mm/madvise.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      linux/mm/madvise.c
   4  *
   5  * Copyright (C) 1999  Linus Torvalds
   6  * Copyright (C) 2002  Christoph Hellwig
   7  */
   8
   9 #include <linux/mman.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/syscalls.h>
  12 #include <linux/mempolicy.h>
  13 #include <linux/page-isolation.h>
  14 #include <linux/userfaultfd_k.h>
  15 #include <linux/hugetlb.h>
  16 #include <linux/falloc.h>
  17 #include <linux/fadvise.h>
  18 #include <linux/sched.h>
  19 #include <linux/ksm.h>
  20 #include <linux/fs.h>
  21 #include <linux/file.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/swap.h>
  25 #include <linux/swapops.h>
  26 #include <linux/shmem_fs.h>
  27 #include <linux/mmu_notifier.h>
  28
  29 #include <asm/tlb.h>
  30
  31 #include "internal.h"
  32
  33 /*
  34  * Any behaviour which results in changes to the vma->vm_flags needs to
  35  * take mmap_sem for writing. Others, which simply traverse vmas, need
  36  * to only take it for reading.
  37  */
  38 static int madvise_need_mmap_write(int behavior)
  39 {
  40         switch (behavior) {
  41         case MADV_REMOVE:
  42         case MADV_WILLNEED:
  43         case MADV_DONTNEED:
  44         case MADV_FREE:
  45                 return 0;
  46         default:
  47                 /* be safe, default to 1. list exceptions explicitly */
  48                 return 1;
  49         }
  50 }
  51
  52 /*
  53  * We can potentially split a vm area into separate
  54  * areas, each area with its own behavior.
  55  */
  56 static long madvise_behavior(struct vm_area_struct *vma,
  57                      struct vm_area_struct **prev,
  58                      unsigned long start, unsigned long end, int behavior)
  59 {
  60         struct mm_struct *mm = vma->vm_mm;
  61         int error = 0;
  62         pgoff_t pgoff;
  63         unsigned long new_flags = vma->vm_flags;
  64
  65         switch (behavior) {
  66         case MADV_NORMAL:
  67                 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
  68                 break;
  69         case MADV_SEQUENTIAL:
  70                 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
  71                 break;
  72         case MADV_RANDOM:
  73                 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
  74                 break;
  75         case MADV_DONTFORK:
  76                 new_flags |= VM_DONTCOPY;
  77                 break;
  78         case MADV_DOFORK:
  79                 if (vma->vm_flags & VM_IO) {
  80                         error = -EINVAL;
  81                         goto out;
  82                 }
  83                 new_flags &= ~VM_DONTCOPY;
  84                 break;
  85         case MADV_WIPEONFORK:
  86                 /* MADV_WIPEONFORK is only supported on anonymous memory. */
  87                 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
  88                         error = -EINVAL;
  89                         goto out;
  90                 }
  91                 new_flags |= VM_WIPEONFORK;
  92                 break;
  93         case MADV_KEEPONFORK:
  94                 new_flags &= ~VM_WIPEONFORK;
  95                 break;
  96         case MADV_DONTDUMP:
  97                 new_flags |= VM_DONTDUMP;
  98                 break;
  99         case MADV_DODUMP:
 100                 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) {
 101                         error = -EINVAL;
 102                         goto out;
 103                 }
 104                 new_flags &= ~VM_DONTDUMP;
 105                 break;
 106         case MADV_MERGEABLE:
 107         case MADV_UNMERGEABLE:
 108                 error = ksm_madvise(vma, start, end, behavior, &new_flags);
 109                 if (error) {
 110                         /*
 111                          * madvise() returns EAGAIN if kernel resources, such as
 112                          * slab, are temporarily unavailable.
 113                          */
 114                         if (error == -ENOMEM)
 115                                 error = -EAGAIN;
 116                         goto out;
 117                 }
 118                 break;
 119         case MADV_HUGEPAGE:
 120         case MADV_NOHUGEPAGE:
 121                 error = hugepage_madvise(vma, &new_flags, behavior);
 122                 if (error) {
 123                         /*
 124                          * madvise() returns EAGAIN if kernel resources, such as
 125                          * slab, are temporarily unavailable.
 126                          */
 127                         if (error == -ENOMEM)
 128                                 error = -EAGAIN;
 129                         goto out;
 130                 }
 131                 break;
 132         }
 133
 134         if (new_flags == vma->vm_flags) {
 135                 *prev = vma;
 136                 goto out;
 137         }
 138
 139         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 140         *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
 141                           vma->vm_file, pgoff, vma_policy(vma),
 142                           vma->vm_userfaultfd_ctx);
 143         if (*prev) {
 144                 vma = *prev;
 145                 goto success;
 146         }
 147
 148         *prev = vma;
 149
 150         if (start != vma->vm_start) {
 151                 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
 152                         error = -ENOMEM;
 153                         goto out;
 154                 }
 155                 error = __split_vma(mm, vma, start, 1);
 156                 if (error) {
 157                         /*
 158                          * madvise() returns EAGAIN if kernel resources, such as
 159                          * slab, are temporarily unavailable.
 160                          */
 161                         if (error == -ENOMEM)
 162                                 error = -EAGAIN;
 163                         goto out;
 164                 }
 165         }
 166
 167         if (end != vma->vm_end) {
 168                 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
 169                         error = -ENOMEM;
 170                         goto out;
 171                 }
 172                 error = __split_vma(mm, vma, end, 0);
 173                 if (error) {
 174                         /*
 175                          * madvise() returns EAGAIN if kernel resources, such as
 176                          * slab, are temporarily unavailable.
 177                          */
 178                         if (error == -ENOMEM)
 179                                 error = -EAGAIN;
 180                         goto out;
 181                 }
 182         }
 183
 184 success:
 185         /*
 186          * vm_flags is protected by the mmap_sem held in write mode.
 187          */
 188         vma->vm_flags = new_flags;
 189 out:
 190         return error;
 191 }
 192
 193 #ifdef CONFIG_SWAP
 194 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
 195         unsigned long end, struct mm_walk *walk)
 196 {
 197         pte_t *orig_pte;
 198         struct vm_area_struct *vma = walk->private;
 199         unsigned long index;
 200
 201         if (pmd_none_or_trans_huge_or_clear_bad(pmd))
 202                 return 0;
 203
 204         for (index = start; index != end; index += PAGE_SIZE) {
 205                 pte_t pte;
 206                 swp_entry_t entry;
 207                 struct page *page;
 208                 spinlock_t *ptl;
 209
 210                 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
 211                 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
 212                 pte_unmap_unlock(orig_pte, ptl);
 213
 214                 if (pte_present(pte) || pte_none(pte))
 215                         continue;
 216                 entry = pte_to_swp_entry(pte);
 217                 if (unlikely(non_swap_entry(entry)))
 218                         continue;
 219
 220                 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
 221                                                         vma, index, false);
 222                 if (page)
 223                         put_page(page);
 224         }
 225
 226         return 0;
 227 }
 228
 229 static void force_swapin_readahead(struct vm_area_struct *vma,
 230                 unsigned long start, unsigned long end)
 231 {
 232         struct mm_walk walk = {
 233                 .mm = vma->vm_mm,
 234                 .pmd_entry = swapin_walk_pmd_entry,
 235                 .private = vma,
 236         };
 237
 238         walk_page_range(start, end, &walk);
 239
 240         lru_add_drain();        /* Push any new pages onto the LRU now */
 241 }
 242
 243 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
 244                 unsigned long start, unsigned long end,
 245                 struct address_space *mapping)
 246 {
 247         pgoff_t index;
 248         struct page *page;
 249         swp_entry_t swap;
 250
 251         for (; start < end; start += PAGE_SIZE) {
 252                 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
 253
 254                 page = find_get_entry(mapping, index);
 255                 if (!xa_is_value(page)) {
 256                         if (page)
 257                                 put_page(page);
 258                         continue;
 259                 }
 260                 swap = radix_to_swp_entry(page);
 261                 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
 262                                                         NULL, 0, false);
 263                 if (page)
 264                         put_page(page);
 265         }
 266
 267         lru_add_drain();        /* Push any new pages onto the LRU now */
 268 }
 269 #endif          /* CONFIG_SWAP */
 270
 271 /*
 272  * Schedule all required I/O operations.  Do not wait for completion.
 273  */
 274 static long madvise_willneed(struct vm_area_struct *vma,
 275                              struct vm_area_struct **prev,
 276                              unsigned long start, unsigned long end)
 277 {
 278         struct file *file = vma->vm_file;
 279         loff_t offset;
 280
 281         *prev = vma;
 282 #ifdef CONFIG_SWAP
 283         if (!file) {
 284                 force_swapin_readahead(vma, start, end);
 285                 return 0;
 286         }
 287
 288         if (shmem_mapping(file->f_mapping)) {
 289                 force_shm_swapin_readahead(vma, start, end,
 290                                         file->f_mapping);
 291                 return 0;
 292         }
 293 #else
 294         if (!file)
 295                 return -EBADF;
 296 #endif
 297
 298         if (IS_DAX(file_inode(file))) {
 299                 /* no bad return value, but ignore advice */
 300                 return 0;
 301         }
 302
 303         /*
 304          * Filesystem's fadvise may need to take various locks.  We need to
 305          * explicitly grab a reference because the vma (and hence the
 306          * vma's reference to the file) can go away as soon as we drop
 307          * mmap_sem.
 308          */
 309         *prev = NULL;   /* tell sys_madvise we drop mmap_sem */
 310         get_file(file);
 311         up_read(&current->mm->mmap_sem);
 312         offset = (loff_t)(start - vma->vm_start)
 313                         + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 314         vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
 315         fput(file);
 316         down_read(&current->mm->mmap_sem);
 317         return 0;
 318 }
 319
 320 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 321                                 unsigned long end, struct mm_walk *walk)
 322
 323 {
 324         struct mmu_gather *tlb = walk->private;
 325         struct mm_struct *mm = tlb->mm;
 326         struct vm_area_struct *vma = walk->vma;
 327         spinlock_t *ptl;
 328         pte_t *orig_pte, *pte, ptent;
 329         struct page *page;
 330         int nr_swap = 0;
 331         unsigned long next;
 332
 333         next = pmd_addr_end(addr, end);
 334         if (pmd_trans_huge(*pmd))
 335                 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
 336                         goto next;
 337
 338         if (pmd_trans_unstable(pmd))
 339                 return 0;
 340
 341         tlb_change_page_size(tlb, PAGE_SIZE);
 342         orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 343         flush_tlb_batched_pending(mm);
 344         arch_enter_lazy_mmu_mode();
 345         for (; addr != end; pte++, addr += PAGE_SIZE) {
 346                 ptent = *pte;
 347
 348                 if (pte_none(ptent))
 349                         continue;
 350                 /*
 351                  * If the pte has swp_entry, just clear page table to
 352                  * prevent swap-in which is more expensive rather than
 353                  * (page allocation + zeroing).
 354                  */
 355                 if (!pte_present(ptent)) {
 356                         swp_entry_t entry;
 357
 358                         entry = pte_to_swp_entry(ptent);
 359                         if (non_swap_entry(entry))
 360                                 continue;
 361                         nr_swap--;
 362                         free_swap_and_cache(entry);
 363                         pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 364                         continue;
 365                 }
 366
 367                 page = vm_normal_page(vma, addr, ptent);
 368                 if (!page)
 369                         continue;
 370
 371                 /*
 372                  * If pmd isn't transhuge but the page is THP and
 373                  * is owned by only this process, split it and
 374                  * deactivate all pages.
 375                  */
 376                 if (PageTransCompound(page)) {
 377                         if (page_mapcount(page) != 1)
 378                                 goto out;
 379                         get_page(page);
 380                         if (!trylock_page(page)) {
 381                                 put_page(page);
 382                                 goto out;
 383                         }
 384                         pte_unmap_unlock(orig_pte, ptl);
 385                         if (split_huge_page(page)) {
 386                                 unlock_page(page);
 387                                 put_page(page);
 388                                 pte_offset_map_lock(mm, pmd, addr, &ptl);
 389                                 goto out;
 390                         }
 391                         unlock_page(page);
 392                         put_page(page);
 393                         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 394                         pte--;
 395                         addr -= PAGE_SIZE;
 396                         continue;
 397                 }
 398
 399                 VM_BUG_ON_PAGE(PageTransCompound(page), page);
 400
 401                 if (PageSwapCache(page) || PageDirty(page)) {
 402                         if (!trylock_page(page))
 403                                 continue;
 404                         /*
 405                          * If page is shared with others, we couldn't clear
 406                          * PG_dirty of the page.
 407                          */
 408                         if (page_mapcount(page) != 1) {
 409                                 unlock_page(page);
 410                                 continue;
 411                         }
 412
 413                         if (PageSwapCache(page) && !try_to_free_swap(page)) {
 414                                 unlock_page(page);
 415                                 continue;
 416                         }
 417
 418                         ClearPageDirty(page);
 419                         unlock_page(page);
 420                 }
 421
 422                 if (pte_young(ptent) || pte_dirty(ptent)) {
 423                         /*
 424                          * Some of architecture(ex, PPC) don't update TLB
 425                          * with set_pte_at and tlb_remove_tlb_entry so for
 426                          * the portability, remap the pte with old|clean
 427                          * after pte clearing.
 428                          */
 429                         ptent = ptep_get_and_clear_full(mm, addr, pte,
 430                                                         tlb->fullmm);
 431
 432                         ptent = pte_mkold(ptent);
 433                         ptent = pte_mkclean(ptent);
 434                         set_pte_at(mm, addr, pte, ptent);
 435                         tlb_remove_tlb_entry(tlb, pte, addr);
 436                 }
 437                 mark_page_lazyfree(page);
 438         }
 439 out:
 440         if (nr_swap) {
 441                 if (current->mm == mm)
 442                         sync_mm_rss(mm);
 443
 444                 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
 445         }
 446         arch_leave_lazy_mmu_mode();
 447         pte_unmap_unlock(orig_pte, ptl);
 448         cond_resched();
 449 next:
 450         return 0;
 451 }
 452
 453 static void madvise_free_page_range(struct mmu_gather *tlb,
 454                              struct vm_area_struct *vma,
 455                              unsigned long addr, unsigned long end)
 456 {
 457         struct mm_walk free_walk = {
 458                 .pmd_entry = madvise_free_pte_range,
 459                 .mm = vma->vm_mm,
 460                 .private = tlb,
 461         };
 462
 463         tlb_start_vma(tlb, vma);
 464         walk_page_range(addr, end, &free_walk);
 465         tlb_end_vma(tlb, vma);
 466 }
 467
 468 static int madvise_free_single_vma(struct vm_area_struct *vma,
 469                         unsigned long start_addr, unsigned long end_addr)
 470 {
 471         struct mm_struct *mm = vma->vm_mm;
 472         struct mmu_notifier_range range;
 473         struct mmu_gather tlb;
 474
 475         /* MADV_FREE works for only anon vma at the moment */
 476         if (!vma_is_anonymous(vma))
 477                 return -EINVAL;
 478
 479         range.start = max(vma->vm_start, start_addr);
 480         if (range.start >= vma->vm_end)
 481                 return -EINVAL;
 482         range.end = min(vma->vm_end, end_addr);
 483         if (range.end <= vma->vm_start)
 484                 return -EINVAL;
 485         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
 486                                 range.start, range.end);
 487
 488         lru_add_drain();
 489         tlb_gather_mmu(&tlb, mm, range.start, range.end);
 490         update_hiwater_rss(mm);
 491
 492         mmu_notifier_invalidate_range_start(&range);
 493         madvise_free_page_range(&tlb, vma, range.start, range.end);
 494         mmu_notifier_invalidate_range_end(&range);
 495         tlb_finish_mmu(&tlb, range.start, range.end);
 496
 497         return 0;
 498 }
 499
 500 /*
 501  * Application no longer needs these pages.  If the pages are dirty,
 502  * it's OK to just throw them away.  The app will be more careful about
 503  * data it wants to keep.  Be sure to free swap resources too.  The
 504  * zap_page_range call sets things up for shrink_active_list to actually free
 505  * these pages later if no one else has touched them in the meantime,
 506  * although we could add these pages to a global reuse list for
 507  * shrink_active_list to pick up before reclaiming other pages.
 508  *
 509  * NB: This interface discards data rather than pushes it out to swap,
 510  * as some implementations do.  This has performance implications for
 511  * applications like large transactional databases which want to discard
 512  * pages in anonymous maps after committing to backing store the data
 513  * that was kept in them.  There is no reason to write this data out to
 514  * the swap area if the application is discarding it.
 515  *
 516  * An interface that causes the system to free clean pages and flush
 517  * dirty pages is already available as msync(MS_INVALIDATE).
 518  */
 519 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
 520                                         unsigned long start, unsigned long end)
 521 {
 522         zap_page_range(vma, start, end - start);
 523         return 0;
 524 }
 525
 526 static long madvise_dontneed_free(struct vm_area_struct *vma,
 527                                   struct vm_area_struct **prev,
 528                                   unsigned long start, unsigned long end,
 529                                   int behavior)
 530 {
 531         *prev = vma;
 532         if (!can_madv_dontneed_vma(vma))
 533                 return -EINVAL;
 534
 535         if (!userfaultfd_remove(vma, start, end)) {
 536                 *prev = NULL; /* mmap_sem has been dropped, prev is stale */
 537
 538                 down_read(&current->mm->mmap_sem);
 539                 vma = find_vma(current->mm, start);
 540                 if (!vma)
 541                         return -ENOMEM;
 542                 if (start < vma->vm_start) {
 543                         /*
 544                          * This "vma" under revalidation is the one
 545                          * with the lowest vma->vm_start where start
 546                          * is also < vma->vm_end. If start <
 547                          * vma->vm_start it means an hole materialized
 548                          * in the user address space within the
 549                          * virtual range passed to MADV_DONTNEED
 550                          * or MADV_FREE.
 551                          */
 552                         return -ENOMEM;
 553                 }
 554                 if (!can_madv_dontneed_vma(vma))
 555                         return -EINVAL;
 556                 if (end > vma->vm_end) {
 557                         /*
 558                          * Don't fail if end > vma->vm_end. If the old
 559                          * vma was splitted while the mmap_sem was
 560                          * released the effect of the concurrent
 561                          * operation may not cause madvise() to
 562                          * have an undefined result. There may be an
 563                          * adjacent next vma that we'll walk
 564                          * next. userfaultfd_remove() will generate an
 565                          * UFFD_EVENT_REMOVE repetition on the
 566                          * end-vma->vm_end range, but the manager can
 567                          * handle a repetition fine.
 568                          */
 569                         end = vma->vm_end;
 570                 }
 571                 VM_WARN_ON(start >= end);
 572         }
 573
 574         if (behavior == MADV_DONTNEED)
 575                 return madvise_dontneed_single_vma(vma, start, end);
 576         else if (behavior == MADV_FREE)
 577                 return madvise_free_single_vma(vma, start, end);
 578         else
 579                 return -EINVAL;
 580 }
 581
 582 /*
 583  * Application wants to free up the pages and associated backing store.
 584  * This is effectively punching a hole into the middle of a file.
 585  */
 586 static long madvise_remove(struct vm_area_struct *vma,
 587                                 struct vm_area_struct **prev,
 588                                 unsigned long start, unsigned long end)
 589 {
 590         loff_t offset;
 591         int error;
 592         struct file *f;
 593
 594         *prev = NULL;   /* tell sys_madvise we drop mmap_sem */
 595
 596         if (vma->vm_flags & VM_LOCKED)
 597                 return -EINVAL;
 598
 599         f = vma->vm_file;
 600
 601         if (!f || !f->f_mapping || !f->f_mapping->host) {
 602                         return -EINVAL;
 603         }
 604
 605         if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
 606                 return -EACCES;
 607
 608         offset = (loff_t)(start - vma->vm_start)
 609                         + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 610
 611         /*
 612          * Filesystem's fallocate may need to take i_mutex.  We need to
 613          * explicitly grab a reference because the vma (and hence the
 614          * vma's reference to the file) can go away as soon as we drop
 615          * mmap_sem.
 616          */
 617         get_file(f);
 618         if (userfaultfd_remove(vma, start, end)) {
 619                 /* mmap_sem was not released by userfaultfd_remove() */
 620                 up_read(&current->mm->mmap_sem);
 621         }
 622         error = vfs_fallocate(f,
 623                                 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 624                                 offset, end - start);
 625         fput(f);
 626         down_read(&current->mm->mmap_sem);
 627         return error;
 628 }
 629
 630 #ifdef CONFIG_MEMORY_FAILURE
 631 /*
 632  * Error injection support for memory error handling.
 633  */
 634 static int madvise_inject_error(int behavior,
 635                 unsigned long start, unsigned long end)
 636 {
 637         struct page *page;
 638         struct zone *zone;
 639         unsigned int order;
 640
 641         if (!capable(CAP_SYS_ADMIN))
 642                 return -EPERM;
 643
 644
 645         for (; start < end; start += PAGE_SIZE << order) {
 646                 unsigned long pfn;
 647                 int ret;
 648
 649                 ret = get_user_pages_fast(start, 1, 0, &page);
 650                 if (ret != 1)
 651                         return ret;
 652                 pfn = page_to_pfn(page);
 653
 654                 /*
 655                  * When soft offlining hugepages, after migrating the page
 656                  * we dissolve it, therefore in the second loop "page" will
 657                  * no longer be a compound page, and order will be 0.
 658                  */
 659                 order = compound_order(compound_head(page));
 660
 661                 if (PageHWPoison(page)) {
 662                         put_page(page);
 663                         continue;
 664                 }
 665
 666                 if (behavior == MADV_SOFT_OFFLINE) {
 667                         pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
 668                                         pfn, start);
 669
 670                         ret = soft_offline_page(page, MF_COUNT_INCREASED);
 671                         if (ret)
 672                                 return ret;
 673                         continue;
 674                 }
 675
 676                 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
 677                                 pfn, start);
 678
 679                 /*
 680                  * Drop the page reference taken by get_user_pages_fast(). In
 681                  * the absence of MF_COUNT_INCREASED the memory_failure()
 682                  * routine is responsible for pinning the page to prevent it
 683                  * from being released back to the page allocator.
 684                  */
 685                 put_page(page);
 686                 ret = memory_failure(pfn, 0);
 687                 if (ret)
 688                         return ret;
 689         }
 690
 691         /* Ensure that all poisoned pages are removed from per-cpu lists */
 692         for_each_populated_zone(zone)
 693                 drain_all_pages(zone);
 694
 695         return 0;
 696 }
 697 #endif
 698
 699 static long
 700 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
 701                 unsigned long start, unsigned long end, int behavior)
 702 {
 703         switch (behavior) {
 704         case MADV_REMOVE:
 705                 return madvise_remove(vma, prev, start, end);
 706         case MADV_WILLNEED:
 707                 return madvise_willneed(vma, prev, start, end);
 708         case MADV_FREE:
 709         case MADV_DONTNEED:
 710                 return madvise_dontneed_free(vma, prev, start, end, behavior);
 711         default:
 712                 return madvise_behavior(vma, prev, start, end, behavior);
 713         }
 714 }
 715
 716 static bool
 717 madvise_behavior_valid(int behavior)
 718 {
 719         switch (behavior) {
 720         case MADV_DOFORK:
 721         case MADV_DONTFORK:
 722         case MADV_NORMAL:
 723         case MADV_SEQUENTIAL:
 724         case MADV_RANDOM:
 725         case MADV_REMOVE:
 726         case MADV_WILLNEED:
 727         case MADV_DONTNEED:
 728         case MADV_FREE:
 729 #ifdef CONFIG_KSM
 730         case MADV_MERGEABLE:
 731         case MADV_UNMERGEABLE:
 732 #endif
 733 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 734         case MADV_HUGEPAGE:
 735         case MADV_NOHUGEPAGE:
 736 #endif
 737         case MADV_DONTDUMP:
 738         case MADV_DODUMP:
 739         case MADV_WIPEONFORK:
 740         case MADV_KEEPONFORK:
 741 #ifdef CONFIG_MEMORY_FAILURE
 742         case MADV_SOFT_OFFLINE:
 743         case MADV_HWPOISON:
 744 #endif
 745                 return true;
 746
 747         default:
 748                 return false;
 749         }
 750 }
 751
 752 /*
 753  * The madvise(2) system call.
 754  *
 755  * Applications can use madvise() to advise the kernel how it should
 756  * handle paging I/O in this VM area.  The idea is to help the kernel
 757  * use appropriate read-ahead and caching techniques.  The information
 758  * provided is advisory only, and can be safely disregarded by the
 759  * kernel without affecting the correct operation of the application.
 760  *
 761  * behavior values:
 762  *  MADV_NORMAL - the default behavior is to read clusters.  This
 763  *              results in some read-ahead and read-behind.
 764  *  MADV_RANDOM - the system should read the minimum amount of data
 765  *              on any access, since it is unlikely that the appli-
 766  *              cation will need more than what it asks for.
 767  *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
 768  *              once, so they can be aggressively read ahead, and
 769  *              can be freed soon after they are accessed.
 770  *  MADV_WILLNEED - the application is notifying the system to read
 771  *              some pages ahead.
 772  *  MADV_DONTNEED - the application is finished with the given range,
 773  *              so the kernel can free resources associated with it.
 774  *  MADV_FREE - the application marks pages in the given range as lazy free,
 775  *              where actual purges are postponed until memory pressure happens.
 776  *  MADV_REMOVE - the application wants to free up the given range of
 777  *              pages and associated backing store.
 778  *  MADV_DONTFORK - omit this area from child's address space when forking:
 779  *              typically, to avoid COWing pages pinned by get_user_pages().
 780  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
 781  *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
 782  *              range after a fork.
 783  *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
 784  *  MADV_HWPOISON - trigger memory error handler as if the given memory range
 785  *              were corrupted by unrecoverable hardware memory failure.
 786  *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
 787  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
 788  *              this area with pages of identical content from other such areas.
 789  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
 790  *  MADV_HUGEPAGE - the application wants to back the given range by transparent
 791  *              huge pages in the future. Existing pages might be coalesced and
 792  *              new pages might be allocated as THP.
 793  *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
 794  *              transparent huge pages so the existing pages will not be
 795  *              coalesced into THP and new pages will not be allocated as THP.
 796  *  MADV_DONTDUMP - the application wants to prevent pages in the given range
 797  *              from being included in its core dump.
 798  *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
 799  *
 800  * return values:
 801  *  zero    - success
 802  *  -EINVAL - start + len < 0, start is not page-aligned,
 803  *              "behavior" is not a valid value, or application
 804  *              is attempting to release locked or shared pages,
 805  *              or the specified address range includes file, Huge TLB,
 806  *              MAP_SHARED or VMPFNMAP range.
 807  *  -ENOMEM - addresses in the specified range are not currently
 808  *              mapped, or are outside the AS of the process.
 809  *  -EIO    - an I/O error occurred while paging in data.
 810  *  -EBADF  - map exists, but area maps something that isn't a file.
 811  *  -EAGAIN - a kernel resource was temporarily unavailable.
 812  */
 813 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
 814 {
 815         unsigned long end, tmp;
 816         struct vm_area_struct *vma, *prev;
 817         int unmapped_error = 0;
 818         int error = -EINVAL;
 819         int write;
 820         size_t len;
 821         struct blk_plug plug;
 822
 823         if (!madvise_behavior_valid(behavior))
 824                 return error;
 825
 826         if (start & ~PAGE_MASK)
 827                 return error;
 828         len = (len_in + ~PAGE_MASK) & PAGE_MASK;
 829
 830         /* Check to see whether len was rounded up from small -ve to zero */
 831         if (len_in && !len)
 832                 return error;
 833
 834         end = start + len;
 835         if (end < start)
 836                 return error;
 837
 838         error = 0;
 839         if (end == start)
 840                 return error;
 841
 842 #ifdef CONFIG_MEMORY_FAILURE
 843         if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
 844                 return madvise_inject_error(behavior, start, start + len_in);
 845 #endif
 846
 847         write = madvise_need_mmap_write(behavior);
 848         if (write) {
 849                 if (down_write_killable(&current->mm->mmap_sem))
 850                         return -EINTR;
 851         } else {
 852                 down_read(&current->mm->mmap_sem);
 853         }
 854
 855         /*
 856          * If the interval [start,end) covers some unmapped address
 857          * ranges, just ignore them, but return -ENOMEM at the end.
 858          * - different from the way of handling in mlock etc.
 859          */
 860         vma = find_vma_prev(current->mm, start, &prev);
 861         if (vma && start > vma->vm_start)
 862                 prev = vma;
 863
 864         blk_start_plug(&plug);
 865         for (;;) {
 866                 /* Still start < end. */
 867                 error = -ENOMEM;
 868                 if (!vma)
 869                         goto out;
 870
 871                 /* Here start < (end|vma->vm_end). */
 872                 if (start < vma->vm_start) {
 873                         unmapped_error = -ENOMEM;
 874                         start = vma->vm_start;
 875                         if (start >= end)
 876                                 goto out;
 877                 }
 878
 879                 /* Here vma->vm_start <= start < (end|vma->vm_end) */
 880                 tmp = vma->vm_end;
 881                 if (end < tmp)
 882                         tmp = end;
 883
 884                 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
 885                 error = madvise_vma(vma, &prev, start, tmp, behavior);
 886                 if (error)
 887                         goto out;
 888                 start = tmp;
 889                 if (prev && start < prev->vm_end)
 890                         start = prev->vm_end;
 891                 error = unmapped_error;
 892                 if (start >= end)
 893                         goto out;
 894                 if (prev)
 895                         vma = prev->vm_next;
 896                 else    /* madvise_remove dropped mmap_sem */
 897                         vma = find_vma(current->mm, start);
 898         }
 899 out:
 900         blk_finish_plug(&plug);
 901         if (write)
 902                 up_write(&current->mm->mmap_sem);
 903         else
 904                 up_read(&current->mm->mmap_sem);
 905
 906         return error;
 907 }