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)85 int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
86 {
87 unsigned long nr_hugepages_ul;
88 int fd, ret = -1;
89 int compaction_index = 0;
90 char initial_nr_hugepages[20] = {0};
91 char nr_hugepages[20] = {0};
92 char target_nr_hugepages[24] = {0};
93 int slen;
94
95 /* We want to test with 80% of available memory. Else, OOM killer comes
96 in to play */
97 mem_free = mem_free * 0.8;
98
99 fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
100 if (fd < 0) {
101 ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
102 strerror(errno));
103 ret = -1;
104 goto out;
105 }
106
107 if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
108 ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
109 strerror(errno));
110 goto close_fd;
111 }
112
113 lseek(fd, 0, SEEK_SET);
114
115 /* Start with the initial condition of 0 huge pages*/
116 if (write(fd, "0", sizeof(char)) != sizeof(char)) {
117 ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
118 strerror(errno));
119 goto close_fd;
120 }
121
122 lseek(fd, 0, SEEK_SET);
123
124 /*
125 * Request huge pages for about half of the free memory. The Kernel
126 * will allocate as much as it can, and we expect it will get at least 1/3
127 */
128 nr_hugepages_ul = mem_free / hugepage_size / 2;
129 snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
130 "%lu", nr_hugepages_ul);
131
132 slen = strlen(target_nr_hugepages);
133 if (write(fd, target_nr_hugepages, slen) != slen) {
134 ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
135 nr_hugepages_ul, strerror(errno));
136 goto close_fd;
137 }
138
139 lseek(fd, 0, SEEK_SET);
140
141 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
142 ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
143 strerror(errno));
144 goto close_fd;
145 }
146
147 /* We should have been able to request at least 1/3 rd of the memory in
148 huge pages */
149 nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
150 if (!nr_hugepages_ul) {
151 ksft_print_msg("ERROR: No memory is available as huge pages\n");
152 goto close_fd;
153 }
154 compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
155
156 lseek(fd, 0, SEEK_SET);
157
158 if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
159 != strlen(initial_nr_hugepages)) {
160 ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
161 strerror(errno));
162 goto close_fd;
163 }
164
165 ksft_print_msg("Number of huge pages allocated = %lu\n",
166 nr_hugepages_ul);
167
168 if (compaction_index > 3) {
169 ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
170 "as huge pages\n", compaction_index);
171 goto close_fd;
172 }
173
174 ret = 0;
175
176 close_fd:
177 close(fd);
178 out:
179 ksft_test_result(ret == 0, "check_compaction\n");
180 return ret;
181 }
182
183
main(int argc,char ** argv)184 int main(int argc, char **argv)
185 {
186 struct rlimit lim;
187 struct map_list *list = NULL, *entry;
188 size_t page_size, i;
189 void *map = NULL;
190 unsigned long mem_free = 0;
191 unsigned long hugepage_size = 0;
192 long mem_fragmentable_MB = 0;
193
194 ksft_print_header();
195
196 if (prereq() != 0)
197 return ksft_exit_pass();
198
199 ksft_set_plan(1);
200
201 lim.rlim_cur = RLIM_INFINITY;
202 lim.rlim_max = RLIM_INFINITY;
203 if (setrlimit(RLIMIT_MEMLOCK, &lim))
204 ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
205
206 page_size = getpagesize();
207
208 if (read_memory_info(&mem_free, &hugepage_size) != 0)
209 ksft_exit_fail_msg("Failed to get meminfo\n");
210
211 mem_fragmentable_MB = mem_free * 0.8 / 1024;
212
213 while (mem_fragmentable_MB > 0) {
214 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
215 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
216 if (map == MAP_FAILED)
217 break;
218
219 entry = malloc(sizeof(struct map_list));
220 if (!entry) {
221 munmap(map, MAP_SIZE);
222 break;
223 }
224 entry->map = map;
225 entry->next = list;
226 list = entry;
227
228 /* Write something (in this case the address of the map) to
229 * ensure that KSM can't merge the mapped pages
230 */
231 for (i = 0; i < MAP_SIZE; i += page_size)
232 *(unsigned long *)(map + i) = (unsigned long)map + i;
233
234 mem_fragmentable_MB -= MAP_SIZE_MB;
235 }
236
237 for (entry = list; entry != NULL; entry = entry->next) {
238 munmap(entry->map, MAP_SIZE);
239 if (!entry->next)
240 break;
241 entry = entry->next;
242 }
243
244 if (check_compaction(mem_free, hugepage_size) == 0)
245 return ksft_exit_pass();
246
247 return ksft_exit_fail();
248 }
249