mm/huge_memory.c

   1 /*
   2  *  Copyright (C) 2009  Red Hat, Inc.
   3  *
   4  *  This work is licensed under the terms of the GNU GPL, version 2. See
   5  *  the COPYING file in the top-level directory.
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/mm.h>
  11 #include <linux/sched.h>
  12 #include <linux/sched/coredump.h>
  13 #include <linux/sched/numa_balancing.h>
  14 #include <linux/highmem.h>
  15 #include <linux/hugetlb.h>
  16 #include <linux/mmu_notifier.h>
  17 #include <linux/rmap.h>
  18 #include <linux/swap.h>
  19 #include <linux/shrinker.h>
  20 #include <linux/mm_inline.h>
  21 #include <linux/swapops.h>
  22 #include <linux/dax.h>
  23 #include <linux/khugepaged.h>
  24 #include <linux/freezer.h>
  25 #include <linux/pfn_t.h>
  26 #include <linux/mman.h>
  27 #include <linux/memremap.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/debugfs.h>
  30 #include <linux/migrate.h>
  31 #include <linux/hashtable.h>
  32 #include <linux/userfaultfd_k.h>
  33 #include <linux/page_idle.h>
  34 #include <linux/shmem_fs.h>
  35 #include <linux/oom.h>
  36
  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 static struct page *get_huge_zero_page(void)
  66 {
  67         struct page *zero_page;
  68 retry:
  69         if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
  70                 return READ_ONCE(huge_zero_page);
  71
  72         zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
  73                         HPAGE_PMD_ORDER);
  74         if (!zero_page) {
  75                 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
  76                 return NULL;
  77         }
  78         count_vm_event(THP_ZERO_PAGE_ALLOC);
  79         preempt_disable();
  80         if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
  81                 preempt_enable();
  82                 __free_pages(zero_page, compound_order(zero_page));
  83                 goto retry;
  84         }
  85
  86         /* We take additional reference here. It will be put back by shrinker */
  87         atomic_set(&huge_zero_refcount, 2);
  88         preempt_enable();
  89         return READ_ONCE(huge_zero_page);
  90 }
  91
  92 static void put_huge_zero_page(void)
  93 {
  94         /*
  95          * Counter should never go to zero here. Only shrinker can put
  96          * last reference.
  97          */
  98         BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
  99 }
 100
 101 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
 102 {
 103         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 104                 return READ_ONCE(huge_zero_page);
 105
 106         if (!get_huge_zero_page())
 107                 return NULL;
 108
 109         if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 110                 put_huge_zero_page();
 111
 112         return READ_ONCE(huge_zero_page);
 113 }
 114
 115 void mm_put_huge_zero_page(struct mm_struct *mm)
 116 {
 117         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 118                 put_huge_zero_page();
 119 }
 120
 121 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
 122                                         struct shrink_control *sc)
 123 {
 124         /* we can free zero page only if last reference remains */
 125         return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
 126 }
 127
 128 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
 129                                        struct shrink_control *sc)
 130 {
 131         if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
 132                 struct page *zero_page = xchg(&huge_zero_page, NULL);
 133                 BUG_ON(zero_page == NULL);
 134                 __free_pages(zero_page, compound_order(zero_page));
 135                 return HPAGE_PMD_NR;
 136         }
 137
 138         return 0;
 139 }
 140
 141 static struct shrinker huge_zero_page_shrinker = {
 142         .count_objects = shrink_huge_zero_page_count,
 143         .scan_objects = shrink_huge_zero_page_scan,
 144         .seeks = DEFAULT_SEEKS,
 145 };
 146
 147 #ifdef CONFIG_SYSFS
 148 static ssize_t enabled_show(struct kobject *kobj,
 149                             struct kobj_attribute *attr, char *buf)
 150 {
 151         if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
 152                 return sprintf(buf, "[always] madvise never\n");
 153         else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
 154                 return sprintf(buf, "always [madvise] never\n");
 155         else
 156                 return sprintf(buf, "always madvise [never]\n");
 157 }
 158
 159 static ssize_t enabled_store(struct kobject *kobj,
 160                              struct kobj_attribute *attr,
 161                              const char *buf, size_t count)
 162 {
 163         ssize_t ret = count;
 164
 165         if (!memcmp("always", buf,
 166                     min(sizeof("always")-1, count))) {
 167                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 168                 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 169         } else if (!memcmp("madvise", buf,
 170                            min(sizeof("madvise")-1, count))) {
 171                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 172                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 173         } else if (!memcmp("never", buf,
 174                            min(sizeof("never")-1, count))) {
 175                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 176                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 177         } else
 178                 ret = -EINVAL;
 179
 180         if (ret > 0) {
 181                 int err = start_stop_khugepaged();
 182                 if (err)
 183                         ret = err;
 184         }
 185         return ret;
 186 }
 187 static struct kobj_attribute enabled_attr =
 188         __ATTR(enabled, 0644, enabled_show, enabled_store);
 189
 190 ssize_t single_hugepage_flag_show(struct kobject *kobj,
 191                                 struct kobj_attribute *attr, char *buf,
 192                                 enum transparent_hugepage_flag flag)
 193 {
 194         return sprintf(buf, "%d\n",
 195                        !!test_bit(flag, &transparent_hugepage_flags));
 196 }
 197
 198 ssize_t single_hugepage_flag_store(struct kobject *kobj,
 199                                  struct kobj_attribute *attr,
 200                                  const char *buf, size_t count,
 201                                  enum transparent_hugepage_flag flag)
 202 {
 203         unsigned long value;
 204         int ret;
 205
 206         ret = kstrtoul(buf, 10, &value);
 207         if (ret < 0)
 208                 return ret;
 209         if (value > 1)
 210                 return -EINVAL;
 211
 212         if (value)
 213                 set_bit(flag, &transparent_hugepage_flags);
 214         else
 215                 clear_bit(flag, &transparent_hugepage_flags);
 216
 217         return count;
 218 }
 219
 220 static ssize_t defrag_show(struct kobject *kobj,
 221                            struct kobj_attribute *attr, char *buf)
 222 {
 223         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 224                 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
 225         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 226                 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
 227         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 228                 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
 229         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 230                 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
 231         return sprintf(buf, "always defer defer+madvise madvise [never]\n");
 232 }
 233
 234 static ssize_t defrag_store(struct kobject *kobj,
 235                             struct kobj_attribute *attr,
 236                             const char *buf, size_t count)
 237 {
 238         if (!memcmp("always", buf,
 239                     min(sizeof("always")-1, count))) {
 240                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 241                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 242                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 243                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 244         } else if (!memcmp("defer+madvise", buf,
 245                     min(sizeof("defer+madvise")-1, count))) {
 246                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 247                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 248                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 249                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 250         } else if (!memcmp("defer", buf,
 251                     min(sizeof("defer")-1, count))) {
 252                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 253                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 254                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 255                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 256         } else if (!memcmp("madvise", buf,
 257                            min(sizeof("madvise")-1, count))) {
 258                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 259                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 260                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 261                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 262         } else if (!memcmp("never", buf,
 263                            min(sizeof("never")-1, count))) {
 264                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 265                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 266                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 267                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 268         } else
 269                 return -EINVAL;
 270
 271         return count;
 272 }
 273 static struct kobj_attribute defrag_attr =
 274         __ATTR(defrag, 0644, defrag_show, defrag_store);
 275
 276 static ssize_t use_zero_page_show(struct kobject *kobj,
 277                 struct kobj_attribute *attr, char *buf)
 278 {
 279         return single_hugepage_flag_show(kobj, attr, buf,
 280                                 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 281 }
 282 static ssize_t use_zero_page_store(struct kobject *kobj,
 283                 struct kobj_attribute *attr, const char *buf, size_t count)
 284 {
 285         return single_hugepage_flag_store(kobj, attr, buf, count,
 286                                  TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 287 }
 288 static struct kobj_attribute use_zero_page_attr =
 289         __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
 290
 291 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
 292                 struct kobj_attribute *attr, char *buf)
 293 {
 294         return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
 295 }
 296 static struct kobj_attribute hpage_pmd_size_attr =
 297         __ATTR_RO(hpage_pmd_size);
 298
 299 #ifdef CONFIG_DEBUG_VM
 300 static ssize_t debug_cow_show(struct kobject *kobj,
 301                                 struct kobj_attribute *attr, char *buf)
 302 {
 303         return single_hugepage_flag_show(kobj, attr, buf,
 304                                 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
 305 }
 306 static ssize_t debug_cow_store(struct kobject *kobj,
 307                                struct kobj_attribute *attr,
 308                                const char *buf, size_t count)
 309 {
 310         return single_hugepage_flag_store(kobj, attr, buf, count,
 311                                  TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
 312 }
 313 static struct kobj_attribute debug_cow_attr =
 314         __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
 315 #endif /* CONFIG_DEBUG_VM */
 316
 317 static struct attribute *hugepage_attr[] = {
 318         &enabled_attr.attr,
 319         &defrag_attr.attr,
 320         &use_zero_page_attr.attr,
 321         &hpage_pmd_size_attr.attr,
 322 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
 323         &shmem_enabled_attr.attr,
 324 #endif
 325 #ifdef CONFIG_DEBUG_VM
 326         &debug_cow_attr.attr,
 327 #endif
 328         NULL,
 329 };
 330
 331 static const struct attribute_group hugepage_attr_group = {
 332         .attrs = hugepage_attr,
 333 };
 334
 335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 336 {
 337         int err;
 338
 339         *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
 340         if (unlikely(!*hugepage_kobj)) {
 341                 pr_err("failed to create transparent hugepage kobject\n");
 342                 return -ENOMEM;
 343         }
 344
 345         err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
 346         if (err) {
 347                 pr_err("failed to register transparent hugepage group\n");
 348                 goto delete_obj;
 349         }
 350
 351         err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
 352         if (err) {
 353                 pr_err("failed to register transparent hugepage group\n");
 354                 goto remove_hp_group;
 355         }
 356
 357         return 0;
 358
 359 remove_hp_group:
 360         sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
 361 delete_obj:
 362         kobject_put(*hugepage_kobj);
 363         return err;
 364 }
 365
 366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 367 {
 368         sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
 369         sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
 370         kobject_put(hugepage_kobj);
 371 }
 372 #else
 373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
 374 {
 375         return 0;
 376 }
 377
 378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 379 {
 380 }
 381 #endif /* CONFIG_SYSFS */
 382
 383 static int __init hugepage_init(void)
 384 {
 385         int err;
 386         struct kobject *hugepage_kobj;
 387
 388         if (!has_transparent_hugepage()) {
 389                 transparent_hugepage_flags = 0;
 390                 return -EINVAL;
 391         }
 392
 393         /*
 394          * hugepages can't be allocated by the buddy allocator
 395          */
 396         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
 397         /*
 398          * we use page->mapping and page->index in second tail page
 399          * as list_head: assuming THP order >= 2
 400          */
 401         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
 402
 403         err = hugepage_init_sysfs(&hugepage_kobj);
 404         if (err)
 405                 goto err_sysfs;
 406
 407         err = khugepaged_init();
 408         if (err)
 409                 goto err_slab;
 410
 411         err = register_shrinker(&huge_zero_page_shrinker);
 412         if (err)
 413                 goto err_hzp_shrinker;
 414         err = register_shrinker(&deferred_split_shrinker);
 415         if (err)
 416                 goto err_split_shrinker;
 417
 418         /*
 419          * By default disable transparent hugepages on smaller systems,
 420          * where the extra memory used could hurt more than TLB overhead
 421          * is likely to save.  The admin can still enable it through /sys.
 422          */
 423         if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
 424                 transparent_hugepage_flags = 0;
 425                 return 0;
 426         }
 427
 428         err = start_stop_khugepaged();
 429         if (err)
 430                 goto err_khugepaged;
 431
 432         return 0;
 433 err_khugepaged:
 434         unregister_shrinker(&deferred_split_shrinker);
 435 err_split_shrinker:
 436         unregister_shrinker(&huge_zero_page_shrinker);
 437 err_hzp_shrinker:
 438         khugepaged_destroy();
 439 err_slab:
 440         hugepage_exit_sysfs(hugepage_kobj);
 441 err_sysfs:
 442         return err;
 443 }
 444 subsys_initcall(hugepage_init);
 445
 446 static int __init setup_transparent_hugepage(char *str)
 447 {
 448         int ret = 0;
 449         if (!str)
 450                 goto out;
 451         if (!strcmp(str, "always")) {
 452                 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
 453                         &transparent_hugepage_flags);
 454                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 455                           &transparent_hugepage_flags);
 456                 ret = 1;
 457         } else if (!strcmp(str, "madvise")) {
 458                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 459                           &transparent_hugepage_flags);
 460                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 461                         &transparent_hugepage_flags);
 462                 ret = 1;
 463         } else if (!strcmp(str, "never")) {
 464                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 465                           &transparent_hugepage_flags);
 466                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 467                           &transparent_hugepage_flags);
 468                 ret = 1;
 469         }
 470 out:
 471         if (!ret)
 472                 pr_warn("transparent_hugepage= cannot parse, ignored\n");
 473         return ret;
 474 }
 475 __setup("transparent_hugepage=", setup_transparent_hugepage);
 476
 477 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 478 {
 479         if (likely(vma->vm_flags & VM_WRITE))
 480                 pmd = pmd_mkwrite(pmd);
 481         return pmd;
 482 }
 483
 484 static inline struct list_head *page_deferred_list(struct page *page)
 485 {
 486         /*
 487          * ->lru in the tail pages is occupied by compound_head.
 488          * Let's use ->mapping + ->index in the second tail page as list_head.
 489          */
 490         return (struct list_head *)&page[2].mapping;
 491 }
 492
 493 void prep_transhuge_page(struct page *page)
 494 {
 495         /*
 496          * we use page->mapping and page->indexlru in second tail page
 497          * as list_head: assuming THP order >= 2
 498          */
 499
 500         INIT_LIST_HEAD(page_deferred_list(page));
 501         set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
 502 }
 503
 504 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
 505                 loff_t off, unsigned long flags, unsigned long size)
 506 {
 507         unsigned long addr;
 508         loff_t off_end = off + len;
 509         loff_t off_align = round_up(off, size);
 510         unsigned long len_pad;
 511
 512         if (off_end <= off_align || (off_end - off_align) < size)
 513                 return 0;
 514
 515         len_pad = len + size;
 516         if (len_pad < len || (off + len_pad) < off)
 517                 return 0;
 518
 519         addr = current->mm->get_unmapped_area(filp, 0, len_pad,
 520                                               off >> PAGE_SHIFT, flags);
 521         if (IS_ERR_VALUE(addr))
 522                 return 0;
 523
 524         addr += (off - addr) & (size - 1);
 525         return addr;
 526 }
 527
 528 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 529                 unsigned long len, unsigned long pgoff, unsigned long flags)
 530 {
 531         loff_t off = (loff_t)pgoff << PAGE_SHIFT;
 532
 533         if (addr)
 534                 goto out;
 535         if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
 536                 goto out;
 537
 538         addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
 539         if (addr)
 540                 return addr;
 541
 542  out:
 543         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 544 }
 545 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
 546
 547 static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
 548                 gfp_t gfp)
 549 {
 550         struct vm_area_struct *vma = vmf->vma;
 551         struct mem_cgroup *memcg;
 552         pgtable_t pgtable;
 553         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 554         int ret = 0;
 555
 556         VM_BUG_ON_PAGE(!PageCompound(page), page);
 557
 558         if (mem_cgroup_try_charge(page, vma->vm_mm, gfp | __GFP_NORETRY, &memcg,
 559                                   true)) {
 560                 put_page(page);
 561                 count_vm_event(THP_FAULT_FALLBACK);
 562                 return VM_FAULT_FALLBACK;
 563         }
 564
 565         pgtable = pte_alloc_one(vma->vm_mm, haddr);
 566         if (unlikely(!pgtable)) {
 567                 ret = VM_FAULT_OOM;
 568                 goto release;
 569         }
 570
 571         clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
 572         /*
 573          * The memory barrier inside __SetPageUptodate makes sure that
 574          * clear_huge_page writes become visible before the set_pmd_at()
 575          * write.
 576          */
 577         __SetPageUptodate(page);
 578
 579         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 580         if (unlikely(!pmd_none(*vmf->pmd))) {
 581                 goto unlock_release;
 582         } else {
 583                 pmd_t entry;
 584
 585                 ret = check_stable_address_space(vma->vm_mm);
 586                 if (ret)
 587                         goto unlock_release;
 588
 589                 /* Deliver the page fault to userland */
 590                 if (userfaultfd_missing(vma)) {
 591                         int ret;
 592
 593                         spin_unlock(vmf->ptl);
 594                         mem_cgroup_cancel_charge(page, memcg, true);
 595                         put_page(page);
 596                         pte_free(vma->vm_mm, pgtable);
 597                         ret = handle_userfault(vmf, VM_UFFD_MISSING);
 598                         VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 599                         return ret;
 600                 }
 601
 602                 entry = mk_huge_pmd(page, vma->vm_page_prot);
 603                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 604                 page_add_new_anon_rmap(page, vma, haddr, true);
 605                 mem_cgroup_commit_charge(page, memcg, false, true);
 606                 lru_cache_add_active_or_unevictable(page, vma);
 607                 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
 608                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
 609                 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 610                 mm_inc_nr_ptes(vma->vm_mm);
 611                 spin_unlock(vmf->ptl);
 612                 count_vm_event(THP_FAULT_ALLOC);
 613         }
 614
 615         return 0;
 616 unlock_release:
 617         spin_unlock(vmf->ptl);
 618 release:
 619         if (pgtable)
 620                 pte_free(vma->vm_mm, pgtable);
 621         mem_cgroup_cancel_charge(page, memcg, true);
 622         put_page(page);
 623         return ret;
 624
 625 }
 626
 627 /*
 628  * always: directly stall for all thp allocations
 629  * defer: wake kswapd and fail if not immediately available
 630  * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
 631  *                fail if not immediately available
 632  * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
 633  *          available
 634  * never: never stall for any thp allocation
 635  */
 636 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
 637 {
 638         const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
 639
 640         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 641                 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
 642         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 643                 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
 644         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 645                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 646                                                              __GFP_KSWAPD_RECLAIM);
 647         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 648                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 649                                                              0);
 650         return GFP_TRANSHUGE_LIGHT;
 651 }
 652
 653 /* Caller must hold page table lock. */
 654 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 655                 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
 656                 struct page *zero_page)
 657 {
 658         pmd_t entry;
 659         if (!pmd_none(*pmd))
 660                 return false;
 661         entry = mk_pmd(zero_page, vma->vm_page_prot);
 662         entry = pmd_mkhuge(entry);
 663         if (pgtable)
 664                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 665         set_pmd_at(mm, haddr, pmd, entry);
 666         mm_inc_nr_ptes(mm);
 667         return true;
 668 }
 669
 670 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 671 {
 672         struct vm_area_struct *vma = vmf->vma;
 673         gfp_t gfp;
 674         struct page *page;
 675         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 676
 677         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
 678                 return VM_FAULT_FALLBACK;
 679         if (unlikely(anon_vma_prepare(vma)))
 680                 return VM_FAULT_OOM;
 681         if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
 682                 return VM_FAULT_OOM;
 683         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
 684                         !mm_forbids_zeropage(vma->vm_mm) &&
 685                         transparent_hugepage_use_zero_page()) {
 686                 pgtable_t pgtable;
 687                 struct page *zero_page;
 688                 bool set;
 689                 int ret;
 690                 pgtable = pte_alloc_one(vma->vm_mm, haddr);
 691                 if (unlikely(!pgtable))
 692                         return VM_FAULT_OOM;
 693                 zero_page = mm_get_huge_zero_page(vma->vm_mm);
 694                 if (unlikely(!zero_page)) {
 695                         pte_free(vma->vm_mm, pgtable);
 696                         count_vm_event(THP_FAULT_FALLBACK);
 697                         return VM_FAULT_FALLBACK;
 698                 }
 699                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 700                 ret = 0;
 701                 set = false;
 702                 if (pmd_none(*vmf->pmd)) {
 703                         ret = check_stable_address_space(vma->vm_mm);
 704                         if (ret) {
 705                                 spin_unlock(vmf->ptl);
 706                         } else if (userfaultfd_missing(vma)) {
 707                                 spin_unlock(vmf->ptl);
 708                                 ret = handle_userfault(vmf, VM_UFFD_MISSING);
 709                                 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 710                         } else {
 711                                 set_huge_zero_page(pgtable, vma->vm_mm, vma,
 712                                                    haddr, vmf->pmd, zero_page);
 713                                 spin_unlock(vmf->ptl);
 714                                 set = true;
 715                         }
 716                 } else
 717                         spin_unlock(vmf->ptl);
 718                 if (!set)
 719                         pte_free(vma->vm_mm, pgtable);
 720                 return ret;
 721         }
 722         gfp = alloc_hugepage_direct_gfpmask(vma);
 723         page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
 724         if (unlikely(!page)) {
 725                 count_vm_event(THP_FAULT_FALLBACK);
 726                 return VM_FAULT_FALLBACK;
 727         }
 728         prep_transhuge_page(page);
 729         return __do_huge_pmd_anonymous_page(vmf, page, gfp);
 730 }
 731
 732 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 733                 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
 734                 pgtable_t pgtable)
 735 {
 736         struct mm_struct *mm = vma->vm_mm;
 737         pmd_t entry;
 738         spinlock_t *ptl;
 739
 740         ptl = pmd_lock(mm, pmd);
 741         entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
 742         if (pfn_t_devmap(pfn))
 743                 entry = pmd_mkdevmap(entry);
 744         if (write) {
 745                 entry = pmd_mkyoung(pmd_mkdirty(entry));
 746                 entry = maybe_pmd_mkwrite(entry, vma);
 747         }
 748
 749         if (pgtable) {
 750                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 751                 mm_inc_nr_ptes(mm);
 752         }
 753
 754         set_pmd_at(mm, addr, pmd, entry);
 755         update_mmu_cache_pmd(vma, addr, pmd);
 756         spin_unlock(ptl);
 757 }
 758
 759 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 760                         pmd_t *pmd, pfn_t pfn, bool write)
 761 {
 762         pgprot_t pgprot = vma->vm_page_prot;
 763         pgtable_t pgtable = NULL;
 764         /*
 765          * If we had pmd_special, we could avoid all these restrictions,
 766          * but we need to be consistent with PTEs and architectures that
 767          * can't support a 'special' bit.
 768          */
 769         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 770         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 771                                                 (VM_PFNMAP|VM_MIXEDMAP));
 772         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 773         BUG_ON(!pfn_t_devmap(pfn));
 774
 775         if (addr < vma->vm_start || addr >= vma->vm_end)
 776                 return VM_FAULT_SIGBUS;
 777
 778         if (arch_needs_pgtable_deposit()) {
 779                 pgtable = pte_alloc_one(vma->vm_mm, addr);
 780                 if (!pgtable)
 781                         return VM_FAULT_OOM;
 782         }
 783
 784         track_pfn_insert(vma, &pgprot, pfn);
 785
 786         insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
 787         return VM_FAULT_NOPAGE;
 788 }
 789 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
 790
 791 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 792 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
 793 {
 794         if (likely(vma->vm_flags & VM_WRITE))
 795                 pud = pud_mkwrite(pud);
 796         return pud;
 797 }
 798
 799 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 800                 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
 801 {
 802         struct mm_struct *mm = vma->vm_mm;
 803         pud_t entry;
 804         spinlock_t *ptl;
 805
 806         ptl = pud_lock(mm, pud);
 807         entry = pud_mkhuge(pfn_t_pud(pfn, prot));
 808         if (pfn_t_devmap(pfn))
 809                 entry = pud_mkdevmap(entry);
 810         if (write) {
 811                 entry = pud_mkyoung(pud_mkdirty(entry));
 812                 entry = maybe_pud_mkwrite(entry, vma);
 813         }
 814         set_pud_at(mm, addr, pud, entry);
 815         update_mmu_cache_pud(vma, addr, pud);
 816         spin_unlock(ptl);
 817 }
 818
 819 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 820                         pud_t *pud, pfn_t pfn, bool write)
 821 {
 822         pgprot_t pgprot = vma->vm_page_prot;
 823         /*
 824          * If we had pud_special, we could avoid all these restrictions,
 825          * but we need to be consistent with PTEs and architectures that
 826          * can't support a 'special' bit.
 827          */
 828         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 829         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 830                                                 (VM_PFNMAP|VM_MIXEDMAP));
 831         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 832         BUG_ON(!pfn_t_devmap(pfn));
 833
 834         if (addr < vma->vm_start || addr >= vma->vm_end)
 835                 return VM_FAULT_SIGBUS;
 836
 837         track_pfn_insert(vma, &pgprot, pfn);
 838
 839         insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
 840         return VM_FAULT_NOPAGE;
 841 }
 842 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
 843 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 844
 845 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 846                 pmd_t *pmd, int flags)
 847 {
 848         pmd_t _pmd;
 849
 850         _pmd = pmd_mkyoung(*pmd);
 851         if (flags & FOLL_WRITE)
 852                 _pmd = pmd_mkdirty(_pmd);
 853         if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
 854                                 pmd, _pmd, flags & FOLL_WRITE))
 855                 update_mmu_cache_pmd(vma, addr, pmd);
 856 }
 857
 858 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 859                 pmd_t *pmd, int flags)
 860 {
 861         unsigned long pfn = pmd_pfn(*pmd);
 862         struct mm_struct *mm = vma->vm_mm;
 863         struct dev_pagemap *pgmap;
 864         struct page *page;
 865
 866         assert_spin_locked(pmd_lockptr(mm, pmd));
 867
 868         /*
 869          * When we COW a devmap PMD entry, we split it into PTEs, so we should
 870          * not be in this function with `flags & FOLL_COW` set.
 871          */
 872         WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
 873
 874         if (flags & FOLL_WRITE && !pmd_write(*pmd))
 875                 return NULL;
 876
 877         if (pmd_present(*pmd) && pmd_devmap(*pmd))
 878                 /* pass */;
 879         else
 880                 return NULL;
 881
 882         if (flags & FOLL_TOUCH)
 883                 touch_pmd(vma, addr, pmd, flags);
 884
 885         /*
 886          * device mapped pages can only be returned if the
 887          * caller will manage the page reference count.
 888          */
 889         if (!(flags & FOLL_GET))
 890                 return ERR_PTR(-EEXIST);
 891
 892         pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
 893         pgmap = get_dev_pagemap(pfn, NULL);
 894         if (!pgmap)
 895                 return ERR_PTR(-EFAULT);
 896         page = pfn_to_page(pfn);
 897         get_page(page);
 898         put_dev_pagemap(pgmap);
 899
 900         return page;
 901 }
 902
 903 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 904                   pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 905                   struct vm_area_struct *vma)
 906 {
 907         spinlock_t *dst_ptl, *src_ptl;
 908         struct page *src_page;
 909         pmd_t pmd;
 910         pgtable_t pgtable = NULL;
 911         int ret = -ENOMEM;
 912
 913         /* Skip if can be re-fill on fault */
 914         if (!vma_is_anonymous(vma))
 915                 return 0;
 916
 917         pgtable = pte_alloc_one(dst_mm, addr);
 918         if (unlikely(!pgtable))
 919                 goto out;
 920
 921         dst_ptl = pmd_lock(dst_mm, dst_pmd);
 922         src_ptl = pmd_lockptr(src_mm, src_pmd);
 923         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 924
 925         ret = -EAGAIN;
 926         pmd = *src_pmd;
 927
 928 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 929         if (unlikely(is_swap_pmd(pmd))) {
 930                 swp_entry_t entry = pmd_to_swp_entry(pmd);
 931
 932                 VM_BUG_ON(!is_pmd_migration_entry(pmd));
 933                 if (is_write_migration_entry(entry)) {
 934                         make_migration_entry_read(&entry);
 935                         pmd = swp_entry_to_pmd(entry);
 936                         if (pmd_swp_soft_dirty(*src_pmd))
 937                                 pmd = pmd_swp_mksoft_dirty(pmd);
 938                         set_pmd_at(src_mm, addr, src_pmd, pmd);
 939                 }
 940                 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 941                 mm_inc_nr_ptes(dst_mm);
 942                 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 943                 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 944                 ret = 0;
 945                 goto out_unlock;
 946         }
 947 #endif
 948
 949         if (unlikely(!pmd_trans_huge(pmd))) {
 950                 pte_free(dst_mm, pgtable);
 951                 goto out_unlock;
 952         }
 953         /*
 954          * When page table lock is held, the huge zero pmd should not be
 955          * under splitting since we don't split the page itself, only pmd to
 956          * a page table.
 957          */
 958         if (is_huge_zero_pmd(pmd)) {
 959                 struct page *zero_page;
 960                 /*
 961                  * get_huge_zero_page() will never allocate a new page here,
 962                  * since we already have a zero page to copy. It just takes a
 963                  * reference.
 964                  */
 965                 zero_page = mm_get_huge_zero_page(dst_mm);
 966                 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
 967                                 zero_page);
 968                 ret = 0;
 969                 goto out_unlock;
 970         }
 971
 972         src_page = pmd_page(pmd);
 973         VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
 974         get_page(src_page);
 975         page_dup_rmap(src_page, true);
 976         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 977         mm_inc_nr_ptes(dst_mm);
 978         pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 979
 980         pmdp_set_wrprotect(src_mm, addr, src_pmd);
 981         pmd = pmd_mkold(pmd_wrprotect(pmd));
 982         set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 983
 984         ret = 0;
 985 out_unlock:
 986         spin_unlock(src_ptl);
 987         spin_unlock(dst_ptl);
 988 out:
 989         return ret;
 990 }
 991
 992 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 993 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
 994                 pud_t *pud, int flags)
 995 {
 996         pud_t _pud;
 997
 998         _pud = pud_mkyoung(*pud);
 999         if (flags & FOLL_WRITE)
1000                 _pud = pud_mkdirty(_pud);
1001         if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1002                                 pud, _pud, flags & FOLL_WRITE))
1003                 update_mmu_cache_pud(vma, addr, pud);
1004 }
1005
1006 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1007                 pud_t *pud, int flags)
1008 {
1009         unsigned long pfn = pud_pfn(*pud);
1010         struct mm_struct *mm = vma->vm_mm;
1011         struct dev_pagemap *pgmap;
1012         struct page *page;
1013
1014         assert_spin_locked(pud_lockptr(mm, pud));
1015
1016         if (flags & FOLL_WRITE && !pud_write(*pud))
1017                 return NULL;
1018
1019         if (pud_present(*pud) && pud_devmap(*pud))
1020                 /* pass */;
1021         else
1022                 return NULL;
1023
1024         if (flags & FOLL_TOUCH)
1025                 touch_pud(vma, addr, pud, flags);
1026
1027         /*
1028          * device mapped pages can only be returned if the
1029          * caller will manage the page reference count.
1030          */
1031         if (!(flags & FOLL_GET))
1032                 return ERR_PTR(-EEXIST);
1033
1034         pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1035         pgmap = get_dev_pagemap(pfn, NULL);
1036         if (!pgmap)
1037                 return ERR_PTR(-EFAULT);
1038         page = pfn_to_page(pfn);
1039         get_page(page);
1040         put_dev_pagemap(pgmap);
1041
1042         return page;
1043 }
1044
1045 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046                   pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1047                   struct vm_area_struct *vma)
1048 {
1049         spinlock_t *dst_ptl, *src_ptl;
1050         pud_t pud;
1051         int ret;
1052
1053         dst_ptl = pud_lock(dst_mm, dst_pud);
1054         src_ptl = pud_lockptr(src_mm, src_pud);
1055         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1056
1057         ret = -EAGAIN;
1058         pud = *src_pud;
1059         if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1060                 goto out_unlock;
1061
1062         /*
1063          * When page table lock is held, the huge zero pud should not be
1064          * under splitting since we don't split the page itself, only pud to
1065          * a page table.
1066          */
1067         if (is_huge_zero_pud(pud)) {
1068                 /* No huge zero pud yet */
1069         }
1070
1071         pudp_set_wrprotect(src_mm, addr, src_pud);
1072         pud = pud_mkold(pud_wrprotect(pud));
1073         set_pud_at(dst_mm, addr, dst_pud, pud);
1074
1075         ret = 0;
1076 out_unlock:
1077         spin_unlock(src_ptl);
1078         spin_unlock(dst_ptl);
1079         return ret;
1080 }
1081
1082 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1083 {
1084         pud_t entry;
1085         unsigned long haddr;
1086         bool write = vmf->flags & FAULT_FLAG_WRITE;
1087
1088         vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1089         if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1090                 goto unlock;
1091
1092         entry = pud_mkyoung(orig_pud);
1093         if (write)
1094                 entry = pud_mkdirty(entry);
1095         haddr = vmf->address & HPAGE_PUD_MASK;
1096         if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1097                 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1098
1099 unlock:
1100         spin_unlock(vmf->ptl);
1101 }
1102 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1103
1104 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1105 {
1106         pmd_t entry;
1107         unsigned long haddr;
1108         bool write = vmf->flags & FAULT_FLAG_WRITE;
1109
1110         vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1111         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1112                 goto unlock;
1113
1114         entry = pmd_mkyoung(orig_pmd);
1115         if (write)
1116                 entry = pmd_mkdirty(entry);
1117         haddr = vmf->address & HPAGE_PMD_MASK;
1118         if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1119                 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1120
1121 unlock:
1122         spin_unlock(vmf->ptl);
1123 }
1124
1125 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1126                 struct page *page)
1127 {
1128         struct vm_area_struct *vma = vmf->vma;
1129         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1130         struct mem_cgroup *memcg;
1131         pgtable_t pgtable;
1132         pmd_t _pmd;
1133         int ret = 0, i;
1134         struct page **pages;
1135         unsigned long mmun_start;       /* For mmu_notifiers */
1136         unsigned long mmun_end;         /* For mmu_notifiers */
1137
1138         pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1139                         GFP_KERNEL);
1140         if (unlikely(!pages)) {
1141                 ret |= VM_FAULT_OOM;
1142                 goto out;
1143         }
1144
1145         for (i = 0; i < HPAGE_PMD_NR; i++) {
1146                 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1147                                                vmf->address, page_to_nid(page));
1148                 if (unlikely(!pages[i] ||
1149                              mem_cgroup_try_charge(pages[i], vma->vm_mm,
1150                                      GFP_KERNEL, &memcg, false))) {
1151                         if (pages[i])
1152                                 put_page(pages[i]);
1153                         while (--i >= 0) {
1154                                 memcg = (void *)page_private(pages[i]);
1155                                 set_page_private(pages[i], 0);
1156                                 mem_cgroup_cancel_charge(pages[i], memcg,
1157                                                 false);
1158                                 put_page(pages[i]);
1159                         }
1160                         kfree(pages);
1161                         ret |= VM_FAULT_OOM;
1162                         goto out;
1163                 }
1164                 set_page_private(pages[i], (unsigned long)memcg);
1165         }
1166
1167         for (i = 0; i < HPAGE_PMD_NR; i++) {
1168                 copy_user_highpage(pages[i], page + i,
1169                                    haddr + PAGE_SIZE * i, vma);
1170                 __SetPageUptodate(pages[i]);
1171                 cond_resched();
1172         }
1173
1174         mmun_start = haddr;
1175         mmun_end   = haddr + HPAGE_PMD_SIZE;
1176         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1177
1178         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1179         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1180                 goto out_free_pages;
1181         VM_BUG_ON_PAGE(!PageHead(page), page);
1182
1183         /*
1184          * Leave pmd empty until pte is filled note we must notify here as
1185          * concurrent CPU thread might write to new page before the call to
1186          * mmu_notifier_invalidate_range_end() happens which can lead to a
1187          * device seeing memory write in different order than CPU.
1188          *
1189          * See Documentation/vm/mmu_notifier.txt
1190          */
1191         pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1192
1193         pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1194         pmd_populate(vma->vm_mm, &_pmd, pgtable);
1195
1196         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1197                 pte_t entry;
1198                 entry = mk_pte(pages[i], vma->vm_page_prot);
1199                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1200                 memcg = (void *)page_private(pages[i]);
1201                 set_page_private(pages[i], 0);
1202                 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1203                 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1204                 lru_cache_add_active_or_unevictable(pages[i], vma);
1205                 vmf->pte = pte_offset_map(&_pmd, haddr);
1206                 VM_BUG_ON(!pte_none(*vmf->pte));
1207                 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1208                 pte_unmap(vmf->pte);
1209         }
1210         kfree(pages);
1211
1212         smp_wmb(); /* make pte visible before pmd */
1213         pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1214         page_remove_rmap(page, true);
1215         spin_unlock(vmf->ptl);
1216
1217         /*
1218          * No need to double call mmu_notifier->invalidate_range() callback as
1219          * the above pmdp_huge_clear_flush_notify() did already call it.
1220          */
1221         mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1222                                                 mmun_end);
1223
1224         ret |= VM_FAULT_WRITE;
1225         put_page(page);
1226
1227 out:
1228         return ret;
1229
1230 out_free_pages:
1231         spin_unlock(vmf->ptl);
1232         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1233         for (i = 0; i < HPAGE_PMD_NR; i++) {
1234                 memcg = (void *)page_private(pages[i]);
1235                 set_page_private(pages[i], 0);
1236                 mem_cgroup_cancel_charge(pages[i], memcg, false);
1237                 put_page(pages[i]);
1238         }
1239         kfree(pages);
1240         goto out;
1241 }
1242
1243 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1244 {
1245         struct vm_area_struct *vma = vmf->vma;
1246         struct page *page = NULL, *new_page;
1247         struct mem_cgroup *memcg;
1248         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1249         unsigned long mmun_start;       /* For mmu_notifiers */
1250         unsigned long mmun_end;         /* For mmu_notifiers */
1251         gfp_t huge_gfp;                 /* for allocation and charge */
1252         int ret = 0;
1253
1254         vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1255         VM_BUG_ON_VMA(!vma->anon_vma, vma);
1256         if (is_huge_zero_pmd(orig_pmd))
1257                 goto alloc;
1258         spin_lock(vmf->ptl);
1259         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1260                 goto out_unlock;
1261
1262         page = pmd_page(orig_pmd);
1263         VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1264         /*
1265          * We can only reuse the page if nobody else maps the huge page or it's
1266          * part.
1267          */
1268         if (!trylock_page(page)) {
1269                 get_page(page);
1270                 spin_unlock(vmf->ptl);
1271                 lock_page(page);
1272                 spin_lock(vmf->ptl);
1273                 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1274                         unlock_page(page);
1275                         put_page(page);
1276                         goto out_unlock;
1277                 }
1278                 put_page(page);
1279         }
1280         if (reuse_swap_page(page, NULL)) {
1281                 pmd_t entry;
1282                 entry = pmd_mkyoung(orig_pmd);
1283                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1284                 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry,  1))
1285                         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1286                 ret |= VM_FAULT_WRITE;
1287                 unlock_page(page);
1288                 goto out_unlock;
1289         }
1290         unlock_page(page);
1291         get_page(page);
1292         spin_unlock(vmf->ptl);
1293 alloc:
1294         if (transparent_hugepage_enabled(vma) &&
1295             !transparent_hugepage_debug_cow()) {
1296                 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1297                 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1298         } else
1299                 new_page = NULL;
1300
1301         if (likely(new_page)) {
1302                 prep_transhuge_page(new_page);
1303         } else {
1304                 if (!page) {
1305                         split_huge_pmd(vma, vmf->pmd, vmf->address);
1306                         ret |= VM_FAULT_FALLBACK;
1307                 } else {
1308                         ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1309                         if (ret & VM_FAULT_OOM) {
1310                                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1311                                 ret |= VM_FAULT_FALLBACK;
1312                         }
1313                         put_page(page);
1314                 }
1315                 count_vm_event(THP_FAULT_FALLBACK);
1316                 goto out;
1317         }
1318
1319         if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1320                                 huge_gfp | __GFP_NORETRY, &memcg, true))) {
1321                 put_page(new_page);
1322                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1323                 if (page)
1324                         put_page(page);
1325                 ret |= VM_FAULT_FALLBACK;
1326                 count_vm_event(THP_FAULT_FALLBACK);
1327                 goto out;
1328         }
1329
1330         count_vm_event(THP_FAULT_ALLOC);
1331
1332         if (!page)
1333                 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1334         else
1335                 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1336         __SetPageUptodate(new_page);
1337
1338         mmun_start = haddr;
1339         mmun_end   = haddr + HPAGE_PMD_SIZE;
1340         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1341
1342         spin_lock(vmf->ptl);
1343         if (page)
1344                 put_page(page);
1345         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1346                 spin_unlock(vmf->ptl);
1347                 mem_cgroup_cancel_charge(new_page, memcg, true);
1348                 put_page(new_page);
1349                 goto out_mn;
1350         } else {
1351                 pmd_t entry;
1352                 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1353                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1354                 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1355                 page_add_new_anon_rmap(new_page, vma, haddr, true);
1356                 mem_cgroup_commit_charge(new_page, memcg, false, true);
1357                 lru_cache_add_active_or_unevictable(new_page, vma);
1358                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1359                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1360                 if (!page) {
1361                         add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1362                 } else {
1363                         VM_BUG_ON_PAGE(!PageHead(page), page);
1364                         page_remove_rmap(page, true);
1365                         put_page(page);
1366                 }
1367                 ret |= VM_FAULT_WRITE;
1368         }
1369         spin_unlock(vmf->ptl);
1370 out_mn:
1371         /*
1372          * No need to double call mmu_notifier->invalidate_range() callback as
1373          * the above pmdp_huge_clear_flush_notify() did already call it.
1374          */
1375         mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1376                                                mmun_end);
1377 out:
1378         return ret;
1379 out_unlock:
1380         spin_unlock(vmf->ptl);
1381         return ret;
1382 }
1383
1384 /*
1385  * FOLL_FORCE can write to even unwritable pmd's, but only
1386  * after we've gone through a COW cycle and they are dirty.
1387  */
1388 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1389 {
1390         return pmd_write(pmd) ||
1391                ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1392 }
1393
1394 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1395                                    unsigned long addr,
1396                                    pmd_t *pmd,
1397                                    unsigned int flags)
1398 {
1399         struct mm_struct *mm = vma->vm_mm;
1400         struct page *page = NULL;
1401
1402         assert_spin_locked(pmd_lockptr(mm, pmd));
1403
1404         if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1405                 goto out;
1406
1407         /* Avoid dumping huge zero page */
1408         if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1409                 return ERR_PTR(-EFAULT);
1410
1411         /* Full NUMA hinting faults to serialise migration in fault paths */
1412         if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1413                 goto out;
1414
1415         page = pmd_page(*pmd);
1416         VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1417         if (flags & FOLL_TOUCH)
1418                 touch_pmd(vma, addr, pmd, flags);
1419         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1420                 /*
1421                  * We don't mlock() pte-mapped THPs. This way we can avoid
1422                  * leaking mlocked pages into non-VM_LOCKED VMAs.
1423                  *
1424                  * For anon THP:
1425                  *
1426                  * In most cases the pmd is the only mapping of the page as we
1427                  * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1428                  * writable private mappings in populate_vma_page_range().
1429                  *
1430                  * The only scenario when we have the page shared here is if we
1431                  * mlocking read-only mapping shared over fork(). We skip
1432                  * mlocking such pages.
1433                  *
1434                  * For file THP:
1435                  *
1436                  * We can expect PageDoubleMap() to be stable under page lock:
1437                  * for file pages we set it in page_add_file_rmap(), which
1438                  * requires page to be locked.
1439                  */
1440
1441                 if (PageAnon(page) && compound_mapcount(page) != 1)
1442                         goto skip_mlock;
1443                 if (PageDoubleMap(page) || !page->mapping)
1444                         goto skip_mlock;
1445                 if (!trylock_page(page))
1446                         goto skip_mlock;
1447                 lru_add_drain();
1448                 if (page->mapping && !PageDoubleMap(page))
1449                         mlock_vma_page(page);
1450                 unlock_page(page);
1451         }
1452 skip_mlock:
1453         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1454         VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1455         if (flags & FOLL_GET)
1456                 get_page(page);
1457
1458 out:
1459         return page;
1460 }
1461
1462 /* NUMA hinting page fault entry point for trans huge pmds */
1463 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1464 {
1465         struct vm_area_struct *vma = vmf->vma;
1466         struct anon_vma *anon_vma = NULL;
1467         struct page *page;
1468         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1469         int page_nid = -1, this_nid = numa_node_id();
1470         int target_nid, last_cpupid = -1;
1471         bool page_locked;
1472         bool migrated = false;
1473         bool was_writable;
1474         int flags = 0;
1475
1476         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1477         if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1478                 goto out_unlock;
1479
1480         /*
1481          * If there are potential migrations, wait for completion and retry
1482          * without disrupting NUMA hinting information. Do not relock and
1483          * check_same as the page may no longer be mapped.
1484          */
1485         if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1486                 page = pmd_page(*vmf->pmd);
1487                 if (!get_page_unless_zero(page))
1488                         goto out_unlock;
1489                 spin_unlock(vmf->ptl);
1490                 wait_on_page_locked(page);
1491                 put_page(page);
1492                 goto out;
1493         }
1494
1495         page = pmd_page(pmd);
1496         BUG_ON(is_huge_zero_page(page));
1497         page_nid = page_to_nid(page);
1498         last_cpupid = page_cpupid_last(page);
1499         count_vm_numa_event(NUMA_HINT_FAULTS);
1500         if (page_nid == this_nid) {
1501                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1502                 flags |= TNF_FAULT_LOCAL;
1503         }
1504
1505         /* See similar comment in do_numa_page for explanation */
1506         if (!pmd_savedwrite(pmd))
1507                 flags |= TNF_NO_GROUP;
1508
1509         /*
1510          * Acquire the page lock to serialise THP migrations but avoid dropping
1511          * page_table_lock if at all possible
1512          */
1513         page_locked = trylock_page(page);
1514         target_nid = mpol_misplaced(page, vma, haddr);
1515         if (target_nid == -1) {
1516                 /* If the page was locked, there are no parallel migrations */
1517                 if (page_locked)
1518                         goto clear_pmdnuma;
1519         }
1520
1521         /* Migration could have started since the pmd_trans_migrating check */
1522         if (!page_locked) {
1523                 page_nid = -1;
1524                 if (!get_page_unless_zero(page))
1525                         goto out_unlock;
1526                 spin_unlock(vmf->ptl);
1527                 wait_on_page_locked(page);
1528                 put_page(page);
1529                 goto out;
1530         }
1531
1532         /*
1533          * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1534          * to serialises splits
1535          */
1536         get_page(page);
1537         spin_unlock(vmf->ptl);
1538         anon_vma = page_lock_anon_vma_read(page);
1539
1540         /* Confirm the PMD did not change while page_table_lock was released */
1541         spin_lock(vmf->ptl);
1542         if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1543                 unlock_page(page);
1544                 put_page(page);
1545                 page_nid = -1;
1546                 goto out_unlock;
1547         }
1548
1549         /* Bail if we fail to protect against THP splits for any reason */
1550         if (unlikely(!anon_vma)) {
1551                 put_page(page);
1552                 page_nid = -1;
1553                 goto clear_pmdnuma;
1554         }
1555
1556         /*
1557          * Since we took the NUMA fault, we must have observed the !accessible
1558          * bit. Make sure all other CPUs agree with that, to avoid them
1559          * modifying the page we're about to migrate.
1560          *
1561          * Must be done under PTL such that we'll observe the relevant
1562          * inc_tlb_flush_pending().
1563          *
1564          * We are not sure a pending tlb flush here is for a huge page
1565          * mapping or not. Hence use the tlb range variant
1566          */
1567         if (mm_tlb_flush_pending(vma->vm_mm))
1568                 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1569
1570         /*
1571          * Migrate the THP to the requested node, returns with page unlocked
1572          * and access rights restored.
1573          */
1574         spin_unlock(vmf->ptl);
1575
1576         migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1577                                 vmf->pmd, pmd, vmf->address, page, target_nid);
1578         if (migrated) {
1579                 flags |= TNF_MIGRATED;
1580                 page_nid = target_nid;
1581         } else
1582                 flags |= TNF_MIGRATE_FAIL;
1583
1584         goto out;
1585 clear_pmdnuma:
1586         BUG_ON(!PageLocked(page));
1587         was_writable = pmd_savedwrite(pmd);
1588         pmd = pmd_modify(pmd, vma->vm_page_prot);
1589         pmd = pmd_mkyoung(pmd);
1590         if (was_writable)
1591                 pmd = pmd_mkwrite(pmd);
1592         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1593         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1594         unlock_page(page);
1595 out_unlock:
1596         spin_unlock(vmf->ptl);
1597
1598 out:
1599         if (anon_vma)
1600                 page_unlock_anon_vma_read(anon_vma);
1601
1602         if (page_nid != -1)
1603                 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1604                                 flags);
1605
1606         return 0;
1607 }
1608
1609 /*
1610  * Return true if we do MADV_FREE successfully on entire pmd page.
1611  * Otherwise, return false.
1612  */
1613 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1614                 pmd_t *pmd, unsigned long addr, unsigned long next)
1615 {
1616         spinlock_t *ptl;
1617         pmd_t orig_pmd;
1618         struct page *page;
1619         struct mm_struct *mm = tlb->mm;
1620         bool ret = false;
1621
1622         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1623
1624         ptl = pmd_trans_huge_lock(pmd, vma);
1625         if (!ptl)
1626                 goto out_unlocked;
1627
1628         orig_pmd = *pmd;
1629         if (is_huge_zero_pmd(orig_pmd))
1630                 goto out;
1631
1632         if (unlikely(!pmd_present(orig_pmd))) {
1633                 VM_BUG_ON(thp_migration_supported() &&
1634                                   !is_pmd_migration_entry(orig_pmd));
1635                 goto out;
1636         }
1637
1638         page = pmd_page(orig_pmd);
1639         /*
1640          * If other processes are mapping this page, we couldn't discard
1641          * the page unless they all do MADV_FREE so let's skip the page.
1642          */
1643         if (page_mapcount(page) != 1)
1644                 goto out;
1645
1646         if (!trylock_page(page))
1647                 goto out;
1648
1649         /*
1650          * If user want to discard part-pages of THP, split it so MADV_FREE
1651          * will deactivate only them.
1652          */
1653         if (next - addr != HPAGE_PMD_SIZE) {
1654                 get_page(page);
1655                 spin_unlock(ptl);
1656                 split_huge_page(page);
1657                 unlock_page(page);
1658                 put_page(page);
1659                 goto out_unlocked;
1660         }
1661
1662         if (PageDirty(page))
1663                 ClearPageDirty(page);
1664         unlock_page(page);
1665
1666         if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1667                 pmdp_invalidate(vma, addr, pmd);
1668                 orig_pmd = pmd_mkold(orig_pmd);
1669                 orig_pmd = pmd_mkclean(orig_pmd);
1670
1671                 set_pmd_at(mm, addr, pmd, orig_pmd);
1672                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1673         }
1674
1675         mark_page_lazyfree(page);
1676         ret = true;
1677 out:
1678         spin_unlock(ptl);
1679 out_unlocked:
1680         return ret;
1681 }
1682
1683 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1684 {
1685         pgtable_t pgtable;
1686
1687         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1688         pte_free(mm, pgtable);
1689         mm_dec_nr_ptes(mm);
1690 }
1691
1692 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1693                  pmd_t *pmd, unsigned long addr)
1694 {
1695         pmd_t orig_pmd;
1696         spinlock_t *ptl;
1697
1698         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1699
1700         ptl = __pmd_trans_huge_lock(pmd, vma);
1701         if (!ptl)
1702                 return 0;
1703         /*
1704          * For architectures like ppc64 we look at deposited pgtable
1705          * when calling pmdp_huge_get_and_clear. So do the
1706          * pgtable_trans_huge_withdraw after finishing pmdp related
1707          * operations.
1708          */
1709         orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1710                         tlb->fullmm);
1711         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1712         if (vma_is_dax(vma)) {
1713                 if (arch_needs_pgtable_deposit())
1714                         zap_deposited_table(tlb->mm, pmd);
1715                 spin_unlock(ptl);
1716                 if (is_huge_zero_pmd(orig_pmd))
1717                         tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1718         } else if (is_huge_zero_pmd(orig_pmd)) {
1719                 zap_deposited_table(tlb->mm, pmd);
1720                 spin_unlock(ptl);
1721                 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1722         } else {
1723                 struct page *page = NULL;
1724                 int flush_needed = 1;
1725
1726                 if (pmd_present(orig_pmd)) {
1727                         page = pmd_page(orig_pmd);
1728                         page_remove_rmap(page, true);
1729                         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1730                         VM_BUG_ON_PAGE(!PageHead(page), page);
1731                 } else if (thp_migration_supported()) {
1732                         swp_entry_t entry;
1733
1734                         VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1735                         entry = pmd_to_swp_entry(orig_pmd);
1736                         page = pfn_to_page(swp_offset(entry));
1737                         flush_needed = 0;
1738                 } else
1739                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1740
1741                 if (PageAnon(page)) {
1742                         zap_deposited_table(tlb->mm, pmd);
1743                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1744                 } else {
1745                         if (arch_needs_pgtable_deposit())
1746                                 zap_deposited_table(tlb->mm, pmd);
1747                         add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1748                 }
1749
1750                 spin_unlock(ptl);
1751                 if (flush_needed)
1752                         tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1753         }
1754         return 1;
1755 }
1756
1757 #ifndef pmd_move_must_withdraw
1758 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1759                                          spinlock_t *old_pmd_ptl,
1760                                          struct vm_area_struct *vma)
1761 {
1762         /*
1763          * With split pmd lock we also need to move preallocated
1764          * PTE page table if new_pmd is on different PMD page table.
1765          *
1766          * We also don't deposit and withdraw tables for file pages.
1767          */
1768         return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1769 }
1770 #endif
1771
1772 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1773 {
1774 #ifdef CONFIG_MEM_SOFT_DIRTY
1775         if (unlikely(is_pmd_migration_entry(pmd)))
1776                 pmd = pmd_swp_mksoft_dirty(pmd);
1777         else if (pmd_present(pmd))
1778                 pmd = pmd_mksoft_dirty(pmd);
1779 #endif
1780         return pmd;
1781 }
1782
1783 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1784                   unsigned long new_addr, unsigned long old_end,
1785                   pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1786 {
1787         spinlock_t *old_ptl, *new_ptl;
1788         pmd_t pmd;
1789         struct mm_struct *mm = vma->vm_mm;
1790         bool force_flush = false;
1791
1792         if ((old_addr & ~HPAGE_PMD_MASK) ||
1793             (new_addr & ~HPAGE_PMD_MASK) ||
1794             old_end - old_addr < HPAGE_PMD_SIZE)
1795                 return false;
1796
1797         /*
1798          * The destination pmd shouldn't be established, free_pgtables()
1799          * should have release it.
1800          */
1801         if (WARN_ON(!pmd_none(*new_pmd))) {
1802                 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1803                 return false;
1804         }
1805
1806         /*
1807          * We don't have to worry about the ordering of src and dst
1808          * ptlocks because exclusive mmap_sem prevents deadlock.
1809          */
1810         old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1811         if (old_ptl) {
1812                 new_ptl = pmd_lockptr(mm, new_pmd);
1813                 if (new_ptl != old_ptl)
1814                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1815                 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1816                 if (pmd_present(pmd) && pmd_dirty(pmd))
1817                         force_flush = true;
1818                 VM_BUG_ON(!pmd_none(*new_pmd));
1819
1820                 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1821                         pgtable_t pgtable;
1822                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1823                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1824                 }
1825                 pmd = move_soft_dirty_pmd(pmd);
1826                 set_pmd_at(mm, new_addr, new_pmd, pmd);
1827                 if (new_ptl != old_ptl)
1828                         spin_unlock(new_ptl);
1829                 if (force_flush)
1830                         flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1831                 else
1832                         *need_flush = true;
1833                 spin_unlock(old_ptl);
1834                 return true;
1835         }
1836         return false;
1837 }
1838
1839 /*
1840  * Returns
1841  *  - 0 if PMD could not be locked
1842  *  - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1843  *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
1844  */
1845 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1846                 unsigned long addr, pgprot_t newprot, int prot_numa)
1847 {
1848         struct mm_struct *mm = vma->vm_mm;
1849         spinlock_t *ptl;
1850         pmd_t entry;
1851         bool preserve_write;
1852         int ret;
1853
1854         ptl = __pmd_trans_huge_lock(pmd, vma);
1855         if (!ptl)
1856                 return 0;
1857
1858         preserve_write = prot_numa && pmd_write(*pmd);
1859         ret = 1;
1860
1861 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1862         if (is_swap_pmd(*pmd)) {
1863                 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1864
1865                 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1866                 if (is_write_migration_entry(entry)) {
1867                         pmd_t newpmd;
1868                         /*
1869                          * A protection check is difficult so
1870                          * just be safe and disable write
1871                          */
1872                         make_migration_entry_read(&entry);
1873                         newpmd = swp_entry_to_pmd(entry);
1874                         if (pmd_swp_soft_dirty(*pmd))
1875                                 newpmd = pmd_swp_mksoft_dirty(newpmd);
1876                         set_pmd_at(mm, addr, pmd, newpmd);
1877                 }
1878                 goto unlock;
1879         }
1880 #endif
1881
1882         /*
1883          * Avoid trapping faults against the zero page. The read-only
1884          * data is likely to be read-cached on the local CPU and
1885          * local/remote hits to the zero page are not interesting.
1886          */
1887         if (prot_numa && is_huge_zero_pmd(*pmd))
1888                 goto unlock;
1889
1890         if (prot_numa && pmd_protnone(*pmd))
1891                 goto unlock;
1892
1893         /*
1894          * In case prot_numa, we are under down_read(mmap_sem). It's critical
1895          * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1896          * which is also under down_read(mmap_sem):
1897          *
1898          *      CPU0:                           CPU1:
1899          *                              change_huge_pmd(prot_numa=1)
1900          *                               pmdp_huge_get_and_clear_notify()
1901          * madvise_dontneed()
1902          *  zap_pmd_range()
1903          *   pmd_trans_huge(*pmd) == 0 (without ptl)
1904          *   // skip the pmd
1905          *                               set_pmd_at();
1906          *                               // pmd is re-established
1907          *
1908          * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1909          * which may break userspace.
1910          *
1911          * pmdp_invalidate() is required to make sure we don't miss
1912          * dirty/young flags set by hardware.
1913          */
1914         entry = pmdp_invalidate(vma, addr, pmd);
1915
1916         entry = pmd_modify(entry, newprot);
1917         if (preserve_write)
1918                 entry = pmd_mk_savedwrite(entry);
1919         ret = HPAGE_PMD_NR;
1920         set_pmd_at(mm, addr, pmd, entry);
1921         BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1922 unlock:
1923         spin_unlock(ptl);
1924         return ret;
1925 }
1926
1927 /*
1928  * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1929  *
1930  * Note that if it returns page table lock pointer, this routine returns without
1931  * unlocking page table lock. So callers must unlock it.
1932  */
1933 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1934 {
1935         spinlock_t *ptl;
1936         ptl = pmd_lock(vma->vm_mm, pmd);
1937         if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1938                         pmd_devmap(*pmd)))
1939                 return ptl;
1940         spin_unlock(ptl);
1941         return NULL;
1942 }
1943
1944 /*
1945  * Returns true if a given pud maps a thp, false otherwise.
1946  *
1947  * Note that if it returns true, this routine returns without unlocking page
1948  * table lock. So callers must unlock it.
1949  */
1950 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1951 {
1952         spinlock_t *ptl;
1953
1954         ptl = pud_lock(vma->vm_mm, pud);
1955         if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1956                 return ptl;
1957         spin_unlock(ptl);
1958         return NULL;
1959 }
1960
1961 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1962 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1963                  pud_t *pud, unsigned long addr)
1964 {
1965         pud_t orig_pud;
1966         spinlock_t *ptl;
1967
1968         ptl = __pud_trans_huge_lock(pud, vma);
1969         if (!ptl)
1970                 return 0;
1971         /*
1972          * For architectures like ppc64 we look at deposited pgtable
1973          * when calling pudp_huge_get_and_clear. So do the
1974          * pgtable_trans_huge_withdraw after finishing pudp related
1975          * operations.
1976          */
1977         orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1978                         tlb->fullmm);
1979         tlb_remove_pud_tlb_entry(tlb, pud, addr);
1980         if (vma_is_dax(vma)) {
1981                 spin_unlock(ptl);
1982                 /* No zero page support yet */
1983         } else {
1984                 /* No support for anonymous PUD pages yet */
1985                 BUG();
1986         }
1987         return 1;
1988 }
1989
1990 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1991                 unsigned long haddr)
1992 {
1993         VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1994         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1995         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1996         VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1997
1998         count_vm_event(THP_SPLIT_PUD);
1999
2000         pudp_huge_clear_flush_notify(vma, haddr, pud);
2001 }
2002
2003 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2004                 unsigned long address)
2005 {
2006         spinlock_t *ptl;
2007         struct mm_struct *mm = vma->vm_mm;
2008         unsigned long haddr = address & HPAGE_PUD_MASK;
2009
2010         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2011         ptl = pud_lock(mm, pud);
2012         if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2013                 goto out;
2014         __split_huge_pud_locked(vma, pud, haddr);
2015
2016 out:
2017         spin_unlock(ptl);
2018         /*
2019          * No need to double call mmu_notifier->invalidate_range() callback as
2020          * the above pudp_huge_clear_flush_notify() did already call it.
2021          */
2022         mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2023                                                HPAGE_PUD_SIZE);
2024 }
2025 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2026
2027 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2028                 unsigned long haddr, pmd_t *pmd)
2029 {
2030         struct mm_struct *mm = vma->vm_mm;
2031         pgtable_t pgtable;
2032         pmd_t _pmd;
2033         int i;
2034
2035         /*
2036          * Leave pmd empty until pte is filled note that it is fine to delay
2037          * notification until mmu_notifier_invalidate_range_end() as we are
2038          * replacing a zero pmd write protected page with a zero pte write
2039          * protected page.
2040          *
2041          * See Documentation/vm/mmu_notifier.txt
2042          */
2043         pmdp_huge_clear_flush(vma, haddr, pmd);
2044
2045         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2046         pmd_populate(mm, &_pmd, pgtable);
2047
2048         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2049                 pte_t *pte, entry;
2050                 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2051                 entry = pte_mkspecial(entry);
2052                 pte = pte_offset_map(&_pmd, haddr);
2053                 VM_BUG_ON(!pte_none(*pte));
2054                 set_pte_at(mm, haddr, pte, entry);
2055                 pte_unmap(pte);
2056         }
2057         smp_wmb(); /* make pte visible before pmd */
2058         pmd_populate(mm, pmd, pgtable);
2059 }
2060
2061 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2062                 unsigned long haddr, bool freeze)
2063 {
2064         struct mm_struct *mm = vma->vm_mm;
2065         struct page *page;
2066         pgtable_t pgtable;
2067         pmd_t old_pmd, _pmd;
2068         bool young, write, soft_dirty, pmd_migration = false;
2069         unsigned long addr;
2070         int i;
2071
2072         VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2073         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2074         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2075         VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2076                                 && !pmd_devmap(*pmd));
2077
2078         count_vm_event(THP_SPLIT_PMD);
2079
2080         if (!vma_is_anonymous(vma)) {
2081                 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2082                 /*
2083                  * We are going to unmap this huge page. So
2084                  * just go ahead and zap it
2085                  */
2086                 if (arch_needs_pgtable_deposit())
2087                         zap_deposited_table(mm, pmd);
2088                 if (vma_is_dax(vma))
2089                         return;
2090                 page = pmd_page(_pmd);
2091                 if (!PageReferenced(page) && pmd_young(_pmd))
2092                         SetPageReferenced(page);
2093                 page_remove_rmap(page, true);
2094                 put_page(page);
2095                 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2096                 return;
2097         } else if (is_huge_zero_pmd(*pmd)) {
2098                 /*
2099                  * FIXME: Do we want to invalidate secondary mmu by calling
2100                  * mmu_notifier_invalidate_range() see comments below inside
2101                  * __split_huge_pmd() ?
2102                  *
2103                  * We are going from a zero huge page write protected to zero
2104                  * small page also write protected so it does not seems useful
2105                  * to invalidate secondary mmu at this time.
2106                  */
2107                 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2108         }
2109
2110         /*
2111          * Up to this point the pmd is present and huge and userland has the
2112          * whole access to the hugepage during the split (which happens in
2113          * place). If we overwrite the pmd with the not-huge version pointing
2114          * to the pte here (which of course we could if all CPUs were bug
2115          * free), userland could trigger a small page size TLB miss on the
2116          * small sized TLB while the hugepage TLB entry is still established in
2117          * the huge TLB. Some CPU doesn't like that.
2118          * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2119          * 383 on page 93. Intel should be safe but is also warns that it's
2120          * only safe if the permission and cache attributes of the two entries
2121          * loaded in the two TLB is identical (which should be the case here).
2122          * But it is generally safer to never allow small and huge TLB entries
2123          * for the same virtual address to be loaded simultaneously. So instead
2124          * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2125          * current pmd notpresent (atomically because here the pmd_trans_huge
2126          * must remain set at all times on the pmd until the split is complete
2127          * for this pmd), then we flush the SMP TLB and finally we write the
2128          * non-huge version of the pmd entry with pmd_populate.
2129          */
2130         old_pmd = pmdp_invalidate(vma, haddr, pmd);
2131
2132 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2133         pmd_migration = is_pmd_migration_entry(old_pmd);
2134         if (pmd_migration) {
2135                 swp_entry_t entry;
2136
2137                 entry = pmd_to_swp_entry(old_pmd);
2138                 page = pfn_to_page(swp_offset(entry));
2139         } else
2140 #endif
2141                 page = pmd_page(old_pmd);
2142         VM_BUG_ON_PAGE(!page_count(page), page);
2143         page_ref_add(page, HPAGE_PMD_NR - 1);
2144         if (pmd_dirty(old_pmd))
2145                 SetPageDirty(page);
2146         write = pmd_write(old_pmd);
2147         young = pmd_young(old_pmd);
2148         soft_dirty = pmd_soft_dirty(old_pmd);
2149
2150         /*
2151          * Withdraw the table only after we mark the pmd entry invalid.
2152          * This's critical for some architectures (Power).
2153          */
2154         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2155         pmd_populate(mm, &_pmd, pgtable);
2156
2157         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2158                 pte_t entry, *pte;
2159                 /*
2160                  * Note that NUMA hinting access restrictions are not
2161                  * transferred to avoid any possibility of altering
2162                  * permissions across VMAs.
2163                  */
2164                 if (freeze || pmd_migration) {
2165                         swp_entry_t swp_entry;
2166                         swp_entry = make_migration_entry(page + i, write);
2167                         entry = swp_entry_to_pte(swp_entry);
2168                         if (soft_dirty)
2169                                 entry = pte_swp_mksoft_dirty(entry);
2170                 } else {
2171                         entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2172                         entry = maybe_mkwrite(entry, vma);
2173                         if (!write)
2174                                 entry = pte_wrprotect(entry);
2175                         if (!young)
2176                                 entry = pte_mkold(entry);
2177                         if (soft_dirty)
2178                                 entry = pte_mksoft_dirty(entry);
2179                 }
2180                 pte = pte_offset_map(&_pmd, addr);
2181                 BUG_ON(!pte_none(*pte));
2182                 set_pte_at(mm, addr, pte, entry);
2183                 atomic_inc(&page[i]._mapcount);
2184                 pte_unmap(pte);
2185         }
2186
2187         /*
2188          * Set PG_double_map before dropping compound_mapcount to avoid
2189          * false-negative page_mapped().
2190          */
2191         if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2192                 for (i = 0; i < HPAGE_PMD_NR; i++)
2193                         atomic_inc(&page[i]._mapcount);
2194         }
2195
2196         if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2197                 /* Last compound_mapcount is gone. */
2198                 __dec_node_page_state(page, NR_ANON_THPS);
2199                 if (TestClearPageDoubleMap(page)) {
2200                         /* No need in mapcount reference anymore */
2201                         for (i = 0; i < HPAGE_PMD_NR; i++)
2202                                 atomic_dec(&page[i]._mapcount);
2203                 }
2204         }
2205
2206         smp_wmb(); /* make pte visible before pmd */
2207         pmd_populate(mm, pmd, pgtable);
2208
2209         if (freeze) {
2210                 for (i = 0; i < HPAGE_PMD_NR; i++) {
2211                         page_remove_rmap(page + i, false);
2212                         put_page(page + i);
2213                 }
2214         }
2215 }
2216
2217 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2218                 unsigned long address, bool freeze, struct page *page)
2219 {
2220         spinlock_t *ptl;
2221         struct mm_struct *mm = vma->vm_mm;
2222         unsigned long haddr = address & HPAGE_PMD_MASK;
2223
2224         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2225         ptl = pmd_lock(mm, pmd);
2226
2227         /*
2228          * If caller asks to setup a migration entries, we need a page to check
2229          * pmd against. Otherwise we can end up replacing wrong page.
2230          */
2231         VM_BUG_ON(freeze && !page);
2232         if (page && page != pmd_page(*pmd))
2233                 goto out;
2234
2235         if (pmd_trans_huge(*pmd)) {
2236                 page = pmd_page(*pmd);
2237                 if (PageMlocked(page))
2238                         clear_page_mlock(page);
2239         } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2240                 goto out;
2241         __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2242 out:
2243         spin_unlock(ptl);
2244         /*
2245          * No need to double call mmu_notifier->invalidate_range() callback.
2246          * They are 3 cases to consider inside __split_huge_pmd_locked():
2247          *  1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2248          *  2) __split_huge_zero_page_pmd() read only zero page and any write
2249          *    fault will trigger a flush_notify before pointing to a new page
2250          *    (it is fine if the secondary mmu keeps pointing to the old zero
2251          *    page in the meantime)
2252          *  3) Split a huge pmd into pte pointing to the same page. No need
2253          *     to invalidate secondary tlb entry they are all still valid.
2254          *     any further changes to individual pte will notify. So no need
2255          *     to call mmu_notifier->invalidate_range()
2256          */
2257         mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2258                                                HPAGE_PMD_SIZE);
2259 }
2260
2261 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2262                 bool freeze, struct page *page)
2263 {
2264         pgd_t *pgd;
2265         p4d_t *p4d;
2266         pud_t *pud;
2267         pmd_t *pmd;
2268
2269         pgd = pgd_offset(vma->vm_mm, address);
2270         if (!pgd_present(*pgd))
2271                 return;
2272
2273         p4d = p4d_offset(pgd, address);
2274         if (!p4d_present(*p4d))
2275                 return;
2276
2277         pud = pud_offset(p4d, address);
2278         if (!pud_present(*pud))
2279                 return;
2280
2281         pmd = pmd_offset(pud, address);
2282
2283         __split_huge_pmd(vma, pmd, address, freeze, page);
2284 }
2285
2286 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2287                              unsigned long start,
2288                              unsigned long end,
2289                              long adjust_next)
2290 {
2291         /*
2292          * If the new start address isn't hpage aligned and it could
2293          * previously contain an hugepage: check if we need to split
2294          * an huge pmd.
2295          */
2296         if (start & ~HPAGE_PMD_MASK &&
2297             (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2298             (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2299                 split_huge_pmd_address(vma, start, false, NULL);
2300
2301         /*
2302          * If the new end address isn't hpage aligned and it could
2303          * previously contain an hugepage: check if we need to split
2304          * an huge pmd.
2305          */
2306         if (end & ~HPAGE_PMD_MASK &&
2307             (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2308             (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2309                 split_huge_pmd_address(vma, end, false, NULL);
2310
2311         /*
2312          * If we're also updating the vma->vm_next->vm_start, if the new
2313          * vm_next->vm_start isn't page aligned and it could previously
2314          * contain an hugepage: check if we need to split an huge pmd.
2315          */
2316         if (adjust_next > 0) {
2317                 struct vm_area_struct *next = vma->vm_next;
2318                 unsigned long nstart = next->vm_start;
2319                 nstart += adjust_next << PAGE_SHIFT;
2320                 if (nstart & ~HPAGE_PMD_MASK &&
2321                     (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2322                     (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2323                         split_huge_pmd_address(next, nstart, false, NULL);
2324         }
2325 }
2326
2327 static void freeze_page(struct page *page)
2328 {
2329         enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2330                 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2331         bool unmap_success;
2332
2333         VM_BUG_ON_PAGE(!PageHead(page), page);
2334
2335         if (PageAnon(page))
2336                 ttu_flags |= TTU_SPLIT_FREEZE;
2337
2338         unmap_success = try_to_unmap(page, ttu_flags);
2339         VM_BUG_ON_PAGE(!unmap_success, page);
2340 }
2341
2342 static void unfreeze_page(struct page *page)
2343 {
2344         int i;
2345         if (PageTransHuge(page)) {
2346                 remove_migration_ptes(page, page, true);
2347         } else {
2348                 for (i = 0; i < HPAGE_PMD_NR; i++)
2349                         remove_migration_ptes(page + i, page + i, true);
2350         }
2351 }
2352
2353 static void __split_huge_page_tail(struct page *head, int tail,
2354                 struct lruvec *lruvec, struct list_head *list)
2355 {
2356         struct page *page_tail = head + tail;
2357
2358         VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2359
2360         /*
2361          * Clone page flags before unfreezing refcount.
2362          *
2363          * After successful get_page_unless_zero() might follow flags change,
2364          * for exmaple lock_page() which set PG_waiters.
2365          */
2366         page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2367         page_tail->flags |= (head->flags &
2368                         ((1L << PG_referenced) |
2369                          (1L << PG_swapbacked) |
2370                          (1L << PG_swapcache) |
2371                          (1L << PG_mlocked) |
2372                          (1L << PG_uptodate) |
2373                          (1L << PG_active) |
2374                          (1L << PG_locked) |
2375                          (1L << PG_unevictable) |
2376                          (1L << PG_dirty)));
2377
2378         /* Page flags must be visible before we make the page non-compound. */
2379         smp_wmb();
2380
2381         /*
2382          * Clear PageTail before unfreezing page refcount.
2383          *
2384          * After successful get_page_unless_zero() might follow put_page()
2385          * which needs correct compound_head().
2386          */
2387         clear_compound_head(page_tail);
2388
2389         /* Finally unfreeze refcount. Additional reference from page cache. */
2390         page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2391                                           PageSwapCache(head)));
2392
2393         if (page_is_young(head))
2394                 set_page_young(page_tail);
2395         if (page_is_idle(head))
2396                 set_page_idle(page_tail);
2397
2398         /* ->mapping in first tail page is compound_mapcount */
2399         VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2400                         page_tail);
2401         page_tail->mapping = head->mapping;
2402
2403         page_tail->index = head->index + tail;
2404         page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2405         lru_add_page_tail(head, page_tail, lruvec, list);
2406 }
2407
2408 static void __split_huge_page(struct page *page, struct list_head *list,
2409                 unsigned long flags)
2410 {
2411         struct page *head = compound_head(page);
2412         struct zone *zone = page_zone(head);
2413         struct lruvec *lruvec;
2414         pgoff_t end = -1;
2415         int i;
2416
2417         lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2418
2419         /* complete memcg works before add pages to LRU */
2420         mem_cgroup_split_huge_fixup(head);
2421
2422         if (!PageAnon(page))
2423                 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2424
2425         for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2426                 __split_huge_page_tail(head, i, lruvec, list);
2427                 /* Some pages can be beyond i_size: drop them from page cache */
2428                 if (head[i].index >= end) {
2429                         __ClearPageDirty(head + i);
2430                         __delete_from_page_cache(head + i, NULL);
2431                         if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2432                                 shmem_uncharge(head->mapping->host, 1);
2433                         put_page(head + i);
2434                 }
2435         }
2436
2437         ClearPageCompound(head);
2438         /* See comment in __split_huge_page_tail() */
2439         if (PageAnon(head)) {
2440                 /* Additional pin to radix tree of swap cache */
2441                 if (PageSwapCache(head))
2442                         page_ref_add(head, 2);
2443                 else
2444                         page_ref_inc(head);
2445         } else {
2446                 /* Additional pin to radix tree */
2447                 page_ref_add(head, 2);
2448                 spin_unlock(&head->mapping->tree_lock);
2449         }
2450
2451         spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2452
2453         unfreeze_page(head);
2454
2455         for (i = 0; i < HPAGE_PMD_NR; i++) {
2456                 struct page *subpage = head + i;
2457                 if (subpage == page)
2458                         continue;
2459                 unlock_page(subpage);
2460
2461                 /*
2462                  * Subpages may be freed if there wasn't any mapping
2463                  * like if add_to_swap() is running on a lru page that
2464                  * had its mapping zapped. And freeing these pages
2465                  * requires taking the lru_lock so we do the put_page
2466                  * of the tail pages after the split is complete.
2467                  */
2468                 put_page(subpage);
2469         }
2470 }
2471
2472 int total_mapcount(struct page *page)
2473 {
2474         int i, compound, ret;
2475
2476         VM_BUG_ON_PAGE(PageTail(page), page);
2477
2478         if (likely(!PageCompound(page)))
2479                 return atomic_read(&page->_mapcount) + 1;
2480
2481         compound = compound_mapcount(page);
2482         if (PageHuge(page))
2483                 return compound;
2484         ret = compound;
2485         for (i = 0; i < HPAGE_PMD_NR; i++)
2486                 ret += atomic_read(&page[i]._mapcount) + 1;
2487         /* File pages has compound_mapcount included in _mapcount */
2488         if (!PageAnon(page))
2489                 return ret - compound * HPAGE_PMD_NR;
2490         if (PageDoubleMap(page))
2491                 ret -= HPAGE_PMD_NR;
2492         return ret;
2493 }
2494
2495 /*
2496  * This calculates accurately how many mappings a transparent hugepage
2497  * has (unlike page_mapcount() which isn't fully accurate). This full
2498  * accuracy is primarily needed to know if copy-on-write faults can
2499  * reuse the page and change the mapping to read-write instead of
2500  * copying them. At the same time this returns the total_mapcount too.
2501  *
2502  * The function returns the highest mapcount any one of the subpages
2503  * has. If the return value is one, even if different processes are
2504  * mapping different subpages of the transparent hugepage, they can
2505  * all reuse it, because each process is reusing a different subpage.
2506  *
2507  * The total_mapcount is instead counting all virtual mappings of the
2508  * subpages. If the total_mapcount is equal to "one", it tells the
2509  * caller all mappings belong to the same "mm" and in turn the
2510  * anon_vma of the transparent hugepage can become the vma->anon_vma
2511  * local one as no other process may be mapping any of the subpages.
2512  *
2513  * It would be more accurate to replace page_mapcount() with
2514  * page_trans_huge_mapcount(), however we only use
2515  * page_trans_huge_mapcount() in the copy-on-write faults where we
2516  * need full accuracy to avoid breaking page pinning, because
2517  * page_trans_huge_mapcount() is slower than page_mapcount().
2518  */
2519 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2520 {
2521         int i, ret, _total_mapcount, mapcount;
2522
2523         /* hugetlbfs shouldn't call it */
2524         VM_BUG_ON_PAGE(PageHuge(page), page);
2525
2526         if (likely(!PageTransCompound(page))) {
2527                 mapcount = atomic_read(&page->_mapcount) + 1;
2528                 if (total_mapcount)
2529                         *total_mapcount = mapcount;
2530                 return mapcount;
2531         }
2532
2533         page = compound_head(page);
2534
2535         _total_mapcount = ret = 0;
2536         for (i = 0; i < HPAGE_PMD_NR; i++) {
2537                 mapcount = atomic_read(&page[i]._mapcount) + 1;
2538                 ret = max(ret, mapcount);
2539                 _total_mapcount += mapcount;
2540         }
2541         if (PageDoubleMap(page)) {
2542                 ret -= 1;
2543                 _total_mapcount -= HPAGE_PMD_NR;
2544         }
2545         mapcount = compound_mapcount(page);
2546         ret += mapcount;
2547         _total_mapcount += mapcount;
2548         if (total_mapcount)
2549                 *total_mapcount = _total_mapcount;
2550         return ret;
2551 }
2552
2553 /* Racy check whether the huge page can be split */
2554 bool can_split_huge_page(struct page *page, int *pextra_pins)
2555 {
2556         int extra_pins;
2557
2558         /* Additional pins from radix tree */
2559         if (PageAnon(page))
2560                 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2561         else
2562                 extra_pins = HPAGE_PMD_NR;
2563         if (pextra_pins)
2564                 *pextra_pins = extra_pins;
2565         return total_mapcount(page) == page_count(page) - extra_pins - 1;
2566 }
2567
2568 /*
2569  * This function splits huge page into normal pages. @page can point to any
2570  * subpage of huge page to split. Split doesn't change the position of @page.
2571  *
2572  * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2573  * The huge page must be locked.
2574  *
2575  * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2576  *
2577  * Both head page and tail pages will inherit mapping, flags, and so on from
2578  * the hugepage.
2579  *
2580  * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2581  * they are not mapped.
2582  *
2583  * Returns 0 if the hugepage is split successfully.
2584  * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2585  * us.
2586  */
2587 int split_huge_page_to_list(struct page *page, struct list_head *list)
2588 {
2589         struct page *head = compound_head(page);
2590         struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2591         struct anon_vma *anon_vma = NULL;
2592         struct address_space *mapping = NULL;
2593         int count, mapcount, extra_pins, ret;
2594         bool mlocked;
2595         unsigned long flags;
2596
2597         VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2598         VM_BUG_ON_PAGE(!PageLocked(page), page);
2599         VM_BUG_ON_PAGE(!PageCompound(page), page);
2600
2601         if (PageWriteback(page))
2602                 return -EBUSY;
2603
2604         if (PageAnon(head)) {
2605                 /*
2606                  * The caller does not necessarily hold an mmap_sem that would
2607                  * prevent the anon_vma disappearing so we first we take a
2608                  * reference to it and then lock the anon_vma for write. This
2609                  * is similar to page_lock_anon_vma_read except the write lock
2610                  * is taken to serialise against parallel split or collapse
2611                  * operations.
2612                  */
2613                 anon_vma = page_get_anon_vma(head);
2614                 if (!anon_vma) {
2615                         ret = -EBUSY;
2616                         goto out;
2617                 }
2618                 mapping = NULL;
2619                 anon_vma_lock_write(anon_vma);
2620         } else {
2621                 mapping = head->mapping;
2622
2623                 /* Truncated ? */
2624                 if (!mapping) {
2625                         ret = -EBUSY;
2626                         goto out;
2627                 }
2628
2629                 anon_vma = NULL;
2630                 i_mmap_lock_read(mapping);
2631         }
2632
2633         /*
2634          * Racy check if we can split the page, before freeze_page() will
2635          * split PMDs
2636          */
2637         if (!can_split_huge_page(head, &extra_pins)) {
2638                 ret = -EBUSY;
2639                 goto out_unlock;
2640         }
2641
2642         mlocked = PageMlocked(page);
2643         freeze_page(head);
2644         VM_BUG_ON_PAGE(compound_mapcount(head), head);
2645
2646         /* Make sure the page is not on per-CPU pagevec as it takes pin */
2647         if (mlocked)
2648                 lru_add_drain();
2649
2650         /* prevent PageLRU to go away from under us, and freeze lru stats */
2651         spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2652
2653         if (mapping) {
2654                 void **pslot;
2655
2656                 spin_lock(&mapping->tree_lock);
2657                 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2658                                 page_index(head));
2659                 /*
2660                  * Check if the head page is present in radix tree.
2661                  * We assume all tail are present too, if head is there.
2662                  */
2663                 if (radix_tree_deref_slot_protected(pslot,
2664                                         &mapping->tree_lock) != head)
2665                         goto fail;
2666         }
2667
2668         /* Prevent deferred_split_scan() touching ->_refcount */
2669         spin_lock(&pgdata->split_queue_lock);
2670         count = page_count(head);
2671         mapcount = total_mapcount(head);
2672         if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2673                 if (!list_empty(page_deferred_list(head))) {
2674                         pgdata->split_queue_len--;
2675                         list_del(page_deferred_list(head));
2676                 }
2677                 if (mapping)
2678                         __dec_node_page_state(page, NR_SHMEM_THPS);
2679                 spin_unlock(&pgdata->split_queue_lock);
2680                 __split_huge_page(page, list, flags);
2681                 if (PageSwapCache(head)) {
2682                         swp_entry_t entry = { .val = page_private(head) };
2683
2684                         ret = split_swap_cluster(entry);
2685                 } else
2686                         ret = 0;
2687         } else {
2688                 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2689                         pr_alert("total_mapcount: %u, page_count(): %u\n",
2690                                         mapcount, count);
2691                         if (PageTail(page))
2692                                 dump_page(head, NULL);
2693                         dump_page(page, "total_mapcount(head) > 0");
2694                         BUG();
2695                 }
2696                 spin_unlock(&pgdata->split_queue_lock);
2697 fail:           if (mapping)
2698                         spin_unlock(&mapping->tree_lock);
2699                 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2700                 unfreeze_page(head);
2701                 ret = -EBUSY;
2702         }
2703
2704 out_unlock:
2705         if (anon_vma) {
2706                 anon_vma_unlock_write(anon_vma);
2707                 put_anon_vma(anon_vma);
2708         }
2709         if (mapping)
2710                 i_mmap_unlock_read(mapping);
2711 out:
2712         count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2713         return ret;
2714 }
2715
2716 void free_transhuge_page(struct page *page)
2717 {
2718         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2719         unsigned long flags;
2720
2721         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2722         if (!list_empty(page_deferred_list(page))) {
2723                 pgdata->split_queue_len--;
2724                 list_del(page_deferred_list(page));
2725         }
2726         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2727         free_compound_page(page);
2728 }
2729
2730 void deferred_split_huge_page(struct page *page)
2731 {
2732         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2733         unsigned long flags;
2734
2735         VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2736
2737         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2738         if (list_empty(page_deferred_list(page))) {
2739                 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2740                 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2741                 pgdata->split_queue_len++;
2742         }
2743         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2744 }
2745
2746 static unsigned long deferred_split_count(struct shrinker *shrink,
2747                 struct shrink_control *sc)
2748 {
2749         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2750         return READ_ONCE(pgdata->split_queue_len);
2751 }
2752
2753 static unsigned long deferred_split_scan(struct shrinker *shrink,
2754                 struct shrink_control *sc)
2755 {
2756         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2757         unsigned long flags;
2758         LIST_HEAD(list), *pos, *next;
2759         struct page *page;
2760         int split = 0;
2761
2762         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2763         /* Take pin on all head pages to avoid freeing them under us */
2764         list_for_each_safe(pos, next, &pgdata->split_queue) {
2765                 page = list_entry((void *)pos, struct page, mapping);
2766                 page = compound_head(page);
2767                 if (get_page_unless_zero(page)) {
2768                         list_move(page_deferred_list(page), &list);
2769                 } else {
2770                         /* We lost race with put_compound_page() */
2771                         list_del_init(page_deferred_list(page));
2772                         pgdata->split_queue_len--;
2773                 }
2774                 if (!--sc->nr_to_scan)
2775                         break;
2776         }
2777         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2778
2779         list_for_each_safe(pos, next, &list) {
2780                 page = list_entry((void *)pos, struct page, mapping);
2781                 if (!trylock_page(page))
2782                         goto next;
2783                 /* split_huge_page() removes page from list on success */
2784                 if (!split_huge_page(page))
2785                         split++;
2786                 unlock_page(page);
2787 next:
2788                 put_page(page);
2789         }
2790
2791         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2792         list_splice_tail(&list, &pgdata->split_queue);
2793         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2794
2795         /*
2796          * Stop shrinker if we didn't split any page, but the queue is empty.
2797          * This can happen if pages were freed under us.
2798          */
2799         if (!split && list_empty(&pgdata->split_queue))
2800                 return SHRINK_STOP;
2801         return split;
2802 }
2803
2804 static struct shrinker deferred_split_shrinker = {
2805         .count_objects = deferred_split_count,
2806         .scan_objects = deferred_split_scan,
2807         .seeks = DEFAULT_SEEKS,
2808         .flags = SHRINKER_NUMA_AWARE,
2809 };
2810
2811 #ifdef CONFIG_DEBUG_FS
2812 static int split_huge_pages_set(void *data, u64 val)
2813 {
2814         struct zone *zone;
2815         struct page *page;
2816         unsigned long pfn, max_zone_pfn;
2817         unsigned long total = 0, split = 0;
2818
2819         if (val != 1)
2820                 return -EINVAL;
2821
2822         for_each_populated_zone(zone) {
2823                 max_zone_pfn = zone_end_pfn(zone);
2824                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2825                         if (!pfn_valid(pfn))
2826                                 continue;
2827
2828                         page = pfn_to_page(pfn);
2829                         if (!get_page_unless_zero(page))
2830                                 continue;
2831
2832                         if (zone != page_zone(page))
2833                                 goto next;
2834
2835                         if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2836                                 goto next;
2837
2838                         total++;
2839                         lock_page(page);
2840                         if (!split_huge_page(page))
2841                                 split++;
2842                         unlock_page(page);
2843 next:
2844                         put_page(page);
2845                 }
2846         }
2847
2848         pr_info("%lu of %lu THP split\n", split, total);
2849
2850         return 0;
2851 }
2852 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2853                 "%llu\n");
2854
2855 static int __init split_huge_pages_debugfs(void)
2856 {
2857         void *ret;
2858
2859         ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2860                         &split_huge_pages_fops);
2861         if (!ret)
2862                 pr_warn("Failed to create split_huge_pages in debugfs");
2863         return 0;
2864 }
2865 late_initcall(split_huge_pages_debugfs);
2866 #endif
2867
2868 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2869 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2870                 struct page *page)
2871 {
2872         struct vm_area_struct *vma = pvmw->vma;
2873         struct mm_struct *mm = vma->vm_mm;
2874         unsigned long address = pvmw->address;
2875         pmd_t pmdval;
2876         swp_entry_t entry;
2877         pmd_t pmdswp;
2878
2879         if (!(pvmw->pmd && !pvmw->pte))
2880                 return;
2881
2882         mmu_notifier_invalidate_range_start(mm, address,
2883                         address + HPAGE_PMD_SIZE);
2884
2885         flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2886         pmdval = *pvmw->pmd;
2887         pmdp_invalidate(vma, address, pvmw->pmd);
2888         if (pmd_dirty(pmdval))
2889                 set_page_dirty(page);
2890         entry = make_migration_entry(page, pmd_write(pmdval));
2891         pmdswp = swp_entry_to_pmd(entry);
2892         if (pmd_soft_dirty(pmdval))
2893                 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2894         set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2895         page_remove_rmap(page, true);
2896         put_page(page);
2897
2898         mmu_notifier_invalidate_range_end(mm, address,
2899                         address + HPAGE_PMD_SIZE);
2900 }
2901
2902 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2903 {
2904         struct vm_area_struct *vma = pvmw->vma;
2905         struct mm_struct *mm = vma->vm_mm;
2906         unsigned long address = pvmw->address;
2907         unsigned long mmun_start = address & HPAGE_PMD_MASK;
2908         pmd_t pmde;
2909         swp_entry_t entry;
2910
2911         if (!(pvmw->pmd && !pvmw->pte))
2912                 return;
2913
2914         entry = pmd_to_swp_entry(*pvmw->pmd);
2915         get_page(new);
2916         pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2917         if (pmd_swp_soft_dirty(*pvmw->pmd))
2918                 pmde = pmd_mksoft_dirty(pmde);
2919         if (is_write_migration_entry(entry))
2920                 pmde = maybe_pmd_mkwrite(pmde, vma);
2921
2922         flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2923         page_add_anon_rmap(new, vma, mmun_start, true);
2924         set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2925         if (vma->vm_flags & VM_LOCKED)
2926                 mlock_vma_page(new);
2927         update_mmu_cache_pmd(vma, address, pvmw->pmd);
2928 }
2929 #endif