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-rw-r--r--mm/madvise.c1514
1 files changed, 1514 insertions, 0 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
new file mode 100644
index 000000000..5973399b2
--- /dev/null
+++ b/mm/madvise.c
@@ -0,0 +1,1514 @@
+// 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:
+ case MADV_COLLAPSE:
+ 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 folio *folio;
+ 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;
+ folio = page_folio(page);
+
+ /*
+ * If pmd isn't transhuge but the folio is large and
+ * is owned by only this process, split it and
+ * deactivate all pages.
+ */
+ if (folio_test_large(folio)) {
+ if (folio_estimated_sharers(folio) != 1)
+ break;
+ folio_get(folio);
+ if (!folio_trylock(folio)) {
+ folio_put(folio);
+ goto out;
+ }
+ pte_unmap_unlock(orig_pte, ptl);
+ if (split_folio(folio)) {
+ folio_unlock(folio);
+ folio_put(folio);
+ orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ goto out;
+ }
+ folio_unlock(folio);
+ folio_put(folio);
+ orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ pte--;
+ addr -= PAGE_SIZE;
+ continue;
+ }
+
+ if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
+ if (!folio_trylock(folio))
+ continue;
+ /*
+ * If folio is shared with others, we mustn't clear
+ * the folio's dirty flag.
+ */
+ if (folio_mapcount(folio) != 1) {
+ folio_unlock(folio);
+ continue;
+ }
+
+ if (folio_test_swapcache(folio) &&
+ !folio_free_swap(folio)) {
+ folio_unlock(folio);
+ continue;
+ }
+
+ folio_clear_dirty(folio);
+ folio_unlock(folio);
+ }
+
+ 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(&folio->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_single 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_single(vma, start, end - start, NULL);
+ 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;
+
+ /*
+ * Madvise callers expect the length to be rounded up to PAGE_SIZE
+ * boundaries, and may be unaware that this VMA uses huge pages.
+ * Avoid unexpected data loss by rounding down the number of
+ * huge pages freed.
+ */
+ *end = ALIGN_DOWN(*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 (start == end)
+ return 0;
+
+ 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;
+ case MADV_COLLAPSE:
+ return madvise_collapse(vma, prev, start, end);
+ }
+
+ 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:
+ case MADV_COLLAPSE:
+#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:
+ case MADV_COLLAPSE:
+ 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 = find_vma(mm, prev->vm_end);
+ 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_COLLAPSE - synchronously coalesce pages into new 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(ITER_DEST, 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;
+}