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/coredump.h> 11 #include <linux/sched/numa_balancing.h> 12 #include <linux/highmem.h> 13 #include <linux/hugetlb.h> 14 #include <linux/mmu_notifier.h> 15 #include <linux/rmap.h> 16 #include <linux/swap.h> 17 #include <linux/shrinker.h> 18 #include <linux/mm_inline.h> 19 #include <linux/swapops.h> 20 #include <linux/dax.h> 21 #include <linux/khugepaged.h> 22 #include <linux/freezer.h> 23 #include <linux/pfn_t.h> 24 #include <linux/mman.h> 25 #include <linux/memremap.h> 26 #include <linux/pagemap.h> 27 #include <linux/debugfs.h> 28 #include <linux/migrate.h> 29 #include <linux/hashtable.h> 30 #include <linux/userfaultfd_k.h> 31 #include <linux/page_idle.h> 32 #include <linux/shmem_fs.h> 33 #include <linux/oom.h> 34 #include <linux/numa.h> 35 36 #include <asm/tlb.h> 37 #include <asm/pgalloc.h> 38 #include "internal.h" 39 40 /* 41 * By default, transparent hugepage support is disabled in order to avoid 42 * risking an increased memory footprint for applications that are not 43 * guaranteed to benefit from it. When transparent hugepage support is 44 * enabled, it is for all mappings, and khugepaged scans all mappings. 45 * Defrag is invoked by khugepaged hugepage allocations and by page faults 46 * for all hugepage allocations. 47 */ 48 unsigned long transparent_hugepage_flags __read_mostly = 49 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 50 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 51 #endif 52 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 53 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 54 #endif 55 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 57 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 58 59 static struct shrinker deferred_split_shrinker; 60 61 static atomic_t huge_zero_refcount; 62 struct page *huge_zero_page __read_mostly; 63 64 bool transparent_hugepage_enabled(struct vm_area_struct *vma) 65 { 66 if (vma_is_anonymous(vma)) 67 return __transparent_hugepage_enabled(vma); 68 if (vma_is_shmem(vma) && shmem_huge_enabled(vma)) 69 return __transparent_hugepage_enabled(vma); 70 71 return false; 72 } 73 74 static struct page *get_huge_zero_page(void) 75 { 76 struct page *zero_page; 77 retry: 78 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 79 return READ_ONCE(huge_zero_page); 80 81 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 82 HPAGE_PMD_ORDER); 83 if (!zero_page) { 84 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 85 return NULL; 86 } 87 count_vm_event(THP_ZERO_PAGE_ALLOC); 88 preempt_disable(); 89 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 90 preempt_enable(); 91 __free_pages(zero_page, compound_order(zero_page)); 92 goto retry; 93 } 94 95 /* We take additional reference here. It will be put back by shrinker */ 96 atomic_set(&huge_zero_refcount, 2); 97 preempt_enable(); 98 return READ_ONCE(huge_zero_page); 99 } 100 101 static void put_huge_zero_page(void) 102 { 103 /* 104 * Counter should never go to zero here. Only shrinker can put 105 * last reference. 106 */ 107 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 108 } 109 110 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 111 { 112 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 113 return READ_ONCE(huge_zero_page); 114 115 if (!get_huge_zero_page()) 116 return NULL; 117 118 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 119 put_huge_zero_page(); 120 121 return READ_ONCE(huge_zero_page); 122 } 123 124 void mm_put_huge_zero_page(struct mm_struct *mm) 125 { 126 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 127 put_huge_zero_page(); 128 } 129 130 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 131 struct shrink_control *sc) 132 { 133 /* we can free zero page only if last reference remains */ 134 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 135 } 136 137 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 138 struct shrink_control *sc) 139 { 140 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 141 struct page *zero_page = xchg(&huge_zero_page, NULL); 142 BUG_ON(zero_page == NULL); 143 __free_pages(zero_page, compound_order(zero_page)); 144 return HPAGE_PMD_NR; 145 } 146 147 return 0; 148 } 149 150 static struct shrinker huge_zero_page_shrinker = { 151 .count_objects = shrink_huge_zero_page_count, 152 .scan_objects = shrink_huge_zero_page_scan, 153 .seeks = DEFAULT_SEEKS, 154 }; 155 156 #ifdef CONFIG_SYSFS 157 static ssize_t enabled_show(struct kobject *kobj, 158 struct kobj_attribute *attr, char *buf) 159 { 160 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 161 return sprintf(buf, "[always] madvise never\n"); 162 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) 163 return sprintf(buf, "always [madvise] never\n"); 164 else 165 return sprintf(buf, "always madvise [never]\n"); 166 } 167 168 static ssize_t enabled_store(struct kobject *kobj, 169 struct kobj_attribute *attr, 170 const char *buf, size_t count) 171 { 172 ssize_t ret = count; 173 174 if (!memcmp("always", buf, 175 min(sizeof("always")-1, count))) { 176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 177 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 178 } else if (!memcmp("madvise", buf, 179 min(sizeof("madvise")-1, count))) { 180 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 181 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 182 } else if (!memcmp("never", buf, 183 min(sizeof("never")-1, count))) { 184 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 185 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 186 } else 187 ret = -EINVAL; 188 189 if (ret > 0) { 190 int err = start_stop_khugepaged(); 191 if (err) 192 ret = err; 193 } 194 return ret; 195 } 196 static struct kobj_attribute enabled_attr = 197 __ATTR(enabled, 0644, enabled_show, enabled_store); 198 199 ssize_t single_hugepage_flag_show(struct kobject *kobj, 200 struct kobj_attribute *attr, char *buf, 201 enum transparent_hugepage_flag flag) 202 { 203 return sprintf(buf, "%d\n", 204 !!test_bit(flag, &transparent_hugepage_flags)); 205 } 206 207 ssize_t single_hugepage_flag_store(struct kobject *kobj, 208 struct kobj_attribute *attr, 209 const char *buf, size_t count, 210 enum transparent_hugepage_flag flag) 211 { 212 unsigned long value; 213 int ret; 214 215 ret = kstrtoul(buf, 10, &value); 216 if (ret < 0) 217 return ret; 218 if (value > 1) 219 return -EINVAL; 220 221 if (value) 222 set_bit(flag, &transparent_hugepage_flags); 223 else 224 clear_bit(flag, &transparent_hugepage_flags); 225 226 return count; 227 } 228 229 static ssize_t defrag_show(struct kobject *kobj, 230 struct kobj_attribute *attr, char *buf) 231 { 232 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 233 return sprintf(buf, "[always] defer defer+madvise madvise never\n"); 234 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 235 return sprintf(buf, "always [defer] defer+madvise madvise never\n"); 236 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 237 return sprintf(buf, "always defer [defer+madvise] madvise never\n"); 238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 239 return sprintf(buf, "always defer defer+madvise [madvise] never\n"); 240 return sprintf(buf, "always defer defer+madvise madvise [never]\n"); 241 } 242 243 static ssize_t defrag_store(struct kobject *kobj, 244 struct kobj_attribute *attr, 245 const char *buf, size_t count) 246 { 247 if (!memcmp("always", buf, 248 min(sizeof("always")-1, count))) { 249 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 250 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 252 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 253 } else if (!memcmp("defer+madvise", buf, 254 min(sizeof("defer+madvise")-1, count))) { 255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 259 } else if (!memcmp("defer", buf, 260 min(sizeof("defer")-1, count))) { 261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 265 } else if (!memcmp("madvise", buf, 266 min(sizeof("madvise")-1, count))) { 267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 271 } else if (!memcmp("never", buf, 272 min(sizeof("never")-1, count))) { 273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 277 } else 278 return -EINVAL; 279 280 return count; 281 } 282 static struct kobj_attribute defrag_attr = 283 __ATTR(defrag, 0644, defrag_show, defrag_store); 284 285 static ssize_t use_zero_page_show(struct kobject *kobj, 286 struct kobj_attribute *attr, char *buf) 287 { 288 return single_hugepage_flag_show(kobj, attr, buf, 289 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 290 } 291 static ssize_t use_zero_page_store(struct kobject *kobj, 292 struct kobj_attribute *attr, const char *buf, size_t count) 293 { 294 return single_hugepage_flag_store(kobj, attr, buf, count, 295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 296 } 297 static struct kobj_attribute use_zero_page_attr = 298 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 299 300 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 301 struct kobj_attribute *attr, char *buf) 302 { 303 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); 304 } 305 static struct kobj_attribute hpage_pmd_size_attr = 306 __ATTR_RO(hpage_pmd_size); 307 308 #ifdef CONFIG_DEBUG_VM 309 static ssize_t debug_cow_show(struct kobject *kobj, 310 struct kobj_attribute *attr, char *buf) 311 { 312 return single_hugepage_flag_show(kobj, attr, buf, 313 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 314 } 315 static ssize_t debug_cow_store(struct kobject *kobj, 316 struct kobj_attribute *attr, 317 const char *buf, size_t count) 318 { 319 return single_hugepage_flag_store(kobj, attr, buf, count, 320 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 321 } 322 static struct kobj_attribute debug_cow_attr = 323 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); 324 #endif /* CONFIG_DEBUG_VM */ 325 326 static struct attribute *hugepage_attr[] = { 327 &enabled_attr.attr, 328 &defrag_attr.attr, 329 &use_zero_page_attr.attr, 330 &hpage_pmd_size_attr.attr, 331 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) 332 &shmem_enabled_attr.attr, 333 #endif 334 #ifdef CONFIG_DEBUG_VM 335 &debug_cow_attr.attr, 336 #endif 337 NULL, 338 }; 339 340 static const struct attribute_group hugepage_attr_group = { 341 .attrs = hugepage_attr, 342 }; 343 344 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 345 { 346 int err; 347 348 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 349 if (unlikely(!*hugepage_kobj)) { 350 pr_err("failed to create transparent hugepage kobject\n"); 351 return -ENOMEM; 352 } 353 354 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 355 if (err) { 356 pr_err("failed to register transparent hugepage group\n"); 357 goto delete_obj; 358 } 359 360 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 361 if (err) { 362 pr_err("failed to register transparent hugepage group\n"); 363 goto remove_hp_group; 364 } 365 366 return 0; 367 368 remove_hp_group: 369 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 370 delete_obj: 371 kobject_put(*hugepage_kobj); 372 return err; 373 } 374 375 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 376 { 377 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 378 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 379 kobject_put(hugepage_kobj); 380 } 381 #else 382 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 383 { 384 return 0; 385 } 386 387 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 388 { 389 } 390 #endif /* CONFIG_SYSFS */ 391 392 static int __init hugepage_init(void) 393 { 394 int err; 395 struct kobject *hugepage_kobj; 396 397 if (!has_transparent_hugepage()) { 398 transparent_hugepage_flags = 0; 399 return -EINVAL; 400 } 401 402 /* 403 * hugepages can't be allocated by the buddy allocator 404 */ 405 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 406 /* 407 * we use page->mapping and page->index in second tail page 408 * as list_head: assuming THP order >= 2 409 */ 410 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 411 412 err = hugepage_init_sysfs(&hugepage_kobj); 413 if (err) 414 goto err_sysfs; 415 416 err = khugepaged_init(); 417 if (err) 418 goto err_slab; 419 420 err = register_shrinker(&huge_zero_page_shrinker); 421 if (err) 422 goto err_hzp_shrinker; 423 err = register_shrinker(&deferred_split_shrinker); 424 if (err) 425 goto err_split_shrinker; 426 427 /* 428 * By default disable transparent hugepages on smaller systems, 429 * where the extra memory used could hurt more than TLB overhead 430 * is likely to save. The admin can still enable it through /sys. 431 */ 432 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 433 transparent_hugepage_flags = 0; 434 return 0; 435 } 436 437 err = start_stop_khugepaged(); 438 if (err) 439 goto err_khugepaged; 440 441 return 0; 442 err_khugepaged: 443 unregister_shrinker(&deferred_split_shrinker); 444 err_split_shrinker: 445 unregister_shrinker(&huge_zero_page_shrinker); 446 err_hzp_shrinker: 447 khugepaged_destroy(); 448 err_slab: 449 hugepage_exit_sysfs(hugepage_kobj); 450 err_sysfs: 451 return err; 452 } 453 subsys_initcall(hugepage_init); 454 455 static int __init setup_transparent_hugepage(char *str) 456 { 457 int ret = 0; 458 if (!str) 459 goto out; 460 if (!strcmp(str, "always")) { 461 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 462 &transparent_hugepage_flags); 463 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 464 &transparent_hugepage_flags); 465 ret = 1; 466 } else if (!strcmp(str, "madvise")) { 467 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 468 &transparent_hugepage_flags); 469 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 470 &transparent_hugepage_flags); 471 ret = 1; 472 } else if (!strcmp(str, "never")) { 473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 474 &transparent_hugepage_flags); 475 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 476 &transparent_hugepage_flags); 477 ret = 1; 478 } 479 out: 480 if (!ret) 481 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 482 return ret; 483 } 484 __setup("transparent_hugepage=", setup_transparent_hugepage); 485 486 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 487 { 488 if (likely(vma->vm_flags & VM_WRITE)) 489 pmd = pmd_mkwrite(pmd); 490 return pmd; 491 } 492 493 static inline struct list_head *page_deferred_list(struct page *page) 494 { 495 /* ->lru in the tail pages is occupied by compound_head. */ 496 return &page[2].deferred_list; 497 } 498 499 void prep_transhuge_page(struct page *page) 500 { 501 /* 502 * we use page->mapping and page->indexlru in second tail page 503 * as list_head: assuming THP order >= 2 504 */ 505 506 INIT_LIST_HEAD(page_deferred_list(page)); 507 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 508 } 509 510 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, 511 loff_t off, unsigned long flags, unsigned long size) 512 { 513 unsigned long addr; 514 loff_t off_end = off + len; 515 loff_t off_align = round_up(off, size); 516 unsigned long len_pad; 517 518 if (off_end <= off_align || (off_end - off_align) < size) 519 return 0; 520 521 len_pad = len + size; 522 if (len_pad < len || (off + len_pad) < off) 523 return 0; 524 525 addr = current->mm->get_unmapped_area(filp, 0, len_pad, 526 off >> PAGE_SHIFT, flags); 527 if (IS_ERR_VALUE(addr)) 528 return 0; 529 530 addr += (off - addr) & (size - 1); 531 return addr; 532 } 533 534 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 535 unsigned long len, unsigned long pgoff, unsigned long flags) 536 { 537 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 538 539 if (addr) 540 goto out; 541 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) 542 goto out; 543 544 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); 545 if (addr) 546 return addr; 547 548 out: 549 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 550 } 551 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 552 553 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 554 struct page *page, gfp_t gfp) 555 { 556 struct vm_area_struct *vma = vmf->vma; 557 struct mem_cgroup *memcg; 558 pgtable_t pgtable; 559 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 560 vm_fault_t ret = 0; 561 562 VM_BUG_ON_PAGE(!PageCompound(page), page); 563 564 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { 565 put_page(page); 566 count_vm_event(THP_FAULT_FALLBACK); 567 return VM_FAULT_FALLBACK; 568 } 569 570 pgtable = pte_alloc_one(vma->vm_mm); 571 if (unlikely(!pgtable)) { 572 ret = VM_FAULT_OOM; 573 goto release; 574 } 575 576 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 577 /* 578 * The memory barrier inside __SetPageUptodate makes sure that 579 * clear_huge_page writes become visible before the set_pmd_at() 580 * write. 581 */ 582 __SetPageUptodate(page); 583 584 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 585 if (unlikely(!pmd_none(*vmf->pmd))) { 586 goto unlock_release; 587 } else { 588 pmd_t entry; 589 590 ret = check_stable_address_space(vma->vm_mm); 591 if (ret) 592 goto unlock_release; 593 594 /* Deliver the page fault to userland */ 595 if (userfaultfd_missing(vma)) { 596 vm_fault_t ret2; 597 598 spin_unlock(vmf->ptl); 599 mem_cgroup_cancel_charge(page, memcg, true); 600 put_page(page); 601 pte_free(vma->vm_mm, pgtable); 602 ret2 = handle_userfault(vmf, VM_UFFD_MISSING); 603 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); 604 return ret2; 605 } 606 607 entry = mk_huge_pmd(page, vma->vm_page_prot); 608 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 609 page_add_new_anon_rmap(page, vma, haddr, true); 610 mem_cgroup_commit_charge(page, memcg, false, true); 611 lru_cache_add_active_or_unevictable(page, vma); 612 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 613 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 614 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 615 mm_inc_nr_ptes(vma->vm_mm); 616 spin_unlock(vmf->ptl); 617 count_vm_event(THP_FAULT_ALLOC); 618 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 619 } 620 621 return 0; 622 unlock_release: 623 spin_unlock(vmf->ptl); 624 release: 625 if (pgtable) 626 pte_free(vma->vm_mm, pgtable); 627 mem_cgroup_cancel_charge(page, memcg, true); 628 put_page(page); 629 return ret; 630 631 } 632 633 /* 634 * always: directly stall for all thp allocations 635 * defer: wake kswapd and fail if not immediately available 636 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 637 * fail if not immediately available 638 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 639 * available 640 * never: never stall for any thp allocation 641 */ 642 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) 643 { 644 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); 645 646 /* Always do synchronous compaction */ 647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 648 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 649 650 /* Kick kcompactd and fail quickly */ 651 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 652 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 653 654 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 655 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 656 return GFP_TRANSHUGE_LIGHT | 657 (vma_madvised ? __GFP_DIRECT_RECLAIM : 658 __GFP_KSWAPD_RECLAIM); 659 660 /* Only do synchronous compaction if madvised */ 661 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 662 return GFP_TRANSHUGE_LIGHT | 663 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 664 665 return GFP_TRANSHUGE_LIGHT; 666 } 667 668 /* Caller must hold page table lock. */ 669 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 670 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 671 struct page *zero_page) 672 { 673 pmd_t entry; 674 if (!pmd_none(*pmd)) 675 return false; 676 entry = mk_pmd(zero_page, vma->vm_page_prot); 677 entry = pmd_mkhuge(entry); 678 if (pgtable) 679 pgtable_trans_huge_deposit(mm, pmd, pgtable); 680 set_pmd_at(mm, haddr, pmd, entry); 681 mm_inc_nr_ptes(mm); 682 return true; 683 } 684 685 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 686 { 687 struct vm_area_struct *vma = vmf->vma; 688 gfp_t gfp; 689 struct page *page; 690 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 691 692 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) 693 return VM_FAULT_FALLBACK; 694 if (unlikely(anon_vma_prepare(vma))) 695 return VM_FAULT_OOM; 696 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 697 return VM_FAULT_OOM; 698 if (!(vmf->flags & FAULT_FLAG_WRITE) && 699 !mm_forbids_zeropage(vma->vm_mm) && 700 transparent_hugepage_use_zero_page()) { 701 pgtable_t pgtable; 702 struct page *zero_page; 703 bool set; 704 vm_fault_t ret; 705 pgtable = pte_alloc_one(vma->vm_mm); 706 if (unlikely(!pgtable)) 707 return VM_FAULT_OOM; 708 zero_page = mm_get_huge_zero_page(vma->vm_mm); 709 if (unlikely(!zero_page)) { 710 pte_free(vma->vm_mm, pgtable); 711 count_vm_event(THP_FAULT_FALLBACK); 712 return VM_FAULT_FALLBACK; 713 } 714 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 715 ret = 0; 716 set = false; 717 if (pmd_none(*vmf->pmd)) { 718 ret = check_stable_address_space(vma->vm_mm); 719 if (ret) { 720 spin_unlock(vmf->ptl); 721 } else if (userfaultfd_missing(vma)) { 722 spin_unlock(vmf->ptl); 723 ret = handle_userfault(vmf, VM_UFFD_MISSING); 724 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 725 } else { 726 set_huge_zero_page(pgtable, vma->vm_mm, vma, 727 haddr, vmf->pmd, zero_page); 728 spin_unlock(vmf->ptl); 729 set = true; 730 } 731 } else 732 spin_unlock(vmf->ptl); 733 if (!set) 734 pte_free(vma->vm_mm, pgtable); 735 return ret; 736 } 737 gfp = alloc_hugepage_direct_gfpmask(vma); 738 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); 739 if (unlikely(!page)) { 740 count_vm_event(THP_FAULT_FALLBACK); 741 return VM_FAULT_FALLBACK; 742 } 743 prep_transhuge_page(page); 744 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 745 } 746 747 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 748 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 749 pgtable_t pgtable) 750 { 751 struct mm_struct *mm = vma->vm_mm; 752 pmd_t entry; 753 spinlock_t *ptl; 754 755 ptl = pmd_lock(mm, pmd); 756 if (!pmd_none(*pmd)) { 757 if (write) { 758 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 759 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 760 goto out_unlock; 761 } 762 entry = pmd_mkyoung(*pmd); 763 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 764 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 765 update_mmu_cache_pmd(vma, addr, pmd); 766 } 767 768 goto out_unlock; 769 } 770 771 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 772 if (pfn_t_devmap(pfn)) 773 entry = pmd_mkdevmap(entry); 774 if (write) { 775 entry = pmd_mkyoung(pmd_mkdirty(entry)); 776 entry = maybe_pmd_mkwrite(entry, vma); 777 } 778 779 if (pgtable) { 780 pgtable_trans_huge_deposit(mm, pmd, pgtable); 781 mm_inc_nr_ptes(mm); 782 pgtable = NULL; 783 } 784 785 set_pmd_at(mm, addr, pmd, entry); 786 update_mmu_cache_pmd(vma, addr, pmd); 787 788 out_unlock: 789 spin_unlock(ptl); 790 if (pgtable) 791 pte_free(mm, pgtable); 792 } 793 794 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 795 { 796 unsigned long addr = vmf->address & PMD_MASK; 797 struct vm_area_struct *vma = vmf->vma; 798 pgprot_t pgprot = vma->vm_page_prot; 799 pgtable_t pgtable = NULL; 800 801 /* 802 * If we had pmd_special, we could avoid all these restrictions, 803 * but we need to be consistent with PTEs and architectures that 804 * can't support a 'special' bit. 805 */ 806 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 807 !pfn_t_devmap(pfn)); 808 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 809 (VM_PFNMAP|VM_MIXEDMAP)); 810 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 811 812 if (addr < vma->vm_start || addr >= vma->vm_end) 813 return VM_FAULT_SIGBUS; 814 815 if (arch_needs_pgtable_deposit()) { 816 pgtable = pte_alloc_one(vma->vm_mm); 817 if (!pgtable) 818 return VM_FAULT_OOM; 819 } 820 821 track_pfn_insert(vma, &pgprot, pfn); 822 823 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 824 return VM_FAULT_NOPAGE; 825 } 826 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 827 828 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 829 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 830 { 831 if (likely(vma->vm_flags & VM_WRITE)) 832 pud = pud_mkwrite(pud); 833 return pud; 834 } 835 836 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 837 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 838 { 839 struct mm_struct *mm = vma->vm_mm; 840 pud_t entry; 841 spinlock_t *ptl; 842 843 ptl = pud_lock(mm, pud); 844 if (!pud_none(*pud)) { 845 if (write) { 846 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 847 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 848 goto out_unlock; 849 } 850 entry = pud_mkyoung(*pud); 851 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 852 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 853 update_mmu_cache_pud(vma, addr, pud); 854 } 855 goto out_unlock; 856 } 857 858 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 859 if (pfn_t_devmap(pfn)) 860 entry = pud_mkdevmap(entry); 861 if (write) { 862 entry = pud_mkyoung(pud_mkdirty(entry)); 863 entry = maybe_pud_mkwrite(entry, vma); 864 } 865 set_pud_at(mm, addr, pud, entry); 866 update_mmu_cache_pud(vma, addr, pud); 867 868 out_unlock: 869 spin_unlock(ptl); 870 } 871 872 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 873 { 874 unsigned long addr = vmf->address & PUD_MASK; 875 struct vm_area_struct *vma = vmf->vma; 876 pgprot_t pgprot = vma->vm_page_prot; 877 878 /* 879 * If we had pud_special, we could avoid all these restrictions, 880 * but we need to be consistent with PTEs and architectures that 881 * can't support a 'special' bit. 882 */ 883 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 884 !pfn_t_devmap(pfn)); 885 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 886 (VM_PFNMAP|VM_MIXEDMAP)); 887 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 888 889 if (addr < vma->vm_start || addr >= vma->vm_end) 890 return VM_FAULT_SIGBUS; 891 892 track_pfn_insert(vma, &pgprot, pfn); 893 894 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 895 return VM_FAULT_NOPAGE; 896 } 897 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 898 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 899 900 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 901 pmd_t *pmd, int flags) 902 { 903 pmd_t _pmd; 904 905 _pmd = pmd_mkyoung(*pmd); 906 if (flags & FOLL_WRITE) 907 _pmd = pmd_mkdirty(_pmd); 908 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 909 pmd, _pmd, flags & FOLL_WRITE)) 910 update_mmu_cache_pmd(vma, addr, pmd); 911 } 912 913 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 914 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 915 { 916 unsigned long pfn = pmd_pfn(*pmd); 917 struct mm_struct *mm = vma->vm_mm; 918 struct page *page; 919 920 assert_spin_locked(pmd_lockptr(mm, pmd)); 921 922 /* 923 * When we COW a devmap PMD entry, we split it into PTEs, so we should 924 * not be in this function with `flags & FOLL_COW` set. 925 */ 926 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 927 928 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 929 return NULL; 930 931 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 932 /* pass */; 933 else 934 return NULL; 935 936 if (flags & FOLL_TOUCH) 937 touch_pmd(vma, addr, pmd, flags); 938 939 /* 940 * device mapped pages can only be returned if the 941 * caller will manage the page reference count. 942 */ 943 if (!(flags & FOLL_GET)) 944 return ERR_PTR(-EEXIST); 945 946 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 947 *pgmap = get_dev_pagemap(pfn, *pgmap); 948 if (!*pgmap) 949 return ERR_PTR(-EFAULT); 950 page = pfn_to_page(pfn); 951 get_page(page); 952 953 return page; 954 } 955 956 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 957 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 958 struct vm_area_struct *vma) 959 { 960 spinlock_t *dst_ptl, *src_ptl; 961 struct page *src_page; 962 pmd_t pmd; 963 pgtable_t pgtable = NULL; 964 int ret = -ENOMEM; 965 966 /* Skip if can be re-fill on fault */ 967 if (!vma_is_anonymous(vma)) 968 return 0; 969 970 pgtable = pte_alloc_one(dst_mm); 971 if (unlikely(!pgtable)) 972 goto out; 973 974 dst_ptl = pmd_lock(dst_mm, dst_pmd); 975 src_ptl = pmd_lockptr(src_mm, src_pmd); 976 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 977 978 ret = -EAGAIN; 979 pmd = *src_pmd; 980 981 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 982 if (unlikely(is_swap_pmd(pmd))) { 983 swp_entry_t entry = pmd_to_swp_entry(pmd); 984 985 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 986 if (is_write_migration_entry(entry)) { 987 make_migration_entry_read(&entry); 988 pmd = swp_entry_to_pmd(entry); 989 if (pmd_swp_soft_dirty(*src_pmd)) 990 pmd = pmd_swp_mksoft_dirty(pmd); 991 set_pmd_at(src_mm, addr, src_pmd, pmd); 992 } 993 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 994 mm_inc_nr_ptes(dst_mm); 995 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 996 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 997 ret = 0; 998 goto out_unlock; 999 } 1000 #endif 1001 1002 if (unlikely(!pmd_trans_huge(pmd))) { 1003 pte_free(dst_mm, pgtable); 1004 goto out_unlock; 1005 } 1006 /* 1007 * When page table lock is held, the huge zero pmd should not be 1008 * under splitting since we don't split the page itself, only pmd to 1009 * a page table. 1010 */ 1011 if (is_huge_zero_pmd(pmd)) { 1012 struct page *zero_page; 1013 /* 1014 * get_huge_zero_page() will never allocate a new page here, 1015 * since we already have a zero page to copy. It just takes a 1016 * reference. 1017 */ 1018 zero_page = mm_get_huge_zero_page(dst_mm); 1019 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, 1020 zero_page); 1021 ret = 0; 1022 goto out_unlock; 1023 } 1024 1025 src_page = pmd_page(pmd); 1026 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1027 get_page(src_page); 1028 page_dup_rmap(src_page, true); 1029 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1030 mm_inc_nr_ptes(dst_mm); 1031 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1032 1033 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1034 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1035 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1036 1037 ret = 0; 1038 out_unlock: 1039 spin_unlock(src_ptl); 1040 spin_unlock(dst_ptl); 1041 out: 1042 return ret; 1043 } 1044 1045 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1046 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1047 pud_t *pud, int flags) 1048 { 1049 pud_t _pud; 1050 1051 _pud = pud_mkyoung(*pud); 1052 if (flags & FOLL_WRITE) 1053 _pud = pud_mkdirty(_pud); 1054 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1055 pud, _pud, flags & FOLL_WRITE)) 1056 update_mmu_cache_pud(vma, addr, pud); 1057 } 1058 1059 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1060 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1061 { 1062 unsigned long pfn = pud_pfn(*pud); 1063 struct mm_struct *mm = vma->vm_mm; 1064 struct page *page; 1065 1066 assert_spin_locked(pud_lockptr(mm, pud)); 1067 1068 if (flags & FOLL_WRITE && !pud_write(*pud)) 1069 return NULL; 1070 1071 if (pud_present(*pud) && pud_devmap(*pud)) 1072 /* pass */; 1073 else 1074 return NULL; 1075 1076 if (flags & FOLL_TOUCH) 1077 touch_pud(vma, addr, pud, flags); 1078 1079 /* 1080 * device mapped pages can only be returned if the 1081 * caller will manage the page reference count. 1082 */ 1083 if (!(flags & FOLL_GET)) 1084 return ERR_PTR(-EEXIST); 1085 1086 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1087 *pgmap = get_dev_pagemap(pfn, *pgmap); 1088 if (!*pgmap) 1089 return ERR_PTR(-EFAULT); 1090 page = pfn_to_page(pfn); 1091 get_page(page); 1092 1093 return page; 1094 } 1095 1096 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1097 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1098 struct vm_area_struct *vma) 1099 { 1100 spinlock_t *dst_ptl, *src_ptl; 1101 pud_t pud; 1102 int ret; 1103 1104 dst_ptl = pud_lock(dst_mm, dst_pud); 1105 src_ptl = pud_lockptr(src_mm, src_pud); 1106 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1107 1108 ret = -EAGAIN; 1109 pud = *src_pud; 1110 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1111 goto out_unlock; 1112 1113 /* 1114 * When page table lock is held, the huge zero pud should not be 1115 * under splitting since we don't split the page itself, only pud to 1116 * a page table. 1117 */ 1118 if (is_huge_zero_pud(pud)) { 1119 /* No huge zero pud yet */ 1120 } 1121 1122 pudp_set_wrprotect(src_mm, addr, src_pud); 1123 pud = pud_mkold(pud_wrprotect(pud)); 1124 set_pud_at(dst_mm, addr, dst_pud, pud); 1125 1126 ret = 0; 1127 out_unlock: 1128 spin_unlock(src_ptl); 1129 spin_unlock(dst_ptl); 1130 return ret; 1131 } 1132 1133 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1134 { 1135 pud_t entry; 1136 unsigned long haddr; 1137 bool write = vmf->flags & FAULT_FLAG_WRITE; 1138 1139 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1140 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1141 goto unlock; 1142 1143 entry = pud_mkyoung(orig_pud); 1144 if (write) 1145 entry = pud_mkdirty(entry); 1146 haddr = vmf->address & HPAGE_PUD_MASK; 1147 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1148 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1149 1150 unlock: 1151 spin_unlock(vmf->ptl); 1152 } 1153 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1154 1155 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1156 { 1157 pmd_t entry; 1158 unsigned long haddr; 1159 bool write = vmf->flags & FAULT_FLAG_WRITE; 1160 1161 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1162 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1163 goto unlock; 1164 1165 entry = pmd_mkyoung(orig_pmd); 1166 if (write) 1167 entry = pmd_mkdirty(entry); 1168 haddr = vmf->address & HPAGE_PMD_MASK; 1169 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1170 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1171 1172 unlock: 1173 spin_unlock(vmf->ptl); 1174 } 1175 1176 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, 1177 pmd_t orig_pmd, struct page *page) 1178 { 1179 struct vm_area_struct *vma = vmf->vma; 1180 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1181 struct mem_cgroup *memcg; 1182 pgtable_t pgtable; 1183 pmd_t _pmd; 1184 int i; 1185 vm_fault_t ret = 0; 1186 struct page **pages; 1187 struct mmu_notifier_range range; 1188 1189 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), 1190 GFP_KERNEL); 1191 if (unlikely(!pages)) { 1192 ret |= VM_FAULT_OOM; 1193 goto out; 1194 } 1195 1196 for (i = 0; i < HPAGE_PMD_NR; i++) { 1197 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, 1198 vmf->address, page_to_nid(page)); 1199 if (unlikely(!pages[i] || 1200 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, 1201 GFP_KERNEL, &memcg, false))) { 1202 if (pages[i]) 1203 put_page(pages[i]); 1204 while (--i >= 0) { 1205 memcg = (void *)page_private(pages[i]); 1206 set_page_private(pages[i], 0); 1207 mem_cgroup_cancel_charge(pages[i], memcg, 1208 false); 1209 put_page(pages[i]); 1210 } 1211 kfree(pages); 1212 ret |= VM_FAULT_OOM; 1213 goto out; 1214 } 1215 set_page_private(pages[i], (unsigned long)memcg); 1216 } 1217 1218 for (i = 0; i < HPAGE_PMD_NR; i++) { 1219 copy_user_highpage(pages[i], page + i, 1220 haddr + PAGE_SIZE * i, vma); 1221 __SetPageUptodate(pages[i]); 1222 cond_resched(); 1223 } 1224 1225 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1226 haddr, haddr + HPAGE_PMD_SIZE); 1227 mmu_notifier_invalidate_range_start(&range); 1228 1229 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1230 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1231 goto out_free_pages; 1232 VM_BUG_ON_PAGE(!PageHead(page), page); 1233 1234 /* 1235 * Leave pmd empty until pte is filled note we must notify here as 1236 * concurrent CPU thread might write to new page before the call to 1237 * mmu_notifier_invalidate_range_end() happens which can lead to a 1238 * device seeing memory write in different order than CPU. 1239 * 1240 * See Documentation/vm/mmu_notifier.rst 1241 */ 1242 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1243 1244 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); 1245 pmd_populate(vma->vm_mm, &_pmd, pgtable); 1246 1247 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1248 pte_t entry; 1249 entry = mk_pte(pages[i], vma->vm_page_prot); 1250 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1251 memcg = (void *)page_private(pages[i]); 1252 set_page_private(pages[i], 0); 1253 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); 1254 mem_cgroup_commit_charge(pages[i], memcg, false, false); 1255 lru_cache_add_active_or_unevictable(pages[i], vma); 1256 vmf->pte = pte_offset_map(&_pmd, haddr); 1257 VM_BUG_ON(!pte_none(*vmf->pte)); 1258 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); 1259 pte_unmap(vmf->pte); 1260 } 1261 kfree(pages); 1262 1263 smp_wmb(); /* make pte visible before pmd */ 1264 pmd_populate(vma->vm_mm, vmf->pmd, pgtable); 1265 page_remove_rmap(page, true); 1266 spin_unlock(vmf->ptl); 1267 1268 /* 1269 * No need to double call mmu_notifier->invalidate_range() callback as 1270 * the above pmdp_huge_clear_flush_notify() did already call it. 1271 */ 1272 mmu_notifier_invalidate_range_only_end(&range); 1273 1274 ret |= VM_FAULT_WRITE; 1275 put_page(page); 1276 1277 out: 1278 return ret; 1279 1280 out_free_pages: 1281 spin_unlock(vmf->ptl); 1282 mmu_notifier_invalidate_range_end(&range); 1283 for (i = 0; i < HPAGE_PMD_NR; i++) { 1284 memcg = (void *)page_private(pages[i]); 1285 set_page_private(pages[i], 0); 1286 mem_cgroup_cancel_charge(pages[i], memcg, false); 1287 put_page(pages[i]); 1288 } 1289 kfree(pages); 1290 goto out; 1291 } 1292 1293 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1294 { 1295 struct vm_area_struct *vma = vmf->vma; 1296 struct page *page = NULL, *new_page; 1297 struct mem_cgroup *memcg; 1298 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1299 struct mmu_notifier_range range; 1300 gfp_t huge_gfp; /* for allocation and charge */ 1301 vm_fault_t ret = 0; 1302 1303 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1304 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1305 if (is_huge_zero_pmd(orig_pmd)) 1306 goto alloc; 1307 spin_lock(vmf->ptl); 1308 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1309 goto out_unlock; 1310 1311 page = pmd_page(orig_pmd); 1312 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1313 /* 1314 * We can only reuse the page if nobody else maps the huge page or it's 1315 * part. 1316 */ 1317 if (!trylock_page(page)) { 1318 get_page(page); 1319 spin_unlock(vmf->ptl); 1320 lock_page(page); 1321 spin_lock(vmf->ptl); 1322 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1323 unlock_page(page); 1324 put_page(page); 1325 goto out_unlock; 1326 } 1327 put_page(page); 1328 } 1329 if (reuse_swap_page(page, NULL)) { 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 ret |= VM_FAULT_WRITE; 1336 unlock_page(page); 1337 goto out_unlock; 1338 } 1339 unlock_page(page); 1340 get_page(page); 1341 spin_unlock(vmf->ptl); 1342 alloc: 1343 if (__transparent_hugepage_enabled(vma) && 1344 !transparent_hugepage_debug_cow()) { 1345 huge_gfp = alloc_hugepage_direct_gfpmask(vma); 1346 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); 1347 } else 1348 new_page = NULL; 1349 1350 if (likely(new_page)) { 1351 prep_transhuge_page(new_page); 1352 } else { 1353 if (!page) { 1354 split_huge_pmd(vma, vmf->pmd, vmf->address); 1355 ret |= VM_FAULT_FALLBACK; 1356 } else { 1357 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); 1358 if (ret & VM_FAULT_OOM) { 1359 split_huge_pmd(vma, vmf->pmd, vmf->address); 1360 ret |= VM_FAULT_FALLBACK; 1361 } 1362 put_page(page); 1363 } 1364 count_vm_event(THP_FAULT_FALLBACK); 1365 goto out; 1366 } 1367 1368 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, 1369 huge_gfp, &memcg, true))) { 1370 put_page(new_page); 1371 split_huge_pmd(vma, vmf->pmd, vmf->address); 1372 if (page) 1373 put_page(page); 1374 ret |= VM_FAULT_FALLBACK; 1375 count_vm_event(THP_FAULT_FALLBACK); 1376 goto out; 1377 } 1378 1379 count_vm_event(THP_FAULT_ALLOC); 1380 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 1381 1382 if (!page) 1383 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); 1384 else 1385 copy_user_huge_page(new_page, page, vmf->address, 1386 vma, HPAGE_PMD_NR); 1387 __SetPageUptodate(new_page); 1388 1389 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1390 haddr, haddr + HPAGE_PMD_SIZE); 1391 mmu_notifier_invalidate_range_start(&range); 1392 1393 spin_lock(vmf->ptl); 1394 if (page) 1395 put_page(page); 1396 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1397 spin_unlock(vmf->ptl); 1398 mem_cgroup_cancel_charge(new_page, memcg, true); 1399 put_page(new_page); 1400 goto out_mn; 1401 } else { 1402 pmd_t entry; 1403 entry = mk_huge_pmd(new_page, vma->vm_page_prot); 1404 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1405 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1406 page_add_new_anon_rmap(new_page, vma, haddr, true); 1407 mem_cgroup_commit_charge(new_page, memcg, false, true); 1408 lru_cache_add_active_or_unevictable(new_page, vma); 1409 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1410 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1411 if (!page) { 1412 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1413 } else { 1414 VM_BUG_ON_PAGE(!PageHead(page), page); 1415 page_remove_rmap(page, true); 1416 put_page(page); 1417 } 1418 ret |= VM_FAULT_WRITE; 1419 } 1420 spin_unlock(vmf->ptl); 1421 out_mn: 1422 /* 1423 * No need to double call mmu_notifier->invalidate_range() callback as 1424 * the above pmdp_huge_clear_flush_notify() did already call it. 1425 */ 1426 mmu_notifier_invalidate_range_only_end(&range); 1427 out: 1428 return ret; 1429 out_unlock: 1430 spin_unlock(vmf->ptl); 1431 return ret; 1432 } 1433 1434 /* 1435 * FOLL_FORCE can write to even unwritable pmd's, but only 1436 * after we've gone through a COW cycle and they are dirty. 1437 */ 1438 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1439 { 1440 return pmd_write(pmd) || 1441 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1442 } 1443 1444 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1445 unsigned long addr, 1446 pmd_t *pmd, 1447 unsigned int flags) 1448 { 1449 struct mm_struct *mm = vma->vm_mm; 1450 struct page *page = NULL; 1451 1452 assert_spin_locked(pmd_lockptr(mm, pmd)); 1453 1454 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1455 goto out; 1456 1457 /* Avoid dumping huge zero page */ 1458 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1459 return ERR_PTR(-EFAULT); 1460 1461 /* Full NUMA hinting faults to serialise migration in fault paths */ 1462 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1463 goto out; 1464 1465 page = pmd_page(*pmd); 1466 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1467 if (flags & FOLL_TOUCH) 1468 touch_pmd(vma, addr, pmd, flags); 1469 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1470 /* 1471 * We don't mlock() pte-mapped THPs. This way we can avoid 1472 * leaking mlocked pages into non-VM_LOCKED VMAs. 1473 * 1474 * For anon THP: 1475 * 1476 * In most cases the pmd is the only mapping of the page as we 1477 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1478 * writable private mappings in populate_vma_page_range(). 1479 * 1480 * The only scenario when we have the page shared here is if we 1481 * mlocking read-only mapping shared over fork(). We skip 1482 * mlocking such pages. 1483 * 1484 * For file THP: 1485 * 1486 * We can expect PageDoubleMap() to be stable under page lock: 1487 * for file pages we set it in page_add_file_rmap(), which 1488 * requires page to be locked. 1489 */ 1490 1491 if (PageAnon(page) && compound_mapcount(page) != 1) 1492 goto skip_mlock; 1493 if (PageDoubleMap(page) || !page->mapping) 1494 goto skip_mlock; 1495 if (!trylock_page(page)) 1496 goto skip_mlock; 1497 lru_add_drain(); 1498 if (page->mapping && !PageDoubleMap(page)) 1499 mlock_vma_page(page); 1500 unlock_page(page); 1501 } 1502 skip_mlock: 1503 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1504 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1505 if (flags & FOLL_GET) 1506 get_page(page); 1507 1508 out: 1509 return page; 1510 } 1511 1512 /* NUMA hinting page fault entry point for trans huge pmds */ 1513 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1514 { 1515 struct vm_area_struct *vma = vmf->vma; 1516 struct anon_vma *anon_vma = NULL; 1517 struct page *page; 1518 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1519 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1520 int target_nid, last_cpupid = -1; 1521 bool page_locked; 1522 bool migrated = false; 1523 bool was_writable; 1524 int flags = 0; 1525 1526 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1527 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1528 goto out_unlock; 1529 1530 /* 1531 * If there are potential migrations, wait for completion and retry 1532 * without disrupting NUMA hinting information. Do not relock and 1533 * check_same as the page may no longer be mapped. 1534 */ 1535 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1536 page = pmd_page(*vmf->pmd); 1537 if (!get_page_unless_zero(page)) 1538 goto out_unlock; 1539 spin_unlock(vmf->ptl); 1540 put_and_wait_on_page_locked(page); 1541 goto out; 1542 } 1543 1544 page = pmd_page(pmd); 1545 BUG_ON(is_huge_zero_page(page)); 1546 page_nid = page_to_nid(page); 1547 last_cpupid = page_cpupid_last(page); 1548 count_vm_numa_event(NUMA_HINT_FAULTS); 1549 if (page_nid == this_nid) { 1550 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1551 flags |= TNF_FAULT_LOCAL; 1552 } 1553 1554 /* See similar comment in do_numa_page for explanation */ 1555 if (!pmd_savedwrite(pmd)) 1556 flags |= TNF_NO_GROUP; 1557 1558 /* 1559 * Acquire the page lock to serialise THP migrations but avoid dropping 1560 * page_table_lock if at all possible 1561 */ 1562 page_locked = trylock_page(page); 1563 target_nid = mpol_misplaced(page, vma, haddr); 1564 if (target_nid == NUMA_NO_NODE) { 1565 /* If the page was locked, there are no parallel migrations */ 1566 if (page_locked) 1567 goto clear_pmdnuma; 1568 } 1569 1570 /* Migration could have started since the pmd_trans_migrating check */ 1571 if (!page_locked) { 1572 page_nid = NUMA_NO_NODE; 1573 if (!get_page_unless_zero(page)) 1574 goto out_unlock; 1575 spin_unlock(vmf->ptl); 1576 put_and_wait_on_page_locked(page); 1577 goto out; 1578 } 1579 1580 /* 1581 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1582 * to serialises splits 1583 */ 1584 get_page(page); 1585 spin_unlock(vmf->ptl); 1586 anon_vma = page_lock_anon_vma_read(page); 1587 1588 /* Confirm the PMD did not change while page_table_lock was released */ 1589 spin_lock(vmf->ptl); 1590 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1591 unlock_page(page); 1592 put_page(page); 1593 page_nid = NUMA_NO_NODE; 1594 goto out_unlock; 1595 } 1596 1597 /* Bail if we fail to protect against THP splits for any reason */ 1598 if (unlikely(!anon_vma)) { 1599 put_page(page); 1600 page_nid = NUMA_NO_NODE; 1601 goto clear_pmdnuma; 1602 } 1603 1604 /* 1605 * Since we took the NUMA fault, we must have observed the !accessible 1606 * bit. Make sure all other CPUs agree with that, to avoid them 1607 * modifying the page we're about to migrate. 1608 * 1609 * Must be done under PTL such that we'll observe the relevant 1610 * inc_tlb_flush_pending(). 1611 * 1612 * We are not sure a pending tlb flush here is for a huge page 1613 * mapping or not. Hence use the tlb range variant 1614 */ 1615 if (mm_tlb_flush_pending(vma->vm_mm)) { 1616 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1617 /* 1618 * change_huge_pmd() released the pmd lock before 1619 * invalidating the secondary MMUs sharing the primary 1620 * MMU pagetables (with ->invalidate_range()). The 1621 * mmu_notifier_invalidate_range_end() (which 1622 * internally calls ->invalidate_range()) in 1623 * change_pmd_range() will run after us, so we can't 1624 * rely on it here and we need an explicit invalidate. 1625 */ 1626 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1627 haddr + HPAGE_PMD_SIZE); 1628 } 1629 1630 /* 1631 * Migrate the THP to the requested node, returns with page unlocked 1632 * and access rights restored. 1633 */ 1634 spin_unlock(vmf->ptl); 1635 1636 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1637 vmf->pmd, pmd, vmf->address, page, target_nid); 1638 if (migrated) { 1639 flags |= TNF_MIGRATED; 1640 page_nid = target_nid; 1641 } else 1642 flags |= TNF_MIGRATE_FAIL; 1643 1644 goto out; 1645 clear_pmdnuma: 1646 BUG_ON(!PageLocked(page)); 1647 was_writable = pmd_savedwrite(pmd); 1648 pmd = pmd_modify(pmd, vma->vm_page_prot); 1649 pmd = pmd_mkyoung(pmd); 1650 if (was_writable) 1651 pmd = pmd_mkwrite(pmd); 1652 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1653 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1654 unlock_page(page); 1655 out_unlock: 1656 spin_unlock(vmf->ptl); 1657 1658 out: 1659 if (anon_vma) 1660 page_unlock_anon_vma_read(anon_vma); 1661 1662 if (page_nid != NUMA_NO_NODE) 1663 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1664 flags); 1665 1666 return 0; 1667 } 1668 1669 /* 1670 * Return true if we do MADV_FREE successfully on entire pmd page. 1671 * Otherwise, return false. 1672 */ 1673 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1674 pmd_t *pmd, unsigned long addr, unsigned long next) 1675 { 1676 spinlock_t *ptl; 1677 pmd_t orig_pmd; 1678 struct page *page; 1679 struct mm_struct *mm = tlb->mm; 1680 bool ret = false; 1681 1682 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1683 1684 ptl = pmd_trans_huge_lock(pmd, vma); 1685 if (!ptl) 1686 goto out_unlocked; 1687 1688 orig_pmd = *pmd; 1689 if (is_huge_zero_pmd(orig_pmd)) 1690 goto out; 1691 1692 if (unlikely(!pmd_present(orig_pmd))) { 1693 VM_BUG_ON(thp_migration_supported() && 1694 !is_pmd_migration_entry(orig_pmd)); 1695 goto out; 1696 } 1697 1698 page = pmd_page(orig_pmd); 1699 /* 1700 * If other processes are mapping this page, we couldn't discard 1701 * the page unless they all do MADV_FREE so let's skip the page. 1702 */ 1703 if (page_mapcount(page) != 1) 1704 goto out; 1705 1706 if (!trylock_page(page)) 1707 goto out; 1708 1709 /* 1710 * If user want to discard part-pages of THP, split it so MADV_FREE 1711 * will deactivate only them. 1712 */ 1713 if (next - addr != HPAGE_PMD_SIZE) { 1714 get_page(page); 1715 spin_unlock(ptl); 1716 split_huge_page(page); 1717 unlock_page(page); 1718 put_page(page); 1719 goto out_unlocked; 1720 } 1721 1722 if (PageDirty(page)) 1723 ClearPageDirty(page); 1724 unlock_page(page); 1725 1726 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1727 pmdp_invalidate(vma, addr, pmd); 1728 orig_pmd = pmd_mkold(orig_pmd); 1729 orig_pmd = pmd_mkclean(orig_pmd); 1730 1731 set_pmd_at(mm, addr, pmd, orig_pmd); 1732 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1733 } 1734 1735 mark_page_lazyfree(page); 1736 ret = true; 1737 out: 1738 spin_unlock(ptl); 1739 out_unlocked: 1740 return ret; 1741 } 1742 1743 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1744 { 1745 pgtable_t pgtable; 1746 1747 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1748 pte_free(mm, pgtable); 1749 mm_dec_nr_ptes(mm); 1750 } 1751 1752 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1753 pmd_t *pmd, unsigned long addr) 1754 { 1755 pmd_t orig_pmd; 1756 spinlock_t *ptl; 1757 1758 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1759 1760 ptl = __pmd_trans_huge_lock(pmd, vma); 1761 if (!ptl) 1762 return 0; 1763 /* 1764 * For architectures like ppc64 we look at deposited pgtable 1765 * when calling pmdp_huge_get_and_clear. So do the 1766 * pgtable_trans_huge_withdraw after finishing pmdp related 1767 * operations. 1768 */ 1769 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, 1770 tlb->fullmm); 1771 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1772 if (vma_is_dax(vma)) { 1773 if (arch_needs_pgtable_deposit()) 1774 zap_deposited_table(tlb->mm, pmd); 1775 spin_unlock(ptl); 1776 if (is_huge_zero_pmd(orig_pmd)) 1777 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1778 } else if (is_huge_zero_pmd(orig_pmd)) { 1779 zap_deposited_table(tlb->mm, pmd); 1780 spin_unlock(ptl); 1781 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1782 } else { 1783 struct page *page = NULL; 1784 int flush_needed = 1; 1785 1786 if (pmd_present(orig_pmd)) { 1787 page = pmd_page(orig_pmd); 1788 page_remove_rmap(page, true); 1789 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1790 VM_BUG_ON_PAGE(!PageHead(page), page); 1791 } else if (thp_migration_supported()) { 1792 swp_entry_t entry; 1793 1794 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1795 entry = pmd_to_swp_entry(orig_pmd); 1796 page = pfn_to_page(swp_offset(entry)); 1797 flush_needed = 0; 1798 } else 1799 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1800 1801 if (PageAnon(page)) { 1802 zap_deposited_table(tlb->mm, pmd); 1803 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1804 } else { 1805 if (arch_needs_pgtable_deposit()) 1806 zap_deposited_table(tlb->mm, pmd); 1807 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1808 } 1809 1810 spin_unlock(ptl); 1811 if (flush_needed) 1812 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1813 } 1814 return 1; 1815 } 1816 1817 #ifndef pmd_move_must_withdraw 1818 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1819 spinlock_t *old_pmd_ptl, 1820 struct vm_area_struct *vma) 1821 { 1822 /* 1823 * With split pmd lock we also need to move preallocated 1824 * PTE page table if new_pmd is on different PMD page table. 1825 * 1826 * We also don't deposit and withdraw tables for file pages. 1827 */ 1828 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1829 } 1830 #endif 1831 1832 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1833 { 1834 #ifdef CONFIG_MEM_SOFT_DIRTY 1835 if (unlikely(is_pmd_migration_entry(pmd))) 1836 pmd = pmd_swp_mksoft_dirty(pmd); 1837 else if (pmd_present(pmd)) 1838 pmd = pmd_mksoft_dirty(pmd); 1839 #endif 1840 return pmd; 1841 } 1842 1843 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1844 unsigned long new_addr, unsigned long old_end, 1845 pmd_t *old_pmd, pmd_t *new_pmd) 1846 { 1847 spinlock_t *old_ptl, *new_ptl; 1848 pmd_t pmd; 1849 struct mm_struct *mm = vma->vm_mm; 1850 bool force_flush = false; 1851 1852 if ((old_addr & ~HPAGE_PMD_MASK) || 1853 (new_addr & ~HPAGE_PMD_MASK) || 1854 old_end - old_addr < HPAGE_PMD_SIZE) 1855 return false; 1856 1857 /* 1858 * The destination pmd shouldn't be established, free_pgtables() 1859 * should have release it. 1860 */ 1861 if (WARN_ON(!pmd_none(*new_pmd))) { 1862 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1863 return false; 1864 } 1865 1866 /* 1867 * We don't have to worry about the ordering of src and dst 1868 * ptlocks because exclusive mmap_sem prevents deadlock. 1869 */ 1870 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1871 if (old_ptl) { 1872 new_ptl = pmd_lockptr(mm, new_pmd); 1873 if (new_ptl != old_ptl) 1874 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1875 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1876 if (pmd_present(pmd)) 1877 force_flush = true; 1878 VM_BUG_ON(!pmd_none(*new_pmd)); 1879 1880 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1881 pgtable_t pgtable; 1882 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1883 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1884 } 1885 pmd = move_soft_dirty_pmd(pmd); 1886 set_pmd_at(mm, new_addr, new_pmd, pmd); 1887 if (force_flush) 1888 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1889 if (new_ptl != old_ptl) 1890 spin_unlock(new_ptl); 1891 spin_unlock(old_ptl); 1892 return true; 1893 } 1894 return false; 1895 } 1896 1897 /* 1898 * Returns 1899 * - 0 if PMD could not be locked 1900 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1901 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1902 */ 1903 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1904 unsigned long addr, pgprot_t newprot, int prot_numa) 1905 { 1906 struct mm_struct *mm = vma->vm_mm; 1907 spinlock_t *ptl; 1908 pmd_t entry; 1909 bool preserve_write; 1910 int ret; 1911 1912 ptl = __pmd_trans_huge_lock(pmd, vma); 1913 if (!ptl) 1914 return 0; 1915 1916 preserve_write = prot_numa && pmd_write(*pmd); 1917 ret = 1; 1918 1919 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1920 if (is_swap_pmd(*pmd)) { 1921 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1922 1923 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1924 if (is_write_migration_entry(entry)) { 1925 pmd_t newpmd; 1926 /* 1927 * A protection check is difficult so 1928 * just be safe and disable write 1929 */ 1930 make_migration_entry_read(&entry); 1931 newpmd = swp_entry_to_pmd(entry); 1932 if (pmd_swp_soft_dirty(*pmd)) 1933 newpmd = pmd_swp_mksoft_dirty(newpmd); 1934 set_pmd_at(mm, addr, pmd, newpmd); 1935 } 1936 goto unlock; 1937 } 1938 #endif 1939 1940 /* 1941 * Avoid trapping faults against the zero page. The read-only 1942 * data is likely to be read-cached on the local CPU and 1943 * local/remote hits to the zero page are not interesting. 1944 */ 1945 if (prot_numa && is_huge_zero_pmd(*pmd)) 1946 goto unlock; 1947 1948 if (prot_numa && pmd_protnone(*pmd)) 1949 goto unlock; 1950 1951 /* 1952 * In case prot_numa, we are under down_read(mmap_sem). It's critical 1953 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1954 * which is also under down_read(mmap_sem): 1955 * 1956 * CPU0: CPU1: 1957 * change_huge_pmd(prot_numa=1) 1958 * pmdp_huge_get_and_clear_notify() 1959 * madvise_dontneed() 1960 * zap_pmd_range() 1961 * pmd_trans_huge(*pmd) == 0 (without ptl) 1962 * // skip the pmd 1963 * set_pmd_at(); 1964 * // pmd is re-established 1965 * 1966 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1967 * which may break userspace. 1968 * 1969 * pmdp_invalidate() is required to make sure we don't miss 1970 * dirty/young flags set by hardware. 1971 */ 1972 entry = pmdp_invalidate(vma, addr, pmd); 1973 1974 entry = pmd_modify(entry, newprot); 1975 if (preserve_write) 1976 entry = pmd_mk_savedwrite(entry); 1977 ret = HPAGE_PMD_NR; 1978 set_pmd_at(mm, addr, pmd, entry); 1979 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1980 unlock: 1981 spin_unlock(ptl); 1982 return ret; 1983 } 1984 1985 /* 1986 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1987 * 1988 * Note that if it returns page table lock pointer, this routine returns without 1989 * unlocking page table lock. So callers must unlock it. 1990 */ 1991 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1992 { 1993 spinlock_t *ptl; 1994 ptl = pmd_lock(vma->vm_mm, pmd); 1995 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1996 pmd_devmap(*pmd))) 1997 return ptl; 1998 spin_unlock(ptl); 1999 return NULL; 2000 } 2001 2002 /* 2003 * Returns true if a given pud maps a thp, false otherwise. 2004 * 2005 * Note that if it returns true, this routine returns without unlocking page 2006 * table lock. So callers must unlock it. 2007 */ 2008 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2009 { 2010 spinlock_t *ptl; 2011 2012 ptl = pud_lock(vma->vm_mm, pud); 2013 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2014 return ptl; 2015 spin_unlock(ptl); 2016 return NULL; 2017 } 2018 2019 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2020 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2021 pud_t *pud, unsigned long addr) 2022 { 2023 spinlock_t *ptl; 2024 2025 ptl = __pud_trans_huge_lock(pud, vma); 2026 if (!ptl) 2027 return 0; 2028 /* 2029 * For architectures like ppc64 we look at deposited pgtable 2030 * when calling pudp_huge_get_and_clear. So do the 2031 * pgtable_trans_huge_withdraw after finishing pudp related 2032 * operations. 2033 */ 2034 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 2035 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2036 if (vma_is_dax(vma)) { 2037 spin_unlock(ptl); 2038 /* No zero page support yet */ 2039 } else { 2040 /* No support for anonymous PUD pages yet */ 2041 BUG(); 2042 } 2043 return 1; 2044 } 2045 2046 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2047 unsigned long haddr) 2048 { 2049 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2050 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2051 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2052 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2053 2054 count_vm_event(THP_SPLIT_PUD); 2055 2056 pudp_huge_clear_flush_notify(vma, haddr, pud); 2057 } 2058 2059 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2060 unsigned long address) 2061 { 2062 spinlock_t *ptl; 2063 struct mmu_notifier_range range; 2064 2065 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2066 address & HPAGE_PUD_MASK, 2067 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2068 mmu_notifier_invalidate_range_start(&range); 2069 ptl = pud_lock(vma->vm_mm, pud); 2070 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2071 goto out; 2072 __split_huge_pud_locked(vma, pud, range.start); 2073 2074 out: 2075 spin_unlock(ptl); 2076 /* 2077 * No need to double call mmu_notifier->invalidate_range() callback as 2078 * the above pudp_huge_clear_flush_notify() did already call it. 2079 */ 2080 mmu_notifier_invalidate_range_only_end(&range); 2081 } 2082 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2083 2084 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2085 unsigned long haddr, pmd_t *pmd) 2086 { 2087 struct mm_struct *mm = vma->vm_mm; 2088 pgtable_t pgtable; 2089 pmd_t _pmd; 2090 int i; 2091 2092 /* 2093 * Leave pmd empty until pte is filled note that it is fine to delay 2094 * notification until mmu_notifier_invalidate_range_end() as we are 2095 * replacing a zero pmd write protected page with a zero pte write 2096 * protected page. 2097 * 2098 * See Documentation/vm/mmu_notifier.rst 2099 */ 2100 pmdp_huge_clear_flush(vma, haddr, pmd); 2101 2102 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2103 pmd_populate(mm, &_pmd, pgtable); 2104 2105 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2106 pte_t *pte, entry; 2107 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2108 entry = pte_mkspecial(entry); 2109 pte = pte_offset_map(&_pmd, haddr); 2110 VM_BUG_ON(!pte_none(*pte)); 2111 set_pte_at(mm, haddr, pte, entry); 2112 pte_unmap(pte); 2113 } 2114 smp_wmb(); /* make pte visible before pmd */ 2115 pmd_populate(mm, pmd, pgtable); 2116 } 2117 2118 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2119 unsigned long haddr, bool freeze) 2120 { 2121 struct mm_struct *mm = vma->vm_mm; 2122 struct page *page; 2123 pgtable_t pgtable; 2124 pmd_t old_pmd, _pmd; 2125 bool young, write, soft_dirty, pmd_migration = false; 2126 unsigned long addr; 2127 int i; 2128 2129 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2130 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2131 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2132 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2133 && !pmd_devmap(*pmd)); 2134 2135 count_vm_event(THP_SPLIT_PMD); 2136 2137 if (!vma_is_anonymous(vma)) { 2138 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2139 /* 2140 * We are going to unmap this huge page. So 2141 * just go ahead and zap it 2142 */ 2143 if (arch_needs_pgtable_deposit()) 2144 zap_deposited_table(mm, pmd); 2145 if (vma_is_dax(vma)) 2146 return; 2147 page = pmd_page(_pmd); 2148 if (!PageDirty(page) && pmd_dirty(_pmd)) 2149 set_page_dirty(page); 2150 if (!PageReferenced(page) && pmd_young(_pmd)) 2151 SetPageReferenced(page); 2152 page_remove_rmap(page, true); 2153 put_page(page); 2154 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2155 return; 2156 } else if (is_huge_zero_pmd(*pmd)) { 2157 /* 2158 * FIXME: Do we want to invalidate secondary mmu by calling 2159 * mmu_notifier_invalidate_range() see comments below inside 2160 * __split_huge_pmd() ? 2161 * 2162 * We are going from a zero huge page write protected to zero 2163 * small page also write protected so it does not seems useful 2164 * to invalidate secondary mmu at this time. 2165 */ 2166 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2167 } 2168 2169 /* 2170 * Up to this point the pmd is present and huge and userland has the 2171 * whole access to the hugepage during the split (which happens in 2172 * place). If we overwrite the pmd with the not-huge version pointing 2173 * to the pte here (which of course we could if all CPUs were bug 2174 * free), userland could trigger a small page size TLB miss on the 2175 * small sized TLB while the hugepage TLB entry is still established in 2176 * the huge TLB. Some CPU doesn't like that. 2177 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum 2178 * 383 on page 93. Intel should be safe but is also warns that it's 2179 * only safe if the permission and cache attributes of the two entries 2180 * loaded in the two TLB is identical (which should be the case here). 2181 * But it is generally safer to never allow small and huge TLB entries 2182 * for the same virtual address to be loaded simultaneously. So instead 2183 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2184 * current pmd notpresent (atomically because here the pmd_trans_huge 2185 * must remain set at all times on the pmd until the split is complete 2186 * for this pmd), then we flush the SMP TLB and finally we write the 2187 * non-huge version of the pmd entry with pmd_populate. 2188 */ 2189 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2190 2191 pmd_migration = is_pmd_migration_entry(old_pmd); 2192 if (unlikely(pmd_migration)) { 2193 swp_entry_t entry; 2194 2195 entry = pmd_to_swp_entry(old_pmd); 2196 page = pfn_to_page(swp_offset(entry)); 2197 write = is_write_migration_entry(entry); 2198 young = false; 2199 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2200 } else { 2201 page = pmd_page(old_pmd); 2202 if (pmd_dirty(old_pmd)) 2203 SetPageDirty(page); 2204 write = pmd_write(old_pmd); 2205 young = pmd_young(old_pmd); 2206 soft_dirty = pmd_soft_dirty(old_pmd); 2207 } 2208 VM_BUG_ON_PAGE(!page_count(page), page); 2209 page_ref_add(page, HPAGE_PMD_NR - 1); 2210 2211 /* 2212 * Withdraw the table only after we mark the pmd entry invalid. 2213 * This's critical for some architectures (Power). 2214 */ 2215 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2216 pmd_populate(mm, &_pmd, pgtable); 2217 2218 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2219 pte_t entry, *pte; 2220 /* 2221 * Note that NUMA hinting access restrictions are not 2222 * transferred to avoid any possibility of altering 2223 * permissions across VMAs. 2224 */ 2225 if (freeze || pmd_migration) { 2226 swp_entry_t swp_entry; 2227 swp_entry = make_migration_entry(page + i, write); 2228 entry = swp_entry_to_pte(swp_entry); 2229 if (soft_dirty) 2230 entry = pte_swp_mksoft_dirty(entry); 2231 } else { 2232 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2233 entry = maybe_mkwrite(entry, vma); 2234 if (!write) 2235 entry = pte_wrprotect(entry); 2236 if (!young) 2237 entry = pte_mkold(entry); 2238 if (soft_dirty) 2239 entry = pte_mksoft_dirty(entry); 2240 } 2241 pte = pte_offset_map(&_pmd, addr); 2242 BUG_ON(!pte_none(*pte)); 2243 set_pte_at(mm, addr, pte, entry); 2244 atomic_inc(&page[i]._mapcount); 2245 pte_unmap(pte); 2246 } 2247 2248 /* 2249 * Set PG_double_map before dropping compound_mapcount to avoid 2250 * false-negative page_mapped(). 2251 */ 2252 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { 2253 for (i = 0; i < HPAGE_PMD_NR; i++) 2254 atomic_inc(&page[i]._mapcount); 2255 } 2256 2257 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2258 /* Last compound_mapcount is gone. */ 2259 __dec_node_page_state(page, NR_ANON_THPS); 2260 if (TestClearPageDoubleMap(page)) { 2261 /* No need in mapcount reference anymore */ 2262 for (i = 0; i < HPAGE_PMD_NR; i++) 2263 atomic_dec(&page[i]._mapcount); 2264 } 2265 } 2266 2267 smp_wmb(); /* make pte visible before pmd */ 2268 pmd_populate(mm, pmd, pgtable); 2269 2270 if (freeze) { 2271 for (i = 0; i < HPAGE_PMD_NR; i++) { 2272 page_remove_rmap(page + i, false); 2273 put_page(page + i); 2274 } 2275 } 2276 } 2277 2278 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2279 unsigned long address, bool freeze, struct page *page) 2280 { 2281 spinlock_t *ptl; 2282 struct mmu_notifier_range range; 2283 2284 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2285 address & HPAGE_PMD_MASK, 2286 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2287 mmu_notifier_invalidate_range_start(&range); 2288 ptl = pmd_lock(vma->vm_mm, pmd); 2289 2290 /* 2291 * If caller asks to setup a migration entries, we need a page to check 2292 * pmd against. Otherwise we can end up replacing wrong page. 2293 */ 2294 VM_BUG_ON(freeze && !page); 2295 if (page && page != pmd_page(*pmd)) 2296 goto out; 2297 2298 if (pmd_trans_huge(*pmd)) { 2299 page = pmd_page(*pmd); 2300 if (PageMlocked(page)) 2301 clear_page_mlock(page); 2302 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2303 goto out; 2304 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2305 out: 2306 spin_unlock(ptl); 2307 /* 2308 * No need to double call mmu_notifier->invalidate_range() callback. 2309 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2310 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2311 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2312 * fault will trigger a flush_notify before pointing to a new page 2313 * (it is fine if the secondary mmu keeps pointing to the old zero 2314 * page in the meantime) 2315 * 3) Split a huge pmd into pte pointing to the same page. No need 2316 * to invalidate secondary tlb entry they are all still valid. 2317 * any further changes to individual pte will notify. So no need 2318 * to call mmu_notifier->invalidate_range() 2319 */ 2320 mmu_notifier_invalidate_range_only_end(&range); 2321 } 2322 2323 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2324 bool freeze, struct page *page) 2325 { 2326 pgd_t *pgd; 2327 p4d_t *p4d; 2328 pud_t *pud; 2329 pmd_t *pmd; 2330 2331 pgd = pgd_offset(vma->vm_mm, address); 2332 if (!pgd_present(*pgd)) 2333 return; 2334 2335 p4d = p4d_offset(pgd, address); 2336 if (!p4d_present(*p4d)) 2337 return; 2338 2339 pud = pud_offset(p4d, address); 2340 if (!pud_present(*pud)) 2341 return; 2342 2343 pmd = pmd_offset(pud, address); 2344 2345 __split_huge_pmd(vma, pmd, address, freeze, page); 2346 } 2347 2348 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2349 unsigned long start, 2350 unsigned long end, 2351 long adjust_next) 2352 { 2353 /* 2354 * If the new start address isn't hpage aligned and it could 2355 * previously contain an hugepage: check if we need to split 2356 * an huge pmd. 2357 */ 2358 if (start & ~HPAGE_PMD_MASK && 2359 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2360 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2361 split_huge_pmd_address(vma, start, false, NULL); 2362 2363 /* 2364 * If the new end address isn't hpage aligned and it could 2365 * previously contain an hugepage: check if we need to split 2366 * an huge pmd. 2367 */ 2368 if (end & ~HPAGE_PMD_MASK && 2369 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2370 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2371 split_huge_pmd_address(vma, end, false, NULL); 2372 2373 /* 2374 * If we're also updating the vma->vm_next->vm_start, if the new 2375 * vm_next->vm_start isn't page aligned and it could previously 2376 * contain an hugepage: check if we need to split an huge pmd. 2377 */ 2378 if (adjust_next > 0) { 2379 struct vm_area_struct *next = vma->vm_next; 2380 unsigned long nstart = next->vm_start; 2381 nstart += adjust_next << PAGE_SHIFT; 2382 if (nstart & ~HPAGE_PMD_MASK && 2383 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2384 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2385 split_huge_pmd_address(next, nstart, false, NULL); 2386 } 2387 } 2388 2389 static void unmap_page(struct page *page) 2390 { 2391 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | 2392 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2393 bool unmap_success; 2394 2395 VM_BUG_ON_PAGE(!PageHead(page), page); 2396 2397 if (PageAnon(page)) 2398 ttu_flags |= TTU_SPLIT_FREEZE; 2399 2400 unmap_success = try_to_unmap(page, ttu_flags); 2401 VM_BUG_ON_PAGE(!unmap_success, page); 2402 } 2403 2404 static void remap_page(struct page *page) 2405 { 2406 int i; 2407 if (PageTransHuge(page)) { 2408 remove_migration_ptes(page, page, true); 2409 } else { 2410 for (i = 0; i < HPAGE_PMD_NR; i++) 2411 remove_migration_ptes(page + i, page + i, true); 2412 } 2413 } 2414 2415 static void __split_huge_page_tail(struct page *head, int tail, 2416 struct lruvec *lruvec, struct list_head *list) 2417 { 2418 struct page *page_tail = head + tail; 2419 2420 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2421 2422 /* 2423 * Clone page flags before unfreezing refcount. 2424 * 2425 * After successful get_page_unless_zero() might follow flags change, 2426 * for exmaple lock_page() which set PG_waiters. 2427 */ 2428 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2429 page_tail->flags |= (head->flags & 2430 ((1L << PG_referenced) | 2431 (1L << PG_swapbacked) | 2432 (1L << PG_swapcache) | 2433 (1L << PG_mlocked) | 2434 (1L << PG_uptodate) | 2435 (1L << PG_active) | 2436 (1L << PG_workingset) | 2437 (1L << PG_locked) | 2438 (1L << PG_unevictable) | 2439 (1L << PG_dirty))); 2440 2441 /* ->mapping in first tail page is compound_mapcount */ 2442 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2443 page_tail); 2444 page_tail->mapping = head->mapping; 2445 page_tail->index = head->index + tail; 2446 2447 /* Page flags must be visible before we make the page non-compound. */ 2448 smp_wmb(); 2449 2450 /* 2451 * Clear PageTail before unfreezing page refcount. 2452 * 2453 * After successful get_page_unless_zero() might follow put_page() 2454 * which needs correct compound_head(). 2455 */ 2456 clear_compound_head(page_tail); 2457 2458 /* Finally unfreeze refcount. Additional reference from page cache. */ 2459 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2460 PageSwapCache(head))); 2461 2462 if (page_is_young(head)) 2463 set_page_young(page_tail); 2464 if (page_is_idle(head)) 2465 set_page_idle(page_tail); 2466 2467 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2468 2469 /* 2470 * always add to the tail because some iterators expect new 2471 * pages to show after the currently processed elements - e.g. 2472 * migrate_pages 2473 */ 2474 lru_add_page_tail(head, page_tail, lruvec, list); 2475 } 2476 2477 static void __split_huge_page(struct page *page, struct list_head *list, 2478 pgoff_t end, unsigned long flags) 2479 { 2480 struct page *head = compound_head(page); 2481 pg_data_t *pgdat = page_pgdat(head); 2482 struct lruvec *lruvec; 2483 int i; 2484 2485 lruvec = mem_cgroup_page_lruvec(head, pgdat); 2486 2487 /* complete memcg works before add pages to LRU */ 2488 mem_cgroup_split_huge_fixup(head); 2489 2490 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { 2491 __split_huge_page_tail(head, i, lruvec, list); 2492 /* Some pages can be beyond i_size: drop them from page cache */ 2493 if (head[i].index >= end) { 2494 ClearPageDirty(head + i); 2495 __delete_from_page_cache(head + i, NULL); 2496 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2497 shmem_uncharge(head->mapping->host, 1); 2498 put_page(head + i); 2499 } else if (!PageAnon(page)) { 2500 __xa_store(&head->mapping->i_pages, head[i].index, 2501 head + i, 0); 2502 } 2503 } 2504 2505 ClearPageCompound(head); 2506 /* See comment in __split_huge_page_tail() */ 2507 if (PageAnon(head)) { 2508 /* Additional pin to swap cache */ 2509 if (PageSwapCache(head)) 2510 page_ref_add(head, 2); 2511 else 2512 page_ref_inc(head); 2513 } else { 2514 /* Additional pin to page cache */ 2515 page_ref_add(head, 2); 2516 xa_unlock(&head->mapping->i_pages); 2517 } 2518 2519 spin_unlock_irqrestore(&pgdat->lru_lock, flags); 2520 2521 remap_page(head); 2522 2523 for (i = 0; i < HPAGE_PMD_NR; i++) { 2524 struct page *subpage = head + i; 2525 if (subpage == page) 2526 continue; 2527 unlock_page(subpage); 2528 2529 /* 2530 * Subpages may be freed if there wasn't any mapping 2531 * like if add_to_swap() is running on a lru page that 2532 * had its mapping zapped. And freeing these pages 2533 * requires taking the lru_lock so we do the put_page 2534 * of the tail pages after the split is complete. 2535 */ 2536 put_page(subpage); 2537 } 2538 } 2539 2540 int total_mapcount(struct page *page) 2541 { 2542 int i, compound, ret; 2543 2544 VM_BUG_ON_PAGE(PageTail(page), page); 2545 2546 if (likely(!PageCompound(page))) 2547 return atomic_read(&page->_mapcount) + 1; 2548 2549 compound = compound_mapcount(page); 2550 if (PageHuge(page)) 2551 return compound; 2552 ret = compound; 2553 for (i = 0; i < HPAGE_PMD_NR; i++) 2554 ret += atomic_read(&page[i]._mapcount) + 1; 2555 /* File pages has compound_mapcount included in _mapcount */ 2556 if (!PageAnon(page)) 2557 return ret - compound * HPAGE_PMD_NR; 2558 if (PageDoubleMap(page)) 2559 ret -= HPAGE_PMD_NR; 2560 return ret; 2561 } 2562 2563 /* 2564 * This calculates accurately how many mappings a transparent hugepage 2565 * has (unlike page_mapcount() which isn't fully accurate). This full 2566 * accuracy is primarily needed to know if copy-on-write faults can 2567 * reuse the page and change the mapping to read-write instead of 2568 * copying them. At the same time this returns the total_mapcount too. 2569 * 2570 * The function returns the highest mapcount any one of the subpages 2571 * has. If the return value is one, even if different processes are 2572 * mapping different subpages of the transparent hugepage, they can 2573 * all reuse it, because each process is reusing a different subpage. 2574 * 2575 * The total_mapcount is instead counting all virtual mappings of the 2576 * subpages. If the total_mapcount is equal to "one", it tells the 2577 * caller all mappings belong to the same "mm" and in turn the 2578 * anon_vma of the transparent hugepage can become the vma->anon_vma 2579 * local one as no other process may be mapping any of the subpages. 2580 * 2581 * It would be more accurate to replace page_mapcount() with 2582 * page_trans_huge_mapcount(), however we only use 2583 * page_trans_huge_mapcount() in the copy-on-write faults where we 2584 * need full accuracy to avoid breaking page pinning, because 2585 * page_trans_huge_mapcount() is slower than page_mapcount(). 2586 */ 2587 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2588 { 2589 int i, ret, _total_mapcount, mapcount; 2590 2591 /* hugetlbfs shouldn't call it */ 2592 VM_BUG_ON_PAGE(PageHuge(page), page); 2593 2594 if (likely(!PageTransCompound(page))) { 2595 mapcount = atomic_read(&page->_mapcount) + 1; 2596 if (total_mapcount) 2597 *total_mapcount = mapcount; 2598 return mapcount; 2599 } 2600 2601 page = compound_head(page); 2602 2603 _total_mapcount = ret = 0; 2604 for (i = 0; i < HPAGE_PMD_NR; i++) { 2605 mapcount = atomic_read(&page[i]._mapcount) + 1; 2606 ret = max(ret, mapcount); 2607 _total_mapcount += mapcount; 2608 } 2609 if (PageDoubleMap(page)) { 2610 ret -= 1; 2611 _total_mapcount -= HPAGE_PMD_NR; 2612 } 2613 mapcount = compound_mapcount(page); 2614 ret += mapcount; 2615 _total_mapcount += mapcount; 2616 if (total_mapcount) 2617 *total_mapcount = _total_mapcount; 2618 return ret; 2619 } 2620 2621 /* Racy check whether the huge page can be split */ 2622 bool can_split_huge_page(struct page *page, int *pextra_pins) 2623 { 2624 int extra_pins; 2625 2626 /* Additional pins from page cache */ 2627 if (PageAnon(page)) 2628 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; 2629 else 2630 extra_pins = HPAGE_PMD_NR; 2631 if (pextra_pins) 2632 *pextra_pins = extra_pins; 2633 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2634 } 2635 2636 /* 2637 * This function splits huge page into normal pages. @page can point to any 2638 * subpage of huge page to split. Split doesn't change the position of @page. 2639 * 2640 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2641 * The huge page must be locked. 2642 * 2643 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2644 * 2645 * Both head page and tail pages will inherit mapping, flags, and so on from 2646 * the hugepage. 2647 * 2648 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2649 * they are not mapped. 2650 * 2651 * Returns 0 if the hugepage is split successfully. 2652 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2653 * us. 2654 */ 2655 int split_huge_page_to_list(struct page *page, struct list_head *list) 2656 { 2657 struct page *head = compound_head(page); 2658 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); 2659 struct anon_vma *anon_vma = NULL; 2660 struct address_space *mapping = NULL; 2661 int count, mapcount, extra_pins, ret; 2662 bool mlocked; 2663 unsigned long flags; 2664 pgoff_t end; 2665 2666 VM_BUG_ON_PAGE(is_huge_zero_page(page), page); 2667 VM_BUG_ON_PAGE(!PageLocked(page), page); 2668 VM_BUG_ON_PAGE(!PageCompound(page), page); 2669 2670 if (PageWriteback(page)) 2671 return -EBUSY; 2672 2673 if (PageAnon(head)) { 2674 /* 2675 * The caller does not necessarily hold an mmap_sem that would 2676 * prevent the anon_vma disappearing so we first we take a 2677 * reference to it and then lock the anon_vma for write. This 2678 * is similar to page_lock_anon_vma_read except the write lock 2679 * is taken to serialise against parallel split or collapse 2680 * operations. 2681 */ 2682 anon_vma = page_get_anon_vma(head); 2683 if (!anon_vma) { 2684 ret = -EBUSY; 2685 goto out; 2686 } 2687 end = -1; 2688 mapping = NULL; 2689 anon_vma_lock_write(anon_vma); 2690 } else { 2691 mapping = head->mapping; 2692 2693 /* Truncated ? */ 2694 if (!mapping) { 2695 ret = -EBUSY; 2696 goto out; 2697 } 2698 2699 anon_vma = NULL; 2700 i_mmap_lock_read(mapping); 2701 2702 /* 2703 *__split_huge_page() may need to trim off pages beyond EOF: 2704 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2705 * which cannot be nested inside the page tree lock. So note 2706 * end now: i_size itself may be changed at any moment, but 2707 * head page lock is good enough to serialize the trimming. 2708 */ 2709 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2710 } 2711 2712 /* 2713 * Racy check if we can split the page, before unmap_page() will 2714 * split PMDs 2715 */ 2716 if (!can_split_huge_page(head, &extra_pins)) { 2717 ret = -EBUSY; 2718 goto out_unlock; 2719 } 2720 2721 mlocked = PageMlocked(page); 2722 unmap_page(head); 2723 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2724 2725 /* Make sure the page is not on per-CPU pagevec as it takes pin */ 2726 if (mlocked) 2727 lru_add_drain(); 2728 2729 /* prevent PageLRU to go away from under us, and freeze lru stats */ 2730 spin_lock_irqsave(&pgdata->lru_lock, flags); 2731 2732 if (mapping) { 2733 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2734 2735 /* 2736 * Check if the head page is present in page cache. 2737 * We assume all tail are present too, if head is there. 2738 */ 2739 xa_lock(&mapping->i_pages); 2740 if (xas_load(&xas) != head) 2741 goto fail; 2742 } 2743 2744 /* Prevent deferred_split_scan() touching ->_refcount */ 2745 spin_lock(&pgdata->split_queue_lock); 2746 count = page_count(head); 2747 mapcount = total_mapcount(head); 2748 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2749 if (!list_empty(page_deferred_list(head))) { 2750 pgdata->split_queue_len--; 2751 list_del(page_deferred_list(head)); 2752 } 2753 if (mapping) 2754 __dec_node_page_state(page, NR_SHMEM_THPS); 2755 spin_unlock(&pgdata->split_queue_lock); 2756 __split_huge_page(page, list, end, flags); 2757 if (PageSwapCache(head)) { 2758 swp_entry_t entry = { .val = page_private(head) }; 2759 2760 ret = split_swap_cluster(entry); 2761 } else 2762 ret = 0; 2763 } else { 2764 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2765 pr_alert("total_mapcount: %u, page_count(): %u\n", 2766 mapcount, count); 2767 if (PageTail(page)) 2768 dump_page(head, NULL); 2769 dump_page(page, "total_mapcount(head) > 0"); 2770 BUG(); 2771 } 2772 spin_unlock(&pgdata->split_queue_lock); 2773 fail: if (mapping) 2774 xa_unlock(&mapping->i_pages); 2775 spin_unlock_irqrestore(&pgdata->lru_lock, flags); 2776 remap_page(head); 2777 ret = -EBUSY; 2778 } 2779 2780 out_unlock: 2781 if (anon_vma) { 2782 anon_vma_unlock_write(anon_vma); 2783 put_anon_vma(anon_vma); 2784 } 2785 if (mapping) 2786 i_mmap_unlock_read(mapping); 2787 out: 2788 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2789 return ret; 2790 } 2791 2792 void free_transhuge_page(struct page *page) 2793 { 2794 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2795 unsigned long flags; 2796 2797 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2798 if (!list_empty(page_deferred_list(page))) { 2799 pgdata->split_queue_len--; 2800 list_del(page_deferred_list(page)); 2801 } 2802 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2803 free_compound_page(page); 2804 } 2805 2806 void deferred_split_huge_page(struct page *page) 2807 { 2808 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2809 unsigned long flags; 2810 2811 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2812 2813 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2814 if (list_empty(page_deferred_list(page))) { 2815 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2816 list_add_tail(page_deferred_list(page), &pgdata->split_queue); 2817 pgdata->split_queue_len++; 2818 } 2819 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2820 } 2821 2822 static unsigned long deferred_split_count(struct shrinker *shrink, 2823 struct shrink_control *sc) 2824 { 2825 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2826 return READ_ONCE(pgdata->split_queue_len); 2827 } 2828 2829 static unsigned long deferred_split_scan(struct shrinker *shrink, 2830 struct shrink_control *sc) 2831 { 2832 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2833 unsigned long flags; 2834 LIST_HEAD(list), *pos, *next; 2835 struct page *page; 2836 int split = 0; 2837 2838 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2839 /* Take pin on all head pages to avoid freeing them under us */ 2840 list_for_each_safe(pos, next, &pgdata->split_queue) { 2841 page = list_entry((void *)pos, struct page, mapping); 2842 page = compound_head(page); 2843 if (get_page_unless_zero(page)) { 2844 list_move(page_deferred_list(page), &list); 2845 } else { 2846 /* We lost race with put_compound_page() */ 2847 list_del_init(page_deferred_list(page)); 2848 pgdata->split_queue_len--; 2849 } 2850 if (!--sc->nr_to_scan) 2851 break; 2852 } 2853 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2854 2855 list_for_each_safe(pos, next, &list) { 2856 page = list_entry((void *)pos, struct page, mapping); 2857 if (!trylock_page(page)) 2858 goto next; 2859 /* split_huge_page() removes page from list on success */ 2860 if (!split_huge_page(page)) 2861 split++; 2862 unlock_page(page); 2863 next: 2864 put_page(page); 2865 } 2866 2867 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2868 list_splice_tail(&list, &pgdata->split_queue); 2869 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2870 2871 /* 2872 * Stop shrinker if we didn't split any page, but the queue is empty. 2873 * This can happen if pages were freed under us. 2874 */ 2875 if (!split && list_empty(&pgdata->split_queue)) 2876 return SHRINK_STOP; 2877 return split; 2878 } 2879 2880 static struct shrinker deferred_split_shrinker = { 2881 .count_objects = deferred_split_count, 2882 .scan_objects = deferred_split_scan, 2883 .seeks = DEFAULT_SEEKS, 2884 .flags = SHRINKER_NUMA_AWARE, 2885 }; 2886 2887 #ifdef CONFIG_DEBUG_FS 2888 static int split_huge_pages_set(void *data, u64 val) 2889 { 2890 struct zone *zone; 2891 struct page *page; 2892 unsigned long pfn, max_zone_pfn; 2893 unsigned long total = 0, split = 0; 2894 2895 if (val != 1) 2896 return -EINVAL; 2897 2898 for_each_populated_zone(zone) { 2899 max_zone_pfn = zone_end_pfn(zone); 2900 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2901 if (!pfn_valid(pfn)) 2902 continue; 2903 2904 page = pfn_to_page(pfn); 2905 if (!get_page_unless_zero(page)) 2906 continue; 2907 2908 if (zone != page_zone(page)) 2909 goto next; 2910 2911 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2912 goto next; 2913 2914 total++; 2915 lock_page(page); 2916 if (!split_huge_page(page)) 2917 split++; 2918 unlock_page(page); 2919 next: 2920 put_page(page); 2921 } 2922 } 2923 2924 pr_info("%lu of %lu THP split\n", split, total); 2925 2926 return 0; 2927 } 2928 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 2929 "%llu\n"); 2930 2931 static int __init split_huge_pages_debugfs(void) 2932 { 2933 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 2934 &split_huge_pages_fops); 2935 return 0; 2936 } 2937 late_initcall(split_huge_pages_debugfs); 2938 #endif 2939 2940 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2941 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 2942 struct page *page) 2943 { 2944 struct vm_area_struct *vma = pvmw->vma; 2945 struct mm_struct *mm = vma->vm_mm; 2946 unsigned long address = pvmw->address; 2947 pmd_t pmdval; 2948 swp_entry_t entry; 2949 pmd_t pmdswp; 2950 2951 if (!(pvmw->pmd && !pvmw->pte)) 2952 return; 2953 2954 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 2955 pmdval = *pvmw->pmd; 2956 pmdp_invalidate(vma, address, pvmw->pmd); 2957 if (pmd_dirty(pmdval)) 2958 set_page_dirty(page); 2959 entry = make_migration_entry(page, pmd_write(pmdval)); 2960 pmdswp = swp_entry_to_pmd(entry); 2961 if (pmd_soft_dirty(pmdval)) 2962 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 2963 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 2964 page_remove_rmap(page, true); 2965 put_page(page); 2966 } 2967 2968 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 2969 { 2970 struct vm_area_struct *vma = pvmw->vma; 2971 struct mm_struct *mm = vma->vm_mm; 2972 unsigned long address = pvmw->address; 2973 unsigned long mmun_start = address & HPAGE_PMD_MASK; 2974 pmd_t pmde; 2975 swp_entry_t entry; 2976 2977 if (!(pvmw->pmd && !pvmw->pte)) 2978 return; 2979 2980 entry = pmd_to_swp_entry(*pvmw->pmd); 2981 get_page(new); 2982 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 2983 if (pmd_swp_soft_dirty(*pvmw->pmd)) 2984 pmde = pmd_mksoft_dirty(pmde); 2985 if (is_write_migration_entry(entry)) 2986 pmde = maybe_pmd_mkwrite(pmde, vma); 2987 2988 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 2989 if (PageAnon(new)) 2990 page_add_anon_rmap(new, vma, mmun_start, true); 2991 else 2992 page_add_file_rmap(new, true); 2993 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 2994 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 2995 mlock_vma_page(new); 2996 update_mmu_cache_pmd(vma, address, pvmw->pmd); 2997 } 2998 #endif 2999