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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  linux/mm/madvise.c
  *
  * Copyright (C) 1999  Linus Torvalds
  * Copyright (C) 2002  Christoph Hellwig
  */
 
 #include <linux/mman.h>
 #include <linux/pagemap.h>
 #include <linux/syscalls.h>
 #include <linux/mempolicy.h>
 #include <linux/page-isolation.h>
 #include <linux/page_idle.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/hugetlb.h>
 #include <linux/falloc.h>
 #include <linux/fadvise.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
 #include <linux/mm_inline.h>
 #include <linux/string.h>
 #include <linux/uio.h>
 #include <linux/ksm.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/pagewalk.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
 #include <linux/shmem_fs.h>
 #include <linux/mmu_notifier.h>
 
 #include <asm/tlb.h>
 
 #include "internal.h"
 #include "swap.h"
 
 struct madvise_walk_private {
     struct mmu_gather *tlb;
     bool pageout;
 };
 
 /*
  * Any behaviour which results in changes to the vma->vm_flags needs to
  * take mmap_lock for writing. Others, which simply traverse vmas, need
  * to only take it for reading.
  */
 static int madvise_need_mmap_write(int behavior)
 {
     switch (behavior) {
     case MADV_REMOVE:
     case MADV_WILLNEED:
     case MADV_DONTNEED:
     case MADV_DONTNEED_LOCKED:
     case MADV_COLD:
     case MADV_PAGEOUT:
     case MADV_FREE:
     case MADV_POPULATE_READ:
     case MADV_POPULATE_WRITE:
         return 0;
     default:
         /* be safe, default to 1. list exceptions explicitly */
         return 1;
     }
 }
 
 #ifdef CONFIG_ANON_VMA_NAME
 struct anon_vma_name *anon_vma_name_alloc(const char *name)
 {
     struct anon_vma_name *anon_name;
     size_t count;
 
     /* Add 1 for NUL terminator at the end of the anon_name->name */
     count = strlen(name) + 1;
     anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
     if (anon_name) {
         kref_init(&anon_name->kref);
         memcpy(anon_name->name, name, count);
     }
 
     return anon_name;
 }
 
 void anon_vma_name_free(struct kref *kref)
 {
     struct anon_vma_name *anon_name =
             container_of(kref, struct anon_vma_name, kref);
     kfree(anon_name);
 }
 
 struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
 {
     mmap_assert_locked(vma->vm_mm);
 
     if (vma->vm_file)
         return NULL;
 
     return vma->anon_name;
 }
 
 /* mmap_lock should be write-locked */
 static int replace_anon_vma_name(struct vm_area_struct *vma,
                  struct anon_vma_name *anon_name)
 {
     struct anon_vma_name *orig_name = anon_vma_name(vma);
 
     if (!anon_name) {
         vma->anon_name = NULL;
         anon_vma_name_put(orig_name);
         return 0;
     }
 
     if (anon_vma_name_eq(orig_name, anon_name))
         return 0;
 
     vma->anon_name = anon_vma_name_reuse(anon_name);
     anon_vma_name_put(orig_name);
 
     return 0;
 }
 #else /* CONFIG_ANON_VMA_NAME */
 static int replace_anon_vma_name(struct vm_area_struct *vma,
                  struct anon_vma_name *anon_name)
 {
     if (anon_name)
         return -EINVAL;
 
     return 0;
 }
 #endif /* CONFIG_ANON_VMA_NAME */
 /*
  * Update the vm_flags on region of a vma, splitting it or merging it as
  * necessary.  Must be called with mmap_sem held for writing;
  * Caller should ensure anon_name stability by raising its refcount even when
  * anon_name belongs to a valid vma because this function might free that vma.
  */
 static int madvise_update_vma(struct vm_area_struct *vma,
                   struct vm_area_struct **prev, unsigned long start,
                   unsigned long end, unsigned long new_flags,
                   struct anon_vma_name *anon_name)
 {
     struct mm_struct *mm = vma->vm_mm;
     int error;
     pgoff_t pgoff;
 
     if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
         *prev = vma;
         return 0;
     }
 
     pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
     *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
               vma->vm_file, pgoff, vma_policy(vma),
               vma->vm_userfaultfd_ctx, anon_name);
     if (*prev) {
         vma = *prev;
         goto success;
     }
 
     *prev = vma;
 
     if (start != vma->vm_start) {
         if (unlikely(mm->map_count >= sysctl_max_map_count))
             return -ENOMEM;
         error = __split_vma(mm, vma, start, 1);
         if (error)
             return error;
     }
 
     if (end != vma->vm_end) {
         if (unlikely(mm->map_count >= sysctl_max_map_count))
             return -ENOMEM;
         error = __split_vma(mm, vma, end, 0);
         if (error)
             return error;
     }
 
 success:
     /*
      * vm_flags is protected by the mmap_lock held in write mode.
      */
     vma->vm_flags = new_flags;
     if (!vma->vm_file) {
         error = replace_anon_vma_name(vma, anon_name);
         if (error)
             return error;
     }
 
     return 0;
 }
 
 #ifdef CONFIG_SWAP
 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
     unsigned long end, struct mm_walk *walk)
 {
     struct vm_area_struct *vma = walk->private;
     unsigned long index;
     struct swap_iocb *splug = NULL;
 
     if (pmd_none_or_trans_huge_or_clear_bad(pmd))
         return 0;
 
     for (index = start; index != end; index += PAGE_SIZE) {
         pte_t pte;
         swp_entry_t entry;
         struct page *page;
         spinlock_t *ptl;
         pte_t *ptep;
 
         ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
         pte = *ptep;
         pte_unmap_unlock(ptep, ptl);
 
         if (!is_swap_pte(pte))
             continue;
         entry = pte_to_swp_entry(pte);
         if (unlikely(non_swap_entry(entry)))
             continue;
 
         page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
                          vma, index, false, &splug);
         if (page)
             put_page(page);
     }
     swap_read_unplug(splug);
 
     return 0;
 }
 
 static const struct mm_walk_ops swapin_walk_ops = {
     .pmd_entry      = swapin_walk_pmd_entry,
 };
 
 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
         unsigned long start, unsigned long end,
         struct address_space *mapping)
 {
     XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
     pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
     struct page *page;
     struct swap_iocb *splug = NULL;
 
     rcu_read_lock();
     xas_for_each(&xas, page, end_index) {
         swp_entry_t swap;
 
         if (!xa_is_value(page))
             continue;
         swap = radix_to_swp_entry(page);
         /* There might be swapin error entries in shmem mapping. */
         if (non_swap_entry(swap))
             continue;
         xas_pause(&xas);
         rcu_read_unlock();
 
         page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
                          NULL, 0, false, &splug);
         if (page)
             put_page(page);
 
         rcu_read_lock();
     }
     rcu_read_unlock();
     swap_read_unplug(splug);
 
     lru_add_drain();    /* Push any new pages onto the LRU now */
 }
 #endif      /* CONFIG_SWAP */
 
 /*
  * Schedule all required I/O operations.  Do not wait for completion.
  */
 static long madvise_willneed(struct vm_area_struct *vma,
                  struct vm_area_struct **prev,
                  unsigned long start, unsigned long end)
 {
     struct mm_struct *mm = vma->vm_mm;
     struct file *file = vma->vm_file;
     loff_t offset;
 
     *prev = vma;
 #ifdef CONFIG_SWAP
     if (!file) {
         walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
         lru_add_drain(); /* Push any new pages onto the LRU now */
         return 0;
     }
 
     if (shmem_mapping(file->f_mapping)) {
         force_shm_swapin_readahead(vma, start, end,
                     file->f_mapping);
         return 0;
     }
 #else
     if (!file)
         return -EBADF;
 #endif
 
     if (IS_DAX(file_inode(file))) {
         /* no bad return value, but ignore advice */
         return 0;
     }
 
     /*
      * Filesystem's fadvise may need to take various locks.  We need to
      * explicitly grab a reference because the vma (and hence the
      * vma's reference to the file) can go away as soon as we drop
      * mmap_lock.
      */
     *prev = NULL;   /* tell sys_madvise we drop mmap_lock */
     get_file(file);
     offset = (loff_t)(start - vma->vm_start)
             + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
     mmap_read_unlock(mm);
     vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
     fput(file);
     mmap_read_lock(mm);
     return 0;
 }
 
 static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
                 unsigned long addr, unsigned long end,
                 struct mm_walk *walk)
 {
     struct madvise_walk_private *private = walk->private;
     struct mmu_gather *tlb = private->tlb;
     bool pageout = private->pageout;
     struct mm_struct *mm = tlb->mm;
     struct vm_area_struct *vma = walk->vma;
     pte_t *orig_pte, *pte, ptent;
     spinlock_t *ptl;
     struct page *page = NULL;
     LIST_HEAD(page_list);
 
     if (fatal_signal_pending(current))
         return -EINTR;
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
     if (pmd_trans_huge(*pmd)) {
         pmd_t orig_pmd;
         unsigned long next = pmd_addr_end(addr, end);
 
         tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
         ptl = pmd_trans_huge_lock(pmd, vma);
         if (!ptl)
             return 0;
 
         orig_pmd = *pmd;
         if (is_huge_zero_pmd(orig_pmd))
             goto huge_unlock;
 
         if (unlikely(!pmd_present(orig_pmd))) {
             VM_BUG_ON(thp_migration_supported() &&
                     !is_pmd_migration_entry(orig_pmd));
             goto huge_unlock;
         }
 
         page = pmd_page(orig_pmd);
 
         /* Do not interfere with other mappings of this page */
         if (page_mapcount(page) != 1)
             goto huge_unlock;
 
         if (next - addr != HPAGE_PMD_SIZE) {
             int err;
 
             get_page(page);
             spin_unlock(ptl);
             lock_page(page);
             err = split_huge_page(page);
             unlock_page(page);
             put_page(page);
             if (!err)
                 goto regular_page;
             return 0;
         }
 
         if (pmd_young(orig_pmd)) {
             pmdp_invalidate(vma, addr, pmd);
             orig_pmd = pmd_mkold(orig_pmd);
 
             set_pmd_at(mm, addr, pmd, orig_pmd);
             tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
         }
 
         ClearPageReferenced(page);
         test_and_clear_page_young(page);
         if (pageout) {
             if (!isolate_lru_page(page)) {
                 if (PageUnevictable(page))
                     putback_lru_page(page);
                 else
                     list_add(&page->lru, &page_list);
             }
         } else
             deactivate_page(page);
 huge_unlock:
         spin_unlock(ptl);
         if (pageout)
             reclaim_pages(&page_list);
         return 0;
     }
 
 regular_page:
     if (pmd_trans_unstable(pmd))
         return 0;
 #endif
     tlb_change_page_size(tlb, PAGE_SIZE);
     orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
     flush_tlb_batched_pending(mm);
     arch_enter_lazy_mmu_mode();
     for (; addr < end; pte++, addr += PAGE_SIZE) {
         ptent = *pte;
 
         if (pte_none(ptent))
             continue;
 
         if (!pte_present(ptent))
             continue;
 
         page = vm_normal_page(vma, addr, ptent);
         if (!page || is_zone_device_page(page))
             continue;
 
         /*
          * Creating a THP page is expensive so split it only if we
          * are sure it's worth. Split it if we are only owner.
          */
         if (PageTransCompound(page)) {
             if (page_mapcount(page) != 1)
                 break;
             get_page(page);
             if (!trylock_page(page)) {
                 put_page(page);
                 break;
             }
             pte_unmap_unlock(orig_pte, ptl);
             if (split_huge_page(page)) {
                 unlock_page(page);
                 put_page(page);
                 orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
                 break;
             }
             unlock_page(page);
             put_page(page);
             orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
             pte--;
             addr -= PAGE_SIZE;
             continue;
         }
 
         /*
          * Do not interfere with other mappings of this page and
          * non-LRU page.
          */
         if (!PageLRU(page) || page_mapcount(page) != 1)
             continue;
 
         VM_BUG_ON_PAGE(PageTransCompound(page), page);
 
         if (pte_young(ptent)) {
             ptent = ptep_get_and_clear_full(mm, addr, pte,
                             tlb->fullmm);
             ptent = pte_mkold(ptent);
             set_pte_at(mm, addr, pte, ptent);
             tlb_remove_tlb_entry(tlb, pte, addr);
         }
 
         /*
          * We are deactivating a page for accelerating reclaiming.
          * VM couldn't reclaim the page unless we clear PG_young.
          * As a side effect, it makes confuse idle-page tracking
          * because they will miss recent referenced history.
          */
         ClearPageReferenced(page);
         test_and_clear_page_young(page);
         if (pageout) {
             if (!isolate_lru_page(page)) {
                 if (PageUnevictable(page))
                     putback_lru_page(page);
                 else
                     list_add(&page->lru, &page_list);
             }
         } else
             deactivate_page(page);
     }
 
     arch_leave_lazy_mmu_mode();
     pte_unmap_unlock(orig_pte, ptl);
     if (pageout)
         reclaim_pages(&page_list);
     cond_resched();
 
     return 0;
 }
 
 static const struct mm_walk_ops cold_walk_ops = {
     .pmd_entry = madvise_cold_or_pageout_pte_range,
 };
 
 static void madvise_cold_page_range(struct mmu_gather *tlb,
                  struct vm_area_struct *vma,
                  unsigned long addr, unsigned long end)
 {
     struct madvise_walk_private walk_private = {
         .pageout = false,
         .tlb = tlb,
     };
 
     tlb_start_vma(tlb, vma);
     walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
     tlb_end_vma(tlb, vma);
 }
 
 static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
 {
     return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
 }
 
 static long madvise_cold(struct vm_area_struct *vma,
             struct vm_area_struct **prev,
             unsigned long start_addr, unsigned long end_addr)
 {
     struct mm_struct *mm = vma->vm_mm;
     struct mmu_gather tlb;
 
     *prev = vma;
     if (!can_madv_lru_vma(vma))
         return -EINVAL;
 
     lru_add_drain();
     tlb_gather_mmu(&tlb, mm);
     madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
     tlb_finish_mmu(&tlb);
 
     return 0;
 }
 
 static void madvise_pageout_page_range(struct mmu_gather *tlb,
                  struct vm_area_struct *vma,
                  unsigned long addr, unsigned long end)
 {
     struct madvise_walk_private walk_private = {
         .pageout = true,
         .tlb = tlb,
     };
 
     tlb_start_vma(tlb, vma);
     walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
     tlb_end_vma(tlb, vma);
 }
 
 static inline bool can_do_pageout(struct vm_area_struct *vma)
 {
     if (vma_is_anonymous(vma))
         return true;
     if (!vma->vm_file)
         return false;
     /*
      * paging out pagecache only for non-anonymous mappings that correspond
      * to the files the calling process could (if tried) open for writing;
      * otherwise we'd be including shared non-exclusive mappings, which
      * opens a side channel.
      */
     return inode_owner_or_capable(&init_user_ns,
                       file_inode(vma->vm_file)) ||
            file_permission(vma->vm_file, MAY_WRITE) == 0;
 }
 
 static long madvise_pageout(struct vm_area_struct *vma,
             struct vm_area_struct **prev,
             unsigned long start_addr, unsigned long end_addr)
 {
     struct mm_struct *mm = vma->vm_mm;
     struct mmu_gather tlb;
 
     *prev = vma;
     if (!can_madv_lru_vma(vma))
         return -EINVAL;
 
     if (!can_do_pageout(vma))
         return 0;
 
     lru_add_drain();
     tlb_gather_mmu(&tlb, mm);
     madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
     tlb_finish_mmu(&tlb);
 
     return 0;
 }
 
 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
                 unsigned long end, struct mm_walk *walk)
 
 {
     struct mmu_gather *tlb = walk->private;
     struct mm_struct *mm = tlb->mm;
     struct vm_area_struct *vma = walk->vma;
     spinlock_t *ptl;
     pte_t *orig_pte, *pte, ptent;
     struct page *page;
     int nr_swap = 0;
     unsigned long next;
 
     next = pmd_addr_end(addr, end);
     if (pmd_trans_huge(*pmd))
         if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
             goto next;
 
     if (pmd_trans_unstable(pmd))
         return 0;
 
     tlb_change_page_size(tlb, PAGE_SIZE);
     orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
     flush_tlb_batched_pending(mm);
     arch_enter_lazy_mmu_mode();
     for (; addr != end; pte++, addr += PAGE_SIZE) {
         ptent = *pte;
 
         if (pte_none(ptent))
             continue;
         /*
          * If the pte has swp_entry, just clear page table to
          * prevent swap-in which is more expensive rather than
          * (page allocation + zeroing).
          */
         if (!pte_present(ptent)) {
             swp_entry_t entry;
 
             entry = pte_to_swp_entry(ptent);
             if (!non_swap_entry(entry)) {
                 nr_swap--;
                 free_swap_and_cache(entry);
                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
             } else if (is_hwpoison_entry(entry) ||
                    is_swapin_error_entry(entry)) {
                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
             }
             continue;
         }
 
         page = vm_normal_page(vma, addr, ptent);
         if (!page || is_zone_device_page(page))
             continue;
 
         /*
          * If pmd isn't transhuge but the page is THP and
          * is owned by only this process, split it and
          * deactivate all pages.
          */
         if (PageTransCompound(page)) {
             if (page_mapcount(page) != 1)
                 goto out;
             get_page(page);
             if (!trylock_page(page)) {
                 put_page(page);
                 goto out;
             }
             pte_unmap_unlock(orig_pte, ptl);
             if (split_huge_page(page)) {
                 unlock_page(page);
                 put_page(page);
                 orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
                 goto out;
             }
             unlock_page(page);
             put_page(page);
             orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
             pte--;
             addr -= PAGE_SIZE;
             continue;
         }
 
         VM_BUG_ON_PAGE(PageTransCompound(page), page);
 
         if (PageSwapCache(page) || PageDirty(page)) {
             if (!trylock_page(page))
                 continue;
             /*
              * If page is shared with others, we couldn't clear
              * PG_dirty of the page.
              */
             if (page_mapcount(page) != 1) {
                 unlock_page(page);
                 continue;
             }
 
             if (PageSwapCache(page) && !try_to_free_swap(page)) {
                 unlock_page(page);
                 continue;
             }
 
             ClearPageDirty(page);
             unlock_page(page);
         }
 
         if (pte_young(ptent) || pte_dirty(ptent)) {
             /*
              * Some of architecture(ex, PPC) don't update TLB
              * with set_pte_at and tlb_remove_tlb_entry so for
              * the portability, remap the pte with old|clean
              * after pte clearing.
              */
             ptent = ptep_get_and_clear_full(mm, addr, pte,
                             tlb->fullmm);
 
             ptent = pte_mkold(ptent);
             ptent = pte_mkclean(ptent);
             set_pte_at(mm, addr, pte, ptent);
             tlb_remove_tlb_entry(tlb, pte, addr);
         }
         mark_page_lazyfree(page);
     }
 out:
     if (nr_swap) {
         if (current->mm == mm)
             sync_mm_rss(mm);
 
         add_mm_counter(mm, MM_SWAPENTS, nr_swap);
     }
     arch_leave_lazy_mmu_mode();
     pte_unmap_unlock(orig_pte, ptl);
     cond_resched();
 next:
     return 0;
 }
 
 static const struct mm_walk_ops madvise_free_walk_ops = {
     .pmd_entry      = madvise_free_pte_range,
 };
 
 static int madvise_free_single_vma(struct vm_area_struct *vma,
             unsigned long start_addr, unsigned long end_addr)
 {
     struct mm_struct *mm = vma->vm_mm;
     struct mmu_notifier_range range;
     struct mmu_gather tlb;
 
     /* MADV_FREE works for only anon vma at the moment */
     if (!vma_is_anonymous(vma))
         return -EINVAL;
 
     range.start = max(vma->vm_start, start_addr);
     if (range.start >= vma->vm_end)
         return -EINVAL;
     range.end = min(vma->vm_end, end_addr);
     if (range.end <= vma->vm_start)
         return -EINVAL;
     mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
                 range.start, range.end);
 
     lru_add_drain();
     tlb_gather_mmu(&tlb, mm);
     update_hiwater_rss(mm);
 
     mmu_notifier_invalidate_range_start(&range);
     tlb_start_vma(&tlb, vma);
     walk_page_range(vma->vm_mm, range.start, range.end,
             &madvise_free_walk_ops, &tlb);
     tlb_end_vma(&tlb, vma);
     mmu_notifier_invalidate_range_end(&range);
     tlb_finish_mmu(&tlb);
 
     return 0;
 }
 
 /*
  * Application no longer needs these pages.  If the pages are dirty,
  * it's OK to just throw them away.  The app will be more careful about
  * data it wants to keep.  Be sure to free swap resources too.  The
  * zap_page_range call sets things up for shrink_active_list to actually free
  * these pages later if no one else has touched them in the meantime,
  * although we could add these pages to a global reuse list for
  * shrink_active_list to pick up before reclaiming other pages.
  *
  * NB: This interface discards data rather than pushes it out to swap,
  * as some implementations do.  This has performance implications for
  * applications like large transactional databases which want to discard
  * pages in anonymous maps after committing to backing store the data
  * that was kept in them.  There is no reason to write this data out to
  * the swap area if the application is discarding it.
  *
  * An interface that causes the system to free clean pages and flush
  * dirty pages is already available as msync(MS_INVALIDATE).
  */
 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
 {
     zap_page_range(vma, start, end - start);
     return 0;
 }
 
 static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
                         unsigned long start,
                         unsigned long *end,
                         int behavior)
 {
     if (!is_vm_hugetlb_page(vma)) {
         unsigned int forbidden = VM_PFNMAP;
 
         if (behavior != MADV_DONTNEED_LOCKED)
             forbidden |= VM_LOCKED;
 
         return !(vma->vm_flags & forbidden);
     }
 
     if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
         return false;
     if (start & ~huge_page_mask(hstate_vma(vma)))
         return false;
 
     *end = ALIGN(*end, huge_page_size(hstate_vma(vma)));
     return true;
 }
 
 static long madvise_dontneed_free(struct vm_area_struct *vma,
                   struct vm_area_struct **prev,
                   unsigned long start, unsigned long end,
                   int behavior)
 {
     struct mm_struct *mm = vma->vm_mm;
 
     *prev = vma;
     if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
         return -EINVAL;
 
     if (!userfaultfd_remove(vma, start, end)) {
         *prev = NULL; /* mmap_lock has been dropped, prev is stale */
 
         mmap_read_lock(mm);
         vma = find_vma(mm, start);
         if (!vma)
             return -ENOMEM;
         if (start < vma->vm_start) {
             /*
              * This "vma" under revalidation is the one
              * with the lowest vma->vm_start where start
              * is also < vma->vm_end. If start <
              * vma->vm_start it means an hole materialized
              * in the user address space within the
              * virtual range passed to MADV_DONTNEED
              * or MADV_FREE.
              */
             return -ENOMEM;
         }
         /*
          * Potential end adjustment for hugetlb vma is OK as
          * the check below keeps end within vma.
          */
         if (!madvise_dontneed_free_valid_vma(vma, start, &end,
                              behavior))
             return -EINVAL;
         if (end > vma->vm_end) {
             /*
              * Don't fail if end > vma->vm_end. If the old
              * vma was split while the mmap_lock was
              * released the effect of the concurrent
              * operation may not cause madvise() to
              * have an undefined result. There may be an
              * adjacent next vma that we'll walk
              * next. userfaultfd_remove() will generate an
              * UFFD_EVENT_REMOVE repetition on the
              * end-vma->vm_end range, but the manager can
              * handle a repetition fine.
              */
             end = vma->vm_end;
         }
         VM_WARN_ON(start >= end);
     }
 
     if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
         return madvise_dontneed_single_vma(vma, start, end);
     else if (behavior == MADV_FREE)
         return madvise_free_single_vma(vma, start, end);
     else
         return -EINVAL;
 }
 
 static long madvise_populate(struct vm_area_struct *vma,
                  struct vm_area_struct **prev,
                  unsigned long start, unsigned long end,
                  int behavior)
 {
     const bool write = behavior == MADV_POPULATE_WRITE;
     struct mm_struct *mm = vma->vm_mm;
     unsigned long tmp_end;
     int locked = 1;
     long pages;
 
     *prev = vma;
 
     while (start < end) {
         /*
          * We might have temporarily dropped the lock. For example,
          * our VMA might have been split.
          */
         if (!vma || start >= vma->vm_end) {
             vma = vma_lookup(mm, start);
             if (!vma)
                 return -ENOMEM;
         }
 
         tmp_end = min_t(unsigned long, end, vma->vm_end);
         /* Populate (prefault) page tables readable/writable. */
         pages = faultin_vma_page_range(vma, start, tmp_end, write,
                            &locked);
         if (!locked) {
             mmap_read_lock(mm);
             locked = 1;
             *prev = NULL;
             vma = NULL;
         }
         if (pages < 0) {
             switch (pages) {
             case -EINTR:
                 return -EINTR;
             case -EINVAL: /* Incompatible mappings / permissions. */
                 return -EINVAL;
             case -EHWPOISON:
                 return -EHWPOISON;
             case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
                 return -EFAULT;
             default:
                 pr_warn_once("%s: unhandled return value: %ld\n",
                          __func__, pages);
                 fallthrough;
             case -ENOMEM:
                 return -ENOMEM;
             }
         }
         start += pages * PAGE_SIZE;
     }
     return 0;
 }
 
 /*
  * Application wants to free up the pages and associated backing store.
  * This is effectively punching a hole into the middle of a file.
  */
 static long madvise_remove(struct vm_area_struct *vma,
                 struct vm_area_struct **prev,
                 unsigned long start, unsigned long end)
 {
     loff_t offset;
     int error;
     struct file *f;
     struct mm_struct *mm = vma->vm_mm;
 
     *prev = NULL;   /* tell sys_madvise we drop mmap_lock */
 
     if (vma->vm_flags & VM_LOCKED)
         return -EINVAL;
 
     f = vma->vm_file;
 
     if (!f || !f->f_mapping || !f->f_mapping->host) {
             return -EINVAL;
     }
 
     if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
         return -EACCES;
 
     offset = (loff_t)(start - vma->vm_start)
             + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 
     /*
      * Filesystem's fallocate may need to take i_rwsem.  We need to
      * explicitly grab a reference because the vma (and hence the
      * vma's reference to the file) can go away as soon as we drop
      * mmap_lock.
      */
     get_file(f);
     if (userfaultfd_remove(vma, start, end)) {
         /* mmap_lock was not released by userfaultfd_remove() */
         mmap_read_unlock(mm);
     }
     error = vfs_fallocate(f,
                 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                 offset, end - start);
     fput(f);
     mmap_read_lock(mm);
     return error;
 }
 
 /*
  * Apply an madvise behavior to a region of a vma.  madvise_update_vma
  * will handle splitting a vm area into separate areas, each area with its own
  * behavior.
  */
 static int madvise_vma_behavior(struct vm_area_struct *vma,
                 struct vm_area_struct **prev,
                 unsigned long start, unsigned long end,
                 unsigned long behavior)
 {
     int error;
     struct anon_vma_name *anon_name;
     unsigned long new_flags = vma->vm_flags;
 
     switch (behavior) {
     case MADV_REMOVE:
         return madvise_remove(vma, prev, start, end);
     case MADV_WILLNEED:
         return madvise_willneed(vma, prev, start, end);
     case MADV_COLD:
         return madvise_cold(vma, prev, start, end);
     case MADV_PAGEOUT:
         return madvise_pageout(vma, prev, start, end);
     case MADV_FREE:
     case MADV_DONTNEED:
     case MADV_DONTNEED_LOCKED:
         return madvise_dontneed_free(vma, prev, start, end, behavior);
     case MADV_POPULATE_READ:
     case MADV_POPULATE_WRITE:
         return madvise_populate(vma, prev, start, end, behavior);
     case MADV_NORMAL:
         new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
         break;
     case MADV_SEQUENTIAL:
         new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
         break;
     case MADV_RANDOM:
         new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
         break;
     case MADV_DONTFORK:
         new_flags |= VM_DONTCOPY;
         break;
     case MADV_DOFORK:
         if (vma->vm_flags & VM_IO)
             return -EINVAL;
         new_flags &= ~VM_DONTCOPY;
         break;
     case MADV_WIPEONFORK:
         /* MADV_WIPEONFORK is only supported on anonymous memory. */
         if (vma->vm_file || vma->vm_flags & VM_SHARED)
             return -EINVAL;
         new_flags |= VM_WIPEONFORK;
         break;
     case MADV_KEEPONFORK:
         new_flags &= ~VM_WIPEONFORK;
         break;
     case MADV_DONTDUMP:
         new_flags |= VM_DONTDUMP;
         break;
     case MADV_DODUMP:
         if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
             return -EINVAL;
         new_flags &= ~VM_DONTDUMP;
         break;
     case MADV_MERGEABLE:
     case MADV_UNMERGEABLE:
         error = ksm_madvise(vma, start, end, behavior, &new_flags);
         if (error)
             goto out;
         break;
     case MADV_HUGEPAGE:
     case MADV_NOHUGEPAGE:
         error = hugepage_madvise(vma, &new_flags, behavior);
         if (error)
             goto out;
         break;
     }
 
     anon_name = anon_vma_name(vma);
     anon_vma_name_get(anon_name);
     error = madvise_update_vma(vma, prev, start, end, new_flags,
                    anon_name);
     anon_vma_name_put(anon_name);
 
 out:
     /*
      * madvise() returns EAGAIN if kernel resources, such as
      * slab, are temporarily unavailable.
      */
     if (error == -ENOMEM)
         error = -EAGAIN;
     return error;
 }
 
 #ifdef CONFIG_MEMORY_FAILURE
 /*
  * Error injection support for memory error handling.
  */
 static int madvise_inject_error(int behavior,
         unsigned long start, unsigned long end)
 {
     unsigned long size;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
 
     for (; start < end; start += size) {
         unsigned long pfn;
         struct page *page;
         int ret;
 
         ret = get_user_pages_fast(start, 1, 0, &page);
         if (ret != 1)
             return ret;
         pfn = page_to_pfn(page);
 
         /*
          * When soft offlining hugepages, after migrating the page
          * we dissolve it, therefore in the second loop "page" will
          * no longer be a compound page.
          */
         size = page_size(compound_head(page));
 
         if (behavior == MADV_SOFT_OFFLINE) {
             pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
                  pfn, start);
             ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
         } else {
             pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
                  pfn, start);
             ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
             if (ret == -EOPNOTSUPP)
                 ret = 0;
         }
 
         if (ret)
             return ret;
     }
 
     return 0;
 }
 #endif
 
 static bool
 madvise_behavior_valid(int behavior)
 {
     switch (behavior) {
     case MADV_DOFORK:
     case MADV_DONTFORK:
     case MADV_NORMAL:
     case MADV_SEQUENTIAL:
     case MADV_RANDOM:
     case MADV_REMOVE:
     case MADV_WILLNEED:
     case MADV_DONTNEED:
     case MADV_DONTNEED_LOCKED:
     case MADV_FREE:
     case MADV_COLD:
     case MADV_PAGEOUT:
     case MADV_POPULATE_READ:
     case MADV_POPULATE_WRITE:
 #ifdef CONFIG_KSM
     case MADV_MERGEABLE:
     case MADV_UNMERGEABLE:
 #endif
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
     case MADV_HUGEPAGE:
     case MADV_NOHUGEPAGE:
 #endif
     case MADV_DONTDUMP:
     case MADV_DODUMP:
     case MADV_WIPEONFORK:
     case MADV_KEEPONFORK:
 #ifdef CONFIG_MEMORY_FAILURE
     case MADV_SOFT_OFFLINE:
     case MADV_HWPOISON:
 #endif
         return true;
 
     default:
         return false;
     }
 }
 
 static bool
 process_madvise_behavior_valid(int behavior)
 {
     switch (behavior) {
     case MADV_COLD:
     case MADV_PAGEOUT:
     case MADV_WILLNEED:
         return true;
     default:
         return false;
     }
 }
 
 /*
  * Walk the vmas in range [start,end), and call the visit function on each one.
  * The visit function will get start and end parameters that cover the overlap
  * between the current vma and the original range.  Any unmapped regions in the
  * original range will result in this function returning -ENOMEM while still
  * calling the visit function on all of the existing vmas in the range.
  * Must be called with the mmap_lock held for reading or writing.
  */
 static
 int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
               unsigned long end, unsigned long arg,
               int (*visit)(struct vm_area_struct *vma,
                    struct vm_area_struct **prev, unsigned long start,
                    unsigned long end, unsigned long arg))
 {
     struct vm_area_struct *vma;
     struct vm_area_struct *prev;
     unsigned long tmp;
     int unmapped_error = 0;
 
     /*
      * If the interval [start,end) covers some unmapped address
      * ranges, just ignore them, but return -ENOMEM at the end.
      * - different from the way of handling in mlock etc.
      */
     vma = find_vma_prev(mm, start, &prev);
     if (vma && start > vma->vm_start)
         prev = vma;
 
     for (;;) {
         int error;
 
         /* Still start < end. */
         if (!vma)
             return -ENOMEM;
 
         /* Here start < (end|vma->vm_end). */
         if (start < vma->vm_start) {
             unmapped_error = -ENOMEM;
             start = vma->vm_start;
             if (start >= end)
                 break;
         }
 
         /* Here vma->vm_start <= start < (end|vma->vm_end) */
         tmp = vma->vm_end;
         if (end < tmp)
             tmp = end;
 
         /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
         error = visit(vma, &prev, start, tmp, arg);
         if (error)
             return error;
         start = tmp;
         if (prev && start < prev->vm_end)
             start = prev->vm_end;
         if (start >= end)
             break;
         if (prev)
             vma = prev->vm_next;
         else    /* madvise_remove dropped mmap_lock */
             vma = find_vma(mm, start);
     }
 
     return unmapped_error;
 }
 
 #ifdef CONFIG_ANON_VMA_NAME
 static int madvise_vma_anon_name(struct vm_area_struct *vma,
                  struct vm_area_struct **prev,
                  unsigned long start, unsigned long end,
                  unsigned long anon_name)
 {
     int error;
 
     /* Only anonymous mappings can be named */
     if (vma->vm_file)
         return -EBADF;
 
     error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
                    (struct anon_vma_name *)anon_name);
 
     /*
      * madvise() returns EAGAIN if kernel resources, such as
      * slab, are temporarily unavailable.
      */
     if (error == -ENOMEM)
         error = -EAGAIN;
     return error;
 }
 
 int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
               unsigned long len_in, struct anon_vma_name *anon_name)
 {
     unsigned long end;
     unsigned long len;
 
     if (start & ~PAGE_MASK)
         return -EINVAL;
     len = (len_in + ~PAGE_MASK) & PAGE_MASK;
 
     /* Check to see whether len was rounded up from small -ve to zero */
     if (len_in && !len)
         return -EINVAL;
 
     end = start + len;
     if (end < start)
         return -EINVAL;
 
     if (end == start)
         return 0;
 
     return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
                  madvise_vma_anon_name);
 }
 #endif /* CONFIG_ANON_VMA_NAME */
 /*
  * The madvise(2) system call.
  *
  * Applications can use madvise() to advise the kernel how it should
  * handle paging I/O in this VM area.  The idea is to help the kernel
  * use appropriate read-ahead and caching techniques.  The information
  * provided is advisory only, and can be safely disregarded by the
  * kernel without affecting the correct operation of the application.
  *
  * behavior values:
  *  MADV_NORMAL - the default behavior is to read clusters.  This
  *      results in some read-ahead and read-behind.
  *  MADV_RANDOM - the system should read the minimum amount of data
  *      on any access, since it is unlikely that the appli-
  *      cation will need more than what it asks for.
  *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
  *      once, so they can be aggressively read ahead, and
  *      can be freed soon after they are accessed.
  *  MADV_WILLNEED - the application is notifying the system to read
  *      some pages ahead.
  *  MADV_DONTNEED - the application is finished with the given range,
  *      so the kernel can free resources associated with it.
  *  MADV_FREE - the application marks pages in the given range as lazy free,
  *      where actual purges are postponed until memory pressure happens.
  *  MADV_REMOVE - the application wants to free up the given range of
  *      pages and associated backing store.
  *  MADV_DONTFORK - omit this area from child's address space when forking:
  *      typically, to avoid COWing pages pinned by get_user_pages().
  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
  *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
  *              range after a fork.
  *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
  *  MADV_HWPOISON - trigger memory error handler as if the given memory range
  *      were corrupted by unrecoverable hardware memory failure.
  *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
  *      this area with pages of identical content from other such areas.
  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
  *  MADV_HUGEPAGE - the application wants to back the given range by transparent
  *      huge pages in the future. Existing pages might be coalesced and
  *      new pages might be allocated as THP.
  *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
  *      transparent huge pages so the existing pages will not be
  *      coalesced into THP and new pages will not be allocated as THP.
  *  MADV_DONTDUMP - the application wants to prevent pages in the given range
  *      from being included in its core dump.
  *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
  *  MADV_COLD - the application is not expected to use this memory soon,
  *      deactivate pages in this range so that they can be reclaimed
  *      easily if memory pressure happens.
  *  MADV_PAGEOUT - the application is not expected to use this memory soon,
  *      page out the pages in this range immediately.
  *  MADV_POPULATE_READ - populate (prefault) page tables readable by
  *      triggering read faults if required
  *  MADV_POPULATE_WRITE - populate (prefault) page tables writable by
  *      triggering write faults if required
  *
  * return values:
  *  zero    - success
  *  -EINVAL - start + len < 0, start is not page-aligned,
  *      "behavior" is not a valid value, or application
  *      is attempting to release locked or shared pages,
  *      or the specified address range includes file, Huge TLB,
  *      MAP_SHARED or VMPFNMAP range.
  *  -ENOMEM - addresses in the specified range are not currently
  *      mapped, or are outside the AS of the process.
  *  -EIO    - an I/O error occurred while paging in data.
  *  -EBADF  - map exists, but area maps something that isn't a file.
  *  -EAGAIN - a kernel resource was temporarily unavailable.
  */
 int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
 {
     unsigned long end;
     int error;
     int write;
     size_t len;
     struct blk_plug plug;
 
     start = untagged_addr(start);
 
     if (!madvise_behavior_valid(behavior))
         return -EINVAL;
 
     if (!PAGE_ALIGNED(start))
         return -EINVAL;
     len = PAGE_ALIGN(len_in);
 
     /* Check to see whether len was rounded up from small -ve to zero */
     if (len_in && !len)
         return -EINVAL;
 
     end = start + len;
     if (end < start)
         return -EINVAL;
 
     if (end == start)
         return 0;
 
 #ifdef CONFIG_MEMORY_FAILURE
     if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
         return madvise_inject_error(behavior, start, start + len_in);
 #endif
 
     write = madvise_need_mmap_write(behavior);
     if (write) {
         if (mmap_write_lock_killable(mm))
             return -EINTR;
     } else {
         mmap_read_lock(mm);
     }
 
     blk_start_plug(&plug);
     error = madvise_walk_vmas(mm, start, end, behavior,
             madvise_vma_behavior);
     blk_finish_plug(&plug);
     if (write)
         mmap_write_unlock(mm);
     else
         mmap_read_unlock(mm);
 
     return error;
 }
 
 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
 {
     return do_madvise(current->mm, start, len_in, behavior);
 }
 
 SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
         size_t, vlen, int, behavior, unsigned int, flags)
 {
     ssize_t ret;
     struct iovec iovstack[UIO_FASTIOV], iovec;
     struct iovec *iov = iovstack;
     struct iov_iter iter;
     struct task_struct *task;
     struct mm_struct *mm;
     size_t total_len;
     unsigned int f_flags;
 
     if (flags != 0) {
         ret = -EINVAL;
         goto out;
     }
 
     ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
     if (ret < 0)
         goto out;
 
     task = pidfd_get_task(pidfd, &f_flags);
     if (IS_ERR(task)) {
         ret = PTR_ERR(task);
         goto free_iov;
     }
 
     if (!process_madvise_behavior_valid(behavior)) {
         ret = -EINVAL;
         goto release_task;
     }
 
     /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
     mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
     if (IS_ERR_OR_NULL(mm)) {
         ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
         goto release_task;
     }
 
     /*
      * Require CAP_SYS_NICE for influencing process performance. Note that
      * only non-destructive hints are currently supported.
      */
     if (!capable(CAP_SYS_NICE)) {
         ret = -EPERM;
         goto release_mm;
     }
 
     total_len = iov_iter_count(&iter);
 
     while (iov_iter_count(&iter)) {
         iovec = iov_iter_iovec(&iter);
         ret = do_madvise(mm, (unsigned long)iovec.iov_base,
                     iovec.iov_len, behavior);
         if (ret < 0)
             break;
         iov_iter_advance(&iter, iovec.iov_len);
     }
 
     ret = (total_len - iov_iter_count(&iter)) ? : ret;
 
 release_mm:
     mmput(mm);
 release_task:
     put_task_struct(task);
 free_iov:
     kfree(iov);
 out:
     return ret;
 }

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