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 1048576
22
23 struct map_list {
24 void *map;
25 struct map_list *next;
26 };
27
read_memory_info(unsigned long * memfree,unsigned long * hugepagesize)28 int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
29 {
30 char buffer[256] = {0};
31 char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
32 FILE *cmdfile = popen(cmd, "r");
33
34 if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
35 perror("Failed to read meminfo\n");
36 return -1;
37 }
38
39 pclose(cmdfile);
40
41 *memfree = atoll(buffer);
42 cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
43 cmdfile = popen(cmd, "r");
44
45 if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
46 perror("Failed to read meminfo\n");
47 return -1;
48 }
49
50 pclose(cmdfile);
51 *hugepagesize = atoll(buffer);
52
53 return 0;
54 }
55
prereq(void)56 int prereq(void)
57 {
58 char allowed;
59 int fd;
60
61 fd = open("/proc/sys/vm/compact_unevictable_allowed",
62 O_RDONLY | O_NONBLOCK);
63 if (fd < 0) {
64 perror("Failed to open\n"
65 "/proc/sys/vm/compact_unevictable_allowed\n");
66 return -1;
67 }
68
69 if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
70 perror("Failed to read from\n"
71 "/proc/sys/vm/compact_unevictable_allowed\n");
72 close(fd);
73 return -1;
74 }
75
76 close(fd);
77 if (allowed == '1')
78 return 0;
79
80 return -1;
81 }
82
check_compaction(unsigned long mem_free,unsigned int hugepage_size)83 int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
84 {
85 int fd;
86 int compaction_index = 0;
87 char initial_nr_hugepages[10] = {0};
88 char nr_hugepages[10] = {0};
89
90 /* We want to test with 80% of available memory. Else, OOM killer comes
91 in to play */
92 mem_free = mem_free * 0.8;
93
94 fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
95 if (fd < 0) {
96 perror("Failed to open /proc/sys/vm/nr_hugepages");
97 return -1;
98 }
99
100 if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
101 perror("Failed to read from /proc/sys/vm/nr_hugepages");
102 goto close_fd;
103 }
104
105 /* Start with the initial condition of 0 huge pages*/
106 if (write(fd, "0", sizeof(char)) != sizeof(char)) {
107 perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
108 goto close_fd;
109 }
110
111 lseek(fd, 0, SEEK_SET);
112
113 /* Request a large number of huge pages. The Kernel will allocate
114 as much as it can */
115 if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
116 perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
117 goto close_fd;
118 }
119
120 lseek(fd, 0, SEEK_SET);
121
122 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
123 perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
124 goto close_fd;
125 }
126
127 /* We should have been able to request at least 1/3 rd of the memory in
128 huge pages */
129 compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
130
131 if (compaction_index > 3) {
132 printf("No of huge pages allocated = %d\n",
133 (atoi(nr_hugepages)));
134 fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
135 "as huge pages\n", compaction_index);
136 goto close_fd;
137 }
138
139 printf("No of huge pages allocated = %d\n",
140 (atoi(nr_hugepages)));
141
142 lseek(fd, 0, SEEK_SET);
143
144 if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
145 != strlen(initial_nr_hugepages)) {
146 perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
147 goto close_fd;
148 }
149
150 close(fd);
151 return 0;
152
153 close_fd:
154 close(fd);
155 printf("Not OK. Compaction test failed.");
156 return -1;
157 }
158
159
main(int argc,char ** argv)160 int main(int argc, char **argv)
161 {
162 struct rlimit lim;
163 struct map_list *list, *entry;
164 size_t page_size, i;
165 void *map = NULL;
166 unsigned long mem_free = 0;
167 unsigned long hugepage_size = 0;
168 unsigned long mem_fragmentable = 0;
169
170 if (prereq() != 0) {
171 printf("Either the sysctl compact_unevictable_allowed is not\n"
172 "set to 1 or couldn't read the proc file.\n"
173 "Skipping the test\n");
174 return KSFT_SKIP;
175 }
176
177 lim.rlim_cur = RLIM_INFINITY;
178 lim.rlim_max = RLIM_INFINITY;
179 if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
180 perror("Failed to set rlimit:\n");
181 return -1;
182 }
183
184 page_size = getpagesize();
185
186 list = NULL;
187
188 if (read_memory_info(&mem_free, &hugepage_size) != 0) {
189 printf("ERROR: Cannot read meminfo\n");
190 return -1;
191 }
192
193 mem_fragmentable = mem_free * 0.8 / 1024;
194
195 while (mem_fragmentable > 0) {
196 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
197 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
198 if (map == MAP_FAILED)
199 break;
200
201 entry = malloc(sizeof(struct map_list));
202 if (!entry) {
203 munmap(map, MAP_SIZE);
204 break;
205 }
206 entry->map = map;
207 entry->next = list;
208 list = entry;
209
210 /* Write something (in this case the address of the map) to
211 * ensure that KSM can't merge the mapped pages
212 */
213 for (i = 0; i < MAP_SIZE; i += page_size)
214 *(unsigned long *)(map + i) = (unsigned long)map + i;
215
216 mem_fragmentable--;
217 }
218
219 for (entry = list; entry != NULL; entry = entry->next) {
220 munmap(entry->map, MAP_SIZE);
221 if (!entry->next)
222 break;
223 entry = entry->next;
224 }
225
226 if (check_compaction(mem_free, hugepage_size) == 0)
227 return 0;
228
229 return -1;
230 }
231