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/dax.h> 22 #include <linux/khugepaged.h> 23 #include <linux/freezer.h> 24 #include <linux/pfn_t.h> 25 #include <linux/mman.h> 26 #include <linux/memremap.h> 27 #include <linux/pagemap.h> 28 #include <linux/debugfs.h> 29 #include <linux/migrate.h> 30 #include <linux/hashtable.h> 31 #include <linux/userfaultfd_k.h> 32 #include <linux/page_idle.h> 33 #include <linux/shmem_fs.h> 34 #include <linux/oom.h> 35 #include <linux/numa.h> 36 #include <linux/page_owner.h> 37 #include <linux/sched/sysctl.h> 38 39 #include <asm/tlb.h> 40 #include <asm/pgalloc.h> 41 #include "internal.h" 42 43 #define CREATE_TRACE_POINTS 44 #include <trace/events/thp.h> 45 46 /* 47 * By default, transparent hugepage support is disabled in order to avoid 48 * risking an increased memory footprint for applications that are not 49 * guaranteed to benefit from it. When transparent hugepage support is 50 * enabled, it is for all mappings, and khugepaged scans all mappings. 51 * Defrag is invoked by khugepaged hugepage allocations and by page faults 52 * for all hugepage allocations. 53 */ 54 unsigned long transparent_hugepage_flags __read_mostly = 55 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 56 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 57 #endif 58 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 59 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 60 #endif 61 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 62 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 63 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 64 65 static struct shrinker deferred_split_shrinker; 66 67 static atomic_t huge_zero_refcount; 68 struct page *huge_zero_page __read_mostly; 69 unsigned long huge_zero_pfn __read_mostly = ~0UL; 70 71 static inline bool file_thp_enabled(struct vm_area_struct *vma) 72 { 73 return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file && 74 !inode_is_open_for_write(vma->vm_file->f_inode) && 75 (vma->vm_flags & VM_EXEC); 76 } 77 78 bool transparent_hugepage_active(struct vm_area_struct *vma) 79 { 80 /* The addr is used to check if the vma size fits */ 81 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; 82 83 if (!transhuge_vma_suitable(vma, addr)) 84 return false; 85 if (vma_is_anonymous(vma)) 86 return __transparent_hugepage_enabled(vma); 87 if (vma_is_shmem(vma)) 88 return shmem_huge_enabled(vma); 89 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) 90 return file_thp_enabled(vma); 91 92 return false; 93 } 94 95 static bool get_huge_zero_page(void) 96 { 97 struct page *zero_page; 98 retry: 99 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 100 return true; 101 102 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 103 HPAGE_PMD_ORDER); 104 if (!zero_page) { 105 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 106 return false; 107 } 108 count_vm_event(THP_ZERO_PAGE_ALLOC); 109 preempt_disable(); 110 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 111 preempt_enable(); 112 __free_pages(zero_page, compound_order(zero_page)); 113 goto retry; 114 } 115 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 116 117 /* We take additional reference here. It will be put back by shrinker */ 118 atomic_set(&huge_zero_refcount, 2); 119 preempt_enable(); 120 return true; 121 } 122 123 static void put_huge_zero_page(void) 124 { 125 /* 126 * Counter should never go to zero here. Only shrinker can put 127 * last reference. 128 */ 129 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 130 } 131 132 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 133 { 134 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 135 return READ_ONCE(huge_zero_page); 136 137 if (!get_huge_zero_page()) 138 return NULL; 139 140 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 141 put_huge_zero_page(); 142 143 return READ_ONCE(huge_zero_page); 144 } 145 146 void mm_put_huge_zero_page(struct mm_struct *mm) 147 { 148 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 149 put_huge_zero_page(); 150 } 151 152 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 153 struct shrink_control *sc) 154 { 155 /* we can free zero page only if last reference remains */ 156 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 157 } 158 159 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 160 struct shrink_control *sc) 161 { 162 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 163 struct page *zero_page = xchg(&huge_zero_page, NULL); 164 BUG_ON(zero_page == NULL); 165 WRITE_ONCE(huge_zero_pfn, ~0UL); 166 __free_pages(zero_page, compound_order(zero_page)); 167 return HPAGE_PMD_NR; 168 } 169 170 return 0; 171 } 172 173 static struct shrinker huge_zero_page_shrinker = { 174 .count_objects = shrink_huge_zero_page_count, 175 .scan_objects = shrink_huge_zero_page_scan, 176 .seeks = DEFAULT_SEEKS, 177 }; 178 179 #ifdef CONFIG_SYSFS 180 static ssize_t enabled_show(struct kobject *kobj, 181 struct kobj_attribute *attr, char *buf) 182 { 183 const char *output; 184 185 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 186 output = "[always] madvise never"; 187 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 188 &transparent_hugepage_flags)) 189 output = "always [madvise] never"; 190 else 191 output = "always madvise [never]"; 192 193 return sysfs_emit(buf, "%s\n", output); 194 } 195 196 static ssize_t enabled_store(struct kobject *kobj, 197 struct kobj_attribute *attr, 198 const char *buf, size_t count) 199 { 200 ssize_t ret = count; 201 202 if (sysfs_streq(buf, "always")) { 203 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 204 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 205 } else if (sysfs_streq(buf, "madvise")) { 206 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 207 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 208 } else if (sysfs_streq(buf, "never")) { 209 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 210 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 211 } else 212 ret = -EINVAL; 213 214 if (ret > 0) { 215 int err = start_stop_khugepaged(); 216 if (err) 217 ret = err; 218 } 219 return ret; 220 } 221 static struct kobj_attribute enabled_attr = 222 __ATTR(enabled, 0644, enabled_show, enabled_store); 223 224 ssize_t single_hugepage_flag_show(struct kobject *kobj, 225 struct kobj_attribute *attr, char *buf, 226 enum transparent_hugepage_flag flag) 227 { 228 return sysfs_emit(buf, "%d\n", 229 !!test_bit(flag, &transparent_hugepage_flags)); 230 } 231 232 ssize_t single_hugepage_flag_store(struct kobject *kobj, 233 struct kobj_attribute *attr, 234 const char *buf, size_t count, 235 enum transparent_hugepage_flag flag) 236 { 237 unsigned long value; 238 int ret; 239 240 ret = kstrtoul(buf, 10, &value); 241 if (ret < 0) 242 return ret; 243 if (value > 1) 244 return -EINVAL; 245 246 if (value) 247 set_bit(flag, &transparent_hugepage_flags); 248 else 249 clear_bit(flag, &transparent_hugepage_flags); 250 251 return count; 252 } 253 254 static ssize_t defrag_show(struct kobject *kobj, 255 struct kobj_attribute *attr, char *buf) 256 { 257 const char *output; 258 259 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 260 &transparent_hugepage_flags)) 261 output = "[always] defer defer+madvise madvise never"; 262 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 263 &transparent_hugepage_flags)) 264 output = "always [defer] defer+madvise madvise never"; 265 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 266 &transparent_hugepage_flags)) 267 output = "always defer [defer+madvise] madvise never"; 268 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 269 &transparent_hugepage_flags)) 270 output = "always defer defer+madvise [madvise] never"; 271 else 272 output = "always defer defer+madvise madvise [never]"; 273 274 return sysfs_emit(buf, "%s\n", output); 275 } 276 277 static ssize_t defrag_store(struct kobject *kobj, 278 struct kobj_attribute *attr, 279 const char *buf, size_t count) 280 { 281 if (sysfs_streq(buf, "always")) { 282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 283 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 284 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 285 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 286 } else if (sysfs_streq(buf, "defer+madvise")) { 287 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 288 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 289 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 290 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 291 } else if (sysfs_streq(buf, "defer")) { 292 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 293 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 294 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 295 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 296 } else if (sysfs_streq(buf, "madvise")) { 297 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 298 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 299 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 300 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 301 } else if (sysfs_streq(buf, "never")) { 302 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 303 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 304 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 305 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 306 } else 307 return -EINVAL; 308 309 return count; 310 } 311 static struct kobj_attribute defrag_attr = 312 __ATTR(defrag, 0644, defrag_show, defrag_store); 313 314 static ssize_t use_zero_page_show(struct kobject *kobj, 315 struct kobj_attribute *attr, char *buf) 316 { 317 return single_hugepage_flag_show(kobj, attr, buf, 318 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 319 } 320 static ssize_t use_zero_page_store(struct kobject *kobj, 321 struct kobj_attribute *attr, const char *buf, size_t count) 322 { 323 return single_hugepage_flag_store(kobj, attr, buf, count, 324 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 325 } 326 static struct kobj_attribute use_zero_page_attr = 327 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 328 329 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 330 struct kobj_attribute *attr, char *buf) 331 { 332 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 333 } 334 static struct kobj_attribute hpage_pmd_size_attr = 335 __ATTR_RO(hpage_pmd_size); 336 337 static struct attribute *hugepage_attr[] = { 338 &enabled_attr.attr, 339 &defrag_attr.attr, 340 &use_zero_page_attr.attr, 341 &hpage_pmd_size_attr.attr, 342 #ifdef CONFIG_SHMEM 343 &shmem_enabled_attr.attr, 344 #endif 345 NULL, 346 }; 347 348 static const struct attribute_group hugepage_attr_group = { 349 .attrs = hugepage_attr, 350 }; 351 352 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 353 { 354 int err; 355 356 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 357 if (unlikely(!*hugepage_kobj)) { 358 pr_err("failed to create transparent hugepage kobject\n"); 359 return -ENOMEM; 360 } 361 362 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 363 if (err) { 364 pr_err("failed to register transparent hugepage group\n"); 365 goto delete_obj; 366 } 367 368 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 369 if (err) { 370 pr_err("failed to register transparent hugepage group\n"); 371 goto remove_hp_group; 372 } 373 374 return 0; 375 376 remove_hp_group: 377 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 378 delete_obj: 379 kobject_put(*hugepage_kobj); 380 return err; 381 } 382 383 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 384 { 385 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 386 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 387 kobject_put(hugepage_kobj); 388 } 389 #else 390 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 391 { 392 return 0; 393 } 394 395 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 396 { 397 } 398 #endif /* CONFIG_SYSFS */ 399 400 static int __init hugepage_init(void) 401 { 402 int err; 403 struct kobject *hugepage_kobj; 404 405 if (!has_transparent_hugepage()) { 406 /* 407 * Hardware doesn't support hugepages, hence disable 408 * DAX PMD support. 409 */ 410 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 411 return -EINVAL; 412 } 413 414 /* 415 * hugepages can't be allocated by the buddy allocator 416 */ 417 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 418 /* 419 * we use page->mapping and page->index in second tail page 420 * as list_head: assuming THP order >= 2 421 */ 422 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 423 424 err = hugepage_init_sysfs(&hugepage_kobj); 425 if (err) 426 goto err_sysfs; 427 428 err = khugepaged_init(); 429 if (err) 430 goto err_slab; 431 432 err = register_shrinker(&huge_zero_page_shrinker); 433 if (err) 434 goto err_hzp_shrinker; 435 err = register_shrinker(&deferred_split_shrinker); 436 if (err) 437 goto err_split_shrinker; 438 439 /* 440 * By default disable transparent hugepages on smaller systems, 441 * where the extra memory used could hurt more than TLB overhead 442 * is likely to save. The admin can still enable it through /sys. 443 */ 444 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 445 transparent_hugepage_flags = 0; 446 return 0; 447 } 448 449 err = start_stop_khugepaged(); 450 if (err) 451 goto err_khugepaged; 452 453 return 0; 454 err_khugepaged: 455 unregister_shrinker(&deferred_split_shrinker); 456 err_split_shrinker: 457 unregister_shrinker(&huge_zero_page_shrinker); 458 err_hzp_shrinker: 459 khugepaged_destroy(); 460 err_slab: 461 hugepage_exit_sysfs(hugepage_kobj); 462 err_sysfs: 463 return err; 464 } 465 subsys_initcall(hugepage_init); 466 467 static int __init setup_transparent_hugepage(char *str) 468 { 469 int ret = 0; 470 if (!str) 471 goto out; 472 if (!strcmp(str, "always")) { 473 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 474 &transparent_hugepage_flags); 475 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 476 &transparent_hugepage_flags); 477 ret = 1; 478 } else if (!strcmp(str, "madvise")) { 479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 480 &transparent_hugepage_flags); 481 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 482 &transparent_hugepage_flags); 483 ret = 1; 484 } else if (!strcmp(str, "never")) { 485 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 486 &transparent_hugepage_flags); 487 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 488 &transparent_hugepage_flags); 489 ret = 1; 490 } 491 out: 492 if (!ret) 493 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 494 return ret; 495 } 496 __setup("transparent_hugepage=", setup_transparent_hugepage); 497 498 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 499 { 500 if (likely(vma->vm_flags & VM_WRITE)) 501 pmd = pmd_mkwrite(pmd); 502 return pmd; 503 } 504 505 #ifdef CONFIG_MEMCG 506 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 507 { 508 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 509 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 510 511 if (memcg) 512 return &memcg->deferred_split_queue; 513 else 514 return &pgdat->deferred_split_queue; 515 } 516 #else 517 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 518 { 519 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 520 521 return &pgdat->deferred_split_queue; 522 } 523 #endif 524 525 void prep_transhuge_page(struct page *page) 526 { 527 /* 528 * we use page->mapping and page->indexlru in second tail page 529 * as list_head: assuming THP order >= 2 530 */ 531 532 INIT_LIST_HEAD(page_deferred_list(page)); 533 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 534 } 535 536 static inline bool is_transparent_hugepage(struct page *page) 537 { 538 if (!PageCompound(page)) 539 return false; 540 541 page = compound_head(page); 542 return is_huge_zero_page(page) || 543 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 544 } 545 546 static unsigned long __thp_get_unmapped_area(struct file *filp, 547 unsigned long addr, unsigned long len, 548 loff_t off, unsigned long flags, unsigned long size) 549 { 550 loff_t off_end = off + len; 551 loff_t off_align = round_up(off, size); 552 unsigned long len_pad, ret; 553 554 if (off_end <= off_align || (off_end - off_align) < size) 555 return 0; 556 557 len_pad = len + size; 558 if (len_pad < len || (off + len_pad) < off) 559 return 0; 560 561 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 562 off >> PAGE_SHIFT, flags); 563 564 /* 565 * The failure might be due to length padding. The caller will retry 566 * without the padding. 567 */ 568 if (IS_ERR_VALUE(ret)) 569 return 0; 570 571 /* 572 * Do not try to align to THP boundary if allocation at the address 573 * hint succeeds. 574 */ 575 if (ret == addr) 576 return addr; 577 578 ret += (off - ret) & (size - 1); 579 return ret; 580 } 581 582 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 583 unsigned long len, unsigned long pgoff, unsigned long flags) 584 { 585 unsigned long ret; 586 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 587 588 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 589 if (ret) 590 return ret; 591 592 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 593 } 594 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 595 596 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 597 struct page *page, gfp_t gfp) 598 { 599 struct vm_area_struct *vma = vmf->vma; 600 pgtable_t pgtable; 601 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 602 vm_fault_t ret = 0; 603 604 VM_BUG_ON_PAGE(!PageCompound(page), page); 605 606 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) { 607 put_page(page); 608 count_vm_event(THP_FAULT_FALLBACK); 609 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 610 return VM_FAULT_FALLBACK; 611 } 612 cgroup_throttle_swaprate(page, gfp); 613 614 pgtable = pte_alloc_one(vma->vm_mm); 615 if (unlikely(!pgtable)) { 616 ret = VM_FAULT_OOM; 617 goto release; 618 } 619 620 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 621 /* 622 * The memory barrier inside __SetPageUptodate makes sure that 623 * clear_huge_page writes become visible before the set_pmd_at() 624 * write. 625 */ 626 __SetPageUptodate(page); 627 628 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 629 if (unlikely(!pmd_none(*vmf->pmd))) { 630 goto unlock_release; 631 } else { 632 pmd_t entry; 633 634 ret = check_stable_address_space(vma->vm_mm); 635 if (ret) 636 goto unlock_release; 637 638 /* Deliver the page fault to userland */ 639 if (userfaultfd_missing(vma)) { 640 spin_unlock(vmf->ptl); 641 put_page(page); 642 pte_free(vma->vm_mm, pgtable); 643 ret = handle_userfault(vmf, VM_UFFD_MISSING); 644 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 645 return ret; 646 } 647 648 entry = mk_huge_pmd(page, vma->vm_page_prot); 649 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 650 page_add_new_anon_rmap(page, vma, haddr, true); 651 lru_cache_add_inactive_or_unevictable(page, vma); 652 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 653 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 654 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 655 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 656 mm_inc_nr_ptes(vma->vm_mm); 657 spin_unlock(vmf->ptl); 658 count_vm_event(THP_FAULT_ALLOC); 659 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 660 } 661 662 return 0; 663 unlock_release: 664 spin_unlock(vmf->ptl); 665 release: 666 if (pgtable) 667 pte_free(vma->vm_mm, pgtable); 668 put_page(page); 669 return ret; 670 671 } 672 673 /* 674 * always: directly stall for all thp allocations 675 * defer: wake kswapd and fail if not immediately available 676 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 677 * fail if not immediately available 678 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 679 * available 680 * never: never stall for any thp allocation 681 */ 682 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 683 { 684 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 685 686 /* Always do synchronous compaction */ 687 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 688 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 689 690 /* Kick kcompactd and fail quickly */ 691 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 692 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 693 694 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 695 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 696 return GFP_TRANSHUGE_LIGHT | 697 (vma_madvised ? __GFP_DIRECT_RECLAIM : 698 __GFP_KSWAPD_RECLAIM); 699 700 /* Only do synchronous compaction if madvised */ 701 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 702 return GFP_TRANSHUGE_LIGHT | 703 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 704 705 return GFP_TRANSHUGE_LIGHT; 706 } 707 708 /* Caller must hold page table lock. */ 709 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 710 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 711 struct page *zero_page) 712 { 713 pmd_t entry; 714 if (!pmd_none(*pmd)) 715 return; 716 entry = mk_pmd(zero_page, vma->vm_page_prot); 717 entry = pmd_mkhuge(entry); 718 if (pgtable) 719 pgtable_trans_huge_deposit(mm, pmd, pgtable); 720 set_pmd_at(mm, haddr, pmd, entry); 721 mm_inc_nr_ptes(mm); 722 } 723 724 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 725 { 726 struct vm_area_struct *vma = vmf->vma; 727 gfp_t gfp; 728 struct page *page; 729 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 730 731 if (!transhuge_vma_suitable(vma, haddr)) 732 return VM_FAULT_FALLBACK; 733 if (unlikely(anon_vma_prepare(vma))) 734 return VM_FAULT_OOM; 735 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 736 return VM_FAULT_OOM; 737 if (!(vmf->flags & FAULT_FLAG_WRITE) && 738 !mm_forbids_zeropage(vma->vm_mm) && 739 transparent_hugepage_use_zero_page()) { 740 pgtable_t pgtable; 741 struct page *zero_page; 742 vm_fault_t ret; 743 pgtable = pte_alloc_one(vma->vm_mm); 744 if (unlikely(!pgtable)) 745 return VM_FAULT_OOM; 746 zero_page = mm_get_huge_zero_page(vma->vm_mm); 747 if (unlikely(!zero_page)) { 748 pte_free(vma->vm_mm, pgtable); 749 count_vm_event(THP_FAULT_FALLBACK); 750 return VM_FAULT_FALLBACK; 751 } 752 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 753 ret = 0; 754 if (pmd_none(*vmf->pmd)) { 755 ret = check_stable_address_space(vma->vm_mm); 756 if (ret) { 757 spin_unlock(vmf->ptl); 758 pte_free(vma->vm_mm, pgtable); 759 } else if (userfaultfd_missing(vma)) { 760 spin_unlock(vmf->ptl); 761 pte_free(vma->vm_mm, pgtable); 762 ret = handle_userfault(vmf, VM_UFFD_MISSING); 763 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 764 } else { 765 set_huge_zero_page(pgtable, vma->vm_mm, vma, 766 haddr, vmf->pmd, zero_page); 767 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 768 spin_unlock(vmf->ptl); 769 } 770 } else { 771 spin_unlock(vmf->ptl); 772 pte_free(vma->vm_mm, pgtable); 773 } 774 return ret; 775 } 776 gfp = vma_thp_gfp_mask(vma); 777 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); 778 if (unlikely(!page)) { 779 count_vm_event(THP_FAULT_FALLBACK); 780 return VM_FAULT_FALLBACK; 781 } 782 prep_transhuge_page(page); 783 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 784 } 785 786 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 787 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 788 pgtable_t pgtable) 789 { 790 struct mm_struct *mm = vma->vm_mm; 791 pmd_t entry; 792 spinlock_t *ptl; 793 794 ptl = pmd_lock(mm, pmd); 795 if (!pmd_none(*pmd)) { 796 if (write) { 797 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 798 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 799 goto out_unlock; 800 } 801 entry = pmd_mkyoung(*pmd); 802 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 803 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 804 update_mmu_cache_pmd(vma, addr, pmd); 805 } 806 807 goto out_unlock; 808 } 809 810 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 811 if (pfn_t_devmap(pfn)) 812 entry = pmd_mkdevmap(entry); 813 if (write) { 814 entry = pmd_mkyoung(pmd_mkdirty(entry)); 815 entry = maybe_pmd_mkwrite(entry, vma); 816 } 817 818 if (pgtable) { 819 pgtable_trans_huge_deposit(mm, pmd, pgtable); 820 mm_inc_nr_ptes(mm); 821 pgtable = NULL; 822 } 823 824 set_pmd_at(mm, addr, pmd, entry); 825 update_mmu_cache_pmd(vma, addr, pmd); 826 827 out_unlock: 828 spin_unlock(ptl); 829 if (pgtable) 830 pte_free(mm, pgtable); 831 } 832 833 /** 834 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn 835 * @vmf: Structure describing the fault 836 * @pfn: pfn to insert 837 * @pgprot: page protection to use 838 * @write: whether it's a write fault 839 * 840 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 841 * also consult the vmf_insert_mixed_prot() documentation when 842 * @pgprot != @vmf->vma->vm_page_prot. 843 * 844 * Return: vm_fault_t value. 845 */ 846 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 847 pgprot_t pgprot, bool write) 848 { 849 unsigned long addr = vmf->address & PMD_MASK; 850 struct vm_area_struct *vma = vmf->vma; 851 pgtable_t pgtable = NULL; 852 853 /* 854 * If we had pmd_special, we could avoid all these restrictions, 855 * but we need to be consistent with PTEs and architectures that 856 * can't support a 'special' bit. 857 */ 858 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 859 !pfn_t_devmap(pfn)); 860 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 861 (VM_PFNMAP|VM_MIXEDMAP)); 862 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 863 864 if (addr < vma->vm_start || addr >= vma->vm_end) 865 return VM_FAULT_SIGBUS; 866 867 if (arch_needs_pgtable_deposit()) { 868 pgtable = pte_alloc_one(vma->vm_mm); 869 if (!pgtable) 870 return VM_FAULT_OOM; 871 } 872 873 track_pfn_insert(vma, &pgprot, pfn); 874 875 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 876 return VM_FAULT_NOPAGE; 877 } 878 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 879 880 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 881 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 882 { 883 if (likely(vma->vm_flags & VM_WRITE)) 884 pud = pud_mkwrite(pud); 885 return pud; 886 } 887 888 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 889 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 890 { 891 struct mm_struct *mm = vma->vm_mm; 892 pud_t entry; 893 spinlock_t *ptl; 894 895 ptl = pud_lock(mm, pud); 896 if (!pud_none(*pud)) { 897 if (write) { 898 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 899 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 900 goto out_unlock; 901 } 902 entry = pud_mkyoung(*pud); 903 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 904 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 905 update_mmu_cache_pud(vma, addr, pud); 906 } 907 goto out_unlock; 908 } 909 910 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 911 if (pfn_t_devmap(pfn)) 912 entry = pud_mkdevmap(entry); 913 if (write) { 914 entry = pud_mkyoung(pud_mkdirty(entry)); 915 entry = maybe_pud_mkwrite(entry, vma); 916 } 917 set_pud_at(mm, addr, pud, entry); 918 update_mmu_cache_pud(vma, addr, pud); 919 920 out_unlock: 921 spin_unlock(ptl); 922 } 923 924 /** 925 * vmf_insert_pfn_pud_prot - insert a pud size pfn 926 * @vmf: Structure describing the fault 927 * @pfn: pfn to insert 928 * @pgprot: page protection to use 929 * @write: whether it's a write fault 930 * 931 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 932 * also consult the vmf_insert_mixed_prot() documentation when 933 * @pgprot != @vmf->vma->vm_page_prot. 934 * 935 * Return: vm_fault_t value. 936 */ 937 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 938 pgprot_t pgprot, bool write) 939 { 940 unsigned long addr = vmf->address & PUD_MASK; 941 struct vm_area_struct *vma = vmf->vma; 942 943 /* 944 * If we had pud_special, we could avoid all these restrictions, 945 * but we need to be consistent with PTEs and architectures that 946 * can't support a 'special' bit. 947 */ 948 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 949 !pfn_t_devmap(pfn)); 950 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 951 (VM_PFNMAP|VM_MIXEDMAP)); 952 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 953 954 if (addr < vma->vm_start || addr >= vma->vm_end) 955 return VM_FAULT_SIGBUS; 956 957 track_pfn_insert(vma, &pgprot, pfn); 958 959 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 960 return VM_FAULT_NOPAGE; 961 } 962 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 963 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 964 965 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 966 pmd_t *pmd, int flags) 967 { 968 pmd_t _pmd; 969 970 _pmd = pmd_mkyoung(*pmd); 971 if (flags & FOLL_WRITE) 972 _pmd = pmd_mkdirty(_pmd); 973 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 974 pmd, _pmd, flags & FOLL_WRITE)) 975 update_mmu_cache_pmd(vma, addr, pmd); 976 } 977 978 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 979 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 980 { 981 unsigned long pfn = pmd_pfn(*pmd); 982 struct mm_struct *mm = vma->vm_mm; 983 struct page *page; 984 985 assert_spin_locked(pmd_lockptr(mm, pmd)); 986 987 /* 988 * When we COW a devmap PMD entry, we split it into PTEs, so we should 989 * not be in this function with `flags & FOLL_COW` set. 990 */ 991 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 992 993 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 994 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 995 (FOLL_PIN | FOLL_GET))) 996 return NULL; 997 998 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 999 return NULL; 1000 1001 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1002 /* pass */; 1003 else 1004 return NULL; 1005 1006 if (flags & FOLL_TOUCH) 1007 touch_pmd(vma, addr, pmd, flags); 1008 1009 /* 1010 * device mapped pages can only be returned if the 1011 * caller will manage the page reference count. 1012 */ 1013 if (!(flags & (FOLL_GET | FOLL_PIN))) 1014 return ERR_PTR(-EEXIST); 1015 1016 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1017 *pgmap = get_dev_pagemap(pfn, *pgmap); 1018 if (!*pgmap) 1019 return ERR_PTR(-EFAULT); 1020 page = pfn_to_page(pfn); 1021 if (!try_grab_page(page, flags)) 1022 page = ERR_PTR(-ENOMEM); 1023 1024 return page; 1025 } 1026 1027 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1028 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1029 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1030 { 1031 spinlock_t *dst_ptl, *src_ptl; 1032 struct page *src_page; 1033 pmd_t pmd; 1034 pgtable_t pgtable = NULL; 1035 int ret = -ENOMEM; 1036 1037 /* Skip if can be re-fill on fault */ 1038 if (!vma_is_anonymous(dst_vma)) 1039 return 0; 1040 1041 pgtable = pte_alloc_one(dst_mm); 1042 if (unlikely(!pgtable)) 1043 goto out; 1044 1045 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1046 src_ptl = pmd_lockptr(src_mm, src_pmd); 1047 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1048 1049 ret = -EAGAIN; 1050 pmd = *src_pmd; 1051 1052 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1053 if (unlikely(is_swap_pmd(pmd))) { 1054 swp_entry_t entry = pmd_to_swp_entry(pmd); 1055 1056 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1057 if (is_writable_migration_entry(entry)) { 1058 entry = make_readable_migration_entry( 1059 swp_offset(entry)); 1060 pmd = swp_entry_to_pmd(entry); 1061 if (pmd_swp_soft_dirty(*src_pmd)) 1062 pmd = pmd_swp_mksoft_dirty(pmd); 1063 if (pmd_swp_uffd_wp(*src_pmd)) 1064 pmd = pmd_swp_mkuffd_wp(pmd); 1065 set_pmd_at(src_mm, addr, src_pmd, pmd); 1066 } 1067 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1068 mm_inc_nr_ptes(dst_mm); 1069 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1070 if (!userfaultfd_wp(dst_vma)) 1071 pmd = pmd_swp_clear_uffd_wp(pmd); 1072 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1073 ret = 0; 1074 goto out_unlock; 1075 } 1076 #endif 1077 1078 if (unlikely(!pmd_trans_huge(pmd))) { 1079 pte_free(dst_mm, pgtable); 1080 goto out_unlock; 1081 } 1082 /* 1083 * When page table lock is held, the huge zero pmd should not be 1084 * under splitting since we don't split the page itself, only pmd to 1085 * a page table. 1086 */ 1087 if (is_huge_zero_pmd(pmd)) { 1088 /* 1089 * get_huge_zero_page() will never allocate a new page here, 1090 * since we already have a zero page to copy. It just takes a 1091 * reference. 1092 */ 1093 mm_get_huge_zero_page(dst_mm); 1094 goto out_zero_page; 1095 } 1096 1097 src_page = pmd_page(pmd); 1098 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1099 1100 /* 1101 * If this page is a potentially pinned page, split and retry the fault 1102 * with smaller page size. Normally this should not happen because the 1103 * userspace should use MADV_DONTFORK upon pinned regions. This is a 1104 * best effort that the pinned pages won't be replaced by another 1105 * random page during the coming copy-on-write. 1106 */ 1107 if (unlikely(page_needs_cow_for_dma(src_vma, src_page))) { 1108 pte_free(dst_mm, pgtable); 1109 spin_unlock(src_ptl); 1110 spin_unlock(dst_ptl); 1111 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1112 return -EAGAIN; 1113 } 1114 1115 get_page(src_page); 1116 page_dup_rmap(src_page, true); 1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1118 out_zero_page: 1119 mm_inc_nr_ptes(dst_mm); 1120 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1121 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1122 if (!userfaultfd_wp(dst_vma)) 1123 pmd = pmd_clear_uffd_wp(pmd); 1124 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1125 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1126 1127 ret = 0; 1128 out_unlock: 1129 spin_unlock(src_ptl); 1130 spin_unlock(dst_ptl); 1131 out: 1132 return ret; 1133 } 1134 1135 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1136 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1137 pud_t *pud, int flags) 1138 { 1139 pud_t _pud; 1140 1141 _pud = pud_mkyoung(*pud); 1142 if (flags & FOLL_WRITE) 1143 _pud = pud_mkdirty(_pud); 1144 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1145 pud, _pud, flags & FOLL_WRITE)) 1146 update_mmu_cache_pud(vma, addr, pud); 1147 } 1148 1149 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1150 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1151 { 1152 unsigned long pfn = pud_pfn(*pud); 1153 struct mm_struct *mm = vma->vm_mm; 1154 struct page *page; 1155 1156 assert_spin_locked(pud_lockptr(mm, pud)); 1157 1158 if (flags & FOLL_WRITE && !pud_write(*pud)) 1159 return NULL; 1160 1161 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1162 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1163 (FOLL_PIN | FOLL_GET))) 1164 return NULL; 1165 1166 if (pud_present(*pud) && pud_devmap(*pud)) 1167 /* pass */; 1168 else 1169 return NULL; 1170 1171 if (flags & FOLL_TOUCH) 1172 touch_pud(vma, addr, pud, flags); 1173 1174 /* 1175 * device mapped pages can only be returned if the 1176 * caller will manage the page reference count. 1177 * 1178 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1179 */ 1180 if (!(flags & (FOLL_GET | FOLL_PIN))) 1181 return ERR_PTR(-EEXIST); 1182 1183 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1184 *pgmap = get_dev_pagemap(pfn, *pgmap); 1185 if (!*pgmap) 1186 return ERR_PTR(-EFAULT); 1187 page = pfn_to_page(pfn); 1188 if (!try_grab_page(page, flags)) 1189 page = ERR_PTR(-ENOMEM); 1190 1191 return page; 1192 } 1193 1194 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1195 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1196 struct vm_area_struct *vma) 1197 { 1198 spinlock_t *dst_ptl, *src_ptl; 1199 pud_t pud; 1200 int ret; 1201 1202 dst_ptl = pud_lock(dst_mm, dst_pud); 1203 src_ptl = pud_lockptr(src_mm, src_pud); 1204 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1205 1206 ret = -EAGAIN; 1207 pud = *src_pud; 1208 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1209 goto out_unlock; 1210 1211 /* 1212 * When page table lock is held, the huge zero pud should not be 1213 * under splitting since we don't split the page itself, only pud to 1214 * a page table. 1215 */ 1216 if (is_huge_zero_pud(pud)) { 1217 /* No huge zero pud yet */ 1218 } 1219 1220 /* Please refer to comments in copy_huge_pmd() */ 1221 if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) { 1222 spin_unlock(src_ptl); 1223 spin_unlock(dst_ptl); 1224 __split_huge_pud(vma, src_pud, addr); 1225 return -EAGAIN; 1226 } 1227 1228 pudp_set_wrprotect(src_mm, addr, src_pud); 1229 pud = pud_mkold(pud_wrprotect(pud)); 1230 set_pud_at(dst_mm, addr, dst_pud, pud); 1231 1232 ret = 0; 1233 out_unlock: 1234 spin_unlock(src_ptl); 1235 spin_unlock(dst_ptl); 1236 return ret; 1237 } 1238 1239 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1240 { 1241 pud_t entry; 1242 unsigned long haddr; 1243 bool write = vmf->flags & FAULT_FLAG_WRITE; 1244 1245 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1246 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1247 goto unlock; 1248 1249 entry = pud_mkyoung(orig_pud); 1250 if (write) 1251 entry = pud_mkdirty(entry); 1252 haddr = vmf->address & HPAGE_PUD_MASK; 1253 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1254 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1255 1256 unlock: 1257 spin_unlock(vmf->ptl); 1258 } 1259 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1260 1261 void huge_pmd_set_accessed(struct vm_fault *vmf) 1262 { 1263 pmd_t entry; 1264 unsigned long haddr; 1265 bool write = vmf->flags & FAULT_FLAG_WRITE; 1266 pmd_t orig_pmd = vmf->orig_pmd; 1267 1268 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1269 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1270 goto unlock; 1271 1272 entry = pmd_mkyoung(orig_pmd); 1273 if (write) 1274 entry = pmd_mkdirty(entry); 1275 haddr = vmf->address & HPAGE_PMD_MASK; 1276 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1277 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1278 1279 unlock: 1280 spin_unlock(vmf->ptl); 1281 } 1282 1283 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1284 { 1285 struct vm_area_struct *vma = vmf->vma; 1286 struct page *page; 1287 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1288 pmd_t orig_pmd = vmf->orig_pmd; 1289 1290 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1291 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1292 1293 if (is_huge_zero_pmd(orig_pmd)) 1294 goto fallback; 1295 1296 spin_lock(vmf->ptl); 1297 1298 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1299 spin_unlock(vmf->ptl); 1300 return 0; 1301 } 1302 1303 page = pmd_page(orig_pmd); 1304 VM_BUG_ON_PAGE(!PageHead(page), page); 1305 1306 if (!trylock_page(page)) { 1307 get_page(page); 1308 spin_unlock(vmf->ptl); 1309 lock_page(page); 1310 spin_lock(vmf->ptl); 1311 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1312 spin_unlock(vmf->ptl); 1313 unlock_page(page); 1314 put_page(page); 1315 return 0; 1316 } 1317 put_page(page); 1318 } 1319 1320 /* 1321 * See do_wp_page(): we can only map the page writable if there are 1322 * no additional references. Note that we always drain the LRU 1323 * pagevecs immediately after adding a THP. 1324 */ 1325 if (page_count(page) > 1 + PageSwapCache(page) * thp_nr_pages(page)) 1326 goto unlock_fallback; 1327 if (PageSwapCache(page)) 1328 try_to_free_swap(page); 1329 if (page_count(page) == 1) { 1330 pmd_t entry; 1331 entry = pmd_mkyoung(orig_pmd); 1332 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1333 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1334 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1335 unlock_page(page); 1336 spin_unlock(vmf->ptl); 1337 return VM_FAULT_WRITE; 1338 } 1339 1340 unlock_fallback: 1341 unlock_page(page); 1342 spin_unlock(vmf->ptl); 1343 fallback: 1344 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1345 return VM_FAULT_FALLBACK; 1346 } 1347 1348 /* 1349 * FOLL_FORCE can write to even unwritable pmd's, but only 1350 * after we've gone through a COW cycle and they are dirty. 1351 */ 1352 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1353 { 1354 return pmd_write(pmd) || 1355 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1356 } 1357 1358 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1359 unsigned long addr, 1360 pmd_t *pmd, 1361 unsigned int flags) 1362 { 1363 struct mm_struct *mm = vma->vm_mm; 1364 struct page *page = NULL; 1365 1366 assert_spin_locked(pmd_lockptr(mm, pmd)); 1367 1368 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1369 goto out; 1370 1371 /* Avoid dumping huge zero page */ 1372 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1373 return ERR_PTR(-EFAULT); 1374 1375 /* Full NUMA hinting faults to serialise migration in fault paths */ 1376 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1377 goto out; 1378 1379 page = pmd_page(*pmd); 1380 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1381 1382 if (!try_grab_page(page, flags)) 1383 return ERR_PTR(-ENOMEM); 1384 1385 if (flags & FOLL_TOUCH) 1386 touch_pmd(vma, addr, pmd, flags); 1387 1388 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1389 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1390 1391 out: 1392 return page; 1393 } 1394 1395 /* NUMA hinting page fault entry point for trans huge pmds */ 1396 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1397 { 1398 struct vm_area_struct *vma = vmf->vma; 1399 pmd_t oldpmd = vmf->orig_pmd; 1400 pmd_t pmd; 1401 struct page *page; 1402 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1403 int page_nid = NUMA_NO_NODE; 1404 int target_nid, last_cpupid = -1; 1405 bool migrated = false; 1406 bool was_writable = pmd_savedwrite(oldpmd); 1407 int flags = 0; 1408 1409 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1410 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1411 spin_unlock(vmf->ptl); 1412 goto out; 1413 } 1414 1415 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1416 page = vm_normal_page_pmd(vma, haddr, pmd); 1417 if (!page) 1418 goto out_map; 1419 1420 /* See similar comment in do_numa_page for explanation */ 1421 if (!was_writable) 1422 flags |= TNF_NO_GROUP; 1423 1424 page_nid = page_to_nid(page); 1425 last_cpupid = page_cpupid_last(page); 1426 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1427 &flags); 1428 1429 if (target_nid == NUMA_NO_NODE) { 1430 put_page(page); 1431 goto out_map; 1432 } 1433 1434 spin_unlock(vmf->ptl); 1435 1436 migrated = migrate_misplaced_page(page, vma, target_nid); 1437 if (migrated) { 1438 flags |= TNF_MIGRATED; 1439 page_nid = target_nid; 1440 } else { 1441 flags |= TNF_MIGRATE_FAIL; 1442 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1443 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1444 spin_unlock(vmf->ptl); 1445 goto out; 1446 } 1447 goto out_map; 1448 } 1449 1450 out: 1451 if (page_nid != NUMA_NO_NODE) 1452 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1453 flags); 1454 1455 return 0; 1456 1457 out_map: 1458 /* Restore the PMD */ 1459 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1460 pmd = pmd_mkyoung(pmd); 1461 if (was_writable) 1462 pmd = pmd_mkwrite(pmd); 1463 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1464 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1465 spin_unlock(vmf->ptl); 1466 goto out; 1467 } 1468 1469 /* 1470 * Return true if we do MADV_FREE successfully on entire pmd page. 1471 * Otherwise, return false. 1472 */ 1473 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1474 pmd_t *pmd, unsigned long addr, unsigned long next) 1475 { 1476 spinlock_t *ptl; 1477 pmd_t orig_pmd; 1478 struct page *page; 1479 struct mm_struct *mm = tlb->mm; 1480 bool ret = false; 1481 1482 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1483 1484 ptl = pmd_trans_huge_lock(pmd, vma); 1485 if (!ptl) 1486 goto out_unlocked; 1487 1488 orig_pmd = *pmd; 1489 if (is_huge_zero_pmd(orig_pmd)) 1490 goto out; 1491 1492 if (unlikely(!pmd_present(orig_pmd))) { 1493 VM_BUG_ON(thp_migration_supported() && 1494 !is_pmd_migration_entry(orig_pmd)); 1495 goto out; 1496 } 1497 1498 page = pmd_page(orig_pmd); 1499 /* 1500 * If other processes are mapping this page, we couldn't discard 1501 * the page unless they all do MADV_FREE so let's skip the page. 1502 */ 1503 if (total_mapcount(page) != 1) 1504 goto out; 1505 1506 if (!trylock_page(page)) 1507 goto out; 1508 1509 /* 1510 * If user want to discard part-pages of THP, split it so MADV_FREE 1511 * will deactivate only them. 1512 */ 1513 if (next - addr != HPAGE_PMD_SIZE) { 1514 get_page(page); 1515 spin_unlock(ptl); 1516 split_huge_page(page); 1517 unlock_page(page); 1518 put_page(page); 1519 goto out_unlocked; 1520 } 1521 1522 if (PageDirty(page)) 1523 ClearPageDirty(page); 1524 unlock_page(page); 1525 1526 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1527 pmdp_invalidate(vma, addr, pmd); 1528 orig_pmd = pmd_mkold(orig_pmd); 1529 orig_pmd = pmd_mkclean(orig_pmd); 1530 1531 set_pmd_at(mm, addr, pmd, orig_pmd); 1532 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1533 } 1534 1535 mark_page_lazyfree(page); 1536 ret = true; 1537 out: 1538 spin_unlock(ptl); 1539 out_unlocked: 1540 return ret; 1541 } 1542 1543 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1544 { 1545 pgtable_t pgtable; 1546 1547 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1548 pte_free(mm, pgtable); 1549 mm_dec_nr_ptes(mm); 1550 } 1551 1552 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1553 pmd_t *pmd, unsigned long addr) 1554 { 1555 pmd_t orig_pmd; 1556 spinlock_t *ptl; 1557 1558 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1559 1560 ptl = __pmd_trans_huge_lock(pmd, vma); 1561 if (!ptl) 1562 return 0; 1563 /* 1564 * For architectures like ppc64 we look at deposited pgtable 1565 * when calling pmdp_huge_get_and_clear. So do the 1566 * pgtable_trans_huge_withdraw after finishing pmdp related 1567 * operations. 1568 */ 1569 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1570 tlb->fullmm); 1571 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1572 if (vma_is_special_huge(vma)) { 1573 if (arch_needs_pgtable_deposit()) 1574 zap_deposited_table(tlb->mm, pmd); 1575 spin_unlock(ptl); 1576 } else if (is_huge_zero_pmd(orig_pmd)) { 1577 zap_deposited_table(tlb->mm, pmd); 1578 spin_unlock(ptl); 1579 } else { 1580 struct page *page = NULL; 1581 int flush_needed = 1; 1582 1583 if (pmd_present(orig_pmd)) { 1584 page = pmd_page(orig_pmd); 1585 page_remove_rmap(page, vma, true); 1586 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1587 VM_BUG_ON_PAGE(!PageHead(page), page); 1588 } else if (thp_migration_supported()) { 1589 swp_entry_t entry; 1590 1591 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1592 entry = pmd_to_swp_entry(orig_pmd); 1593 page = pfn_swap_entry_to_page(entry); 1594 flush_needed = 0; 1595 } else 1596 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1597 1598 if (PageAnon(page)) { 1599 zap_deposited_table(tlb->mm, pmd); 1600 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1601 } else { 1602 if (arch_needs_pgtable_deposit()) 1603 zap_deposited_table(tlb->mm, pmd); 1604 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1605 } 1606 1607 spin_unlock(ptl); 1608 if (flush_needed) 1609 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1610 } 1611 return 1; 1612 } 1613 1614 #ifndef pmd_move_must_withdraw 1615 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1616 spinlock_t *old_pmd_ptl, 1617 struct vm_area_struct *vma) 1618 { 1619 /* 1620 * With split pmd lock we also need to move preallocated 1621 * PTE page table if new_pmd is on different PMD page table. 1622 * 1623 * We also don't deposit and withdraw tables for file pages. 1624 */ 1625 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1626 } 1627 #endif 1628 1629 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1630 { 1631 #ifdef CONFIG_MEM_SOFT_DIRTY 1632 if (unlikely(is_pmd_migration_entry(pmd))) 1633 pmd = pmd_swp_mksoft_dirty(pmd); 1634 else if (pmd_present(pmd)) 1635 pmd = pmd_mksoft_dirty(pmd); 1636 #endif 1637 return pmd; 1638 } 1639 1640 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1641 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1642 { 1643 spinlock_t *old_ptl, *new_ptl; 1644 pmd_t pmd; 1645 struct mm_struct *mm = vma->vm_mm; 1646 bool force_flush = false; 1647 1648 /* 1649 * The destination pmd shouldn't be established, free_pgtables() 1650 * should have release it. 1651 */ 1652 if (WARN_ON(!pmd_none(*new_pmd))) { 1653 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1654 return false; 1655 } 1656 1657 /* 1658 * We don't have to worry about the ordering of src and dst 1659 * ptlocks because exclusive mmap_lock prevents deadlock. 1660 */ 1661 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1662 if (old_ptl) { 1663 new_ptl = pmd_lockptr(mm, new_pmd); 1664 if (new_ptl != old_ptl) 1665 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1666 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1667 if (pmd_present(pmd)) 1668 force_flush = true; 1669 VM_BUG_ON(!pmd_none(*new_pmd)); 1670 1671 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1672 pgtable_t pgtable; 1673 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1674 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1675 } 1676 pmd = move_soft_dirty_pmd(pmd); 1677 set_pmd_at(mm, new_addr, new_pmd, pmd); 1678 if (force_flush) 1679 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1680 if (new_ptl != old_ptl) 1681 spin_unlock(new_ptl); 1682 spin_unlock(old_ptl); 1683 return true; 1684 } 1685 return false; 1686 } 1687 1688 /* 1689 * Returns 1690 * - 0 if PMD could not be locked 1691 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1692 * or if prot_numa but THP migration is not supported 1693 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1694 */ 1695 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1696 unsigned long addr, pgprot_t newprot, unsigned long cp_flags) 1697 { 1698 struct mm_struct *mm = vma->vm_mm; 1699 spinlock_t *ptl; 1700 pmd_t entry; 1701 bool preserve_write; 1702 int ret; 1703 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1704 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1705 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1706 1707 if (prot_numa && !thp_migration_supported()) 1708 return 1; 1709 1710 ptl = __pmd_trans_huge_lock(pmd, vma); 1711 if (!ptl) 1712 return 0; 1713 1714 preserve_write = prot_numa && pmd_write(*pmd); 1715 ret = 1; 1716 1717 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1718 if (is_swap_pmd(*pmd)) { 1719 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1720 1721 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1722 if (is_writable_migration_entry(entry)) { 1723 pmd_t newpmd; 1724 /* 1725 * A protection check is difficult so 1726 * just be safe and disable write 1727 */ 1728 entry = make_readable_migration_entry( 1729 swp_offset(entry)); 1730 newpmd = swp_entry_to_pmd(entry); 1731 if (pmd_swp_soft_dirty(*pmd)) 1732 newpmd = pmd_swp_mksoft_dirty(newpmd); 1733 if (pmd_swp_uffd_wp(*pmd)) 1734 newpmd = pmd_swp_mkuffd_wp(newpmd); 1735 set_pmd_at(mm, addr, pmd, newpmd); 1736 } 1737 goto unlock; 1738 } 1739 #endif 1740 1741 if (prot_numa) { 1742 struct page *page; 1743 /* 1744 * Avoid trapping faults against the zero page. The read-only 1745 * data is likely to be read-cached on the local CPU and 1746 * local/remote hits to the zero page are not interesting. 1747 */ 1748 if (is_huge_zero_pmd(*pmd)) 1749 goto unlock; 1750 1751 if (pmd_protnone(*pmd)) 1752 goto unlock; 1753 1754 page = pmd_page(*pmd); 1755 /* 1756 * Skip scanning top tier node if normal numa 1757 * balancing is disabled 1758 */ 1759 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1760 node_is_toptier(page_to_nid(page))) 1761 goto unlock; 1762 } 1763 /* 1764 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1765 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1766 * which is also under mmap_read_lock(mm): 1767 * 1768 * CPU0: CPU1: 1769 * change_huge_pmd(prot_numa=1) 1770 * pmdp_huge_get_and_clear_notify() 1771 * madvise_dontneed() 1772 * zap_pmd_range() 1773 * pmd_trans_huge(*pmd) == 0 (without ptl) 1774 * // skip the pmd 1775 * set_pmd_at(); 1776 * // pmd is re-established 1777 * 1778 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1779 * which may break userspace. 1780 * 1781 * pmdp_invalidate() is required to make sure we don't miss 1782 * dirty/young flags set by hardware. 1783 */ 1784 entry = pmdp_invalidate(vma, addr, pmd); 1785 1786 entry = pmd_modify(entry, newprot); 1787 if (preserve_write) 1788 entry = pmd_mk_savedwrite(entry); 1789 if (uffd_wp) { 1790 entry = pmd_wrprotect(entry); 1791 entry = pmd_mkuffd_wp(entry); 1792 } else if (uffd_wp_resolve) { 1793 /* 1794 * Leave the write bit to be handled by PF interrupt 1795 * handler, then things like COW could be properly 1796 * handled. 1797 */ 1798 entry = pmd_clear_uffd_wp(entry); 1799 } 1800 ret = HPAGE_PMD_NR; 1801 set_pmd_at(mm, addr, pmd, entry); 1802 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1803 unlock: 1804 spin_unlock(ptl); 1805 return ret; 1806 } 1807 1808 /* 1809 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1810 * 1811 * Note that if it returns page table lock pointer, this routine returns without 1812 * unlocking page table lock. So callers must unlock it. 1813 */ 1814 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1815 { 1816 spinlock_t *ptl; 1817 ptl = pmd_lock(vma->vm_mm, pmd); 1818 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1819 pmd_devmap(*pmd))) 1820 return ptl; 1821 spin_unlock(ptl); 1822 return NULL; 1823 } 1824 1825 /* 1826 * Returns true if a given pud maps a thp, false otherwise. 1827 * 1828 * Note that if it returns true, this routine returns without unlocking page 1829 * table lock. So callers must unlock it. 1830 */ 1831 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1832 { 1833 spinlock_t *ptl; 1834 1835 ptl = pud_lock(vma->vm_mm, pud); 1836 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1837 return ptl; 1838 spin_unlock(ptl); 1839 return NULL; 1840 } 1841 1842 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1843 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1844 pud_t *pud, unsigned long addr) 1845 { 1846 spinlock_t *ptl; 1847 1848 ptl = __pud_trans_huge_lock(pud, vma); 1849 if (!ptl) 1850 return 0; 1851 /* 1852 * For architectures like ppc64 we look at deposited pgtable 1853 * when calling pudp_huge_get_and_clear. So do the 1854 * pgtable_trans_huge_withdraw after finishing pudp related 1855 * operations. 1856 */ 1857 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1858 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1859 if (vma_is_special_huge(vma)) { 1860 spin_unlock(ptl); 1861 /* No zero page support yet */ 1862 } else { 1863 /* No support for anonymous PUD pages yet */ 1864 BUG(); 1865 } 1866 return 1; 1867 } 1868 1869 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1870 unsigned long haddr) 1871 { 1872 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1873 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1874 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1875 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1876 1877 count_vm_event(THP_SPLIT_PUD); 1878 1879 pudp_huge_clear_flush_notify(vma, haddr, pud); 1880 } 1881 1882 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1883 unsigned long address) 1884 { 1885 spinlock_t *ptl; 1886 struct mmu_notifier_range range; 1887 1888 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1889 address & HPAGE_PUD_MASK, 1890 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1891 mmu_notifier_invalidate_range_start(&range); 1892 ptl = pud_lock(vma->vm_mm, pud); 1893 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1894 goto out; 1895 __split_huge_pud_locked(vma, pud, range.start); 1896 1897 out: 1898 spin_unlock(ptl); 1899 /* 1900 * No need to double call mmu_notifier->invalidate_range() callback as 1901 * the above pudp_huge_clear_flush_notify() did already call it. 1902 */ 1903 mmu_notifier_invalidate_range_only_end(&range); 1904 } 1905 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1906 1907 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 1908 unsigned long haddr, pmd_t *pmd) 1909 { 1910 struct mm_struct *mm = vma->vm_mm; 1911 pgtable_t pgtable; 1912 pmd_t _pmd; 1913 int i; 1914 1915 /* 1916 * Leave pmd empty until pte is filled note that it is fine to delay 1917 * notification until mmu_notifier_invalidate_range_end() as we are 1918 * replacing a zero pmd write protected page with a zero pte write 1919 * protected page. 1920 * 1921 * See Documentation/vm/mmu_notifier.rst 1922 */ 1923 pmdp_huge_clear_flush(vma, haddr, pmd); 1924 1925 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1926 pmd_populate(mm, &_pmd, pgtable); 1927 1928 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1929 pte_t *pte, entry; 1930 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 1931 entry = pte_mkspecial(entry); 1932 pte = pte_offset_map(&_pmd, haddr); 1933 VM_BUG_ON(!pte_none(*pte)); 1934 set_pte_at(mm, haddr, pte, entry); 1935 pte_unmap(pte); 1936 } 1937 smp_wmb(); /* make pte visible before pmd */ 1938 pmd_populate(mm, pmd, pgtable); 1939 } 1940 1941 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 1942 unsigned long haddr, bool freeze) 1943 { 1944 struct mm_struct *mm = vma->vm_mm; 1945 struct page *page; 1946 pgtable_t pgtable; 1947 pmd_t old_pmd, _pmd; 1948 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 1949 unsigned long addr; 1950 int i; 1951 1952 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 1953 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1954 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 1955 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 1956 && !pmd_devmap(*pmd)); 1957 1958 count_vm_event(THP_SPLIT_PMD); 1959 1960 if (!vma_is_anonymous(vma)) { 1961 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 1962 /* 1963 * We are going to unmap this huge page. So 1964 * just go ahead and zap it 1965 */ 1966 if (arch_needs_pgtable_deposit()) 1967 zap_deposited_table(mm, pmd); 1968 if (vma_is_special_huge(vma)) 1969 return; 1970 if (unlikely(is_pmd_migration_entry(old_pmd))) { 1971 swp_entry_t entry; 1972 1973 entry = pmd_to_swp_entry(old_pmd); 1974 page = pfn_swap_entry_to_page(entry); 1975 } else { 1976 page = pmd_page(old_pmd); 1977 if (!PageDirty(page) && pmd_dirty(old_pmd)) 1978 set_page_dirty(page); 1979 if (!PageReferenced(page) && pmd_young(old_pmd)) 1980 SetPageReferenced(page); 1981 page_remove_rmap(page, vma, true); 1982 put_page(page); 1983 } 1984 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 1985 return; 1986 } 1987 1988 if (is_huge_zero_pmd(*pmd)) { 1989 /* 1990 * FIXME: Do we want to invalidate secondary mmu by calling 1991 * mmu_notifier_invalidate_range() see comments below inside 1992 * __split_huge_pmd() ? 1993 * 1994 * We are going from a zero huge page write protected to zero 1995 * small page also write protected so it does not seems useful 1996 * to invalidate secondary mmu at this time. 1997 */ 1998 return __split_huge_zero_page_pmd(vma, haddr, pmd); 1999 } 2000 2001 /* 2002 * Up to this point the pmd is present and huge and userland has the 2003 * whole access to the hugepage during the split (which happens in 2004 * place). If we overwrite the pmd with the not-huge version pointing 2005 * to the pte here (which of course we could if all CPUs were bug 2006 * free), userland could trigger a small page size TLB miss on the 2007 * small sized TLB while the hugepage TLB entry is still established in 2008 * the huge TLB. Some CPU doesn't like that. 2009 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2010 * 383 on page 105. Intel should be safe but is also warns that it's 2011 * only safe if the permission and cache attributes of the two entries 2012 * loaded in the two TLB is identical (which should be the case here). 2013 * But it is generally safer to never allow small and huge TLB entries 2014 * for the same virtual address to be loaded simultaneously. So instead 2015 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2016 * current pmd notpresent (atomically because here the pmd_trans_huge 2017 * must remain set at all times on the pmd until the split is complete 2018 * for this pmd), then we flush the SMP TLB and finally we write the 2019 * non-huge version of the pmd entry with pmd_populate. 2020 */ 2021 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2022 2023 pmd_migration = is_pmd_migration_entry(old_pmd); 2024 if (unlikely(pmd_migration)) { 2025 swp_entry_t entry; 2026 2027 entry = pmd_to_swp_entry(old_pmd); 2028 page = pfn_swap_entry_to_page(entry); 2029 write = is_writable_migration_entry(entry); 2030 young = false; 2031 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2032 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2033 } else { 2034 page = pmd_page(old_pmd); 2035 if (pmd_dirty(old_pmd)) 2036 SetPageDirty(page); 2037 write = pmd_write(old_pmd); 2038 young = pmd_young(old_pmd); 2039 soft_dirty = pmd_soft_dirty(old_pmd); 2040 uffd_wp = pmd_uffd_wp(old_pmd); 2041 VM_BUG_ON_PAGE(!page_count(page), page); 2042 page_ref_add(page, HPAGE_PMD_NR - 1); 2043 } 2044 2045 /* 2046 * Withdraw the table only after we mark the pmd entry invalid. 2047 * This's critical for some architectures (Power). 2048 */ 2049 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2050 pmd_populate(mm, &_pmd, pgtable); 2051 2052 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2053 pte_t entry, *pte; 2054 /* 2055 * Note that NUMA hinting access restrictions are not 2056 * transferred to avoid any possibility of altering 2057 * permissions across VMAs. 2058 */ 2059 if (freeze || pmd_migration) { 2060 swp_entry_t swp_entry; 2061 if (write) 2062 swp_entry = make_writable_migration_entry( 2063 page_to_pfn(page + i)); 2064 else 2065 swp_entry = make_readable_migration_entry( 2066 page_to_pfn(page + i)); 2067 entry = swp_entry_to_pte(swp_entry); 2068 if (soft_dirty) 2069 entry = pte_swp_mksoft_dirty(entry); 2070 if (uffd_wp) 2071 entry = pte_swp_mkuffd_wp(entry); 2072 } else { 2073 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2074 entry = maybe_mkwrite(entry, vma); 2075 if (!write) 2076 entry = pte_wrprotect(entry); 2077 if (!young) 2078 entry = pte_mkold(entry); 2079 if (soft_dirty) 2080 entry = pte_mksoft_dirty(entry); 2081 if (uffd_wp) 2082 entry = pte_mkuffd_wp(entry); 2083 } 2084 pte = pte_offset_map(&_pmd, addr); 2085 BUG_ON(!pte_none(*pte)); 2086 set_pte_at(mm, addr, pte, entry); 2087 if (!pmd_migration) 2088 atomic_inc(&page[i]._mapcount); 2089 pte_unmap(pte); 2090 } 2091 2092 if (!pmd_migration) { 2093 /* 2094 * Set PG_double_map before dropping compound_mapcount to avoid 2095 * false-negative page_mapped(). 2096 */ 2097 if (compound_mapcount(page) > 1 && 2098 !TestSetPageDoubleMap(page)) { 2099 for (i = 0; i < HPAGE_PMD_NR; i++) 2100 atomic_inc(&page[i]._mapcount); 2101 } 2102 2103 lock_page_memcg(page); 2104 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2105 /* Last compound_mapcount is gone. */ 2106 __mod_lruvec_page_state(page, NR_ANON_THPS, 2107 -HPAGE_PMD_NR); 2108 if (TestClearPageDoubleMap(page)) { 2109 /* No need in mapcount reference anymore */ 2110 for (i = 0; i < HPAGE_PMD_NR; i++) 2111 atomic_dec(&page[i]._mapcount); 2112 } 2113 } 2114 unlock_page_memcg(page); 2115 2116 /* Above is effectively page_remove_rmap(page, vma, true) */ 2117 munlock_vma_page(page, vma, true); 2118 } 2119 2120 smp_wmb(); /* make pte visible before pmd */ 2121 pmd_populate(mm, pmd, pgtable); 2122 2123 if (freeze) { 2124 for (i = 0; i < HPAGE_PMD_NR; i++) { 2125 page_remove_rmap(page + i, vma, false); 2126 put_page(page + i); 2127 } 2128 } 2129 } 2130 2131 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2132 unsigned long address, bool freeze, struct folio *folio) 2133 { 2134 spinlock_t *ptl; 2135 struct mmu_notifier_range range; 2136 2137 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2138 address & HPAGE_PMD_MASK, 2139 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2140 mmu_notifier_invalidate_range_start(&range); 2141 ptl = pmd_lock(vma->vm_mm, pmd); 2142 2143 /* 2144 * If caller asks to setup a migration entry, we need a folio to check 2145 * pmd against. Otherwise we can end up replacing wrong folio. 2146 */ 2147 VM_BUG_ON(freeze && !folio); 2148 if (folio) { 2149 VM_WARN_ON_ONCE(!folio_test_locked(folio)); 2150 if (folio != page_folio(pmd_page(*pmd))) 2151 goto out; 2152 } 2153 2154 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2155 is_pmd_migration_entry(*pmd)) 2156 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2157 2158 out: 2159 spin_unlock(ptl); 2160 /* 2161 * No need to double call mmu_notifier->invalidate_range() callback. 2162 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2163 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2164 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2165 * fault will trigger a flush_notify before pointing to a new page 2166 * (it is fine if the secondary mmu keeps pointing to the old zero 2167 * page in the meantime) 2168 * 3) Split a huge pmd into pte pointing to the same page. No need 2169 * to invalidate secondary tlb entry they are all still valid. 2170 * any further changes to individual pte will notify. So no need 2171 * to call mmu_notifier->invalidate_range() 2172 */ 2173 mmu_notifier_invalidate_range_only_end(&range); 2174 } 2175 2176 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2177 bool freeze, struct folio *folio) 2178 { 2179 pgd_t *pgd; 2180 p4d_t *p4d; 2181 pud_t *pud; 2182 pmd_t *pmd; 2183 2184 pgd = pgd_offset(vma->vm_mm, address); 2185 if (!pgd_present(*pgd)) 2186 return; 2187 2188 p4d = p4d_offset(pgd, address); 2189 if (!p4d_present(*p4d)) 2190 return; 2191 2192 pud = pud_offset(p4d, address); 2193 if (!pud_present(*pud)) 2194 return; 2195 2196 pmd = pmd_offset(pud, address); 2197 2198 __split_huge_pmd(vma, pmd, address, freeze, folio); 2199 } 2200 2201 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2202 { 2203 /* 2204 * If the new address isn't hpage aligned and it could previously 2205 * contain an hugepage: check if we need to split an huge pmd. 2206 */ 2207 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2208 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2209 ALIGN(address, HPAGE_PMD_SIZE))) 2210 split_huge_pmd_address(vma, address, false, NULL); 2211 } 2212 2213 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2214 unsigned long start, 2215 unsigned long end, 2216 long adjust_next) 2217 { 2218 /* Check if we need to split start first. */ 2219 split_huge_pmd_if_needed(vma, start); 2220 2221 /* Check if we need to split end next. */ 2222 split_huge_pmd_if_needed(vma, end); 2223 2224 /* 2225 * If we're also updating the vma->vm_next->vm_start, 2226 * check if we need to split it. 2227 */ 2228 if (adjust_next > 0) { 2229 struct vm_area_struct *next = vma->vm_next; 2230 unsigned long nstart = next->vm_start; 2231 nstart += adjust_next; 2232 split_huge_pmd_if_needed(next, nstart); 2233 } 2234 } 2235 2236 static void unmap_page(struct page *page) 2237 { 2238 struct folio *folio = page_folio(page); 2239 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2240 TTU_SYNC; 2241 2242 VM_BUG_ON_PAGE(!PageHead(page), page); 2243 2244 /* 2245 * Anon pages need migration entries to preserve them, but file 2246 * pages can simply be left unmapped, then faulted back on demand. 2247 * If that is ever changed (perhaps for mlock), update remap_page(). 2248 */ 2249 if (folio_test_anon(folio)) 2250 try_to_migrate(folio, ttu_flags); 2251 else 2252 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2253 2254 VM_WARN_ON_ONCE_PAGE(page_mapped(page), page); 2255 } 2256 2257 static void remap_page(struct folio *folio, unsigned long nr) 2258 { 2259 int i = 0; 2260 2261 /* If unmap_page() uses try_to_migrate() on file, remove this check */ 2262 if (!folio_test_anon(folio)) 2263 return; 2264 for (;;) { 2265 remove_migration_ptes(folio, folio, true); 2266 i += folio_nr_pages(folio); 2267 if (i >= nr) 2268 break; 2269 folio = folio_next(folio); 2270 } 2271 } 2272 2273 static void lru_add_page_tail(struct page *head, struct page *tail, 2274 struct lruvec *lruvec, struct list_head *list) 2275 { 2276 VM_BUG_ON_PAGE(!PageHead(head), head); 2277 VM_BUG_ON_PAGE(PageCompound(tail), head); 2278 VM_BUG_ON_PAGE(PageLRU(tail), head); 2279 lockdep_assert_held(&lruvec->lru_lock); 2280 2281 if (list) { 2282 /* page reclaim is reclaiming a huge page */ 2283 VM_WARN_ON(PageLRU(head)); 2284 get_page(tail); 2285 list_add_tail(&tail->lru, list); 2286 } else { 2287 /* head is still on lru (and we have it frozen) */ 2288 VM_WARN_ON(!PageLRU(head)); 2289 if (PageUnevictable(tail)) 2290 tail->mlock_count = 0; 2291 else 2292 list_add_tail(&tail->lru, &head->lru); 2293 SetPageLRU(tail); 2294 } 2295 } 2296 2297 static void __split_huge_page_tail(struct page *head, int tail, 2298 struct lruvec *lruvec, struct list_head *list) 2299 { 2300 struct page *page_tail = head + tail; 2301 2302 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2303 2304 /* 2305 * Clone page flags before unfreezing refcount. 2306 * 2307 * After successful get_page_unless_zero() might follow flags change, 2308 * for example lock_page() which set PG_waiters. 2309 */ 2310 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2311 page_tail->flags |= (head->flags & 2312 ((1L << PG_referenced) | 2313 (1L << PG_swapbacked) | 2314 (1L << PG_swapcache) | 2315 (1L << PG_mlocked) | 2316 (1L << PG_uptodate) | 2317 (1L << PG_active) | 2318 (1L << PG_workingset) | 2319 (1L << PG_locked) | 2320 (1L << PG_unevictable) | 2321 #ifdef CONFIG_64BIT 2322 (1L << PG_arch_2) | 2323 #endif 2324 (1L << PG_dirty))); 2325 2326 /* ->mapping in first tail page is compound_mapcount */ 2327 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2328 page_tail); 2329 page_tail->mapping = head->mapping; 2330 page_tail->index = head->index + tail; 2331 2332 /* Page flags must be visible before we make the page non-compound. */ 2333 smp_wmb(); 2334 2335 /* 2336 * Clear PageTail before unfreezing page refcount. 2337 * 2338 * After successful get_page_unless_zero() might follow put_page() 2339 * which needs correct compound_head(). 2340 */ 2341 clear_compound_head(page_tail); 2342 2343 /* Finally unfreeze refcount. Additional reference from page cache. */ 2344 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2345 PageSwapCache(head))); 2346 2347 if (page_is_young(head)) 2348 set_page_young(page_tail); 2349 if (page_is_idle(head)) 2350 set_page_idle(page_tail); 2351 2352 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2353 2354 /* 2355 * always add to the tail because some iterators expect new 2356 * pages to show after the currently processed elements - e.g. 2357 * migrate_pages 2358 */ 2359 lru_add_page_tail(head, page_tail, lruvec, list); 2360 } 2361 2362 static void __split_huge_page(struct page *page, struct list_head *list, 2363 pgoff_t end) 2364 { 2365 struct folio *folio = page_folio(page); 2366 struct page *head = &folio->page; 2367 struct lruvec *lruvec; 2368 struct address_space *swap_cache = NULL; 2369 unsigned long offset = 0; 2370 unsigned int nr = thp_nr_pages(head); 2371 int i; 2372 2373 /* complete memcg works before add pages to LRU */ 2374 split_page_memcg(head, nr); 2375 2376 if (PageAnon(head) && PageSwapCache(head)) { 2377 swp_entry_t entry = { .val = page_private(head) }; 2378 2379 offset = swp_offset(entry); 2380 swap_cache = swap_address_space(entry); 2381 xa_lock(&swap_cache->i_pages); 2382 } 2383 2384 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2385 lruvec = folio_lruvec_lock(folio); 2386 2387 ClearPageHasHWPoisoned(head); 2388 2389 for (i = nr - 1; i >= 1; i--) { 2390 __split_huge_page_tail(head, i, lruvec, list); 2391 /* Some pages can be beyond EOF: drop them from page cache */ 2392 if (head[i].index >= end) { 2393 ClearPageDirty(head + i); 2394 __delete_from_page_cache(head + i, NULL); 2395 if (shmem_mapping(head->mapping)) 2396 shmem_uncharge(head->mapping->host, 1); 2397 put_page(head + i); 2398 } else if (!PageAnon(page)) { 2399 __xa_store(&head->mapping->i_pages, head[i].index, 2400 head + i, 0); 2401 } else if (swap_cache) { 2402 __xa_store(&swap_cache->i_pages, offset + i, 2403 head + i, 0); 2404 } 2405 } 2406 2407 ClearPageCompound(head); 2408 unlock_page_lruvec(lruvec); 2409 /* Caller disabled irqs, so they are still disabled here */ 2410 2411 split_page_owner(head, nr); 2412 2413 /* See comment in __split_huge_page_tail() */ 2414 if (PageAnon(head)) { 2415 /* Additional pin to swap cache */ 2416 if (PageSwapCache(head)) { 2417 page_ref_add(head, 2); 2418 xa_unlock(&swap_cache->i_pages); 2419 } else { 2420 page_ref_inc(head); 2421 } 2422 } else { 2423 /* Additional pin to page cache */ 2424 page_ref_add(head, 2); 2425 xa_unlock(&head->mapping->i_pages); 2426 } 2427 local_irq_enable(); 2428 2429 remap_page(folio, nr); 2430 2431 if (PageSwapCache(head)) { 2432 swp_entry_t entry = { .val = page_private(head) }; 2433 2434 split_swap_cluster(entry); 2435 } 2436 2437 for (i = 0; i < nr; i++) { 2438 struct page *subpage = head + i; 2439 if (subpage == page) 2440 continue; 2441 unlock_page(subpage); 2442 2443 /* 2444 * Subpages may be freed if there wasn't any mapping 2445 * like if add_to_swap() is running on a lru page that 2446 * had its mapping zapped. And freeing these pages 2447 * requires taking the lru_lock so we do the put_page 2448 * of the tail pages after the split is complete. 2449 */ 2450 put_page(subpage); 2451 } 2452 } 2453 2454 /* Racy check whether the huge page can be split */ 2455 bool can_split_folio(struct folio *folio, int *pextra_pins) 2456 { 2457 int extra_pins; 2458 2459 /* Additional pins from page cache */ 2460 if (folio_test_anon(folio)) 2461 extra_pins = folio_test_swapcache(folio) ? 2462 folio_nr_pages(folio) : 0; 2463 else 2464 extra_pins = folio_nr_pages(folio); 2465 if (pextra_pins) 2466 *pextra_pins = extra_pins; 2467 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2468 } 2469 2470 /* 2471 * This function splits huge page into normal pages. @page can point to any 2472 * subpage of huge page to split. Split doesn't change the position of @page. 2473 * 2474 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2475 * The huge page must be locked. 2476 * 2477 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2478 * 2479 * Both head page and tail pages will inherit mapping, flags, and so on from 2480 * the hugepage. 2481 * 2482 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2483 * they are not mapped. 2484 * 2485 * Returns 0 if the hugepage is split successfully. 2486 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2487 * us. 2488 */ 2489 int split_huge_page_to_list(struct page *page, struct list_head *list) 2490 { 2491 struct folio *folio = page_folio(page); 2492 struct page *head = &folio->page; 2493 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2494 XA_STATE(xas, &head->mapping->i_pages, head->index); 2495 struct anon_vma *anon_vma = NULL; 2496 struct address_space *mapping = NULL; 2497 int extra_pins, ret; 2498 pgoff_t end; 2499 2500 VM_BUG_ON_PAGE(is_huge_zero_page(head), head); 2501 VM_BUG_ON_PAGE(!PageLocked(head), head); 2502 VM_BUG_ON_PAGE(!PageCompound(head), head); 2503 2504 if (PageWriteback(head)) 2505 return -EBUSY; 2506 2507 if (PageAnon(head)) { 2508 /* 2509 * The caller does not necessarily hold an mmap_lock that would 2510 * prevent the anon_vma disappearing so we first we take a 2511 * reference to it and then lock the anon_vma for write. This 2512 * is similar to folio_lock_anon_vma_read except the write lock 2513 * is taken to serialise against parallel split or collapse 2514 * operations. 2515 */ 2516 anon_vma = page_get_anon_vma(head); 2517 if (!anon_vma) { 2518 ret = -EBUSY; 2519 goto out; 2520 } 2521 end = -1; 2522 mapping = NULL; 2523 anon_vma_lock_write(anon_vma); 2524 } else { 2525 mapping = head->mapping; 2526 2527 /* Truncated ? */ 2528 if (!mapping) { 2529 ret = -EBUSY; 2530 goto out; 2531 } 2532 2533 xas_split_alloc(&xas, head, compound_order(head), 2534 mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK); 2535 if (xas_error(&xas)) { 2536 ret = xas_error(&xas); 2537 goto out; 2538 } 2539 2540 anon_vma = NULL; 2541 i_mmap_lock_read(mapping); 2542 2543 /* 2544 *__split_huge_page() may need to trim off pages beyond EOF: 2545 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2546 * which cannot be nested inside the page tree lock. So note 2547 * end now: i_size itself may be changed at any moment, but 2548 * head page lock is good enough to serialize the trimming. 2549 */ 2550 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2551 if (shmem_mapping(mapping)) 2552 end = shmem_fallocend(mapping->host, end); 2553 } 2554 2555 /* 2556 * Racy check if we can split the page, before unmap_page() will 2557 * split PMDs 2558 */ 2559 if (!can_split_folio(folio, &extra_pins)) { 2560 ret = -EBUSY; 2561 goto out_unlock; 2562 } 2563 2564 unmap_page(head); 2565 2566 /* block interrupt reentry in xa_lock and spinlock */ 2567 local_irq_disable(); 2568 if (mapping) { 2569 /* 2570 * Check if the head page is present in page cache. 2571 * We assume all tail are present too, if head is there. 2572 */ 2573 xas_lock(&xas); 2574 xas_reset(&xas); 2575 if (xas_load(&xas) != head) 2576 goto fail; 2577 } 2578 2579 /* Prevent deferred_split_scan() touching ->_refcount */ 2580 spin_lock(&ds_queue->split_queue_lock); 2581 if (page_ref_freeze(head, 1 + extra_pins)) { 2582 if (!list_empty(page_deferred_list(head))) { 2583 ds_queue->split_queue_len--; 2584 list_del(page_deferred_list(head)); 2585 } 2586 spin_unlock(&ds_queue->split_queue_lock); 2587 if (mapping) { 2588 int nr = thp_nr_pages(head); 2589 2590 xas_split(&xas, head, thp_order(head)); 2591 if (PageSwapBacked(head)) { 2592 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2593 -nr); 2594 } else { 2595 __mod_lruvec_page_state(head, NR_FILE_THPS, 2596 -nr); 2597 filemap_nr_thps_dec(mapping); 2598 } 2599 } 2600 2601 __split_huge_page(page, list, end); 2602 ret = 0; 2603 } else { 2604 spin_unlock(&ds_queue->split_queue_lock); 2605 fail: 2606 if (mapping) 2607 xas_unlock(&xas); 2608 local_irq_enable(); 2609 remap_page(folio, folio_nr_pages(folio)); 2610 ret = -EBUSY; 2611 } 2612 2613 out_unlock: 2614 if (anon_vma) { 2615 anon_vma_unlock_write(anon_vma); 2616 put_anon_vma(anon_vma); 2617 } 2618 if (mapping) 2619 i_mmap_unlock_read(mapping); 2620 out: 2621 /* Free any memory we didn't use */ 2622 xas_nomem(&xas, 0); 2623 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2624 return ret; 2625 } 2626 2627 void free_transhuge_page(struct page *page) 2628 { 2629 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2630 unsigned long flags; 2631 2632 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2633 if (!list_empty(page_deferred_list(page))) { 2634 ds_queue->split_queue_len--; 2635 list_del(page_deferred_list(page)); 2636 } 2637 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2638 free_compound_page(page); 2639 } 2640 2641 void deferred_split_huge_page(struct page *page) 2642 { 2643 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2644 #ifdef CONFIG_MEMCG 2645 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2646 #endif 2647 unsigned long flags; 2648 2649 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2650 2651 /* 2652 * The try_to_unmap() in page reclaim path might reach here too, 2653 * this may cause a race condition to corrupt deferred split queue. 2654 * And, if page reclaim is already handling the same page, it is 2655 * unnecessary to handle it again in shrinker. 2656 * 2657 * Check PageSwapCache to determine if the page is being 2658 * handled by page reclaim since THP swap would add the page into 2659 * swap cache before calling try_to_unmap(). 2660 */ 2661 if (PageSwapCache(page)) 2662 return; 2663 2664 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2665 if (list_empty(page_deferred_list(page))) { 2666 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2667 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2668 ds_queue->split_queue_len++; 2669 #ifdef CONFIG_MEMCG 2670 if (memcg) 2671 set_shrinker_bit(memcg, page_to_nid(page), 2672 deferred_split_shrinker.id); 2673 #endif 2674 } 2675 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2676 } 2677 2678 static unsigned long deferred_split_count(struct shrinker *shrink, 2679 struct shrink_control *sc) 2680 { 2681 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2682 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2683 2684 #ifdef CONFIG_MEMCG 2685 if (sc->memcg) 2686 ds_queue = &sc->memcg->deferred_split_queue; 2687 #endif 2688 return READ_ONCE(ds_queue->split_queue_len); 2689 } 2690 2691 static unsigned long deferred_split_scan(struct shrinker *shrink, 2692 struct shrink_control *sc) 2693 { 2694 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2695 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2696 unsigned long flags; 2697 LIST_HEAD(list), *pos, *next; 2698 struct page *page; 2699 int split = 0; 2700 2701 #ifdef CONFIG_MEMCG 2702 if (sc->memcg) 2703 ds_queue = &sc->memcg->deferred_split_queue; 2704 #endif 2705 2706 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2707 /* Take pin on all head pages to avoid freeing them under us */ 2708 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2709 page = list_entry((void *)pos, struct page, deferred_list); 2710 page = compound_head(page); 2711 if (get_page_unless_zero(page)) { 2712 list_move(page_deferred_list(page), &list); 2713 } else { 2714 /* We lost race with put_compound_page() */ 2715 list_del_init(page_deferred_list(page)); 2716 ds_queue->split_queue_len--; 2717 } 2718 if (!--sc->nr_to_scan) 2719 break; 2720 } 2721 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2722 2723 list_for_each_safe(pos, next, &list) { 2724 page = list_entry((void *)pos, struct page, deferred_list); 2725 if (!trylock_page(page)) 2726 goto next; 2727 /* split_huge_page() removes page from list on success */ 2728 if (!split_huge_page(page)) 2729 split++; 2730 unlock_page(page); 2731 next: 2732 put_page(page); 2733 } 2734 2735 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2736 list_splice_tail(&list, &ds_queue->split_queue); 2737 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2738 2739 /* 2740 * Stop shrinker if we didn't split any page, but the queue is empty. 2741 * This can happen if pages were freed under us. 2742 */ 2743 if (!split && list_empty(&ds_queue->split_queue)) 2744 return SHRINK_STOP; 2745 return split; 2746 } 2747 2748 static struct shrinker deferred_split_shrinker = { 2749 .count_objects = deferred_split_count, 2750 .scan_objects = deferred_split_scan, 2751 .seeks = DEFAULT_SEEKS, 2752 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2753 SHRINKER_NONSLAB, 2754 }; 2755 2756 #ifdef CONFIG_DEBUG_FS 2757 static void split_huge_pages_all(void) 2758 { 2759 struct zone *zone; 2760 struct page *page; 2761 unsigned long pfn, max_zone_pfn; 2762 unsigned long total = 0, split = 0; 2763 2764 pr_debug("Split all THPs\n"); 2765 for_each_populated_zone(zone) { 2766 max_zone_pfn = zone_end_pfn(zone); 2767 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2768 if (!pfn_valid(pfn)) 2769 continue; 2770 2771 page = pfn_to_page(pfn); 2772 if (!get_page_unless_zero(page)) 2773 continue; 2774 2775 if (zone != page_zone(page)) 2776 goto next; 2777 2778 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2779 goto next; 2780 2781 total++; 2782 lock_page(page); 2783 if (!split_huge_page(page)) 2784 split++; 2785 unlock_page(page); 2786 next: 2787 put_page(page); 2788 cond_resched(); 2789 } 2790 } 2791 2792 pr_debug("%lu of %lu THP split\n", split, total); 2793 } 2794 2795 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2796 { 2797 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2798 is_vm_hugetlb_page(vma); 2799 } 2800 2801 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2802 unsigned long vaddr_end) 2803 { 2804 int ret = 0; 2805 struct task_struct *task; 2806 struct mm_struct *mm; 2807 unsigned long total = 0, split = 0; 2808 unsigned long addr; 2809 2810 vaddr_start &= PAGE_MASK; 2811 vaddr_end &= PAGE_MASK; 2812 2813 /* Find the task_struct from pid */ 2814 rcu_read_lock(); 2815 task = find_task_by_vpid(pid); 2816 if (!task) { 2817 rcu_read_unlock(); 2818 ret = -ESRCH; 2819 goto out; 2820 } 2821 get_task_struct(task); 2822 rcu_read_unlock(); 2823 2824 /* Find the mm_struct */ 2825 mm = get_task_mm(task); 2826 put_task_struct(task); 2827 2828 if (!mm) { 2829 ret = -EINVAL; 2830 goto out; 2831 } 2832 2833 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 2834 pid, vaddr_start, vaddr_end); 2835 2836 mmap_read_lock(mm); 2837 /* 2838 * always increase addr by PAGE_SIZE, since we could have a PTE page 2839 * table filled with PTE-mapped THPs, each of which is distinct. 2840 */ 2841 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 2842 struct vm_area_struct *vma = find_vma(mm, addr); 2843 struct page *page; 2844 2845 if (!vma || addr < vma->vm_start) 2846 break; 2847 2848 /* skip special VMA and hugetlb VMA */ 2849 if (vma_not_suitable_for_thp_split(vma)) { 2850 addr = vma->vm_end; 2851 continue; 2852 } 2853 2854 /* FOLL_DUMP to ignore special (like zero) pages */ 2855 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 2856 2857 if (IS_ERR(page)) 2858 continue; 2859 if (!page) 2860 continue; 2861 2862 if (!is_transparent_hugepage(page)) 2863 goto next; 2864 2865 total++; 2866 if (!can_split_folio(page_folio(page), NULL)) 2867 goto next; 2868 2869 if (!trylock_page(page)) 2870 goto next; 2871 2872 if (!split_huge_page(page)) 2873 split++; 2874 2875 unlock_page(page); 2876 next: 2877 put_page(page); 2878 cond_resched(); 2879 } 2880 mmap_read_unlock(mm); 2881 mmput(mm); 2882 2883 pr_debug("%lu of %lu THP split\n", split, total); 2884 2885 out: 2886 return ret; 2887 } 2888 2889 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 2890 pgoff_t off_end) 2891 { 2892 struct filename *file; 2893 struct file *candidate; 2894 struct address_space *mapping; 2895 int ret = -EINVAL; 2896 pgoff_t index; 2897 int nr_pages = 1; 2898 unsigned long total = 0, split = 0; 2899 2900 file = getname_kernel(file_path); 2901 if (IS_ERR(file)) 2902 return ret; 2903 2904 candidate = file_open_name(file, O_RDONLY, 0); 2905 if (IS_ERR(candidate)) 2906 goto out; 2907 2908 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 2909 file_path, off_start, off_end); 2910 2911 mapping = candidate->f_mapping; 2912 2913 for (index = off_start; index < off_end; index += nr_pages) { 2914 struct page *fpage = pagecache_get_page(mapping, index, 2915 FGP_ENTRY | FGP_HEAD, 0); 2916 2917 nr_pages = 1; 2918 if (xa_is_value(fpage) || !fpage) 2919 continue; 2920 2921 if (!is_transparent_hugepage(fpage)) 2922 goto next; 2923 2924 total++; 2925 nr_pages = thp_nr_pages(fpage); 2926 2927 if (!trylock_page(fpage)) 2928 goto next; 2929 2930 if (!split_huge_page(fpage)) 2931 split++; 2932 2933 unlock_page(fpage); 2934 next: 2935 put_page(fpage); 2936 cond_resched(); 2937 } 2938 2939 filp_close(candidate, NULL); 2940 ret = 0; 2941 2942 pr_debug("%lu of %lu file-backed THP split\n", split, total); 2943 out: 2944 putname(file); 2945 return ret; 2946 } 2947 2948 #define MAX_INPUT_BUF_SZ 255 2949 2950 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 2951 size_t count, loff_t *ppops) 2952 { 2953 static DEFINE_MUTEX(split_debug_mutex); 2954 ssize_t ret; 2955 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 2956 char input_buf[MAX_INPUT_BUF_SZ]; 2957 int pid; 2958 unsigned long vaddr_start, vaddr_end; 2959 2960 ret = mutex_lock_interruptible(&split_debug_mutex); 2961 if (ret) 2962 return ret; 2963 2964 ret = -EFAULT; 2965 2966 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 2967 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 2968 goto out; 2969 2970 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 2971 2972 if (input_buf[0] == '/') { 2973 char *tok; 2974 char *buf = input_buf; 2975 char file_path[MAX_INPUT_BUF_SZ]; 2976 pgoff_t off_start = 0, off_end = 0; 2977 size_t input_len = strlen(input_buf); 2978 2979 tok = strsep(&buf, ","); 2980 if (tok) { 2981 strcpy(file_path, tok); 2982 } else { 2983 ret = -EINVAL; 2984 goto out; 2985 } 2986 2987 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 2988 if (ret != 2) { 2989 ret = -EINVAL; 2990 goto out; 2991 } 2992 ret = split_huge_pages_in_file(file_path, off_start, off_end); 2993 if (!ret) 2994 ret = input_len; 2995 2996 goto out; 2997 } 2998 2999 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3000 if (ret == 1 && pid == 1) { 3001 split_huge_pages_all(); 3002 ret = strlen(input_buf); 3003 goto out; 3004 } else if (ret != 3) { 3005 ret = -EINVAL; 3006 goto out; 3007 } 3008 3009 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3010 if (!ret) 3011 ret = strlen(input_buf); 3012 out: 3013 mutex_unlock(&split_debug_mutex); 3014 return ret; 3015 3016 } 3017 3018 static const struct file_operations split_huge_pages_fops = { 3019 .owner = THIS_MODULE, 3020 .write = split_huge_pages_write, 3021 .llseek = no_llseek, 3022 }; 3023 3024 static int __init split_huge_pages_debugfs(void) 3025 { 3026 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3027 &split_huge_pages_fops); 3028 return 0; 3029 } 3030 late_initcall(split_huge_pages_debugfs); 3031 #endif 3032 3033 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3034 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3035 struct page *page) 3036 { 3037 struct vm_area_struct *vma = pvmw->vma; 3038 struct mm_struct *mm = vma->vm_mm; 3039 unsigned long address = pvmw->address; 3040 pmd_t pmdval; 3041 swp_entry_t entry; 3042 pmd_t pmdswp; 3043 3044 if (!(pvmw->pmd && !pvmw->pte)) 3045 return; 3046 3047 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3048 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3049 if (pmd_dirty(pmdval)) 3050 set_page_dirty(page); 3051 if (pmd_write(pmdval)) 3052 entry = make_writable_migration_entry(page_to_pfn(page)); 3053 else 3054 entry = make_readable_migration_entry(page_to_pfn(page)); 3055 pmdswp = swp_entry_to_pmd(entry); 3056 if (pmd_soft_dirty(pmdval)) 3057 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3058 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3059 page_remove_rmap(page, vma, true); 3060 put_page(page); 3061 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3062 } 3063 3064 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3065 { 3066 struct vm_area_struct *vma = pvmw->vma; 3067 struct mm_struct *mm = vma->vm_mm; 3068 unsigned long address = pvmw->address; 3069 unsigned long mmun_start = address & HPAGE_PMD_MASK; 3070 pmd_t pmde; 3071 swp_entry_t entry; 3072 3073 if (!(pvmw->pmd && !pvmw->pte)) 3074 return; 3075 3076 entry = pmd_to_swp_entry(*pvmw->pmd); 3077 get_page(new); 3078 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3079 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3080 pmde = pmd_mksoft_dirty(pmde); 3081 if (is_writable_migration_entry(entry)) 3082 pmde = maybe_pmd_mkwrite(pmde, vma); 3083 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3084 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3085 3086 if (PageAnon(new)) 3087 page_add_anon_rmap(new, vma, mmun_start, true); 3088 else 3089 page_add_file_rmap(new, vma, true); 3090 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3091 3092 /* No need to invalidate - it was non-present before */ 3093 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3094 trace_remove_migration_pmd(address, pmd_val(pmde)); 3095 } 3096 #endif 3097