Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1534 insertions, 0 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
new file mode 100644
index 0000000000..4dded5d27e
--- /dev/null
+++ b/mm/madvise.c
@@ -0,0 +1,1534 @@
+// 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);
+
+	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_lock 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;
+	VMA_ITERATOR(vmi, mm, start);
+
+	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(&vmi, 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) {
+		error = split_vma(&vmi, vma, start, 1);
+		if (error)
+			return error;
+	}
+
+	if (end != vma->vm_end) {
+		error = split_vma(&vmi, vma, end, 0);
+		if (error)
+			return error;
+	}
+
+success:
+	/* vm_flags is protected by the mmap_lock held in write mode. */
+	vma_start_write(vma);
+	vm_flags_reset(vma, new_flags);
+	if (!vma->vm_file || vma_is_anon_shmem(vma)) {
+		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;
+	struct swap_iocb *splug = NULL;
+	pte_t *ptep = NULL;
+	spinlock_t *ptl;
+	unsigned long addr;
+
+	for (addr = start; addr < end; addr += PAGE_SIZE) {
+		pte_t pte;
+		swp_entry_t entry;
+		struct page *page;
+
+		if (!ptep++) {
+			ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+			if (!ptep)
+				break;
+		}
+
+		pte = ptep_get(ptep);
+		if (!is_swap_pte(pte))
+			continue;
+		entry = pte_to_swp_entry(pte);
+		if (unlikely(non_swap_entry(entry)))
+			continue;
+
+		pte_unmap_unlock(ptep, ptl);
+		ptep = NULL;
+
+		page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
+					     vma, addr, &splug);
+		if (page)
+			put_page(page);
+	}
+
+	if (ptep)
+		pte_unmap_unlock(ptep, ptl);
+	swap_read_unplug(splug);
+	cond_resched();
+
+	return 0;
+}
+
+static const struct mm_walk_ops swapin_walk_ops = {
+	.pmd_entry		= swapin_walk_pmd_entry,
+	.walk_lock		= PGWALK_RDLOCK,
+};
+
+static void shmem_swapin_range(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) - 1;
+	struct page *page;
+	struct swap_iocb *splug = NULL;
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, end_index) {
+		unsigned long addr;
+		swp_entry_t entry;
+
+		if (!xa_is_value(page))
+			continue;
+		entry = radix_to_swp_entry(page);
+		/* There might be swapin error entries in shmem mapping. */
+		if (non_swap_entry(entry))
+			continue;
+
+		addr = vma->vm_start +
+			((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
+		xas_pause(&xas);
+		rcu_read_unlock();
+
+		page = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
+					     vma, addr, &splug);
+		if (page)
+			put_page(page);
+
+		rcu_read_lock();
+	}
+	rcu_read_unlock();
+	swap_read_unplug(splug);
+}
+#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)) {
+		shmem_swapin_range(vma, start, end, file->f_mapping);
+		lru_add_drain(); /* Push any new pages onto the LRU now */
+		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 inline bool can_do_file_pageout(struct vm_area_struct *vma)
+{
+	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(&nop_mnt_idmap,
+				      file_inode(vma->vm_file)) ||
+	       file_permission(vma->vm_file, MAY_WRITE) == 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 *start_pte, *pte, ptent;
+	spinlock_t *ptl;
+	struct folio *folio = NULL;
+	LIST_HEAD(folio_list);
+	bool pageout_anon_only_filter;
+
+	if (fatal_signal_pending(current))
+		return -EINTR;
+
+	pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
+					!can_do_file_pageout(vma);
+
+#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;
+		}
+
+		folio = pfn_folio(pmd_pfn(orig_pmd));
+
+		/* Do not interfere with other mappings of this folio */
+		if (folio_estimated_sharers(folio) != 1)
+			goto huge_unlock;
+
+		if (pageout_anon_only_filter && !folio_test_anon(folio))
+			goto huge_unlock;
+
+		if (next - addr != HPAGE_PMD_SIZE) {
+			int err;
+
+			folio_get(folio);
+			spin_unlock(ptl);
+			folio_lock(folio);
+			err = split_folio(folio);
+			folio_unlock(folio);
+			folio_put(folio);
+			if (!err)
+				goto regular_folio;
+			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);
+		}
+
+		folio_clear_referenced(folio);
+		folio_test_clear_young(folio);
+		if (folio_test_active(folio))
+			folio_set_workingset(folio);
+		if (pageout) {
+			if (folio_isolate_lru(folio)) {
+				if (folio_test_unevictable(folio))
+					folio_putback_lru(folio);
+				else
+					list_add(&folio->lru, &folio_list);
+			}
+		} else
+			folio_deactivate(folio);
+huge_unlock:
+		spin_unlock(ptl);
+		if (pageout)
+			reclaim_pages(&folio_list);
+		return 0;
+	}
+
+regular_folio:
+#endif
+	tlb_change_page_size(tlb, PAGE_SIZE);
+	start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (!start_pte)
+		return 0;
+	flush_tlb_batched_pending(mm);
+	arch_enter_lazy_mmu_mode();
+	for (; addr < end; pte++, addr += PAGE_SIZE) {
+		ptent = ptep_get(pte);
+
+		if (pte_none(ptent))
+			continue;
+
+		if (!pte_present(ptent))
+			continue;
+
+		folio = vm_normal_folio(vma, addr, ptent);
+		if (!folio || folio_is_zone_device(folio))
+			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 (folio_test_large(folio)) {
+			int err;
+
+			if (folio_estimated_sharers(folio) != 1)
+				break;
+			if (pageout_anon_only_filter && !folio_test_anon(folio))
+				break;
+			if (!folio_trylock(folio))
+				break;
+			folio_get(folio);
+			arch_leave_lazy_mmu_mode();
+			pte_unmap_unlock(start_pte, ptl);
+			start_pte = NULL;
+			err = split_folio(folio);
+			folio_unlock(folio);
+			folio_put(folio);
+			if (err)
+				break;
+			start_pte = pte =
+				pte_offset_map_lock(mm, pmd, addr, &ptl);
+			if (!start_pte)
+				break;
+			arch_enter_lazy_mmu_mode();
+			pte--;
+			addr -= PAGE_SIZE;
+			continue;
+		}
+
+		/*
+		 * Do not interfere with other mappings of this folio and
+		 * non-LRU folio.
+		 */
+		if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
+			continue;
+
+		if (pageout_anon_only_filter && !folio_test_anon(folio))
+			continue;
+
+		VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
+
+		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 folio for accelerating reclaiming.
+		 * VM couldn't reclaim the folio unless we clear PG_young.
+		 * As a side effect, it makes confuse idle-page tracking
+		 * because they will miss recent referenced history.
+		 */
+		folio_clear_referenced(folio);
+		folio_test_clear_young(folio);
+		if (folio_test_active(folio))
+			folio_set_workingset(folio);
+		if (pageout) {
+			if (folio_isolate_lru(folio)) {
+				if (folio_test_unevictable(folio))
+					folio_putback_lru(folio);
+				else
+					list_add(&folio->lru, &folio_list);
+			}
+		} else
+			folio_deactivate(folio);
+	}
+
+	if (start_pte) {
+		arch_leave_lazy_mmu_mode();
+		pte_unmap_unlock(start_pte, ptl);
+	}
+	if (pageout)
+		reclaim_pages(&folio_list);
+	cond_resched();
+
+	return 0;
+}
+
+static const struct mm_walk_ops cold_walk_ops = {
+	.pmd_entry = madvise_cold_or_pageout_pte_range,
+	.walk_lock = PGWALK_RDLOCK,
+};
+
+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 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 the VMA belongs to a private file mapping, there can be private
+	 * dirty pages which can be paged out if even this process is neither
+	 * owner nor write capable of the file. We allow private file mappings
+	 * further to pageout dirty anon pages.
+	 */
+	if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
+				(vma->vm_flags & VM_MAYSHARE)))
+		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 *start_pte, *pte, ptent;
+	struct folio *folio;
+	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))
+			return 0;
+
+	tlb_change_page_size(tlb, PAGE_SIZE);
+	start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	if (!start_pte)
+		return 0;
+	flush_tlb_batched_pending(mm);
+	arch_enter_lazy_mmu_mode();
+	for (; addr != end; pte++, addr += PAGE_SIZE) {
+		ptent = ptep_get(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_poisoned_swp_entry(entry)) {
+				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+			}
+			continue;
+		}
+
+		folio = vm_normal_folio(vma, addr, ptent);
+		if (!folio || folio_is_zone_device(folio))
+			continue;
+
+		/*
+		 * 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)) {
+			int err;
+
+			if (folio_estimated_sharers(folio) != 1)
+				break;
+			if (!folio_trylock(folio))
+				break;
+			folio_get(folio);
+			arch_leave_lazy_mmu_mode();
+			pte_unmap_unlock(start_pte, ptl);
+			start_pte = NULL;
+			err = split_folio(folio);
+			folio_unlock(folio);
+			folio_put(folio);
+			if (err)
+				break;
+			start_pte = pte =
+				pte_offset_map_lock(mm, pmd, addr, &ptl);
+			if (!start_pte)
+				break;
+			arch_enter_lazy_mmu_mode();
+			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);
+		}
+		folio_mark_lazyfree(folio);
+	}
+
+	if (nr_swap) {
+		if (current->mm == mm)
+			sync_mm_rss(mm);
+		add_mm_counter(mm, MM_SWAPENTS, nr_swap);
+	}
+	if (start_pte) {
+		arch_leave_lazy_mmu_mode();
+		pte_unmap_unlock(start_pte, ptl);
+	}
+	cond_resched();
+
+	return 0;
+}
+
+static const struct mm_walk_ops madvise_free_walk_ops = {
+	.pmd_entry		= madvise_free_pte_range,
+	.walk_lock		= PGWALK_RDLOCK,
+};
+
+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, 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 = vma_lookup(mm, start);
+		if (!vma)
+			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 && !vma_is_anon_shmem(vma))
+		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;
+
+	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);
+	}
+
+	start = untagged_addr_remote(mm, start);
+	end = start + len;
+
+	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];
+	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)) {
+		ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
+					iter_iov_len(&iter), behavior);
+		if (ret < 0)
+			break;
+		iov_iter_advance(&iter, iter_iov_len(&iter));
+	}
+
+	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;
+}