mm: move the migrate_vma_* device migration code into its own file

Split the code used to migrate to and from ZONE_DEVICE memory from
migrate.c into a new file.

Link: https://lkml.kernel.org/r/20220210072828.2930359-14-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

1 files changed, 0 insertions, 753 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 7dffd5f82a60d..f4076093c8554 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -38,12 +38,10 @@
 #include <linux/hugetlb.h>
 #include <linux/hugetlb_cgroup.h>
 #include <linux/gfp.h>
-#include <linux/pagewalk.h>
 #include <linux/pfn_t.h>
 #include <linux/memremap.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/balloon_compaction.h>
-#include <linux/mmu_notifier.h>
 #include <linux/page_idle.h>
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
@@ -2129,757 +2127,6 @@ out:
 #endif /* CONFIG_NUMA_BALANCING */
 #endif /* CONFIG_NUMA */
 
-#ifdef CONFIG_DEVICE_PRIVATE
-static int migrate_vma_collect_skip(unsigned long start,
-				    unsigned long end,
-				    struct mm_walk *walk)
-{
-	struct migrate_vma *migrate = walk->private;
-	unsigned long addr;
-
-	for (addr = start; addr < end; addr += PAGE_SIZE) {
-		migrate->dst[migrate->npages] = 0;
-		migrate->src[migrate->npages++] = 0;
-	}
-
-	return 0;
-}
-
-static int migrate_vma_collect_hole(unsigned long start,
-				    unsigned long end,
-				    __always_unused int depth,
-				    struct mm_walk *walk)
-{
-	struct migrate_vma *migrate = walk->private;
-	unsigned long addr;
-
-	/* Only allow populating anonymous memory. */
-	if (!vma_is_anonymous(walk->vma))
-		return migrate_vma_collect_skip(start, end, walk);
-
-	for (addr = start; addr < end; addr += PAGE_SIZE) {
-		migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
-		migrate->dst[migrate->npages] = 0;
-		migrate->npages++;
-		migrate->cpages++;
-	}
-
-	return 0;
-}
-
-static int migrate_vma_collect_pmd(pmd_t *pmdp,
-				   unsigned long start,
-				   unsigned long end,
-				   struct mm_walk *walk)
-{
-	struct migrate_vma *migrate = walk->private;
-	struct vm_area_struct *vma = walk->vma;
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long addr = start, unmapped = 0;
-	spinlock_t *ptl;
-	pte_t *ptep;
-
-again:
-	if (pmd_none(*pmdp))
-		return migrate_vma_collect_hole(start, end, -1, walk);
-
-	if (pmd_trans_huge(*pmdp)) {
-		struct page *page;
-
-		ptl = pmd_lock(mm, pmdp);
-		if (unlikely(!pmd_trans_huge(*pmdp))) {
-			spin_unlock(ptl);
-			goto again;
-		}
-
-		page = pmd_page(*pmdp);
-		if (is_huge_zero_page(page)) {
-			spin_unlock(ptl);
-			split_huge_pmd(vma, pmdp, addr);
-			if (pmd_trans_unstable(pmdp))
-				return migrate_vma_collect_skip(start, end,
-								walk);
-		} else {
-			int ret;
-
-			get_page(page);
-			spin_unlock(ptl);
-			if (unlikely(!trylock_page(page)))
-				return migrate_vma_collect_skip(start, end,
-								walk);
-			ret = split_huge_page(page);
-			unlock_page(page);
-			put_page(page);
-			if (ret)
-				return migrate_vma_collect_skip(start, end,
-								walk);
-			if (pmd_none(*pmdp))
-				return migrate_vma_collect_hole(start, end, -1,
-								walk);
-		}
-	}
-
-	if (unlikely(pmd_bad(*pmdp)))
-		return migrate_vma_collect_skip(start, end, walk);
-
-	ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
-	arch_enter_lazy_mmu_mode();
-
-	for (; addr < end; addr += PAGE_SIZE, ptep++) {
-		unsigned long mpfn = 0, pfn;
-		struct page *page;
-		swp_entry_t entry;
-		pte_t pte;
-
-		pte = *ptep;
-
-		if (pte_none(pte)) {
-			if (vma_is_anonymous(vma)) {
-				mpfn = MIGRATE_PFN_MIGRATE;
-				migrate->cpages++;
-			}
-			goto next;
-		}
-
-		if (!pte_present(pte)) {
-			/*
-			 * Only care about unaddressable device page special
-			 * page table entry. Other special swap entries are not
-			 * migratable, and we ignore regular swapped page.
-			 */
-			entry = pte_to_swp_entry(pte);
-			if (!is_device_private_entry(entry))
-				goto next;
-
-			page = pfn_swap_entry_to_page(entry);
-			if (!(migrate->flags &
-				MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
-			    page->pgmap->owner != migrate->pgmap_owner)
-				goto next;
-
-			mpfn = migrate_pfn(page_to_pfn(page)) |
-					MIGRATE_PFN_MIGRATE;
-			if (is_writable_device_private_entry(entry))
-				mpfn |= MIGRATE_PFN_WRITE;
-		} else {
-			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
-				goto next;
-			pfn = pte_pfn(pte);
-			if (is_zero_pfn(pfn)) {
-				mpfn = MIGRATE_PFN_MIGRATE;
-				migrate->cpages++;
-				goto next;
-			}
-			page = vm_normal_page(migrate->vma, addr, pte);
-			mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
-			mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
-		}
-
-		/* FIXME support THP */
-		if (!page || !page->mapping || PageTransCompound(page)) {
-			mpfn = 0;
-			goto next;
-		}
-
-		/*
-		 * By getting a reference on the page we pin it and that blocks
-		 * any kind of migration. Side effect is that it "freezes" the
-		 * pte.
-		 *
-		 * We drop this reference after isolating the page from the lru
-		 * for non device page (device page are not on the lru and thus
-		 * can't be dropped from it).
-		 */
-		get_page(page);
-
-		/*
-		 * Optimize for the common case where page is only mapped once
-		 * in one process. If we can lock the page, then we can safely
-		 * set up a special migration page table entry now.
-		 */
-		if (trylock_page(page)) {
-			pte_t swp_pte;
-
-			migrate->cpages++;
-			ptep_get_and_clear(mm, addr, ptep);
-
-			/* Setup special migration page table entry */
-			if (mpfn & MIGRATE_PFN_WRITE)
-				entry = make_writable_migration_entry(
-							page_to_pfn(page));
-			else
-				entry = make_readable_migration_entry(
-							page_to_pfn(page));
-			swp_pte = swp_entry_to_pte(entry);
-			if (pte_present(pte)) {
-				if (pte_soft_dirty(pte))
-					swp_pte = pte_swp_mksoft_dirty(swp_pte);
-				if (pte_uffd_wp(pte))
-					swp_pte = pte_swp_mkuffd_wp(swp_pte);
-			} else {
-				if (pte_swp_soft_dirty(pte))
-					swp_pte = pte_swp_mksoft_dirty(swp_pte);
-				if (pte_swp_uffd_wp(pte))
-					swp_pte = pte_swp_mkuffd_wp(swp_pte);
-			}
-			set_pte_at(mm, addr, ptep, swp_pte);
-
-			/*
-			 * This is like regular unmap: we remove the rmap and
-			 * drop page refcount. Page won't be freed, as we took
-			 * a reference just above.
-			 */
-			page_remove_rmap(page, vma, false);
-			put_page(page);
-
-			if (pte_present(pte))
-				unmapped++;
-		} else {
-			put_page(page);
-			mpfn = 0;
-		}
-
-next:
-		migrate->dst[migrate->npages] = 0;
-		migrate->src[migrate->npages++] = mpfn;
-	}
-	arch_leave_lazy_mmu_mode();
-	pte_unmap_unlock(ptep - 1, ptl);
-
-	/* Only flush the TLB if we actually modified any entries */
-	if (unmapped)
-		flush_tlb_range(walk->vma, start, end);
-
-	return 0;
-}
-
-static const struct mm_walk_ops migrate_vma_walk_ops = {
-	.pmd_entry		= migrate_vma_collect_pmd,
-	.pte_hole		= migrate_vma_collect_hole,
-};
-
-/*
- * migrate_vma_collect() - collect pages over a range of virtual addresses
- * @migrate: migrate struct containing all migration information
- *
- * This will walk the CPU page table. For each virtual address backed by a
- * valid page, it updates the src array and takes a reference on the page, in
- * order to pin the page until we lock it and unmap it.
- */
-static void migrate_vma_collect(struct migrate_vma *migrate)
-{
-	struct mmu_notifier_range range;
-
-	/*
-	 * Note that the pgmap_owner is passed to the mmu notifier callback so
-	 * that the registered device driver can skip invalidating device
-	 * private page mappings that won't be migrated.
-	 */
-	mmu_notifier_range_init_owner(&range, MMU_NOTIFY_MIGRATE, 0,
-		migrate->vma, migrate->vma->vm_mm, migrate->start, migrate->end,
-		migrate->pgmap_owner);
-	mmu_notifier_invalidate_range_start(&range);
-
-	walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end,
-			&migrate_vma_walk_ops, migrate);
-
-	mmu_notifier_invalidate_range_end(&range);
-	migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT);
-}
-
-/*
- * migrate_vma_check_page() - check if page is pinned or not
- * @page: struct page to check
- *
- * Pinned pages cannot be migrated. This is the same test as in
- * folio_migrate_mapping(), except that here we allow migration of a
- * ZONE_DEVICE page.
- */
-static bool migrate_vma_check_page(struct page *page)
-{
-	/*
-	 * One extra ref because caller holds an extra reference, either from
-	 * isolate_lru_page() for a regular page, or migrate_vma_collect() for
-	 * a device page.
-	 */
-	int extra = 1;
-
-	/*
-	 * FIXME support THP (transparent huge page), it is bit more complex to
-	 * check them than regular pages, because they can be mapped with a pmd
-	 * or with a pte (split pte mapping).
-	 */
-	if (PageCompound(page))
-		return false;
-
-	/* Page from ZONE_DEVICE have one extra reference */
-	if (is_zone_device_page(page))
-		extra++;
-
-	/* For file back page */
-	if (page_mapping(page))
-		extra += 1 + page_has_private(page);
-
-	if ((page_count(page) - extra) > page_mapcount(page))
-		return false;
-
-	return true;
-}
-
-/*
- * migrate_vma_unmap() - replace page mapping with special migration pte entry
- * @migrate: migrate struct containing all migration information
- *
- * Isolate pages from the LRU and replace mappings (CPU page table pte) with a
- * special migration pte entry and check if it has been pinned. Pinned pages are
- * restored because we cannot migrate them.
- *
- * This is the last step before we call the device driver callback to allocate
- * destination memory and copy contents of original page over to new page.
- */
-static void migrate_vma_unmap(struct migrate_vma *migrate)
-{
-	const unsigned long npages = migrate->npages;
-	unsigned long i, restore = 0;
-	bool allow_drain = true;
-
-	lru_add_drain();
-
-	for (i = 0; i < npages; i++) {
-		struct page *page = migrate_pfn_to_page(migrate->src[i]);
-
-		if (!page)
-			continue;
-
-		/* ZONE_DEVICE pages are not on LRU */
-		if (!is_zone_device_page(page)) {
-			if (!PageLRU(page) && allow_drain) {
-				/* Drain CPU's pagevec */
-				lru_add_drain_all();
-				allow_drain = false;
-			}
-
-			if (isolate_lru_page(page)) {
-				migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-				migrate->cpages--;
-				restore++;
-				continue;
-			}
-
-			/* Drop the reference we took in collect */
-			put_page(page);
-		}
-
-		if (page_mapped(page))
-			try_to_migrate(page, 0);
-
-		if (page_mapped(page) || !migrate_vma_check_page(page)) {
-			if (!is_zone_device_page(page)) {
-				get_page(page);
-				putback_lru_page(page);
-			}
-
-			migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-			migrate->cpages--;
-			restore++;
-			continue;
-		}
-	}
-
-	for (i = 0; i < npages && restore; i++) {
-		struct page *page = migrate_pfn_to_page(migrate->src[i]);
-
-		if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE))
-			continue;
-
-		remove_migration_ptes(page, page, false);
-
-		migrate->src[i] = 0;
-		unlock_page(page);
-		put_page(page);
-		restore--;
-	}
-}
-
-/**
- * migrate_vma_setup() - prepare to migrate a range of memory
- * @args: contains the vma, start, and pfns arrays for the migration
- *
- * Returns: negative errno on failures, 0 when 0 or more pages were migrated
- * without an error.
- *
- * Prepare to migrate a range of memory virtual address range by collecting all
- * the pages backing each virtual address in the range, saving them inside the
- * src array.  Then lock those pages and unmap them. Once the pages are locked
- * and unmapped, check whether each page is pinned or not.  Pages that aren't
- * pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) in the
- * corresponding src array entry.  Then restores any pages that are pinned, by
- * remapping and unlocking those pages.
- *
- * The caller should then allocate destination memory and copy source memory to
- * it for all those entries (ie with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE
- * flag set).  Once these are allocated and copied, the caller must update each
- * corresponding entry in the dst array with the pfn value of the destination
- * page and with MIGRATE_PFN_VALID. Destination pages must be locked via
- * lock_page().
- *
- * Note that the caller does not have to migrate all the pages that are marked
- * with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration from
- * device memory to system memory.  If the caller cannot migrate a device page
- * back to system memory, then it must return VM_FAULT_SIGBUS, which has severe
- * consequences for the userspace process, so it must be avoided if at all
- * possible.
- *
- * For empty entries inside CPU page table (pte_none() or pmd_none() is true) we
- * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus
- * allowing the caller to allocate device memory for those unbacked virtual
- * addresses.  For this the caller simply has to allocate device memory and
- * properly set the destination entry like for regular migration.  Note that
- * this can still fail, and thus inside the device driver you must check if the
- * migration was successful for those entries after calling migrate_vma_pages(),
- * just like for regular migration.
- *
- * After that, the callers must call migrate_vma_pages() to go over each entry
- * in the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag
- * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set,
- * then migrate_vma_pages() to migrate struct page information from the source
- * struct page to the destination struct page.  If it fails to migrate the
- * struct page information, then it clears the MIGRATE_PFN_MIGRATE flag in the
- * src array.
- *
- * At this point all successfully migrated pages have an entry in the src
- * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst
- * array entry with MIGRATE_PFN_VALID flag set.
- *
- * Once migrate_vma_pages() returns the caller may inspect which pages were
- * successfully migrated, and which were not.  Successfully migrated pages will
- * have the MIGRATE_PFN_MIGRATE flag set for their src array entry.
- *
- * It is safe to update device page table after migrate_vma_pages() because
- * both destination and source page are still locked, and the mmap_lock is held
- * in read mode (hence no one can unmap the range being migrated).
- *
- * Once the caller is done cleaning up things and updating its page table (if it
- * chose to do so, this is not an obligation) it finally calls
- * migrate_vma_finalize() to update the CPU page table to point to new pages
- * for successfully migrated pages or otherwise restore the CPU page table to
- * point to the original source pages.
- */
-int migrate_vma_setup(struct migrate_vma *args)
-{
-	long nr_pages = (args->end - args->start) >> PAGE_SHIFT;
-
-	args->start &= PAGE_MASK;
-	args->end &= PAGE_MASK;
-	if (!args->vma || is_vm_hugetlb_page(args->vma) ||
-	    (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
-		return -EINVAL;
-	if (nr_pages <= 0)
-		return -EINVAL;
-	if (args->start < args->vma->vm_start ||
-	    args->start >= args->vma->vm_end)
-		return -EINVAL;
-	if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end)
-		return -EINVAL;
-	if (!args->src || !args->dst)
-		return -EINVAL;
-
-	memset(args->src, 0, sizeof(*args->src) * nr_pages);
-	args->cpages = 0;
-	args->npages = 0;
-
-	migrate_vma_collect(args);
-
-	if (args->cpages)
-		migrate_vma_unmap(args);
-
-	/*
-	 * At this point pages are locked and unmapped, and thus they have
-	 * stable content and can safely be copied to destination memory that
-	 * is allocated by the drivers.
-	 */
-	return 0;
-
-}
-EXPORT_SYMBOL(migrate_vma_setup);
-
-/*
- * This code closely matches the code in:
- *   __handle_mm_fault()
- *     handle_pte_fault()
- *       do_anonymous_page()
- * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
- * private page.
- */
-static void migrate_vma_insert_page(struct migrate_vma *migrate,
-				    unsigned long addr,
-				    struct page *page,
-				    unsigned long *src)
-{
-	struct vm_area_struct *vma = migrate->vma;
-	struct mm_struct *mm = vma->vm_mm;
-	bool flush = false;
-	spinlock_t *ptl;
-	pte_t entry;
-	pgd_t *pgdp;
-	p4d_t *p4dp;
-	pud_t *pudp;
-	pmd_t *pmdp;
-	pte_t *ptep;
-
-	/* Only allow populating anonymous memory */
-	if (!vma_is_anonymous(vma))
-		goto abort;
-
-	pgdp = pgd_offset(mm, addr);
-	p4dp = p4d_alloc(mm, pgdp, addr);
-	if (!p4dp)
-		goto abort;
-	pudp = pud_alloc(mm, p4dp, addr);
-	if (!pudp)
-		goto abort;
-	pmdp = pmd_alloc(mm, pudp, addr);
-	if (!pmdp)
-		goto abort;
-
-	if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp))
-		goto abort;
-
-	/*
-	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
-	 * pte_offset_map() on pmds where a huge pmd might be created
-	 * from a different thread.
-	 *
-	 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
-	 * parallel threads are excluded by other means.
-	 *
-	 * Here we only have mmap_read_lock(mm).
-	 */
-	if (pte_alloc(mm, pmdp))
-		goto abort;
-
-	/* See the comment in pte_alloc_one_map() */
-	if (unlikely(pmd_trans_unstable(pmdp)))
-		goto abort;
-
-	if (unlikely(anon_vma_prepare(vma)))
-		goto abort;
-	if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
-		goto abort;
-
-	/*
-	 * The memory barrier inside __SetPageUptodate makes sure that
-	 * preceding stores to the page contents become visible before
-	 * the set_pte_at() write.
-	 */
-	__SetPageUptodate(page);
-
-	if (is_device_private_page(page)) {
-		swp_entry_t swp_entry;
-
-		if (vma->vm_flags & VM_WRITE)
-			swp_entry = make_writable_device_private_entry(
-						page_to_pfn(page));
-		else
-			swp_entry = make_readable_device_private_entry(
-						page_to_pfn(page));
-		entry = swp_entry_to_pte(swp_entry);
-	} else {
-		/*
-		 * For now we only support migrating to un-addressable device
-		 * memory.
-		 */
-		if (is_zone_device_page(page)) {
-			pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
-			goto abort;
-		}
-		entry = mk_pte(page, vma->vm_page_prot);
-		if (vma->vm_flags & VM_WRITE)
-			entry = pte_mkwrite(pte_mkdirty(entry));
-	}
-
-	ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
-
-	if (check_stable_address_space(mm))
-		goto unlock_abort;
-
-	if (pte_present(*ptep)) {
-		unsigned long pfn = pte_pfn(*ptep);
-
-		if (!is_zero_pfn(pfn))
-			goto unlock_abort;
-		flush = true;
-	} else if (!pte_none(*ptep))
-		goto unlock_abort;
-
-	/*
-	 * Check for userfaultfd but do not deliver the fault. Instead,
-	 * just back off.
-	 */
-	if (userfaultfd_missing(vma))
-		goto unlock_abort;
-
-	inc_mm_counter(mm, MM_ANONPAGES);
-	page_add_new_anon_rmap(page, vma, addr, false);
-	if (!is_zone_device_page(page))
-		lru_cache_add_inactive_or_unevictable(page, vma);
-	get_page(page);
-
-	if (flush) {
-		flush_cache_page(vma, addr, pte_pfn(*ptep));
-		ptep_clear_flush_notify(vma, addr, ptep);
-		set_pte_at_notify(mm, addr, ptep, entry);
-		update_mmu_cache(vma, addr, ptep);
-	} else {
-		/* No need to invalidate - it was non-present before */
-		set_pte_at(mm, addr, ptep, entry);
-		update_mmu_cache(vma, addr, ptep);
-	}
-
-	pte_unmap_unlock(ptep, ptl);
-	*src = MIGRATE_PFN_MIGRATE;
-	return;
-
-unlock_abort:
-	pte_unmap_unlock(ptep, ptl);
-abort:
-	*src &= ~MIGRATE_PFN_MIGRATE;
-}
-
-/**
- * migrate_vma_pages() - migrate meta-data from src page to dst page
- * @migrate: migrate struct containing all migration information
- *
- * This migrates struct page meta-data from source struct page to destination
- * struct page. This effectively finishes the migration from source page to the
- * destination page.
- */
-void migrate_vma_pages(struct migrate_vma *migrate)
-{
-	const unsigned long npages = migrate->npages;
-	const unsigned long start = migrate->start;
-	struct mmu_notifier_range range;
-	unsigned long addr, i;
-	bool notified = false;
-
-	for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) {
-		struct page *newpage = migrate_pfn_to_page(migrate->dst[i]);
-		struct page *page = migrate_pfn_to_page(migrate->src[i]);
-		struct address_space *mapping;
-		int r;
-
-		if (!newpage) {
-			migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-			continue;
-		}
-
-		if (!page) {
-			if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE))
-				continue;
-			if (!notified) {
-				notified = true;
-
-				mmu_notifier_range_init_owner(&range,
-					MMU_NOTIFY_MIGRATE, 0, migrate->vma,
-					migrate->vma->vm_mm, addr, migrate->end,
-					migrate->pgmap_owner);
-				mmu_notifier_invalidate_range_start(&range);
-			}
-			migrate_vma_insert_page(migrate, addr, newpage,
-						&migrate->src[i]);
-			continue;
-		}
-
-		mapping = page_mapping(page);
-
-		if (is_device_private_page(newpage)) {
-			/*
-			 * For now only support private anonymous when migrating
-			 * to un-addressable device memory.
-			 */
-			if (mapping) {
-				migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-				continue;
-			}
-		} else if (is_zone_device_page(newpage)) {
-			/*
-			 * Other types of ZONE_DEVICE page are not supported.
-			 */
-			migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-			continue;
-		}
-
-		r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY);
-		if (r != MIGRATEPAGE_SUCCESS)
-			migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-	}
-
-	/*
-	 * No need to double call mmu_notifier->invalidate_range() callback as
-	 * the above ptep_clear_flush_notify() inside migrate_vma_insert_page()
-	 * did already call it.
-	 */
-	if (notified)
-		mmu_notifier_invalidate_range_only_end(&range);
-}
-EXPORT_SYMBOL(migrate_vma_pages);
-
-/**
- * migrate_vma_finalize() - restore CPU page table entry
- * @migrate: migrate struct containing all migration information
- *
- * This replaces the special migration pte entry with either a mapping to the
- * new page if migration was successful for that page, or to the original page
- * otherwise.
- *
- * This also unlocks the pages and puts them back on the lru, or drops the extra
- * refcount, for device pages.
- */
-void migrate_vma_finalize(struct migrate_vma *migrate)
-{
-	const unsigned long npages = migrate->npages;
-	unsigned long i;
-
-	for (i = 0; i < npages; i++) {
-		struct page *newpage = migrate_pfn_to_page(migrate->dst[i]);
-		struct page *page = migrate_pfn_to_page(migrate->src[i]);
-
-		if (!page) {
-			if (newpage) {
-				unlock_page(newpage);
-				put_page(newpage);
-			}
-			continue;
-		}
-
-		if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE) || !newpage) {
-			if (newpage) {
-				unlock_page(newpage);
-				put_page(newpage);
-			}
-			newpage = page;
-		}
-
-		remove_migration_ptes(page, newpage, false);
-		unlock_page(page);
-
-		if (is_zone_device_page(page))
-			put_page(page);
-		else
-			putback_lru_page(page);
-
-		if (newpage != page) {
-			unlock_page(newpage);
-			if (is_zone_device_page(newpage))
-				put_page(newpage);
-			else
-				putback_lru_page(newpage);
-		}
-	}
-}
-EXPORT_SYMBOL(migrate_vma_finalize);
-#endif /* CONFIG_DEVICE_PRIVATE */
-
 /*
  * node_demotion[] example:
  *