("No of huge pages allocated = %d\n",
134		       (atoi(nr_hugepages)));
135		fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
136			"as huge pages\n", compaction_index);
137		goto close_fd;
138	}
139
140	printf("No of huge pages allocated = %d\n",
141	       (atoi(nr_hugepages)));
142
143	lseek(fd, 0, SEEK_SET);
144
145	if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
146	    != strlen(initial_nr_hugepages)) {
147		perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
148		goto close_fd;
149	}
150
151	close(fd);
152	return 0;
153
154 close_fd:
155	close(fd);
156	printf("Not OK. Compaction test failed.");
157	return -1;
158}
159
160
161int main(int argc, char **argv)
162{
163	struct rlimit lim;
164	struct map_list *list, *entry;
165	size_t page_size, i;
166	void *map = NULL;
167	unsigned long mem_free = 0;
168	unsigned long hugepage_size = 0;
169	long mem_fragmentable_MB = 0;
170
171	if (prereq() != 0) {
172		printf("Either the sysctl compact_unevictable_allowed is not\n"
173		       "set to 1 or couldn't read the proc file.\n"
174		       "Skipping the test\n");
175		return KSFT_SKIP;
176	}
177
178	lim.rlim_cur = RLIM_INFINITY;
179	lim.rlim_max = RLIM_INFINITY;
180	if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
181		perror("Failed to set rlimit:\n");
182		return -1;
183	}
184
185	page_size = getpagesize();
186
187	list = NULL;
188
189	if (read_memory_info(&mem_free, &hugepage_size) != 0) {
190		printf("ERROR: Cannot read meminfo\n");
191		return -1;
192	}
193
194	mem_fragmentable_MB = mem_free * 0.8 / 1024;
195
196	while (mem_fragmentable_MB > 0) {
197		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
198			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
199		if (map == MAP_FAILED)
200			break;
201
202		entry = malloc(sizeof(struct map_list));
203		if (!entry) {
204			munmap(map, MAP_SIZE);
205			break;
206		}
207		entry->map = map;
208		entry->next = list;
209		list = entry;
210
211		/* Write something (in this case the address of the map) to
212		 * ensure that KSM can't merge the mapped pages
213		 */
214		for (i = 0; i < MAP_SIZE; i += page_size)
215			*(unsigned long *)(map + i) = (unsigned long)map + i;
216
217		mem_fragmentable_MB -= MAP_SIZE_MB;
218	}
219
220	for (entry = list; entry != NULL; entry = entry->next) {
221		munmap(entry->map, MAP_SIZE);
222		if (!entry->next)
223			break;
224		entry = entry->next;
225	}
226
227	if (check_compaction(mem_free, hugepage_size) == 0)
228		return 0;
229
230	return -1;
231}