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 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
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 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
check_compaction(unsigned long mem_free,unsigned int hugepage_size)84 int 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
main(int argc,char ** argv)161 int 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 }
232