tools/testing/selftests/mm/compaction_test.c

   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[24] = {0};
  93
  94         snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
  95                  "%lu", initial_nr_hugepages);
  96
  97         /* We want to test with 80% of available memory. Else, OOM killer comes
  98            in to play */
  99         mem_free = mem_free * 0.8;
 100
 101         fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
 102         if (fd < 0) {
 103                 ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
 104                                strerror(errno));
 105                 ret = -1;
 106                 goto out;
 107         }
 108
 109         /* Request a large number of huge pages. The Kernel will allocate
 110            as much as it can */
 111         if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
 112                 ksft_print_msg("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
 113                                strerror(errno));
 114                 goto close_fd;
 115         }
 116
 117         lseek(fd, 0, SEEK_SET);
 118
 119         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
 120                 ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
 121                                strerror(errno));
 122                 goto close_fd;
 123         }
 124
 125         /* We should have been able to request at least 1/3 rd of the memory in
 126            huge pages */
 127         nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
 128         if (!nr_hugepages_ul) {
 129                 ksft_print_msg("ERROR: No memory is available as huge pages\n");
 130                 goto close_fd;
 131         }
 132         compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
 133
 134         lseek(fd, 0, SEEK_SET);
 135
 136         if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
 137             != strlen(init_nr_hugepages)) {
 138                 ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
 139                                strerror(errno));
 140                 goto close_fd;
 141         }
 142
 143         ksft_print_msg("Number of huge pages allocated = %lu\n",
 144                        nr_hugepages_ul);
 145
 146         if (compaction_index > 3) {
 147                 ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
 148                                "as huge pages\n", compaction_index);
 149                 goto close_fd;
 150         }
 151
 152         ret = 0;
 153
 154  close_fd:
 155         close(fd);
 156  out:
 157         ksft_test_result(ret == 0, "check_compaction\n");
 158         return ret;
 159 }
 160
 161 int set_zero_hugepages(unsigned long *initial_nr_hugepages)
 162 {
 163         int fd, ret = -1;
 164         char nr_hugepages[20] = {0};
 165
 166         fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
 167         if (fd < 0) {
 168                 ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
 169                                strerror(errno));
 170                 goto out;
 171         }
 172         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
 173                 ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
 174                                strerror(errno));
 175                 goto close_fd;
 176         }
 177
 178         lseek(fd, 0, SEEK_SET);
 179
 180         /* Start with the initial condition of 0 huge pages */
 181         if (write(fd, "0", sizeof(char)) != sizeof(char)) {
 182                 ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
 183                                strerror(errno));
 184                 goto close_fd;
 185         }
 186
 187         *initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
 188         ret = 0;
 189
 190  close_fd:
 191         close(fd);
 192
 193  out:
 194         return ret;
 195 }
 196
 197 int main(int argc, char **argv)
 198 {
 199         struct rlimit lim;
 200         struct map_list *list = NULL, *entry;
 201         size_t page_size, i;
 202         void *map = NULL;
 203         unsigned long mem_free = 0;
 204         unsigned long hugepage_size = 0;
 205         long mem_fragmentable_MB = 0;
 206         unsigned long initial_nr_hugepages;
 207
 208         ksft_print_header();
 209
 210         if (prereq() || geteuid())
 211                 ksft_exit_skip("Prerequisites unsatisfied\n");
 212
 213         ksft_set_plan(1);
 214
 215         /* Start the test without hugepages reducing mem_free */
 216         if (set_zero_hugepages(&initial_nr_hugepages))
 217                 ksft_exit_fail();
 218
 219         lim.rlim_cur = RLIM_INFINITY;
 220         lim.rlim_max = RLIM_INFINITY;
 221         if (setrlimit(RLIMIT_MEMLOCK, &lim))
 222                 ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
 223
 224         page_size = getpagesize();
 225
 226         if (read_memory_info(&mem_free, &hugepage_size) != 0)
 227                 ksft_exit_fail_msg("Failed to get meminfo\n");
 228
 229         mem_fragmentable_MB = mem_free * 0.8 / 1024;
 230
 231         while (mem_fragmentable_MB > 0) {
 232                 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 233                            MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 234                 if (map == MAP_FAILED)
 235                         break;
 236
 237                 entry = malloc(sizeof(struct map_list));
 238                 if (!entry) {
 239                         munmap(map, MAP_SIZE);
 240                         break;
 241                 }
 242                 entry->map = map;
 243                 entry->next = list;
 244                 list = entry;
 245
 246                 /* Write something (in this case the address of the map) to
 247                  * ensure that KSM can't merge the mapped pages
 248                  */
 249                 for (i = 0; i < MAP_SIZE; i += page_size)
 250                         *(unsigned long *)(map + i) = (unsigned long)map + i;
 251
 252                 mem_fragmentable_MB -= MAP_SIZE_MB;
 253         }
 254
 255         for (entry = list; entry != NULL; entry = entry->next) {
 256                 munmap(entry->map, MAP_SIZE);
 257                 if (!entry->next)
 258                         break;
 259                 entry = entry->next;
 260         }
 261
 262         if (check_compaction(mem_free, hugepage_size,
 263                              initial_nr_hugepages) == 0)
 264                 ksft_exit_pass();
 265
 266         ksft_exit_fail();
 267 }