| // 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/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/gfp.h> |
| #include <linux/pfn_t.h> |
| #include <linux/page_idle.h> |
| #include <linux/page_owner.h> |
| #include <linux/sched/mm.h> |
| #include <linux/ptrace.h> |
| #include <linux/memory.h> |
| #include <linux/sched/sysctl.h> |
| #include <linux/memory-tiers.h> |
| #include <linux/pagewalk.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 the isolated flag */ |
| 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 |
| * __folio_test_movable 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); |
| } |
| } |
| } |
| |
| /* Must be called with an elevated refcount on the non-hugetlb folio */ |
| bool isolate_folio_to_list(struct folio *folio, struct list_head *list) |
| { |
| bool isolated, lru; |
| |
| if (folio_test_hugetlb(folio)) |
| return isolate_hugetlb(folio, list); |
| |
| lru = !__folio_test_movable(folio); |
| if (lru) |
| isolated = folio_isolate_lru(folio); |
| else |
| isolated = isolate_movable_page(&folio->page, |
| ISOLATE_UNEVICTABLE); |
| |
| if (!isolated) |
| return false; |
| |
| list_add(&folio->lru, list); |
| if (lru) |
| node_stat_add_folio(folio, NR_ISOLATED_ANON + |
| folio_is_file_lru(folio)); |
| |
| return true; |
| } |
| |
| static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, |
| struct folio *folio, |
| unsigned long idx) |
| { |
| struct page *page = folio_page(folio, idx); |
| bool contains_data; |
| pte_t newpte; |
| void *addr; |
| |
| if (PageCompound(page)) |
| return false; |
| VM_BUG_ON_PAGE(!PageAnon(page), page); |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); |
| |
| if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) || |
| mm_forbids_zeropage(pvmw->vma->vm_mm)) |
| return false; |
| |
| /* |
| * The pmd entry mapping the old thp was flushed and the pte mapping |
| * this subpage has been non present. If the subpage is only zero-filled |
| * then map it to the shared zeropage. |
| */ |
| addr = kmap_local_page(page); |
| contains_data = memchr_inv(addr, 0, PAGE_SIZE); |
| kunmap_local(addr); |
| |
| if (contains_data) |
| return false; |
| |
| newpte = pte_mkspecial(pfn_pte(my_zero_pfn(pvmw->address), |
| pvmw->vma->vm_page_prot)); |
| set_pte_at(pvmw->vma->vm_mm, pvmw->address, pvmw->pte, newpte); |
| |
| dec_mm_counter(pvmw->vma->vm_mm, mm_counter(folio)); |
| return true; |
| } |
| |
| struct rmap_walk_arg { |
| struct folio *folio; |
| bool map_unused_to_zeropage; |
| }; |
| |
| /* |
| * 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 *arg) |
| { |
| struct rmap_walk_arg *rmap_walk_arg = arg; |
| DEFINE_FOLIO_VMA_WALK(pvmw, rmap_walk_arg->folio, 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 |
| if (rmap_walk_arg->map_unused_to_zeropage && |
| try_to_map_unused_to_zeropage(&pvmw, folio, idx)) |
| continue; |
| |
| folio_get(folio); |
| pte = mk_pte(new, READ_ONCE(vma->vm_page_prot)); |
| old_pte = ptep_get(pvmw.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 (pte_swp_soft_dirty(old_pte)) |
| pte = pte_mksoft_dirty(pte); |
| else |
| pte = pte_clear_soft_dirty(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)) |
| hugetlb_add_anon_rmap(folio, vma, pvmw.address, |
| rmap_flags); |
| else |
| hugetlb_add_file_rmap(folio); |
| set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte, |
| psize); |
| } else |
| #endif |
| { |
| if (folio_test_anon(folio)) |
| folio_add_anon_rmap_pte(folio, new, vma, |
| pvmw.address, rmap_flags); |
| else |
| folio_add_file_rmap_pte(folio, new, vma); |
| 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, int flags) |
| { |
| struct rmap_walk_arg rmap_walk_arg = { |
| .folio = src, |
| .map_unused_to_zeropage = flags & RMP_USE_SHARED_ZEROPAGE, |
| }; |
| |
| struct rmap_walk_control rwc = { |
| .rmap_one = remove_migration_pte, |
| .arg = &rmap_walk_arg, |
| }; |
| |
| VM_BUG_ON_FOLIO((flags & RMP_USE_SHARED_ZEROPAGE) && (src != dst), src); |
| |
| if (flags & RMP_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, unsigned long addr, 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(vma->vm_mm, addr, 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 folio in the mapping. |
| * |
| * The number of remaining references must be: |
| * 1 for anonymous folios without a mapping |
| * 2 for folios with a mapping |
| * 3 for folios with a mapping and the private flag set. |
| */ |
| static int __folio_migrate_mapping(struct address_space *mapping, |
| struct folio *newfolio, struct folio *folio, int expected_count) |
| { |
| XA_STATE(xas, &mapping->i_pages, folio_index(folio)); |
| struct zone *oldzone, *newzone; |
| int dirty; |
| long nr = folio_nr_pages(folio); |
| long entries, i; |
| |
| if (!mapping) { |
| /* Take off deferred split queue while frozen and memcg set */ |
| if (folio_test_large(folio) && |
| folio_test_large_rmappable(folio)) { |
| if (!folio_ref_freeze(folio, expected_count)) |
| return -EAGAIN; |
| folio_unqueue_deferred_split(folio); |
| folio_ref_unfreeze(folio, expected_count); |
| } |
| |
| /* No turning back from here */ |
| newfolio->index = folio->index; |
| newfolio->mapping = folio->mapping; |
| if (folio_test_anon(folio) && folio_test_large(folio)) |
| mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1); |
| 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; |
| } |
| |
| /* Take off deferred split queue while frozen and memcg set */ |
| folio_unqueue_deferred_split(folio); |
| |
| /* |
| * 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; |
| if (folio_test_anon(folio) && folio_test_large(folio)) |
| mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1); |
| 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 folio refs frozen and newfolio 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 folio 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 folio for that zone. Other VM counters will be |
| * taken care of when we establish references to the |
| * new folio and drop references to the old folio. |
| * |
| * Note that anonymous folios 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; |
| } |
| |
| int folio_migrate_mapping(struct address_space *mapping, |
| struct folio *newfolio, struct folio *folio, int extra_count) |
| { |
| int expected_count = folio_expected_refs(mapping, folio) + extra_count; |
| |
| if (folio_ref_count(folio) != expected_count) |
| return -EAGAIN; |
| |
| return __folio_migrate_mapping(mapping, newfolio, folio, expected_count); |
| } |
| 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 rc, expected_count = folio_expected_refs(mapping, src); |
| |
| if (folio_ref_count(src) != expected_count) |
| return -EAGAIN; |
| |
| rc = folio_mc_copy(dst, src); |
| if (unlikely(rc)) |
| return rc; |
| |
| xas_lock_irq(&xas); |
| if (!folio_ref_freeze(src, expected_count)) { |
| xas_unlock_irq(&xas); |
| return -EAGAIN; |
| } |
| |
| dst->index = src->index; |
| dst->mapping = src->mapping; |
| |
| folio_ref_add(dst, folio_nr_pages(dst)); |
| |
| xas_store(&xas, dst); |
| |
| folio_ref_unfreeze(src, expected_count - folio_nr_pages(src)); |
| |
| 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_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); |
| |
| folio_migrate_refs(newfolio, folio); |
| /* |
| * Copy NUMA information to the new page, to prevent over-eager |
| * future migrations of this same page. |
| */ |
| cpupid = folio_xchg_last_cpupid(folio, -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(folio_nid(folio)); |
| bool t_toptier = node_is_toptier(folio_nid(newfolio)); |
| |
| if (f_toptier != t_toptier) |
| cpupid = -1; |
| } |
| folio_xchg_last_cpupid(newfolio, cpupid); |
| |
| folio_migrate_ksm(newfolio, folio); |
| /* |
| * Please do not reorder this without considering how mm/ksm.c's |
| * ksm_get_folio() depends upon ksm_migrate_page() and the |
| * swapcache flag. |
| */ |
| 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); |
| pgalloc_tag_copy(newfolio, folio); |
| |
| mem_cgroup_migrate(folio, newfolio); |
| } |
| EXPORT_SYMBOL(folio_migrate_flags); |
| |
| /************************************************************ |
| * Migration functions |
| ***********************************************************/ |
| |
| static int __migrate_folio(struct address_space *mapping, struct folio *dst, |
| struct folio *src, void *src_private, |
| enum migrate_mode mode) |
| { |
| int rc, expected_count = folio_expected_refs(mapping, src); |
| |
| /* Check whether src does not have extra refs before we do more work */ |
| if (folio_ref_count(src) != expected_count) |
| return -EAGAIN; |
| |
| rc = folio_mc_copy(dst, src); |
| if (unlikely(rc)) |
| return rc; |
| |
| rc = __folio_migrate_mapping(mapping, dst, src, expected_count); |
| if (rc != MIGRATEPAGE_SUCCESS) |
| return rc; |
| |
| if (src_private) |
| folio_attach_private(dst, folio_detach_private(src)); |
| |
| 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 have private data. |
| * |
| * Folios are locked upon entry and exit. |
| */ |
| int migrate_folio(struct address_space *mapping, struct folio *dst, |
| struct folio *src, enum migrate_mode mode) |
| { |
| BUG_ON(folio_test_writeback(src)); /* Writeback must be complete */ |
| return __migrate_folio(mapping, dst, src, NULL, mode); |
| } |
| 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->i_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->i_private_lock); |
| invalidate_bh_lrus(); |
| invalidated = true; |
| goto recheck_buffers; |
| } |
| } |
| |
| rc = filemap_migrate_folio(mapping, dst, src, mode); |
| if (rc != MIGRATEPAGE_SUCCESS) |
| goto unlock_buffers; |
| |
| bh = head; |
| do { |
| folio_set_bh(bh, dst, bh_offset(bh)); |
| bh = bh->b_this_page; |
| } while (bh != head); |
| |
| unlock_buffers: |
| if (check_refs) |
| spin_unlock(&mapping->i_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) |
| { |
| return __migrate_folio(mapping, dst, src, folio_get_private(src), mode); |
| } |
| 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, 0); |
| |
| 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: |
| 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 = !__folio_test_movable(src); |
| |
| 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_inaccessible(mapping)) |
| rc = -EOPNOTSUPP; |
| 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 (__folio_test_movable(src)) { |
| 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, 0); |
| /* 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 __folio_test_movable |
| */ |
| if (likely(!__folio_test_movable(src)) && reason != MR_DEMOTION) |
| 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 = data_race(!__folio_test_movable(src)); |
| 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: |
| 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 = !__folio_test_movable(src); |
| 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, 0); |
| |
| 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: |
| 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_folio_mapping_lock_write(src); |
| 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, 0); |
| |
| 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, |
| enum migrate_mode mode) |
| { |
| int rc; |
| |
| if (mode == MIGRATE_ASYNC) { |
| if (!folio_trylock(folio)) |
| return -EAGAIN; |
| } else { |
| 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 */ |
| int nr_split; /* Large folio (include 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; |
| bool is_large = 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_large = folio_test_large(folio); |
| is_thp = folio_test_pmd_mappable(folio); |
| nr_pages = folio_nr_pages(folio); |
| |
| cond_resched(); |
| |
| /* |
| * The rare folio on the deferred split list should |
| * be split now. It should not count as a failure: |
| * but increment nr_failed because, without doing so, |
| * migrate_pages() may report success with (split but |
| * unmigrated) pages still on its fromlist; whereas it |
| * always reports success when its fromlist is empty. |
| * stats->nr_thp_failed should be increased too, |
| * otherwise stats inconsistency will happen when |
| * migrate_pages_batch is called via migrate_pages() |
| * with MIGRATE_SYNC and MIGRATE_ASYNC. |
| * |
| * Only check it without removing it from the list. |
| * Since the folio can be on deferred_split_scan() |
| * local list and removing it can cause the local list |
| * corruption. Folio split process below can handle it |
| * with the help of folio_ref_freeze(). |
| * |
| * nr_pages > 2 is needed to avoid checking order-1 |
| * page cache folios. They exist, in contrast to |
| * non-existent order-1 anonymous folios, and do not |
| * use _deferred_list. |
| */ |
| if (nr_pages > 2 && |
| !list_empty(&folio->_deferred_list) && |
| folio_test_partially_mapped(folio)) { |
| if (!try_split_folio(folio, split_folios, mode)) { |
| nr_failed++; |
| stats->nr_thp_failed += is_thp; |
| stats->nr_thp_split += is_thp; |
| stats->nr_split++; |
| continue; |
| } |
| } |
| |
| /* |
| * 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, mode)) { |
| stats->nr_thp_split++; |
| stats->nr_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 (is_large && !nosplit) { |
| int ret = try_split_folio(folio, split_folios, mode); |
| |
| if (!ret) { |
| stats->nr_thp_split += is_thp; |
| stats->nr_split++; |
| 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; |
| stats->nr_split += astats.nr_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; |
| /* |
| * Do not count rc, as pages will be retried below. |
| * Count nr_split only, since it includes nr_thp_split. |
| */ |
| nr_failed += astats.nr_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, stats.nr_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, |
| htlb_allow_alloc_fallback(mtc->reason)); |
| } |
| |
| 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 list_head *pagelist, int node) |
| { |
| int err; |
| struct migration_target_control mtc = { |
| .nid = node, |
| .gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, |
| .reason = MR_SYSCALL, |
| }; |
| |
| err = migrate_pages(pagelist, alloc_migration_target, NULL, |
| (unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL); |
| if (err) |
| putback_movable_pages(pagelist); |
| return err; |
| } |
| |
| static int __add_folio_for_migration(struct folio *folio, int node, |
| struct list_head *pagelist, bool migrate_all) |
| { |
| if (is_zero_folio(folio) || is_huge_zero_folio(folio)) |
| return -EFAULT; |
| |
| if (folio_is_zone_device(folio)) |
| return -ENOENT; |
| |
| if (folio_nid(folio) == node) |
| return 0; |
| |
| if (folio_likely_mapped_shared(folio) && !migrate_all) |
| return -EACCES; |
| |
| if (folio_test_hugetlb(folio)) { |
| if (isolate_hugetlb(folio, pagelist)) |
| return 1; |
| } else if (folio_isolate_lru(folio)) { |
| list_add_tail(&folio->lru, pagelist); |
| node_stat_mod_folio(folio, |
| NR_ISOLATED_ANON + folio_is_file_lru(folio), |
| folio_nr_pages(folio)); |
| return 1; |
| } |
| return -EBUSY; |
| } |
| |
| /* |
| * Resolves the given address to a struct folio, isolates it from the LRU and |
| * puts it to the given pagelist. |
| * Returns: |
| * errno - if the folio 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_folio_for_migration(struct mm_struct *mm, const void __user *p, |
| int node, struct list_head *pagelist, bool migrate_all) |
| { |
| struct vm_area_struct *vma; |
| struct folio_walk fw; |
| struct folio *folio; |
| unsigned long addr; |
| int err = -EFAULT; |
| |
| mmap_read_lock(mm); |
| addr = (unsigned long)untagged_addr_remote(mm, p); |
| |
| vma = vma_lookup(mm, addr); |
| if (vma && vma_migratable(vma)) { |
| folio = folio_walk_start(&fw, vma, addr, FW_ZEROPAGE); |
| if (folio) { |
| err = __add_folio_for_migration(folio, node, pagelist, |
| migrate_all); |
| folio_walk_end(&fw, vma); |
| } else { |
| err = -ENOENT; |
| } |
| } |
| mmap_read_unlock(mm); |
| return err; |
| } |
| |
| static int move_pages_and_store_status(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(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(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_folio_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(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(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 folio_walk fw; |
| struct folio *folio; |
| int err = -EFAULT; |
| |
| vma = vma_lookup(mm, addr); |
| if (!vma) |
| goto set_status; |
| |
| folio = folio_walk_start(&fw, vma, addr, FW_ZEROPAGE); |
| if (folio) { |
| if (is_zero_folio(folio) || is_huge_zero_folio(folio)) |
| err = -EFAULT; |
| else if (folio_is_zone_device(folio)) |
| err = -ENOENT; |
| else |
| err = folio_nid(folio); |
| folio_walk_end(&fw, vma); |
| } else { |
| err = -ENOENT; |
| } |
| 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; |
| } |
| |
| task = find_get_task_by_vpid(pid); |
| if (!task) { |
| return ERR_PTR(-ESRCH); |
| } |
| |
| /* |
| * 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)) { |
| mm = ERR_PTR(-EPERM); |
| goto out; |
| } |
| |
| 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, ALLOC_CMA)) |
| 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); |
| } |
| |
| /* |
| * Prepare for calling migrate_misplaced_folio() by isolating the folio if |
| * permitted. Must be called with the PTL still held. |
| */ |
| int migrate_misplaced_folio_prepare(struct folio *folio, |
| struct vm_area_struct *vma, int node) |
| { |
| int nr_pages = folio_nr_pages(folio); |
| pg_data_t *pgdat = NODE_DATA(node); |
| |
| if (folio_is_file_lru(folio)) { |
| /* |
| * Do not migrate file folios that are mapped in multiple |
| * processes with execute permissions as they are probably |
| * shared libraries. |
| * |
| * See folio_likely_mapped_shared() on possible imprecision |
| * when we cannot easily detect if a folio is shared. |
| */ |
| if ((vma->vm_flags & VM_EXEC) && |
| folio_likely_mapped_shared(folio)) |
| return -EACCES; |
| |
| /* |
| * Do not migrate dirty folios as not all filesystems can move |
| * dirty folios in MIGRATE_ASYNC mode which is a waste of |
| * cycles. |
| */ |
| if (folio_test_dirty(folio)) |
| return -EAGAIN; |
| } |
| |
| /* 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 -EAGAIN; |
| for (z = pgdat->nr_zones - 1; z >= 0; z--) { |
| if (managed_zone(pgdat->node_zones + z)) |
| break; |
| } |
| |
| /* |
| * If there are no managed zones, it should not proceed |
| * further. |
| */ |
| if (z < 0) |
| return -EAGAIN; |
| |
| wakeup_kswapd(pgdat->node_zones + z, 0, |
| folio_order(folio), ZONE_MOVABLE); |
| return -EAGAIN; |
| } |
| |
| if (!folio_isolate_lru(folio)) |
| return -EAGAIN; |
| |
| node_stat_mod_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio), |
| nr_pages); |
| return 0; |
| } |
| |
| /* |
| * Attempt to migrate a misplaced folio to the specified destination |
| * node. Caller is expected to have isolated the folio by calling |
| * migrate_misplaced_folio_prepare(), which will result in an |
| * elevated reference count on the folio. This function will un-isolate the |
| * folio, dereferencing the folio before returning. |
| */ |
| int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma, |
| int node) |
| { |
| pg_data_t *pgdat = NODE_DATA(node); |
| int nr_remaining; |
| unsigned int nr_succeeded; |
| LIST_HEAD(migratepages); |
| struct mem_cgroup *memcg = get_mem_cgroup_from_folio(folio); |
| struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); |
| |
| list_add(&folio->lru, &migratepages); |
| nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio, |
| NULL, node, MIGRATE_ASYNC, |
| MR_NUMA_MISPLACED, &nr_succeeded); |
| if (nr_remaining && !list_empty(&migratepages)) |
| putback_movable_pages(&migratepages); |
| if (nr_succeeded) { |
| count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded); |
| count_memcg_events(memcg, NUMA_PAGE_MIGRATE, nr_succeeded); |
| if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) |
| && !node_is_toptier(folio_nid(folio)) |
| && node_is_toptier(node)) |
| mod_lruvec_state(lruvec, PGPROMOTE_SUCCESS, nr_succeeded); |
| } |
| mem_cgroup_put(memcg); |
| BUG_ON(!list_empty(&migratepages)); |
| return nr_remaining ? -EAGAIN : 0; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| #endif /* CONFIG_NUMA */ |