Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2605 insertions, 0 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
new file mode 100644
index 0000000000..b4d972d80b
--- /dev/null
+++ b/mm/migrate.c
@@ -0,0 +1,2605 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Memory Migration functionality - linux/mm/migrate.c
+ *
+ * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
+ *
+ * Page migration was first developed in the context of the memory hotplug
+ * project. The main authors of the migration code are:
+ *
+ * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
+ * Hirokazu Takahashi <taka@valinux.co.jp>
+ * Dave Hansen <haveblue@us.ibm.com>
+ * Christoph Lameter
+ */
+
+#include <linux/migrate.h>
+#include <linux/export.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>
+#include <linux/mm_inline.h>
+#include <linux/nsproxy.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/topology.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/writeback.h>
+#include <linux/mempolicy.h>
+#include <linux/vmalloc.h>
+#include <linux/security.h>
+#include <linux/backing-dev.h>
+#include <linux/compaction.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <linux/hugetlb.h>
+#include <linux/hugetlb_cgroup.h>
+#include <linux/gfp.h>
+#include <linux/pfn_t.h>
+#include <linux/memremap.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/balloon_compaction.h>
+#include <linux/page_idle.h>
+#include <linux/page_owner.h>
+#include <linux/sched/mm.h>
+#include <linux/ptrace.h>
+#include <linux/oom.h>
+#include <linux/memory.h>
+#include <linux/random.h>
+#include <linux/sched/sysctl.h>
+#include <linux/memory-tiers.h>
+
+#include <asm/tlbflush.h>
+
+#include <trace/events/migrate.h>
+
+#include "internal.h"
+
+bool isolate_movable_page(struct page *page, isolate_mode_t mode)
+{
+	struct folio *folio = folio_get_nontail_page(page);
+	const struct movable_operations *mops;
+
+	/*
+	 * Avoid burning cycles with pages that are yet under __free_pages(),
+	 * or just got freed under us.
+	 *
+	 * In case we 'win' a race for a movable page being freed under us and
+	 * raise its refcount preventing __free_pages() from doing its job
+	 * the put_page() at the end of this block will take care of
+	 * release this page, thus avoiding a nasty leakage.
+	 */
+	if (!folio)
+		goto out;
+
+	if (unlikely(folio_test_slab(folio)))
+		goto out_putfolio;
+	/* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */
+	smp_rmb();
+	/*
+	 * Check movable flag before taking the page lock because
+	 * we use non-atomic bitops on newly allocated page flags so
+	 * unconditionally grabbing the lock ruins page's owner side.
+	 */
+	if (unlikely(!__folio_test_movable(folio)))
+		goto out_putfolio;
+	/* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */
+	smp_rmb();
+	if (unlikely(folio_test_slab(folio)))
+		goto out_putfolio;
+
+	/*
+	 * As movable pages are not isolated from LRU lists, concurrent
+	 * compaction threads can race against page migration functions
+	 * as well as race against the releasing a page.
+	 *
+	 * In order to avoid having an already isolated movable page
+	 * being (wrongly) re-isolated while it is under migration,
+	 * or to avoid attempting to isolate pages being released,
+	 * lets be sure we have the page lock
+	 * before proceeding with the movable page isolation steps.
+	 */
+	if (unlikely(!folio_trylock(folio)))
+		goto out_putfolio;
+
+	if (!folio_test_movable(folio) || folio_test_isolated(folio))
+		goto out_no_isolated;
+
+	mops = folio_movable_ops(folio);
+	VM_BUG_ON_FOLIO(!mops, folio);
+
+	if (!mops->isolate_page(&folio->page, mode))
+		goto out_no_isolated;
+
+	/* Driver shouldn't use PG_isolated bit of page->flags */
+	WARN_ON_ONCE(folio_test_isolated(folio));
+	folio_set_isolated(folio);
+	folio_unlock(folio);
+
+	return true;
+
+out_no_isolated:
+	folio_unlock(folio);
+out_putfolio:
+	folio_put(folio);
+out:
+	return false;
+}
+
+static void putback_movable_folio(struct folio *folio)
+{
+	const struct movable_operations *mops = folio_movable_ops(folio);
+
+	mops->putback_page(&folio->page);
+	folio_clear_isolated(folio);
+}
+
+/*
+ * Put previously isolated pages back onto the appropriate lists
+ * from where they were once taken off for compaction/migration.
+ *
+ * This function shall be used whenever the isolated pageset has been
+ * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
+ * and isolate_hugetlb().
+ */
+void putback_movable_pages(struct list_head *l)
+{
+	struct folio *folio;
+	struct folio *folio2;
+
+	list_for_each_entry_safe(folio, folio2, l, lru) {
+		if (unlikely(folio_test_hugetlb(folio))) {
+			folio_putback_active_hugetlb(folio);
+			continue;
+		}
+		list_del(&folio->lru);
+		/*
+		 * We isolated non-lru movable folio so here we can use
+		 * __PageMovable because LRU folio's mapping cannot have
+		 * PAGE_MAPPING_MOVABLE.
+		 */
+		if (unlikely(__folio_test_movable(folio))) {
+			VM_BUG_ON_FOLIO(!folio_test_isolated(folio), folio);
+			folio_lock(folio);
+			if (folio_test_movable(folio))
+				putback_movable_folio(folio);
+			else
+				folio_clear_isolated(folio);
+			folio_unlock(folio);
+			folio_put(folio);
+		} else {
+			node_stat_mod_folio(folio, NR_ISOLATED_ANON +
+					folio_is_file_lru(folio), -folio_nr_pages(folio));
+			folio_putback_lru(folio);
+		}
+	}
+}
+
+/*
+ * Restore a potential migration pte to a working pte entry
+ */
+static bool remove_migration_pte(struct folio *folio,
+		struct vm_area_struct *vma, unsigned long addr, void *old)
+{
+	DEFINE_FOLIO_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
+
+	while (page_vma_mapped_walk(&pvmw)) {
+		rmap_t rmap_flags = RMAP_NONE;
+		pte_t old_pte;
+		pte_t pte;
+		swp_entry_t entry;
+		struct page *new;
+		unsigned long idx = 0;
+
+		/* pgoff is invalid for ksm pages, but they are never large */
+		if (folio_test_large(folio) && !folio_test_hugetlb(folio))
+			idx = linear_page_index(vma, pvmw.address) - pvmw.pgoff;
+		new = folio_page(folio, idx);
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+		/* PMD-mapped THP migration entry */
+		if (!pvmw.pte) {
+			VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
+					!folio_test_pmd_mappable(folio), folio);
+			remove_migration_pmd(&pvmw, new);
+			continue;
+		}
+#endif
+
+		folio_get(folio);
+		pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
+		old_pte = ptep_get(pvmw.pte);
+		if (pte_swp_soft_dirty(old_pte))
+			pte = pte_mksoft_dirty(pte);
+
+		entry = pte_to_swp_entry(old_pte);
+		if (!is_migration_entry_young(entry))
+			pte = pte_mkold(pte);
+		if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
+			pte = pte_mkdirty(pte);
+		if (is_writable_migration_entry(entry))
+			pte = pte_mkwrite(pte, vma);
+		else if (pte_swp_uffd_wp(old_pte))
+			pte = pte_mkuffd_wp(pte);
+
+		if (folio_test_anon(folio) && !is_readable_migration_entry(entry))
+			rmap_flags |= RMAP_EXCLUSIVE;
+
+		if (unlikely(is_device_private_page(new))) {
+			if (pte_write(pte))
+				entry = make_writable_device_private_entry(
+							page_to_pfn(new));
+			else
+				entry = make_readable_device_private_entry(
+							page_to_pfn(new));
+			pte = swp_entry_to_pte(entry);
+			if (pte_swp_soft_dirty(old_pte))
+				pte = pte_swp_mksoft_dirty(pte);
+			if (pte_swp_uffd_wp(old_pte))
+				pte = pte_swp_mkuffd_wp(pte);
+		}
+
+#ifdef CONFIG_HUGETLB_PAGE
+		if (folio_test_hugetlb(folio)) {
+			struct hstate *h = hstate_vma(vma);
+			unsigned int shift = huge_page_shift(h);
+			unsigned long psize = huge_page_size(h);
+
+			pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
+			if (folio_test_anon(folio))
+				hugepage_add_anon_rmap(new, vma, pvmw.address,
+						       rmap_flags);
+			else
+				page_dup_file_rmap(new, true);
+			set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte,
+					psize);
+		} else
+#endif
+		{
+			if (folio_test_anon(folio))
+				page_add_anon_rmap(new, vma, pvmw.address,
+						   rmap_flags);
+			else
+				page_add_file_rmap(new, vma, false);
+			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
+		}
+		if (vma->vm_flags & VM_LOCKED)
+			mlock_drain_local();
+
+		trace_remove_migration_pte(pvmw.address, pte_val(pte),
+					   compound_order(new));
+
+		/* No need to invalidate - it was non-present before */
+		update_mmu_cache(vma, pvmw.address, pvmw.pte);
+	}
+
+	return true;
+}
+
+/*
+ * Get rid of all migration entries and replace them by
+ * references to the indicated page.
+ */
+void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked)
+{
+	struct rmap_walk_control rwc = {
+		.rmap_one = remove_migration_pte,
+		.arg = src,
+	};
+
+	if (locked)
+		rmap_walk_locked(dst, &rwc);
+	else
+		rmap_walk(dst, &rwc);
+}
+
+/*
+ * Something used the pte of a page under migration. We need to
+ * get to the page and wait until migration is finished.
+ * When we return from this function the fault will be retried.
+ */
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+			  unsigned long address)
+{
+	spinlock_t *ptl;
+	pte_t *ptep;
+	pte_t pte;
+	swp_entry_t entry;
+
+	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (!ptep)
+		return;
+
+	pte = ptep_get(ptep);
+	pte_unmap(ptep);
+
+	if (!is_swap_pte(pte))
+		goto out;
+
+	entry = pte_to_swp_entry(pte);
+	if (!is_migration_entry(entry))
+		goto out;
+
+	migration_entry_wait_on_locked(entry, ptl);
+	return;
+out:
+	spin_unlock(ptl);
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * The vma read lock must be held upon entry. Holding that lock prevents either
+ * the pte or the ptl from being freed.
+ *
+ * This function will release the vma lock before returning.
+ */
+void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *ptep)
+{
+	spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), vma->vm_mm, ptep);
+	pte_t pte;
+
+	hugetlb_vma_assert_locked(vma);
+	spin_lock(ptl);
+	pte = huge_ptep_get(ptep);
+
+	if (unlikely(!is_hugetlb_entry_migration(pte))) {
+		spin_unlock(ptl);
+		hugetlb_vma_unlock_read(vma);
+	} else {
+		/*
+		 * If migration entry existed, safe to release vma lock
+		 * here because the pgtable page won't be freed without the
+		 * pgtable lock released.  See comment right above pgtable
+		 * lock release in migration_entry_wait_on_locked().
+		 */
+		hugetlb_vma_unlock_read(vma);
+		migration_entry_wait_on_locked(pte_to_swp_entry(pte), ptl);
+	}
+}
+#endif
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
+{
+	spinlock_t *ptl;
+
+	ptl = pmd_lock(mm, pmd);
+	if (!is_pmd_migration_entry(*pmd))
+		goto unlock;
+	migration_entry_wait_on_locked(pmd_to_swp_entry(*pmd), ptl);
+	return;
+unlock:
+	spin_unlock(ptl);
+}
+#endif
+
+static int folio_expected_refs(struct address_space *mapping,
+		struct folio *folio)
+{
+	int refs = 1;
+	if (!mapping)
+		return refs;
+
+	refs += folio_nr_pages(folio);
+	if (folio_test_private(folio))
+		refs++;
+
+	return refs;
+}
+
+/*
+ * Replace the page in the mapping.
+ *
+ * The number of remaining references must be:
+ * 1 for anonymous pages without a mapping
+ * 2 for pages with a mapping
+ * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
+ */
+int folio_migrate_mapping(struct address_space *mapping,
+		struct folio *newfolio, struct folio *folio, int extra_count)
+{
+	XA_STATE(xas, &mapping->i_pages, folio_index(folio));
+	struct zone *oldzone, *newzone;
+	int dirty;
+	int expected_count = folio_expected_refs(mapping, folio) + extra_count;
+	long nr = folio_nr_pages(folio);
+	long entries, i;
+
+	if (!mapping) {
+		/* Anonymous page without mapping */
+		if (folio_ref_count(folio) != expected_count)
+			return -EAGAIN;
+
+		/* No turning back from here */
+		newfolio->index = folio->index;
+		newfolio->mapping = folio->mapping;
+		if (folio_test_swapbacked(folio))
+			__folio_set_swapbacked(newfolio);
+
+		return MIGRATEPAGE_SUCCESS;
+	}
+
+	oldzone = folio_zone(folio);
+	newzone = folio_zone(newfolio);
+
+	xas_lock_irq(&xas);
+	if (!folio_ref_freeze(folio, expected_count)) {
+		xas_unlock_irq(&xas);
+		return -EAGAIN;
+	}
+
+	/*
+	 * Now we know that no one else is looking at the folio:
+	 * no turning back from here.
+	 */
+	newfolio->index = folio->index;
+	newfolio->mapping = folio->mapping;
+	folio_ref_add(newfolio, nr); /* add cache reference */
+	if (folio_test_swapbacked(folio)) {
+		__folio_set_swapbacked(newfolio);
+		if (folio_test_swapcache(folio)) {
+			folio_set_swapcache(newfolio);
+			newfolio->private = folio_get_private(folio);
+		}
+		entries = nr;
+	} else {
+		VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
+		entries = 1;
+	}
+
+	/* Move dirty while page refs frozen and newpage not yet exposed */
+	dirty = folio_test_dirty(folio);
+	if (dirty) {
+		folio_clear_dirty(folio);
+		folio_set_dirty(newfolio);
+	}
+
+	/* Swap cache still stores N entries instead of a high-order entry */
+	for (i = 0; i < entries; i++) {
+		xas_store(&xas, newfolio);
+		xas_next(&xas);
+	}
+
+	/*
+	 * Drop cache reference from old page by unfreezing
+	 * to one less reference.
+	 * We know this isn't the last reference.
+	 */
+	folio_ref_unfreeze(folio, expected_count - nr);
+
+	xas_unlock(&xas);
+	/* Leave irq disabled to prevent preemption while updating stats */
+
+	/*
+	 * If moved to a different zone then also account
+	 * the page for that zone. Other VM counters will be
+	 * taken care of when we establish references to the
+	 * new page and drop references to the old page.
+	 *
+	 * Note that anonymous pages are accounted for
+	 * via NR_FILE_PAGES and NR_ANON_MAPPED if they
+	 * are mapped to swap space.
+	 */
+	if (newzone != oldzone) {
+		struct lruvec *old_lruvec, *new_lruvec;
+		struct mem_cgroup *memcg;
+
+		memcg = folio_memcg(folio);
+		old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
+		new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
+
+		__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
+		__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
+		if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
+			__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
+			__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
+
+			if (folio_test_pmd_mappable(folio)) {
+				__mod_lruvec_state(old_lruvec, NR_SHMEM_THPS, -nr);
+				__mod_lruvec_state(new_lruvec, NR_SHMEM_THPS, nr);
+			}
+		}
+#ifdef CONFIG_SWAP
+		if (folio_test_swapcache(folio)) {
+			__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
+			__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
+		}
+#endif
+		if (dirty && mapping_can_writeback(mapping)) {
+			__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
+			__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
+			__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
+			__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
+		}
+	}
+	local_irq_enable();
+
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL(folio_migrate_mapping);
+
+/*
+ * The expected number of remaining references is the same as that
+ * of folio_migrate_mapping().
+ */
+int migrate_huge_page_move_mapping(struct address_space *mapping,
+				   struct folio *dst, struct folio *src)
+{
+	XA_STATE(xas, &mapping->i_pages, folio_index(src));
+	int expected_count;
+
+	xas_lock_irq(&xas);
+	expected_count = 2 + folio_has_private(src);
+	if (!folio_ref_freeze(src, expected_count)) {
+		xas_unlock_irq(&xas);
+		return -EAGAIN;
+	}
+
+	dst->index = src->index;
+	dst->mapping = src->mapping;
+
+	folio_get(dst);
+
+	xas_store(&xas, dst);
+
+	folio_ref_unfreeze(src, expected_count - 1);
+
+	xas_unlock_irq(&xas);
+
+	return MIGRATEPAGE_SUCCESS;
+}
+
+/*
+ * Copy the flags and some other ancillary information
+ */
+void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
+{
+	int cpupid;
+
+	if (folio_test_error(folio))
+		folio_set_error(newfolio);
+	if (folio_test_referenced(folio))
+		folio_set_referenced(newfolio);
+	if (folio_test_uptodate(folio))
+		folio_mark_uptodate(newfolio);
+	if (folio_test_clear_active(folio)) {
+		VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio);
+		folio_set_active(newfolio);
+	} else if (folio_test_clear_unevictable(folio))
+		folio_set_unevictable(newfolio);
+	if (folio_test_workingset(folio))
+		folio_set_workingset(newfolio);
+	if (folio_test_checked(folio))
+		folio_set_checked(newfolio);
+	/*
+	 * PG_anon_exclusive (-> PG_mappedtodisk) is always migrated via
+	 * migration entries. We can still have PG_anon_exclusive set on an
+	 * effectively unmapped and unreferenced first sub-pages of an
+	 * anonymous THP: we can simply copy it here via PG_mappedtodisk.
+	 */
+	if (folio_test_mappedtodisk(folio))
+		folio_set_mappedtodisk(newfolio);
+
+	/* Move dirty on pages not done by folio_migrate_mapping() */
+	if (folio_test_dirty(folio))
+		folio_set_dirty(newfolio);
+
+	if (folio_test_young(folio))
+		folio_set_young(newfolio);
+	if (folio_test_idle(folio))
+		folio_set_idle(newfolio);
+
+	/*
+	 * Copy NUMA information to the new page, to prevent over-eager
+	 * future migrations of this same page.
+	 */
+	cpupid = page_cpupid_xchg_last(&folio->page, -1);
+	/*
+	 * For memory tiering mode, when migrate between slow and fast
+	 * memory node, reset cpupid, because that is used to record
+	 * page access time in slow memory node.
+	 */
+	if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) {
+		bool f_toptier = node_is_toptier(page_to_nid(&folio->page));
+		bool t_toptier = node_is_toptier(page_to_nid(&newfolio->page));
+
+		if (f_toptier != t_toptier)
+			cpupid = -1;
+	}
+	page_cpupid_xchg_last(&newfolio->page, cpupid);
+
+	folio_migrate_ksm(newfolio, folio);
+	/*
+	 * Please do not reorder this without considering how mm/ksm.c's
+	 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
+	 */
+	if (folio_test_swapcache(folio))
+		folio_clear_swapcache(folio);
+	folio_clear_private(folio);
+
+	/* page->private contains hugetlb specific flags */
+	if (!folio_test_hugetlb(folio))
+		folio->private = NULL;
+
+	/*
+	 * If any waiters have accumulated on the new page then
+	 * wake them up.
+	 */
+	if (folio_test_writeback(newfolio))
+		folio_end_writeback(newfolio);
+
+	/*
+	 * PG_readahead shares the same bit with PG_reclaim.  The above
+	 * end_page_writeback() may clear PG_readahead mistakenly, so set the
+	 * bit after that.
+	 */
+	if (folio_test_readahead(folio))
+		folio_set_readahead(newfolio);
+
+	folio_copy_owner(newfolio, folio);
+
+	if (!folio_test_hugetlb(folio))
+		mem_cgroup_migrate(folio, newfolio);
+}
+EXPORT_SYMBOL(folio_migrate_flags);
+
+void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
+{
+	folio_copy(newfolio, folio);
+	folio_migrate_flags(newfolio, folio);
+}
+EXPORT_SYMBOL(folio_migrate_copy);
+
+/************************************************************
+ *                    Migration functions
+ ***********************************************************/
+
+int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
+		struct folio *src, enum migrate_mode mode, int extra_count)
+{
+	int rc;
+
+	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
+
+	rc = folio_migrate_mapping(mapping, dst, src, extra_count);
+
+	if (rc != MIGRATEPAGE_SUCCESS)
+		return rc;
+
+	if (mode != MIGRATE_SYNC_NO_COPY)
+		folio_migrate_copy(dst, src);
+	else
+		folio_migrate_flags(dst, src);
+	return MIGRATEPAGE_SUCCESS;
+}
+
+/**
+ * migrate_folio() - Simple folio migration.
+ * @mapping: The address_space containing the folio.
+ * @dst: The folio to migrate the data to.
+ * @src: The folio containing the current data.
+ * @mode: How to migrate the page.
+ *
+ * Common logic to directly migrate a single LRU folio suitable for
+ * folios that do not use PagePrivate/PagePrivate2.
+ *
+ * Folios are locked upon entry and exit.
+ */
+int migrate_folio(struct address_space *mapping, struct folio *dst,
+		struct folio *src, enum migrate_mode mode)
+{
+	return migrate_folio_extra(mapping, dst, src, mode, 0);
+}
+EXPORT_SYMBOL(migrate_folio);
+
+#ifdef CONFIG_BUFFER_HEAD
+/* Returns true if all buffers are successfully locked */
+static bool buffer_migrate_lock_buffers(struct buffer_head *head,
+							enum migrate_mode mode)
+{
+	struct buffer_head *bh = head;
+	struct buffer_head *failed_bh;
+
+	do {
+		if (!trylock_buffer(bh)) {
+			if (mode == MIGRATE_ASYNC)
+				goto unlock;
+			if (mode == MIGRATE_SYNC_LIGHT && !buffer_uptodate(bh))
+				goto unlock;
+			lock_buffer(bh);
+		}
+
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	return true;
+
+unlock:
+	/* We failed to lock the buffer and cannot stall. */
+	failed_bh = bh;
+	bh = head;
+	while (bh != failed_bh) {
+		unlock_buffer(bh);
+		bh = bh->b_this_page;
+	}
+
+	return false;
+}
+
+static int __buffer_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode,
+		bool check_refs)
+{
+	struct buffer_head *bh, *head;
+	int rc;
+	int expected_count;
+
+	head = folio_buffers(src);
+	if (!head)
+		return migrate_folio(mapping, dst, src, mode);
+
+	/* Check whether page does not have extra refs before we do more work */
+	expected_count = folio_expected_refs(mapping, src);
+	if (folio_ref_count(src) != expected_count)
+		return -EAGAIN;
+
+	if (!buffer_migrate_lock_buffers(head, mode))
+		return -EAGAIN;
+
+	if (check_refs) {
+		bool busy;
+		bool invalidated = false;
+
+recheck_buffers:
+		busy = false;
+		spin_lock(&mapping->private_lock);
+		bh = head;
+		do {
+			if (atomic_read(&bh->b_count)) {
+				busy = true;
+				break;
+			}
+			bh = bh->b_this_page;
+		} while (bh != head);
+		if (busy) {
+			if (invalidated) {
+				rc = -EAGAIN;
+				goto unlock_buffers;
+			}
+			spin_unlock(&mapping->private_lock);
+			invalidate_bh_lrus();
+			invalidated = true;
+			goto recheck_buffers;
+		}
+	}
+
+	rc = folio_migrate_mapping(mapping, dst, src, 0);
+	if (rc != MIGRATEPAGE_SUCCESS)
+		goto unlock_buffers;
+
+	folio_attach_private(dst, folio_detach_private(src));
+
+	bh = head;
+	do {
+		folio_set_bh(bh, dst, bh_offset(bh));
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	if (mode != MIGRATE_SYNC_NO_COPY)
+		folio_migrate_copy(dst, src);
+	else
+		folio_migrate_flags(dst, src);
+
+	rc = MIGRATEPAGE_SUCCESS;
+unlock_buffers:
+	if (check_refs)
+		spin_unlock(&mapping->private_lock);
+	bh = head;
+	do {
+		unlock_buffer(bh);
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	return rc;
+}
+
+/**
+ * buffer_migrate_folio() - Migration function for folios with buffers.
+ * @mapping: The address space containing @src.
+ * @dst: The folio to migrate to.
+ * @src: The folio to migrate from.
+ * @mode: How to migrate the folio.
+ *
+ * This function can only be used if the underlying filesystem guarantees
+ * that no other references to @src exist. For example attached buffer
+ * heads are accessed only under the folio lock.  If your filesystem cannot
+ * provide this guarantee, buffer_migrate_folio_norefs() may be more
+ * appropriate.
+ *
+ * Return: 0 on success or a negative errno on failure.
+ */
+int buffer_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
+{
+	return __buffer_migrate_folio(mapping, dst, src, mode, false);
+}
+EXPORT_SYMBOL(buffer_migrate_folio);
+
+/**
+ * buffer_migrate_folio_norefs() - Migration function for folios with buffers.
+ * @mapping: The address space containing @src.
+ * @dst: The folio to migrate to.
+ * @src: The folio to migrate from.
+ * @mode: How to migrate the folio.
+ *
+ * Like buffer_migrate_folio() except that this variant is more careful
+ * and checks that there are also no buffer head references. This function
+ * is the right one for mappings where buffer heads are directly looked
+ * up and referenced (such as block device mappings).
+ *
+ * Return: 0 on success or a negative errno on failure.
+ */
+int buffer_migrate_folio_norefs(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
+{
+	return __buffer_migrate_folio(mapping, dst, src, mode, true);
+}
+EXPORT_SYMBOL_GPL(buffer_migrate_folio_norefs);
+#endif /* CONFIG_BUFFER_HEAD */
+
+int filemap_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
+{
+	int ret;
+
+	ret = folio_migrate_mapping(mapping, dst, src, 0);
+	if (ret != MIGRATEPAGE_SUCCESS)
+		return ret;
+
+	if (folio_get_private(src))
+		folio_attach_private(dst, folio_detach_private(src));
+
+	if (mode != MIGRATE_SYNC_NO_COPY)
+		folio_migrate_copy(dst, src);
+	else
+		folio_migrate_flags(dst, src);
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(filemap_migrate_folio);
+
+/*
+ * Writeback a folio to clean the dirty state
+ */
+static int writeout(struct address_space *mapping, struct folio *folio)
+{
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE,
+		.nr_to_write = 1,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+		.for_reclaim = 1
+	};
+	int rc;
+
+	if (!mapping->a_ops->writepage)
+		/* No write method for the address space */
+		return -EINVAL;
+
+	if (!folio_clear_dirty_for_io(folio))
+		/* Someone else already triggered a write */
+		return -EAGAIN;
+
+	/*
+	 * A dirty folio may imply that the underlying filesystem has
+	 * the folio on some queue. So the folio must be clean for
+	 * migration. Writeout may mean we lose the lock and the
+	 * folio state is no longer what we checked for earlier.
+	 * At this point we know that the migration attempt cannot
+	 * be successful.
+	 */
+	remove_migration_ptes(folio, folio, false);
+
+	rc = mapping->a_ops->writepage(&folio->page, &wbc);
+
+	if (rc != AOP_WRITEPAGE_ACTIVATE)
+		/* unlocked. Relock */
+		folio_lock(folio);
+
+	return (rc < 0) ? -EIO : -EAGAIN;
+}
+
+/*
+ * Default handling if a filesystem does not provide a migration function.
+ */
+static int fallback_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
+{
+	if (folio_test_dirty(src)) {
+		/* Only writeback folios in full synchronous migration */
+		switch (mode) {
+		case MIGRATE_SYNC:
+		case MIGRATE_SYNC_NO_COPY:
+			break;
+		default:
+			return -EBUSY;
+		}
+		return writeout(mapping, src);
+	}
+
+	/*
+	 * Buffers may be managed in a filesystem specific way.
+	 * We must have no buffers or drop them.
+	 */
+	if (!filemap_release_folio(src, GFP_KERNEL))
+		return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
+
+	return migrate_folio(mapping, dst, src, mode);
+}
+
+/*
+ * Move a page to a newly allocated page
+ * The page is locked and all ptes have been successfully removed.
+ *
+ * The new page will have replaced the old page if this function
+ * is successful.
+ *
+ * Return value:
+ *   < 0 - error code
+ *  MIGRATEPAGE_SUCCESS - success
+ */
+static int move_to_new_folio(struct folio *dst, struct folio *src,
+				enum migrate_mode mode)
+{
+	int rc = -EAGAIN;
+	bool is_lru = !__PageMovable(&src->page);
+
+	VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
+	VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
+
+	if (likely(is_lru)) {
+		struct address_space *mapping = folio_mapping(src);
+
+		if (!mapping)
+			rc = migrate_folio(mapping, dst, src, mode);
+		else if (mapping->a_ops->migrate_folio)
+			/*
+			 * Most folios have a mapping and most filesystems
+			 * provide a migrate_folio callback. Anonymous folios
+			 * are part of swap space which also has its own
+			 * migrate_folio callback. This is the most common path
+			 * for page migration.
+			 */
+			rc = mapping->a_ops->migrate_folio(mapping, dst, src,
+								mode);
+		else
+			rc = fallback_migrate_folio(mapping, dst, src, mode);
+	} else {
+		const struct movable_operations *mops;
+
+		/*
+		 * In case of non-lru page, it could be released after
+		 * isolation step. In that case, we shouldn't try migration.
+		 */
+		VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
+		if (!folio_test_movable(src)) {
+			rc = MIGRATEPAGE_SUCCESS;
+			folio_clear_isolated(src);
+			goto out;
+		}
+
+		mops = folio_movable_ops(src);
+		rc = mops->migrate_page(&dst->page, &src->page, mode);
+		WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
+				!folio_test_isolated(src));
+	}
+
+	/*
+	 * When successful, old pagecache src->mapping must be cleared before
+	 * src is freed; but stats require that PageAnon be left as PageAnon.
+	 */
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		if (__PageMovable(&src->page)) {
+			VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
+
+			/*
+			 * We clear PG_movable under page_lock so any compactor
+			 * cannot try to migrate this page.
+			 */
+			folio_clear_isolated(src);
+		}
+
+		/*
+		 * Anonymous and movable src->mapping will be cleared by
+		 * free_pages_prepare so don't reset it here for keeping
+		 * the type to work PageAnon, for example.
+		 */
+		if (!folio_mapping_flags(src))
+			src->mapping = NULL;
+
+		if (likely(!folio_is_zone_device(dst)))
+			flush_dcache_folio(dst);
+	}
+out:
+	return rc;
+}
+
+/*
+ * To record some information during migration, we use unused private
+ * field of struct folio of the newly allocated destination folio.
+ * This is safe because nobody is using it except us.
+ */
+enum {
+	PAGE_WAS_MAPPED = BIT(0),
+	PAGE_WAS_MLOCKED = BIT(1),
+	PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
+};
+
+static void __migrate_folio_record(struct folio *dst,
+				   int old_page_state,
+				   struct anon_vma *anon_vma)
+{
+	dst->private = (void *)anon_vma + old_page_state;
+}
+
+static void __migrate_folio_extract(struct folio *dst,
+				   int *old_page_state,
+				   struct anon_vma **anon_vmap)
+{
+	unsigned long private = (unsigned long)dst->private;
+
+	*anon_vmap = (struct anon_vma *)(private & ~PAGE_OLD_STATES);
+	*old_page_state = private & PAGE_OLD_STATES;
+	dst->private = NULL;
+}
+
+/* Restore the source folio to the original state upon failure */
+static void migrate_folio_undo_src(struct folio *src,
+				   int page_was_mapped,
+				   struct anon_vma *anon_vma,
+				   bool locked,
+				   struct list_head *ret)
+{
+	if (page_was_mapped)
+		remove_migration_ptes(src, src, false);
+	/* Drop an anon_vma reference if we took one */
+	if (anon_vma)
+		put_anon_vma(anon_vma);
+	if (locked)
+		folio_unlock(src);
+	if (ret)
+		list_move_tail(&src->lru, ret);
+}
+
+/* Restore the destination folio to the original state upon failure */
+static void migrate_folio_undo_dst(struct folio *dst, bool locked,
+		free_folio_t put_new_folio, unsigned long private)
+{
+	if (locked)
+		folio_unlock(dst);
+	if (put_new_folio)
+		put_new_folio(dst, private);
+	else
+		folio_put(dst);
+}
+
+/* Cleanup src folio upon migration success */
+static void migrate_folio_done(struct folio *src,
+			       enum migrate_reason reason)
+{
+	/*
+	 * Compaction can migrate also non-LRU pages which are
+	 * not accounted to NR_ISOLATED_*. They can be recognized
+	 * as __PageMovable
+	 */
+	if (likely(!__folio_test_movable(src)))
+		mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
+				    folio_is_file_lru(src), -folio_nr_pages(src));
+
+	if (reason != MR_MEMORY_FAILURE)
+		/* We release the page in page_handle_poison. */
+		folio_put(src);
+}
+
+/* Obtain the lock on page, remove all ptes. */
+static int migrate_folio_unmap(new_folio_t get_new_folio,
+		free_folio_t put_new_folio, unsigned long private,
+		struct folio *src, struct folio **dstp, enum migrate_mode mode,
+		enum migrate_reason reason, struct list_head *ret)
+{
+	struct folio *dst;
+	int rc = -EAGAIN;
+	int old_page_state = 0;
+	struct anon_vma *anon_vma = NULL;
+	bool is_lru = !__PageMovable(&src->page);
+	bool locked = false;
+	bool dst_locked = false;
+
+	if (folio_ref_count(src) == 1) {
+		/* Folio was freed from under us. So we are done. */
+		folio_clear_active(src);
+		folio_clear_unevictable(src);
+		/* free_pages_prepare() will clear PG_isolated. */
+		list_del(&src->lru);
+		migrate_folio_done(src, reason);
+		return MIGRATEPAGE_SUCCESS;
+	}
+
+	dst = get_new_folio(src, private);
+	if (!dst)
+		return -ENOMEM;
+	*dstp = dst;
+
+	dst->private = NULL;
+
+	if (!folio_trylock(src)) {
+		if (mode == MIGRATE_ASYNC)
+			goto out;
+
+		/*
+		 * It's not safe for direct compaction to call lock_page.
+		 * For example, during page readahead pages are added locked
+		 * to the LRU. Later, when the IO completes the pages are
+		 * marked uptodate and unlocked. However, the queueing
+		 * could be merging multiple pages for one bio (e.g.
+		 * mpage_readahead). If an allocation happens for the
+		 * second or third page, the process can end up locking
+		 * the same page twice and deadlocking. Rather than
+		 * trying to be clever about what pages can be locked,
+		 * avoid the use of lock_page for direct compaction
+		 * altogether.
+		 */
+		if (current->flags & PF_MEMALLOC)
+			goto out;
+
+		/*
+		 * In "light" mode, we can wait for transient locks (eg
+		 * inserting a page into the page table), but it's not
+		 * worth waiting for I/O.
+		 */
+		if (mode == MIGRATE_SYNC_LIGHT && !folio_test_uptodate(src))
+			goto out;
+
+		folio_lock(src);
+	}
+	locked = true;
+	if (folio_test_mlocked(src))
+		old_page_state |= PAGE_WAS_MLOCKED;
+
+	if (folio_test_writeback(src)) {
+		/*
+		 * Only in the case of a full synchronous migration is it
+		 * necessary to wait for PageWriteback. In the async case,
+		 * the retry loop is too short and in the sync-light case,
+		 * the overhead of stalling is too much
+		 */
+		switch (mode) {
+		case MIGRATE_SYNC:
+		case MIGRATE_SYNC_NO_COPY:
+			break;
+		default:
+			rc = -EBUSY;
+			goto out;
+		}
+		folio_wait_writeback(src);
+	}
+
+	/*
+	 * By try_to_migrate(), src->mapcount goes down to 0 here. In this case,
+	 * we cannot notice that anon_vma is freed while we migrate a page.
+	 * This get_anon_vma() delays freeing anon_vma pointer until the end
+	 * of migration. File cache pages are no problem because of page_lock()
+	 * File Caches may use write_page() or lock_page() in migration, then,
+	 * just care Anon page here.
+	 *
+	 * Only folio_get_anon_vma() understands the subtleties of
+	 * getting a hold on an anon_vma from outside one of its mms.
+	 * But if we cannot get anon_vma, then we won't need it anyway,
+	 * because that implies that the anon page is no longer mapped
+	 * (and cannot be remapped so long as we hold the page lock).
+	 */
+	if (folio_test_anon(src) && !folio_test_ksm(src))
+		anon_vma = folio_get_anon_vma(src);
+
+	/*
+	 * Block others from accessing the new page when we get around to
+	 * establishing additional references. We are usually the only one
+	 * holding a reference to dst at this point. We used to have a BUG
+	 * here if folio_trylock(dst) fails, but would like to allow for
+	 * cases where there might be a race with the previous use of dst.
+	 * This is much like races on refcount of oldpage: just don't BUG().
+	 */
+	if (unlikely(!folio_trylock(dst)))
+		goto out;
+	dst_locked = true;
+
+	if (unlikely(!is_lru)) {
+		__migrate_folio_record(dst, old_page_state, anon_vma);
+		return MIGRATEPAGE_UNMAP;
+	}
+
+	/*
+	 * Corner case handling:
+	 * 1. When a new swap-cache page is read into, it is added to the LRU
+	 * and treated as swapcache but it has no rmap yet.
+	 * Calling try_to_unmap() against a src->mapping==NULL page will
+	 * trigger a BUG.  So handle it here.
+	 * 2. An orphaned page (see truncate_cleanup_page) might have
+	 * fs-private metadata. The page can be picked up due to memory
+	 * offlining.  Everywhere else except page reclaim, the page is
+	 * invisible to the vm, so the page can not be migrated.  So try to
+	 * free the metadata, so the page can be freed.
+	 */
+	if (!src->mapping) {
+		if (folio_test_private(src)) {
+			try_to_free_buffers(src);
+			goto out;
+		}
+	} else if (folio_mapped(src)) {
+		/* Establish migration ptes */
+		VM_BUG_ON_FOLIO(folio_test_anon(src) &&
+			       !folio_test_ksm(src) && !anon_vma, src);
+		try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
+		old_page_state |= PAGE_WAS_MAPPED;
+	}
+
+	if (!folio_mapped(src)) {
+		__migrate_folio_record(dst, old_page_state, anon_vma);
+		return MIGRATEPAGE_UNMAP;
+	}
+
+out:
+	/*
+	 * A folio that has not been unmapped will be restored to
+	 * right list unless we want to retry.
+	 */
+	if (rc == -EAGAIN)
+		ret = NULL;
+
+	migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
+			       anon_vma, locked, ret);
+	migrate_folio_undo_dst(dst, dst_locked, put_new_folio, private);
+
+	return rc;
+}
+
+/* Migrate the folio to the newly allocated folio in dst. */
+static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
+			      struct folio *src, struct folio *dst,
+			      enum migrate_mode mode, enum migrate_reason reason,
+			      struct list_head *ret)
+{
+	int rc;
+	int old_page_state = 0;
+	struct anon_vma *anon_vma = NULL;
+	bool is_lru = !__PageMovable(&src->page);
+	struct list_head *prev;
+
+	__migrate_folio_extract(dst, &old_page_state, &anon_vma);
+	prev = dst->lru.prev;
+	list_del(&dst->lru);
+
+	rc = move_to_new_folio(dst, src, mode);
+	if (rc)
+		goto out;
+
+	if (unlikely(!is_lru))
+		goto out_unlock_both;
+
+	/*
+	 * When successful, push dst to LRU immediately: so that if it
+	 * turns out to be an mlocked page, remove_migration_ptes() will
+	 * automatically build up the correct dst->mlock_count for it.
+	 *
+	 * We would like to do something similar for the old page, when
+	 * unsuccessful, and other cases when a page has been temporarily
+	 * isolated from the unevictable LRU: but this case is the easiest.
+	 */
+	folio_add_lru(dst);
+	if (old_page_state & PAGE_WAS_MLOCKED)
+		lru_add_drain();
+
+	if (old_page_state & PAGE_WAS_MAPPED)
+		remove_migration_ptes(src, dst, false);
+
+out_unlock_both:
+	folio_unlock(dst);
+	set_page_owner_migrate_reason(&dst->page, reason);
+	/*
+	 * If migration is successful, decrease refcount of dst,
+	 * which will not free the page because new page owner increased
+	 * refcounter.
+	 */
+	folio_put(dst);
+
+	/*
+	 * A folio that has been migrated has all references removed
+	 * and will be freed.
+	 */
+	list_del(&src->lru);
+	/* Drop an anon_vma reference if we took one */
+	if (anon_vma)
+		put_anon_vma(anon_vma);
+	folio_unlock(src);
+	migrate_folio_done(src, reason);
+
+	return rc;
+out:
+	/*
+	 * A folio that has not been migrated will be restored to
+	 * right list unless we want to retry.
+	 */
+	if (rc == -EAGAIN) {
+		list_add(&dst->lru, prev);
+		__migrate_folio_record(dst, old_page_state, anon_vma);
+		return rc;
+	}
+
+	migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
+			       anon_vma, true, ret);
+	migrate_folio_undo_dst(dst, true, put_new_folio, private);
+
+	return rc;
+}
+
+/*
+ * Counterpart of unmap_and_move_page() for hugepage migration.
+ *
+ * This function doesn't wait the completion of hugepage I/O
+ * because there is no race between I/O and migration for hugepage.
+ * Note that currently hugepage I/O occurs only in direct I/O
+ * where no lock is held and PG_writeback is irrelevant,
+ * and writeback status of all subpages are counted in the reference
+ * count of the head page (i.e. if all subpages of a 2MB hugepage are
+ * under direct I/O, the reference of the head page is 512 and a bit more.)
+ * This means that when we try to migrate hugepage whose subpages are
+ * doing direct I/O, some references remain after try_to_unmap() and
+ * hugepage migration fails without data corruption.
+ *
+ * There is also no race when direct I/O is issued on the page under migration,
+ * because then pte is replaced with migration swap entry and direct I/O code
+ * will wait in the page fault for migration to complete.
+ */
+static int unmap_and_move_huge_page(new_folio_t get_new_folio,
+		free_folio_t put_new_folio, unsigned long private,
+		struct folio *src, int force, enum migrate_mode mode,
+		int reason, struct list_head *ret)
+{
+	struct folio *dst;
+	int rc = -EAGAIN;
+	int page_was_mapped = 0;
+	struct anon_vma *anon_vma = NULL;
+	struct address_space *mapping = NULL;
+
+	if (folio_ref_count(src) == 1) {
+		/* page was freed from under us. So we are done. */
+		folio_putback_active_hugetlb(src);
+		return MIGRATEPAGE_SUCCESS;
+	}
+
+	dst = get_new_folio(src, private);
+	if (!dst)
+		return -ENOMEM;
+
+	if (!folio_trylock(src)) {
+		if (!force)
+			goto out;
+		switch (mode) {
+		case MIGRATE_SYNC:
+		case MIGRATE_SYNC_NO_COPY:
+			break;
+		default:
+			goto out;
+		}
+		folio_lock(src);
+	}
+
+	/*
+	 * Check for pages which are in the process of being freed.  Without
+	 * folio_mapping() set, hugetlbfs specific move page routine will not
+	 * be called and we could leak usage counts for subpools.
+	 */
+	if (hugetlb_folio_subpool(src) && !folio_mapping(src)) {
+		rc = -EBUSY;
+		goto out_unlock;
+	}
+
+	if (folio_test_anon(src))
+		anon_vma = folio_get_anon_vma(src);
+
+	if (unlikely(!folio_trylock(dst)))
+		goto put_anon;
+
+	if (folio_mapped(src)) {
+		enum ttu_flags ttu = 0;
+
+		if (!folio_test_anon(src)) {
+			/*
+			 * In shared mappings, try_to_unmap could potentially
+			 * call huge_pmd_unshare.  Because of this, take
+			 * semaphore in write mode here and set TTU_RMAP_LOCKED
+			 * to let lower levels know we have taken the lock.
+			 */
+			mapping = hugetlb_page_mapping_lock_write(&src->page);
+			if (unlikely(!mapping))
+				goto unlock_put_anon;
+
+			ttu = TTU_RMAP_LOCKED;
+		}
+
+		try_to_migrate(src, ttu);
+		page_was_mapped = 1;
+
+		if (ttu & TTU_RMAP_LOCKED)
+			i_mmap_unlock_write(mapping);
+	}
+
+	if (!folio_mapped(src))
+		rc = move_to_new_folio(dst, src, mode);
+
+	if (page_was_mapped)
+		remove_migration_ptes(src,
+			rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
+
+unlock_put_anon:
+	folio_unlock(dst);
+
+put_anon:
+	if (anon_vma)
+		put_anon_vma(anon_vma);
+
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		move_hugetlb_state(src, dst, reason);
+		put_new_folio = NULL;
+	}
+
+out_unlock:
+	folio_unlock(src);
+out:
+	if (rc == MIGRATEPAGE_SUCCESS)
+		folio_putback_active_hugetlb(src);
+	else if (rc != -EAGAIN)
+		list_move_tail(&src->lru, ret);
+
+	/*
+	 * If migration was not successful and there's a freeing callback, use
+	 * it.  Otherwise, put_page() will drop the reference grabbed during
+	 * isolation.
+	 */
+	if (put_new_folio)
+		put_new_folio(dst, private);
+	else
+		folio_putback_active_hugetlb(dst);
+
+	return rc;
+}
+
+static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
+{
+	int rc;
+
+	folio_lock(folio);
+	rc = split_folio_to_list(folio, split_folios);
+	folio_unlock(folio);
+	if (!rc)
+		list_move_tail(&folio->lru, split_folios);
+
+	return rc;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define NR_MAX_BATCHED_MIGRATION	HPAGE_PMD_NR
+#else
+#define NR_MAX_BATCHED_MIGRATION	512
+#endif
+#define NR_MAX_MIGRATE_PAGES_RETRY	10
+#define NR_MAX_MIGRATE_ASYNC_RETRY	3
+#define NR_MAX_MIGRATE_SYNC_RETRY					\
+	(NR_MAX_MIGRATE_PAGES_RETRY - NR_MAX_MIGRATE_ASYNC_RETRY)
+
+struct migrate_pages_stats {
+	int nr_succeeded;	/* Normal and large folios migrated successfully, in
+				   units of base pages */
+	int nr_failed_pages;	/* Normal and large folios failed to be migrated, in
+				   units of base pages.  Untried folios aren't counted */
+	int nr_thp_succeeded;	/* THP migrated successfully */
+	int nr_thp_failed;	/* THP failed to be migrated */
+	int nr_thp_split;	/* THP split before migrating */
+};
+
+/*
+ * Returns the number of hugetlb folios that were not migrated, or an error code
+ * after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no hugetlb folios are movable
+ * any more because the list has become empty or no retryable hugetlb folios
+ * exist any more. It is caller's responsibility to call putback_movable_pages()
+ * only if ret != 0.
+ */
+static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
+			    free_folio_t put_new_folio, unsigned long private,
+			    enum migrate_mode mode, int reason,
+			    struct migrate_pages_stats *stats,
+			    struct list_head *ret_folios)
+{
+	int retry = 1;
+	int nr_failed = 0;
+	int nr_retry_pages = 0;
+	int pass = 0;
+	struct folio *folio, *folio2;
+	int rc, nr_pages;
+
+	for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && retry; pass++) {
+		retry = 0;
+		nr_retry_pages = 0;
+
+		list_for_each_entry_safe(folio, folio2, from, lru) {
+			if (!folio_test_hugetlb(folio))
+				continue;
+
+			nr_pages = folio_nr_pages(folio);
+
+			cond_resched();
+
+			/*
+			 * Migratability of hugepages depends on architectures and
+			 * their size.  This check is necessary because some callers
+			 * of hugepage migration like soft offline and memory
+			 * hotremove don't walk through page tables or check whether
+			 * the hugepage is pmd-based or not before kicking migration.
+			 */
+			if (!hugepage_migration_supported(folio_hstate(folio))) {
+				nr_failed++;
+				stats->nr_failed_pages += nr_pages;
+				list_move_tail(&folio->lru, ret_folios);
+				continue;
+			}
+
+			rc = unmap_and_move_huge_page(get_new_folio,
+						      put_new_folio, private,
+						      folio, pass > 2, mode,
+						      reason, ret_folios);
+			/*
+			 * The rules are:
+			 *	Success: hugetlb folio will be put back
+			 *	-EAGAIN: stay on the from list
+			 *	-ENOMEM: stay on the from list
+			 *	Other errno: put on ret_folios list
+			 */
+			switch(rc) {
+			case -ENOMEM:
+				/*
+				 * When memory is low, don't bother to try to migrate
+				 * other folios, just exit.
+				 */
+				stats->nr_failed_pages += nr_pages + nr_retry_pages;
+				return -ENOMEM;
+			case -EAGAIN:
+				retry++;
+				nr_retry_pages += nr_pages;
+				break;
+			case MIGRATEPAGE_SUCCESS:
+				stats->nr_succeeded += nr_pages;
+				break;
+			default:
+				/*
+				 * Permanent failure (-EBUSY, etc.):
+				 * unlike -EAGAIN case, the failed folio is
+				 * removed from migration folio list and not
+				 * retried in the next outer loop.
+				 */
+				nr_failed++;
+				stats->nr_failed_pages += nr_pages;
+				break;
+			}
+		}
+	}
+	/*
+	 * nr_failed is number of hugetlb folios failed to be migrated.  After
+	 * NR_MAX_MIGRATE_PAGES_RETRY attempts, give up and count retried hugetlb
+	 * folios as failed.
+	 */
+	nr_failed += retry;
+	stats->nr_failed_pages += nr_retry_pages;
+
+	return nr_failed;
+}
+
+/*
+ * migrate_pages_batch() first unmaps folios in the from list as many as
+ * possible, then move the unmapped folios.
+ *
+ * We only batch migration if mode == MIGRATE_ASYNC to avoid to wait a
+ * lock or bit when we have locked more than one folio.  Which may cause
+ * deadlock (e.g., for loop device).  So, if mode != MIGRATE_ASYNC, the
+ * length of the from list must be <= 1.
+ */
+static int migrate_pages_batch(struct list_head *from,
+		new_folio_t get_new_folio, free_folio_t put_new_folio,
+		unsigned long private, enum migrate_mode mode, int reason,
+		struct list_head *ret_folios, struct list_head *split_folios,
+		struct migrate_pages_stats *stats, int nr_pass)
+{
+	int retry = 1;
+	int thp_retry = 1;
+	int nr_failed = 0;
+	int nr_retry_pages = 0;
+	int pass = 0;
+	bool is_thp = false;
+	struct folio *folio, *folio2, *dst = NULL, *dst2;
+	int rc, rc_saved = 0, nr_pages;
+	LIST_HEAD(unmap_folios);
+	LIST_HEAD(dst_folios);
+	bool nosplit = (reason == MR_NUMA_MISPLACED);
+
+	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
+			!list_empty(from) && !list_is_singular(from));
+
+	for (pass = 0; pass < nr_pass && retry; pass++) {
+		retry = 0;
+		thp_retry = 0;
+		nr_retry_pages = 0;
+
+		list_for_each_entry_safe(folio, folio2, from, lru) {
+			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
+			nr_pages = folio_nr_pages(folio);
+
+			cond_resched();
+
+			/*
+			 * Large folio migration might be unsupported or
+			 * the allocation might be failed so we should retry
+			 * on the same folio with the large folio split
+			 * to normal folios.
+			 *
+			 * Split folios are put in split_folios, and
+			 * we will migrate them after the rest of the
+			 * list is processed.
+			 */
+			if (!thp_migration_supported() && is_thp) {
+				nr_failed++;
+				stats->nr_thp_failed++;
+				if (!try_split_folio(folio, split_folios)) {
+					stats->nr_thp_split++;
+					continue;
+				}
+				stats->nr_failed_pages += nr_pages;
+				list_move_tail(&folio->lru, ret_folios);
+				continue;
+			}
+
+			rc = migrate_folio_unmap(get_new_folio, put_new_folio,
+					private, folio, &dst, mode, reason,
+					ret_folios);
+			/*
+			 * The rules are:
+			 *	Success: folio will be freed
+			 *	Unmap: folio will be put on unmap_folios list,
+			 *	       dst folio put on dst_folios list
+			 *	-EAGAIN: stay on the from list
+			 *	-ENOMEM: stay on the from list
+			 *	Other errno: put on ret_folios list
+			 */
+			switch(rc) {
+			case -ENOMEM:
+				/*
+				 * When memory is low, don't bother to try to migrate
+				 * other folios, move unmapped folios, then exit.
+				 */
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
+				/* Large folio NUMA faulting doesn't split to retry. */
+				if (folio_test_large(folio) && !nosplit) {
+					int ret = try_split_folio(folio, split_folios);
+
+					if (!ret) {
+						stats->nr_thp_split += is_thp;
+						break;
+					} else if (reason == MR_LONGTERM_PIN &&
+						   ret == -EAGAIN) {
+						/*
+						 * Try again to split large folio to
+						 * mitigate the failure of longterm pinning.
+						 */
+						retry++;
+						thp_retry += is_thp;
+						nr_retry_pages += nr_pages;
+						/* Undo duplicated failure counting. */
+						nr_failed--;
+						stats->nr_thp_failed -= is_thp;
+						break;
+					}
+				}
+
+				stats->nr_failed_pages += nr_pages + nr_retry_pages;
+				/* nr_failed isn't updated for not used */
+				stats->nr_thp_failed += thp_retry;
+				rc_saved = rc;
+				if (list_empty(&unmap_folios))
+					goto out;
+				else
+					goto move;
+			case -EAGAIN:
+				retry++;
+				thp_retry += is_thp;
+				nr_retry_pages += nr_pages;
+				break;
+			case MIGRATEPAGE_SUCCESS:
+				stats->nr_succeeded += nr_pages;
+				stats->nr_thp_succeeded += is_thp;
+				break;
+			case MIGRATEPAGE_UNMAP:
+				list_move_tail(&folio->lru, &unmap_folios);
+				list_add_tail(&dst->lru, &dst_folios);
+				break;
+			default:
+				/*
+				 * Permanent failure (-EBUSY, etc.):
+				 * unlike -EAGAIN case, the failed folio is
+				 * removed from migration folio list and not
+				 * retried in the next outer loop.
+				 */
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
+				stats->nr_failed_pages += nr_pages;
+				break;
+			}
+		}
+	}
+	nr_failed += retry;
+	stats->nr_thp_failed += thp_retry;
+	stats->nr_failed_pages += nr_retry_pages;
+move:
+	/* Flush TLBs for all unmapped folios */
+	try_to_unmap_flush();
+
+	retry = 1;
+	for (pass = 0; pass < nr_pass && retry; pass++) {
+		retry = 0;
+		thp_retry = 0;
+		nr_retry_pages = 0;
+
+		dst = list_first_entry(&dst_folios, struct folio, lru);
+		dst2 = list_next_entry(dst, lru);
+		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
+			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
+			nr_pages = folio_nr_pages(folio);
+
+			cond_resched();
+
+			rc = migrate_folio_move(put_new_folio, private,
+						folio, dst, mode,
+						reason, ret_folios);
+			/*
+			 * The rules are:
+			 *	Success: folio will be freed
+			 *	-EAGAIN: stay on the unmap_folios list
+			 *	Other errno: put on ret_folios list
+			 */
+			switch(rc) {
+			case -EAGAIN:
+				retry++;
+				thp_retry += is_thp;
+				nr_retry_pages += nr_pages;
+				break;
+			case MIGRATEPAGE_SUCCESS:
+				stats->nr_succeeded += nr_pages;
+				stats->nr_thp_succeeded += is_thp;
+				break;
+			default:
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
+				stats->nr_failed_pages += nr_pages;
+				break;
+			}
+			dst = dst2;
+			dst2 = list_next_entry(dst, lru);
+		}
+	}
+	nr_failed += retry;
+	stats->nr_thp_failed += thp_retry;
+	stats->nr_failed_pages += nr_retry_pages;
+
+	rc = rc_saved ? : nr_failed;
+out:
+	/* Cleanup remaining folios */
+	dst = list_first_entry(&dst_folios, struct folio, lru);
+	dst2 = list_next_entry(dst, lru);
+	list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
+		int old_page_state = 0;
+		struct anon_vma *anon_vma = NULL;
+
+		__migrate_folio_extract(dst, &old_page_state, &anon_vma);
+		migrate_folio_undo_src(folio, old_page_state & PAGE_WAS_MAPPED,
+				       anon_vma, true, ret_folios);
+		list_del(&dst->lru);
+		migrate_folio_undo_dst(dst, true, put_new_folio, private);
+		dst = dst2;
+		dst2 = list_next_entry(dst, lru);
+	}
+
+	return rc;
+}
+
+static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio,
+		free_folio_t put_new_folio, unsigned long private,
+		enum migrate_mode mode, int reason,
+		struct list_head *ret_folios, struct list_head *split_folios,
+		struct migrate_pages_stats *stats)
+{
+	int rc, nr_failed = 0;
+	LIST_HEAD(folios);
+	struct migrate_pages_stats astats;
+
+	memset(&astats, 0, sizeof(astats));
+	/* Try to migrate in batch with MIGRATE_ASYNC mode firstly */
+	rc = migrate_pages_batch(from, get_new_folio, put_new_folio, private, MIGRATE_ASYNC,
+				 reason, &folios, split_folios, &astats,
+				 NR_MAX_MIGRATE_ASYNC_RETRY);
+	stats->nr_succeeded += astats.nr_succeeded;
+	stats->nr_thp_succeeded += astats.nr_thp_succeeded;
+	stats->nr_thp_split += astats.nr_thp_split;
+	if (rc < 0) {
+		stats->nr_failed_pages += astats.nr_failed_pages;
+		stats->nr_thp_failed += astats.nr_thp_failed;
+		list_splice_tail(&folios, ret_folios);
+		return rc;
+	}
+	stats->nr_thp_failed += astats.nr_thp_split;
+	nr_failed += astats.nr_thp_split;
+	/*
+	 * Fall back to migrate all failed folios one by one synchronously. All
+	 * failed folios except split THPs will be retried, so their failure
+	 * isn't counted
+	 */
+	list_splice_tail_init(&folios, from);
+	while (!list_empty(from)) {
+		list_move(from->next, &folios);
+		rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,
+					 private, mode, reason, ret_folios,
+					 split_folios, stats, NR_MAX_MIGRATE_SYNC_RETRY);
+		list_splice_tail_init(&folios, ret_folios);
+		if (rc < 0)
+			return rc;
+		nr_failed += rc;
+	}
+
+	return nr_failed;
+}
+
+/*
+ * migrate_pages - migrate the folios specified in a list, to the free folios
+ *		   supplied as the target for the page migration
+ *
+ * @from:		The list of folios to be migrated.
+ * @get_new_folio:	The function used to allocate free folios to be used
+ *			as the target of the folio migration.
+ * @put_new_folio:	The function used to free target folios if migration
+ *			fails, or NULL if no special handling is necessary.
+ * @private:		Private data to be passed on to get_new_folio()
+ * @mode:		The migration mode that specifies the constraints for
+ *			folio migration, if any.
+ * @reason:		The reason for folio migration.
+ * @ret_succeeded:	Set to the number of folios migrated successfully if
+ *			the caller passes a non-NULL pointer.
+ *
+ * The function returns after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no folios
+ * are movable any more because the list has become empty or no retryable folios
+ * exist any more. It is caller's responsibility to call putback_movable_pages()
+ * only if ret != 0.
+ *
+ * Returns the number of {normal folio, large folio, hugetlb} that were not
+ * migrated, or an error code. The number of large folio splits will be
+ * considered as the number of non-migrated large folio, no matter how many
+ * split folios of the large folio are migrated successfully.
+ */
+int migrate_pages(struct list_head *from, new_folio_t get_new_folio,
+		free_folio_t put_new_folio, unsigned long private,
+		enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
+{
+	int rc, rc_gather;
+	int nr_pages;
+	struct folio *folio, *folio2;
+	LIST_HEAD(folios);
+	LIST_HEAD(ret_folios);
+	LIST_HEAD(split_folios);
+	struct migrate_pages_stats stats;
+
+	trace_mm_migrate_pages_start(mode, reason);
+
+	memset(&stats, 0, sizeof(stats));
+
+	rc_gather = migrate_hugetlbs(from, get_new_folio, put_new_folio, private,
+				     mode, reason, &stats, &ret_folios);
+	if (rc_gather < 0)
+		goto out;
+
+again:
+	nr_pages = 0;
+	list_for_each_entry_safe(folio, folio2, from, lru) {
+		/* Retried hugetlb folios will be kept in list  */
+		if (folio_test_hugetlb(folio)) {
+			list_move_tail(&folio->lru, &ret_folios);
+			continue;
+		}
+
+		nr_pages += folio_nr_pages(folio);
+		if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
+			break;
+	}
+	if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
+		list_cut_before(&folios, from, &folio2->lru);
+	else
+		list_splice_init(from, &folios);
+	if (mode == MIGRATE_ASYNC)
+		rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,
+				private, mode, reason, &ret_folios,
+				&split_folios, &stats,
+				NR_MAX_MIGRATE_PAGES_RETRY);
+	else
+		rc = migrate_pages_sync(&folios, get_new_folio, put_new_folio,
+				private, mode, reason, &ret_folios,
+				&split_folios, &stats);
+	list_splice_tail_init(&folios, &ret_folios);
+	if (rc < 0) {
+		rc_gather = rc;
+		list_splice_tail(&split_folios, &ret_folios);
+		goto out;
+	}
+	if (!list_empty(&split_folios)) {
+		/*
+		 * Failure isn't counted since all split folios of a large folio
+		 * is counted as 1 failure already.  And, we only try to migrate
+		 * with minimal effort, force MIGRATE_ASYNC mode and retry once.
+		 */
+		migrate_pages_batch(&split_folios, get_new_folio,
+				put_new_folio, private, MIGRATE_ASYNC, reason,
+				&ret_folios, NULL, &stats, 1);
+		list_splice_tail_init(&split_folios, &ret_folios);
+	}
+	rc_gather += rc;
+	if (!list_empty(from))
+		goto again;
+out:
+	/*
+	 * Put the permanent failure folio back to migration list, they
+	 * will be put back to the right list by the caller.
+	 */
+	list_splice(&ret_folios, from);
+
+	/*
+	 * Return 0 in case all split folios of fail-to-migrate large folios
+	 * are migrated successfully.
+	 */
+	if (list_empty(from))
+		rc_gather = 0;
+
+	count_vm_events(PGMIGRATE_SUCCESS, stats.nr_succeeded);
+	count_vm_events(PGMIGRATE_FAIL, stats.nr_failed_pages);
+	count_vm_events(THP_MIGRATION_SUCCESS, stats.nr_thp_succeeded);
+	count_vm_events(THP_MIGRATION_FAIL, stats.nr_thp_failed);
+	count_vm_events(THP_MIGRATION_SPLIT, stats.nr_thp_split);
+	trace_mm_migrate_pages(stats.nr_succeeded, stats.nr_failed_pages,
+			       stats.nr_thp_succeeded, stats.nr_thp_failed,
+			       stats.nr_thp_split, mode, reason);
+
+	if (ret_succeeded)
+		*ret_succeeded = stats.nr_succeeded;
+
+	return rc_gather;
+}
+
+struct folio *alloc_migration_target(struct folio *src, unsigned long private)
+{
+	struct migration_target_control *mtc;
+	gfp_t gfp_mask;
+	unsigned int order = 0;
+	int nid;
+	int zidx;
+
+	mtc = (struct migration_target_control *)private;
+	gfp_mask = mtc->gfp_mask;
+	nid = mtc->nid;
+	if (nid == NUMA_NO_NODE)
+		nid = folio_nid(src);
+
+	if (folio_test_hugetlb(src)) {
+		struct hstate *h = folio_hstate(src);
+
+		gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
+		return alloc_hugetlb_folio_nodemask(h, nid,
+						mtc->nmask, gfp_mask);
+	}
+
+	if (folio_test_large(src)) {
+		/*
+		 * clear __GFP_RECLAIM to make the migration callback
+		 * consistent with regular THP allocations.
+		 */
+		gfp_mask &= ~__GFP_RECLAIM;
+		gfp_mask |= GFP_TRANSHUGE;
+		order = folio_order(src);
+	}
+	zidx = zone_idx(folio_zone(src));
+	if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
+		gfp_mask |= __GFP_HIGHMEM;
+
+	return __folio_alloc(gfp_mask, order, nid, mtc->nmask);
+}
+
+#ifdef CONFIG_NUMA
+
+static int store_status(int __user *status, int start, int value, int nr)
+{
+	while (nr-- > 0) {
+		if (put_user(value, status + start))
+			return -EFAULT;
+		start++;
+	}
+
+	return 0;
+}
+
+static int do_move_pages_to_node(struct mm_struct *mm,
+		struct list_head *pagelist, int node)
+{
+	int err;
+	struct migration_target_control mtc = {
+		.nid = node,
+		.gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE,
+	};
+
+	err = migrate_pages(pagelist, alloc_migration_target, NULL,
+		(unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL);
+	if (err)
+		putback_movable_pages(pagelist);
+	return err;
+}
+
+/*
+ * Resolves the given address to a struct page, isolates it from the LRU and
+ * puts it to the given pagelist.
+ * Returns:
+ *     errno - if the page cannot be found/isolated
+ *     0 - when it doesn't have to be migrated because it is already on the
+ *         target node
+ *     1 - when it has been queued
+ */
+static int add_page_for_migration(struct mm_struct *mm, const void __user *p,
+		int node, struct list_head *pagelist, bool migrate_all)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr;
+	struct page *page;
+	int err;
+	bool isolated;
+
+	mmap_read_lock(mm);
+	addr = (unsigned long)untagged_addr_remote(mm, p);
+
+	err = -EFAULT;
+	vma = vma_lookup(mm, addr);
+	if (!vma || !vma_migratable(vma))
+		goto out;
+
+	/* FOLL_DUMP to ignore special (like zero) pages */
+	page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+
+	err = PTR_ERR(page);
+	if (IS_ERR(page))
+		goto out;
+
+	err = -ENOENT;
+	if (!page)
+		goto out;
+
+	if (is_zone_device_page(page))
+		goto out_putpage;
+
+	err = 0;
+	if (page_to_nid(page) == node)
+		goto out_putpage;
+
+	err = -EACCES;
+	if (page_mapcount(page) > 1 && !migrate_all)
+		goto out_putpage;
+
+	if (PageHuge(page)) {
+		if (PageHead(page)) {
+			isolated = isolate_hugetlb(page_folio(page), pagelist);
+			err = isolated ? 1 : -EBUSY;
+		}
+	} else {
+		struct page *head;
+
+		head = compound_head(page);
+		isolated = isolate_lru_page(head);
+		if (!isolated) {
+			err = -EBUSY;
+			goto out_putpage;
+		}
+
+		err = 1;
+		list_add_tail(&head->lru, pagelist);
+		mod_node_page_state(page_pgdat(head),
+			NR_ISOLATED_ANON + page_is_file_lru(head),
+			thp_nr_pages(head));
+	}
+out_putpage:
+	/*
+	 * Either remove the duplicate refcount from
+	 * isolate_lru_page() or drop the page ref if it was
+	 * not isolated.
+	 */
+	put_page(page);
+out:
+	mmap_read_unlock(mm);
+	return err;
+}
+
+static int move_pages_and_store_status(struct mm_struct *mm, int node,
+		struct list_head *pagelist, int __user *status,
+		int start, int i, unsigned long nr_pages)
+{
+	int err;
+
+	if (list_empty(pagelist))
+		return 0;
+
+	err = do_move_pages_to_node(mm, pagelist, node);
+	if (err) {
+		/*
+		 * Positive err means the number of failed
+		 * pages to migrate.  Since we are going to
+		 * abort and return the number of non-migrated
+		 * pages, so need to include the rest of the
+		 * nr_pages that have not been attempted as
+		 * well.
+		 */
+		if (err > 0)
+			err += nr_pages - i;
+		return err;
+	}
+	return store_status(status, start, node, i - start);
+}
+
+/*
+ * Migrate an array of page address onto an array of nodes and fill
+ * the corresponding array of status.
+ */
+static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
+			 unsigned long nr_pages,
+			 const void __user * __user *pages,
+			 const int __user *nodes,
+			 int __user *status, int flags)
+{
+	compat_uptr_t __user *compat_pages = (void __user *)pages;
+	int current_node = NUMA_NO_NODE;
+	LIST_HEAD(pagelist);
+	int start, i;
+	int err = 0, err1;
+
+	lru_cache_disable();
+
+	for (i = start = 0; i < nr_pages; i++) {
+		const void __user *p;
+		int node;
+
+		err = -EFAULT;
+		if (in_compat_syscall()) {
+			compat_uptr_t cp;
+
+			if (get_user(cp, compat_pages + i))
+				goto out_flush;
+
+			p = compat_ptr(cp);
+		} else {
+			if (get_user(p, pages + i))
+				goto out_flush;
+		}
+		if (get_user(node, nodes + i))
+			goto out_flush;
+
+		err = -ENODEV;
+		if (node < 0 || node >= MAX_NUMNODES)
+			goto out_flush;
+		if (!node_state(node, N_MEMORY))
+			goto out_flush;
+
+		err = -EACCES;
+		if (!node_isset(node, task_nodes))
+			goto out_flush;
+
+		if (current_node == NUMA_NO_NODE) {
+			current_node = node;
+			start = i;
+		} else if (node != current_node) {
+			err = move_pages_and_store_status(mm, current_node,
+					&pagelist, status, start, i, nr_pages);
+			if (err)
+				goto out;
+			start = i;
+			current_node = node;
+		}
+
+		/*
+		 * Errors in the page lookup or isolation are not fatal and we simply
+		 * report them via status
+		 */
+		err = add_page_for_migration(mm, p, current_node, &pagelist,
+					     flags & MPOL_MF_MOVE_ALL);
+
+		if (err > 0) {
+			/* The page is successfully queued for migration */
+			continue;
+		}
+
+		/*
+		 * The move_pages() man page does not have an -EEXIST choice, so
+		 * use -EFAULT instead.
+		 */
+		if (err == -EEXIST)
+			err = -EFAULT;
+
+		/*
+		 * If the page is already on the target node (!err), store the
+		 * node, otherwise, store the err.
+		 */
+		err = store_status(status, i, err ? : current_node, 1);
+		if (err)
+			goto out_flush;
+
+		err = move_pages_and_store_status(mm, current_node, &pagelist,
+				status, start, i, nr_pages);
+		if (err) {
+			/* We have accounted for page i */
+			if (err > 0)
+				err--;
+			goto out;
+		}
+		current_node = NUMA_NO_NODE;
+	}
+out_flush:
+	/* Make sure we do not overwrite the existing error */
+	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
+				status, start, i, nr_pages);
+	if (err >= 0)
+		err = err1;
+out:
+	lru_cache_enable();
+	return err;
+}
+
+/*
+ * Determine the nodes of an array of pages and store it in an array of status.
+ */
+static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
+				const void __user **pages, int *status)
+{
+	unsigned long i;
+
+	mmap_read_lock(mm);
+
+	for (i = 0; i < nr_pages; i++) {
+		unsigned long addr = (unsigned long)(*pages);
+		struct vm_area_struct *vma;
+		struct page *page;
+		int err = -EFAULT;
+
+		vma = vma_lookup(mm, addr);
+		if (!vma)
+			goto set_status;
+
+		/* FOLL_DUMP to ignore special (like zero) pages */
+		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto set_status;
+
+		err = -ENOENT;
+		if (!page)
+			goto set_status;
+
+		if (!is_zone_device_page(page))
+			err = page_to_nid(page);
+
+		put_page(page);
+set_status:
+		*status = err;
+
+		pages++;
+		status++;
+	}
+
+	mmap_read_unlock(mm);
+}
+
+static int get_compat_pages_array(const void __user *chunk_pages[],
+				  const void __user * __user *pages,
+				  unsigned long chunk_nr)
+{
+	compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
+	compat_uptr_t p;
+	int i;
+
+	for (i = 0; i < chunk_nr; i++) {
+		if (get_user(p, pages32 + i))
+			return -EFAULT;
+		chunk_pages[i] = compat_ptr(p);
+	}
+
+	return 0;
+}
+
+/*
+ * Determine the nodes of a user array of pages and store it in
+ * a user array of status.
+ */
+static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
+			 const void __user * __user *pages,
+			 int __user *status)
+{
+#define DO_PAGES_STAT_CHUNK_NR 16UL
+	const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
+	int chunk_status[DO_PAGES_STAT_CHUNK_NR];
+
+	while (nr_pages) {
+		unsigned long chunk_nr = min(nr_pages, DO_PAGES_STAT_CHUNK_NR);
+
+		if (in_compat_syscall()) {
+			if (get_compat_pages_array(chunk_pages, pages,
+						   chunk_nr))
+				break;
+		} else {
+			if (copy_from_user(chunk_pages, pages,
+				      chunk_nr * sizeof(*chunk_pages)))
+				break;
+		}
+
+		do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
+
+		if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
+			break;
+
+		pages += chunk_nr;
+		status += chunk_nr;
+		nr_pages -= chunk_nr;
+	}
+	return nr_pages ? -EFAULT : 0;
+}
+
+static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes)
+{
+	struct task_struct *task;
+	struct mm_struct *mm;
+
+	/*
+	 * There is no need to check if current process has the right to modify
+	 * the specified process when they are same.
+	 */
+	if (!pid) {
+		mmget(current->mm);
+		*mem_nodes = cpuset_mems_allowed(current);
+		return current->mm;
+	}
+
+	/* Find the mm_struct */
+	rcu_read_lock();
+	task = find_task_by_vpid(pid);
+	if (!task) {
+		rcu_read_unlock();
+		return ERR_PTR(-ESRCH);
+	}
+	get_task_struct(task);
+
+	/*
+	 * Check if this process has the right to modify the specified
+	 * process. Use the regular "ptrace_may_access()" checks.
+	 */
+	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
+		rcu_read_unlock();
+		mm = ERR_PTR(-EPERM);
+		goto out;
+	}
+	rcu_read_unlock();
+
+	mm = ERR_PTR(security_task_movememory(task));
+	if (IS_ERR(mm))
+		goto out;
+	*mem_nodes = cpuset_mems_allowed(task);
+	mm = get_task_mm(task);
+out:
+	put_task_struct(task);
+	if (!mm)
+		mm = ERR_PTR(-EINVAL);
+	return mm;
+}
+
+/*
+ * Move a list of pages in the address space of the currently executing
+ * process.
+ */
+static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
+			     const void __user * __user *pages,
+			     const int __user *nodes,
+			     int __user *status, int flags)
+{
+	struct mm_struct *mm;
+	int err;
+	nodemask_t task_nodes;
+
+	/* Check flags */
+	if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
+		return -EINVAL;
+
+	if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
+		return -EPERM;
+
+	mm = find_mm_struct(pid, &task_nodes);
+	if (IS_ERR(mm))
+		return PTR_ERR(mm);
+
+	if (nodes)
+		err = do_pages_move(mm, task_nodes, nr_pages, pages,
+				    nodes, status, flags);
+	else
+		err = do_pages_stat(mm, nr_pages, pages, status);
+
+	mmput(mm);
+	return err;
+}
+
+SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
+		const void __user * __user *, pages,
+		const int __user *, nodes,
+		int __user *, status, int, flags)
+{
+	return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+/*
+ * Returns true if this is a safe migration target node for misplaced NUMA
+ * pages. Currently it only checks the watermarks which is crude.
+ */
+static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
+				   unsigned long nr_migrate_pages)
+{
+	int z;
+
+	for (z = pgdat->nr_zones - 1; z >= 0; z--) {
+		struct zone *zone = pgdat->node_zones + z;
+
+		if (!managed_zone(zone))
+			continue;
+
+		/* Avoid waking kswapd by allocating pages_to_migrate pages. */
+		if (!zone_watermark_ok(zone, 0,
+				       high_wmark_pages(zone) +
+				       nr_migrate_pages,
+				       ZONE_MOVABLE, 0))
+			continue;
+		return true;
+	}
+	return false;
+}
+
+static struct folio *alloc_misplaced_dst_folio(struct folio *src,
+					   unsigned long data)
+{
+	int nid = (int) data;
+	int order = folio_order(src);
+	gfp_t gfp = __GFP_THISNODE;
+
+	if (order > 0)
+		gfp |= GFP_TRANSHUGE_LIGHT;
+	else {
+		gfp |= GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC | __GFP_NORETRY |
+			__GFP_NOWARN;
+		gfp &= ~__GFP_RECLAIM;
+	}
+	return __folio_alloc_node(gfp, order, nid);
+}
+
+static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
+{
+	int nr_pages = thp_nr_pages(page);
+	int order = compound_order(page);
+
+	VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
+
+	/* Do not migrate THP mapped by multiple processes */
+	if (PageTransHuge(page) && total_mapcount(page) > 1)
+		return 0;
+
+	/* Avoid migrating to a node that is nearly full */
+	if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
+		int z;
+
+		if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
+			return 0;
+		for (z = pgdat->nr_zones - 1; z >= 0; z--) {
+			if (managed_zone(pgdat->node_zones + z))
+				break;
+		}
+		wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
+		return 0;
+	}
+
+	if (!isolate_lru_page(page))
+		return 0;
+
+	mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_lru(page),
+			    nr_pages);
+
+	/*
+	 * Isolating the page has taken another reference, so the
+	 * caller's reference can be safely dropped without the page
+	 * disappearing underneath us during migration.
+	 */
+	put_page(page);
+	return 1;
+}
+
+/*
+ * Attempt to migrate a misplaced page to the specified destination
+ * node. Caller is expected to have an elevated reference count on
+ * the page that will be dropped by this function before returning.
+ */
+int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
+			   int node)
+{
+	pg_data_t *pgdat = NODE_DATA(node);
+	int isolated;
+	int nr_remaining;
+	unsigned int nr_succeeded;
+	LIST_HEAD(migratepages);
+	int nr_pages = thp_nr_pages(page);
+
+	/*
+	 * Don't migrate file pages that are mapped in multiple processes
+	 * with execute permissions as they are probably shared libraries.
+	 */
+	if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
+	    (vma->vm_flags & VM_EXEC))
+		goto out;
+
+	/*
+	 * Also do not migrate dirty pages as not all filesystems can move
+	 * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
+	 */
+	if (page_is_file_lru(page) && PageDirty(page))
+		goto out;
+
+	isolated = numamigrate_isolate_page(pgdat, page);
+	if (!isolated)
+		goto out;
+
+	list_add(&page->lru, &migratepages);
+	nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio,
+				     NULL, node, MIGRATE_ASYNC,
+				     MR_NUMA_MISPLACED, &nr_succeeded);
+	if (nr_remaining) {
+		if (!list_empty(&migratepages)) {
+			list_del(&page->lru);
+			mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
+					page_is_file_lru(page), -nr_pages);
+			putback_lru_page(page);
+		}
+		isolated = 0;
+	}
+	if (nr_succeeded) {
+		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
+		if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
+			mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
+					    nr_succeeded);
+	}
+	BUG_ON(!list_empty(&migratepages));
+	return isolated;
+
+out:
+	put_page(page);
+	return 0;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+#endif /* CONFIG_NUMA */