1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Stress userfaultfd syscall. 4 * 5 * Copyright (C) 2015 Red Hat, Inc. 6 * 7 * This test allocates two virtual areas and bounces the physical 8 * memory across the two virtual areas (from area_src to area_dst) 9 * using userfaultfd. 10 * 11 * There are three threads running per CPU: 12 * 13 * 1) one per-CPU thread takes a per-page pthread_mutex in a random 14 * page of the area_dst (while the physical page may still be in 15 * area_src), and increments a per-page counter in the same page, 16 * and checks its value against a verification region. 17 * 18 * 2) another per-CPU thread handles the userfaults generated by 19 * thread 1 above. userfaultfd blocking reads or poll() modes are 20 * exercised interleaved. 21 * 22 * 3) one last per-CPU thread transfers the memory in the background 23 * at maximum bandwidth (if not already transferred by thread 24 * 2). Each cpu thread takes cares of transferring a portion of the 25 * area. 26 * 27 * When all threads of type 3 completed the transfer, one bounce is 28 * complete. area_src and area_dst are then swapped. All threads are 29 * respawned and so the bounce is immediately restarted in the 30 * opposite direction. 31 * 32 * per-CPU threads 1 by triggering userfaults inside 33 * pthread_mutex_lock will also verify the atomicity of the memory 34 * transfer (UFFDIO_COPY). 35 */ 36 #include <asm-generic/unistd.h> 37 #include "uffd-common.h" 38 39 uint64_t features; 40 41 #define BOUNCE_RANDOM (1<<0) 42 #define BOUNCE_RACINGFAULTS (1<<1) 43 #define BOUNCE_VERIFY (1<<2) 44 #define BOUNCE_POLL (1<<3) 45 static int bounces; 46 47 /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */ 48 #define ALARM_INTERVAL_SECS 10 49 static char *zeropage; 50 pthread_attr_t attr; 51 52 #define swap(a, b) \ 53 do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) 54 55 const char *examples = 56 "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" 57 "./uffd-stress anon 100 99999\n\n" 58 "# Run share memory test on 1GiB region with 99 bounces:\n" 59 "./uffd-stress shmem 1000 99\n\n" 60 "# Run hugetlb memory test on 256MiB region with 50 bounces:\n" 61 "./uffd-stress hugetlb 256 50\n\n" 62 "# Run the same hugetlb test but using private file:\n" 63 "./uffd-stress hugetlb-private 256 50\n\n" 64 "# 10MiB-~6GiB 999 bounces anonymous test, " 65 "continue forever unless an error triggers\n" 66 "while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n"; 67 68 static void usage(void) 69 { 70 fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n"); 71 fprintf(stderr, "Supported <test type>: anon, hugetlb, " 72 "hugetlb-private, shmem, shmem-private\n\n"); 73 fprintf(stderr, "Examples:\n\n"); 74 fprintf(stderr, "%s", examples); 75 exit(1); 76 } 77 78 static void uffd_stats_reset(struct uffd_args *args, unsigned long n_cpus) 79 { 80 int i; 81 82 for (i = 0; i < n_cpus; i++) { 83 args[i].cpu = i; 84 args[i].apply_wp = test_uffdio_wp; 85 args[i].missing_faults = 0; 86 args[i].wp_faults = 0; 87 args[i].minor_faults = 0; 88 } 89 } 90 91 static void *locking_thread(void *arg) 92 { 93 unsigned long cpu = (unsigned long) arg; 94 unsigned long page_nr; 95 unsigned long long count; 96 97 if (!(bounces & BOUNCE_RANDOM)) { 98 page_nr = -bounces; 99 if (!(bounces & BOUNCE_RACINGFAULTS)) 100 page_nr += cpu * nr_pages_per_cpu; 101 } 102 103 while (!finished) { 104 if (bounces & BOUNCE_RANDOM) { 105 if (getrandom(&page_nr, sizeof(page_nr), 0) != sizeof(page_nr)) 106 err("getrandom failed"); 107 } else 108 page_nr += 1; 109 page_nr %= nr_pages; 110 pthread_mutex_lock(area_mutex(area_dst, page_nr)); 111 count = *area_count(area_dst, page_nr); 112 if (count != count_verify[page_nr]) 113 err("page_nr %lu memory corruption %llu %llu", 114 page_nr, count, count_verify[page_nr]); 115 count++; 116 *area_count(area_dst, page_nr) = count_verify[page_nr] = count; 117 pthread_mutex_unlock(area_mutex(area_dst, page_nr)); 118 } 119 120 return NULL; 121 } 122 123 static int copy_page_retry(int ufd, unsigned long offset) 124 { 125 return __copy_page(ufd, offset, true, test_uffdio_wp); 126 } 127 128 pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER; 129 130 static void *uffd_read_thread(void *arg) 131 { 132 struct uffd_args *args = (struct uffd_args *)arg; 133 struct uffd_msg msg; 134 135 pthread_mutex_unlock(&uffd_read_mutex); 136 /* from here cancellation is ok */ 137 138 for (;;) { 139 if (uffd_read_msg(uffd, &msg)) 140 continue; 141 uffd_handle_page_fault(&msg, args); 142 } 143 144 return NULL; 145 } 146 147 static void *background_thread(void *arg) 148 { 149 unsigned long cpu = (unsigned long) arg; 150 unsigned long page_nr, start_nr, mid_nr, end_nr; 151 152 start_nr = cpu * nr_pages_per_cpu; 153 end_nr = (cpu+1) * nr_pages_per_cpu; 154 mid_nr = (start_nr + end_nr) / 2; 155 156 /* Copy the first half of the pages */ 157 for (page_nr = start_nr; page_nr < mid_nr; page_nr++) 158 copy_page_retry(uffd, page_nr * page_size); 159 160 /* 161 * If we need to test uffd-wp, set it up now. Then we'll have 162 * at least the first half of the pages mapped already which 163 * can be write-protected for testing 164 */ 165 if (test_uffdio_wp) 166 wp_range(uffd, (unsigned long)area_dst + start_nr * page_size, 167 nr_pages_per_cpu * page_size, true); 168 169 /* 170 * Continue the 2nd half of the page copying, handling write 171 * protection faults if any 172 */ 173 for (page_nr = mid_nr; page_nr < end_nr; page_nr++) 174 copy_page_retry(uffd, page_nr * page_size); 175 176 return NULL; 177 } 178 179 static int stress(struct uffd_args *args) 180 { 181 unsigned long cpu; 182 pthread_t locking_threads[nr_cpus]; 183 pthread_t uffd_threads[nr_cpus]; 184 pthread_t background_threads[nr_cpus]; 185 186 finished = 0; 187 for (cpu = 0; cpu < nr_cpus; cpu++) { 188 if (pthread_create(&locking_threads[cpu], &attr, 189 locking_thread, (void *)cpu)) 190 return 1; 191 if (bounces & BOUNCE_POLL) { 192 if (pthread_create(&uffd_threads[cpu], &attr, uffd_poll_thread, &args[cpu])) 193 err("uffd_poll_thread create"); 194 } else { 195 if (pthread_create(&uffd_threads[cpu], &attr, 196 uffd_read_thread, 197 (void *)&args[cpu])) 198 return 1; 199 pthread_mutex_lock(&uffd_read_mutex); 200 } 201 if (pthread_create(&background_threads[cpu], &attr, 202 background_thread, (void *)cpu)) 203 return 1; 204 } 205 for (cpu = 0; cpu < nr_cpus; cpu++) 206 if (pthread_join(background_threads[cpu], NULL)) 207 return 1; 208 209 /* 210 * Be strict and immediately zap area_src, the whole area has 211 * been transferred already by the background treads. The 212 * area_src could then be faulted in a racy way by still 213 * running uffdio_threads reading zeropages after we zapped 214 * area_src (but they're guaranteed to get -EEXIST from 215 * UFFDIO_COPY without writing zero pages into area_dst 216 * because the background threads already completed). 217 */ 218 uffd_test_ops->release_pages(area_src); 219 220 finished = 1; 221 for (cpu = 0; cpu < nr_cpus; cpu++) 222 if (pthread_join(locking_threads[cpu], NULL)) 223 return 1; 224 225 for (cpu = 0; cpu < nr_cpus; cpu++) { 226 char c; 227 if (bounces & BOUNCE_POLL) { 228 if (write(pipefd[cpu*2+1], &c, 1) != 1) 229 err("pipefd write error"); 230 if (pthread_join(uffd_threads[cpu], 231 (void *)&args[cpu])) 232 return 1; 233 } else { 234 if (pthread_cancel(uffd_threads[cpu])) 235 return 1; 236 if (pthread_join(uffd_threads[cpu], NULL)) 237 return 1; 238 } 239 } 240 241 return 0; 242 } 243 244 static int userfaultfd_stress(void) 245 { 246 void *area; 247 unsigned long nr; 248 struct uffd_args args[nr_cpus]; 249 uint64_t mem_size = nr_pages * page_size; 250 int flags = 0; 251 252 memset(args, 0, sizeof(struct uffd_args) * nr_cpus); 253 254 if (features & UFFD_FEATURE_WP_UNPOPULATED && test_type == TEST_ANON) 255 flags = UFFD_FEATURE_WP_UNPOPULATED; 256 257 if (uffd_test_ctx_init(flags, NULL)) 258 err("context init failed"); 259 260 if (posix_memalign(&area, page_size, page_size)) 261 err("out of memory"); 262 zeropage = area; 263 bzero(zeropage, page_size); 264 265 pthread_mutex_lock(&uffd_read_mutex); 266 267 pthread_attr_init(&attr); 268 pthread_attr_setstacksize(&attr, 16*1024*1024); 269 270 while (bounces--) { 271 printf("bounces: %d, mode:", bounces); 272 if (bounces & BOUNCE_RANDOM) 273 printf(" rnd"); 274 if (bounces & BOUNCE_RACINGFAULTS) 275 printf(" racing"); 276 if (bounces & BOUNCE_VERIFY) 277 printf(" ver"); 278 if (bounces & BOUNCE_POLL) 279 printf(" poll"); 280 else 281 printf(" read"); 282 printf(", "); 283 fflush(stdout); 284 285 if (bounces & BOUNCE_POLL) 286 fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); 287 else 288 fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK); 289 290 /* register */ 291 if (uffd_register(uffd, area_dst, mem_size, 292 true, test_uffdio_wp, false)) 293 err("register failure"); 294 295 if (area_dst_alias) { 296 if (uffd_register(uffd, area_dst_alias, mem_size, 297 true, test_uffdio_wp, false)) 298 err("register failure alias"); 299 } 300 301 /* 302 * The madvise done previously isn't enough: some 303 * uffd_thread could have read userfaults (one of 304 * those already resolved by the background thread) 305 * and it may be in the process of calling 306 * UFFDIO_COPY. UFFDIO_COPY will read the zapped 307 * area_src and it would map a zero page in it (of 308 * course such a UFFDIO_COPY is perfectly safe as it'd 309 * return -EEXIST). The problem comes at the next 310 * bounce though: that racing UFFDIO_COPY would 311 * generate zeropages in the area_src, so invalidating 312 * the previous MADV_DONTNEED. Without this additional 313 * MADV_DONTNEED those zeropages leftovers in the 314 * area_src would lead to -EEXIST failure during the 315 * next bounce, effectively leaving a zeropage in the 316 * area_dst. 317 * 318 * Try to comment this out madvise to see the memory 319 * corruption being caught pretty quick. 320 * 321 * khugepaged is also inhibited to collapse THP after 322 * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's 323 * required to MADV_DONTNEED here. 324 */ 325 uffd_test_ops->release_pages(area_dst); 326 327 uffd_stats_reset(args, nr_cpus); 328 329 /* bounce pass */ 330 if (stress(args)) { 331 uffd_test_ctx_clear(); 332 return 1; 333 } 334 335 /* Clear all the write protections if there is any */ 336 if (test_uffdio_wp) 337 wp_range(uffd, (unsigned long)area_dst, 338 nr_pages * page_size, false); 339 340 /* unregister */ 341 if (uffd_unregister(uffd, area_dst, mem_size)) 342 err("unregister failure"); 343 if (area_dst_alias) { 344 if (uffd_unregister(uffd, area_dst_alias, mem_size)) 345 err("unregister failure alias"); 346 } 347 348 /* verification */ 349 if (bounces & BOUNCE_VERIFY) 350 for (nr = 0; nr < nr_pages; nr++) 351 if (*area_count(area_dst, nr) != count_verify[nr]) 352 err("error area_count %llu %llu %lu\n", 353 *area_count(area_src, nr), 354 count_verify[nr], nr); 355 356 /* prepare next bounce */ 357 swap(area_src, area_dst); 358 359 swap(area_src_alias, area_dst_alias); 360 361 uffd_stats_report(args, nr_cpus); 362 } 363 uffd_test_ctx_clear(); 364 365 return 0; 366 } 367 368 static void set_test_type(const char *type) 369 { 370 if (!strcmp(type, "anon")) { 371 test_type = TEST_ANON; 372 uffd_test_ops = &anon_uffd_test_ops; 373 } else if (!strcmp(type, "hugetlb")) { 374 test_type = TEST_HUGETLB; 375 uffd_test_ops = &hugetlb_uffd_test_ops; 376 map_shared = true; 377 } else if (!strcmp(type, "hugetlb-private")) { 378 test_type = TEST_HUGETLB; 379 uffd_test_ops = &hugetlb_uffd_test_ops; 380 } else if (!strcmp(type, "shmem")) { 381 map_shared = true; 382 test_type = TEST_SHMEM; 383 uffd_test_ops = &shmem_uffd_test_ops; 384 } else if (!strcmp(type, "shmem-private")) { 385 test_type = TEST_SHMEM; 386 uffd_test_ops = &shmem_uffd_test_ops; 387 } 388 } 389 390 static void parse_test_type_arg(const char *raw_type) 391 { 392 set_test_type(raw_type); 393 394 if (!test_type) 395 err("failed to parse test type argument: '%s'", raw_type); 396 397 if (test_type == TEST_HUGETLB) 398 page_size = default_huge_page_size(); 399 else 400 page_size = sysconf(_SC_PAGE_SIZE); 401 402 if (!page_size) 403 err("Unable to determine page size"); 404 if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2 405 > page_size) 406 err("Impossible to run this test"); 407 408 /* 409 * Whether we can test certain features depends not just on test type, 410 * but also on whether or not this particular kernel supports the 411 * feature. 412 */ 413 414 if (uffd_get_features(&features)) 415 err("failed to get available features"); 416 417 test_uffdio_wp = test_uffdio_wp && 418 (features & UFFD_FEATURE_PAGEFAULT_FLAG_WP); 419 420 if (test_type != TEST_ANON && !(features & UFFD_FEATURE_WP_HUGETLBFS_SHMEM)) 421 test_uffdio_wp = false; 422 423 close(uffd); 424 uffd = -1; 425 } 426 427 static void sigalrm(int sig) 428 { 429 if (sig != SIGALRM) 430 abort(); 431 test_uffdio_copy_eexist = true; 432 alarm(ALARM_INTERVAL_SECS); 433 } 434 435 int main(int argc, char **argv) 436 { 437 size_t bytes; 438 439 if (argc < 4) 440 usage(); 441 442 if (signal(SIGALRM, sigalrm) == SIG_ERR) 443 err("failed to arm SIGALRM"); 444 alarm(ALARM_INTERVAL_SECS); 445 446 parse_test_type_arg(argv[1]); 447 bytes = atol(argv[2]) * 1024 * 1024; 448 449 if (test_type == TEST_HUGETLB && 450 get_free_hugepages() < bytes / page_size) { 451 printf("skip: Skipping userfaultfd... not enough hugepages\n"); 452 return KSFT_SKIP; 453 } 454 455 nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); 456 457 nr_pages_per_cpu = bytes / page_size / nr_cpus; 458 if (!nr_pages_per_cpu) { 459 _err("invalid MiB"); 460 usage(); 461 } 462 463 bounces = atoi(argv[3]); 464 if (bounces <= 0) { 465 _err("invalid bounces"); 466 usage(); 467 } 468 nr_pages = nr_pages_per_cpu * nr_cpus; 469 470 printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n", 471 nr_pages, nr_pages_per_cpu); 472 return userfaultfd_stress(); 473 } 474