contrib/jemalloc/src/pages.c

   1 #define JEMALLOC_PAGES_C_
   2 #include "jemalloc/internal/jemalloc_preamble.h"
   3
   4 #include "jemalloc/internal/pages.h"
   5
   6 #include "jemalloc/internal/jemalloc_internal_includes.h"
   7
   8 #include "jemalloc/internal/assert.h"
   9 #include "jemalloc/internal/malloc_io.h"
  10
  11 #ifdef JEMALLOC_SYSCTL_VM_OVERCOMMIT
  12 #include <sys/sysctl.h>
  13 #ifdef __FreeBSD__
  14 #include <vm/vm_param.h>
  15 #endif
  16 #endif
  17
  18 /******************************************************************************/
  19 /* Data. */
  20
  21 /* Actual operating system page size, detected during bootstrap, <= PAGE. */
  22 static size_t   os_page;
  23
  24 #ifndef _WIN32
  25 #  define PAGES_PROT_COMMIT (PROT_READ | PROT_WRITE)
  26 #  define PAGES_PROT_DECOMMIT (PROT_NONE)
  27 static int      mmap_flags;
  28 #endif
  29 static bool     os_overcommits;
  30
  31 const char *thp_mode_names[] = {
  32         "default",
  33         "always",
  34         "never",
  35         "not supported"
  36 };
  37 thp_mode_t opt_thp = THP_MODE_DEFAULT;
  38 thp_mode_t init_system_thp_mode;
  39
  40 /* Runtime support for lazy purge. Irrelevant when !pages_can_purge_lazy. */
  41 static bool pages_can_purge_lazy_runtime = true;
  42
  43 /******************************************************************************/
  44 /*
  45  * Function prototypes for static functions that are referenced prior to
  46  * definition.
  47  */
  48
  49 static void os_pages_unmap(void *addr, size_t size);
  50
  51 /******************************************************************************/
  52
  53 static void *
  54 os_pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
  55         assert(ALIGNMENT_ADDR2BASE(addr, os_page) == addr);
  56         assert(ALIGNMENT_CEILING(size, os_page) == size);
  57         assert(size != 0);
  58
  59         if (os_overcommits) {
  60                 *commit = true;
  61         }
  62
  63         void *ret;
  64 #ifdef _WIN32
  65         /*
  66          * If VirtualAlloc can't allocate at the given address when one is
  67          * given, it fails and returns NULL.
  68          */
  69         ret = VirtualAlloc(addr, size, MEM_RESERVE | (*commit ? MEM_COMMIT : 0),
  70             PAGE_READWRITE);
  71 #else
  72         /*
  73          * We don't use MAP_FIXED here, because it can cause the *replacement*
  74          * of existing mappings, and we only want to create new mappings.
  75          */
  76         {
  77                 int prot = *commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
  78
  79                 ret = mmap(addr, size, prot, mmap_flags, -1, 0);
  80         }
  81         assert(ret != NULL);
  82
  83         if (ret == MAP_FAILED) {
  84                 ret = NULL;
  85         } else if (addr != NULL && ret != addr) {
  86                 /*
  87                  * We succeeded in mapping memory, but not in the right place.
  88                  */
  89                 os_pages_unmap(ret, size);
  90                 ret = NULL;
  91         }
  92 #endif
  93         assert(ret == NULL || (addr == NULL && ret != addr) || (addr != NULL &&
  94             ret == addr));
  95         return ret;
  96 }
  97
  98 static void *
  99 os_pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size,
 100     bool *commit) {
 101         void *ret = (void *)((uintptr_t)addr + leadsize);
 102
 103         assert(alloc_size >= leadsize + size);
 104 #ifdef _WIN32
 105         os_pages_unmap(addr, alloc_size);
 106         void *new_addr = os_pages_map(ret, size, PAGE, commit);
 107         if (new_addr == ret) {
 108                 return ret;
 109         }
 110         if (new_addr != NULL) {
 111                 os_pages_unmap(new_addr, size);
 112         }
 113         return NULL;
 114 #else
 115         size_t trailsize = alloc_size - leadsize - size;
 116
 117         if (leadsize != 0) {
 118                 os_pages_unmap(addr, leadsize);
 119         }
 120         if (trailsize != 0) {
 121                 os_pages_unmap((void *)((uintptr_t)ret + size), trailsize);
 122         }
 123         return ret;
 124 #endif
 125 }
 126
 127 static void
 128 os_pages_unmap(void *addr, size_t size) {
 129         assert(ALIGNMENT_ADDR2BASE(addr, os_page) == addr);
 130         assert(ALIGNMENT_CEILING(size, os_page) == size);
 131
 132 #ifdef _WIN32
 133         if (VirtualFree(addr, 0, MEM_RELEASE) == 0)
 134 #else
 135         if (munmap(addr, size) == -1)
 136 #endif
 137         {
 138                 char buf[BUFERROR_BUF];
 139
 140                 buferror(get_errno(), buf, sizeof(buf));
 141                 malloc_printf("<jemalloc>: Error in "
 142 #ifdef _WIN32
 143                     "VirtualFree"
 144 #else
 145                     "munmap"
 146 #endif
 147                     "(): %s\n", buf);
 148                 if (opt_abort) {
 149                         abort();
 150                 }
 151         }
 152 }
 153
 154 static void *
 155 pages_map_slow(size_t size, size_t alignment, bool *commit) {
 156         size_t alloc_size = size + alignment - os_page;
 157         /* Beware size_t wrap-around. */
 158         if (alloc_size < size) {
 159                 return NULL;
 160         }
 161
 162         void *ret;
 163         do {
 164                 void *pages = os_pages_map(NULL, alloc_size, alignment, commit);
 165                 if (pages == NULL) {
 166                         return NULL;
 167                 }
 168                 size_t leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment)
 169                     - (uintptr_t)pages;
 170                 ret = os_pages_trim(pages, alloc_size, leadsize, size, commit);
 171         } while (ret == NULL);
 172
 173         assert(ret != NULL);
 174         assert(PAGE_ADDR2BASE(ret) == ret);
 175         return ret;
 176 }
 177
 178 void *
 179 pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
 180         assert(alignment >= PAGE);
 181         assert(ALIGNMENT_ADDR2BASE(addr, alignment) == addr);
 182
 183         /*
 184          * Ideally, there would be a way to specify alignment to mmap() (like
 185          * NetBSD has), but in the absence of such a feature, we have to work
 186          * hard to efficiently create aligned mappings.  The reliable, but
 187          * slow method is to create a mapping that is over-sized, then trim the
 188          * excess.  However, that always results in one or two calls to
 189          * os_pages_unmap(), and it can leave holes in the process's virtual
 190          * memory map if memory grows downward.
 191          *
 192          * Optimistically try mapping precisely the right amount before falling
 193          * back to the slow method, with the expectation that the optimistic
 194          * approach works most of the time.
 195          */
 196
 197         void *ret = os_pages_map(addr, size, os_page, commit);
 198         if (ret == NULL || ret == addr) {
 199                 return ret;
 200         }
 201         assert(addr == NULL);
 202         if (ALIGNMENT_ADDR2OFFSET(ret, alignment) != 0) {
 203                 os_pages_unmap(ret, size);
 204                 return pages_map_slow(size, alignment, commit);
 205         }
 206
 207         assert(PAGE_ADDR2BASE(ret) == ret);
 208         return ret;
 209 }
 210
 211 void
 212 pages_unmap(void *addr, size_t size) {
 213         assert(PAGE_ADDR2BASE(addr) == addr);
 214         assert(PAGE_CEILING(size) == size);
 215
 216         os_pages_unmap(addr, size);
 217 }
 218
 219 static bool
 220 pages_commit_impl(void *addr, size_t size, bool commit) {
 221         assert(PAGE_ADDR2BASE(addr) == addr);
 222         assert(PAGE_CEILING(size) == size);
 223
 224         if (os_overcommits) {
 225                 return true;
 226         }
 227
 228 #ifdef _WIN32
 229         return (commit ? (addr != VirtualAlloc(addr, size, MEM_COMMIT,
 230             PAGE_READWRITE)) : (!VirtualFree(addr, size, MEM_DECOMMIT)));
 231 #else
 232         {
 233                 int prot = commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
 234                 void *result = mmap(addr, size, prot, mmap_flags | MAP_FIXED,
 235                     -1, 0);
 236                 if (result == MAP_FAILED) {
 237                         return true;
 238                 }
 239                 if (result != addr) {
 240                         /*
 241                          * We succeeded in mapping memory, but not in the right
 242                          * place.
 243                          */
 244                         os_pages_unmap(result, size);
 245                         return true;
 246                 }
 247                 return false;
 248         }
 249 #endif
 250 }
 251
 252 bool
 253 pages_commit(void *addr, size_t size) {
 254         return pages_commit_impl(addr, size, true);
 255 }
 256
 257 bool
 258 pages_decommit(void *addr, size_t size) {
 259         return pages_commit_impl(addr, size, false);
 260 }
 261
 262 bool
 263 pages_purge_lazy(void *addr, size_t size) {
 264         assert(PAGE_ADDR2BASE(addr) == addr);
 265         assert(PAGE_CEILING(size) == size);
 266
 267         if (!pages_can_purge_lazy) {
 268                 return true;
 269         }
 270         if (!pages_can_purge_lazy_runtime) {
 271                 /*
 272                  * Built with lazy purge enabled, but detected it was not
 273                  * supported on the current system.
 274                  */
 275                 return true;
 276         }
 277
 278 #ifdef _WIN32
 279         VirtualAlloc(addr, size, MEM_RESET, PAGE_READWRITE);
 280         return false;
 281 #elif defined(JEMALLOC_PURGE_MADVISE_FREE)
 282         return (madvise(addr, size,
 283 #  ifdef MADV_FREE
 284             MADV_FREE
 285 #  else
 286             JEMALLOC_MADV_FREE
 287 #  endif
 288             ) != 0);
 289 #elif defined(JEMALLOC_PURGE_MADVISE_DONTNEED) && \
 290     !defined(JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS)
 291         return (madvise(addr, size, MADV_DONTNEED) != 0);
 292 #else
 293         not_reached();
 294 #endif
 295 }
 296
 297 bool
 298 pages_purge_forced(void *addr, size_t size) {
 299         assert(PAGE_ADDR2BASE(addr) == addr);
 300         assert(PAGE_CEILING(size) == size);
 301
 302         if (!pages_can_purge_forced) {
 303                 return true;
 304         }
 305
 306 #if defined(JEMALLOC_PURGE_MADVISE_DONTNEED) && \
 307     defined(JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS)
 308         return (madvise(addr, size, MADV_DONTNEED) != 0);
 309 #elif defined(JEMALLOC_MAPS_COALESCE)
 310         /* Try to overlay a new demand-zeroed mapping. */
 311         return pages_commit(addr, size);
 312 #else
 313         not_reached();
 314 #endif
 315 }
 316
 317 static bool
 318 pages_huge_impl(void *addr, size_t size, bool aligned) {
 319         if (aligned) {
 320                 assert(HUGEPAGE_ADDR2BASE(addr) == addr);
 321                 assert(HUGEPAGE_CEILING(size) == size);
 322         }
 323 #ifdef JEMALLOC_HAVE_MADVISE_HUGE
 324         return (madvise(addr, size, MADV_HUGEPAGE) != 0);
 325 #else
 326         return true;
 327 #endif
 328 }
 329
 330 bool
 331 pages_huge(void *addr, size_t size) {
 332         return pages_huge_impl(addr, size, true);
 333 }
 334
 335 static bool
 336 pages_huge_unaligned(void *addr, size_t size) {
 337         return pages_huge_impl(addr, size, false);
 338 }
 339
 340 static bool
 341 pages_nohuge_impl(void *addr, size_t size, bool aligned) {
 342         if (aligned) {
 343                 assert(HUGEPAGE_ADDR2BASE(addr) == addr);
 344                 assert(HUGEPAGE_CEILING(size) == size);
 345         }
 346
 347 #ifdef JEMALLOC_HAVE_MADVISE_HUGE
 348         return (madvise(addr, size, MADV_NOHUGEPAGE) != 0);
 349 #else
 350         return false;
 351 #endif
 352 }
 353
 354 bool
 355 pages_nohuge(void *addr, size_t size) {
 356         return pages_nohuge_impl(addr, size, true);
 357 }
 358
 359 static bool
 360 pages_nohuge_unaligned(void *addr, size_t size) {
 361         return pages_nohuge_impl(addr, size, false);
 362 }
 363
 364 bool
 365 pages_dontdump(void *addr, size_t size) {
 366         assert(PAGE_ADDR2BASE(addr) == addr);
 367         assert(PAGE_CEILING(size) == size);
 368 #ifdef JEMALLOC_MADVISE_DONTDUMP
 369         return madvise(addr, size, MADV_DONTDUMP) != 0;
 370 #else
 371         return false;
 372 #endif
 373 }
 374
 375 bool
 376 pages_dodump(void *addr, size_t size) {
 377         assert(PAGE_ADDR2BASE(addr) == addr);
 378         assert(PAGE_CEILING(size) == size);
 379 #ifdef JEMALLOC_MADVISE_DONTDUMP
 380         return madvise(addr, size, MADV_DODUMP) != 0;
 381 #else
 382         return false;
 383 #endif
 384 }
 385
 386
 387 static size_t
 388 os_page_detect(void) {
 389 #ifdef _WIN32
 390         SYSTEM_INFO si;
 391         GetSystemInfo(&si);
 392         return si.dwPageSize;
 393 #elif defined(__FreeBSD__)
 394         return getpagesize();
 395 #else
 396         long result = sysconf(_SC_PAGESIZE);
 397         if (result == -1) {
 398                 return LG_PAGE;
 399         }
 400         return (size_t)result;
 401 #endif
 402 }
 403
 404 #ifdef JEMALLOC_SYSCTL_VM_OVERCOMMIT
 405 static bool
 406 os_overcommits_sysctl(void) {
 407         int vm_overcommit;
 408         size_t sz;
 409
 410         sz = sizeof(vm_overcommit);
 411 #if defined(__FreeBSD__) && defined(VM_OVERCOMMIT)
 412         int mib[2];
 413
 414         mib[0] = CTL_VM;
 415         mib[1] = VM_OVERCOMMIT;
 416         if (sysctl(mib, 2, &vm_overcommit, &sz, NULL, 0) != 0) {
 417                 return false; /* Error. */
 418         }
 419 #else
 420         if (sysctlbyname("vm.overcommit", &vm_overcommit, &sz, NULL, 0) != 0) {
 421                 return false; /* Error. */
 422         }
 423 #endif
 424
 425         return ((vm_overcommit & 0x3) == 0);
 426 }
 427 #endif
 428
 429 #ifdef JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY
 430 /*
 431  * Use syscall(2) rather than {open,read,close}(2) when possible to avoid
 432  * reentry during bootstrapping if another library has interposed system call
 433  * wrappers.
 434  */
 435 static bool
 436 os_overcommits_proc(void) {
 437         int fd;
 438         char buf[1];
 439
 440 #if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_open)
 441         #if defined(O_CLOEXEC)
 442                 fd = (int)syscall(SYS_open, "/proc/sys/vm/overcommit_memory", O_RDONLY |
 443                         O_CLOEXEC);
 444         #else
 445                 fd = (int)syscall(SYS_open, "/proc/sys/vm/overcommit_memory", O_RDONLY);
 446                 if (fd != -1) {
 447                         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 448                 }
 449         #endif
 450 #elif defined(JEMALLOC_USE_SYSCALL) && defined(SYS_openat)
 451         #if defined(O_CLOEXEC)
 452                 fd = (int)syscall(SYS_openat,
 453                         AT_FDCWD, "/proc/sys/vm/overcommit_memory", O_RDONLY | O_CLOEXEC);
 454         #else
 455                 fd = (int)syscall(SYS_openat,
 456                         AT_FDCWD, "/proc/sys/vm/overcommit_memory", O_RDONLY);
 457                 if (fd != -1) {
 458                         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 459                 }
 460         #endif
 461 #else
 462         #if defined(O_CLOEXEC)
 463                 fd = open("/proc/sys/vm/overcommit_memory", O_RDONLY | O_CLOEXEC);
 464         #else
 465                 fd = open("/proc/sys/vm/overcommit_memory", O_RDONLY);
 466                 if (fd != -1) {
 467                         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 468                 }
 469         #endif
 470 #endif
 471
 472         if (fd == -1) {
 473                 return false; /* Error. */
 474         }
 475
 476         ssize_t nread = malloc_read_fd(fd, &buf, sizeof(buf));
 477 #if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_close)
 478         syscall(SYS_close, fd);
 479 #else
 480         close(fd);
 481 #endif
 482
 483         if (nread < 1) {
 484                 return false; /* Error. */
 485         }
 486         /*
 487          * /proc/sys/vm/overcommit_memory meanings:
 488          * 0: Heuristic overcommit.
 489          * 1: Always overcommit.
 490          * 2: Never overcommit.
 491          */
 492         return (buf[0] == '0' || buf[0] == '1');
 493 }
 494 #endif
 495
 496 void
 497 pages_set_thp_state (void *ptr, size_t size) {
 498         if (opt_thp == thp_mode_default || opt_thp == init_system_thp_mode) {
 499                 return;
 500         }
 501         assert(opt_thp != thp_mode_not_supported &&
 502             init_system_thp_mode != thp_mode_not_supported);
 503
 504         if (opt_thp == thp_mode_always
 505             && init_system_thp_mode != thp_mode_never) {
 506                 assert(init_system_thp_mode == thp_mode_default);
 507                 pages_huge_unaligned(ptr, size);
 508         } else if (opt_thp == thp_mode_never) {
 509                 assert(init_system_thp_mode == thp_mode_default ||
 510                     init_system_thp_mode == thp_mode_always);
 511                 pages_nohuge_unaligned(ptr, size);
 512         }
 513 }
 514
 515 static void
 516 init_thp_state(void) {
 517         if (!have_madvise_huge) {
 518                 if (metadata_thp_enabled() && opt_abort) {
 519                         malloc_write("<jemalloc>: no MADV_HUGEPAGE support\n");
 520                         abort();
 521                 }
 522                 goto label_error;
 523         }
 524
 525         static const char sys_state_madvise[] = "always [madvise] never\n";
 526         static const char sys_state_always[] = "[always] madvise never\n";
 527         static const char sys_state_never[] = "always madvise [never]\n";
 528         char buf[sizeof(sys_state_madvise)];
 529
 530 #if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_open)
 531         int fd = (int)syscall(SYS_open,
 532             "/sys/kernel/mm/transparent_hugepage/enabled", O_RDONLY);
 533 #else
 534         int fd = open("/sys/kernel/mm/transparent_hugepage/enabled", O_RDONLY);
 535 #endif
 536         if (fd == -1) {
 537                 goto label_error;
 538         }
 539
 540         ssize_t nread = malloc_read_fd(fd, &buf, sizeof(buf));
 541 #if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_close)
 542         syscall(SYS_close, fd);
 543 #else
 544         close(fd);
 545 #endif
 546
 547         if (strncmp(buf, sys_state_madvise, (size_t)nread) == 0) {
 548                 init_system_thp_mode = thp_mode_default;
 549         } else if (strncmp(buf, sys_state_always, (size_t)nread) == 0) {
 550                 init_system_thp_mode = thp_mode_always;
 551         } else if (strncmp(buf, sys_state_never, (size_t)nread) == 0) {
 552                 init_system_thp_mode = thp_mode_never;
 553         } else {
 554                 goto label_error;
 555         }
 556         return;
 557 label_error:
 558         opt_thp = init_system_thp_mode = thp_mode_not_supported;
 559 }
 560
 561 bool
 562 pages_boot(void) {
 563         os_page = os_page_detect();
 564         if (os_page > PAGE) {
 565                 malloc_write("<jemalloc>: Unsupported system page size\n");
 566                 if (opt_abort) {
 567                         abort();
 568                 }
 569                 return true;
 570         }
 571
 572 #ifndef _WIN32
 573         mmap_flags = MAP_PRIVATE | MAP_ANON;
 574 #endif
 575
 576 #ifdef JEMALLOC_SYSCTL_VM_OVERCOMMIT
 577         os_overcommits = os_overcommits_sysctl();
 578 #elif defined(JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY)
 579         os_overcommits = os_overcommits_proc();
 580 #  ifdef MAP_NORESERVE
 581         if (os_overcommits) {
 582                 mmap_flags |= MAP_NORESERVE;
 583         }
 584 #  endif
 585 #else
 586         os_overcommits = false;
 587 #endif
 588
 589         init_thp_state();
 590
 591         /* Detect lazy purge runtime support. */
 592         if (pages_can_purge_lazy) {
 593                 bool committed = false;
 594                 void *madv_free_page = os_pages_map(NULL, PAGE, PAGE, &committed);
 595                 if (madv_free_page == NULL) {
 596                         return true;
 597                 }
 598                 assert(pages_can_purge_lazy_runtime);
 599                 if (pages_purge_lazy(madv_free_page, PAGE)) {
 600                         pages_can_purge_lazy_runtime = false;
 601                 }
 602                 os_pages_unmap(madv_free_page, PAGE);
 603         }
 604
 605         return false;
 606 }