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
24 struct map_list {
25 void *map;
26 struct map_list *next;
27 };
28
29 int 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
57 int 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
85 int 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
161 int 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, "", 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
197 int 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 }
268
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.