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 that avoid
  43  * to risk increase the memory footprint of applications without a guaranteed
  44  * benefit. When transparent hugepage support is enabled, is for all mappings,
  45  * 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, &memcg, true)) {
 559                 put_page(page);
 560                 count_vm_event(THP_FAULT_FALLBACK);
 561                 return VM_FAULT_FALLBACK;
 562         }
 563
 564         pgtable = pte_alloc_one(vma->vm_mm, haddr);
 565         if (unlikely(!pgtable)) {
 566                 ret = VM_FAULT_OOM;
 567                 goto release;
 568         }
 569
 570         clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
 571         /*
 572          * The memory barrier inside __SetPageUptodate makes sure that
 573          * clear_huge_page writes become visible before the set_pmd_at()
 574          * write.
 575          */
 576         __SetPageUptodate(page);
 577
 578         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 579         if (unlikely(!pmd_none(*vmf->pmd))) {
 580                 goto unlock_release;
 581         } else {
 582                 pmd_t entry;
 583
 584                 ret = check_stable_address_space(vma->vm_mm);
 585                 if (ret)
 586                         goto unlock_release;
 587
 588                 /* Deliver the page fault to userland */
 589                 if (userfaultfd_missing(vma)) {
 590                         int ret;
 591
 592                         spin_unlock(vmf->ptl);
 593                         mem_cgroup_cancel_charge(page, memcg, true);
 594                         put_page(page);
 595                         pte_free(vma->vm_mm, pgtable);
 596                         ret = handle_userfault(vmf, VM_UFFD_MISSING);
 597                         VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 598                         return ret;
 599                 }
 600
 601                 entry = mk_huge_pmd(page, vma->vm_page_prot);
 602                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 603                 page_add_new_anon_rmap(page, vma, haddr, true);
 604                 mem_cgroup_commit_charge(page, memcg, false, true);
 605                 lru_cache_add_active_or_unevictable(page, vma);
 606                 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
 607                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
 608                 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 609                 atomic_long_inc(&vma->vm_mm->nr_ptes);
 610                 spin_unlock(vmf->ptl);
 611                 count_vm_event(THP_FAULT_ALLOC);
 612         }
 613
 614         return 0;
 615 unlock_release:
 616         spin_unlock(vmf->ptl);
 617 release:
 618         if (pgtable)
 619                 pte_free(vma->vm_mm, pgtable);
 620         mem_cgroup_cancel_charge(page, memcg, true);
 621         put_page(page);
 622         return ret;
 623
 624 }
 625
 626 /*
 627  * always: directly stall for all thp allocations
 628  * defer: wake kswapd and fail if not immediately available
 629  * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
 630  *                fail if not immediately available
 631  * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
 632  *          available
 633  * never: never stall for any thp allocation
 634  */
 635 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
 636 {
 637         const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
 638
 639         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 640                 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
 641         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 642                 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
 643         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 644                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 645                                                              __GFP_KSWAPD_RECLAIM);
 646         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 647                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 648                                                              0);
 649         return GFP_TRANSHUGE_LIGHT;
 650 }
 651
 652 /* Caller must hold page table lock. */
 653 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 654                 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
 655                 struct page *zero_page)
 656 {
 657         pmd_t entry;
 658         if (!pmd_none(*pmd))
 659                 return false;
 660         entry = mk_pmd(zero_page, vma->vm_page_prot);
 661         entry = pmd_mkhuge(entry);
 662         if (pgtable)
 663                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 664         set_pmd_at(mm, haddr, pmd, entry);
 665         atomic_long_inc(&mm->nr_ptes);
 666         return true;
 667 }
 668
 669 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 670 {
 671         struct vm_area_struct *vma = vmf->vma;
 672         gfp_t gfp;
 673         struct page *page;
 674         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 675
 676         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
 677                 return VM_FAULT_FALLBACK;
 678         if (unlikely(anon_vma_prepare(vma)))
 679                 return VM_FAULT_OOM;
 680         if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
 681                 return VM_FAULT_OOM;
 682         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
 683                         !mm_forbids_zeropage(vma->vm_mm) &&
 684                         transparent_hugepage_use_zero_page()) {
 685                 pgtable_t pgtable;
 686                 struct page *zero_page;
 687                 bool set;
 688                 int ret;
 689                 pgtable = pte_alloc_one(vma->vm_mm, haddr);
 690                 if (unlikely(!pgtable))
 691                         return VM_FAULT_OOM;
 692                 zero_page = mm_get_huge_zero_page(vma->vm_mm);
 693                 if (unlikely(!zero_page)) {
 694                         pte_free(vma->vm_mm, pgtable);
 695                         count_vm_event(THP_FAULT_FALLBACK);
 696                         return VM_FAULT_FALLBACK;
 697                 }
 698                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 699                 ret = 0;
 700                 set = false;
 701                 if (pmd_none(*vmf->pmd)) {
 702                         ret = check_stable_address_space(vma->vm_mm);
 703                         if (ret) {
 704                                 spin_unlock(vmf->ptl);
 705                         } else if (userfaultfd_missing(vma)) {
 706                                 spin_unlock(vmf->ptl);
 707                                 ret = handle_userfault(vmf, VM_UFFD_MISSING);
 708                                 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 709                         } else {
 710                                 set_huge_zero_page(pgtable, vma->vm_mm, vma,
 711                                                    haddr, vmf->pmd, zero_page);
 712                                 spin_unlock(vmf->ptl);
 713                                 set = true;
 714                         }
 715                 } else
 716                         spin_unlock(vmf->ptl);
 717                 if (!set)
 718                         pte_free(vma->vm_mm, pgtable);
 719                 return ret;
 720         }
 721         gfp = alloc_hugepage_direct_gfpmask(vma);
 722         page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
 723         if (unlikely(!page)) {
 724                 count_vm_event(THP_FAULT_FALLBACK);
 725                 return VM_FAULT_FALLBACK;
 726         }
 727         prep_transhuge_page(page);
 728         return __do_huge_pmd_anonymous_page(vmf, page, gfp);
 729 }
 730
 731 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 732                 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
 733                 pgtable_t pgtable)
 734 {
 735         struct mm_struct *mm = vma->vm_mm;
 736         pmd_t entry;
 737         spinlock_t *ptl;
 738
 739         ptl = pmd_lock(mm, pmd);
 740         entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
 741         if (pfn_t_devmap(pfn))
 742                 entry = pmd_mkdevmap(entry);
 743         if (write) {
 744                 entry = pmd_mkyoung(pmd_mkdirty(entry));
 745                 entry = maybe_pmd_mkwrite(entry, vma);
 746         }
 747
 748         if (pgtable) {
 749                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 750                 atomic_long_inc(&mm->nr_ptes);
 751         }
 752
 753         set_pmd_at(mm, addr, pmd, entry);
 754         update_mmu_cache_pmd(vma, addr, pmd);
 755         spin_unlock(ptl);
 756 }
 757
 758 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 759                         pmd_t *pmd, pfn_t pfn, bool write)
 760 {
 761         pgprot_t pgprot = vma->vm_page_prot;
 762         pgtable_t pgtable = NULL;
 763         /*
 764          * If we had pmd_special, we could avoid all these restrictions,
 765          * but we need to be consistent with PTEs and architectures that
 766          * can't support a 'special' bit.
 767          */
 768         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 769         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 770                                                 (VM_PFNMAP|VM_MIXEDMAP));
 771         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 772         BUG_ON(!pfn_t_devmap(pfn));
 773
 774         if (addr < vma->vm_start || addr >= vma->vm_end)
 775                 return VM_FAULT_SIGBUS;
 776
 777         if (arch_needs_pgtable_deposit()) {
 778                 pgtable = pte_alloc_one(vma->vm_mm, addr);
 779                 if (!pgtable)
 780                         return VM_FAULT_OOM;
 781         }
 782
 783         track_pfn_insert(vma, &pgprot, pfn);
 784
 785         insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
 786         return VM_FAULT_NOPAGE;
 787 }
 788 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
 789
 790 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 791 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
 792 {
 793         if (likely(vma->vm_flags & VM_WRITE))
 794                 pud = pud_mkwrite(pud);
 795         return pud;
 796 }
 797
 798 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 799                 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
 800 {
 801         struct mm_struct *mm = vma->vm_mm;
 802         pud_t entry;
 803         spinlock_t *ptl;
 804
 805         ptl = pud_lock(mm, pud);
 806         entry = pud_mkhuge(pfn_t_pud(pfn, prot));
 807         if (pfn_t_devmap(pfn))
 808                 entry = pud_mkdevmap(entry);
 809         if (write) {
 810                 entry = pud_mkyoung(pud_mkdirty(entry));
 811                 entry = maybe_pud_mkwrite(entry, vma);
 812         }
 813         set_pud_at(mm, addr, pud, entry);
 814         update_mmu_cache_pud(vma, addr, pud);
 815         spin_unlock(ptl);
 816 }
 817
 818 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 819                         pud_t *pud, pfn_t pfn, bool write)
 820 {
 821         pgprot_t pgprot = vma->vm_page_prot;
 822         /*
 823          * If we had pud_special, we could avoid all these restrictions,
 824          * but we need to be consistent with PTEs and architectures that
 825          * can't support a 'special' bit.
 826          */
 827         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 828         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 829                                                 (VM_PFNMAP|VM_MIXEDMAP));
 830         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 831         BUG_ON(!pfn_t_devmap(pfn));
 832
 833         if (addr < vma->vm_start || addr >= vma->vm_end)
 834                 return VM_FAULT_SIGBUS;
 835
 836         track_pfn_insert(vma, &pgprot, pfn);
 837
 838         insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
 839         return VM_FAULT_NOPAGE;
 840 }
 841 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
 842 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 843
 844 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 845                 pmd_t *pmd)
 846 {
 847         pmd_t _pmd;
 848
 849         /*
 850          * We should set the dirty bit only for FOLL_WRITE but for now
 851          * the dirty bit in the pmd is meaningless.  And if the dirty
 852          * bit will become meaningful and we'll only set it with
 853          * FOLL_WRITE, an atomic set_bit will be required on the pmd to
 854          * set the young bit, instead of the current set_pmd_at.
 855          */
 856         _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
 857         if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
 858                                 pmd, _pmd,  1))
 859                 update_mmu_cache_pmd(vma, addr, pmd);
 860 }
 861
 862 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 863                 pmd_t *pmd, int flags)
 864 {
 865         unsigned long pfn = pmd_pfn(*pmd);
 866         struct mm_struct *mm = vma->vm_mm;
 867         struct dev_pagemap *pgmap;
 868         struct page *page;
 869
 870         assert_spin_locked(pmd_lockptr(mm, pmd));
 871
 872         /*
 873          * When we COW a devmap PMD entry, we split it into PTEs, so we should
 874          * not be in this function with `flags & FOLL_COW` set.
 875          */
 876         WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
 877
 878         if (flags & FOLL_WRITE && !pmd_write(*pmd))
 879                 return NULL;
 880
 881         if (pmd_present(*pmd) && pmd_devmap(*pmd))
 882                 /* pass */;
 883         else
 884                 return NULL;
 885
 886         if (flags & FOLL_TOUCH)
 887                 touch_pmd(vma, addr, pmd);
 888
 889         /*
 890          * device mapped pages can only be returned if the
 891          * caller will manage the page reference count.
 892          */
 893         if (!(flags & FOLL_GET))
 894                 return ERR_PTR(-EEXIST);
 895
 896         pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
 897         pgmap = get_dev_pagemap(pfn, NULL);
 898         if (!pgmap)
 899                 return ERR_PTR(-EFAULT);
 900         page = pfn_to_page(pfn);
 901         get_page(page);
 902         put_dev_pagemap(pgmap);
 903
 904         return page;
 905 }
 906
 907 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 908                   pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 909                   struct vm_area_struct *vma)
 910 {
 911         spinlock_t *dst_ptl, *src_ptl;
 912         struct page *src_page;
 913         pmd_t pmd;
 914         pgtable_t pgtable = NULL;
 915         int ret = -ENOMEM;
 916
 917         /* Skip if can be re-fill on fault */
 918         if (!vma_is_anonymous(vma))
 919                 return 0;
 920
 921         pgtable = pte_alloc_one(dst_mm, addr);
 922         if (unlikely(!pgtable))
 923                 goto out;
 924
 925         dst_ptl = pmd_lock(dst_mm, dst_pmd);
 926         src_ptl = pmd_lockptr(src_mm, src_pmd);
 927         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 928
 929         ret = -EAGAIN;
 930         pmd = *src_pmd;
 931
 932 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 933         if (unlikely(is_swap_pmd(pmd))) {
 934                 swp_entry_t entry = pmd_to_swp_entry(pmd);
 935
 936                 VM_BUG_ON(!is_pmd_migration_entry(pmd));
 937                 if (is_write_migration_entry(entry)) {
 938                         make_migration_entry_read(&entry);
 939                         pmd = swp_entry_to_pmd(entry);
 940                         if (pmd_swp_soft_dirty(*src_pmd))
 941                                 pmd = pmd_swp_mksoft_dirty(pmd);
 942                         set_pmd_at(src_mm, addr, src_pmd, pmd);
 943                 }
 944                 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 945                 atomic_long_inc(&dst_mm->nr_ptes);
 946                 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 947                 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 948                 ret = 0;
 949                 goto out_unlock;
 950         }
 951 #endif
 952
 953         if (unlikely(!pmd_trans_huge(pmd))) {
 954                 pte_free(dst_mm, pgtable);
 955                 goto out_unlock;
 956         }
 957         /*
 958          * When page table lock is held, the huge zero pmd should not be
 959          * under splitting since we don't split the page itself, only pmd to
 960          * a page table.
 961          */
 962         if (is_huge_zero_pmd(pmd)) {
 963                 struct page *zero_page;
 964                 /*
 965                  * get_huge_zero_page() will never allocate a new page here,
 966                  * since we already have a zero page to copy. It just takes a
 967                  * reference.
 968                  */
 969                 zero_page = mm_get_huge_zero_page(dst_mm);
 970                 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
 971                                 zero_page);
 972                 ret = 0;
 973                 goto out_unlock;
 974         }
 975
 976         src_page = pmd_page(pmd);
 977         VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
 978         get_page(src_page);
 979         page_dup_rmap(src_page, true);
 980         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 981         atomic_long_inc(&dst_mm->nr_ptes);
 982         pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 983
 984         pmdp_set_wrprotect(src_mm, addr, src_pmd);
 985         pmd = pmd_mkold(pmd_wrprotect(pmd));
 986         set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 987
 988         ret = 0;
 989 out_unlock:
 990         spin_unlock(src_ptl);
 991         spin_unlock(dst_ptl);
 992 out:
 993         return ret;
 994 }
 995
 996 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 997 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
 998                 pud_t *pud)
 999 {
1000         pud_t _pud;
1001
1002         /*
1003          * We should set the dirty bit only for FOLL_WRITE but for now
1004          * the dirty bit in the pud is meaningless.  And if the dirty
1005          * bit will become meaningful and we'll only set it with
1006          * FOLL_WRITE, an atomic set_bit will be required on the pud to
1007          * set the young bit, instead of the current set_pud_at.
1008          */
1009         _pud = pud_mkyoung(pud_mkdirty(*pud));
1010         if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1011                                 pud, _pud,  1))
1012                 update_mmu_cache_pud(vma, addr, pud);
1013 }
1014
1015 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1016                 pud_t *pud, int flags)
1017 {
1018         unsigned long pfn = pud_pfn(*pud);
1019         struct mm_struct *mm = vma->vm_mm;
1020         struct dev_pagemap *pgmap;
1021         struct page *page;
1022
1023         assert_spin_locked(pud_lockptr(mm, pud));
1024
1025         if (flags & FOLL_WRITE && !pud_write(*pud))
1026                 return NULL;
1027
1028         if (pud_present(*pud) && pud_devmap(*pud))
1029                 /* pass */;
1030         else
1031                 return NULL;
1032
1033         if (flags & FOLL_TOUCH)
1034                 touch_pud(vma, addr, pud);
1035
1036         /*
1037          * device mapped pages can only be returned if the
1038          * caller will manage the page reference count.
1039          */
1040         if (!(flags & FOLL_GET))
1041                 return ERR_PTR(-EEXIST);
1042
1043         pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1044         pgmap = get_dev_pagemap(pfn, NULL);
1045         if (!pgmap)
1046                 return ERR_PTR(-EFAULT);
1047         page = pfn_to_page(pfn);
1048         get_page(page);
1049         put_dev_pagemap(pgmap);
1050
1051         return page;
1052 }
1053
1054 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1055                   pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1056                   struct vm_area_struct *vma)
1057 {
1058         spinlock_t *dst_ptl, *src_ptl;
1059         pud_t pud;
1060         int ret;
1061
1062         dst_ptl = pud_lock(dst_mm, dst_pud);
1063         src_ptl = pud_lockptr(src_mm, src_pud);
1064         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1065
1066         ret = -EAGAIN;
1067         pud = *src_pud;
1068         if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1069                 goto out_unlock;
1070
1071         /*
1072          * When page table lock is held, the huge zero pud should not be
1073          * under splitting since we don't split the page itself, only pud to
1074          * a page table.
1075          */
1076         if (is_huge_zero_pud(pud)) {
1077                 /* No huge zero pud yet */
1078         }
1079
1080         pudp_set_wrprotect(src_mm, addr, src_pud);
1081         pud = pud_mkold(pud_wrprotect(pud));
1082         set_pud_at(dst_mm, addr, dst_pud, pud);
1083
1084         ret = 0;
1085 out_unlock:
1086         spin_unlock(src_ptl);
1087         spin_unlock(dst_ptl);
1088         return ret;
1089 }
1090
1091 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1092 {
1093         pud_t entry;
1094         unsigned long haddr;
1095         bool write = vmf->flags & FAULT_FLAG_WRITE;
1096
1097         vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1098         if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1099                 goto unlock;
1100
1101         entry = pud_mkyoung(orig_pud);
1102         if (write)
1103                 entry = pud_mkdirty(entry);
1104         haddr = vmf->address & HPAGE_PUD_MASK;
1105         if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1106                 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1107
1108 unlock:
1109         spin_unlock(vmf->ptl);
1110 }
1111 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1112
1113 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1114 {
1115         pmd_t entry;
1116         unsigned long haddr;
1117         bool write = vmf->flags & FAULT_FLAG_WRITE;
1118
1119         vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1120         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1121                 goto unlock;
1122
1123         entry = pmd_mkyoung(orig_pmd);
1124         if (write)
1125                 entry = pmd_mkdirty(entry);
1126         haddr = vmf->address & HPAGE_PMD_MASK;
1127         if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1128                 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1129
1130 unlock:
1131         spin_unlock(vmf->ptl);
1132 }
1133
1134 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1135                 struct page *page)
1136 {
1137         struct vm_area_struct *vma = vmf->vma;
1138         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1139         struct mem_cgroup *memcg;
1140         pgtable_t pgtable;
1141         pmd_t _pmd;
1142         int ret = 0, i;
1143         struct page **pages;
1144         unsigned long mmun_start;       /* For mmu_notifiers */
1145         unsigned long mmun_end;         /* For mmu_notifiers */
1146
1147         pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1148                         GFP_KERNEL);
1149         if (unlikely(!pages)) {
1150                 ret |= VM_FAULT_OOM;
1151                 goto out;
1152         }
1153
1154         for (i = 0; i < HPAGE_PMD_NR; i++) {
1155                 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1156                                                vmf->address, page_to_nid(page));
1157                 if (unlikely(!pages[i] ||
1158                              mem_cgroup_try_charge(pages[i], vma->vm_mm,
1159                                      GFP_KERNEL, &memcg, false))) {
1160                         if (pages[i])
1161                                 put_page(pages[i]);
1162                         while (--i >= 0) {
1163                                 memcg = (void *)page_private(pages[i]);
1164                                 set_page_private(pages[i], 0);
1165                                 mem_cgroup_cancel_charge(pages[i], memcg,
1166                                                 false);
1167                                 put_page(pages[i]);
1168                         }
1169                         kfree(pages);
1170                         ret |= VM_FAULT_OOM;
1171                         goto out;
1172                 }
1173                 set_page_private(pages[i], (unsigned long)memcg);
1174         }
1175
1176         for (i = 0; i < HPAGE_PMD_NR; i++) {
1177                 copy_user_highpage(pages[i], page + i,
1178                                    haddr + PAGE_SIZE * i, vma);
1179                 __SetPageUptodate(pages[i]);
1180                 cond_resched();
1181         }
1182
1183         mmun_start = haddr;
1184         mmun_end   = haddr + HPAGE_PMD_SIZE;
1185         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1186
1187         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1188         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1189                 goto out_free_pages;
1190         VM_BUG_ON_PAGE(!PageHead(page), page);
1191
1192         pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1193         /* leave pmd empty until pte is filled */
1194
1195         pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1196         pmd_populate(vma->vm_mm, &_pmd, pgtable);
1197
1198         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1199                 pte_t entry;
1200                 entry = mk_pte(pages[i], vma->vm_page_prot);
1201                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1202                 memcg = (void *)page_private(pages[i]);
1203                 set_page_private(pages[i], 0);
1204                 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1205                 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1206                 lru_cache_add_active_or_unevictable(pages[i], vma);
1207                 vmf->pte = pte_offset_map(&_pmd, haddr);
1208                 VM_BUG_ON(!pte_none(*vmf->pte));
1209                 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1210                 pte_unmap(vmf->pte);
1211         }
1212         kfree(pages);
1213
1214         smp_wmb(); /* make pte visible before pmd */
1215         pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1216         page_remove_rmap(page, true);
1217         spin_unlock(vmf->ptl);
1218
1219         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1220
1221         ret |= VM_FAULT_WRITE;
1222         put_page(page);
1223
1224 out:
1225         return ret;
1226
1227 out_free_pages:
1228         spin_unlock(vmf->ptl);
1229         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1230         for (i = 0; i < HPAGE_PMD_NR; i++) {
1231                 memcg = (void *)page_private(pages[i]);
1232                 set_page_private(pages[i], 0);
1233                 mem_cgroup_cancel_charge(pages[i], memcg, false);
1234                 put_page(pages[i]);
1235         }
1236         kfree(pages);
1237         goto out;
1238 }
1239
1240 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1241 {
1242         struct vm_area_struct *vma = vmf->vma;
1243         struct page *page = NULL, *new_page;
1244         struct mem_cgroup *memcg;
1245         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1246         unsigned long mmun_start;       /* For mmu_notifiers */
1247         unsigned long mmun_end;         /* For mmu_notifiers */
1248         gfp_t huge_gfp;                 /* for allocation and charge */
1249         int ret = 0;
1250
1251         vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1252         VM_BUG_ON_VMA(!vma->anon_vma, vma);
1253         if (is_huge_zero_pmd(orig_pmd))
1254                 goto alloc;
1255         spin_lock(vmf->ptl);
1256         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1257                 goto out_unlock;
1258
1259         page = pmd_page(orig_pmd);
1260         VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1261         /*
1262          * We can only reuse the page if nobody else maps the huge page or it's
1263          * part.
1264          */
1265         if (!trylock_page(page)) {
1266                 get_page(page);
1267                 spin_unlock(vmf->ptl);
1268                 lock_page(page);
1269                 spin_lock(vmf->ptl);
1270                 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1271                         unlock_page(page);
1272                         put_page(page);
1273                         goto out_unlock;
1274                 }
1275                 put_page(page);
1276         }
1277         if (reuse_swap_page(page, NULL)) {
1278                 pmd_t entry;
1279                 entry = pmd_mkyoung(orig_pmd);
1280                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1281                 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry,  1))
1282                         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1283                 ret |= VM_FAULT_WRITE;
1284                 unlock_page(page);
1285                 goto out_unlock;
1286         }
1287         unlock_page(page);
1288         get_page(page);
1289         spin_unlock(vmf->ptl);
1290 alloc:
1291         if (transparent_hugepage_enabled(vma) &&
1292             !transparent_hugepage_debug_cow()) {
1293                 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1294                 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1295         } else
1296                 new_page = NULL;
1297
1298         if (likely(new_page)) {
1299                 prep_transhuge_page(new_page);
1300         } else {
1301                 if (!page) {
1302                         split_huge_pmd(vma, vmf->pmd, vmf->address);
1303                         ret |= VM_FAULT_FALLBACK;
1304                 } else {
1305                         ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1306                         if (ret & VM_FAULT_OOM) {
1307                                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1308                                 ret |= VM_FAULT_FALLBACK;
1309                         }
1310                         put_page(page);
1311                 }
1312                 count_vm_event(THP_FAULT_FALLBACK);
1313                 goto out;
1314         }
1315
1316         if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1317                                         huge_gfp, &memcg, true))) {
1318                 put_page(new_page);
1319                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1320                 if (page)
1321                         put_page(page);
1322                 ret |= VM_FAULT_FALLBACK;
1323                 count_vm_event(THP_FAULT_FALLBACK);
1324                 goto out;
1325         }
1326
1327         count_vm_event(THP_FAULT_ALLOC);
1328
1329         if (!page)
1330                 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1331         else
1332                 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1333         __SetPageUptodate(new_page);
1334
1335         mmun_start = haddr;
1336         mmun_end   = haddr + HPAGE_PMD_SIZE;
1337         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1338
1339         spin_lock(vmf->ptl);
1340         if (page)
1341                 put_page(page);
1342         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1343                 spin_unlock(vmf->ptl);
1344                 mem_cgroup_cancel_charge(new_page, memcg, true);
1345                 put_page(new_page);
1346                 goto out_mn;
1347         } else {
1348                 pmd_t entry;
1349                 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1350                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1351                 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1352                 page_add_new_anon_rmap(new_page, vma, haddr, true);
1353                 mem_cgroup_commit_charge(new_page, memcg, false, true);
1354                 lru_cache_add_active_or_unevictable(new_page, vma);
1355                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1356                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1357                 if (!page) {
1358                         add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1359                 } else {
1360                         VM_BUG_ON_PAGE(!PageHead(page), page);
1361                         page_remove_rmap(page, true);
1362                         put_page(page);
1363                 }
1364                 ret |= VM_FAULT_WRITE;
1365         }
1366         spin_unlock(vmf->ptl);
1367 out_mn:
1368         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1369 out:
1370         return ret;
1371 out_unlock:
1372         spin_unlock(vmf->ptl);
1373         return ret;
1374 }
1375
1376 /*
1377  * FOLL_FORCE can write to even unwritable pmd's, but only
1378  * after we've gone through a COW cycle and they are dirty.
1379  */
1380 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1381 {
1382         return pmd_write(pmd) ||
1383                ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1384 }
1385
1386 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1387                                    unsigned long addr,
1388                                    pmd_t *pmd,
1389                                    unsigned int flags)
1390 {
1391         struct mm_struct *mm = vma->vm_mm;
1392         struct page *page = NULL;
1393
1394         assert_spin_locked(pmd_lockptr(mm, pmd));
1395
1396         if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1397                 goto out;
1398
1399         /* Avoid dumping huge zero page */
1400         if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1401                 return ERR_PTR(-EFAULT);
1402
1403         /* Full NUMA hinting faults to serialise migration in fault paths */
1404         if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1405                 goto out;
1406
1407         page = pmd_page(*pmd);
1408         VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1409         if (flags & FOLL_TOUCH)
1410                 touch_pmd(vma, addr, pmd);
1411         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1412                 /*
1413                  * We don't mlock() pte-mapped THPs. This way we can avoid
1414                  * leaking mlocked pages into non-VM_LOCKED VMAs.
1415                  *
1416                  * For anon THP:
1417                  *
1418                  * In most cases the pmd is the only mapping of the page as we
1419                  * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1420                  * writable private mappings in populate_vma_page_range().
1421                  *
1422                  * The only scenario when we have the page shared here is if we
1423                  * mlocking read-only mapping shared over fork(). We skip
1424                  * mlocking such pages.
1425                  *
1426                  * For file THP:
1427                  *
1428                  * We can expect PageDoubleMap() to be stable under page lock:
1429                  * for file pages we set it in page_add_file_rmap(), which
1430                  * requires page to be locked.
1431                  */
1432
1433                 if (PageAnon(page) && compound_mapcount(page) != 1)
1434                         goto skip_mlock;
1435                 if (PageDoubleMap(page) || !page->mapping)
1436                         goto skip_mlock;
1437                 if (!trylock_page(page))
1438                         goto skip_mlock;
1439                 lru_add_drain();
1440                 if (page->mapping && !PageDoubleMap(page))
1441                         mlock_vma_page(page);
1442                 unlock_page(page);
1443         }
1444 skip_mlock:
1445         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1446         VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1447         if (flags & FOLL_GET)
1448                 get_page(page);
1449
1450 out:
1451         return page;
1452 }
1453
1454 /* NUMA hinting page fault entry point for trans huge pmds */
1455 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1456 {
1457         struct vm_area_struct *vma = vmf->vma;
1458         struct anon_vma *anon_vma = NULL;
1459         struct page *page;
1460         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1461         int page_nid = -1, this_nid = numa_node_id();
1462         int target_nid, last_cpupid = -1;
1463         bool page_locked;
1464         bool migrated = false;
1465         bool was_writable;
1466         int flags = 0;
1467
1468         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1469         if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1470                 goto out_unlock;
1471
1472         /*
1473          * If there are potential migrations, wait for completion and retry
1474          * without disrupting NUMA hinting information. Do not relock and
1475          * check_same as the page may no longer be mapped.
1476          */
1477         if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1478                 page = pmd_page(*vmf->pmd);
1479                 if (!get_page_unless_zero(page))
1480                         goto out_unlock;
1481                 spin_unlock(vmf->ptl);
1482                 wait_on_page_locked(page);
1483                 put_page(page);
1484                 goto out;
1485         }
1486
1487         page = pmd_page(pmd);
1488         BUG_ON(is_huge_zero_page(page));
1489         page_nid = page_to_nid(page);
1490         last_cpupid = page_cpupid_last(page);
1491         count_vm_numa_event(NUMA_HINT_FAULTS);
1492         if (page_nid == this_nid) {
1493                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1494                 flags |= TNF_FAULT_LOCAL;
1495         }
1496
1497         /* See similar comment in do_numa_page for explanation */
1498         if (!pmd_savedwrite(pmd))
1499                 flags |= TNF_NO_GROUP;
1500
1501         /*
1502          * Acquire the page lock to serialise THP migrations but avoid dropping
1503          * page_table_lock if at all possible
1504          */
1505         page_locked = trylock_page(page);
1506         target_nid = mpol_misplaced(page, vma, haddr);
1507         if (target_nid == -1) {
1508                 /* If the page was locked, there are no parallel migrations */
1509                 if (page_locked)
1510                         goto clear_pmdnuma;
1511         }
1512
1513         /* Migration could have started since the pmd_trans_migrating check */
1514         if (!page_locked) {
1515                 page_nid = -1;
1516                 if (!get_page_unless_zero(page))
1517                         goto out_unlock;
1518                 spin_unlock(vmf->ptl);
1519                 wait_on_page_locked(page);
1520                 put_page(page);
1521                 goto out;
1522         }
1523
1524         /*
1525          * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1526          * to serialises splits
1527          */
1528         get_page(page);
1529         spin_unlock(vmf->ptl);
1530         anon_vma = page_lock_anon_vma_read(page);
1531
1532         /* Confirm the PMD did not change while page_table_lock was released */
1533         spin_lock(vmf->ptl);
1534         if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1535                 unlock_page(page);
1536                 put_page(page);
1537                 page_nid = -1;
1538                 goto out_unlock;
1539         }
1540
1541         /* Bail if we fail to protect against THP splits for any reason */
1542         if (unlikely(!anon_vma)) {
1543                 put_page(page);
1544                 page_nid = -1;
1545                 goto clear_pmdnuma;
1546         }
1547
1548         /*
1549          * Since we took the NUMA fault, we must have observed the !accessible
1550          * bit. Make sure all other CPUs agree with that, to avoid them
1551          * modifying the page we're about to migrate.
1552          *
1553          * Must be done under PTL such that we'll observe the relevant
1554          * inc_tlb_flush_pending().
1555          *
1556          * We are not sure a pending tlb flush here is for a huge page
1557          * mapping or not. Hence use the tlb range variant
1558          */
1559         if (mm_tlb_flush_pending(vma->vm_mm))
1560                 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1561
1562         /*
1563          * Migrate the THP to the requested node, returns with page unlocked
1564          * and access rights restored.
1565          */
1566         spin_unlock(vmf->ptl);
1567
1568         migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1569                                 vmf->pmd, pmd, vmf->address, page, target_nid);
1570         if (migrated) {
1571                 flags |= TNF_MIGRATED;
1572                 page_nid = target_nid;
1573         } else
1574                 flags |= TNF_MIGRATE_FAIL;
1575
1576         goto out;
1577 clear_pmdnuma:
1578         BUG_ON(!PageLocked(page));
1579         was_writable = pmd_savedwrite(pmd);
1580         pmd = pmd_modify(pmd, vma->vm_page_prot);
1581         pmd = pmd_mkyoung(pmd);
1582         if (was_writable)
1583                 pmd = pmd_mkwrite(pmd);
1584         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1585         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1586         unlock_page(page);
1587 out_unlock:
1588         spin_unlock(vmf->ptl);
1589
1590 out:
1591         if (anon_vma)
1592                 page_unlock_anon_vma_read(anon_vma);
1593
1594         if (page_nid != -1)
1595                 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1596                                 flags);
1597
1598         return 0;
1599 }
1600
1601 /*
1602  * Return true if we do MADV_FREE successfully on entire pmd page.
1603  * Otherwise, return false.
1604  */
1605 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1606                 pmd_t *pmd, unsigned long addr, unsigned long next)
1607 {
1608         spinlock_t *ptl;
1609         pmd_t orig_pmd;
1610         struct page *page;
1611         struct mm_struct *mm = tlb->mm;
1612         bool ret = false;
1613
1614         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1615
1616         ptl = pmd_trans_huge_lock(pmd, vma);
1617         if (!ptl)
1618                 goto out_unlocked;
1619
1620         orig_pmd = *pmd;
1621         if (is_huge_zero_pmd(orig_pmd))
1622                 goto out;
1623
1624         if (unlikely(!pmd_present(orig_pmd))) {
1625                 VM_BUG_ON(thp_migration_supported() &&
1626                                   !is_pmd_migration_entry(orig_pmd));
1627                 goto out;
1628         }
1629
1630         page = pmd_page(orig_pmd);
1631         /*
1632          * If other processes are mapping this page, we couldn't discard
1633          * the page unless they all do MADV_FREE so let's skip the page.
1634          */
1635         if (page_mapcount(page) != 1)
1636                 goto out;
1637
1638         if (!trylock_page(page))
1639                 goto out;
1640
1641         /*
1642          * If user want to discard part-pages of THP, split it so MADV_FREE
1643          * will deactivate only them.
1644          */
1645         if (next - addr != HPAGE_PMD_SIZE) {
1646                 get_page(page);
1647                 spin_unlock(ptl);
1648                 split_huge_page(page);
1649                 unlock_page(page);
1650                 put_page(page);
1651                 goto out_unlocked;
1652         }
1653
1654         if (PageDirty(page))
1655                 ClearPageDirty(page);
1656         unlock_page(page);
1657
1658         if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1659                 pmdp_invalidate(vma, addr, pmd);
1660                 orig_pmd = pmd_mkold(orig_pmd);
1661                 orig_pmd = pmd_mkclean(orig_pmd);
1662
1663                 set_pmd_at(mm, addr, pmd, orig_pmd);
1664                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1665         }
1666
1667         mark_page_lazyfree(page);
1668         ret = true;
1669 out:
1670         spin_unlock(ptl);
1671 out_unlocked:
1672         return ret;
1673 }
1674
1675 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1676 {
1677         pgtable_t pgtable;
1678
1679         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1680         pte_free(mm, pgtable);
1681         atomic_long_dec(&mm->nr_ptes);
1682 }
1683
1684 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1685                  pmd_t *pmd, unsigned long addr)
1686 {
1687         pmd_t orig_pmd;
1688         spinlock_t *ptl;
1689
1690         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1691
1692         ptl = __pmd_trans_huge_lock(pmd, vma);
1693         if (!ptl)
1694                 return 0;
1695         /*
1696          * For architectures like ppc64 we look at deposited pgtable
1697          * when calling pmdp_huge_get_and_clear. So do the
1698          * pgtable_trans_huge_withdraw after finishing pmdp related
1699          * operations.
1700          */
1701         orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1702                         tlb->fullmm);
1703         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1704         if (vma_is_dax(vma)) {
1705                 if (arch_needs_pgtable_deposit())
1706                         zap_deposited_table(tlb->mm, pmd);
1707                 spin_unlock(ptl);
1708                 if (is_huge_zero_pmd(orig_pmd))
1709                         tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1710         } else if (is_huge_zero_pmd(orig_pmd)) {
1711                 zap_deposited_table(tlb->mm, pmd);
1712                 spin_unlock(ptl);
1713                 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1714         } else {
1715                 struct page *page = NULL;
1716                 int flush_needed = 1;
1717
1718                 if (pmd_present(orig_pmd)) {
1719                         page = pmd_page(orig_pmd);
1720                         page_remove_rmap(page, true);
1721                         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1722                         VM_BUG_ON_PAGE(!PageHead(page), page);
1723                 } else if (thp_migration_supported()) {
1724                         swp_entry_t entry;
1725
1726                         VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1727                         entry = pmd_to_swp_entry(orig_pmd);
1728                         page = pfn_to_page(swp_offset(entry));
1729                         flush_needed = 0;
1730                 } else
1731                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1732
1733                 if (PageAnon(page)) {
1734                         zap_deposited_table(tlb->mm, pmd);
1735                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1736                 } else {
1737                         if (arch_needs_pgtable_deposit())
1738                                 zap_deposited_table(tlb->mm, pmd);
1739                         add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1740                 }
1741
1742                 spin_unlock(ptl);
1743                 if (flush_needed)
1744                         tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1745         }
1746         return 1;
1747 }
1748
1749 #ifndef pmd_move_must_withdraw
1750 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1751                                          spinlock_t *old_pmd_ptl,
1752                                          struct vm_area_struct *vma)
1753 {
1754         /*
1755          * With split pmd lock we also need to move preallocated
1756          * PTE page table if new_pmd is on different PMD page table.
1757          *
1758          * We also don't deposit and withdraw tables for file pages.
1759          */
1760         return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1761 }
1762 #endif
1763
1764 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1765 {
1766 #ifdef CONFIG_MEM_SOFT_DIRTY
1767         if (unlikely(is_pmd_migration_entry(pmd)))
1768                 pmd = pmd_swp_mksoft_dirty(pmd);
1769         else if (pmd_present(pmd))
1770                 pmd = pmd_mksoft_dirty(pmd);
1771 #endif
1772         return pmd;
1773 }
1774
1775 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1776                   unsigned long new_addr, unsigned long old_end,
1777                   pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1778 {
1779         spinlock_t *old_ptl, *new_ptl;
1780         pmd_t pmd;
1781         struct mm_struct *mm = vma->vm_mm;
1782         bool force_flush = false;
1783
1784         if ((old_addr & ~HPAGE_PMD_MASK) ||
1785             (new_addr & ~HPAGE_PMD_MASK) ||
1786             old_end - old_addr < HPAGE_PMD_SIZE)
1787                 return false;
1788
1789         /*
1790          * The destination pmd shouldn't be established, free_pgtables()
1791          * should have release it.
1792          */
1793         if (WARN_ON(!pmd_none(*new_pmd))) {
1794                 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1795                 return false;
1796         }
1797
1798         /*
1799          * We don't have to worry about the ordering of src and dst
1800          * ptlocks because exclusive mmap_sem prevents deadlock.
1801          */
1802         old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1803         if (old_ptl) {
1804                 new_ptl = pmd_lockptr(mm, new_pmd);
1805                 if (new_ptl != old_ptl)
1806                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1807                 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1808                 if (pmd_present(pmd) && pmd_dirty(pmd))
1809                         force_flush = true;
1810                 VM_BUG_ON(!pmd_none(*new_pmd));
1811
1812                 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1813                         pgtable_t pgtable;
1814                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1815                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1816                 }
1817                 pmd = move_soft_dirty_pmd(pmd);
1818                 set_pmd_at(mm, new_addr, new_pmd, pmd);
1819                 if (new_ptl != old_ptl)
1820                         spin_unlock(new_ptl);
1821                 if (force_flush)
1822                         flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1823                 else
1824                         *need_flush = true;
1825                 spin_unlock(old_ptl);
1826                 return true;
1827         }
1828         return false;
1829 }
1830
1831 /*
1832  * Returns
1833  *  - 0 if PMD could not be locked
1834  *  - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1835  *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
1836  */
1837 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1838                 unsigned long addr, pgprot_t newprot, int prot_numa)
1839 {
1840         struct mm_struct *mm = vma->vm_mm;
1841         spinlock_t *ptl;
1842         pmd_t entry;
1843         bool preserve_write;
1844         int ret;
1845
1846         ptl = __pmd_trans_huge_lock(pmd, vma);
1847         if (!ptl)
1848                 return 0;
1849
1850         preserve_write = prot_numa && pmd_write(*pmd);
1851         ret = 1;
1852
1853 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1854         if (is_swap_pmd(*pmd)) {
1855                 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1856
1857                 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1858                 if (is_write_migration_entry(entry)) {
1859                         pmd_t newpmd;
1860                         /*
1861                          * A protection check is difficult so
1862                          * just be safe and disable write
1863                          */
1864                         make_migration_entry_read(&entry);
1865                         newpmd = swp_entry_to_pmd(entry);
1866                         if (pmd_swp_soft_dirty(*pmd))
1867                                 newpmd = pmd_swp_mksoft_dirty(newpmd);
1868                         set_pmd_at(mm, addr, pmd, newpmd);
1869                 }
1870                 goto unlock;
1871         }
1872 #endif
1873
1874         /*
1875          * Avoid trapping faults against the zero page. The read-only
1876          * data is likely to be read-cached on the local CPU and
1877          * local/remote hits to the zero page are not interesting.
1878          */
1879         if (prot_numa && is_huge_zero_pmd(*pmd))
1880                 goto unlock;
1881
1882         if (prot_numa && pmd_protnone(*pmd))
1883                 goto unlock;
1884
1885         /*
1886          * In case prot_numa, we are under down_read(mmap_sem). It's critical
1887          * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1888          * which is also under down_read(mmap_sem):
1889          *
1890          *      CPU0:                           CPU1:
1891          *                              change_huge_pmd(prot_numa=1)
1892          *                               pmdp_huge_get_and_clear_notify()
1893          * madvise_dontneed()
1894          *  zap_pmd_range()
1895          *   pmd_trans_huge(*pmd) == 0 (without ptl)
1896          *   // skip the pmd
1897          *                               set_pmd_at();
1898          *                               // pmd is re-established
1899          *
1900          * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1901          * which may break userspace.
1902          *
1903          * pmdp_invalidate() is required to make sure we don't miss
1904          * dirty/young flags set by hardware.
1905          */
1906         entry = *pmd;
1907         pmdp_invalidate(vma, addr, pmd);
1908
1909         /*
1910          * Recover dirty/young flags.  It relies on pmdp_invalidate to not
1911          * corrupt them.
1912          */
1913         if (pmd_dirty(*pmd))
1914                 entry = pmd_mkdirty(entry);
1915         if (pmd_young(*pmd))
1916                 entry = pmd_mkyoung(entry);
1917
1918         entry = pmd_modify(entry, newprot);
1919         if (preserve_write)
1920                 entry = pmd_mk_savedwrite(entry);
1921         ret = HPAGE_PMD_NR;
1922         set_pmd_at(mm, addr, pmd, entry);
1923         BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1924 unlock:
1925         spin_unlock(ptl);
1926         return ret;
1927 }
1928
1929 /*
1930  * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1931  *
1932  * Note that if it returns page table lock pointer, this routine returns without
1933  * unlocking page table lock. So callers must unlock it.
1934  */
1935 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1936 {
1937         spinlock_t *ptl;
1938         ptl = pmd_lock(vma->vm_mm, pmd);
1939         if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1940                         pmd_devmap(*pmd)))
1941                 return ptl;
1942         spin_unlock(ptl);
1943         return NULL;
1944 }
1945
1946 /*
1947  * Returns true if a given pud maps a thp, false otherwise.
1948  *
1949  * Note that if it returns true, this routine returns without unlocking page
1950  * table lock. So callers must unlock it.
1951  */
1952 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1953 {
1954         spinlock_t *ptl;
1955
1956         ptl = pud_lock(vma->vm_mm, pud);
1957         if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1958                 return ptl;
1959         spin_unlock(ptl);
1960         return NULL;
1961 }
1962
1963 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1964 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1965                  pud_t *pud, unsigned long addr)
1966 {
1967         pud_t orig_pud;
1968         spinlock_t *ptl;
1969
1970         ptl = __pud_trans_huge_lock(pud, vma);
1971         if (!ptl)
1972                 return 0;
1973         /*
1974          * For architectures like ppc64 we look at deposited pgtable
1975          * when calling pudp_huge_get_and_clear. So do the
1976          * pgtable_trans_huge_withdraw after finishing pudp related
1977          * operations.
1978          */
1979         orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1980                         tlb->fullmm);
1981         tlb_remove_pud_tlb_entry(tlb, pud, addr);
1982         if (vma_is_dax(vma)) {
1983                 spin_unlock(ptl);
1984                 /* No zero page support yet */
1985         } else {
1986                 /* No support for anonymous PUD pages yet */
1987                 BUG();
1988         }
1989         return 1;
1990 }
1991
1992 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1993                 unsigned long haddr)
1994 {
1995         VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1996         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1997         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1998         VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1999
2000         count_vm_event(THP_SPLIT_PUD);
2001
2002         pudp_huge_clear_flush_notify(vma, haddr, pud);
2003 }
2004
2005 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2006                 unsigned long address)
2007 {
2008         spinlock_t *ptl;
2009         struct mm_struct *mm = vma->vm_mm;
2010         unsigned long haddr = address & HPAGE_PUD_MASK;
2011
2012         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2013         ptl = pud_lock(mm, pud);
2014         if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2015                 goto out;
2016         __split_huge_pud_locked(vma, pud, haddr);
2017
2018 out:
2019         spin_unlock(ptl);
2020         mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PUD_SIZE);
2021 }
2022 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2023
2024 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2025                 unsigned long haddr, pmd_t *pmd)
2026 {
2027         struct mm_struct *mm = vma->vm_mm;
2028         pgtable_t pgtable;
2029         pmd_t _pmd;
2030         int i;
2031
2032         /* leave pmd empty until pte is filled */
2033         pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2034
2035         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2036         pmd_populate(mm, &_pmd, pgtable);
2037
2038         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2039                 pte_t *pte, entry;
2040                 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2041                 entry = pte_mkspecial(entry);
2042                 pte = pte_offset_map(&_pmd, haddr);
2043                 VM_BUG_ON(!pte_none(*pte));
2044                 set_pte_at(mm, haddr, pte, entry);
2045                 pte_unmap(pte);
2046         }
2047         smp_wmb(); /* make pte visible before pmd */
2048         pmd_populate(mm, pmd, pgtable);
2049 }
2050
2051 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2052                 unsigned long haddr, bool freeze)
2053 {
2054         struct mm_struct *mm = vma->vm_mm;
2055         struct page *page;
2056         pgtable_t pgtable;
2057         pmd_t _pmd;
2058         bool young, write, dirty, soft_dirty, pmd_migration = false;
2059         unsigned long addr;
2060         int i;
2061
2062         VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2063         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2064         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2065         VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2066                                 && !pmd_devmap(*pmd));
2067
2068         count_vm_event(THP_SPLIT_PMD);
2069
2070         if (!vma_is_anonymous(vma)) {
2071                 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2072                 /*
2073                  * We are going to unmap this huge page. So
2074                  * just go ahead and zap it
2075                  */
2076                 if (arch_needs_pgtable_deposit())
2077                         zap_deposited_table(mm, pmd);
2078                 if (vma_is_dax(vma))
2079                         return;
2080                 page = pmd_page(_pmd);
2081                 if (!PageReferenced(page) && pmd_young(_pmd))
2082                         SetPageReferenced(page);
2083                 page_remove_rmap(page, true);
2084                 put_page(page);
2085                 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2086                 return;
2087         } else if (is_huge_zero_pmd(*pmd)) {
2088                 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2089         }
2090
2091 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2092         pmd_migration = is_pmd_migration_entry(*pmd);
2093         if (pmd_migration) {
2094                 swp_entry_t entry;
2095
2096                 entry = pmd_to_swp_entry(*pmd);
2097                 page = pfn_to_page(swp_offset(entry));
2098         } else
2099 #endif
2100                 page = pmd_page(*pmd);
2101         VM_BUG_ON_PAGE(!page_count(page), page);
2102         page_ref_add(page, HPAGE_PMD_NR - 1);
2103         write = pmd_write(*pmd);
2104         young = pmd_young(*pmd);
2105         dirty = pmd_dirty(*pmd);
2106         soft_dirty = pmd_soft_dirty(*pmd);
2107
2108         pmdp_huge_split_prepare(vma, haddr, pmd);
2109         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2110         pmd_populate(mm, &_pmd, pgtable);
2111
2112         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2113                 pte_t entry, *pte;
2114                 /*
2115                  * Note that NUMA hinting access restrictions are not
2116                  * transferred to avoid any possibility of altering
2117                  * permissions across VMAs.
2118                  */
2119                 if (freeze || pmd_migration) {
2120                         swp_entry_t swp_entry;
2121                         swp_entry = make_migration_entry(page + i, write);
2122                         entry = swp_entry_to_pte(swp_entry);
2123                         if (soft_dirty)
2124                                 entry = pte_swp_mksoft_dirty(entry);
2125                 } else {
2126                         entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2127                         entry = maybe_mkwrite(entry, vma);
2128                         if (!write)
2129                                 entry = pte_wrprotect(entry);
2130                         if (!young)
2131                                 entry = pte_mkold(entry);
2132                         if (soft_dirty)
2133                                 entry = pte_mksoft_dirty(entry);
2134                 }
2135                 if (dirty)
2136                         SetPageDirty(page + i);
2137                 pte = pte_offset_map(&_pmd, addr);
2138                 BUG_ON(!pte_none(*pte));
2139                 set_pte_at(mm, addr, pte, entry);
2140                 atomic_inc(&page[i]._mapcount);
2141                 pte_unmap(pte);
2142         }
2143
2144         /*
2145          * Set PG_double_map before dropping compound_mapcount to avoid
2146          * false-negative page_mapped().
2147          */
2148         if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2149                 for (i = 0; i < HPAGE_PMD_NR; i++)
2150                         atomic_inc(&page[i]._mapcount);
2151         }
2152
2153         if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2154                 /* Last compound_mapcount is gone. */
2155                 __dec_node_page_state(page, NR_ANON_THPS);
2156                 if (TestClearPageDoubleMap(page)) {
2157                         /* No need in mapcount reference anymore */
2158                         for (i = 0; i < HPAGE_PMD_NR; i++)
2159                                 atomic_dec(&page[i]._mapcount);
2160                 }
2161         }
2162
2163         smp_wmb(); /* make pte visible before pmd */
2164         /*
2165          * Up to this point the pmd is present and huge and userland has the
2166          * whole access to the hugepage during the split (which happens in
2167          * place). If we overwrite the pmd with the not-huge version pointing
2168          * to the pte here (which of course we could if all CPUs were bug
2169          * free), userland could trigger a small page size TLB miss on the
2170          * small sized TLB while the hugepage TLB entry is still established in
2171          * the huge TLB. Some CPU doesn't like that.
2172          * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2173          * 383 on page 93. Intel should be safe but is also warns that it's
2174          * only safe if the permission and cache attributes of the two entries
2175          * loaded in the two TLB is identical (which should be the case here).
2176          * But it is generally safer to never allow small and huge TLB entries
2177          * for the same virtual address to be loaded simultaneously. So instead
2178          * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2179          * current pmd notpresent (atomically because here the pmd_trans_huge
2180          * and pmd_trans_splitting must remain set at all times on the pmd
2181          * until the split is complete for this pmd), then we flush the SMP TLB
2182          * and finally we write the non-huge version of the pmd entry with
2183          * pmd_populate.
2184          */
2185         pmdp_invalidate(vma, haddr, pmd);
2186         pmd_populate(mm, pmd, pgtable);
2187
2188         if (freeze) {
2189                 for (i = 0; i < HPAGE_PMD_NR; i++) {
2190                         page_remove_rmap(page + i, false);
2191                         put_page(page + i);
2192                 }
2193         }
2194 }
2195
2196 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2197                 unsigned long address, bool freeze, struct page *page)
2198 {
2199         spinlock_t *ptl;
2200         struct mm_struct *mm = vma->vm_mm;
2201         unsigned long haddr = address & HPAGE_PMD_MASK;
2202
2203         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2204         ptl = pmd_lock(mm, pmd);
2205
2206         /*
2207          * If caller asks to setup a migration entries, we need a page to check
2208          * pmd against. Otherwise we can end up replacing wrong page.
2209          */
2210         VM_BUG_ON(freeze && !page);
2211         if (page && page != pmd_page(*pmd))
2212                 goto out;
2213
2214         if (pmd_trans_huge(*pmd)) {
2215                 page = pmd_page(*pmd);
2216                 if (PageMlocked(page))
2217                         clear_page_mlock(page);
2218         } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2219                 goto out;
2220         __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2221 out:
2222         spin_unlock(ptl);
2223         mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
2224 }
2225
2226 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2227                 bool freeze, struct page *page)
2228 {
2229         pgd_t *pgd;
2230         p4d_t *p4d;
2231         pud_t *pud;
2232         pmd_t *pmd;
2233
2234         pgd = pgd_offset(vma->vm_mm, address);
2235         if (!pgd_present(*pgd))
2236                 return;
2237
2238         p4d = p4d_offset(pgd, address);
2239         if (!p4d_present(*p4d))
2240                 return;
2241
2242         pud = pud_offset(p4d, address);
2243         if (!pud_present(*pud))
2244                 return;
2245
2246         pmd = pmd_offset(pud, address);
2247
2248         __split_huge_pmd(vma, pmd, address, freeze, page);
2249 }
2250
2251 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2252                              unsigned long start,
2253                              unsigned long end,
2254                              long adjust_next)
2255 {
2256         /*
2257          * If the new start address isn't hpage aligned and it could
2258          * previously contain an hugepage: check if we need to split
2259          * an huge pmd.
2260          */
2261         if (start & ~HPAGE_PMD_MASK &&
2262             (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2263             (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2264                 split_huge_pmd_address(vma, start, false, NULL);
2265
2266         /*
2267          * If the new end address isn't hpage aligned and it could
2268          * previously contain an hugepage: check if we need to split
2269          * an huge pmd.
2270          */
2271         if (end & ~HPAGE_PMD_MASK &&
2272             (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2273             (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2274                 split_huge_pmd_address(vma, end, false, NULL);
2275
2276         /*
2277          * If we're also updating the vma->vm_next->vm_start, if the new
2278          * vm_next->vm_start isn't page aligned and it could previously
2279          * contain an hugepage: check if we need to split an huge pmd.
2280          */
2281         if (adjust_next > 0) {
2282                 struct vm_area_struct *next = vma->vm_next;
2283                 unsigned long nstart = next->vm_start;
2284                 nstart += adjust_next << PAGE_SHIFT;
2285                 if (nstart & ~HPAGE_PMD_MASK &&
2286                     (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2287                     (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2288                         split_huge_pmd_address(next, nstart, false, NULL);
2289         }
2290 }
2291
2292 static void freeze_page(struct page *page)
2293 {
2294         enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2295                 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2296         bool unmap_success;
2297
2298         VM_BUG_ON_PAGE(!PageHead(page), page);
2299
2300         if (PageAnon(page))
2301                 ttu_flags |= TTU_SPLIT_FREEZE;
2302
2303         unmap_success = try_to_unmap(page, ttu_flags);
2304         VM_BUG_ON_PAGE(!unmap_success, page);
2305 }
2306
2307 static void unfreeze_page(struct page *page)
2308 {
2309         int i;
2310         if (PageTransHuge(page)) {
2311                 remove_migration_ptes(page, page, true);
2312         } else {
2313                 for (i = 0; i < HPAGE_PMD_NR; i++)
2314                         remove_migration_ptes(page + i, page + i, true);
2315         }
2316 }
2317
2318 static void __split_huge_page_tail(struct page *head, int tail,
2319                 struct lruvec *lruvec, struct list_head *list)
2320 {
2321         struct page *page_tail = head + tail;
2322
2323         VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2324         VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
2325
2326         /*
2327          * tail_page->_refcount is zero and not changing from under us. But
2328          * get_page_unless_zero() may be running from under us on the
2329          * tail_page. If we used atomic_set() below instead of atomic_inc() or
2330          * atomic_add(), we would then run atomic_set() concurrently with
2331          * get_page_unless_zero(), and atomic_set() is implemented in C not
2332          * using locked ops. spin_unlock on x86 sometime uses locked ops
2333          * because of PPro errata 66, 92, so unless somebody can guarantee
2334          * atomic_set() here would be safe on all archs (and not only on x86),
2335          * it's safer to use atomic_inc()/atomic_add().
2336          */
2337         if (PageAnon(head) && !PageSwapCache(head)) {
2338                 page_ref_inc(page_tail);
2339         } else {
2340                 /* Additional pin to radix tree */
2341                 page_ref_add(page_tail, 2);
2342         }
2343
2344         page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2345         page_tail->flags |= (head->flags &
2346                         ((1L << PG_referenced) |
2347                          (1L << PG_swapbacked) |
2348                          (1L << PG_swapcache) |
2349                          (1L << PG_mlocked) |
2350                          (1L << PG_uptodate) |
2351                          (1L << PG_active) |
2352                          (1L << PG_locked) |
2353                          (1L << PG_unevictable) |
2354                          (1L << PG_dirty)));
2355
2356         /*
2357          * After clearing PageTail the gup refcount can be released.
2358          * Page flags also must be visible before we make the page non-compound.
2359          */
2360         smp_wmb();
2361
2362         clear_compound_head(page_tail);
2363
2364         if (page_is_young(head))
2365                 set_page_young(page_tail);
2366         if (page_is_idle(head))
2367                 set_page_idle(page_tail);
2368
2369         /* ->mapping in first tail page is compound_mapcount */
2370         VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2371                         page_tail);
2372         page_tail->mapping = head->mapping;
2373
2374         page_tail->index = head->index + tail;
2375         page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2376         lru_add_page_tail(head, page_tail, lruvec, list);
2377 }
2378
2379 static void __split_huge_page(struct page *page, struct list_head *list,
2380                 unsigned long flags)
2381 {
2382         struct page *head = compound_head(page);
2383         struct zone *zone = page_zone(head);
2384         struct lruvec *lruvec;
2385         pgoff_t end = -1;
2386         int i;
2387
2388         lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2389
2390         /* complete memcg works before add pages to LRU */
2391         mem_cgroup_split_huge_fixup(head);
2392
2393         if (!PageAnon(page))
2394                 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2395
2396         for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2397                 __split_huge_page_tail(head, i, lruvec, list);
2398                 /* Some pages can be beyond i_size: drop them from page cache */
2399                 if (head[i].index >= end) {
2400                         __ClearPageDirty(head + i);
2401                         __delete_from_page_cache(head + i, NULL);
2402                         if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2403                                 shmem_uncharge(head->mapping->host, 1);
2404                         put_page(head + i);
2405                 }
2406         }
2407
2408         ClearPageCompound(head);
2409         /* See comment in __split_huge_page_tail() */
2410         if (PageAnon(head)) {
2411                 /* Additional pin to radix tree of swap cache */
2412                 if (PageSwapCache(head))
2413                         page_ref_add(head, 2);
2414                 else
2415                         page_ref_inc(head);
2416         } else {
2417                 /* Additional pin to radix tree */
2418                 page_ref_add(head, 2);
2419                 spin_unlock(&head->mapping->tree_lock);
2420         }
2421
2422         spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2423
2424         unfreeze_page(head);
2425
2426         for (i = 0; i < HPAGE_PMD_NR; i++) {
2427                 struct page *subpage = head + i;
2428                 if (subpage == page)
2429                         continue;
2430                 unlock_page(subpage);
2431
2432                 /*
2433                  * Subpages may be freed if there wasn't any mapping
2434                  * like if add_to_swap() is running on a lru page that
2435                  * had its mapping zapped. And freeing these pages
2436                  * requires taking the lru_lock so we do the put_page
2437                  * of the tail pages after the split is complete.
2438                  */
2439                 put_page(subpage);
2440         }
2441 }
2442
2443 int total_mapcount(struct page *page)
2444 {
2445         int i, compound, ret;
2446
2447         VM_BUG_ON_PAGE(PageTail(page), page);
2448
2449         if (likely(!PageCompound(page)))
2450                 return atomic_read(&page->_mapcount) + 1;
2451
2452         compound = compound_mapcount(page);
2453         if (PageHuge(page))
2454                 return compound;
2455         ret = compound;
2456         for (i = 0; i < HPAGE_PMD_NR; i++)
2457                 ret += atomic_read(&page[i]._mapcount) + 1;
2458         /* File pages has compound_mapcount included in _mapcount */
2459         if (!PageAnon(page))
2460                 return ret - compound * HPAGE_PMD_NR;
2461         if (PageDoubleMap(page))
2462                 ret -= HPAGE_PMD_NR;
2463         return ret;
2464 }
2465
2466 /*
2467  * This calculates accurately how many mappings a transparent hugepage
2468  * has (unlike page_mapcount() which isn't fully accurate). This full
2469  * accuracy is primarily needed to know if copy-on-write faults can
2470  * reuse the page and change the mapping to read-write instead of
2471  * copying them. At the same time this returns the total_mapcount too.
2472  *
2473  * The function returns the highest mapcount any one of the subpages
2474  * has. If the return value is one, even if different processes are
2475  * mapping different subpages of the transparent hugepage, they can
2476  * all reuse it, because each process is reusing a different subpage.
2477  *
2478  * The total_mapcount is instead counting all virtual mappings of the
2479  * subpages. If the total_mapcount is equal to "one", it tells the
2480  * caller all mappings belong to the same "mm" and in turn the
2481  * anon_vma of the transparent hugepage can become the vma->anon_vma
2482  * local one as no other process may be mapping any of the subpages.
2483  *
2484  * It would be more accurate to replace page_mapcount() with
2485  * page_trans_huge_mapcount(), however we only use
2486  * page_trans_huge_mapcount() in the copy-on-write faults where we
2487  * need full accuracy to avoid breaking page pinning, because
2488  * page_trans_huge_mapcount() is slower than page_mapcount().
2489  */
2490 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2491 {
2492         int i, ret, _total_mapcount, mapcount;
2493
2494         /* hugetlbfs shouldn't call it */
2495         VM_BUG_ON_PAGE(PageHuge(page), page);
2496
2497         if (likely(!PageTransCompound(page))) {
2498                 mapcount = atomic_read(&page->_mapcount) + 1;
2499                 if (total_mapcount)
2500                         *total_mapcount = mapcount;
2501                 return mapcount;
2502         }
2503
2504         page = compound_head(page);
2505
2506         _total_mapcount = ret = 0;
2507         for (i = 0; i < HPAGE_PMD_NR; i++) {
2508                 mapcount = atomic_read(&page[i]._mapcount) + 1;
2509                 ret = max(ret, mapcount);
2510                 _total_mapcount += mapcount;
2511         }
2512         if (PageDoubleMap(page)) {
2513                 ret -= 1;
2514                 _total_mapcount -= HPAGE_PMD_NR;
2515         }
2516         mapcount = compound_mapcount(page);
2517         ret += mapcount;
2518         _total_mapcount += mapcount;
2519         if (total_mapcount)
2520                 *total_mapcount = _total_mapcount;
2521         return ret;
2522 }
2523
2524 /* Racy check whether the huge page can be split */
2525 bool can_split_huge_page(struct page *page, int *pextra_pins)
2526 {
2527         int extra_pins;
2528
2529         /* Additional pins from radix tree */
2530         if (PageAnon(page))
2531                 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2532         else
2533                 extra_pins = HPAGE_PMD_NR;
2534         if (pextra_pins)
2535                 *pextra_pins = extra_pins;
2536         return total_mapcount(page) == page_count(page) - extra_pins - 1;
2537 }
2538
2539 /*
2540  * This function splits huge page into normal pages. @page can point to any
2541  * subpage of huge page to split. Split doesn't change the position of @page.
2542  *
2543  * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2544  * The huge page must be locked.
2545  *
2546  * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2547  *
2548  * Both head page and tail pages will inherit mapping, flags, and so on from
2549  * the hugepage.
2550  *
2551  * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2552  * they are not mapped.
2553  *
2554  * Returns 0 if the hugepage is split successfully.
2555  * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2556  * us.
2557  */
2558 int split_huge_page_to_list(struct page *page, struct list_head *list)
2559 {
2560         struct page *head = compound_head(page);
2561         struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2562         struct anon_vma *anon_vma = NULL;
2563         struct address_space *mapping = NULL;
2564         int count, mapcount, extra_pins, ret;
2565         bool mlocked;
2566         unsigned long flags;
2567
2568         VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2569         VM_BUG_ON_PAGE(!PageLocked(page), page);
2570         VM_BUG_ON_PAGE(!PageCompound(page), page);
2571
2572         if (PageWriteback(page))
2573                 return -EBUSY;
2574
2575         if (PageAnon(head)) {
2576                 /*
2577                  * The caller does not necessarily hold an mmap_sem that would
2578                  * prevent the anon_vma disappearing so we first we take a
2579                  * reference to it and then lock the anon_vma for write. This
2580                  * is similar to page_lock_anon_vma_read except the write lock
2581                  * is taken to serialise against parallel split or collapse
2582                  * operations.
2583                  */
2584                 anon_vma = page_get_anon_vma(head);
2585                 if (!anon_vma) {
2586                         ret = -EBUSY;
2587                         goto out;
2588                 }
2589                 mapping = NULL;
2590                 anon_vma_lock_write(anon_vma);
2591         } else {
2592                 mapping = head->mapping;
2593
2594                 /* Truncated ? */
2595                 if (!mapping) {
2596                         ret = -EBUSY;
2597                         goto out;
2598                 }
2599
2600                 anon_vma = NULL;
2601                 i_mmap_lock_read(mapping);
2602         }
2603
2604         /*
2605          * Racy check if we can split the page, before freeze_page() will
2606          * split PMDs
2607          */
2608         if (!can_split_huge_page(head, &extra_pins)) {
2609                 ret = -EBUSY;
2610                 goto out_unlock;
2611         }
2612
2613         mlocked = PageMlocked(page);
2614         freeze_page(head);
2615         VM_BUG_ON_PAGE(compound_mapcount(head), head);
2616
2617         /* Make sure the page is not on per-CPU pagevec as it takes pin */
2618         if (mlocked)
2619                 lru_add_drain();
2620
2621         /* prevent PageLRU to go away from under us, and freeze lru stats */
2622         spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2623
2624         if (mapping) {
2625                 void **pslot;
2626
2627                 spin_lock(&mapping->tree_lock);
2628                 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2629                                 page_index(head));
2630                 /*
2631                  * Check if the head page is present in radix tree.
2632                  * We assume all tail are present too, if head is there.
2633                  */
2634                 if (radix_tree_deref_slot_protected(pslot,
2635                                         &mapping->tree_lock) != head)
2636                         goto fail;
2637         }
2638
2639         /* Prevent deferred_split_scan() touching ->_refcount */
2640         spin_lock(&pgdata->split_queue_lock);
2641         count = page_count(head);
2642         mapcount = total_mapcount(head);
2643         if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2644                 if (!list_empty(page_deferred_list(head))) {
2645                         pgdata->split_queue_len--;
2646                         list_del(page_deferred_list(head));
2647                 }
2648                 if (mapping)
2649                         __dec_node_page_state(page, NR_SHMEM_THPS);
2650                 spin_unlock(&pgdata->split_queue_lock);
2651                 __split_huge_page(page, list, flags);
2652                 if (PageSwapCache(head)) {
2653                         swp_entry_t entry = { .val = page_private(head) };
2654
2655                         ret = split_swap_cluster(entry);
2656                 } else
2657                         ret = 0;
2658         } else {
2659                 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2660                         pr_alert("total_mapcount: %u, page_count(): %u\n",
2661                                         mapcount, count);
2662                         if (PageTail(page))
2663                                 dump_page(head, NULL);
2664                         dump_page(page, "total_mapcount(head) > 0");
2665                         BUG();
2666                 }
2667                 spin_unlock(&pgdata->split_queue_lock);
2668 fail:           if (mapping)
2669                         spin_unlock(&mapping->tree_lock);
2670                 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2671                 unfreeze_page(head);
2672                 ret = -EBUSY;
2673         }
2674
2675 out_unlock:
2676         if (anon_vma) {
2677                 anon_vma_unlock_write(anon_vma);
2678                 put_anon_vma(anon_vma);
2679         }
2680         if (mapping)
2681                 i_mmap_unlock_read(mapping);
2682 out:
2683         count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2684         return ret;
2685 }
2686
2687 void free_transhuge_page(struct page *page)
2688 {
2689         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2690         unsigned long flags;
2691
2692         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2693         if (!list_empty(page_deferred_list(page))) {
2694                 pgdata->split_queue_len--;
2695                 list_del(page_deferred_list(page));
2696         }
2697         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2698         free_compound_page(page);
2699 }
2700
2701 void deferred_split_huge_page(struct page *page)
2702 {
2703         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2704         unsigned long flags;
2705
2706         VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2707
2708         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2709         if (list_empty(page_deferred_list(page))) {
2710                 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2711                 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2712                 pgdata->split_queue_len++;
2713         }
2714         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2715 }
2716
2717 static unsigned long deferred_split_count(struct shrinker *shrink,
2718                 struct shrink_control *sc)
2719 {
2720         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2721         return READ_ONCE(pgdata->split_queue_len);
2722 }
2723
2724 static unsigned long deferred_split_scan(struct shrinker *shrink,
2725                 struct shrink_control *sc)
2726 {
2727         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2728         unsigned long flags;
2729         LIST_HEAD(list), *pos, *next;
2730         struct page *page;
2731         int split = 0;
2732
2733         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2734         /* Take pin on all head pages to avoid freeing them under us */
2735         list_for_each_safe(pos, next, &pgdata->split_queue) {
2736                 page = list_entry((void *)pos, struct page, mapping);
2737                 page = compound_head(page);
2738                 if (get_page_unless_zero(page)) {
2739                         list_move(page_deferred_list(page), &list);
2740                 } else {
2741                         /* We lost race with put_compound_page() */
2742                         list_del_init(page_deferred_list(page));
2743                         pgdata->split_queue_len--;
2744                 }
2745                 if (!--sc->nr_to_scan)
2746                         break;
2747         }
2748         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2749
2750         list_for_each_safe(pos, next, &list) {
2751                 page = list_entry((void *)pos, struct page, mapping);
2752                 lock_page(page);
2753                 /* split_huge_page() removes page from list on success */
2754                 if (!split_huge_page(page))
2755                         split++;
2756                 unlock_page(page);
2757                 put_page(page);
2758         }
2759
2760         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2761         list_splice_tail(&list, &pgdata->split_queue);
2762         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2763
2764         /*
2765          * Stop shrinker if we didn't split any page, but the queue is empty.
2766          * This can happen if pages were freed under us.
2767          */
2768         if (!split && list_empty(&pgdata->split_queue))
2769                 return SHRINK_STOP;
2770         return split;
2771 }
2772
2773 static struct shrinker deferred_split_shrinker = {
2774         .count_objects = deferred_split_count,
2775         .scan_objects = deferred_split_scan,
2776         .seeks = DEFAULT_SEEKS,
2777         .flags = SHRINKER_NUMA_AWARE,
2778 };
2779
2780 #ifdef CONFIG_DEBUG_FS
2781 static int split_huge_pages_set(void *data, u64 val)
2782 {
2783         struct zone *zone;
2784         struct page *page;
2785         unsigned long pfn, max_zone_pfn;
2786         unsigned long total = 0, split = 0;
2787
2788         if (val != 1)
2789                 return -EINVAL;
2790
2791         for_each_populated_zone(zone) {
2792                 max_zone_pfn = zone_end_pfn(zone);
2793                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2794                         if (!pfn_valid(pfn))
2795                                 continue;
2796
2797                         page = pfn_to_page(pfn);
2798                         if (!get_page_unless_zero(page))
2799                                 continue;
2800
2801                         if (zone != page_zone(page))
2802                                 goto next;
2803
2804                         if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2805                                 goto next;
2806
2807                         total++;
2808                         lock_page(page);
2809                         if (!split_huge_page(page))
2810                                 split++;
2811                         unlock_page(page);
2812 next:
2813                         put_page(page);
2814                 }
2815         }
2816
2817         pr_info("%lu of %lu THP split\n", split, total);
2818
2819         return 0;
2820 }
2821 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2822                 "%llu\n");
2823
2824 static int __init split_huge_pages_debugfs(void)
2825 {
2826         void *ret;
2827
2828         ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2829                         &split_huge_pages_fops);
2830         if (!ret)
2831                 pr_warn("Failed to create split_huge_pages in debugfs");
2832         return 0;
2833 }
2834 late_initcall(split_huge_pages_debugfs);
2835 #endif
2836
2837 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2838 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2839                 struct page *page)
2840 {
2841         struct vm_area_struct *vma = pvmw->vma;
2842         struct mm_struct *mm = vma->vm_mm;
2843         unsigned long address = pvmw->address;
2844         pmd_t pmdval;
2845         swp_entry_t entry;
2846         pmd_t pmdswp;
2847
2848         if (!(pvmw->pmd && !pvmw->pte))
2849                 return;
2850
2851         mmu_notifier_invalidate_range_start(mm, address,
2852                         address + HPAGE_PMD_SIZE);
2853
2854         flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2855         pmdval = *pvmw->pmd;
2856         pmdp_invalidate(vma, address, pvmw->pmd);
2857         if (pmd_dirty(pmdval))
2858                 set_page_dirty(page);
2859         entry = make_migration_entry(page, pmd_write(pmdval));
2860         pmdswp = swp_entry_to_pmd(entry);
2861         if (pmd_soft_dirty(pmdval))
2862                 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2863         set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2864         page_remove_rmap(page, true);
2865         put_page(page);
2866
2867         mmu_notifier_invalidate_range_end(mm, address,
2868                         address + HPAGE_PMD_SIZE);
2869 }
2870
2871 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2872 {
2873         struct vm_area_struct *vma = pvmw->vma;
2874         struct mm_struct *mm = vma->vm_mm;
2875         unsigned long address = pvmw->address;
2876         unsigned long mmun_start = address & HPAGE_PMD_MASK;
2877         pmd_t pmde;
2878         swp_entry_t entry;
2879
2880         if (!(pvmw->pmd && !pvmw->pte))
2881                 return;
2882
2883         entry = pmd_to_swp_entry(*pvmw->pmd);
2884         get_page(new);
2885         pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2886         if (pmd_swp_soft_dirty(*pvmw->pmd))
2887                 pmde = pmd_mksoft_dirty(pmde);
2888         if (is_write_migration_entry(entry))
2889                 pmde = maybe_pmd_mkwrite(pmde, vma);
2890
2891         flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2892         page_add_anon_rmap(new, vma, mmun_start, true);
2893         set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2894         if (vma->vm_flags & VM_LOCKED)
2895                 mlock_vma_page(new);
2896         update_mmu_cache_pmd(vma, address, pvmw->pmd);
2897 }
2898 #endif