1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2009 Red Hat, Inc. 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/mm.h> 9 #include <linux/sched.h> 10 #include <linux/sched/mm.h> 11 #include <linux/sched/coredump.h> 12 #include <linux/sched/numa_balancing.h> 13 #include <linux/highmem.h> 14 #include <linux/hugetlb.h> 15 #include <linux/mmu_notifier.h> 16 #include <linux/rmap.h> 17 #include <linux/swap.h> 18 #include <linux/shrinker.h> 19 #include <linux/mm_inline.h> 20 #include <linux/swapops.h> 21 #include <linux/backing-dev.h> 22 #include <linux/dax.h> 23 #include <linux/khugepaged.h> 24 #include <linux/freezer.h> 25 #include <linux/pfn_t.h> 26 #include <linux/mman.h> 27 #include <linux/memremap.h> 28 #include <linux/pagemap.h> 29 #include <linux/debugfs.h> 30 #include <linux/migrate.h> 31 #include <linux/hashtable.h> 32 #include <linux/userfaultfd_k.h> 33 #include <linux/page_idle.h> 34 #include <linux/shmem_fs.h> 35 #include <linux/oom.h> 36 #include <linux/numa.h> 37 #include <linux/page_owner.h> 38 #include <linux/sched/sysctl.h> 39 40 #include <asm/tlb.h> 41 #include <asm/pgalloc.h> 42 #include "internal.h" 43 #include "swap.h" 44 45 #define CREATE_TRACE_POINTS 46 #include <trace/events/thp.h> 47 48 /* 49 * By default, transparent hugepage support is disabled in order to avoid 50 * risking an increased memory footprint for applications that are not 51 * guaranteed to benefit from it. When transparent hugepage support is 52 * enabled, it is for all mappings, and khugepaged scans all mappings. 53 * Defrag is invoked by khugepaged hugepage allocations and by page faults 54 * for all hugepage allocations. 55 */ 56 unsigned long transparent_hugepage_flags __read_mostly = 57 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 58 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 59 #endif 60 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 61 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 62 #endif 63 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 64 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 65 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 66 67 static struct shrinker deferred_split_shrinker; 68 69 static atomic_t huge_zero_refcount; 70 struct page *huge_zero_page __read_mostly; 71 unsigned long huge_zero_pfn __read_mostly = ~0UL; 72 73 bool hugepage_vma_check(struct vm_area_struct *vma, 74 unsigned long vm_flags, 75 bool smaps, bool in_pf) 76 { 77 if (!vma->vm_mm) /* vdso */ 78 return false; 79 80 /* 81 * Explicitly disabled through madvise or prctl, or some 82 * architectures may disable THP for some mappings, for 83 * example, s390 kvm. 84 * */ 85 if ((vm_flags & VM_NOHUGEPAGE) || 86 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) 87 return false; 88 /* 89 * If the hardware/firmware marked hugepage support disabled. 90 */ 91 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX)) 92 return false; 93 94 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 95 if (vma_is_dax(vma)) 96 return in_pf; 97 98 /* 99 * Special VMA and hugetlb VMA. 100 * Must be checked after dax since some dax mappings may have 101 * VM_MIXEDMAP set. 102 */ 103 if (vm_flags & VM_NO_KHUGEPAGED) 104 return false; 105 106 /* 107 * Check alignment for file vma and size for both file and anon vma. 108 * 109 * Skip the check for page fault. Huge fault does the check in fault 110 * handlers. And this check is not suitable for huge PUD fault. 111 */ 112 if (!in_pf && 113 !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) 114 return false; 115 116 /* 117 * Enabled via shmem mount options or sysfs settings. 118 * Must be done before hugepage flags check since shmem has its 119 * own flags. 120 */ 121 if (!in_pf && shmem_file(vma->vm_file)) 122 return shmem_huge_enabled(vma); 123 124 if (!hugepage_flags_enabled()) 125 return false; 126 127 /* THP settings require madvise. */ 128 if (!(vm_flags & VM_HUGEPAGE) && !hugepage_flags_always()) 129 return false; 130 131 /* Only regular file is valid */ 132 if (!in_pf && file_thp_enabled(vma)) 133 return true; 134 135 if (!vma_is_anonymous(vma)) 136 return false; 137 138 if (vma_is_temporary_stack(vma)) 139 return false; 140 141 /* 142 * THPeligible bit of smaps should show 1 for proper VMAs even 143 * though anon_vma is not initialized yet. 144 * 145 * Allow page fault since anon_vma may be not initialized until 146 * the first page fault. 147 */ 148 if (!vma->anon_vma) 149 return (smaps || in_pf); 150 151 return true; 152 } 153 154 static bool get_huge_zero_page(void) 155 { 156 struct page *zero_page; 157 retry: 158 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 159 return true; 160 161 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 162 HPAGE_PMD_ORDER); 163 if (!zero_page) { 164 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 165 return false; 166 } 167 count_vm_event(THP_ZERO_PAGE_ALLOC); 168 preempt_disable(); 169 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 170 preempt_enable(); 171 __free_pages(zero_page, compound_order(zero_page)); 172 goto retry; 173 } 174 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 175 176 /* We take additional reference here. It will be put back by shrinker */ 177 atomic_set(&huge_zero_refcount, 2); 178 preempt_enable(); 179 return true; 180 } 181 182 static void put_huge_zero_page(void) 183 { 184 /* 185 * Counter should never go to zero here. Only shrinker can put 186 * last reference. 187 */ 188 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 189 } 190 191 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 192 { 193 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 194 return READ_ONCE(huge_zero_page); 195 196 if (!get_huge_zero_page()) 197 return NULL; 198 199 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 200 put_huge_zero_page(); 201 202 return READ_ONCE(huge_zero_page); 203 } 204 205 void mm_put_huge_zero_page(struct mm_struct *mm) 206 { 207 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 208 put_huge_zero_page(); 209 } 210 211 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 212 struct shrink_control *sc) 213 { 214 /* we can free zero page only if last reference remains */ 215 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 216 } 217 218 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 219 struct shrink_control *sc) 220 { 221 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 222 struct page *zero_page = xchg(&huge_zero_page, NULL); 223 BUG_ON(zero_page == NULL); 224 WRITE_ONCE(huge_zero_pfn, ~0UL); 225 __free_pages(zero_page, compound_order(zero_page)); 226 return HPAGE_PMD_NR; 227 } 228 229 return 0; 230 } 231 232 static struct shrinker huge_zero_page_shrinker = { 233 .count_objects = shrink_huge_zero_page_count, 234 .scan_objects = shrink_huge_zero_page_scan, 235 .seeks = DEFAULT_SEEKS, 236 }; 237 238 #ifdef CONFIG_SYSFS 239 static ssize_t enabled_show(struct kobject *kobj, 240 struct kobj_attribute *attr, char *buf) 241 { 242 const char *output; 243 244 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 245 output = "[always] madvise never"; 246 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 247 &transparent_hugepage_flags)) 248 output = "always [madvise] never"; 249 else 250 output = "always madvise [never]"; 251 252 return sysfs_emit(buf, "%s\n", output); 253 } 254 255 static ssize_t enabled_store(struct kobject *kobj, 256 struct kobj_attribute *attr, 257 const char *buf, size_t count) 258 { 259 ssize_t ret = count; 260 261 if (sysfs_streq(buf, "always")) { 262 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 263 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 264 } else if (sysfs_streq(buf, "madvise")) { 265 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 266 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 267 } else if (sysfs_streq(buf, "never")) { 268 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 269 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 270 } else 271 ret = -EINVAL; 272 273 if (ret > 0) { 274 int err = start_stop_khugepaged(); 275 if (err) 276 ret = err; 277 } 278 return ret; 279 } 280 281 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 282 283 ssize_t single_hugepage_flag_show(struct kobject *kobj, 284 struct kobj_attribute *attr, char *buf, 285 enum transparent_hugepage_flag flag) 286 { 287 return sysfs_emit(buf, "%d\n", 288 !!test_bit(flag, &transparent_hugepage_flags)); 289 } 290 291 ssize_t single_hugepage_flag_store(struct kobject *kobj, 292 struct kobj_attribute *attr, 293 const char *buf, size_t count, 294 enum transparent_hugepage_flag flag) 295 { 296 unsigned long value; 297 int ret; 298 299 ret = kstrtoul(buf, 10, &value); 300 if (ret < 0) 301 return ret; 302 if (value > 1) 303 return -EINVAL; 304 305 if (value) 306 set_bit(flag, &transparent_hugepage_flags); 307 else 308 clear_bit(flag, &transparent_hugepage_flags); 309 310 return count; 311 } 312 313 static ssize_t defrag_show(struct kobject *kobj, 314 struct kobj_attribute *attr, char *buf) 315 { 316 const char *output; 317 318 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 319 &transparent_hugepage_flags)) 320 output = "[always] defer defer+madvise madvise never"; 321 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 322 &transparent_hugepage_flags)) 323 output = "always [defer] defer+madvise madvise never"; 324 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 325 &transparent_hugepage_flags)) 326 output = "always defer [defer+madvise] madvise never"; 327 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 328 &transparent_hugepage_flags)) 329 output = "always defer defer+madvise [madvise] never"; 330 else 331 output = "always defer defer+madvise madvise [never]"; 332 333 return sysfs_emit(buf, "%s\n", output); 334 } 335 336 static ssize_t defrag_store(struct kobject *kobj, 337 struct kobj_attribute *attr, 338 const char *buf, size_t count) 339 { 340 if (sysfs_streq(buf, "always")) { 341 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 342 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 343 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 344 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 345 } else if (sysfs_streq(buf, "defer+madvise")) { 346 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 348 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 349 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 350 } else if (sysfs_streq(buf, "defer")) { 351 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 353 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 354 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 355 } else if (sysfs_streq(buf, "madvise")) { 356 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 358 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 359 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 360 } else if (sysfs_streq(buf, "never")) { 361 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 364 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 365 } else 366 return -EINVAL; 367 368 return count; 369 } 370 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 371 372 static ssize_t use_zero_page_show(struct kobject *kobj, 373 struct kobj_attribute *attr, char *buf) 374 { 375 return single_hugepage_flag_show(kobj, attr, buf, 376 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 377 } 378 static ssize_t use_zero_page_store(struct kobject *kobj, 379 struct kobj_attribute *attr, const char *buf, size_t count) 380 { 381 return single_hugepage_flag_store(kobj, attr, buf, count, 382 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 383 } 384 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 385 386 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 387 struct kobj_attribute *attr, char *buf) 388 { 389 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 390 } 391 static struct kobj_attribute hpage_pmd_size_attr = 392 __ATTR_RO(hpage_pmd_size); 393 394 static struct attribute *hugepage_attr[] = { 395 &enabled_attr.attr, 396 &defrag_attr.attr, 397 &use_zero_page_attr.attr, 398 &hpage_pmd_size_attr.attr, 399 #ifdef CONFIG_SHMEM 400 &shmem_enabled_attr.attr, 401 #endif 402 NULL, 403 }; 404 405 static const struct attribute_group hugepage_attr_group = { 406 .attrs = hugepage_attr, 407 }; 408 409 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 410 { 411 int err; 412 413 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 414 if (unlikely(!*hugepage_kobj)) { 415 pr_err("failed to create transparent hugepage kobject\n"); 416 return -ENOMEM; 417 } 418 419 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 420 if (err) { 421 pr_err("failed to register transparent hugepage group\n"); 422 goto delete_obj; 423 } 424 425 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 426 if (err) { 427 pr_err("failed to register transparent hugepage group\n"); 428 goto remove_hp_group; 429 } 430 431 return 0; 432 433 remove_hp_group: 434 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 435 delete_obj: 436 kobject_put(*hugepage_kobj); 437 return err; 438 } 439 440 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 441 { 442 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 443 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 444 kobject_put(hugepage_kobj); 445 } 446 #else 447 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 448 { 449 return 0; 450 } 451 452 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 453 { 454 } 455 #endif /* CONFIG_SYSFS */ 456 457 static int __init hugepage_init(void) 458 { 459 int err; 460 struct kobject *hugepage_kobj; 461 462 if (!has_transparent_hugepage()) { 463 /* 464 * Hardware doesn't support hugepages, hence disable 465 * DAX PMD support. 466 */ 467 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 468 return -EINVAL; 469 } 470 471 /* 472 * hugepages can't be allocated by the buddy allocator 473 */ 474 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 475 /* 476 * we use page->mapping and page->index in second tail page 477 * as list_head: assuming THP order >= 2 478 */ 479 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 480 481 err = hugepage_init_sysfs(&hugepage_kobj); 482 if (err) 483 goto err_sysfs; 484 485 err = khugepaged_init(); 486 if (err) 487 goto err_slab; 488 489 err = register_shrinker(&huge_zero_page_shrinker, "thp-zero"); 490 if (err) 491 goto err_hzp_shrinker; 492 err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split"); 493 if (err) 494 goto err_split_shrinker; 495 496 /* 497 * By default disable transparent hugepages on smaller systems, 498 * where the extra memory used could hurt more than TLB overhead 499 * is likely to save. The admin can still enable it through /sys. 500 */ 501 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 502 transparent_hugepage_flags = 0; 503 return 0; 504 } 505 506 err = start_stop_khugepaged(); 507 if (err) 508 goto err_khugepaged; 509 510 return 0; 511 err_khugepaged: 512 unregister_shrinker(&deferred_split_shrinker); 513 err_split_shrinker: 514 unregister_shrinker(&huge_zero_page_shrinker); 515 err_hzp_shrinker: 516 khugepaged_destroy(); 517 err_slab: 518 hugepage_exit_sysfs(hugepage_kobj); 519 err_sysfs: 520 return err; 521 } 522 subsys_initcall(hugepage_init); 523 524 static int __init setup_transparent_hugepage(char *str) 525 { 526 int ret = 0; 527 if (!str) 528 goto out; 529 if (!strcmp(str, "always")) { 530 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 531 &transparent_hugepage_flags); 532 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 533 &transparent_hugepage_flags); 534 ret = 1; 535 } else if (!strcmp(str, "madvise")) { 536 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 537 &transparent_hugepage_flags); 538 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 539 &transparent_hugepage_flags); 540 ret = 1; 541 } else if (!strcmp(str, "never")) { 542 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 543 &transparent_hugepage_flags); 544 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 545 &transparent_hugepage_flags); 546 ret = 1; 547 } 548 out: 549 if (!ret) 550 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 551 return ret; 552 } 553 __setup("transparent_hugepage=", setup_transparent_hugepage); 554 555 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 556 { 557 if (likely(vma->vm_flags & VM_WRITE)) 558 pmd = pmd_mkwrite(pmd); 559 return pmd; 560 } 561 562 #ifdef CONFIG_MEMCG 563 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 564 { 565 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 566 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 567 568 if (memcg) 569 return &memcg->deferred_split_queue; 570 else 571 return &pgdat->deferred_split_queue; 572 } 573 #else 574 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 575 { 576 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 577 578 return &pgdat->deferred_split_queue; 579 } 580 #endif 581 582 void prep_transhuge_page(struct page *page) 583 { 584 /* 585 * we use page->mapping and page->index in second tail page 586 * as list_head: assuming THP order >= 2 587 */ 588 589 INIT_LIST_HEAD(page_deferred_list(page)); 590 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 591 } 592 593 static inline bool is_transparent_hugepage(struct page *page) 594 { 595 if (!PageCompound(page)) 596 return false; 597 598 page = compound_head(page); 599 return is_huge_zero_page(page) || 600 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 601 } 602 603 static unsigned long __thp_get_unmapped_area(struct file *filp, 604 unsigned long addr, unsigned long len, 605 loff_t off, unsigned long flags, unsigned long size) 606 { 607 loff_t off_end = off + len; 608 loff_t off_align = round_up(off, size); 609 unsigned long len_pad, ret; 610 611 if (off_end <= off_align || (off_end - off_align) < size) 612 return 0; 613 614 len_pad = len + size; 615 if (len_pad < len || (off + len_pad) < off) 616 return 0; 617 618 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 619 off >> PAGE_SHIFT, flags); 620 621 /* 622 * The failure might be due to length padding. The caller will retry 623 * without the padding. 624 */ 625 if (IS_ERR_VALUE(ret)) 626 return 0; 627 628 /* 629 * Do not try to align to THP boundary if allocation at the address 630 * hint succeeds. 631 */ 632 if (ret == addr) 633 return addr; 634 635 ret += (off - ret) & (size - 1); 636 return ret; 637 } 638 639 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 640 unsigned long len, unsigned long pgoff, unsigned long flags) 641 { 642 unsigned long ret; 643 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 644 645 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 646 if (ret) 647 return ret; 648 649 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 650 } 651 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 652 653 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 654 struct page *page, gfp_t gfp) 655 { 656 struct vm_area_struct *vma = vmf->vma; 657 pgtable_t pgtable; 658 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 659 vm_fault_t ret = 0; 660 661 VM_BUG_ON_PAGE(!PageCompound(page), page); 662 663 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) { 664 put_page(page); 665 count_vm_event(THP_FAULT_FALLBACK); 666 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 667 return VM_FAULT_FALLBACK; 668 } 669 cgroup_throttle_swaprate(page, gfp); 670 671 pgtable = pte_alloc_one(vma->vm_mm); 672 if (unlikely(!pgtable)) { 673 ret = VM_FAULT_OOM; 674 goto release; 675 } 676 677 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 678 /* 679 * The memory barrier inside __SetPageUptodate makes sure that 680 * clear_huge_page writes become visible before the set_pmd_at() 681 * write. 682 */ 683 __SetPageUptodate(page); 684 685 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 686 if (unlikely(!pmd_none(*vmf->pmd))) { 687 goto unlock_release; 688 } else { 689 pmd_t entry; 690 691 ret = check_stable_address_space(vma->vm_mm); 692 if (ret) 693 goto unlock_release; 694 695 /* Deliver the page fault to userland */ 696 if (userfaultfd_missing(vma)) { 697 spin_unlock(vmf->ptl); 698 put_page(page); 699 pte_free(vma->vm_mm, pgtable); 700 ret = handle_userfault(vmf, VM_UFFD_MISSING); 701 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 702 return ret; 703 } 704 705 entry = mk_huge_pmd(page, vma->vm_page_prot); 706 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 707 page_add_new_anon_rmap(page, vma, haddr); 708 lru_cache_add_inactive_or_unevictable(page, vma); 709 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 710 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 711 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 712 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 713 mm_inc_nr_ptes(vma->vm_mm); 714 spin_unlock(vmf->ptl); 715 count_vm_event(THP_FAULT_ALLOC); 716 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 717 } 718 719 return 0; 720 unlock_release: 721 spin_unlock(vmf->ptl); 722 release: 723 if (pgtable) 724 pte_free(vma->vm_mm, pgtable); 725 put_page(page); 726 return ret; 727 728 } 729 730 /* 731 * always: directly stall for all thp allocations 732 * defer: wake kswapd and fail if not immediately available 733 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 734 * fail if not immediately available 735 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 736 * available 737 * never: never stall for any thp allocation 738 */ 739 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 740 { 741 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 742 743 /* Always do synchronous compaction */ 744 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 745 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 746 747 /* Kick kcompactd and fail quickly */ 748 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 749 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 750 751 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 752 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 753 return GFP_TRANSHUGE_LIGHT | 754 (vma_madvised ? __GFP_DIRECT_RECLAIM : 755 __GFP_KSWAPD_RECLAIM); 756 757 /* Only do synchronous compaction if madvised */ 758 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 759 return GFP_TRANSHUGE_LIGHT | 760 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 761 762 return GFP_TRANSHUGE_LIGHT; 763 } 764 765 /* Caller must hold page table lock. */ 766 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 767 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 768 struct page *zero_page) 769 { 770 pmd_t entry; 771 if (!pmd_none(*pmd)) 772 return; 773 entry = mk_pmd(zero_page, vma->vm_page_prot); 774 entry = pmd_mkhuge(entry); 775 if (pgtable) 776 pgtable_trans_huge_deposit(mm, pmd, pgtable); 777 set_pmd_at(mm, haddr, pmd, entry); 778 mm_inc_nr_ptes(mm); 779 } 780 781 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 782 { 783 struct vm_area_struct *vma = vmf->vma; 784 gfp_t gfp; 785 struct folio *folio; 786 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 787 788 if (!transhuge_vma_suitable(vma, haddr)) 789 return VM_FAULT_FALLBACK; 790 if (unlikely(anon_vma_prepare(vma))) 791 return VM_FAULT_OOM; 792 khugepaged_enter_vma(vma, vma->vm_flags); 793 794 if (!(vmf->flags & FAULT_FLAG_WRITE) && 795 !mm_forbids_zeropage(vma->vm_mm) && 796 transparent_hugepage_use_zero_page()) { 797 pgtable_t pgtable; 798 struct page *zero_page; 799 vm_fault_t ret; 800 pgtable = pte_alloc_one(vma->vm_mm); 801 if (unlikely(!pgtable)) 802 return VM_FAULT_OOM; 803 zero_page = mm_get_huge_zero_page(vma->vm_mm); 804 if (unlikely(!zero_page)) { 805 pte_free(vma->vm_mm, pgtable); 806 count_vm_event(THP_FAULT_FALLBACK); 807 return VM_FAULT_FALLBACK; 808 } 809 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 810 ret = 0; 811 if (pmd_none(*vmf->pmd)) { 812 ret = check_stable_address_space(vma->vm_mm); 813 if (ret) { 814 spin_unlock(vmf->ptl); 815 pte_free(vma->vm_mm, pgtable); 816 } else if (userfaultfd_missing(vma)) { 817 spin_unlock(vmf->ptl); 818 pte_free(vma->vm_mm, pgtable); 819 ret = handle_userfault(vmf, VM_UFFD_MISSING); 820 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 821 } else { 822 set_huge_zero_page(pgtable, vma->vm_mm, vma, 823 haddr, vmf->pmd, zero_page); 824 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 825 spin_unlock(vmf->ptl); 826 } 827 } else { 828 spin_unlock(vmf->ptl); 829 pte_free(vma->vm_mm, pgtable); 830 } 831 return ret; 832 } 833 gfp = vma_thp_gfp_mask(vma); 834 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); 835 if (unlikely(!folio)) { 836 count_vm_event(THP_FAULT_FALLBACK); 837 return VM_FAULT_FALLBACK; 838 } 839 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); 840 } 841 842 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 843 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 844 pgtable_t pgtable) 845 { 846 struct mm_struct *mm = vma->vm_mm; 847 pmd_t entry; 848 spinlock_t *ptl; 849 850 ptl = pmd_lock(mm, pmd); 851 if (!pmd_none(*pmd)) { 852 if (write) { 853 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 854 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 855 goto out_unlock; 856 } 857 entry = pmd_mkyoung(*pmd); 858 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 859 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 860 update_mmu_cache_pmd(vma, addr, pmd); 861 } 862 863 goto out_unlock; 864 } 865 866 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 867 if (pfn_t_devmap(pfn)) 868 entry = pmd_mkdevmap(entry); 869 if (write) { 870 entry = pmd_mkyoung(pmd_mkdirty(entry)); 871 entry = maybe_pmd_mkwrite(entry, vma); 872 } 873 874 if (pgtable) { 875 pgtable_trans_huge_deposit(mm, pmd, pgtable); 876 mm_inc_nr_ptes(mm); 877 pgtable = NULL; 878 } 879 880 set_pmd_at(mm, addr, pmd, entry); 881 update_mmu_cache_pmd(vma, addr, pmd); 882 883 out_unlock: 884 spin_unlock(ptl); 885 if (pgtable) 886 pte_free(mm, pgtable); 887 } 888 889 /** 890 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn 891 * @vmf: Structure describing the fault 892 * @pfn: pfn to insert 893 * @pgprot: page protection to use 894 * @write: whether it's a write fault 895 * 896 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 897 * also consult the vmf_insert_mixed_prot() documentation when 898 * @pgprot != @vmf->vma->vm_page_prot. 899 * 900 * Return: vm_fault_t value. 901 */ 902 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 903 pgprot_t pgprot, bool write) 904 { 905 unsigned long addr = vmf->address & PMD_MASK; 906 struct vm_area_struct *vma = vmf->vma; 907 pgtable_t pgtable = NULL; 908 909 /* 910 * If we had pmd_special, we could avoid all these restrictions, 911 * but we need to be consistent with PTEs and architectures that 912 * can't support a 'special' bit. 913 */ 914 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 915 !pfn_t_devmap(pfn)); 916 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 917 (VM_PFNMAP|VM_MIXEDMAP)); 918 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 919 920 if (addr < vma->vm_start || addr >= vma->vm_end) 921 return VM_FAULT_SIGBUS; 922 923 if (arch_needs_pgtable_deposit()) { 924 pgtable = pte_alloc_one(vma->vm_mm); 925 if (!pgtable) 926 return VM_FAULT_OOM; 927 } 928 929 track_pfn_insert(vma, &pgprot, pfn); 930 931 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 932 return VM_FAULT_NOPAGE; 933 } 934 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 935 936 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 937 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 938 { 939 if (likely(vma->vm_flags & VM_WRITE)) 940 pud = pud_mkwrite(pud); 941 return pud; 942 } 943 944 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 945 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 946 { 947 struct mm_struct *mm = vma->vm_mm; 948 pud_t entry; 949 spinlock_t *ptl; 950 951 ptl = pud_lock(mm, pud); 952 if (!pud_none(*pud)) { 953 if (write) { 954 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 955 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 956 goto out_unlock; 957 } 958 entry = pud_mkyoung(*pud); 959 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 960 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 961 update_mmu_cache_pud(vma, addr, pud); 962 } 963 goto out_unlock; 964 } 965 966 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 967 if (pfn_t_devmap(pfn)) 968 entry = pud_mkdevmap(entry); 969 if (write) { 970 entry = pud_mkyoung(pud_mkdirty(entry)); 971 entry = maybe_pud_mkwrite(entry, vma); 972 } 973 set_pud_at(mm, addr, pud, entry); 974 update_mmu_cache_pud(vma, addr, pud); 975 976 out_unlock: 977 spin_unlock(ptl); 978 } 979 980 /** 981 * vmf_insert_pfn_pud_prot - insert a pud size pfn 982 * @vmf: Structure describing the fault 983 * @pfn: pfn to insert 984 * @pgprot: page protection to use 985 * @write: whether it's a write fault 986 * 987 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 988 * also consult the vmf_insert_mixed_prot() documentation when 989 * @pgprot != @vmf->vma->vm_page_prot. 990 * 991 * Return: vm_fault_t value. 992 */ 993 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 994 pgprot_t pgprot, bool write) 995 { 996 unsigned long addr = vmf->address & PUD_MASK; 997 struct vm_area_struct *vma = vmf->vma; 998 999 /* 1000 * If we had pud_special, we could avoid all these restrictions, 1001 * but we need to be consistent with PTEs and architectures that 1002 * can't support a 'special' bit. 1003 */ 1004 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1005 !pfn_t_devmap(pfn)); 1006 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1007 (VM_PFNMAP|VM_MIXEDMAP)); 1008 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1009 1010 if (addr < vma->vm_start || addr >= vma->vm_end) 1011 return VM_FAULT_SIGBUS; 1012 1013 track_pfn_insert(vma, &pgprot, pfn); 1014 1015 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 1016 return VM_FAULT_NOPAGE; 1017 } 1018 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 1019 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1020 1021 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1022 pmd_t *pmd, bool write) 1023 { 1024 pmd_t _pmd; 1025 1026 _pmd = pmd_mkyoung(*pmd); 1027 if (write) 1028 _pmd = pmd_mkdirty(_pmd); 1029 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1030 pmd, _pmd, write)) 1031 update_mmu_cache_pmd(vma, addr, pmd); 1032 } 1033 1034 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1035 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1036 { 1037 unsigned long pfn = pmd_pfn(*pmd); 1038 struct mm_struct *mm = vma->vm_mm; 1039 struct page *page; 1040 1041 assert_spin_locked(pmd_lockptr(mm, pmd)); 1042 1043 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1044 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1045 (FOLL_PIN | FOLL_GET))) 1046 return NULL; 1047 1048 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1049 return NULL; 1050 1051 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1052 /* pass */; 1053 else 1054 return NULL; 1055 1056 if (flags & FOLL_TOUCH) 1057 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1058 1059 /* 1060 * device mapped pages can only be returned if the 1061 * caller will manage the page reference count. 1062 */ 1063 if (!(flags & (FOLL_GET | FOLL_PIN))) 1064 return ERR_PTR(-EEXIST); 1065 1066 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1067 *pgmap = get_dev_pagemap(pfn, *pgmap); 1068 if (!*pgmap) 1069 return ERR_PTR(-EFAULT); 1070 page = pfn_to_page(pfn); 1071 if (!try_grab_page(page, flags)) 1072 page = ERR_PTR(-ENOMEM); 1073 1074 return page; 1075 } 1076 1077 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1079 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1080 { 1081 spinlock_t *dst_ptl, *src_ptl; 1082 struct page *src_page; 1083 pmd_t pmd; 1084 pgtable_t pgtable = NULL; 1085 int ret = -ENOMEM; 1086 1087 /* Skip if can be re-fill on fault */ 1088 if (!vma_is_anonymous(dst_vma)) 1089 return 0; 1090 1091 pgtable = pte_alloc_one(dst_mm); 1092 if (unlikely(!pgtable)) 1093 goto out; 1094 1095 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1096 src_ptl = pmd_lockptr(src_mm, src_pmd); 1097 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1098 1099 ret = -EAGAIN; 1100 pmd = *src_pmd; 1101 1102 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1103 if (unlikely(is_swap_pmd(pmd))) { 1104 swp_entry_t entry = pmd_to_swp_entry(pmd); 1105 1106 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1107 if (!is_readable_migration_entry(entry)) { 1108 entry = make_readable_migration_entry( 1109 swp_offset(entry)); 1110 pmd = swp_entry_to_pmd(entry); 1111 if (pmd_swp_soft_dirty(*src_pmd)) 1112 pmd = pmd_swp_mksoft_dirty(pmd); 1113 if (pmd_swp_uffd_wp(*src_pmd)) 1114 pmd = pmd_swp_mkuffd_wp(pmd); 1115 set_pmd_at(src_mm, addr, src_pmd, pmd); 1116 } 1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1118 mm_inc_nr_ptes(dst_mm); 1119 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1120 if (!userfaultfd_wp(dst_vma)) 1121 pmd = pmd_swp_clear_uffd_wp(pmd); 1122 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1123 ret = 0; 1124 goto out_unlock; 1125 } 1126 #endif 1127 1128 if (unlikely(!pmd_trans_huge(pmd))) { 1129 pte_free(dst_mm, pgtable); 1130 goto out_unlock; 1131 } 1132 /* 1133 * When page table lock is held, the huge zero pmd should not be 1134 * under splitting since we don't split the page itself, only pmd to 1135 * a page table. 1136 */ 1137 if (is_huge_zero_pmd(pmd)) { 1138 /* 1139 * get_huge_zero_page() will never allocate a new page here, 1140 * since we already have a zero page to copy. It just takes a 1141 * reference. 1142 */ 1143 mm_get_huge_zero_page(dst_mm); 1144 goto out_zero_page; 1145 } 1146 1147 src_page = pmd_page(pmd); 1148 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1149 1150 get_page(src_page); 1151 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1152 /* Page maybe pinned: split and retry the fault on PTEs. */ 1153 put_page(src_page); 1154 pte_free(dst_mm, pgtable); 1155 spin_unlock(src_ptl); 1156 spin_unlock(dst_ptl); 1157 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1158 return -EAGAIN; 1159 } 1160 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1161 out_zero_page: 1162 mm_inc_nr_ptes(dst_mm); 1163 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1164 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1165 if (!userfaultfd_wp(dst_vma)) 1166 pmd = pmd_clear_uffd_wp(pmd); 1167 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1168 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1169 1170 ret = 0; 1171 out_unlock: 1172 spin_unlock(src_ptl); 1173 spin_unlock(dst_ptl); 1174 out: 1175 return ret; 1176 } 1177 1178 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1179 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1180 pud_t *pud, bool write) 1181 { 1182 pud_t _pud; 1183 1184 _pud = pud_mkyoung(*pud); 1185 if (write) 1186 _pud = pud_mkdirty(_pud); 1187 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1188 pud, _pud, write)) 1189 update_mmu_cache_pud(vma, addr, pud); 1190 } 1191 1192 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1193 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1194 { 1195 unsigned long pfn = pud_pfn(*pud); 1196 struct mm_struct *mm = vma->vm_mm; 1197 struct page *page; 1198 1199 assert_spin_locked(pud_lockptr(mm, pud)); 1200 1201 if (flags & FOLL_WRITE && !pud_write(*pud)) 1202 return NULL; 1203 1204 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1205 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1206 (FOLL_PIN | FOLL_GET))) 1207 return NULL; 1208 1209 if (pud_present(*pud) && pud_devmap(*pud)) 1210 /* pass */; 1211 else 1212 return NULL; 1213 1214 if (flags & FOLL_TOUCH) 1215 touch_pud(vma, addr, pud, flags & FOLL_WRITE); 1216 1217 /* 1218 * device mapped pages can only be returned if the 1219 * caller will manage the page reference count. 1220 * 1221 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1222 */ 1223 if (!(flags & (FOLL_GET | FOLL_PIN))) 1224 return ERR_PTR(-EEXIST); 1225 1226 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1227 *pgmap = get_dev_pagemap(pfn, *pgmap); 1228 if (!*pgmap) 1229 return ERR_PTR(-EFAULT); 1230 page = pfn_to_page(pfn); 1231 if (!try_grab_page(page, flags)) 1232 page = ERR_PTR(-ENOMEM); 1233 1234 return page; 1235 } 1236 1237 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1238 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1239 struct vm_area_struct *vma) 1240 { 1241 spinlock_t *dst_ptl, *src_ptl; 1242 pud_t pud; 1243 int ret; 1244 1245 dst_ptl = pud_lock(dst_mm, dst_pud); 1246 src_ptl = pud_lockptr(src_mm, src_pud); 1247 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1248 1249 ret = -EAGAIN; 1250 pud = *src_pud; 1251 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1252 goto out_unlock; 1253 1254 /* 1255 * When page table lock is held, the huge zero pud should not be 1256 * under splitting since we don't split the page itself, only pud to 1257 * a page table. 1258 */ 1259 if (is_huge_zero_pud(pud)) { 1260 /* No huge zero pud yet */ 1261 } 1262 1263 /* 1264 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1265 * and split if duplicating fails. 1266 */ 1267 pudp_set_wrprotect(src_mm, addr, src_pud); 1268 pud = pud_mkold(pud_wrprotect(pud)); 1269 set_pud_at(dst_mm, addr, dst_pud, pud); 1270 1271 ret = 0; 1272 out_unlock: 1273 spin_unlock(src_ptl); 1274 spin_unlock(dst_ptl); 1275 return ret; 1276 } 1277 1278 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1279 { 1280 bool write = vmf->flags & FAULT_FLAG_WRITE; 1281 1282 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1283 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1284 goto unlock; 1285 1286 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1287 unlock: 1288 spin_unlock(vmf->ptl); 1289 } 1290 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1291 1292 void huge_pmd_set_accessed(struct vm_fault *vmf) 1293 { 1294 bool write = vmf->flags & FAULT_FLAG_WRITE; 1295 1296 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1297 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1298 goto unlock; 1299 1300 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1301 1302 unlock: 1303 spin_unlock(vmf->ptl); 1304 } 1305 1306 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1307 { 1308 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1309 struct vm_area_struct *vma = vmf->vma; 1310 struct page *page; 1311 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1312 pmd_t orig_pmd = vmf->orig_pmd; 1313 1314 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1315 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1316 1317 VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE)); 1318 VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE)); 1319 1320 if (is_huge_zero_pmd(orig_pmd)) 1321 goto fallback; 1322 1323 spin_lock(vmf->ptl); 1324 1325 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1326 spin_unlock(vmf->ptl); 1327 return 0; 1328 } 1329 1330 page = pmd_page(orig_pmd); 1331 VM_BUG_ON_PAGE(!PageHead(page), page); 1332 1333 /* Early check when only holding the PT lock. */ 1334 if (PageAnonExclusive(page)) 1335 goto reuse; 1336 1337 if (!trylock_page(page)) { 1338 get_page(page); 1339 spin_unlock(vmf->ptl); 1340 lock_page(page); 1341 spin_lock(vmf->ptl); 1342 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1343 spin_unlock(vmf->ptl); 1344 unlock_page(page); 1345 put_page(page); 1346 return 0; 1347 } 1348 put_page(page); 1349 } 1350 1351 /* Recheck after temporarily dropping the PT lock. */ 1352 if (PageAnonExclusive(page)) { 1353 unlock_page(page); 1354 goto reuse; 1355 } 1356 1357 /* 1358 * See do_wp_page(): we can only reuse the page exclusively if there are 1359 * no additional references. Note that we always drain the LRU 1360 * pagevecs immediately after adding a THP. 1361 */ 1362 if (page_count(page) > 1 + PageSwapCache(page) * thp_nr_pages(page)) 1363 goto unlock_fallback; 1364 if (PageSwapCache(page)) 1365 try_to_free_swap(page); 1366 if (page_count(page) == 1) { 1367 pmd_t entry; 1368 1369 page_move_anon_rmap(page, vma); 1370 unlock_page(page); 1371 reuse: 1372 if (unlikely(unshare)) { 1373 spin_unlock(vmf->ptl); 1374 return 0; 1375 } 1376 entry = pmd_mkyoung(orig_pmd); 1377 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1378 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1379 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1380 spin_unlock(vmf->ptl); 1381 return VM_FAULT_WRITE; 1382 } 1383 1384 unlock_fallback: 1385 unlock_page(page); 1386 spin_unlock(vmf->ptl); 1387 fallback: 1388 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1389 return VM_FAULT_FALLBACK; 1390 } 1391 1392 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1393 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1394 struct vm_area_struct *vma, 1395 unsigned int flags) 1396 { 1397 /* If the pmd is writable, we can write to the page. */ 1398 if (pmd_write(pmd)) 1399 return true; 1400 1401 /* Maybe FOLL_FORCE is set to override it? */ 1402 if (!(flags & FOLL_FORCE)) 1403 return false; 1404 1405 /* But FOLL_FORCE has no effect on shared mappings */ 1406 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1407 return false; 1408 1409 /* ... or read-only private ones */ 1410 if (!(vma->vm_flags & VM_MAYWRITE)) 1411 return false; 1412 1413 /* ... or already writable ones that just need to take a write fault */ 1414 if (vma->vm_flags & VM_WRITE) 1415 return false; 1416 1417 /* 1418 * See can_change_pte_writable(): we broke COW and could map the page 1419 * writable if we have an exclusive anonymous page ... 1420 */ 1421 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1422 return false; 1423 1424 /* ... and a write-fault isn't required for other reasons. */ 1425 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1426 return false; 1427 return !userfaultfd_huge_pmd_wp(vma, pmd); 1428 } 1429 1430 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1431 unsigned long addr, 1432 pmd_t *pmd, 1433 unsigned int flags) 1434 { 1435 struct mm_struct *mm = vma->vm_mm; 1436 struct page *page; 1437 1438 assert_spin_locked(pmd_lockptr(mm, pmd)); 1439 1440 page = pmd_page(*pmd); 1441 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1442 1443 if ((flags & FOLL_WRITE) && 1444 !can_follow_write_pmd(*pmd, page, vma, flags)) 1445 return NULL; 1446 1447 /* Avoid dumping huge zero page */ 1448 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1449 return ERR_PTR(-EFAULT); 1450 1451 /* Full NUMA hinting faults to serialise migration in fault paths */ 1452 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1453 return NULL; 1454 1455 if (!pmd_write(*pmd) && gup_must_unshare(flags, page)) 1456 return ERR_PTR(-EMLINK); 1457 1458 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1459 !PageAnonExclusive(page), page); 1460 1461 if (!try_grab_page(page, flags)) 1462 return ERR_PTR(-ENOMEM); 1463 1464 if (flags & FOLL_TOUCH) 1465 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1466 1467 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1468 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1469 1470 return page; 1471 } 1472 1473 /* NUMA hinting page fault entry point for trans huge pmds */ 1474 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1475 { 1476 struct vm_area_struct *vma = vmf->vma; 1477 pmd_t oldpmd = vmf->orig_pmd; 1478 pmd_t pmd; 1479 struct page *page; 1480 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1481 int page_nid = NUMA_NO_NODE; 1482 int target_nid, last_cpupid = -1; 1483 bool migrated = false; 1484 bool was_writable = pmd_savedwrite(oldpmd); 1485 int flags = 0; 1486 1487 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1488 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1489 spin_unlock(vmf->ptl); 1490 goto out; 1491 } 1492 1493 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1494 page = vm_normal_page_pmd(vma, haddr, pmd); 1495 if (!page) 1496 goto out_map; 1497 1498 /* See similar comment in do_numa_page for explanation */ 1499 if (!was_writable) 1500 flags |= TNF_NO_GROUP; 1501 1502 page_nid = page_to_nid(page); 1503 last_cpupid = page_cpupid_last(page); 1504 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1505 &flags); 1506 1507 if (target_nid == NUMA_NO_NODE) { 1508 put_page(page); 1509 goto out_map; 1510 } 1511 1512 spin_unlock(vmf->ptl); 1513 1514 migrated = migrate_misplaced_page(page, vma, target_nid); 1515 if (migrated) { 1516 flags |= TNF_MIGRATED; 1517 page_nid = target_nid; 1518 } else { 1519 flags |= TNF_MIGRATE_FAIL; 1520 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1521 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1522 spin_unlock(vmf->ptl); 1523 goto out; 1524 } 1525 goto out_map; 1526 } 1527 1528 out: 1529 if (page_nid != NUMA_NO_NODE) 1530 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1531 flags); 1532 1533 return 0; 1534 1535 out_map: 1536 /* Restore the PMD */ 1537 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1538 pmd = pmd_mkyoung(pmd); 1539 if (was_writable) 1540 pmd = pmd_mkwrite(pmd); 1541 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1542 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1543 spin_unlock(vmf->ptl); 1544 goto out; 1545 } 1546 1547 /* 1548 * Return true if we do MADV_FREE successfully on entire pmd page. 1549 * Otherwise, return false. 1550 */ 1551 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1552 pmd_t *pmd, unsigned long addr, unsigned long next) 1553 { 1554 spinlock_t *ptl; 1555 pmd_t orig_pmd; 1556 struct page *page; 1557 struct mm_struct *mm = tlb->mm; 1558 bool ret = false; 1559 1560 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1561 1562 ptl = pmd_trans_huge_lock(pmd, vma); 1563 if (!ptl) 1564 goto out_unlocked; 1565 1566 orig_pmd = *pmd; 1567 if (is_huge_zero_pmd(orig_pmd)) 1568 goto out; 1569 1570 if (unlikely(!pmd_present(orig_pmd))) { 1571 VM_BUG_ON(thp_migration_supported() && 1572 !is_pmd_migration_entry(orig_pmd)); 1573 goto out; 1574 } 1575 1576 page = pmd_page(orig_pmd); 1577 /* 1578 * If other processes are mapping this page, we couldn't discard 1579 * the page unless they all do MADV_FREE so let's skip the page. 1580 */ 1581 if (total_mapcount(page) != 1) 1582 goto out; 1583 1584 if (!trylock_page(page)) 1585 goto out; 1586 1587 /* 1588 * If user want to discard part-pages of THP, split it so MADV_FREE 1589 * will deactivate only them. 1590 */ 1591 if (next - addr != HPAGE_PMD_SIZE) { 1592 get_page(page); 1593 spin_unlock(ptl); 1594 split_huge_page(page); 1595 unlock_page(page); 1596 put_page(page); 1597 goto out_unlocked; 1598 } 1599 1600 if (PageDirty(page)) 1601 ClearPageDirty(page); 1602 unlock_page(page); 1603 1604 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1605 pmdp_invalidate(vma, addr, pmd); 1606 orig_pmd = pmd_mkold(orig_pmd); 1607 orig_pmd = pmd_mkclean(orig_pmd); 1608 1609 set_pmd_at(mm, addr, pmd, orig_pmd); 1610 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1611 } 1612 1613 mark_page_lazyfree(page); 1614 ret = true; 1615 out: 1616 spin_unlock(ptl); 1617 out_unlocked: 1618 return ret; 1619 } 1620 1621 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1622 { 1623 pgtable_t pgtable; 1624 1625 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1626 pte_free(mm, pgtable); 1627 mm_dec_nr_ptes(mm); 1628 } 1629 1630 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1631 pmd_t *pmd, unsigned long addr) 1632 { 1633 pmd_t orig_pmd; 1634 spinlock_t *ptl; 1635 1636 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1637 1638 ptl = __pmd_trans_huge_lock(pmd, vma); 1639 if (!ptl) 1640 return 0; 1641 /* 1642 * For architectures like ppc64 we look at deposited pgtable 1643 * when calling pmdp_huge_get_and_clear. So do the 1644 * pgtable_trans_huge_withdraw after finishing pmdp related 1645 * operations. 1646 */ 1647 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1648 tlb->fullmm); 1649 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1650 if (vma_is_special_huge(vma)) { 1651 if (arch_needs_pgtable_deposit()) 1652 zap_deposited_table(tlb->mm, pmd); 1653 spin_unlock(ptl); 1654 } else if (is_huge_zero_pmd(orig_pmd)) { 1655 zap_deposited_table(tlb->mm, pmd); 1656 spin_unlock(ptl); 1657 } else { 1658 struct page *page = NULL; 1659 int flush_needed = 1; 1660 1661 if (pmd_present(orig_pmd)) { 1662 page = pmd_page(orig_pmd); 1663 page_remove_rmap(page, vma, true); 1664 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1665 VM_BUG_ON_PAGE(!PageHead(page), page); 1666 } else if (thp_migration_supported()) { 1667 swp_entry_t entry; 1668 1669 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1670 entry = pmd_to_swp_entry(orig_pmd); 1671 page = pfn_swap_entry_to_page(entry); 1672 flush_needed = 0; 1673 } else 1674 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1675 1676 if (PageAnon(page)) { 1677 zap_deposited_table(tlb->mm, pmd); 1678 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1679 } else { 1680 if (arch_needs_pgtable_deposit()) 1681 zap_deposited_table(tlb->mm, pmd); 1682 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1683 } 1684 1685 spin_unlock(ptl); 1686 if (flush_needed) 1687 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1688 } 1689 return 1; 1690 } 1691 1692 #ifndef pmd_move_must_withdraw 1693 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1694 spinlock_t *old_pmd_ptl, 1695 struct vm_area_struct *vma) 1696 { 1697 /* 1698 * With split pmd lock we also need to move preallocated 1699 * PTE page table if new_pmd is on different PMD page table. 1700 * 1701 * We also don't deposit and withdraw tables for file pages. 1702 */ 1703 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1704 } 1705 #endif 1706 1707 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1708 { 1709 #ifdef CONFIG_MEM_SOFT_DIRTY 1710 if (unlikely(is_pmd_migration_entry(pmd))) 1711 pmd = pmd_swp_mksoft_dirty(pmd); 1712 else if (pmd_present(pmd)) 1713 pmd = pmd_mksoft_dirty(pmd); 1714 #endif 1715 return pmd; 1716 } 1717 1718 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1719 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1720 { 1721 spinlock_t *old_ptl, *new_ptl; 1722 pmd_t pmd; 1723 struct mm_struct *mm = vma->vm_mm; 1724 bool force_flush = false; 1725 1726 /* 1727 * The destination pmd shouldn't be established, free_pgtables() 1728 * should have release it. 1729 */ 1730 if (WARN_ON(!pmd_none(*new_pmd))) { 1731 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1732 return false; 1733 } 1734 1735 /* 1736 * We don't have to worry about the ordering of src and dst 1737 * ptlocks because exclusive mmap_lock prevents deadlock. 1738 */ 1739 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1740 if (old_ptl) { 1741 new_ptl = pmd_lockptr(mm, new_pmd); 1742 if (new_ptl != old_ptl) 1743 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1744 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1745 if (pmd_present(pmd)) 1746 force_flush = true; 1747 VM_BUG_ON(!pmd_none(*new_pmd)); 1748 1749 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1750 pgtable_t pgtable; 1751 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1752 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1753 } 1754 pmd = move_soft_dirty_pmd(pmd); 1755 set_pmd_at(mm, new_addr, new_pmd, pmd); 1756 if (force_flush) 1757 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1758 if (new_ptl != old_ptl) 1759 spin_unlock(new_ptl); 1760 spin_unlock(old_ptl); 1761 return true; 1762 } 1763 return false; 1764 } 1765 1766 /* 1767 * Returns 1768 * - 0 if PMD could not be locked 1769 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1770 * or if prot_numa but THP migration is not supported 1771 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1772 */ 1773 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1774 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1775 unsigned long cp_flags) 1776 { 1777 struct mm_struct *mm = vma->vm_mm; 1778 spinlock_t *ptl; 1779 pmd_t oldpmd, entry; 1780 bool preserve_write; 1781 int ret; 1782 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1783 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1784 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1785 1786 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1787 1788 if (prot_numa && !thp_migration_supported()) 1789 return 1; 1790 1791 ptl = __pmd_trans_huge_lock(pmd, vma); 1792 if (!ptl) 1793 return 0; 1794 1795 preserve_write = prot_numa && pmd_write(*pmd); 1796 ret = 1; 1797 1798 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1799 if (is_swap_pmd(*pmd)) { 1800 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1801 struct page *page = pfn_swap_entry_to_page(entry); 1802 1803 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1804 if (is_writable_migration_entry(entry)) { 1805 pmd_t newpmd; 1806 /* 1807 * A protection check is difficult so 1808 * just be safe and disable write 1809 */ 1810 if (PageAnon(page)) 1811 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1812 else 1813 entry = make_readable_migration_entry(swp_offset(entry)); 1814 newpmd = swp_entry_to_pmd(entry); 1815 if (pmd_swp_soft_dirty(*pmd)) 1816 newpmd = pmd_swp_mksoft_dirty(newpmd); 1817 if (pmd_swp_uffd_wp(*pmd)) 1818 newpmd = pmd_swp_mkuffd_wp(newpmd); 1819 set_pmd_at(mm, addr, pmd, newpmd); 1820 } 1821 goto unlock; 1822 } 1823 #endif 1824 1825 if (prot_numa) { 1826 struct page *page; 1827 /* 1828 * Avoid trapping faults against the zero page. The read-only 1829 * data is likely to be read-cached on the local CPU and 1830 * local/remote hits to the zero page are not interesting. 1831 */ 1832 if (is_huge_zero_pmd(*pmd)) 1833 goto unlock; 1834 1835 if (pmd_protnone(*pmd)) 1836 goto unlock; 1837 1838 page = pmd_page(*pmd); 1839 /* 1840 * Skip scanning top tier node if normal numa 1841 * balancing is disabled 1842 */ 1843 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1844 node_is_toptier(page_to_nid(page))) 1845 goto unlock; 1846 } 1847 /* 1848 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1849 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1850 * which is also under mmap_read_lock(mm): 1851 * 1852 * CPU0: CPU1: 1853 * change_huge_pmd(prot_numa=1) 1854 * pmdp_huge_get_and_clear_notify() 1855 * madvise_dontneed() 1856 * zap_pmd_range() 1857 * pmd_trans_huge(*pmd) == 0 (without ptl) 1858 * // skip the pmd 1859 * set_pmd_at(); 1860 * // pmd is re-established 1861 * 1862 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1863 * which may break userspace. 1864 * 1865 * pmdp_invalidate_ad() is required to make sure we don't miss 1866 * dirty/young flags set by hardware. 1867 */ 1868 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1869 1870 entry = pmd_modify(oldpmd, newprot); 1871 if (preserve_write) 1872 entry = pmd_mk_savedwrite(entry); 1873 if (uffd_wp) { 1874 entry = pmd_wrprotect(entry); 1875 entry = pmd_mkuffd_wp(entry); 1876 } else if (uffd_wp_resolve) { 1877 /* 1878 * Leave the write bit to be handled by PF interrupt 1879 * handler, then things like COW could be properly 1880 * handled. 1881 */ 1882 entry = pmd_clear_uffd_wp(entry); 1883 } 1884 ret = HPAGE_PMD_NR; 1885 set_pmd_at(mm, addr, pmd, entry); 1886 1887 if (huge_pmd_needs_flush(oldpmd, entry)) 1888 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1889 1890 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1891 unlock: 1892 spin_unlock(ptl); 1893 return ret; 1894 } 1895 1896 /* 1897 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1898 * 1899 * Note that if it returns page table lock pointer, this routine returns without 1900 * unlocking page table lock. So callers must unlock it. 1901 */ 1902 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1903 { 1904 spinlock_t *ptl; 1905 ptl = pmd_lock(vma->vm_mm, pmd); 1906 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1907 pmd_devmap(*pmd))) 1908 return ptl; 1909 spin_unlock(ptl); 1910 return NULL; 1911 } 1912 1913 /* 1914 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1915 * 1916 * Note that if it returns page table lock pointer, this routine returns without 1917 * unlocking page table lock. So callers must unlock it. 1918 */ 1919 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1920 { 1921 spinlock_t *ptl; 1922 1923 ptl = pud_lock(vma->vm_mm, pud); 1924 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1925 return ptl; 1926 spin_unlock(ptl); 1927 return NULL; 1928 } 1929 1930 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1931 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1932 pud_t *pud, unsigned long addr) 1933 { 1934 spinlock_t *ptl; 1935 1936 ptl = __pud_trans_huge_lock(pud, vma); 1937 if (!ptl) 1938 return 0; 1939 1940 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1941 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1942 if (vma_is_special_huge(vma)) { 1943 spin_unlock(ptl); 1944 /* No zero page support yet */ 1945 } else { 1946 /* No support for anonymous PUD pages yet */ 1947 BUG(); 1948 } 1949 return 1; 1950 } 1951 1952 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1953 unsigned long haddr) 1954 { 1955 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1956 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1957 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1958 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1959 1960 count_vm_event(THP_SPLIT_PUD); 1961 1962 pudp_huge_clear_flush_notify(vma, haddr, pud); 1963 } 1964 1965 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1966 unsigned long address) 1967 { 1968 spinlock_t *ptl; 1969 struct mmu_notifier_range range; 1970 1971 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1972 address & HPAGE_PUD_MASK, 1973 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1974 mmu_notifier_invalidate_range_start(&range); 1975 ptl = pud_lock(vma->vm_mm, pud); 1976 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1977 goto out; 1978 __split_huge_pud_locked(vma, pud, range.start); 1979 1980 out: 1981 spin_unlock(ptl); 1982 /* 1983 * No need to double call mmu_notifier->invalidate_range() callback as 1984 * the above pudp_huge_clear_flush_notify() did already call it. 1985 */ 1986 mmu_notifier_invalidate_range_only_end(&range); 1987 } 1988 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1989 1990 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 1991 unsigned long haddr, pmd_t *pmd) 1992 { 1993 struct mm_struct *mm = vma->vm_mm; 1994 pgtable_t pgtable; 1995 pmd_t _pmd; 1996 int i; 1997 1998 /* 1999 * Leave pmd empty until pte is filled note that it is fine to delay 2000 * notification until mmu_notifier_invalidate_range_end() as we are 2001 * replacing a zero pmd write protected page with a zero pte write 2002 * protected page. 2003 * 2004 * See Documentation/mm/mmu_notifier.rst 2005 */ 2006 pmdp_huge_clear_flush(vma, haddr, pmd); 2007 2008 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2009 pmd_populate(mm, &_pmd, pgtable); 2010 2011 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2012 pte_t *pte, entry; 2013 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2014 entry = pte_mkspecial(entry); 2015 pte = pte_offset_map(&_pmd, haddr); 2016 VM_BUG_ON(!pte_none(*pte)); 2017 set_pte_at(mm, haddr, pte, entry); 2018 pte_unmap(pte); 2019 } 2020 smp_wmb(); /* make pte visible before pmd */ 2021 pmd_populate(mm, pmd, pgtable); 2022 } 2023 2024 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2025 unsigned long haddr, bool freeze) 2026 { 2027 struct mm_struct *mm = vma->vm_mm; 2028 struct page *page; 2029 pgtable_t pgtable; 2030 pmd_t old_pmd, _pmd; 2031 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2032 bool anon_exclusive = false; 2033 unsigned long addr; 2034 int i; 2035 2036 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2037 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2038 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2039 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2040 && !pmd_devmap(*pmd)); 2041 2042 count_vm_event(THP_SPLIT_PMD); 2043 2044 if (!vma_is_anonymous(vma)) { 2045 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2046 /* 2047 * We are going to unmap this huge page. So 2048 * just go ahead and zap it 2049 */ 2050 if (arch_needs_pgtable_deposit()) 2051 zap_deposited_table(mm, pmd); 2052 if (vma_is_special_huge(vma)) 2053 return; 2054 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2055 swp_entry_t entry; 2056 2057 entry = pmd_to_swp_entry(old_pmd); 2058 page = pfn_swap_entry_to_page(entry); 2059 } else { 2060 page = pmd_page(old_pmd); 2061 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2062 set_page_dirty(page); 2063 if (!PageReferenced(page) && pmd_young(old_pmd)) 2064 SetPageReferenced(page); 2065 page_remove_rmap(page, vma, true); 2066 put_page(page); 2067 } 2068 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2069 return; 2070 } 2071 2072 if (is_huge_zero_pmd(*pmd)) { 2073 /* 2074 * FIXME: Do we want to invalidate secondary mmu by calling 2075 * mmu_notifier_invalidate_range() see comments below inside 2076 * __split_huge_pmd() ? 2077 * 2078 * We are going from a zero huge page write protected to zero 2079 * small page also write protected so it does not seems useful 2080 * to invalidate secondary mmu at this time. 2081 */ 2082 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2083 } 2084 2085 /* 2086 * Up to this point the pmd is present and huge and userland has the 2087 * whole access to the hugepage during the split (which happens in 2088 * place). If we overwrite the pmd with the not-huge version pointing 2089 * to the pte here (which of course we could if all CPUs were bug 2090 * free), userland could trigger a small page size TLB miss on the 2091 * small sized TLB while the hugepage TLB entry is still established in 2092 * the huge TLB. Some CPU doesn't like that. 2093 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2094 * 383 on page 105. Intel should be safe but is also warns that it's 2095 * only safe if the permission and cache attributes of the two entries 2096 * loaded in the two TLB is identical (which should be the case here). 2097 * But it is generally safer to never allow small and huge TLB entries 2098 * for the same virtual address to be loaded simultaneously. So instead 2099 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2100 * current pmd notpresent (atomically because here the pmd_trans_huge 2101 * must remain set at all times on the pmd until the split is complete 2102 * for this pmd), then we flush the SMP TLB and finally we write the 2103 * non-huge version of the pmd entry with pmd_populate. 2104 */ 2105 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2106 2107 pmd_migration = is_pmd_migration_entry(old_pmd); 2108 if (unlikely(pmd_migration)) { 2109 swp_entry_t entry; 2110 2111 entry = pmd_to_swp_entry(old_pmd); 2112 page = pfn_swap_entry_to_page(entry); 2113 write = is_writable_migration_entry(entry); 2114 if (PageAnon(page)) 2115 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2116 young = false; 2117 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2118 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2119 } else { 2120 page = pmd_page(old_pmd); 2121 if (pmd_dirty(old_pmd)) 2122 SetPageDirty(page); 2123 write = pmd_write(old_pmd); 2124 young = pmd_young(old_pmd); 2125 soft_dirty = pmd_soft_dirty(old_pmd); 2126 uffd_wp = pmd_uffd_wp(old_pmd); 2127 2128 VM_BUG_ON_PAGE(!page_count(page), page); 2129 page_ref_add(page, HPAGE_PMD_NR - 1); 2130 2131 /* 2132 * Without "freeze", we'll simply split the PMD, propagating the 2133 * PageAnonExclusive() flag for each PTE by setting it for 2134 * each subpage -- no need to (temporarily) clear. 2135 * 2136 * With "freeze" we want to replace mapped pages by 2137 * migration entries right away. This is only possible if we 2138 * managed to clear PageAnonExclusive() -- see 2139 * set_pmd_migration_entry(). 2140 * 2141 * In case we cannot clear PageAnonExclusive(), split the PMD 2142 * only and let try_to_migrate_one() fail later. 2143 */ 2144 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2145 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2146 freeze = false; 2147 } 2148 2149 /* 2150 * Withdraw the table only after we mark the pmd entry invalid. 2151 * This's critical for some architectures (Power). 2152 */ 2153 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2154 pmd_populate(mm, &_pmd, pgtable); 2155 2156 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2157 pte_t entry, *pte; 2158 /* 2159 * Note that NUMA hinting access restrictions are not 2160 * transferred to avoid any possibility of altering 2161 * permissions across VMAs. 2162 */ 2163 if (freeze || pmd_migration) { 2164 swp_entry_t swp_entry; 2165 if (write) 2166 swp_entry = make_writable_migration_entry( 2167 page_to_pfn(page + i)); 2168 else if (anon_exclusive) 2169 swp_entry = make_readable_exclusive_migration_entry( 2170 page_to_pfn(page + i)); 2171 else 2172 swp_entry = make_readable_migration_entry( 2173 page_to_pfn(page + i)); 2174 entry = swp_entry_to_pte(swp_entry); 2175 if (soft_dirty) 2176 entry = pte_swp_mksoft_dirty(entry); 2177 if (uffd_wp) 2178 entry = pte_swp_mkuffd_wp(entry); 2179 } else { 2180 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2181 entry = maybe_mkwrite(entry, vma); 2182 if (anon_exclusive) 2183 SetPageAnonExclusive(page + i); 2184 if (!write) 2185 entry = pte_wrprotect(entry); 2186 if (!young) 2187 entry = pte_mkold(entry); 2188 if (soft_dirty) 2189 entry = pte_mksoft_dirty(entry); 2190 if (uffd_wp) 2191 entry = pte_mkuffd_wp(entry); 2192 } 2193 pte = pte_offset_map(&_pmd, addr); 2194 BUG_ON(!pte_none(*pte)); 2195 set_pte_at(mm, addr, pte, entry); 2196 if (!pmd_migration) 2197 atomic_inc(&page[i]._mapcount); 2198 pte_unmap(pte); 2199 } 2200 2201 if (!pmd_migration) { 2202 /* 2203 * Set PG_double_map before dropping compound_mapcount to avoid 2204 * false-negative page_mapped(). 2205 */ 2206 if (compound_mapcount(page) > 1 && 2207 !TestSetPageDoubleMap(page)) { 2208 for (i = 0; i < HPAGE_PMD_NR; i++) 2209 atomic_inc(&page[i]._mapcount); 2210 } 2211 2212 lock_page_memcg(page); 2213 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2214 /* Last compound_mapcount is gone. */ 2215 __mod_lruvec_page_state(page, NR_ANON_THPS, 2216 -HPAGE_PMD_NR); 2217 if (TestClearPageDoubleMap(page)) { 2218 /* No need in mapcount reference anymore */ 2219 for (i = 0; i < HPAGE_PMD_NR; i++) 2220 atomic_dec(&page[i]._mapcount); 2221 } 2222 } 2223 unlock_page_memcg(page); 2224 2225 /* Above is effectively page_remove_rmap(page, vma, true) */ 2226 munlock_vma_page(page, vma, true); 2227 } 2228 2229 smp_wmb(); /* make pte visible before pmd */ 2230 pmd_populate(mm, pmd, pgtable); 2231 2232 if (freeze) { 2233 for (i = 0; i < HPAGE_PMD_NR; i++) { 2234 page_remove_rmap(page + i, vma, false); 2235 put_page(page + i); 2236 } 2237 } 2238 } 2239 2240 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2241 unsigned long address, bool freeze, struct folio *folio) 2242 { 2243 spinlock_t *ptl; 2244 struct mmu_notifier_range range; 2245 2246 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2247 address & HPAGE_PMD_MASK, 2248 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2249 mmu_notifier_invalidate_range_start(&range); 2250 ptl = pmd_lock(vma->vm_mm, pmd); 2251 2252 /* 2253 * If caller asks to setup a migration entry, we need a folio to check 2254 * pmd against. Otherwise we can end up replacing wrong folio. 2255 */ 2256 VM_BUG_ON(freeze && !folio); 2257 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2258 2259 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2260 is_pmd_migration_entry(*pmd)) { 2261 /* 2262 * It's safe to call pmd_page when folio is set because it's 2263 * guaranteed that pmd is present. 2264 */ 2265 if (folio && folio != page_folio(pmd_page(*pmd))) 2266 goto out; 2267 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2268 } 2269 2270 out: 2271 spin_unlock(ptl); 2272 /* 2273 * No need to double call mmu_notifier->invalidate_range() callback. 2274 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2275 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2276 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2277 * fault will trigger a flush_notify before pointing to a new page 2278 * (it is fine if the secondary mmu keeps pointing to the old zero 2279 * page in the meantime) 2280 * 3) Split a huge pmd into pte pointing to the same page. No need 2281 * to invalidate secondary tlb entry they are all still valid. 2282 * any further changes to individual pte will notify. So no need 2283 * to call mmu_notifier->invalidate_range() 2284 */ 2285 mmu_notifier_invalidate_range_only_end(&range); 2286 } 2287 2288 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2289 bool freeze, struct folio *folio) 2290 { 2291 pgd_t *pgd; 2292 p4d_t *p4d; 2293 pud_t *pud; 2294 pmd_t *pmd; 2295 2296 pgd = pgd_offset(vma->vm_mm, address); 2297 if (!pgd_present(*pgd)) 2298 return; 2299 2300 p4d = p4d_offset(pgd, address); 2301 if (!p4d_present(*p4d)) 2302 return; 2303 2304 pud = pud_offset(p4d, address); 2305 if (!pud_present(*pud)) 2306 return; 2307 2308 pmd = pmd_offset(pud, address); 2309 2310 __split_huge_pmd(vma, pmd, address, freeze, folio); 2311 } 2312 2313 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2314 { 2315 /* 2316 * If the new address isn't hpage aligned and it could previously 2317 * contain an hugepage: check if we need to split an huge pmd. 2318 */ 2319 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2320 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2321 ALIGN(address, HPAGE_PMD_SIZE))) 2322 split_huge_pmd_address(vma, address, false, NULL); 2323 } 2324 2325 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2326 unsigned long start, 2327 unsigned long end, 2328 long adjust_next) 2329 { 2330 /* Check if we need to split start first. */ 2331 split_huge_pmd_if_needed(vma, start); 2332 2333 /* Check if we need to split end next. */ 2334 split_huge_pmd_if_needed(vma, end); 2335 2336 /* 2337 * If we're also updating the vma->vm_next->vm_start, 2338 * check if we need to split it. 2339 */ 2340 if (adjust_next > 0) { 2341 struct vm_area_struct *next = vma->vm_next; 2342 unsigned long nstart = next->vm_start; 2343 nstart += adjust_next; 2344 split_huge_pmd_if_needed(next, nstart); 2345 } 2346 } 2347 2348 static void unmap_page(struct page *page) 2349 { 2350 struct folio *folio = page_folio(page); 2351 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2352 TTU_SYNC; 2353 2354 VM_BUG_ON_PAGE(!PageHead(page), page); 2355 2356 /* 2357 * Anon pages need migration entries to preserve them, but file 2358 * pages can simply be left unmapped, then faulted back on demand. 2359 * If that is ever changed (perhaps for mlock), update remap_page(). 2360 */ 2361 if (folio_test_anon(folio)) 2362 try_to_migrate(folio, ttu_flags); 2363 else 2364 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2365 } 2366 2367 static void remap_page(struct folio *folio, unsigned long nr) 2368 { 2369 int i = 0; 2370 2371 /* If unmap_page() uses try_to_migrate() on file, remove this check */ 2372 if (!folio_test_anon(folio)) 2373 return; 2374 for (;;) { 2375 remove_migration_ptes(folio, folio, true); 2376 i += folio_nr_pages(folio); 2377 if (i >= nr) 2378 break; 2379 folio = folio_next(folio); 2380 } 2381 } 2382 2383 static void lru_add_page_tail(struct page *head, struct page *tail, 2384 struct lruvec *lruvec, struct list_head *list) 2385 { 2386 VM_BUG_ON_PAGE(!PageHead(head), head); 2387 VM_BUG_ON_PAGE(PageCompound(tail), head); 2388 VM_BUG_ON_PAGE(PageLRU(tail), head); 2389 lockdep_assert_held(&lruvec->lru_lock); 2390 2391 if (list) { 2392 /* page reclaim is reclaiming a huge page */ 2393 VM_WARN_ON(PageLRU(head)); 2394 get_page(tail); 2395 list_add_tail(&tail->lru, list); 2396 } else { 2397 /* head is still on lru (and we have it frozen) */ 2398 VM_WARN_ON(!PageLRU(head)); 2399 if (PageUnevictable(tail)) 2400 tail->mlock_count = 0; 2401 else 2402 list_add_tail(&tail->lru, &head->lru); 2403 SetPageLRU(tail); 2404 } 2405 } 2406 2407 static void __split_huge_page_tail(struct page *head, int tail, 2408 struct lruvec *lruvec, struct list_head *list) 2409 { 2410 struct page *page_tail = head + tail; 2411 2412 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2413 2414 /* 2415 * Clone page flags before unfreezing refcount. 2416 * 2417 * After successful get_page_unless_zero() might follow flags change, 2418 * for example lock_page() which set PG_waiters. 2419 * 2420 * Note that for mapped sub-pages of an anonymous THP, 2421 * PG_anon_exclusive has been cleared in unmap_page() and is stored in 2422 * the migration entry instead from where remap_page() will restore it. 2423 * We can still have PG_anon_exclusive set on effectively unmapped and 2424 * unreferenced sub-pages of an anonymous THP: we can simply drop 2425 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2426 */ 2427 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2428 page_tail->flags |= (head->flags & 2429 ((1L << PG_referenced) | 2430 (1L << PG_swapbacked) | 2431 (1L << PG_swapcache) | 2432 (1L << PG_mlocked) | 2433 (1L << PG_uptodate) | 2434 (1L << PG_active) | 2435 (1L << PG_workingset) | 2436 (1L << PG_locked) | 2437 (1L << PG_unevictable) | 2438 #ifdef CONFIG_64BIT 2439 (1L << PG_arch_2) | 2440 #endif 2441 (1L << PG_dirty))); 2442 2443 /* ->mapping in first tail page is compound_mapcount */ 2444 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2445 page_tail); 2446 page_tail->mapping = head->mapping; 2447 page_tail->index = head->index + tail; 2448 page_tail->private = 0; 2449 2450 /* Page flags must be visible before we make the page non-compound. */ 2451 smp_wmb(); 2452 2453 /* 2454 * Clear PageTail before unfreezing page refcount. 2455 * 2456 * After successful get_page_unless_zero() might follow put_page() 2457 * which needs correct compound_head(). 2458 */ 2459 clear_compound_head(page_tail); 2460 2461 /* Finally unfreeze refcount. Additional reference from page cache. */ 2462 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2463 PageSwapCache(head))); 2464 2465 if (page_is_young(head)) 2466 set_page_young(page_tail); 2467 if (page_is_idle(head)) 2468 set_page_idle(page_tail); 2469 2470 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2471 2472 /* 2473 * always add to the tail because some iterators expect new 2474 * pages to show after the currently processed elements - e.g. 2475 * migrate_pages 2476 */ 2477 lru_add_page_tail(head, page_tail, lruvec, list); 2478 } 2479 2480 static void __split_huge_page(struct page *page, struct list_head *list, 2481 pgoff_t end) 2482 { 2483 struct folio *folio = page_folio(page); 2484 struct page *head = &folio->page; 2485 struct lruvec *lruvec; 2486 struct address_space *swap_cache = NULL; 2487 unsigned long offset = 0; 2488 unsigned int nr = thp_nr_pages(head); 2489 int i; 2490 2491 /* complete memcg works before add pages to LRU */ 2492 split_page_memcg(head, nr); 2493 2494 if (PageAnon(head) && PageSwapCache(head)) { 2495 swp_entry_t entry = { .val = page_private(head) }; 2496 2497 offset = swp_offset(entry); 2498 swap_cache = swap_address_space(entry); 2499 xa_lock(&swap_cache->i_pages); 2500 } 2501 2502 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2503 lruvec = folio_lruvec_lock(folio); 2504 2505 ClearPageHasHWPoisoned(head); 2506 2507 for (i = nr - 1; i >= 1; i--) { 2508 __split_huge_page_tail(head, i, lruvec, list); 2509 /* Some pages can be beyond EOF: drop them from page cache */ 2510 if (head[i].index >= end) { 2511 struct folio *tail = page_folio(head + i); 2512 2513 if (shmem_mapping(head->mapping)) 2514 shmem_uncharge(head->mapping->host, 1); 2515 else if (folio_test_clear_dirty(tail)) 2516 folio_account_cleaned(tail, 2517 inode_to_wb(folio->mapping->host)); 2518 __filemap_remove_folio(tail, NULL); 2519 folio_put(tail); 2520 } else if (!PageAnon(page)) { 2521 __xa_store(&head->mapping->i_pages, head[i].index, 2522 head + i, 0); 2523 } else if (swap_cache) { 2524 __xa_store(&swap_cache->i_pages, offset + i, 2525 head + i, 0); 2526 } 2527 } 2528 2529 ClearPageCompound(head); 2530 unlock_page_lruvec(lruvec); 2531 /* Caller disabled irqs, so they are still disabled here */ 2532 2533 split_page_owner(head, nr); 2534 2535 /* See comment in __split_huge_page_tail() */ 2536 if (PageAnon(head)) { 2537 /* Additional pin to swap cache */ 2538 if (PageSwapCache(head)) { 2539 page_ref_add(head, 2); 2540 xa_unlock(&swap_cache->i_pages); 2541 } else { 2542 page_ref_inc(head); 2543 } 2544 } else { 2545 /* Additional pin to page cache */ 2546 page_ref_add(head, 2); 2547 xa_unlock(&head->mapping->i_pages); 2548 } 2549 local_irq_enable(); 2550 2551 remap_page(folio, nr); 2552 2553 if (PageSwapCache(head)) { 2554 swp_entry_t entry = { .val = page_private(head) }; 2555 2556 split_swap_cluster(entry); 2557 } 2558 2559 for (i = 0; i < nr; i++) { 2560 struct page *subpage = head + i; 2561 if (subpage == page) 2562 continue; 2563 unlock_page(subpage); 2564 2565 /* 2566 * Subpages may be freed if there wasn't any mapping 2567 * like if add_to_swap() is running on a lru page that 2568 * had its mapping zapped. And freeing these pages 2569 * requires taking the lru_lock so we do the put_page 2570 * of the tail pages after the split is complete. 2571 */ 2572 free_page_and_swap_cache(subpage); 2573 } 2574 } 2575 2576 /* Racy check whether the huge page can be split */ 2577 bool can_split_folio(struct folio *folio, int *pextra_pins) 2578 { 2579 int extra_pins; 2580 2581 /* Additional pins from page cache */ 2582 if (folio_test_anon(folio)) 2583 extra_pins = folio_test_swapcache(folio) ? 2584 folio_nr_pages(folio) : 0; 2585 else 2586 extra_pins = folio_nr_pages(folio); 2587 if (pextra_pins) 2588 *pextra_pins = extra_pins; 2589 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2590 } 2591 2592 /* 2593 * This function splits huge page into normal pages. @page can point to any 2594 * subpage of huge page to split. Split doesn't change the position of @page. 2595 * 2596 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2597 * The huge page must be locked. 2598 * 2599 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2600 * 2601 * Both head page and tail pages will inherit mapping, flags, and so on from 2602 * the hugepage. 2603 * 2604 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2605 * they are not mapped. 2606 * 2607 * Returns 0 if the hugepage is split successfully. 2608 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2609 * us. 2610 */ 2611 int split_huge_page_to_list(struct page *page, struct list_head *list) 2612 { 2613 struct folio *folio = page_folio(page); 2614 struct page *head = &folio->page; 2615 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2616 XA_STATE(xas, &head->mapping->i_pages, head->index); 2617 struct anon_vma *anon_vma = NULL; 2618 struct address_space *mapping = NULL; 2619 int extra_pins, ret; 2620 pgoff_t end; 2621 bool is_hzp; 2622 2623 VM_BUG_ON_PAGE(!PageLocked(head), head); 2624 VM_BUG_ON_PAGE(!PageCompound(head), head); 2625 2626 is_hzp = is_huge_zero_page(head); 2627 VM_WARN_ON_ONCE_PAGE(is_hzp, head); 2628 if (is_hzp) 2629 return -EBUSY; 2630 2631 if (PageWriteback(head)) 2632 return -EBUSY; 2633 2634 if (PageAnon(head)) { 2635 /* 2636 * The caller does not necessarily hold an mmap_lock that would 2637 * prevent the anon_vma disappearing so we first we take a 2638 * reference to it and then lock the anon_vma for write. This 2639 * is similar to folio_lock_anon_vma_read except the write lock 2640 * is taken to serialise against parallel split or collapse 2641 * operations. 2642 */ 2643 anon_vma = page_get_anon_vma(head); 2644 if (!anon_vma) { 2645 ret = -EBUSY; 2646 goto out; 2647 } 2648 end = -1; 2649 mapping = NULL; 2650 anon_vma_lock_write(anon_vma); 2651 } else { 2652 mapping = head->mapping; 2653 2654 /* Truncated ? */ 2655 if (!mapping) { 2656 ret = -EBUSY; 2657 goto out; 2658 } 2659 2660 xas_split_alloc(&xas, head, compound_order(head), 2661 mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK); 2662 if (xas_error(&xas)) { 2663 ret = xas_error(&xas); 2664 goto out; 2665 } 2666 2667 anon_vma = NULL; 2668 i_mmap_lock_read(mapping); 2669 2670 /* 2671 *__split_huge_page() may need to trim off pages beyond EOF: 2672 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2673 * which cannot be nested inside the page tree lock. So note 2674 * end now: i_size itself may be changed at any moment, but 2675 * head page lock is good enough to serialize the trimming. 2676 */ 2677 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2678 if (shmem_mapping(mapping)) 2679 end = shmem_fallocend(mapping->host, end); 2680 } 2681 2682 /* 2683 * Racy check if we can split the page, before unmap_page() will 2684 * split PMDs 2685 */ 2686 if (!can_split_folio(folio, &extra_pins)) { 2687 ret = -EBUSY; 2688 goto out_unlock; 2689 } 2690 2691 unmap_page(head); 2692 2693 /* block interrupt reentry in xa_lock and spinlock */ 2694 local_irq_disable(); 2695 if (mapping) { 2696 /* 2697 * Check if the head page is present in page cache. 2698 * We assume all tail are present too, if head is there. 2699 */ 2700 xas_lock(&xas); 2701 xas_reset(&xas); 2702 if (xas_load(&xas) != head) 2703 goto fail; 2704 } 2705 2706 /* Prevent deferred_split_scan() touching ->_refcount */ 2707 spin_lock(&ds_queue->split_queue_lock); 2708 if (page_ref_freeze(head, 1 + extra_pins)) { 2709 if (!list_empty(page_deferred_list(head))) { 2710 ds_queue->split_queue_len--; 2711 list_del(page_deferred_list(head)); 2712 } 2713 spin_unlock(&ds_queue->split_queue_lock); 2714 if (mapping) { 2715 int nr = thp_nr_pages(head); 2716 2717 xas_split(&xas, head, thp_order(head)); 2718 if (PageSwapBacked(head)) { 2719 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2720 -nr); 2721 } else { 2722 __mod_lruvec_page_state(head, NR_FILE_THPS, 2723 -nr); 2724 filemap_nr_thps_dec(mapping); 2725 } 2726 } 2727 2728 __split_huge_page(page, list, end); 2729 ret = 0; 2730 } else { 2731 spin_unlock(&ds_queue->split_queue_lock); 2732 fail: 2733 if (mapping) 2734 xas_unlock(&xas); 2735 local_irq_enable(); 2736 remap_page(folio, folio_nr_pages(folio)); 2737 ret = -EBUSY; 2738 } 2739 2740 out_unlock: 2741 if (anon_vma) { 2742 anon_vma_unlock_write(anon_vma); 2743 put_anon_vma(anon_vma); 2744 } 2745 if (mapping) 2746 i_mmap_unlock_read(mapping); 2747 out: 2748 xas_destroy(&xas); 2749 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2750 return ret; 2751 } 2752 2753 void free_transhuge_page(struct page *page) 2754 { 2755 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2756 unsigned long flags; 2757 2758 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2759 if (!list_empty(page_deferred_list(page))) { 2760 ds_queue->split_queue_len--; 2761 list_del(page_deferred_list(page)); 2762 } 2763 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2764 free_compound_page(page); 2765 } 2766 2767 void deferred_split_huge_page(struct page *page) 2768 { 2769 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2770 #ifdef CONFIG_MEMCG 2771 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2772 #endif 2773 unsigned long flags; 2774 2775 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2776 2777 /* 2778 * The try_to_unmap() in page reclaim path might reach here too, 2779 * this may cause a race condition to corrupt deferred split queue. 2780 * And, if page reclaim is already handling the same page, it is 2781 * unnecessary to handle it again in shrinker. 2782 * 2783 * Check PageSwapCache to determine if the page is being 2784 * handled by page reclaim since THP swap would add the page into 2785 * swap cache before calling try_to_unmap(). 2786 */ 2787 if (PageSwapCache(page)) 2788 return; 2789 2790 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2791 if (list_empty(page_deferred_list(page))) { 2792 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2793 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2794 ds_queue->split_queue_len++; 2795 #ifdef CONFIG_MEMCG 2796 if (memcg) 2797 set_shrinker_bit(memcg, page_to_nid(page), 2798 deferred_split_shrinker.id); 2799 #endif 2800 } 2801 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2802 } 2803 2804 static unsigned long deferred_split_count(struct shrinker *shrink, 2805 struct shrink_control *sc) 2806 { 2807 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2808 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2809 2810 #ifdef CONFIG_MEMCG 2811 if (sc->memcg) 2812 ds_queue = &sc->memcg->deferred_split_queue; 2813 #endif 2814 return READ_ONCE(ds_queue->split_queue_len); 2815 } 2816 2817 static unsigned long deferred_split_scan(struct shrinker *shrink, 2818 struct shrink_control *sc) 2819 { 2820 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2821 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2822 unsigned long flags; 2823 LIST_HEAD(list), *pos, *next; 2824 struct page *page; 2825 int split = 0; 2826 2827 #ifdef CONFIG_MEMCG 2828 if (sc->memcg) 2829 ds_queue = &sc->memcg->deferred_split_queue; 2830 #endif 2831 2832 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2833 /* Take pin on all head pages to avoid freeing them under us */ 2834 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2835 page = list_entry((void *)pos, struct page, deferred_list); 2836 page = compound_head(page); 2837 if (get_page_unless_zero(page)) { 2838 list_move(page_deferred_list(page), &list); 2839 } else { 2840 /* We lost race with put_compound_page() */ 2841 list_del_init(page_deferred_list(page)); 2842 ds_queue->split_queue_len--; 2843 } 2844 if (!--sc->nr_to_scan) 2845 break; 2846 } 2847 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2848 2849 list_for_each_safe(pos, next, &list) { 2850 page = list_entry((void *)pos, struct page, deferred_list); 2851 if (!trylock_page(page)) 2852 goto next; 2853 /* split_huge_page() removes page from list on success */ 2854 if (!split_huge_page(page)) 2855 split++; 2856 unlock_page(page); 2857 next: 2858 put_page(page); 2859 } 2860 2861 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2862 list_splice_tail(&list, &ds_queue->split_queue); 2863 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2864 2865 /* 2866 * Stop shrinker if we didn't split any page, but the queue is empty. 2867 * This can happen if pages were freed under us. 2868 */ 2869 if (!split && list_empty(&ds_queue->split_queue)) 2870 return SHRINK_STOP; 2871 return split; 2872 } 2873 2874 static struct shrinker deferred_split_shrinker = { 2875 .count_objects = deferred_split_count, 2876 .scan_objects = deferred_split_scan, 2877 .seeks = DEFAULT_SEEKS, 2878 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2879 SHRINKER_NONSLAB, 2880 }; 2881 2882 #ifdef CONFIG_DEBUG_FS 2883 static void split_huge_pages_all(void) 2884 { 2885 struct zone *zone; 2886 struct page *page; 2887 unsigned long pfn, max_zone_pfn; 2888 unsigned long total = 0, split = 0; 2889 2890 pr_debug("Split all THPs\n"); 2891 for_each_zone(zone) { 2892 if (!managed_zone(zone)) 2893 continue; 2894 max_zone_pfn = zone_end_pfn(zone); 2895 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2896 int nr_pages; 2897 2898 page = pfn_to_online_page(pfn); 2899 if (!page || !get_page_unless_zero(page)) 2900 continue; 2901 2902 if (zone != page_zone(page)) 2903 goto next; 2904 2905 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2906 goto next; 2907 2908 total++; 2909 lock_page(page); 2910 nr_pages = thp_nr_pages(page); 2911 if (!split_huge_page(page)) 2912 split++; 2913 pfn += nr_pages - 1; 2914 unlock_page(page); 2915 next: 2916 put_page(page); 2917 cond_resched(); 2918 } 2919 } 2920 2921 pr_debug("%lu of %lu THP split\n", split, total); 2922 } 2923 2924 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2925 { 2926 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2927 is_vm_hugetlb_page(vma); 2928 } 2929 2930 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2931 unsigned long vaddr_end) 2932 { 2933 int ret = 0; 2934 struct task_struct *task; 2935 struct mm_struct *mm; 2936 unsigned long total = 0, split = 0; 2937 unsigned long addr; 2938 2939 vaddr_start &= PAGE_MASK; 2940 vaddr_end &= PAGE_MASK; 2941 2942 /* Find the task_struct from pid */ 2943 rcu_read_lock(); 2944 task = find_task_by_vpid(pid); 2945 if (!task) { 2946 rcu_read_unlock(); 2947 ret = -ESRCH; 2948 goto out; 2949 } 2950 get_task_struct(task); 2951 rcu_read_unlock(); 2952 2953 /* Find the mm_struct */ 2954 mm = get_task_mm(task); 2955 put_task_struct(task); 2956 2957 if (!mm) { 2958 ret = -EINVAL; 2959 goto out; 2960 } 2961 2962 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 2963 pid, vaddr_start, vaddr_end); 2964 2965 mmap_read_lock(mm); 2966 /* 2967 * always increase addr by PAGE_SIZE, since we could have a PTE page 2968 * table filled with PTE-mapped THPs, each of which is distinct. 2969 */ 2970 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 2971 struct vm_area_struct *vma = vma_lookup(mm, addr); 2972 struct page *page; 2973 2974 if (!vma) 2975 break; 2976 2977 /* skip special VMA and hugetlb VMA */ 2978 if (vma_not_suitable_for_thp_split(vma)) { 2979 addr = vma->vm_end; 2980 continue; 2981 } 2982 2983 /* FOLL_DUMP to ignore special (like zero) pages */ 2984 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 2985 2986 if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) 2987 continue; 2988 2989 if (!is_transparent_hugepage(page)) 2990 goto next; 2991 2992 total++; 2993 if (!can_split_folio(page_folio(page), NULL)) 2994 goto next; 2995 2996 if (!trylock_page(page)) 2997 goto next; 2998 2999 if (!split_huge_page(page)) 3000 split++; 3001 3002 unlock_page(page); 3003 next: 3004 put_page(page); 3005 cond_resched(); 3006 } 3007 mmap_read_unlock(mm); 3008 mmput(mm); 3009 3010 pr_debug("%lu of %lu THP split\n", split, total); 3011 3012 out: 3013 return ret; 3014 } 3015 3016 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3017 pgoff_t off_end) 3018 { 3019 struct filename *file; 3020 struct file *candidate; 3021 struct address_space *mapping; 3022 int ret = -EINVAL; 3023 pgoff_t index; 3024 int nr_pages = 1; 3025 unsigned long total = 0, split = 0; 3026 3027 file = getname_kernel(file_path); 3028 if (IS_ERR(file)) 3029 return ret; 3030 3031 candidate = file_open_name(file, O_RDONLY, 0); 3032 if (IS_ERR(candidate)) 3033 goto out; 3034 3035 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3036 file_path, off_start, off_end); 3037 3038 mapping = candidate->f_mapping; 3039 3040 for (index = off_start; index < off_end; index += nr_pages) { 3041 struct page *fpage = pagecache_get_page(mapping, index, 3042 FGP_ENTRY | FGP_HEAD, 0); 3043 3044 nr_pages = 1; 3045 if (xa_is_value(fpage) || !fpage) 3046 continue; 3047 3048 if (!is_transparent_hugepage(fpage)) 3049 goto next; 3050 3051 total++; 3052 nr_pages = thp_nr_pages(fpage); 3053 3054 if (!trylock_page(fpage)) 3055 goto next; 3056 3057 if (!split_huge_page(fpage)) 3058 split++; 3059 3060 unlock_page(fpage); 3061 next: 3062 put_page(fpage); 3063 cond_resched(); 3064 } 3065 3066 filp_close(candidate, NULL); 3067 ret = 0; 3068 3069 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3070 out: 3071 putname(file); 3072 return ret; 3073 } 3074 3075 #define MAX_INPUT_BUF_SZ 255 3076 3077 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3078 size_t count, loff_t *ppops) 3079 { 3080 static DEFINE_MUTEX(split_debug_mutex); 3081 ssize_t ret; 3082 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3083 char input_buf[MAX_INPUT_BUF_SZ]; 3084 int pid; 3085 unsigned long vaddr_start, vaddr_end; 3086 3087 ret = mutex_lock_interruptible(&split_debug_mutex); 3088 if (ret) 3089 return ret; 3090 3091 ret = -EFAULT; 3092 3093 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3094 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3095 goto out; 3096 3097 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3098 3099 if (input_buf[0] == '/') { 3100 char *tok; 3101 char *buf = input_buf; 3102 char file_path[MAX_INPUT_BUF_SZ]; 3103 pgoff_t off_start = 0, off_end = 0; 3104 size_t input_len = strlen(input_buf); 3105 3106 tok = strsep(&buf, ","); 3107 if (tok) { 3108 strcpy(file_path, tok); 3109 } else { 3110 ret = -EINVAL; 3111 goto out; 3112 } 3113 3114 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3115 if (ret != 2) { 3116 ret = -EINVAL; 3117 goto out; 3118 } 3119 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3120 if (!ret) 3121 ret = input_len; 3122 3123 goto out; 3124 } 3125 3126 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3127 if (ret == 1 && pid == 1) { 3128 split_huge_pages_all(); 3129 ret = strlen(input_buf); 3130 goto out; 3131 } else if (ret != 3) { 3132 ret = -EINVAL; 3133 goto out; 3134 } 3135 3136 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3137 if (!ret) 3138 ret = strlen(input_buf); 3139 out: 3140 mutex_unlock(&split_debug_mutex); 3141 return ret; 3142 3143 } 3144 3145 static const struct file_operations split_huge_pages_fops = { 3146 .owner = THIS_MODULE, 3147 .write = split_huge_pages_write, 3148 .llseek = no_llseek, 3149 }; 3150 3151 static int __init split_huge_pages_debugfs(void) 3152 { 3153 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3154 &split_huge_pages_fops); 3155 return 0; 3156 } 3157 late_initcall(split_huge_pages_debugfs); 3158 #endif 3159 3160 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3161 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3162 struct page *page) 3163 { 3164 struct vm_area_struct *vma = pvmw->vma; 3165 struct mm_struct *mm = vma->vm_mm; 3166 unsigned long address = pvmw->address; 3167 bool anon_exclusive; 3168 pmd_t pmdval; 3169 swp_entry_t entry; 3170 pmd_t pmdswp; 3171 3172 if (!(pvmw->pmd && !pvmw->pte)) 3173 return 0; 3174 3175 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3176 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3177 3178 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3179 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3180 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3181 return -EBUSY; 3182 } 3183 3184 if (pmd_dirty(pmdval)) 3185 set_page_dirty(page); 3186 if (pmd_write(pmdval)) 3187 entry = make_writable_migration_entry(page_to_pfn(page)); 3188 else if (anon_exclusive) 3189 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3190 else 3191 entry = make_readable_migration_entry(page_to_pfn(page)); 3192 pmdswp = swp_entry_to_pmd(entry); 3193 if (pmd_soft_dirty(pmdval)) 3194 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3195 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3196 page_remove_rmap(page, vma, true); 3197 put_page(page); 3198 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3199 3200 return 0; 3201 } 3202 3203 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3204 { 3205 struct vm_area_struct *vma = pvmw->vma; 3206 struct mm_struct *mm = vma->vm_mm; 3207 unsigned long address = pvmw->address; 3208 unsigned long haddr = address & HPAGE_PMD_MASK; 3209 pmd_t pmde; 3210 swp_entry_t entry; 3211 3212 if (!(pvmw->pmd && !pvmw->pte)) 3213 return; 3214 3215 entry = pmd_to_swp_entry(*pvmw->pmd); 3216 get_page(new); 3217 pmde = pmd_mkold(mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot))); 3218 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3219 pmde = pmd_mksoft_dirty(pmde); 3220 if (is_writable_migration_entry(entry)) 3221 pmde = maybe_pmd_mkwrite(pmde, vma); 3222 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3223 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3224 3225 if (PageAnon(new)) { 3226 rmap_t rmap_flags = RMAP_COMPOUND; 3227 3228 if (!is_readable_migration_entry(entry)) 3229 rmap_flags |= RMAP_EXCLUSIVE; 3230 3231 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3232 } else { 3233 page_add_file_rmap(new, vma, true); 3234 } 3235 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3236 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3237 3238 /* No need to invalidate - it was non-present before */ 3239 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3240 trace_remove_migration_pmd(address, pmd_val(pmde)); 3241 } 3242 #endif 3243