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 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 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 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 lseek(fd, 0, SEEK_SET); 107 108 /* Start with the initial condition of 0 huge pages*/ 109 if (write(fd, "0", sizeof(char)) != sizeof(char)) { 110 perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n"); 111 goto close_fd; 112 } 113 114 lseek(fd, 0, SEEK_SET); 115 116 /* Request a large number of huge pages. The Kernel will allocate 117 as much as it can */ 118 if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) { 119 perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n"); 120 goto close_fd; 121 } 122 123 lseek(fd, 0, SEEK_SET); 124 125 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) { 126 perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n"); 127 goto close_fd; 128 } 129 130 /* We should have been able to request at least 1/3 rd of the memory in 131 huge pages */ 132 compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size); 133 134 if (compaction_index > 3) { 135 printf("No of huge pages allocated = %d\n", 136 (atoi(nr_hugepages))); 137 fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n" 138 "as huge pages\n", compaction_index); 139 goto close_fd; 140 } 141 142 printf("No of huge pages allocated = %d\n", 143 (atoi(nr_hugepages))); 144 145 lseek(fd, 0, SEEK_SET); 146 147 if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages)) 148 != strlen(initial_nr_hugepages)) { 149 perror("Failed to write value to /proc/sys/vm/nr_hugepages\n"); 150 goto close_fd; 151 } 152 153 close(fd); 154 return 0; 155 156 close_fd: 157 close(fd); 158 printf("Not OK. Compaction test failed."); 159 return -1; 160 } 161 162 163 int main(int argc, char **argv) 164 { 165 struct rlimit lim; 166 struct map_list *list, *entry; 167 size_t page_size, i; 168 void *map = NULL; 169 unsigned long mem_free = 0; 170 unsigned long hugepage_size = 0; 171 long mem_fragmentable_MB = 0; 172 173 if (prereq() != 0) { 174 printf("Either the sysctl compact_unevictable_allowed is not\n" 175 "set to 1 or couldn't read the proc file.\n" 176 "Skipping the test\n"); 177 return KSFT_SKIP; 178 } 179 180 lim.rlim_cur = RLIM_INFINITY; 181 lim.rlim_max = RLIM_INFINITY; 182 if (setrlimit(RLIMIT_MEMLOCK, &lim)) { 183 perror("Failed to set rlimit:\n"); 184 return -1; 185 } 186 187 page_size = getpagesize(); 188 189 list = NULL; 190 191 if (read_memory_info(&mem_free, &hugepage_size) != 0) { 192 printf("ERROR: Cannot read meminfo\n"); 193 return -1; 194 } 195 196 mem_fragmentable_MB = mem_free * 0.8 / 1024; 197 198 while (mem_fragmentable_MB > 0) { 199 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, 200 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0); 201 if (map == MAP_FAILED) 202 break; 203 204 entry = malloc(sizeof(struct map_list)); 205 if (!entry) { 206 munmap(map, MAP_SIZE); 207 break; 208 } 209 entry->map = map; 210 entry->next = list; 211 list = entry; 212 213 /* Write something (in this case the address of the map) to 214 * ensure that KSM can't merge the mapped pages 215 */ 216 for (i = 0; i < MAP_SIZE; i += page_size) 217 *(unsigned long *)(map + i) = (unsigned long)map + i; 218 219 mem_fragmentable_MB -= MAP_SIZE_MB; 220 } 221 222 for (entry = list; entry != NULL; entry = entry->next) { 223 munmap(entry->map, MAP_SIZE); 224 if (!entry->next) 225 break; 226 entry = entry->next; 227 } 228 229 if (check_compaction(mem_free, hugepage_size) == 0) 230 return 0; 231 232 return -1; 233 } 234