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 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 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 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[20] = {0}; 93 94 sprintf(init_nr_hugepages, "%lu", initial_nr_hugepages); 95 96 /* We want to test with 80% of available memory. Else, OOM killer comes 97 in to play */ 98 mem_free = mem_free * 0.8; 99 100 fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK); 101 if (fd < 0) { 102 ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n", 103 strerror(errno)); 104 ret = -1; 105 goto out; 106 } 107 108 /* Request a large number of huge pages. The Kernel will allocate 109 as much as it can */ 110 if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) { 111 ksft_print_msg("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n", 112 strerror(errno)); 113 goto close_fd; 114 } 115 116 lseek(fd, 0, SEEK_SET); 117 118 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) { 119 ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n", 120 strerror(errno)); 121 goto close_fd; 122 } 123 124 /* We should have been able to request at least 1/3 rd of the memory in 125 huge pages */ 126 nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10); 127 if (!nr_hugepages_ul) { 128 ksft_print_msg("ERROR: No memory is available as huge pages\n"); 129 goto close_fd; 130 } 131 compaction_index = mem_free/(nr_hugepages_ul * hugepage_size); 132 133 lseek(fd, 0, SEEK_SET); 134 135 if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages)) 136 != strlen(init_nr_hugepages)) { 137 ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n", 138 strerror(errno)); 139 goto close_fd; 140 } 141 142 ksft_print_msg("Number of huge pages allocated = %lu\n", 143 nr_hugepages_ul); 144 145 if (compaction_index > 3) { 146 ksft_print_msg("ERROR: Less than 1/%d of memory is available\n" 147 "as huge pages\n", compaction_index); 148 goto close_fd; 149 } 150 151 ret = 0; 152 153 close_fd: 154 close(fd); 155 out: 156 ksft_test_result(ret == 0, "check_compaction\n"); 157 return ret; 158 } 159 160 int set_zero_hugepages(unsigned long *initial_nr_hugepages) 161 { 162 int fd, ret = -1; 163 char nr_hugepages[20] = {0}; 164 165 fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK); 166 if (fd < 0) { 167 ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n", 168 strerror(errno)); 169 goto out; 170 } 171 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) { 172 ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n", 173 strerror(errno)); 174 goto close_fd; 175 } 176 177 lseek(fd, 0, SEEK_SET); 178 179 /* Start with the initial condition of 0 huge pages */ 180 if (write(fd, "0", sizeof(char)) != sizeof(char)) { 181 ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n", 182 strerror(errno)); 183 goto close_fd; 184 } 185 186 *initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10); 187 ret = 0; 188 189 close_fd: 190 close(fd); 191 192 out: 193 return ret; 194 } 195 196 int main(int argc, char **argv) 197 { 198 struct rlimit lim; 199 struct map_list *list = NULL, *entry; 200 size_t page_size, i; 201 void *map = NULL; 202 unsigned long mem_free = 0; 203 unsigned long hugepage_size = 0; 204 long mem_fragmentable_MB = 0; 205 unsigned long initial_nr_hugepages; 206 207 ksft_print_header(); 208 209 if (prereq() || geteuid()) 210 ksft_exit_skip("Prerequisites unsatisfied\n"); 211 212 ksft_set_plan(1); 213 214 /* Start the test without hugepages reducing mem_free */ 215 if (set_zero_hugepages(&initial_nr_hugepages)) 216 ksft_exit_fail(); 217 218 lim.rlim_cur = RLIM_INFINITY; 219 lim.rlim_max = RLIM_INFINITY; 220 if (setrlimit(RLIMIT_MEMLOCK, &lim)) 221 ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno)); 222 223 page_size = getpagesize(); 224 225 if (read_memory_info(&mem_free, &hugepage_size) != 0) 226 ksft_exit_fail_msg("Failed to get meminfo\n"); 227 228 mem_fragmentable_MB = mem_free * 0.8 / 1024; 229 230 while (mem_fragmentable_MB > 0) { 231 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, 232 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0); 233 if (map == MAP_FAILED) 234 break; 235 236 entry = malloc(sizeof(struct map_list)); 237 if (!entry) { 238 munmap(map, MAP_SIZE); 239 break; 240 } 241 entry->map = map; 242 entry->next = list; 243 list = entry; 244 245 /* Write something (in this case the address of the map) to 246 * ensure that KSM can't merge the mapped pages 247 */ 248 for (i = 0; i < MAP_SIZE; i += page_size) 249 *(unsigned long *)(map + i) = (unsigned long)map + i; 250 251 mem_fragmentable_MB -= MAP_SIZE_MB; 252 } 253 254 for (entry = list; entry != NULL; entry = entry->next) { 255 munmap(entry->map, MAP_SIZE); 256 if (!entry->next) 257 break; 258 entry = entry->next; 259 } 260 261 if (check_compaction(mem_free, hugepage_size, 262 initial_nr_hugepages) == 0) 263 ksft_exit_pass(); 264 265 ksft_exit_fail(); 266 } 267