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 #include <linux/page_owner.h> 36 37 #include <asm/tlb.h> 38 #include <asm/pgalloc.h> 39 #include "internal.h" 40 41 /* 42 * By default, transparent hugepage support is disabled in order to avoid 43 * risking an increased memory footprint for applications that are not 44 * guaranteed to benefit from it. When transparent hugepage support is 45 * enabled, it is for all mappings, and khugepaged scans all mappings. 46 * Defrag is invoked by khugepaged hugepage allocations and by page faults 47 * for all hugepage allocations. 48 */ 49 unsigned long transparent_hugepage_flags __read_mostly = 50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 51 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 52 #endif 53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 55 #endif 56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 59 60 static struct shrinker deferred_split_shrinker; 61 62 static atomic_t huge_zero_refcount; 63 struct page *huge_zero_page __read_mostly; 64 65 bool transparent_hugepage_enabled(struct vm_area_struct *vma) 66 { 67 /* The addr is used to check if the vma size fits */ 68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; 69 70 if (!transhuge_vma_suitable(vma, addr)) 71 return false; 72 if (vma_is_anonymous(vma)) 73 return __transparent_hugepage_enabled(vma); 74 if (vma_is_shmem(vma)) 75 return shmem_huge_enabled(vma); 76 77 return false; 78 } 79 80 static struct page *get_huge_zero_page(void) 81 { 82 struct page *zero_page; 83 retry: 84 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 85 return READ_ONCE(huge_zero_page); 86 87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 88 HPAGE_PMD_ORDER); 89 if (!zero_page) { 90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 91 return NULL; 92 } 93 count_vm_event(THP_ZERO_PAGE_ALLOC); 94 preempt_disable(); 95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 96 preempt_enable(); 97 __free_pages(zero_page, compound_order(zero_page)); 98 goto retry; 99 } 100 101 /* We take additional reference here. It will be put back by shrinker */ 102 atomic_set(&huge_zero_refcount, 2); 103 preempt_enable(); 104 return READ_ONCE(huge_zero_page); 105 } 106 107 static void put_huge_zero_page(void) 108 { 109 /* 110 * Counter should never go to zero here. Only shrinker can put 111 * last reference. 112 */ 113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 114 } 115 116 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 117 { 118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 119 return READ_ONCE(huge_zero_page); 120 121 if (!get_huge_zero_page()) 122 return NULL; 123 124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 125 put_huge_zero_page(); 126 127 return READ_ONCE(huge_zero_page); 128 } 129 130 void mm_put_huge_zero_page(struct mm_struct *mm) 131 { 132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 133 put_huge_zero_page(); 134 } 135 136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 137 struct shrink_control *sc) 138 { 139 /* we can free zero page only if last reference remains */ 140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 141 } 142 143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 144 struct shrink_control *sc) 145 { 146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 147 struct page *zero_page = xchg(&huge_zero_page, NULL); 148 BUG_ON(zero_page == NULL); 149 __free_pages(zero_page, compound_order(zero_page)); 150 return HPAGE_PMD_NR; 151 } 152 153 return 0; 154 } 155 156 static struct shrinker huge_zero_page_shrinker = { 157 .count_objects = shrink_huge_zero_page_count, 158 .scan_objects = shrink_huge_zero_page_scan, 159 .seeks = DEFAULT_SEEKS, 160 }; 161 162 #ifdef CONFIG_SYSFS 163 static ssize_t enabled_show(struct kobject *kobj, 164 struct kobj_attribute *attr, char *buf) 165 { 166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 167 return sprintf(buf, "[always] madvise never\n"); 168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) 169 return sprintf(buf, "always [madvise] never\n"); 170 else 171 return sprintf(buf, "always madvise [never]\n"); 172 } 173 174 static ssize_t enabled_store(struct kobject *kobj, 175 struct kobj_attribute *attr, 176 const char *buf, size_t count) 177 { 178 ssize_t ret = count; 179 180 if (!memcmp("always", buf, 181 min(sizeof("always")-1, count))) { 182 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 183 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 184 } else if (!memcmp("madvise", buf, 185 min(sizeof("madvise")-1, count))) { 186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 187 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 188 } else if (!memcmp("never", buf, 189 min(sizeof("never")-1, count))) { 190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 192 } else 193 ret = -EINVAL; 194 195 if (ret > 0) { 196 int err = start_stop_khugepaged(); 197 if (err) 198 ret = err; 199 } 200 return ret; 201 } 202 static struct kobj_attribute enabled_attr = 203 __ATTR(enabled, 0644, enabled_show, enabled_store); 204 205 ssize_t single_hugepage_flag_show(struct kobject *kobj, 206 struct kobj_attribute *attr, char *buf, 207 enum transparent_hugepage_flag flag) 208 { 209 return sprintf(buf, "%d\n", 210 !!test_bit(flag, &transparent_hugepage_flags)); 211 } 212 213 ssize_t single_hugepage_flag_store(struct kobject *kobj, 214 struct kobj_attribute *attr, 215 const char *buf, size_t count, 216 enum transparent_hugepage_flag flag) 217 { 218 unsigned long value; 219 int ret; 220 221 ret = kstrtoul(buf, 10, &value); 222 if (ret < 0) 223 return ret; 224 if (value > 1) 225 return -EINVAL; 226 227 if (value) 228 set_bit(flag, &transparent_hugepage_flags); 229 else 230 clear_bit(flag, &transparent_hugepage_flags); 231 232 return count; 233 } 234 235 static ssize_t defrag_show(struct kobject *kobj, 236 struct kobj_attribute *attr, char *buf) 237 { 238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 239 return sprintf(buf, "[always] defer defer+madvise madvise never\n"); 240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 241 return sprintf(buf, "always [defer] defer+madvise madvise never\n"); 242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 243 return sprintf(buf, "always defer [defer+madvise] madvise never\n"); 244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 245 return sprintf(buf, "always defer defer+madvise [madvise] never\n"); 246 return sprintf(buf, "always defer defer+madvise madvise [never]\n"); 247 } 248 249 static ssize_t defrag_store(struct kobject *kobj, 250 struct kobj_attribute *attr, 251 const char *buf, size_t count) 252 { 253 if (!memcmp("always", buf, 254 min(sizeof("always")-1, count))) { 255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 259 } else if (!memcmp("defer+madvise", buf, 260 min(sizeof("defer+madvise")-1, count))) { 261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 265 } else if (!memcmp("defer", buf, 266 min(sizeof("defer")-1, count))) { 267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 271 } else if (!memcmp("madvise", buf, 272 min(sizeof("madvise")-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 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 277 } else if (!memcmp("never", buf, 278 min(sizeof("never")-1, count))) { 279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 283 } else 284 return -EINVAL; 285 286 return count; 287 } 288 static struct kobj_attribute defrag_attr = 289 __ATTR(defrag, 0644, defrag_show, defrag_store); 290 291 static ssize_t use_zero_page_show(struct kobject *kobj, 292 struct kobj_attribute *attr, char *buf) 293 { 294 return single_hugepage_flag_show(kobj, attr, buf, 295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 296 } 297 static ssize_t use_zero_page_store(struct kobject *kobj, 298 struct kobj_attribute *attr, const char *buf, size_t count) 299 { 300 return single_hugepage_flag_store(kobj, attr, buf, count, 301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 302 } 303 static struct kobj_attribute use_zero_page_attr = 304 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 305 306 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 307 struct kobj_attribute *attr, char *buf) 308 { 309 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); 310 } 311 static struct kobj_attribute hpage_pmd_size_attr = 312 __ATTR_RO(hpage_pmd_size); 313 314 #ifdef CONFIG_DEBUG_VM 315 static ssize_t debug_cow_show(struct kobject *kobj, 316 struct kobj_attribute *attr, char *buf) 317 { 318 return single_hugepage_flag_show(kobj, attr, buf, 319 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 320 } 321 static ssize_t debug_cow_store(struct kobject *kobj, 322 struct kobj_attribute *attr, 323 const char *buf, size_t count) 324 { 325 return single_hugepage_flag_store(kobj, attr, buf, count, 326 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 327 } 328 static struct kobj_attribute debug_cow_attr = 329 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); 330 #endif /* CONFIG_DEBUG_VM */ 331 332 static struct attribute *hugepage_attr[] = { 333 &enabled_attr.attr, 334 &defrag_attr.attr, 335 &use_zero_page_attr.attr, 336 &hpage_pmd_size_attr.attr, 337 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) 338 &shmem_enabled_attr.attr, 339 #endif 340 #ifdef CONFIG_DEBUG_VM 341 &debug_cow_attr.attr, 342 #endif 343 NULL, 344 }; 345 346 static const struct attribute_group hugepage_attr_group = { 347 .attrs = hugepage_attr, 348 }; 349 350 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 351 { 352 int err; 353 354 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 355 if (unlikely(!*hugepage_kobj)) { 356 pr_err("failed to create transparent hugepage kobject\n"); 357 return -ENOMEM; 358 } 359 360 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 361 if (err) { 362 pr_err("failed to register transparent hugepage group\n"); 363 goto delete_obj; 364 } 365 366 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 367 if (err) { 368 pr_err("failed to register transparent hugepage group\n"); 369 goto remove_hp_group; 370 } 371 372 return 0; 373 374 remove_hp_group: 375 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 376 delete_obj: 377 kobject_put(*hugepage_kobj); 378 return err; 379 } 380 381 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 382 { 383 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 384 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 385 kobject_put(hugepage_kobj); 386 } 387 #else 388 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 389 { 390 return 0; 391 } 392 393 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 394 { 395 } 396 #endif /* CONFIG_SYSFS */ 397 398 static int __init hugepage_init(void) 399 { 400 int err; 401 struct kobject *hugepage_kobj; 402 403 if (!has_transparent_hugepage()) { 404 transparent_hugepage_flags = 0; 405 return -EINVAL; 406 } 407 408 /* 409 * hugepages can't be allocated by the buddy allocator 410 */ 411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 412 /* 413 * we use page->mapping and page->index in second tail page 414 * as list_head: assuming THP order >= 2 415 */ 416 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 417 418 err = hugepage_init_sysfs(&hugepage_kobj); 419 if (err) 420 goto err_sysfs; 421 422 err = khugepaged_init(); 423 if (err) 424 goto err_slab; 425 426 err = register_shrinker(&huge_zero_page_shrinker); 427 if (err) 428 goto err_hzp_shrinker; 429 err = register_shrinker(&deferred_split_shrinker); 430 if (err) 431 goto err_split_shrinker; 432 433 /* 434 * By default disable transparent hugepages on smaller systems, 435 * where the extra memory used could hurt more than TLB overhead 436 * is likely to save. The admin can still enable it through /sys. 437 */ 438 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 439 transparent_hugepage_flags = 0; 440 return 0; 441 } 442 443 err = start_stop_khugepaged(); 444 if (err) 445 goto err_khugepaged; 446 447 return 0; 448 err_khugepaged: 449 unregister_shrinker(&deferred_split_shrinker); 450 err_split_shrinker: 451 unregister_shrinker(&huge_zero_page_shrinker); 452 err_hzp_shrinker: 453 khugepaged_destroy(); 454 err_slab: 455 hugepage_exit_sysfs(hugepage_kobj); 456 err_sysfs: 457 return err; 458 } 459 subsys_initcall(hugepage_init); 460 461 static int __init setup_transparent_hugepage(char *str) 462 { 463 int ret = 0; 464 if (!str) 465 goto out; 466 if (!strcmp(str, "always")) { 467 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 468 &transparent_hugepage_flags); 469 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 470 &transparent_hugepage_flags); 471 ret = 1; 472 } else if (!strcmp(str, "madvise")) { 473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 474 &transparent_hugepage_flags); 475 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 476 &transparent_hugepage_flags); 477 ret = 1; 478 } else if (!strcmp(str, "never")) { 479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 480 &transparent_hugepage_flags); 481 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 482 &transparent_hugepage_flags); 483 ret = 1; 484 } 485 out: 486 if (!ret) 487 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 488 return ret; 489 } 490 __setup("transparent_hugepage=", setup_transparent_hugepage); 491 492 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 493 { 494 if (likely(vma->vm_flags & VM_WRITE)) 495 pmd = pmd_mkwrite(pmd); 496 return pmd; 497 } 498 499 static inline struct list_head *page_deferred_list(struct page *page) 500 { 501 /* ->lru in the tail pages is occupied by compound_head. */ 502 return &page[2].deferred_list; 503 } 504 505 void prep_transhuge_page(struct page *page) 506 { 507 /* 508 * we use page->mapping and page->indexlru in second tail page 509 * as list_head: assuming THP order >= 2 510 */ 511 512 INIT_LIST_HEAD(page_deferred_list(page)); 513 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 514 } 515 516 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, 517 loff_t off, unsigned long flags, unsigned long size) 518 { 519 unsigned long addr; 520 loff_t off_end = off + len; 521 loff_t off_align = round_up(off, size); 522 unsigned long len_pad; 523 524 if (off_end <= off_align || (off_end - off_align) < size) 525 return 0; 526 527 len_pad = len + size; 528 if (len_pad < len || (off + len_pad) < off) 529 return 0; 530 531 addr = current->mm->get_unmapped_area(filp, 0, len_pad, 532 off >> PAGE_SHIFT, flags); 533 if (IS_ERR_VALUE(addr)) 534 return 0; 535 536 addr += (off - addr) & (size - 1); 537 return addr; 538 } 539 540 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 541 unsigned long len, unsigned long pgoff, unsigned long flags) 542 { 543 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 544 545 if (addr) 546 goto out; 547 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) 548 goto out; 549 550 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); 551 if (addr) 552 return addr; 553 554 out: 555 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 556 } 557 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 558 559 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 560 struct page *page, gfp_t gfp) 561 { 562 struct vm_area_struct *vma = vmf->vma; 563 struct mem_cgroup *memcg; 564 pgtable_t pgtable; 565 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 566 vm_fault_t ret = 0; 567 568 VM_BUG_ON_PAGE(!PageCompound(page), page); 569 570 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { 571 put_page(page); 572 count_vm_event(THP_FAULT_FALLBACK); 573 return VM_FAULT_FALLBACK; 574 } 575 576 pgtable = pte_alloc_one(vma->vm_mm); 577 if (unlikely(!pgtable)) { 578 ret = VM_FAULT_OOM; 579 goto release; 580 } 581 582 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 583 /* 584 * The memory barrier inside __SetPageUptodate makes sure that 585 * clear_huge_page writes become visible before the set_pmd_at() 586 * write. 587 */ 588 __SetPageUptodate(page); 589 590 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 591 if (unlikely(!pmd_none(*vmf->pmd))) { 592 goto unlock_release; 593 } else { 594 pmd_t entry; 595 596 ret = check_stable_address_space(vma->vm_mm); 597 if (ret) 598 goto unlock_release; 599 600 /* Deliver the page fault to userland */ 601 if (userfaultfd_missing(vma)) { 602 vm_fault_t ret2; 603 604 spin_unlock(vmf->ptl); 605 mem_cgroup_cancel_charge(page, memcg, true); 606 put_page(page); 607 pte_free(vma->vm_mm, pgtable); 608 ret2 = handle_userfault(vmf, VM_UFFD_MISSING); 609 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); 610 return ret2; 611 } 612 613 entry = mk_huge_pmd(page, vma->vm_page_prot); 614 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 615 page_add_new_anon_rmap(page, vma, haddr, true); 616 mem_cgroup_commit_charge(page, memcg, false, true); 617 lru_cache_add_active_or_unevictable(page, vma); 618 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 619 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 620 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 621 mm_inc_nr_ptes(vma->vm_mm); 622 spin_unlock(vmf->ptl); 623 count_vm_event(THP_FAULT_ALLOC); 624 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 625 } 626 627 return 0; 628 unlock_release: 629 spin_unlock(vmf->ptl); 630 release: 631 if (pgtable) 632 pte_free(vma->vm_mm, pgtable); 633 mem_cgroup_cancel_charge(page, memcg, true); 634 put_page(page); 635 return ret; 636 637 } 638 639 /* 640 * always: directly stall for all thp allocations 641 * defer: wake kswapd and fail if not immediately available 642 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 643 * fail if not immediately available 644 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 645 * available 646 * never: never stall for any thp allocation 647 */ 648 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr) 649 { 650 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); 651 const gfp_t gfp_mask = GFP_TRANSHUGE_LIGHT | __GFP_THISNODE; 652 653 /* Always do synchronous compaction */ 654 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 655 return GFP_TRANSHUGE | __GFP_THISNODE | 656 (vma_madvised ? 0 : __GFP_NORETRY); 657 658 /* Kick kcompactd and fail quickly */ 659 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 660 return gfp_mask | __GFP_KSWAPD_RECLAIM; 661 662 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 663 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 664 return gfp_mask | (vma_madvised ? __GFP_DIRECT_RECLAIM : 665 __GFP_KSWAPD_RECLAIM); 666 667 /* Only do synchronous compaction if madvised */ 668 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 669 return gfp_mask | (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 670 671 return gfp_mask; 672 } 673 674 /* Caller must hold page table lock. */ 675 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 676 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 677 struct page *zero_page) 678 { 679 pmd_t entry; 680 if (!pmd_none(*pmd)) 681 return false; 682 entry = mk_pmd(zero_page, vma->vm_page_prot); 683 entry = pmd_mkhuge(entry); 684 if (pgtable) 685 pgtable_trans_huge_deposit(mm, pmd, pgtable); 686 set_pmd_at(mm, haddr, pmd, entry); 687 mm_inc_nr_ptes(mm); 688 return true; 689 } 690 691 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 692 { 693 struct vm_area_struct *vma = vmf->vma; 694 gfp_t gfp; 695 struct page *page; 696 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 697 698 if (!transhuge_vma_suitable(vma, haddr)) 699 return VM_FAULT_FALLBACK; 700 if (unlikely(anon_vma_prepare(vma))) 701 return VM_FAULT_OOM; 702 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 703 return VM_FAULT_OOM; 704 if (!(vmf->flags & FAULT_FLAG_WRITE) && 705 !mm_forbids_zeropage(vma->vm_mm) && 706 transparent_hugepage_use_zero_page()) { 707 pgtable_t pgtable; 708 struct page *zero_page; 709 bool set; 710 vm_fault_t ret; 711 pgtable = pte_alloc_one(vma->vm_mm); 712 if (unlikely(!pgtable)) 713 return VM_FAULT_OOM; 714 zero_page = mm_get_huge_zero_page(vma->vm_mm); 715 if (unlikely(!zero_page)) { 716 pte_free(vma->vm_mm, pgtable); 717 count_vm_event(THP_FAULT_FALLBACK); 718 return VM_FAULT_FALLBACK; 719 } 720 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 721 ret = 0; 722 set = false; 723 if (pmd_none(*vmf->pmd)) { 724 ret = check_stable_address_space(vma->vm_mm); 725 if (ret) { 726 spin_unlock(vmf->ptl); 727 } else if (userfaultfd_missing(vma)) { 728 spin_unlock(vmf->ptl); 729 ret = handle_userfault(vmf, VM_UFFD_MISSING); 730 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 731 } else { 732 set_huge_zero_page(pgtable, vma->vm_mm, vma, 733 haddr, vmf->pmd, zero_page); 734 spin_unlock(vmf->ptl); 735 set = true; 736 } 737 } else 738 spin_unlock(vmf->ptl); 739 if (!set) 740 pte_free(vma->vm_mm, pgtable); 741 return ret; 742 } 743 gfp = alloc_hugepage_direct_gfpmask(vma, haddr); 744 page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, vma, haddr, numa_node_id()); 745 if (unlikely(!page)) { 746 count_vm_event(THP_FAULT_FALLBACK); 747 return VM_FAULT_FALLBACK; 748 } 749 prep_transhuge_page(page); 750 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 751 } 752 753 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 754 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 755 pgtable_t pgtable) 756 { 757 struct mm_struct *mm = vma->vm_mm; 758 pmd_t entry; 759 spinlock_t *ptl; 760 761 ptl = pmd_lock(mm, pmd); 762 if (!pmd_none(*pmd)) { 763 if (write) { 764 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 765 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 766 goto out_unlock; 767 } 768 entry = pmd_mkyoung(*pmd); 769 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 770 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 771 update_mmu_cache_pmd(vma, addr, pmd); 772 } 773 774 goto out_unlock; 775 } 776 777 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 778 if (pfn_t_devmap(pfn)) 779 entry = pmd_mkdevmap(entry); 780 if (write) { 781 entry = pmd_mkyoung(pmd_mkdirty(entry)); 782 entry = maybe_pmd_mkwrite(entry, vma); 783 } 784 785 if (pgtable) { 786 pgtable_trans_huge_deposit(mm, pmd, pgtable); 787 mm_inc_nr_ptes(mm); 788 pgtable = NULL; 789 } 790 791 set_pmd_at(mm, addr, pmd, entry); 792 update_mmu_cache_pmd(vma, addr, pmd); 793 794 out_unlock: 795 spin_unlock(ptl); 796 if (pgtable) 797 pte_free(mm, pgtable); 798 } 799 800 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 801 { 802 unsigned long addr = vmf->address & PMD_MASK; 803 struct vm_area_struct *vma = vmf->vma; 804 pgprot_t pgprot = vma->vm_page_prot; 805 pgtable_t pgtable = NULL; 806 807 /* 808 * If we had pmd_special, we could avoid all these restrictions, 809 * but we need to be consistent with PTEs and architectures that 810 * can't support a 'special' bit. 811 */ 812 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 813 !pfn_t_devmap(pfn)); 814 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 815 (VM_PFNMAP|VM_MIXEDMAP)); 816 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 817 818 if (addr < vma->vm_start || addr >= vma->vm_end) 819 return VM_FAULT_SIGBUS; 820 821 if (arch_needs_pgtable_deposit()) { 822 pgtable = pte_alloc_one(vma->vm_mm); 823 if (!pgtable) 824 return VM_FAULT_OOM; 825 } 826 827 track_pfn_insert(vma, &pgprot, pfn); 828 829 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 830 return VM_FAULT_NOPAGE; 831 } 832 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 833 834 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 835 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 836 { 837 if (likely(vma->vm_flags & VM_WRITE)) 838 pud = pud_mkwrite(pud); 839 return pud; 840 } 841 842 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 843 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 844 { 845 struct mm_struct *mm = vma->vm_mm; 846 pud_t entry; 847 spinlock_t *ptl; 848 849 ptl = pud_lock(mm, pud); 850 if (!pud_none(*pud)) { 851 if (write) { 852 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 853 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 854 goto out_unlock; 855 } 856 entry = pud_mkyoung(*pud); 857 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 858 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 859 update_mmu_cache_pud(vma, addr, pud); 860 } 861 goto out_unlock; 862 } 863 864 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 865 if (pfn_t_devmap(pfn)) 866 entry = pud_mkdevmap(entry); 867 if (write) { 868 entry = pud_mkyoung(pud_mkdirty(entry)); 869 entry = maybe_pud_mkwrite(entry, vma); 870 } 871 set_pud_at(mm, addr, pud, entry); 872 update_mmu_cache_pud(vma, addr, pud); 873 874 out_unlock: 875 spin_unlock(ptl); 876 } 877 878 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 879 { 880 unsigned long addr = vmf->address & PUD_MASK; 881 struct vm_area_struct *vma = vmf->vma; 882 pgprot_t pgprot = vma->vm_page_prot; 883 884 /* 885 * If we had pud_special, we could avoid all these restrictions, 886 * but we need to be consistent with PTEs and architectures that 887 * can't support a 'special' bit. 888 */ 889 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 890 !pfn_t_devmap(pfn)); 891 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 892 (VM_PFNMAP|VM_MIXEDMAP)); 893 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 894 895 if (addr < vma->vm_start || addr >= vma->vm_end) 896 return VM_FAULT_SIGBUS; 897 898 track_pfn_insert(vma, &pgprot, pfn); 899 900 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 901 return VM_FAULT_NOPAGE; 902 } 903 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 904 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 905 906 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 907 pmd_t *pmd, int flags) 908 { 909 pmd_t _pmd; 910 911 _pmd = pmd_mkyoung(*pmd); 912 if (flags & FOLL_WRITE) 913 _pmd = pmd_mkdirty(_pmd); 914 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 915 pmd, _pmd, flags & FOLL_WRITE)) 916 update_mmu_cache_pmd(vma, addr, pmd); 917 } 918 919 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 920 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 921 { 922 unsigned long pfn = pmd_pfn(*pmd); 923 struct mm_struct *mm = vma->vm_mm; 924 struct page *page; 925 926 assert_spin_locked(pmd_lockptr(mm, pmd)); 927 928 /* 929 * When we COW a devmap PMD entry, we split it into PTEs, so we should 930 * not be in this function with `flags & FOLL_COW` set. 931 */ 932 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 933 934 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 935 return NULL; 936 937 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 938 /* pass */; 939 else 940 return NULL; 941 942 if (flags & FOLL_TOUCH) 943 touch_pmd(vma, addr, pmd, flags); 944 945 /* 946 * device mapped pages can only be returned if the 947 * caller will manage the page reference count. 948 */ 949 if (!(flags & FOLL_GET)) 950 return ERR_PTR(-EEXIST); 951 952 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 953 *pgmap = get_dev_pagemap(pfn, *pgmap); 954 if (!*pgmap) 955 return ERR_PTR(-EFAULT); 956 page = pfn_to_page(pfn); 957 get_page(page); 958 959 return page; 960 } 961 962 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 963 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 964 struct vm_area_struct *vma) 965 { 966 spinlock_t *dst_ptl, *src_ptl; 967 struct page *src_page; 968 pmd_t pmd; 969 pgtable_t pgtable = NULL; 970 int ret = -ENOMEM; 971 972 /* Skip if can be re-fill on fault */ 973 if (!vma_is_anonymous(vma)) 974 return 0; 975 976 pgtable = pte_alloc_one(dst_mm); 977 if (unlikely(!pgtable)) 978 goto out; 979 980 dst_ptl = pmd_lock(dst_mm, dst_pmd); 981 src_ptl = pmd_lockptr(src_mm, src_pmd); 982 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 983 984 ret = -EAGAIN; 985 pmd = *src_pmd; 986 987 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 988 if (unlikely(is_swap_pmd(pmd))) { 989 swp_entry_t entry = pmd_to_swp_entry(pmd); 990 991 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 992 if (is_write_migration_entry(entry)) { 993 make_migration_entry_read(&entry); 994 pmd = swp_entry_to_pmd(entry); 995 if (pmd_swp_soft_dirty(*src_pmd)) 996 pmd = pmd_swp_mksoft_dirty(pmd); 997 set_pmd_at(src_mm, addr, src_pmd, pmd); 998 } 999 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1000 mm_inc_nr_ptes(dst_mm); 1001 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1002 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1003 ret = 0; 1004 goto out_unlock; 1005 } 1006 #endif 1007 1008 if (unlikely(!pmd_trans_huge(pmd))) { 1009 pte_free(dst_mm, pgtable); 1010 goto out_unlock; 1011 } 1012 /* 1013 * When page table lock is held, the huge zero pmd should not be 1014 * under splitting since we don't split the page itself, only pmd to 1015 * a page table. 1016 */ 1017 if (is_huge_zero_pmd(pmd)) { 1018 struct page *zero_page; 1019 /* 1020 * get_huge_zero_page() will never allocate a new page here, 1021 * since we already have a zero page to copy. It just takes a 1022 * reference. 1023 */ 1024 zero_page = mm_get_huge_zero_page(dst_mm); 1025 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, 1026 zero_page); 1027 ret = 0; 1028 goto out_unlock; 1029 } 1030 1031 src_page = pmd_page(pmd); 1032 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1033 get_page(src_page); 1034 page_dup_rmap(src_page, true); 1035 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1036 mm_inc_nr_ptes(dst_mm); 1037 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1038 1039 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1040 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1041 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1042 1043 ret = 0; 1044 out_unlock: 1045 spin_unlock(src_ptl); 1046 spin_unlock(dst_ptl); 1047 out: 1048 return ret; 1049 } 1050 1051 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1052 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1053 pud_t *pud, int flags) 1054 { 1055 pud_t _pud; 1056 1057 _pud = pud_mkyoung(*pud); 1058 if (flags & FOLL_WRITE) 1059 _pud = pud_mkdirty(_pud); 1060 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1061 pud, _pud, flags & FOLL_WRITE)) 1062 update_mmu_cache_pud(vma, addr, pud); 1063 } 1064 1065 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1066 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1067 { 1068 unsigned long pfn = pud_pfn(*pud); 1069 struct mm_struct *mm = vma->vm_mm; 1070 struct page *page; 1071 1072 assert_spin_locked(pud_lockptr(mm, pud)); 1073 1074 if (flags & FOLL_WRITE && !pud_write(*pud)) 1075 return NULL; 1076 1077 if (pud_present(*pud) && pud_devmap(*pud)) 1078 /* pass */; 1079 else 1080 return NULL; 1081 1082 if (flags & FOLL_TOUCH) 1083 touch_pud(vma, addr, pud, flags); 1084 1085 /* 1086 * device mapped pages can only be returned if the 1087 * caller will manage the page reference count. 1088 */ 1089 if (!(flags & FOLL_GET)) 1090 return ERR_PTR(-EEXIST); 1091 1092 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1093 *pgmap = get_dev_pagemap(pfn, *pgmap); 1094 if (!*pgmap) 1095 return ERR_PTR(-EFAULT); 1096 page = pfn_to_page(pfn); 1097 get_page(page); 1098 1099 return page; 1100 } 1101 1102 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1103 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1104 struct vm_area_struct *vma) 1105 { 1106 spinlock_t *dst_ptl, *src_ptl; 1107 pud_t pud; 1108 int ret; 1109 1110 dst_ptl = pud_lock(dst_mm, dst_pud); 1111 src_ptl = pud_lockptr(src_mm, src_pud); 1112 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1113 1114 ret = -EAGAIN; 1115 pud = *src_pud; 1116 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1117 goto out_unlock; 1118 1119 /* 1120 * When page table lock is held, the huge zero pud should not be 1121 * under splitting since we don't split the page itself, only pud to 1122 * a page table. 1123 */ 1124 if (is_huge_zero_pud(pud)) { 1125 /* No huge zero pud yet */ 1126 } 1127 1128 pudp_set_wrprotect(src_mm, addr, src_pud); 1129 pud = pud_mkold(pud_wrprotect(pud)); 1130 set_pud_at(dst_mm, addr, dst_pud, pud); 1131 1132 ret = 0; 1133 out_unlock: 1134 spin_unlock(src_ptl); 1135 spin_unlock(dst_ptl); 1136 return ret; 1137 } 1138 1139 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1140 { 1141 pud_t entry; 1142 unsigned long haddr; 1143 bool write = vmf->flags & FAULT_FLAG_WRITE; 1144 1145 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1146 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1147 goto unlock; 1148 1149 entry = pud_mkyoung(orig_pud); 1150 if (write) 1151 entry = pud_mkdirty(entry); 1152 haddr = vmf->address & HPAGE_PUD_MASK; 1153 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1154 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1155 1156 unlock: 1157 spin_unlock(vmf->ptl); 1158 } 1159 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1160 1161 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1162 { 1163 pmd_t entry; 1164 unsigned long haddr; 1165 bool write = vmf->flags & FAULT_FLAG_WRITE; 1166 1167 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1168 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1169 goto unlock; 1170 1171 entry = pmd_mkyoung(orig_pmd); 1172 if (write) 1173 entry = pmd_mkdirty(entry); 1174 haddr = vmf->address & HPAGE_PMD_MASK; 1175 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1176 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1177 1178 unlock: 1179 spin_unlock(vmf->ptl); 1180 } 1181 1182 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, 1183 pmd_t orig_pmd, struct page *page) 1184 { 1185 struct vm_area_struct *vma = vmf->vma; 1186 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1187 struct mem_cgroup *memcg; 1188 pgtable_t pgtable; 1189 pmd_t _pmd; 1190 int i; 1191 vm_fault_t ret = 0; 1192 struct page **pages; 1193 struct mmu_notifier_range range; 1194 1195 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), 1196 GFP_KERNEL); 1197 if (unlikely(!pages)) { 1198 ret |= VM_FAULT_OOM; 1199 goto out; 1200 } 1201 1202 for (i = 0; i < HPAGE_PMD_NR; i++) { 1203 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, 1204 vmf->address, page_to_nid(page)); 1205 if (unlikely(!pages[i] || 1206 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, 1207 GFP_KERNEL, &memcg, false))) { 1208 if (pages[i]) 1209 put_page(pages[i]); 1210 while (--i >= 0) { 1211 memcg = (void *)page_private(pages[i]); 1212 set_page_private(pages[i], 0); 1213 mem_cgroup_cancel_charge(pages[i], memcg, 1214 false); 1215 put_page(pages[i]); 1216 } 1217 kfree(pages); 1218 ret |= VM_FAULT_OOM; 1219 goto out; 1220 } 1221 set_page_private(pages[i], (unsigned long)memcg); 1222 } 1223 1224 for (i = 0; i < HPAGE_PMD_NR; i++) { 1225 copy_user_highpage(pages[i], page + i, 1226 haddr + PAGE_SIZE * i, vma); 1227 __SetPageUptodate(pages[i]); 1228 cond_resched(); 1229 } 1230 1231 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1232 haddr, haddr + HPAGE_PMD_SIZE); 1233 mmu_notifier_invalidate_range_start(&range); 1234 1235 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1236 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1237 goto out_free_pages; 1238 VM_BUG_ON_PAGE(!PageHead(page), page); 1239 1240 /* 1241 * Leave pmd empty until pte is filled note we must notify here as 1242 * concurrent CPU thread might write to new page before the call to 1243 * mmu_notifier_invalidate_range_end() happens which can lead to a 1244 * device seeing memory write in different order than CPU. 1245 * 1246 * See Documentation/vm/mmu_notifier.rst 1247 */ 1248 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1249 1250 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); 1251 pmd_populate(vma->vm_mm, &_pmd, pgtable); 1252 1253 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1254 pte_t entry; 1255 entry = mk_pte(pages[i], vma->vm_page_prot); 1256 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1257 memcg = (void *)page_private(pages[i]); 1258 set_page_private(pages[i], 0); 1259 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); 1260 mem_cgroup_commit_charge(pages[i], memcg, false, false); 1261 lru_cache_add_active_or_unevictable(pages[i], vma); 1262 vmf->pte = pte_offset_map(&_pmd, haddr); 1263 VM_BUG_ON(!pte_none(*vmf->pte)); 1264 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); 1265 pte_unmap(vmf->pte); 1266 } 1267 kfree(pages); 1268 1269 smp_wmb(); /* make pte visible before pmd */ 1270 pmd_populate(vma->vm_mm, vmf->pmd, pgtable); 1271 page_remove_rmap(page, true); 1272 spin_unlock(vmf->ptl); 1273 1274 /* 1275 * No need to double call mmu_notifier->invalidate_range() callback as 1276 * the above pmdp_huge_clear_flush_notify() did already call it. 1277 */ 1278 mmu_notifier_invalidate_range_only_end(&range); 1279 1280 ret |= VM_FAULT_WRITE; 1281 put_page(page); 1282 1283 out: 1284 return ret; 1285 1286 out_free_pages: 1287 spin_unlock(vmf->ptl); 1288 mmu_notifier_invalidate_range_end(&range); 1289 for (i = 0; i < HPAGE_PMD_NR; i++) { 1290 memcg = (void *)page_private(pages[i]); 1291 set_page_private(pages[i], 0); 1292 mem_cgroup_cancel_charge(pages[i], memcg, false); 1293 put_page(pages[i]); 1294 } 1295 kfree(pages); 1296 goto out; 1297 } 1298 1299 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1300 { 1301 struct vm_area_struct *vma = vmf->vma; 1302 struct page *page = NULL, *new_page; 1303 struct mem_cgroup *memcg; 1304 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1305 struct mmu_notifier_range range; 1306 gfp_t huge_gfp; /* for allocation and charge */ 1307 vm_fault_t ret = 0; 1308 1309 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1310 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1311 if (is_huge_zero_pmd(orig_pmd)) 1312 goto alloc; 1313 spin_lock(vmf->ptl); 1314 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1315 goto out_unlock; 1316 1317 page = pmd_page(orig_pmd); 1318 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1319 /* 1320 * We can only reuse the page if nobody else maps the huge page or it's 1321 * part. 1322 */ 1323 if (!trylock_page(page)) { 1324 get_page(page); 1325 spin_unlock(vmf->ptl); 1326 lock_page(page); 1327 spin_lock(vmf->ptl); 1328 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1329 unlock_page(page); 1330 put_page(page); 1331 goto out_unlock; 1332 } 1333 put_page(page); 1334 } 1335 if (reuse_swap_page(page, NULL)) { 1336 pmd_t entry; 1337 entry = pmd_mkyoung(orig_pmd); 1338 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1339 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1340 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1341 ret |= VM_FAULT_WRITE; 1342 unlock_page(page); 1343 goto out_unlock; 1344 } 1345 unlock_page(page); 1346 get_page(page); 1347 spin_unlock(vmf->ptl); 1348 alloc: 1349 if (__transparent_hugepage_enabled(vma) && 1350 !transparent_hugepage_debug_cow()) { 1351 huge_gfp = alloc_hugepage_direct_gfpmask(vma, haddr); 1352 new_page = alloc_pages_vma(huge_gfp, HPAGE_PMD_ORDER, vma, 1353 haddr, numa_node_id()); 1354 } else 1355 new_page = NULL; 1356 1357 if (likely(new_page)) { 1358 prep_transhuge_page(new_page); 1359 } else { 1360 if (!page) { 1361 split_huge_pmd(vma, vmf->pmd, vmf->address); 1362 ret |= VM_FAULT_FALLBACK; 1363 } else { 1364 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); 1365 if (ret & VM_FAULT_OOM) { 1366 split_huge_pmd(vma, vmf->pmd, vmf->address); 1367 ret |= VM_FAULT_FALLBACK; 1368 } 1369 put_page(page); 1370 } 1371 count_vm_event(THP_FAULT_FALLBACK); 1372 goto out; 1373 } 1374 1375 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, 1376 huge_gfp, &memcg, true))) { 1377 put_page(new_page); 1378 split_huge_pmd(vma, vmf->pmd, vmf->address); 1379 if (page) 1380 put_page(page); 1381 ret |= VM_FAULT_FALLBACK; 1382 count_vm_event(THP_FAULT_FALLBACK); 1383 goto out; 1384 } 1385 1386 count_vm_event(THP_FAULT_ALLOC); 1387 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 1388 1389 if (!page) 1390 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); 1391 else 1392 copy_user_huge_page(new_page, page, vmf->address, 1393 vma, HPAGE_PMD_NR); 1394 __SetPageUptodate(new_page); 1395 1396 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1397 haddr, haddr + HPAGE_PMD_SIZE); 1398 mmu_notifier_invalidate_range_start(&range); 1399 1400 spin_lock(vmf->ptl); 1401 if (page) 1402 put_page(page); 1403 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1404 spin_unlock(vmf->ptl); 1405 mem_cgroup_cancel_charge(new_page, memcg, true); 1406 put_page(new_page); 1407 goto out_mn; 1408 } else { 1409 pmd_t entry; 1410 entry = mk_huge_pmd(new_page, vma->vm_page_prot); 1411 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1412 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1413 page_add_new_anon_rmap(new_page, vma, haddr, true); 1414 mem_cgroup_commit_charge(new_page, memcg, false, true); 1415 lru_cache_add_active_or_unevictable(new_page, vma); 1416 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1417 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1418 if (!page) { 1419 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1420 } else { 1421 VM_BUG_ON_PAGE(!PageHead(page), page); 1422 page_remove_rmap(page, true); 1423 put_page(page); 1424 } 1425 ret |= VM_FAULT_WRITE; 1426 } 1427 spin_unlock(vmf->ptl); 1428 out_mn: 1429 /* 1430 * No need to double call mmu_notifier->invalidate_range() callback as 1431 * the above pmdp_huge_clear_flush_notify() did already call it. 1432 */ 1433 mmu_notifier_invalidate_range_only_end(&range); 1434 out: 1435 return ret; 1436 out_unlock: 1437 spin_unlock(vmf->ptl); 1438 return ret; 1439 } 1440 1441 /* 1442 * FOLL_FORCE can write to even unwritable pmd's, but only 1443 * after we've gone through a COW cycle and they are dirty. 1444 */ 1445 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1446 { 1447 return pmd_write(pmd) || 1448 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1449 } 1450 1451 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1452 unsigned long addr, 1453 pmd_t *pmd, 1454 unsigned int flags) 1455 { 1456 struct mm_struct *mm = vma->vm_mm; 1457 struct page *page = NULL; 1458 1459 assert_spin_locked(pmd_lockptr(mm, pmd)); 1460 1461 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1462 goto out; 1463 1464 /* Avoid dumping huge zero page */ 1465 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1466 return ERR_PTR(-EFAULT); 1467 1468 /* Full NUMA hinting faults to serialise migration in fault paths */ 1469 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1470 goto out; 1471 1472 page = pmd_page(*pmd); 1473 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1474 if (flags & FOLL_TOUCH) 1475 touch_pmd(vma, addr, pmd, flags); 1476 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1477 /* 1478 * We don't mlock() pte-mapped THPs. This way we can avoid 1479 * leaking mlocked pages into non-VM_LOCKED VMAs. 1480 * 1481 * For anon THP: 1482 * 1483 * In most cases the pmd is the only mapping of the page as we 1484 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1485 * writable private mappings in populate_vma_page_range(). 1486 * 1487 * The only scenario when we have the page shared here is if we 1488 * mlocking read-only mapping shared over fork(). We skip 1489 * mlocking such pages. 1490 * 1491 * For file THP: 1492 * 1493 * We can expect PageDoubleMap() to be stable under page lock: 1494 * for file pages we set it in page_add_file_rmap(), which 1495 * requires page to be locked. 1496 */ 1497 1498 if (PageAnon(page) && compound_mapcount(page) != 1) 1499 goto skip_mlock; 1500 if (PageDoubleMap(page) || !page->mapping) 1501 goto skip_mlock; 1502 if (!trylock_page(page)) 1503 goto skip_mlock; 1504 lru_add_drain(); 1505 if (page->mapping && !PageDoubleMap(page)) 1506 mlock_vma_page(page); 1507 unlock_page(page); 1508 } 1509 skip_mlock: 1510 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1511 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1512 if (flags & FOLL_GET) 1513 get_page(page); 1514 1515 out: 1516 return page; 1517 } 1518 1519 /* NUMA hinting page fault entry point for trans huge pmds */ 1520 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1521 { 1522 struct vm_area_struct *vma = vmf->vma; 1523 struct anon_vma *anon_vma = NULL; 1524 struct page *page; 1525 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1526 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1527 int target_nid, last_cpupid = -1; 1528 bool page_locked; 1529 bool migrated = false; 1530 bool was_writable; 1531 int flags = 0; 1532 1533 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1534 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1535 goto out_unlock; 1536 1537 /* 1538 * If there are potential migrations, wait for completion and retry 1539 * without disrupting NUMA hinting information. Do not relock and 1540 * check_same as the page may no longer be mapped. 1541 */ 1542 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1543 page = pmd_page(*vmf->pmd); 1544 if (!get_page_unless_zero(page)) 1545 goto out_unlock; 1546 spin_unlock(vmf->ptl); 1547 put_and_wait_on_page_locked(page); 1548 goto out; 1549 } 1550 1551 page = pmd_page(pmd); 1552 BUG_ON(is_huge_zero_page(page)); 1553 page_nid = page_to_nid(page); 1554 last_cpupid = page_cpupid_last(page); 1555 count_vm_numa_event(NUMA_HINT_FAULTS); 1556 if (page_nid == this_nid) { 1557 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1558 flags |= TNF_FAULT_LOCAL; 1559 } 1560 1561 /* See similar comment in do_numa_page for explanation */ 1562 if (!pmd_savedwrite(pmd)) 1563 flags |= TNF_NO_GROUP; 1564 1565 /* 1566 * Acquire the page lock to serialise THP migrations but avoid dropping 1567 * page_table_lock if at all possible 1568 */ 1569 page_locked = trylock_page(page); 1570 target_nid = mpol_misplaced(page, vma, haddr); 1571 if (target_nid == NUMA_NO_NODE) { 1572 /* If the page was locked, there are no parallel migrations */ 1573 if (page_locked) 1574 goto clear_pmdnuma; 1575 } 1576 1577 /* Migration could have started since the pmd_trans_migrating check */ 1578 if (!page_locked) { 1579 page_nid = NUMA_NO_NODE; 1580 if (!get_page_unless_zero(page)) 1581 goto out_unlock; 1582 spin_unlock(vmf->ptl); 1583 put_and_wait_on_page_locked(page); 1584 goto out; 1585 } 1586 1587 /* 1588 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1589 * to serialises splits 1590 */ 1591 get_page(page); 1592 spin_unlock(vmf->ptl); 1593 anon_vma = page_lock_anon_vma_read(page); 1594 1595 /* Confirm the PMD did not change while page_table_lock was released */ 1596 spin_lock(vmf->ptl); 1597 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1598 unlock_page(page); 1599 put_page(page); 1600 page_nid = NUMA_NO_NODE; 1601 goto out_unlock; 1602 } 1603 1604 /* Bail if we fail to protect against THP splits for any reason */ 1605 if (unlikely(!anon_vma)) { 1606 put_page(page); 1607 page_nid = NUMA_NO_NODE; 1608 goto clear_pmdnuma; 1609 } 1610 1611 /* 1612 * Since we took the NUMA fault, we must have observed the !accessible 1613 * bit. Make sure all other CPUs agree with that, to avoid them 1614 * modifying the page we're about to migrate. 1615 * 1616 * Must be done under PTL such that we'll observe the relevant 1617 * inc_tlb_flush_pending(). 1618 * 1619 * We are not sure a pending tlb flush here is for a huge page 1620 * mapping or not. Hence use the tlb range variant 1621 */ 1622 if (mm_tlb_flush_pending(vma->vm_mm)) { 1623 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1624 /* 1625 * change_huge_pmd() released the pmd lock before 1626 * invalidating the secondary MMUs sharing the primary 1627 * MMU pagetables (with ->invalidate_range()). The 1628 * mmu_notifier_invalidate_range_end() (which 1629 * internally calls ->invalidate_range()) in 1630 * change_pmd_range() will run after us, so we can't 1631 * rely on it here and we need an explicit invalidate. 1632 */ 1633 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1634 haddr + HPAGE_PMD_SIZE); 1635 } 1636 1637 /* 1638 * Migrate the THP to the requested node, returns with page unlocked 1639 * and access rights restored. 1640 */ 1641 spin_unlock(vmf->ptl); 1642 1643 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1644 vmf->pmd, pmd, vmf->address, page, target_nid); 1645 if (migrated) { 1646 flags |= TNF_MIGRATED; 1647 page_nid = target_nid; 1648 } else 1649 flags |= TNF_MIGRATE_FAIL; 1650 1651 goto out; 1652 clear_pmdnuma: 1653 BUG_ON(!PageLocked(page)); 1654 was_writable = pmd_savedwrite(pmd); 1655 pmd = pmd_modify(pmd, vma->vm_page_prot); 1656 pmd = pmd_mkyoung(pmd); 1657 if (was_writable) 1658 pmd = pmd_mkwrite(pmd); 1659 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1660 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1661 unlock_page(page); 1662 out_unlock: 1663 spin_unlock(vmf->ptl); 1664 1665 out: 1666 if (anon_vma) 1667 page_unlock_anon_vma_read(anon_vma); 1668 1669 if (page_nid != NUMA_NO_NODE) 1670 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1671 flags); 1672 1673 return 0; 1674 } 1675 1676 /* 1677 * Return true if we do MADV_FREE successfully on entire pmd page. 1678 * Otherwise, return false. 1679 */ 1680 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1681 pmd_t *pmd, unsigned long addr, unsigned long next) 1682 { 1683 spinlock_t *ptl; 1684 pmd_t orig_pmd; 1685 struct page *page; 1686 struct mm_struct *mm = tlb->mm; 1687 bool ret = false; 1688 1689 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1690 1691 ptl = pmd_trans_huge_lock(pmd, vma); 1692 if (!ptl) 1693 goto out_unlocked; 1694 1695 orig_pmd = *pmd; 1696 if (is_huge_zero_pmd(orig_pmd)) 1697 goto out; 1698 1699 if (unlikely(!pmd_present(orig_pmd))) { 1700 VM_BUG_ON(thp_migration_supported() && 1701 !is_pmd_migration_entry(orig_pmd)); 1702 goto out; 1703 } 1704 1705 page = pmd_page(orig_pmd); 1706 /* 1707 * If other processes are mapping this page, we couldn't discard 1708 * the page unless they all do MADV_FREE so let's skip the page. 1709 */ 1710 if (page_mapcount(page) != 1) 1711 goto out; 1712 1713 if (!trylock_page(page)) 1714 goto out; 1715 1716 /* 1717 * If user want to discard part-pages of THP, split it so MADV_FREE 1718 * will deactivate only them. 1719 */ 1720 if (next - addr != HPAGE_PMD_SIZE) { 1721 get_page(page); 1722 spin_unlock(ptl); 1723 split_huge_page(page); 1724 unlock_page(page); 1725 put_page(page); 1726 goto out_unlocked; 1727 } 1728 1729 if (PageDirty(page)) 1730 ClearPageDirty(page); 1731 unlock_page(page); 1732 1733 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1734 pmdp_invalidate(vma, addr, pmd); 1735 orig_pmd = pmd_mkold(orig_pmd); 1736 orig_pmd = pmd_mkclean(orig_pmd); 1737 1738 set_pmd_at(mm, addr, pmd, orig_pmd); 1739 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1740 } 1741 1742 mark_page_lazyfree(page); 1743 ret = true; 1744 out: 1745 spin_unlock(ptl); 1746 out_unlocked: 1747 return ret; 1748 } 1749 1750 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1751 { 1752 pgtable_t pgtable; 1753 1754 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1755 pte_free(mm, pgtable); 1756 mm_dec_nr_ptes(mm); 1757 } 1758 1759 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1760 pmd_t *pmd, unsigned long addr) 1761 { 1762 pmd_t orig_pmd; 1763 spinlock_t *ptl; 1764 1765 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1766 1767 ptl = __pmd_trans_huge_lock(pmd, vma); 1768 if (!ptl) 1769 return 0; 1770 /* 1771 * For architectures like ppc64 we look at deposited pgtable 1772 * when calling pmdp_huge_get_and_clear. So do the 1773 * pgtable_trans_huge_withdraw after finishing pmdp related 1774 * operations. 1775 */ 1776 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, 1777 tlb->fullmm); 1778 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1779 if (vma_is_dax(vma)) { 1780 if (arch_needs_pgtable_deposit()) 1781 zap_deposited_table(tlb->mm, pmd); 1782 spin_unlock(ptl); 1783 if (is_huge_zero_pmd(orig_pmd)) 1784 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1785 } else if (is_huge_zero_pmd(orig_pmd)) { 1786 zap_deposited_table(tlb->mm, pmd); 1787 spin_unlock(ptl); 1788 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1789 } else { 1790 struct page *page = NULL; 1791 int flush_needed = 1; 1792 1793 if (pmd_present(orig_pmd)) { 1794 page = pmd_page(orig_pmd); 1795 page_remove_rmap(page, true); 1796 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1797 VM_BUG_ON_PAGE(!PageHead(page), page); 1798 } else if (thp_migration_supported()) { 1799 swp_entry_t entry; 1800 1801 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1802 entry = pmd_to_swp_entry(orig_pmd); 1803 page = pfn_to_page(swp_offset(entry)); 1804 flush_needed = 0; 1805 } else 1806 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1807 1808 if (PageAnon(page)) { 1809 zap_deposited_table(tlb->mm, pmd); 1810 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1811 } else { 1812 if (arch_needs_pgtable_deposit()) 1813 zap_deposited_table(tlb->mm, pmd); 1814 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1815 } 1816 1817 spin_unlock(ptl); 1818 if (flush_needed) 1819 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1820 } 1821 return 1; 1822 } 1823 1824 #ifndef pmd_move_must_withdraw 1825 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1826 spinlock_t *old_pmd_ptl, 1827 struct vm_area_struct *vma) 1828 { 1829 /* 1830 * With split pmd lock we also need to move preallocated 1831 * PTE page table if new_pmd is on different PMD page table. 1832 * 1833 * We also don't deposit and withdraw tables for file pages. 1834 */ 1835 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1836 } 1837 #endif 1838 1839 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1840 { 1841 #ifdef CONFIG_MEM_SOFT_DIRTY 1842 if (unlikely(is_pmd_migration_entry(pmd))) 1843 pmd = pmd_swp_mksoft_dirty(pmd); 1844 else if (pmd_present(pmd)) 1845 pmd = pmd_mksoft_dirty(pmd); 1846 #endif 1847 return pmd; 1848 } 1849 1850 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1851 unsigned long new_addr, unsigned long old_end, 1852 pmd_t *old_pmd, pmd_t *new_pmd) 1853 { 1854 spinlock_t *old_ptl, *new_ptl; 1855 pmd_t pmd; 1856 struct mm_struct *mm = vma->vm_mm; 1857 bool force_flush = false; 1858 1859 if ((old_addr & ~HPAGE_PMD_MASK) || 1860 (new_addr & ~HPAGE_PMD_MASK) || 1861 old_end - old_addr < HPAGE_PMD_SIZE) 1862 return false; 1863 1864 /* 1865 * The destination pmd shouldn't be established, free_pgtables() 1866 * should have release it. 1867 */ 1868 if (WARN_ON(!pmd_none(*new_pmd))) { 1869 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1870 return false; 1871 } 1872 1873 /* 1874 * We don't have to worry about the ordering of src and dst 1875 * ptlocks because exclusive mmap_sem prevents deadlock. 1876 */ 1877 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1878 if (old_ptl) { 1879 new_ptl = pmd_lockptr(mm, new_pmd); 1880 if (new_ptl != old_ptl) 1881 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1882 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1883 if (pmd_present(pmd)) 1884 force_flush = true; 1885 VM_BUG_ON(!pmd_none(*new_pmd)); 1886 1887 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1888 pgtable_t pgtable; 1889 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1890 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1891 } 1892 pmd = move_soft_dirty_pmd(pmd); 1893 set_pmd_at(mm, new_addr, new_pmd, pmd); 1894 if (force_flush) 1895 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1896 if (new_ptl != old_ptl) 1897 spin_unlock(new_ptl); 1898 spin_unlock(old_ptl); 1899 return true; 1900 } 1901 return false; 1902 } 1903 1904 /* 1905 * Returns 1906 * - 0 if PMD could not be locked 1907 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1908 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1909 */ 1910 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1911 unsigned long addr, pgprot_t newprot, int prot_numa) 1912 { 1913 struct mm_struct *mm = vma->vm_mm; 1914 spinlock_t *ptl; 1915 pmd_t entry; 1916 bool preserve_write; 1917 int ret; 1918 1919 ptl = __pmd_trans_huge_lock(pmd, vma); 1920 if (!ptl) 1921 return 0; 1922 1923 preserve_write = prot_numa && pmd_write(*pmd); 1924 ret = 1; 1925 1926 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1927 if (is_swap_pmd(*pmd)) { 1928 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1929 1930 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1931 if (is_write_migration_entry(entry)) { 1932 pmd_t newpmd; 1933 /* 1934 * A protection check is difficult so 1935 * just be safe and disable write 1936 */ 1937 make_migration_entry_read(&entry); 1938 newpmd = swp_entry_to_pmd(entry); 1939 if (pmd_swp_soft_dirty(*pmd)) 1940 newpmd = pmd_swp_mksoft_dirty(newpmd); 1941 set_pmd_at(mm, addr, pmd, newpmd); 1942 } 1943 goto unlock; 1944 } 1945 #endif 1946 1947 /* 1948 * Avoid trapping faults against the zero page. The read-only 1949 * data is likely to be read-cached on the local CPU and 1950 * local/remote hits to the zero page are not interesting. 1951 */ 1952 if (prot_numa && is_huge_zero_pmd(*pmd)) 1953 goto unlock; 1954 1955 if (prot_numa && pmd_protnone(*pmd)) 1956 goto unlock; 1957 1958 /* 1959 * In case prot_numa, we are under down_read(mmap_sem). It's critical 1960 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1961 * which is also under down_read(mmap_sem): 1962 * 1963 * CPU0: CPU1: 1964 * change_huge_pmd(prot_numa=1) 1965 * pmdp_huge_get_and_clear_notify() 1966 * madvise_dontneed() 1967 * zap_pmd_range() 1968 * pmd_trans_huge(*pmd) == 0 (without ptl) 1969 * // skip the pmd 1970 * set_pmd_at(); 1971 * // pmd is re-established 1972 * 1973 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1974 * which may break userspace. 1975 * 1976 * pmdp_invalidate() is required to make sure we don't miss 1977 * dirty/young flags set by hardware. 1978 */ 1979 entry = pmdp_invalidate(vma, addr, pmd); 1980 1981 entry = pmd_modify(entry, newprot); 1982 if (preserve_write) 1983 entry = pmd_mk_savedwrite(entry); 1984 ret = HPAGE_PMD_NR; 1985 set_pmd_at(mm, addr, pmd, entry); 1986 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1987 unlock: 1988 spin_unlock(ptl); 1989 return ret; 1990 } 1991 1992 /* 1993 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1994 * 1995 * Note that if it returns page table lock pointer, this routine returns without 1996 * unlocking page table lock. So callers must unlock it. 1997 */ 1998 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1999 { 2000 spinlock_t *ptl; 2001 ptl = pmd_lock(vma->vm_mm, pmd); 2002 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2003 pmd_devmap(*pmd))) 2004 return ptl; 2005 spin_unlock(ptl); 2006 return NULL; 2007 } 2008 2009 /* 2010 * Returns true if a given pud maps a thp, false otherwise. 2011 * 2012 * Note that if it returns true, this routine returns without unlocking page 2013 * table lock. So callers must unlock it. 2014 */ 2015 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2016 { 2017 spinlock_t *ptl; 2018 2019 ptl = pud_lock(vma->vm_mm, pud); 2020 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2021 return ptl; 2022 spin_unlock(ptl); 2023 return NULL; 2024 } 2025 2026 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2027 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2028 pud_t *pud, unsigned long addr) 2029 { 2030 spinlock_t *ptl; 2031 2032 ptl = __pud_trans_huge_lock(pud, vma); 2033 if (!ptl) 2034 return 0; 2035 /* 2036 * For architectures like ppc64 we look at deposited pgtable 2037 * when calling pudp_huge_get_and_clear. So do the 2038 * pgtable_trans_huge_withdraw after finishing pudp related 2039 * operations. 2040 */ 2041 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 2042 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2043 if (vma_is_dax(vma)) { 2044 spin_unlock(ptl); 2045 /* No zero page support yet */ 2046 } else { 2047 /* No support for anonymous PUD pages yet */ 2048 BUG(); 2049 } 2050 return 1; 2051 } 2052 2053 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2054 unsigned long haddr) 2055 { 2056 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2057 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2058 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2059 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2060 2061 count_vm_event(THP_SPLIT_PUD); 2062 2063 pudp_huge_clear_flush_notify(vma, haddr, pud); 2064 } 2065 2066 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2067 unsigned long address) 2068 { 2069 spinlock_t *ptl; 2070 struct mmu_notifier_range range; 2071 2072 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2073 address & HPAGE_PUD_MASK, 2074 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2075 mmu_notifier_invalidate_range_start(&range); 2076 ptl = pud_lock(vma->vm_mm, pud); 2077 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2078 goto out; 2079 __split_huge_pud_locked(vma, pud, range.start); 2080 2081 out: 2082 spin_unlock(ptl); 2083 /* 2084 * No need to double call mmu_notifier->invalidate_range() callback as 2085 * the above pudp_huge_clear_flush_notify() did already call it. 2086 */ 2087 mmu_notifier_invalidate_range_only_end(&range); 2088 } 2089 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2090 2091 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2092 unsigned long haddr, pmd_t *pmd) 2093 { 2094 struct mm_struct *mm = vma->vm_mm; 2095 pgtable_t pgtable; 2096 pmd_t _pmd; 2097 int i; 2098 2099 /* 2100 * Leave pmd empty until pte is filled note that it is fine to delay 2101 * notification until mmu_notifier_invalidate_range_end() as we are 2102 * replacing a zero pmd write protected page with a zero pte write 2103 * protected page. 2104 * 2105 * See Documentation/vm/mmu_notifier.rst 2106 */ 2107 pmdp_huge_clear_flush(vma, haddr, pmd); 2108 2109 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2110 pmd_populate(mm, &_pmd, pgtable); 2111 2112 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2113 pte_t *pte, entry; 2114 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2115 entry = pte_mkspecial(entry); 2116 pte = pte_offset_map(&_pmd, haddr); 2117 VM_BUG_ON(!pte_none(*pte)); 2118 set_pte_at(mm, haddr, pte, entry); 2119 pte_unmap(pte); 2120 } 2121 smp_wmb(); /* make pte visible before pmd */ 2122 pmd_populate(mm, pmd, pgtable); 2123 } 2124 2125 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2126 unsigned long haddr, bool freeze) 2127 { 2128 struct mm_struct *mm = vma->vm_mm; 2129 struct page *page; 2130 pgtable_t pgtable; 2131 pmd_t old_pmd, _pmd; 2132 bool young, write, soft_dirty, pmd_migration = false; 2133 unsigned long addr; 2134 int i; 2135 2136 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2137 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2138 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2139 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2140 && !pmd_devmap(*pmd)); 2141 2142 count_vm_event(THP_SPLIT_PMD); 2143 2144 if (!vma_is_anonymous(vma)) { 2145 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2146 /* 2147 * We are going to unmap this huge page. So 2148 * just go ahead and zap it 2149 */ 2150 if (arch_needs_pgtable_deposit()) 2151 zap_deposited_table(mm, pmd); 2152 if (vma_is_dax(vma)) 2153 return; 2154 page = pmd_page(_pmd); 2155 if (!PageDirty(page) && pmd_dirty(_pmd)) 2156 set_page_dirty(page); 2157 if (!PageReferenced(page) && pmd_young(_pmd)) 2158 SetPageReferenced(page); 2159 page_remove_rmap(page, true); 2160 put_page(page); 2161 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2162 return; 2163 } else if (is_huge_zero_pmd(*pmd)) { 2164 /* 2165 * FIXME: Do we want to invalidate secondary mmu by calling 2166 * mmu_notifier_invalidate_range() see comments below inside 2167 * __split_huge_pmd() ? 2168 * 2169 * We are going from a zero huge page write protected to zero 2170 * small page also write protected so it does not seems useful 2171 * to invalidate secondary mmu at this time. 2172 */ 2173 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2174 } 2175 2176 /* 2177 * Up to this point the pmd is present and huge and userland has the 2178 * whole access to the hugepage during the split (which happens in 2179 * place). If we overwrite the pmd with the not-huge version pointing 2180 * to the pte here (which of course we could if all CPUs were bug 2181 * free), userland could trigger a small page size TLB miss on the 2182 * small sized TLB while the hugepage TLB entry is still established in 2183 * the huge TLB. Some CPU doesn't like that. 2184 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum 2185 * 383 on page 93. Intel should be safe but is also warns that it's 2186 * only safe if the permission and cache attributes of the two entries 2187 * loaded in the two TLB is identical (which should be the case here). 2188 * But it is generally safer to never allow small and huge TLB entries 2189 * for the same virtual address to be loaded simultaneously. So instead 2190 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2191 * current pmd notpresent (atomically because here the pmd_trans_huge 2192 * must remain set at all times on the pmd until the split is complete 2193 * for this pmd), then we flush the SMP TLB and finally we write the 2194 * non-huge version of the pmd entry with pmd_populate. 2195 */ 2196 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2197 2198 pmd_migration = is_pmd_migration_entry(old_pmd); 2199 if (unlikely(pmd_migration)) { 2200 swp_entry_t entry; 2201 2202 entry = pmd_to_swp_entry(old_pmd); 2203 page = pfn_to_page(swp_offset(entry)); 2204 write = is_write_migration_entry(entry); 2205 young = false; 2206 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2207 } else { 2208 page = pmd_page(old_pmd); 2209 if (pmd_dirty(old_pmd)) 2210 SetPageDirty(page); 2211 write = pmd_write(old_pmd); 2212 young = pmd_young(old_pmd); 2213 soft_dirty = pmd_soft_dirty(old_pmd); 2214 } 2215 VM_BUG_ON_PAGE(!page_count(page), page); 2216 page_ref_add(page, HPAGE_PMD_NR - 1); 2217 2218 /* 2219 * Withdraw the table only after we mark the pmd entry invalid. 2220 * This's critical for some architectures (Power). 2221 */ 2222 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2223 pmd_populate(mm, &_pmd, pgtable); 2224 2225 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2226 pte_t entry, *pte; 2227 /* 2228 * Note that NUMA hinting access restrictions are not 2229 * transferred to avoid any possibility of altering 2230 * permissions across VMAs. 2231 */ 2232 if (freeze || pmd_migration) { 2233 swp_entry_t swp_entry; 2234 swp_entry = make_migration_entry(page + i, write); 2235 entry = swp_entry_to_pte(swp_entry); 2236 if (soft_dirty) 2237 entry = pte_swp_mksoft_dirty(entry); 2238 } else { 2239 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2240 entry = maybe_mkwrite(entry, vma); 2241 if (!write) 2242 entry = pte_wrprotect(entry); 2243 if (!young) 2244 entry = pte_mkold(entry); 2245 if (soft_dirty) 2246 entry = pte_mksoft_dirty(entry); 2247 } 2248 pte = pte_offset_map(&_pmd, addr); 2249 BUG_ON(!pte_none(*pte)); 2250 set_pte_at(mm, addr, pte, entry); 2251 atomic_inc(&page[i]._mapcount); 2252 pte_unmap(pte); 2253 } 2254 2255 /* 2256 * Set PG_double_map before dropping compound_mapcount to avoid 2257 * false-negative page_mapped(). 2258 */ 2259 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { 2260 for (i = 0; i < HPAGE_PMD_NR; i++) 2261 atomic_inc(&page[i]._mapcount); 2262 } 2263 2264 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2265 /* Last compound_mapcount is gone. */ 2266 __dec_node_page_state(page, NR_ANON_THPS); 2267 if (TestClearPageDoubleMap(page)) { 2268 /* No need in mapcount reference anymore */ 2269 for (i = 0; i < HPAGE_PMD_NR; i++) 2270 atomic_dec(&page[i]._mapcount); 2271 } 2272 } 2273 2274 smp_wmb(); /* make pte visible before pmd */ 2275 pmd_populate(mm, pmd, pgtable); 2276 2277 if (freeze) { 2278 for (i = 0; i < HPAGE_PMD_NR; i++) { 2279 page_remove_rmap(page + i, false); 2280 put_page(page + i); 2281 } 2282 } 2283 } 2284 2285 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2286 unsigned long address, bool freeze, struct page *page) 2287 { 2288 spinlock_t *ptl; 2289 struct mmu_notifier_range range; 2290 2291 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2292 address & HPAGE_PMD_MASK, 2293 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2294 mmu_notifier_invalidate_range_start(&range); 2295 ptl = pmd_lock(vma->vm_mm, pmd); 2296 2297 /* 2298 * If caller asks to setup a migration entries, we need a page to check 2299 * pmd against. Otherwise we can end up replacing wrong page. 2300 */ 2301 VM_BUG_ON(freeze && !page); 2302 if (page && page != pmd_page(*pmd)) 2303 goto out; 2304 2305 if (pmd_trans_huge(*pmd)) { 2306 page = pmd_page(*pmd); 2307 if (PageMlocked(page)) 2308 clear_page_mlock(page); 2309 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2310 goto out; 2311 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2312 out: 2313 spin_unlock(ptl); 2314 /* 2315 * No need to double call mmu_notifier->invalidate_range() callback. 2316 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2317 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2318 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2319 * fault will trigger a flush_notify before pointing to a new page 2320 * (it is fine if the secondary mmu keeps pointing to the old zero 2321 * page in the meantime) 2322 * 3) Split a huge pmd into pte pointing to the same page. No need 2323 * to invalidate secondary tlb entry they are all still valid. 2324 * any further changes to individual pte will notify. So no need 2325 * to call mmu_notifier->invalidate_range() 2326 */ 2327 mmu_notifier_invalidate_range_only_end(&range); 2328 } 2329 2330 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2331 bool freeze, struct page *page) 2332 { 2333 pgd_t *pgd; 2334 p4d_t *p4d; 2335 pud_t *pud; 2336 pmd_t *pmd; 2337 2338 pgd = pgd_offset(vma->vm_mm, address); 2339 if (!pgd_present(*pgd)) 2340 return; 2341 2342 p4d = p4d_offset(pgd, address); 2343 if (!p4d_present(*p4d)) 2344 return; 2345 2346 pud = pud_offset(p4d, address); 2347 if (!pud_present(*pud)) 2348 return; 2349 2350 pmd = pmd_offset(pud, address); 2351 2352 __split_huge_pmd(vma, pmd, address, freeze, page); 2353 } 2354 2355 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2356 unsigned long start, 2357 unsigned long end, 2358 long adjust_next) 2359 { 2360 /* 2361 * If the new start address isn't hpage aligned and it could 2362 * previously contain an hugepage: check if we need to split 2363 * an huge pmd. 2364 */ 2365 if (start & ~HPAGE_PMD_MASK && 2366 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2367 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2368 split_huge_pmd_address(vma, start, false, NULL); 2369 2370 /* 2371 * If the new end address isn't hpage aligned and it could 2372 * previously contain an hugepage: check if we need to split 2373 * an huge pmd. 2374 */ 2375 if (end & ~HPAGE_PMD_MASK && 2376 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2377 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2378 split_huge_pmd_address(vma, end, false, NULL); 2379 2380 /* 2381 * If we're also updating the vma->vm_next->vm_start, if the new 2382 * vm_next->vm_start isn't page aligned and it could previously 2383 * contain an hugepage: check if we need to split an huge pmd. 2384 */ 2385 if (adjust_next > 0) { 2386 struct vm_area_struct *next = vma->vm_next; 2387 unsigned long nstart = next->vm_start; 2388 nstart += adjust_next << PAGE_SHIFT; 2389 if (nstart & ~HPAGE_PMD_MASK && 2390 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2391 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2392 split_huge_pmd_address(next, nstart, false, NULL); 2393 } 2394 } 2395 2396 static void unmap_page(struct page *page) 2397 { 2398 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | 2399 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2400 bool unmap_success; 2401 2402 VM_BUG_ON_PAGE(!PageHead(page), page); 2403 2404 if (PageAnon(page)) 2405 ttu_flags |= TTU_SPLIT_FREEZE; 2406 2407 unmap_success = try_to_unmap(page, ttu_flags); 2408 VM_BUG_ON_PAGE(!unmap_success, page); 2409 } 2410 2411 static void remap_page(struct page *page) 2412 { 2413 int i; 2414 if (PageTransHuge(page)) { 2415 remove_migration_ptes(page, page, true); 2416 } else { 2417 for (i = 0; i < HPAGE_PMD_NR; i++) 2418 remove_migration_ptes(page + i, page + i, true); 2419 } 2420 } 2421 2422 static void __split_huge_page_tail(struct page *head, int tail, 2423 struct lruvec *lruvec, struct list_head *list) 2424 { 2425 struct page *page_tail = head + tail; 2426 2427 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2428 2429 /* 2430 * Clone page flags before unfreezing refcount. 2431 * 2432 * After successful get_page_unless_zero() might follow flags change, 2433 * for exmaple lock_page() which set PG_waiters. 2434 */ 2435 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2436 page_tail->flags |= (head->flags & 2437 ((1L << PG_referenced) | 2438 (1L << PG_swapbacked) | 2439 (1L << PG_swapcache) | 2440 (1L << PG_mlocked) | 2441 (1L << PG_uptodate) | 2442 (1L << PG_active) | 2443 (1L << PG_workingset) | 2444 (1L << PG_locked) | 2445 (1L << PG_unevictable) | 2446 (1L << PG_dirty))); 2447 2448 /* ->mapping in first tail page is compound_mapcount */ 2449 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2450 page_tail); 2451 page_tail->mapping = head->mapping; 2452 page_tail->index = head->index + tail; 2453 2454 /* Page flags must be visible before we make the page non-compound. */ 2455 smp_wmb(); 2456 2457 /* 2458 * Clear PageTail before unfreezing page refcount. 2459 * 2460 * After successful get_page_unless_zero() might follow put_page() 2461 * which needs correct compound_head(). 2462 */ 2463 clear_compound_head(page_tail); 2464 2465 /* Finally unfreeze refcount. Additional reference from page cache. */ 2466 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2467 PageSwapCache(head))); 2468 2469 if (page_is_young(head)) 2470 set_page_young(page_tail); 2471 if (page_is_idle(head)) 2472 set_page_idle(page_tail); 2473 2474 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2475 2476 /* 2477 * always add to the tail because some iterators expect new 2478 * pages to show after the currently processed elements - e.g. 2479 * migrate_pages 2480 */ 2481 lru_add_page_tail(head, page_tail, lruvec, list); 2482 } 2483 2484 static void __split_huge_page(struct page *page, struct list_head *list, 2485 pgoff_t end, unsigned long flags) 2486 { 2487 struct page *head = compound_head(page); 2488 pg_data_t *pgdat = page_pgdat(head); 2489 struct lruvec *lruvec; 2490 int i; 2491 2492 lruvec = mem_cgroup_page_lruvec(head, pgdat); 2493 2494 /* complete memcg works before add pages to LRU */ 2495 mem_cgroup_split_huge_fixup(head); 2496 2497 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { 2498 __split_huge_page_tail(head, i, lruvec, list); 2499 /* Some pages can be beyond i_size: drop them from page cache */ 2500 if (head[i].index >= end) { 2501 ClearPageDirty(head + i); 2502 __delete_from_page_cache(head + i, NULL); 2503 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2504 shmem_uncharge(head->mapping->host, 1); 2505 put_page(head + i); 2506 } 2507 } 2508 2509 ClearPageCompound(head); 2510 2511 split_page_owner(head, HPAGE_PMD_ORDER); 2512 2513 /* See comment in __split_huge_page_tail() */ 2514 if (PageAnon(head)) { 2515 /* Additional pin to swap cache */ 2516 if (PageSwapCache(head)) 2517 page_ref_add(head, 2); 2518 else 2519 page_ref_inc(head); 2520 } else { 2521 /* Additional pin to page cache */ 2522 page_ref_add(head, 2); 2523 xa_unlock(&head->mapping->i_pages); 2524 } 2525 2526 spin_unlock_irqrestore(&pgdat->lru_lock, flags); 2527 2528 remap_page(head); 2529 2530 for (i = 0; i < HPAGE_PMD_NR; i++) { 2531 struct page *subpage = head + i; 2532 if (subpage == page) 2533 continue; 2534 unlock_page(subpage); 2535 2536 /* 2537 * Subpages may be freed if there wasn't any mapping 2538 * like if add_to_swap() is running on a lru page that 2539 * had its mapping zapped. And freeing these pages 2540 * requires taking the lru_lock so we do the put_page 2541 * of the tail pages after the split is complete. 2542 */ 2543 put_page(subpage); 2544 } 2545 } 2546 2547 int total_mapcount(struct page *page) 2548 { 2549 int i, compound, ret; 2550 2551 VM_BUG_ON_PAGE(PageTail(page), page); 2552 2553 if (likely(!PageCompound(page))) 2554 return atomic_read(&page->_mapcount) + 1; 2555 2556 compound = compound_mapcount(page); 2557 if (PageHuge(page)) 2558 return compound; 2559 ret = compound; 2560 for (i = 0; i < HPAGE_PMD_NR; i++) 2561 ret += atomic_read(&page[i]._mapcount) + 1; 2562 /* File pages has compound_mapcount included in _mapcount */ 2563 if (!PageAnon(page)) 2564 return ret - compound * HPAGE_PMD_NR; 2565 if (PageDoubleMap(page)) 2566 ret -= HPAGE_PMD_NR; 2567 return ret; 2568 } 2569 2570 /* 2571 * This calculates accurately how many mappings a transparent hugepage 2572 * has (unlike page_mapcount() which isn't fully accurate). This full 2573 * accuracy is primarily needed to know if copy-on-write faults can 2574 * reuse the page and change the mapping to read-write instead of 2575 * copying them. At the same time this returns the total_mapcount too. 2576 * 2577 * The function returns the highest mapcount any one of the subpages 2578 * has. If the return value is one, even if different processes are 2579 * mapping different subpages of the transparent hugepage, they can 2580 * all reuse it, because each process is reusing a different subpage. 2581 * 2582 * The total_mapcount is instead counting all virtual mappings of the 2583 * subpages. If the total_mapcount is equal to "one", it tells the 2584 * caller all mappings belong to the same "mm" and in turn the 2585 * anon_vma of the transparent hugepage can become the vma->anon_vma 2586 * local one as no other process may be mapping any of the subpages. 2587 * 2588 * It would be more accurate to replace page_mapcount() with 2589 * page_trans_huge_mapcount(), however we only use 2590 * page_trans_huge_mapcount() in the copy-on-write faults where we 2591 * need full accuracy to avoid breaking page pinning, because 2592 * page_trans_huge_mapcount() is slower than page_mapcount(). 2593 */ 2594 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2595 { 2596 int i, ret, _total_mapcount, mapcount; 2597 2598 /* hugetlbfs shouldn't call it */ 2599 VM_BUG_ON_PAGE(PageHuge(page), page); 2600 2601 if (likely(!PageTransCompound(page))) { 2602 mapcount = atomic_read(&page->_mapcount) + 1; 2603 if (total_mapcount) 2604 *total_mapcount = mapcount; 2605 return mapcount; 2606 } 2607 2608 page = compound_head(page); 2609 2610 _total_mapcount = ret = 0; 2611 for (i = 0; i < HPAGE_PMD_NR; i++) { 2612 mapcount = atomic_read(&page[i]._mapcount) + 1; 2613 ret = max(ret, mapcount); 2614 _total_mapcount += mapcount; 2615 } 2616 if (PageDoubleMap(page)) { 2617 ret -= 1; 2618 _total_mapcount -= HPAGE_PMD_NR; 2619 } 2620 mapcount = compound_mapcount(page); 2621 ret += mapcount; 2622 _total_mapcount += mapcount; 2623 if (total_mapcount) 2624 *total_mapcount = _total_mapcount; 2625 return ret; 2626 } 2627 2628 /* Racy check whether the huge page can be split */ 2629 bool can_split_huge_page(struct page *page, int *pextra_pins) 2630 { 2631 int extra_pins; 2632 2633 /* Additional pins from page cache */ 2634 if (PageAnon(page)) 2635 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; 2636 else 2637 extra_pins = HPAGE_PMD_NR; 2638 if (pextra_pins) 2639 *pextra_pins = extra_pins; 2640 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2641 } 2642 2643 /* 2644 * This function splits huge page into normal pages. @page can point to any 2645 * subpage of huge page to split. Split doesn't change the position of @page. 2646 * 2647 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2648 * The huge page must be locked. 2649 * 2650 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2651 * 2652 * Both head page and tail pages will inherit mapping, flags, and so on from 2653 * the hugepage. 2654 * 2655 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2656 * they are not mapped. 2657 * 2658 * Returns 0 if the hugepage is split successfully. 2659 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2660 * us. 2661 */ 2662 int split_huge_page_to_list(struct page *page, struct list_head *list) 2663 { 2664 struct page *head = compound_head(page); 2665 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); 2666 struct anon_vma *anon_vma = NULL; 2667 struct address_space *mapping = NULL; 2668 int count, mapcount, extra_pins, ret; 2669 bool mlocked; 2670 unsigned long flags; 2671 pgoff_t end; 2672 2673 VM_BUG_ON_PAGE(is_huge_zero_page(page), page); 2674 VM_BUG_ON_PAGE(!PageLocked(page), page); 2675 VM_BUG_ON_PAGE(!PageCompound(page), page); 2676 2677 if (PageWriteback(page)) 2678 return -EBUSY; 2679 2680 if (PageAnon(head)) { 2681 /* 2682 * The caller does not necessarily hold an mmap_sem that would 2683 * prevent the anon_vma disappearing so we first we take a 2684 * reference to it and then lock the anon_vma for write. This 2685 * is similar to page_lock_anon_vma_read except the write lock 2686 * is taken to serialise against parallel split or collapse 2687 * operations. 2688 */ 2689 anon_vma = page_get_anon_vma(head); 2690 if (!anon_vma) { 2691 ret = -EBUSY; 2692 goto out; 2693 } 2694 end = -1; 2695 mapping = NULL; 2696 anon_vma_lock_write(anon_vma); 2697 } else { 2698 mapping = head->mapping; 2699 2700 /* Truncated ? */ 2701 if (!mapping) { 2702 ret = -EBUSY; 2703 goto out; 2704 } 2705 2706 anon_vma = NULL; 2707 i_mmap_lock_read(mapping); 2708 2709 /* 2710 *__split_huge_page() may need to trim off pages beyond EOF: 2711 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2712 * which cannot be nested inside the page tree lock. So note 2713 * end now: i_size itself may be changed at any moment, but 2714 * head page lock is good enough to serialize the trimming. 2715 */ 2716 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2717 } 2718 2719 /* 2720 * Racy check if we can split the page, before unmap_page() will 2721 * split PMDs 2722 */ 2723 if (!can_split_huge_page(head, &extra_pins)) { 2724 ret = -EBUSY; 2725 goto out_unlock; 2726 } 2727 2728 mlocked = PageMlocked(page); 2729 unmap_page(head); 2730 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2731 2732 /* Make sure the page is not on per-CPU pagevec as it takes pin */ 2733 if (mlocked) 2734 lru_add_drain(); 2735 2736 /* prevent PageLRU to go away from under us, and freeze lru stats */ 2737 spin_lock_irqsave(&pgdata->lru_lock, flags); 2738 2739 if (mapping) { 2740 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2741 2742 /* 2743 * Check if the head page is present in page cache. 2744 * We assume all tail are present too, if head is there. 2745 */ 2746 xa_lock(&mapping->i_pages); 2747 if (xas_load(&xas) != head) 2748 goto fail; 2749 } 2750 2751 /* Prevent deferred_split_scan() touching ->_refcount */ 2752 spin_lock(&pgdata->split_queue_lock); 2753 count = page_count(head); 2754 mapcount = total_mapcount(head); 2755 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2756 if (!list_empty(page_deferred_list(head))) { 2757 pgdata->split_queue_len--; 2758 list_del(page_deferred_list(head)); 2759 } 2760 if (mapping) 2761 __dec_node_page_state(page, NR_SHMEM_THPS); 2762 spin_unlock(&pgdata->split_queue_lock); 2763 __split_huge_page(page, list, end, flags); 2764 if (PageSwapCache(head)) { 2765 swp_entry_t entry = { .val = page_private(head) }; 2766 2767 ret = split_swap_cluster(entry); 2768 } else 2769 ret = 0; 2770 } else { 2771 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2772 pr_alert("total_mapcount: %u, page_count(): %u\n", 2773 mapcount, count); 2774 if (PageTail(page)) 2775 dump_page(head, NULL); 2776 dump_page(page, "total_mapcount(head) > 0"); 2777 BUG(); 2778 } 2779 spin_unlock(&pgdata->split_queue_lock); 2780 fail: if (mapping) 2781 xa_unlock(&mapping->i_pages); 2782 spin_unlock_irqrestore(&pgdata->lru_lock, flags); 2783 remap_page(head); 2784 ret = -EBUSY; 2785 } 2786 2787 out_unlock: 2788 if (anon_vma) { 2789 anon_vma_unlock_write(anon_vma); 2790 put_anon_vma(anon_vma); 2791 } 2792 if (mapping) 2793 i_mmap_unlock_read(mapping); 2794 out: 2795 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2796 return ret; 2797 } 2798 2799 void free_transhuge_page(struct page *page) 2800 { 2801 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2802 unsigned long flags; 2803 2804 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2805 if (!list_empty(page_deferred_list(page))) { 2806 pgdata->split_queue_len--; 2807 list_del(page_deferred_list(page)); 2808 } 2809 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2810 free_compound_page(page); 2811 } 2812 2813 void deferred_split_huge_page(struct page *page) 2814 { 2815 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2816 unsigned long flags; 2817 2818 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2819 2820 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2821 if (list_empty(page_deferred_list(page))) { 2822 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2823 list_add_tail(page_deferred_list(page), &pgdata->split_queue); 2824 pgdata->split_queue_len++; 2825 } 2826 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2827 } 2828 2829 static unsigned long deferred_split_count(struct shrinker *shrink, 2830 struct shrink_control *sc) 2831 { 2832 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2833 return READ_ONCE(pgdata->split_queue_len); 2834 } 2835 2836 static unsigned long deferred_split_scan(struct shrinker *shrink, 2837 struct shrink_control *sc) 2838 { 2839 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2840 unsigned long flags; 2841 LIST_HEAD(list), *pos, *next; 2842 struct page *page; 2843 int split = 0; 2844 2845 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2846 /* Take pin on all head pages to avoid freeing them under us */ 2847 list_for_each_safe(pos, next, &pgdata->split_queue) { 2848 page = list_entry((void *)pos, struct page, mapping); 2849 page = compound_head(page); 2850 if (get_page_unless_zero(page)) { 2851 list_move(page_deferred_list(page), &list); 2852 } else { 2853 /* We lost race with put_compound_page() */ 2854 list_del_init(page_deferred_list(page)); 2855 pgdata->split_queue_len--; 2856 } 2857 if (!--sc->nr_to_scan) 2858 break; 2859 } 2860 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2861 2862 list_for_each_safe(pos, next, &list) { 2863 page = list_entry((void *)pos, struct page, mapping); 2864 if (!trylock_page(page)) 2865 goto next; 2866 /* split_huge_page() removes page from list on success */ 2867 if (!split_huge_page(page)) 2868 split++; 2869 unlock_page(page); 2870 next: 2871 put_page(page); 2872 } 2873 2874 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2875 list_splice_tail(&list, &pgdata->split_queue); 2876 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2877 2878 /* 2879 * Stop shrinker if we didn't split any page, but the queue is empty. 2880 * This can happen if pages were freed under us. 2881 */ 2882 if (!split && list_empty(&pgdata->split_queue)) 2883 return SHRINK_STOP; 2884 return split; 2885 } 2886 2887 static struct shrinker deferred_split_shrinker = { 2888 .count_objects = deferred_split_count, 2889 .scan_objects = deferred_split_scan, 2890 .seeks = DEFAULT_SEEKS, 2891 .flags = SHRINKER_NUMA_AWARE, 2892 }; 2893 2894 #ifdef CONFIG_DEBUG_FS 2895 static int split_huge_pages_set(void *data, u64 val) 2896 { 2897 struct zone *zone; 2898 struct page *page; 2899 unsigned long pfn, max_zone_pfn; 2900 unsigned long total = 0, split = 0; 2901 2902 if (val != 1) 2903 return -EINVAL; 2904 2905 for_each_populated_zone(zone) { 2906 max_zone_pfn = zone_end_pfn(zone); 2907 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2908 if (!pfn_valid(pfn)) 2909 continue; 2910 2911 page = pfn_to_page(pfn); 2912 if (!get_page_unless_zero(page)) 2913 continue; 2914 2915 if (zone != page_zone(page)) 2916 goto next; 2917 2918 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2919 goto next; 2920 2921 total++; 2922 lock_page(page); 2923 if (!split_huge_page(page)) 2924 split++; 2925 unlock_page(page); 2926 next: 2927 put_page(page); 2928 } 2929 } 2930 2931 pr_info("%lu of %lu THP split\n", split, total); 2932 2933 return 0; 2934 } 2935 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 2936 "%llu\n"); 2937 2938 static int __init split_huge_pages_debugfs(void) 2939 { 2940 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 2941 &split_huge_pages_fops); 2942 return 0; 2943 } 2944 late_initcall(split_huge_pages_debugfs); 2945 #endif 2946 2947 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2948 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 2949 struct page *page) 2950 { 2951 struct vm_area_struct *vma = pvmw->vma; 2952 struct mm_struct *mm = vma->vm_mm; 2953 unsigned long address = pvmw->address; 2954 pmd_t pmdval; 2955 swp_entry_t entry; 2956 pmd_t pmdswp; 2957 2958 if (!(pvmw->pmd && !pvmw->pte)) 2959 return; 2960 2961 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 2962 pmdval = *pvmw->pmd; 2963 pmdp_invalidate(vma, address, pvmw->pmd); 2964 if (pmd_dirty(pmdval)) 2965 set_page_dirty(page); 2966 entry = make_migration_entry(page, pmd_write(pmdval)); 2967 pmdswp = swp_entry_to_pmd(entry); 2968 if (pmd_soft_dirty(pmdval)) 2969 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 2970 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 2971 page_remove_rmap(page, true); 2972 put_page(page); 2973 } 2974 2975 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 2976 { 2977 struct vm_area_struct *vma = pvmw->vma; 2978 struct mm_struct *mm = vma->vm_mm; 2979 unsigned long address = pvmw->address; 2980 unsigned long mmun_start = address & HPAGE_PMD_MASK; 2981 pmd_t pmde; 2982 swp_entry_t entry; 2983 2984 if (!(pvmw->pmd && !pvmw->pte)) 2985 return; 2986 2987 entry = pmd_to_swp_entry(*pvmw->pmd); 2988 get_page(new); 2989 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 2990 if (pmd_swp_soft_dirty(*pvmw->pmd)) 2991 pmde = pmd_mksoft_dirty(pmde); 2992 if (is_write_migration_entry(entry)) 2993 pmde = maybe_pmd_mkwrite(pmde, vma); 2994 2995 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 2996 if (PageAnon(new)) 2997 page_add_anon_rmap(new, vma, mmun_start, true); 2998 else 2999 page_add_file_rmap(new, true); 3000 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3001 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 3002 mlock_vma_page(new); 3003 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3004 } 3005 #endif 3006