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
read_memory_info(unsigned long * memfree,unsigned long * hugepagesize)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
prereq(void)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
check_compaction(unsigned long mem_free,unsigned long hugepage_size,unsigned long initial_nr_hugepages)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 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
set_zero_hugepages(unsigned long * initial_nr_hugepages)170 int 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
main(int argc,char ** argv)206 int 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 }
277