| // 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/pagevec.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/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/mmu_notifier.h> |
| #include <linux/page_idle.h> |
| #include <linux/page_owner.h> |
| #include <linux/sched/mm.h> |
| #include <linux/ptrace.h> |
| |
| #include <asm/tlbflush.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/migrate.h> |
| |
| #include "internal.h" |
| |
| /* |
| * migrate_prep() needs to be called before we start compiling a list of pages |
| * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is |
| * undesirable, use migrate_prep_local() |
| */ |
| int migrate_prep(void) |
| { |
| /* |
| * Clear the LRU lists so pages can be isolated. |
| * Note that pages may be moved off the LRU after we have |
| * drained them. Those pages will fail to migrate like other |
| * pages that may be busy. |
| */ |
| lru_add_drain_all(); |
| |
| return 0; |
| } |
| |
| /* Do the necessary work of migrate_prep but not if it involves other CPUs */ |
| int migrate_prep_local(void) |
| { |
| lru_add_drain(); |
| |
| return 0; |
| } |
| |
| int isolate_movable_page(struct page *page, isolate_mode_t mode) |
| { |
| struct address_space *mapping; |
| |
| /* |
| * 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 (unlikely(!get_page_unless_zero(page))) |
| goto out; |
| |
| /* |
| * Check PageMovable before holding a PG_lock because page's owner |
| * assumes anybody doesn't touch PG_lock of newly allocated page |
| * so unconditionally grapping the lock ruins page's owner side. |
| */ |
| if (unlikely(!__PageMovable(page))) |
| goto out_putpage; |
| /* |
| * 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(!trylock_page(page))) |
| goto out_putpage; |
| |
| if (!PageMovable(page) || PageIsolated(page)) |
| goto out_no_isolated; |
| |
| mapping = page_mapping(page); |
| VM_BUG_ON_PAGE(!mapping, page); |
| |
| if (!mapping->a_ops->isolate_page(page, mode)) |
| goto out_no_isolated; |
| |
| /* Driver shouldn't use PG_isolated bit of page->flags */ |
| WARN_ON_ONCE(PageIsolated(page)); |
| __SetPageIsolated(page); |
| unlock_page(page); |
| |
| return 0; |
| |
| out_no_isolated: |
| unlock_page(page); |
| out_putpage: |
| put_page(page); |
| out: |
| return -EBUSY; |
| } |
| |
| /* It should be called on page which is PG_movable */ |
| void putback_movable_page(struct page *page) |
| { |
| struct address_space *mapping; |
| |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| VM_BUG_ON_PAGE(!PageMovable(page), page); |
| VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| |
| mapping = page_mapping(page); |
| mapping->a_ops->putback_page(page); |
| __ClearPageIsolated(page); |
| } |
| |
| /* |
| * 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_huge_page(). |
| */ |
| void putback_movable_pages(struct list_head *l) |
| { |
| struct page *page; |
| struct page *page2; |
| |
| list_for_each_entry_safe(page, page2, l, lru) { |
| if (unlikely(PageHuge(page))) { |
| putback_active_hugepage(page); |
| continue; |
| } |
| list_del(&page->lru); |
| /* |
| * We isolated non-lru movable page so here we can use |
| * __PageMovable because LRU page's mapping cannot have |
| * PAGE_MAPPING_MOVABLE. |
| */ |
| if (unlikely(__PageMovable(page))) { |
| VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| lock_page(page); |
| if (PageMovable(page)) |
| putback_movable_page(page); |
| else |
| __ClearPageIsolated(page); |
| unlock_page(page); |
| put_page(page); |
| } else { |
| mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + |
| page_is_file_cache(page), -hpage_nr_pages(page)); |
| putback_lru_page(page); |
| } |
| } |
| } |
| |
| /* |
| * Restore a potential migration pte to a working pte entry |
| */ |
| static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, |
| unsigned long addr, void *old) |
| { |
| struct page_vma_mapped_walk pvmw = { |
| .page = old, |
| .vma = vma, |
| .address = addr, |
| .flags = PVMW_SYNC | PVMW_MIGRATION, |
| }; |
| struct page *new; |
| pte_t pte; |
| swp_entry_t entry; |
| |
| VM_BUG_ON_PAGE(PageTail(page), page); |
| while (page_vma_mapped_walk(&pvmw)) { |
| if (PageKsm(page)) |
| new = page; |
| else |
| new = page - pvmw.page->index + |
| linear_page_index(vma, pvmw.address); |
| |
| #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
| /* PMD-mapped THP migration entry */ |
| if (!pvmw.pte) { |
| VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page); |
| remove_migration_pmd(&pvmw, new); |
| continue; |
| } |
| #endif |
| |
| get_page(new); |
| pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot))); |
| if (pte_swp_soft_dirty(*pvmw.pte)) |
| pte = pte_mksoft_dirty(pte); |
| |
| /* |
| * Recheck VMA as permissions can change since migration started |
| */ |
| entry = pte_to_swp_entry(*pvmw.pte); |
| if (is_write_migration_entry(entry)) |
| pte = maybe_mkwrite(pte, vma); |
| |
| if (unlikely(is_zone_device_page(new))) { |
| if (is_device_private_page(new)) { |
| entry = make_device_private_entry(new, pte_write(pte)); |
| pte = swp_entry_to_pte(entry); |
| } else if (is_device_public_page(new)) { |
| pte = pte_mkdevmap(pte); |
| flush_dcache_page(new); |
| } |
| } else |
| flush_dcache_page(new); |
| |
| #ifdef CONFIG_HUGETLB_PAGE |
| if (PageHuge(new)) { |
| pte = pte_mkhuge(pte); |
| pte = arch_make_huge_pte(pte, vma, new, 0); |
| set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); |
| if (PageAnon(new)) |
| hugepage_add_anon_rmap(new, vma, pvmw.address); |
| else |
| page_dup_rmap(new, true); |
| } else |
| #endif |
| { |
| set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); |
| |
| if (PageAnon(new)) |
| page_add_anon_rmap(new, vma, pvmw.address, false); |
| else |
| page_add_file_rmap(new, false); |
| } |
| if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new)) |
| mlock_vma_page(new); |
| |
| if (PageTransHuge(page) && PageMlocked(page)) |
| clear_page_mlock(page); |
| |
| /* 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 page *old, struct page *new, bool locked) |
| { |
| struct rmap_walk_control rwc = { |
| .rmap_one = remove_migration_pte, |
| .arg = old, |
| }; |
| |
| if (locked) |
| rmap_walk_locked(new, &rwc); |
| else |
| rmap_walk(new, &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, pte_t *ptep, |
| spinlock_t *ptl) |
| { |
| pte_t pte; |
| swp_entry_t entry; |
| struct page *page; |
| |
| spin_lock(ptl); |
| pte = *ptep; |
| if (!is_swap_pte(pte)) |
| goto out; |
| |
| entry = pte_to_swp_entry(pte); |
| if (!is_migration_entry(entry)) |
| goto out; |
| |
| page = migration_entry_to_page(entry); |
| |
| /* |
| * Once radix-tree replacement of page migration started, page_count |
| * *must* be zero. And, we don't want to call wait_on_page_locked() |
| * against a page without get_page(). |
| * So, we use get_page_unless_zero(), here. Even failed, page fault |
| * will occur again. |
| */ |
| if (!get_page_unless_zero(page)) |
| goto out; |
| pte_unmap_unlock(ptep, ptl); |
| wait_on_page_locked(page); |
| put_page(page); |
| return; |
| out: |
| pte_unmap_unlock(ptep, ptl); |
| } |
| |
| void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long address) |
| { |
| spinlock_t *ptl = pte_lockptr(mm, pmd); |
| pte_t *ptep = pte_offset_map(pmd, address); |
| __migration_entry_wait(mm, ptep, ptl); |
| } |
| |
| void migration_entry_wait_huge(struct vm_area_struct *vma, |
| struct mm_struct *mm, pte_t *pte) |
| { |
| spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); |
| __migration_entry_wait(mm, pte, ptl); |
| } |
| |
| #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
| void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd) |
| { |
| spinlock_t *ptl; |
| struct page *page; |
| |
| ptl = pmd_lock(mm, pmd); |
| if (!is_pmd_migration_entry(*pmd)) |
| goto unlock; |
| page = migration_entry_to_page(pmd_to_swp_entry(*pmd)); |
| if (!get_page_unless_zero(page)) |
| goto unlock; |
| spin_unlock(ptl); |
| wait_on_page_locked(page); |
| put_page(page); |
| return; |
| unlock: |
| spin_unlock(ptl); |
| } |
| #endif |
| |
| #ifdef CONFIG_BLOCK |
| /* 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; |
| |
| /* Simple case, sync compaction */ |
| if (mode != MIGRATE_ASYNC) { |
| do { |
| get_bh(bh); |
| lock_buffer(bh); |
| bh = bh->b_this_page; |
| |
| } while (bh != head); |
| |
| return true; |
| } |
| |
| /* async case, we cannot block on lock_buffer so use trylock_buffer */ |
| do { |
| get_bh(bh); |
| if (!trylock_buffer(bh)) { |
| /* |
| * We failed to lock the buffer and cannot stall in |
| * async migration. Release the taken locks |
| */ |
| struct buffer_head *failed_bh = bh; |
| put_bh(failed_bh); |
| bh = head; |
| while (bh != failed_bh) { |
| unlock_buffer(bh); |
| put_bh(bh); |
| bh = bh->b_this_page; |
| } |
| return false; |
| } |
| |
| bh = bh->b_this_page; |
| } while (bh != head); |
| return true; |
| } |
| #else |
| static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, |
| enum migrate_mode mode) |
| { |
| return true; |
| } |
| #endif /* CONFIG_BLOCK */ |
| |
| /* |
| * 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 migrate_page_move_mapping(struct address_space *mapping, |
| struct page *newpage, struct page *page, |
| struct buffer_head *head, enum migrate_mode mode, |
| int extra_count) |
| { |
| struct zone *oldzone, *newzone; |
| int dirty; |
| int expected_count = 1 + extra_count; |
| void **pslot; |
| |
| /* |
| * Device public or private pages have an extra refcount as they are |
| * ZONE_DEVICE pages. |
| */ |
| expected_count += is_device_private_page(page); |
| expected_count += is_device_public_page(page); |
| |
| if (!mapping) { |
| /* Anonymous page without mapping */ |
| if (page_count(page) != expected_count) |
| return -EAGAIN; |
| |
| /* No turning back from here */ |
| newpage->index = page->index; |
| newpage->mapping = page->mapping; |
| if (PageSwapBacked(page)) |
| __SetPageSwapBacked(newpage); |
| |
| return MIGRATEPAGE_SUCCESS; |
| } |
| |
| oldzone = page_zone(page); |
| newzone = page_zone(newpage); |
| |
| spin_lock_irq(&mapping->tree_lock); |
| |
| pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| page_index(page)); |
| |
| expected_count += 1 + page_has_private(page); |
| if (page_count(page) != expected_count || |
| radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return -EAGAIN; |
| } |
| |
| if (!page_ref_freeze(page, expected_count)) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return -EAGAIN; |
| } |
| |
| /* |
| * In the async migration case of moving a page with buffers, lock the |
| * buffers using trylock before the mapping is moved. If the mapping |
| * was moved, we later failed to lock the buffers and could not move |
| * the mapping back due to an elevated page count, we would have to |
| * block waiting on other references to be dropped. |
| */ |
| if (mode == MIGRATE_ASYNC && head && |
| !buffer_migrate_lock_buffers(head, mode)) { |
| page_ref_unfreeze(page, expected_count); |
| spin_unlock_irq(&mapping->tree_lock); |
| return -EAGAIN; |
| } |
| |
| /* |
| * Now we know that no one else is looking at the page: |
| * no turning back from here. |
| */ |
| newpage->index = page->index; |
| newpage->mapping = page->mapping; |
| get_page(newpage); /* add cache reference */ |
| if (PageSwapBacked(page)) { |
| __SetPageSwapBacked(newpage); |
| if (PageSwapCache(page)) { |
| SetPageSwapCache(newpage); |
| set_page_private(newpage, page_private(page)); |
| } |
| } else { |
| VM_BUG_ON_PAGE(PageSwapCache(page), page); |
| } |
| |
| /* Move dirty while page refs frozen and newpage not yet exposed */ |
| dirty = PageDirty(page); |
| if (dirty) { |
| ClearPageDirty(page); |
| SetPageDirty(newpage); |
| } |
| |
| radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); |
| |
| /* |
| * Drop cache reference from old page by unfreezing |
| * to one less reference. |
| * We know this isn't the last reference. |
| */ |
| page_ref_unfreeze(page, expected_count - 1); |
| |
| spin_unlock(&mapping->tree_lock); |
| /* 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) { |
| __dec_node_state(oldzone->zone_pgdat, NR_FILE_PAGES); |
| __inc_node_state(newzone->zone_pgdat, NR_FILE_PAGES); |
| if (PageSwapBacked(page) && !PageSwapCache(page)) { |
| __dec_node_state(oldzone->zone_pgdat, NR_SHMEM); |
| __inc_node_state(newzone->zone_pgdat, NR_SHMEM); |
| } |
| if (dirty && mapping_cap_account_dirty(mapping)) { |
| __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY); |
| __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); |
| __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY); |
| __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); |
| } |
| } |
| local_irq_enable(); |
| |
| return MIGRATEPAGE_SUCCESS; |
| } |
| EXPORT_SYMBOL(migrate_page_move_mapping); |
| |
| /* |
| * The expected number of remaining references is the same as that |
| * of migrate_page_move_mapping(). |
| */ |
| int migrate_huge_page_move_mapping(struct address_space *mapping, |
| struct page *newpage, struct page *page) |
| { |
| int expected_count; |
| void **pslot; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| |
| pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| page_index(page)); |
| |
| expected_count = 2 + page_has_private(page); |
| if (page_count(page) != expected_count || |
| radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return -EAGAIN; |
| } |
| |
| if (!page_ref_freeze(page, expected_count)) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return -EAGAIN; |
| } |
| |
| newpage->index = page->index; |
| newpage->mapping = page->mapping; |
| |
| get_page(newpage); |
| |
| radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); |
| |
| page_ref_unfreeze(page, expected_count - 1); |
| |
| spin_unlock_irq(&mapping->tree_lock); |
| |
| return MIGRATEPAGE_SUCCESS; |
| } |
| |
| /* |
| * Gigantic pages are so large that we do not guarantee that page++ pointer |
| * arithmetic will work across the entire page. We need something more |
| * specialized. |
| */ |
| static void __copy_gigantic_page(struct page *dst, struct page *src, |
| int nr_pages) |
| { |
| int i; |
| struct page *dst_base = dst; |
| struct page *src_base = src; |
| |
| for (i = 0; i < nr_pages; ) { |
| cond_resched(); |
| copy_highpage(dst, src); |
| |
| i++; |
| dst = mem_map_next(dst, dst_base, i); |
| src = mem_map_next(src, src_base, i); |
| } |
| } |
| |
| static void copy_huge_page(struct page *dst, struct page *src) |
| { |
| int i; |
| int nr_pages; |
| |
| if (PageHuge(src)) { |
| /* hugetlbfs page */ |
| struct hstate *h = page_hstate(src); |
| nr_pages = pages_per_huge_page(h); |
| |
| if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { |
| __copy_gigantic_page(dst, src, nr_pages); |
| return; |
| } |
| } else { |
| /* thp page */ |
| BUG_ON(!PageTransHuge(src)); |
| nr_pages = hpage_nr_pages(src); |
| } |
| |
| for (i = 0; i < nr_pages; i++) { |
| cond_resched(); |
| copy_highpage(dst + i, src + i); |
| } |
| } |
| |
| /* |
| * Copy the page to its new location |
| */ |
| void migrate_page_states(struct page *newpage, struct page *page) |
| { |
| int cpupid; |
| |
| if (PageError(page)) |
| SetPageError(newpage); |
| if (PageReferenced(page)) |
| SetPageReferenced(newpage); |
| if (PageUptodate(page)) |
| SetPageUptodate(newpage); |
| if (TestClearPageActive(page)) { |
| VM_BUG_ON_PAGE(PageUnevictable(page), page); |
| SetPageActive(newpage); |
| } else if (TestClearPageUnevictable(page)) |
| SetPageUnevictable(newpage); |
| if (PageChecked(page)) |
| SetPageChecked(newpage); |
| if (PageMappedToDisk(page)) |
| SetPageMappedToDisk(newpage); |
| |
| /* Move dirty on pages not done by migrate_page_move_mapping() */ |
| if (PageDirty(page)) |
| SetPageDirty(newpage); |
| |
| if (page_is_young(page)) |
| set_page_young(newpage); |
| if (page_is_idle(page)) |
| set_page_idle(newpage); |
| |
| /* |
| * Copy NUMA information to the new page, to prevent over-eager |
| * future migrations of this same page. |
| */ |
| cpupid = page_cpupid_xchg_last(page, -1); |
| page_cpupid_xchg_last(newpage, cpupid); |
| |
| ksm_migrate_page(newpage, page); |
| /* |
| * Please do not reorder this without considering how mm/ksm.c's |
| * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). |
| */ |
| if (PageSwapCache(page)) |
| ClearPageSwapCache(page); |
| ClearPagePrivate(page); |
| set_page_private(page, 0); |
| |
| /* |
| * If any waiters have accumulated on the new page then |
| * wake them up. |
| */ |
| if (PageWriteback(newpage)) |
| end_page_writeback(newpage); |
| |
| copy_page_owner(page, newpage); |
| |
| mem_cgroup_migrate(page, newpage); |
| } |
| EXPORT_SYMBOL(migrate_page_states); |
| |
| void migrate_page_copy(struct page *newpage, struct page *page) |
| { |
| if (PageHuge(page) || PageTransHuge(page)) |
| copy_huge_page(newpage, page); |
| else |
| copy_highpage(newpage, page); |
| |
| migrate_page_states(newpage, page); |
| } |
| EXPORT_SYMBOL(migrate_page_copy); |
| |
| /************************************************************ |
| * Migration functions |
| ***********************************************************/ |
| |
| /* |
| * Common logic to directly migrate a single LRU page suitable for |
| * pages that do not use PagePrivate/PagePrivate2. |
| * |
| * Pages are locked upon entry and exit. |
| */ |
| int migrate_page(struct address_space *mapping, |
| struct page *newpage, struct page *page, |
| enum migrate_mode mode) |
| { |
| int rc; |
| |
| BUG_ON(PageWriteback(page)); /* Writeback must be complete */ |
| |
| rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); |
| |
| if (rc != MIGRATEPAGE_SUCCESS) |
| return rc; |
| |
| if (mode != MIGRATE_SYNC_NO_COPY) |
| migrate_page_copy(newpage, page); |
| else |
| migrate_page_states(newpage, page); |
| return MIGRATEPAGE_SUCCESS; |
| } |
| EXPORT_SYMBOL(migrate_page); |
| |
| #ifdef CONFIG_BLOCK |
| /* |
| * Migration function for pages with buffers. This function can only be used |
| * if the underlying filesystem guarantees that no other references to "page" |
| * exist. |
| */ |
| int buffer_migrate_page(struct address_space *mapping, |
| struct page *newpage, struct page *page, enum migrate_mode mode) |
| { |
| struct buffer_head *bh, *head; |
| int rc; |
| |
| if (!page_has_buffers(page)) |
| return migrate_page(mapping, newpage, page, mode); |
| |
| head = page_buffers(page); |
| |
| rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); |
| |
| if (rc != MIGRATEPAGE_SUCCESS) |
| return rc; |
| |
| /* |
| * In the async case, migrate_page_move_mapping locked the buffers |
| * with an IRQ-safe spinlock held. In the sync case, the buffers |
| * need to be locked now |
| */ |
| if (mode != MIGRATE_ASYNC) |
| BUG_ON(!buffer_migrate_lock_buffers(head, mode)); |
| |
| ClearPagePrivate(page); |
| set_page_private(newpage, page_private(page)); |
| set_page_private(page, 0); |
| put_page(page); |
| get_page(newpage); |
| |
| bh = head; |
| do { |
| set_bh_page(bh, newpage, bh_offset(bh)); |
| bh = bh->b_this_page; |
| |
| } while (bh != head); |
| |
| SetPagePrivate(newpage); |
| |
| if (mode != MIGRATE_SYNC_NO_COPY) |
| migrate_page_copy(newpage, page); |
| else |
| migrate_page_states(newpage, page); |
| |
| bh = head; |
| do { |
| unlock_buffer(bh); |
| put_bh(bh); |
| bh = bh->b_this_page; |
| |
| } while (bh != head); |
| |
| return MIGRATEPAGE_SUCCESS; |
| } |
| EXPORT_SYMBOL(buffer_migrate_page); |
| #endif |
| |
| /* |
| * Writeback a page to clean the dirty state |
| */ |
| static int writeout(struct address_space *mapping, struct page *page) |
| { |
| 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 (!clear_page_dirty_for_io(page)) |
| /* Someone else already triggered a write */ |
| return -EAGAIN; |
| |
| /* |
| * A dirty page may imply that the underlying filesystem has |
| * the page on some queue. So the page must be clean for |
| * migration. Writeout may mean we loose the lock and the |
| * page state is no longer what we checked for earlier. |
| * At this point we know that the migration attempt cannot |
| * be successful. |
| */ |
| remove_migration_ptes(page, page, false); |
| |
| rc = mapping->a_ops->writepage(page, &wbc); |
| |
| if (rc != AOP_WRITEPAGE_ACTIVATE) |
| /* unlocked. Relock */ |
| lock_page(page); |
| |
| return (rc < 0) ? -EIO : -EAGAIN; |
| } |
| |
| /* |
| * Default handling if a filesystem does not provide a migration function. |
| */ |
| static int fallback_migrate_page(struct address_space *mapping, |
| struct page *newpage, struct page *page, enum migrate_mode mode) |
| { |
| if (PageDirty(page)) { |
| /* Only writeback pages in full synchronous migration */ |
| switch (mode) { |
| case MIGRATE_SYNC: |
| case MIGRATE_SYNC_NO_COPY: |
| break; |
| default: |
| return -EBUSY; |
| } |
| return writeout(mapping, page); |
| } |
| |
| /* |
| * Buffers may be managed in a filesystem specific way. |
| * We must have no buffers or drop them. |
| */ |
| if (page_has_private(page) && |
| !try_to_release_page(page, GFP_KERNEL)) |
| return -EAGAIN; |
| |
| return migrate_page(mapping, newpage, page, 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_page(struct page *newpage, struct page *page, |
| enum migrate_mode mode) |
| { |
| struct address_space *mapping; |
| int rc = -EAGAIN; |
| bool is_lru = !__PageMovable(page); |
| |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); |
| |
| mapping = page_mapping(page); |
| |
| if (likely(is_lru)) { |
| if (!mapping) |
| rc = migrate_page(mapping, newpage, page, mode); |
| else if (mapping->a_ops->migratepage) |
| /* |
| * Most pages have a mapping and most filesystems |
| * provide a migratepage callback. Anonymous pages |
| * are part of swap space which also has its own |
| * migratepage callback. This is the most common path |
| * for page migration. |
| */ |
| rc = mapping->a_ops->migratepage(mapping, newpage, |
| page, mode); |
| else |
| rc = fallback_migrate_page(mapping, newpage, |
| page, mode); |
| } else { |
| /* |
| * In case of non-lru page, it could be released after |
| * isolation step. In that case, we shouldn't try migration. |
| */ |
| VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| if (!PageMovable(page)) { |
| rc = MIGRATEPAGE_SUCCESS; |
| __ClearPageIsolated(page); |
| goto out; |
| } |
| |
| rc = mapping->a_ops->migratepage(mapping, newpage, |
| page, mode); |
| WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && |
| !PageIsolated(page)); |
| } |
| |
| /* |
| * When successful, old pagecache page->mapping must be cleared before |
| * page is freed; but stats require that PageAnon be left as PageAnon. |
| */ |
| if (rc == MIGRATEPAGE_SUCCESS) { |
| if (__PageMovable(page)) { |
| VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| |
| /* |
| * We clear PG_movable under page_lock so any compactor |
| * cannot try to migrate this page. |
| */ |
| __ClearPageIsolated(page); |
| } |
| |
| /* |
| * Anonymous and movable page->mapping will be cleard by |
| * free_pages_prepare so don't reset it here for keeping |
| * the type to work PageAnon, for example. |
| */ |
| if (!PageMappingFlags(page)) |
| page->mapping = NULL; |
| } |
| out: |
| return rc; |
| } |
| |
| static int __unmap_and_move(struct page *page, struct page *newpage, |
| int force, enum migrate_mode mode) |
| { |
| int rc = -EAGAIN; |
| int page_was_mapped = 0; |
| struct anon_vma *anon_vma = NULL; |
| bool is_lru = !__PageMovable(page); |
| |
| if (!trylock_page(page)) { |
| if (!force || 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_readpages). 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; |
| |
| lock_page(page); |
| } |
| |
| if (PageWriteback(page)) { |
| /* |
| * 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_unlock; |
| } |
| if (!force) |
| goto out_unlock; |
| wait_on_page_writeback(page); |
| } |
| |
| /* |
| * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
| * we cannot notice that anon_vma is freed while we migrates 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 page_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 (PageAnon(page) && !PageKsm(page)) |
| anon_vma = page_get_anon_vma(page); |
| |
| /* |
| * 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 newpage at this point. We used to have a BUG |
| * here if trylock_page(newpage) fails, but would like to allow for |
| * cases where there might be a race with the previous use of newpage. |
| * This is much like races on refcount of oldpage: just don't BUG(). |
| */ |
| if (unlikely(!trylock_page(newpage))) |
| goto out_unlock; |
| |
| if (unlikely(!is_lru)) { |
| rc = move_to_new_page(newpage, page, mode); |
| goto out_unlock_both; |
| } |
| |
| /* |
| * 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 page->mapping==NULL page will |
| * trigger a BUG. So handle it here. |
| * 2. An orphaned page (see truncate_complete_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 (!page->mapping) { |
| VM_BUG_ON_PAGE(PageAnon(page), page); |
| if (page_has_private(page)) { |
| try_to_free_buffers(page); |
| goto out_unlock_both; |
| } |
| } else if (page_mapped(page)) { |
| /* Establish migration ptes */ |
| VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma, |
| page); |
| try_to_unmap(page, |
| TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| page_was_mapped = 1; |
| } |
| |
| if (!page_mapped(page)) |
| rc = move_to_new_page(newpage, page, mode); |
| |
| if (page_was_mapped) |
| remove_migration_ptes(page, |
| rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); |
| |
| out_unlock_both: |
| unlock_page(newpage); |
| out_unlock: |
| /* Drop an anon_vma reference if we took one */ |
| if (anon_vma) |
| put_anon_vma(anon_vma); |
| unlock_page(page); |
| out: |
| /* |
| * If migration is successful, decrease refcount of the newpage |
| * which will not free the page because new page owner increased |
| * refcounter. As well, if it is LRU page, add the page to LRU |
| * list in here. |
| */ |
| if (rc == MIGRATEPAGE_SUCCESS) { |
| if (unlikely(__PageMovable(newpage))) |
| put_page(newpage); |
| else |
| putback_lru_page(newpage); |
| } |
| |
| return rc; |
| } |
| |
| /* |
| * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work |
| * around it. |
| */ |
| #if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM) |
| #define ICE_noinline noinline |
| #else |
| #define ICE_noinline |
| #endif |
| |
| /* |
| * Obtain the lock on page, remove all ptes and migrate the page |
| * to the newly allocated page in newpage. |
| */ |
| static ICE_noinline int unmap_and_move(new_page_t get_new_page, |
| free_page_t put_new_page, |
| unsigned long private, struct page *page, |
| int force, enum migrate_mode mode, |
| enum migrate_reason reason) |
| { |
| int rc = MIGRATEPAGE_SUCCESS; |
| int *result = NULL; |
| struct page *newpage; |
| |
| newpage = get_new_page(page, private, &result); |
| if (!newpage) |
| return -ENOMEM; |
| |
| if (page_count(page) == 1) { |
| /* page was freed from under us. So we are done. */ |
| ClearPageActive(page); |
| ClearPageUnevictable(page); |
| if (unlikely(__PageMovable(page))) { |
| lock_page(page); |
| if (!PageMovable(page)) |
| __ClearPageIsolated(page); |
| unlock_page(page); |
| } |
| if (put_new_page) |
| put_new_page(newpage, private); |
| else |
| put_page(newpage); |
| goto out; |
| } |
| |
| if (unlikely(PageTransHuge(page) && !PageTransHuge(newpage))) { |
| lock_page(page); |
| rc = split_huge_page(page); |
| unlock_page(page); |
| if (rc) |
| goto out; |
| } |
| |
| rc = __unmap_and_move(page, newpage, force, mode); |
| if (rc == MIGRATEPAGE_SUCCESS) |
| set_page_owner_migrate_reason(newpage, reason); |
| |
| out: |
| if (rc != -EAGAIN) { |
| /* |
| * A page that has been migrated has all references |
| * removed and will be freed. A page that has not been |
| * migrated will have kepts its references and be |
| * restored. |
| */ |
| list_del(&page->lru); |
| |
| /* |
| * Compaction can migrate also non-LRU pages which are |
| * not accounted to NR_ISOLATED_*. They can be recognized |
| * as __PageMovable |
| */ |
| if (likely(!__PageMovable(page))) |
| mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + |
| page_is_file_cache(page), -hpage_nr_pages(page)); |
| } |
| |
| /* |
| * If migration is successful, releases reference grabbed during |
| * isolation. Otherwise, restore the page to right list unless |
| * we want to retry. |
| */ |
| if (rc == MIGRATEPAGE_SUCCESS) { |
| put_page(page); |
| if (reason == MR_MEMORY_FAILURE) { |
| /* |
| * Set PG_HWPoison on just freed page |
| * intentionally. Although it's rather weird, |
| * it's how HWPoison flag works at the moment. |
| */ |
| if (!test_set_page_hwpoison(page)) |
| num_poisoned_pages_inc(); |
| } |
| } else { |
| if (rc != -EAGAIN) { |
| if (likely(!__PageMovable(page))) { |
| putback_lru_page(page); |
| goto put_new; |
| } |
| |
| lock_page(page); |
| if (PageMovable(page)) |
| putback_movable_page(page); |
| else |
| __ClearPageIsolated(page); |
| unlock_page(page); |
| put_page(page); |
| } |
| put_new: |
| if (put_new_page) |
| put_new_page(newpage, private); |
| else |
| put_page(newpage); |
| } |
| |
| if (result) { |
| if (rc) |
| *result = rc; |
| else |
| *result = page_to_nid(newpage); |
| } |
| 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_page_t get_new_page, |
| free_page_t put_new_page, unsigned long private, |
| struct page *hpage, int force, |
| enum migrate_mode mode, int reason) |
| { |
| int rc = -EAGAIN; |
| int *result = NULL; |
| int page_was_mapped = 0; |
| struct page *new_hpage; |
| struct anon_vma *anon_vma = NULL; |
| |
| /* |
| * Movability of hugepages depends on architectures and hugepage 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(page_hstate(hpage))) { |
| putback_active_hugepage(hpage); |
| return -ENOSYS; |
| } |
| |
| new_hpage = get_new_page(hpage, private, &result); |
| if (!new_hpage) |
| return -ENOMEM; |
| |
| if (!trylock_page(hpage)) { |
| if (!force) |
| goto out; |
| switch (mode) { |
| case MIGRATE_SYNC: |
| case MIGRATE_SYNC_NO_COPY: |
| break; |
| default: |
| goto out; |
| } |
| lock_page(hpage); |
| } |
| |
| if (PageAnon(hpage)) |
| anon_vma = page_get_anon_vma(hpage); |
| |
| if (unlikely(!trylock_page(new_hpage))) |
| goto put_anon; |
| |
| if (page_mapped(hpage)) { |
| try_to_unmap(hpage, |
| TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| page_was_mapped = 1; |
| } |
| |
| if (!page_mapped(hpage)) |
| rc = move_to_new_page(new_hpage, hpage, mode); |
| |
| if (page_was_mapped) |
| remove_migration_ptes(hpage, |
| rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false); |
| |
| unlock_page(new_hpage); |
| |
| put_anon: |
| if (anon_vma) |
| put_anon_vma(anon_vma); |
| |
| if (rc == MIGRATEPAGE_SUCCESS) { |
| hugetlb_cgroup_migrate(hpage, new_hpage); |
| put_new_page = NULL; |
| set_page_owner_migrate_reason(new_hpage, reason); |
| } |
| |
| unlock_page(hpage); |
| out: |
| if (rc != -EAGAIN) |
| putback_active_hugepage(hpage); |
| if (reason == MR_MEMORY_FAILURE && !test_set_page_hwpoison(hpage)) |
| num_poisoned_pages_inc(); |
| |
| /* |
| * 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_page) |
| put_new_page(new_hpage, private); |
| else |
| putback_active_hugepage(new_hpage); |
| |
| if (result) { |
| if (rc) |
| *result = rc; |
| else |
| *result = page_to_nid(new_hpage); |
| } |
| return rc; |
| } |
| |
| /* |
| * migrate_pages - migrate the pages specified in a list, to the free pages |
| * supplied as the target for the page migration |
| * |
| * @from: The list of pages to be migrated. |
| * @get_new_page: The function used to allocate free pages to be used |
| * as the target of the page migration. |
| * @put_new_page: The function used to free target pages if migration |
| * fails, or NULL if no special handling is necessary. |
| * @private: Private data to be passed on to get_new_page() |
| * @mode: The migration mode that specifies the constraints for |
| * page migration, if any. |
| * @reason: The reason for page migration. |
| * |
| * The function returns after 10 attempts or if no pages are movable any more |
| * because the list has become empty or no retryable pages exist any more. |
| * The caller should call putback_movable_pages() to return pages to the LRU |
| * or free list only if ret != 0. |
| * |
| * Returns the number of pages that were not migrated, or an error code. |
| */ |
| int migrate_pages(struct list_head *from, new_page_t get_new_page, |
| free_page_t put_new_page, unsigned long private, |
| enum migrate_mode mode, int reason) |
| { |
| int retry = 1; |
| int nr_failed = 0; |
| int nr_succeeded = 0; |
| int pass = 0; |
| struct page *page; |
| struct page *page2; |
| int swapwrite = current->flags & PF_SWAPWRITE; |
| int rc; |
| |
| if (!swapwrite) |
| current->flags |= PF_SWAPWRITE; |
| |
| for(pass = 0; pass < 10 && retry; pass++) { |
| retry = 0; |
| |
| list_for_each_entry_safe(page, page2, from, lru) { |
| cond_resched(); |
| |
| if (PageHuge(page)) |
| rc = unmap_and_move_huge_page(get_new_page, |
| put_new_page, private, page, |
| pass > 2, mode, reason); |
| else |
| rc = unmap_and_move(get_new_page, put_new_page, |
| private, page, pass > 2, mode, |
| reason); |
| |
| switch(rc) { |
| case -ENOMEM: |
| nr_failed++; |
| goto out; |
| case -EAGAIN: |
| retry++; |
| break; |
| case MIGRATEPAGE_SUCCESS: |
| nr_succeeded++; |
| break; |
| default: |
| /* |
| * Permanent failure (-EBUSY, -ENOSYS, etc.): |
| * unlike -EAGAIN case, the failed page is |
| * removed from migration page list and not |
| * retried in the next outer loop. |
| */ |
| nr_failed++; |
| break; |
| } |
| } |
| } |
| nr_failed += retry; |
| rc = nr_failed; |
| out: |
| if (nr_succeeded) |
| count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); |
| if (nr_failed) |
| count_vm_events(PGMIGRATE_FAIL, nr_failed); |
| trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); |
| |
| if (!swapwrite) |
| current->flags &= ~PF_SWAPWRITE; |
| |
| return rc; |
| } |
| |
| #ifdef CONFIG_NUMA |
| /* |
| * Move a list of individual pages |
| */ |
| struct page_to_node { |
| unsigned long addr; |
| struct page *page; |
| int node; |
| int status; |
| }; |
| |
| static struct page *new_page_node(struct page *p, unsigned long private, |
| int **result) |
| { |
| struct page_to_node *pm = (struct page_to_node *)private; |
| |
| while (pm->node != MAX_NUMNODES && pm->page != p) |
| pm++; |
| |
| if (pm->node == MAX_NUMNODES) |
| return NULL; |
| |
| *result = &pm->status; |
| |
| if (PageHuge(p)) |
| return alloc_huge_page_node(page_hstate(compound_head(p)), |
| pm->node); |
| else if (thp_migration_supported() && PageTransHuge(p)) { |
| struct page *thp; |
| |
| thp = alloc_pages_node(pm->node, |
| (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_RECLAIM, |
| HPAGE_PMD_ORDER); |
| if (!thp) |
| return NULL; |
| prep_transhuge_page(thp); |
| return thp; |
| } else |
| return __alloc_pages_node(pm->node, |
| GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0); |
| } |
| |
| /* |
| * Move a set of pages as indicated in the pm array. The addr |
| * field must be set to the virtual address of the page to be moved |
| * and the node number must contain a valid target node. |
| * The pm array ends with node = MAX_NUMNODES. |
| */ |
| static int do_move_page_to_node_array(struct mm_struct *mm, |
| struct page_to_node *pm, |
| int migrate_all) |
| { |
| int err; |
| struct page_to_node *pp; |
| LIST_HEAD(pagelist); |
| |
| down_read(&mm->mmap_sem); |
| |
| /* |
| * Build a list of pages to migrate |
| */ |
| for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
| struct vm_area_struct *vma; |
| struct page *page; |
| struct page *head; |
| unsigned int follflags; |
| |
| err = -EFAULT; |
| vma = find_vma(mm, pp->addr); |
| if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) |
| goto set_status; |
| |
| /* FOLL_DUMP to ignore special (like zero) pages */ |
| follflags = FOLL_GET | FOLL_DUMP; |
| if (!thp_migration_supported()) |
| follflags |= FOLL_SPLIT; |
| page = follow_page(vma, pp->addr, follflags); |
| |
| err = PTR_ERR(page); |
| if (IS_ERR(page)) |
| goto set_status; |
| |
| err = -ENOENT; |
| if (!page) |
| goto set_status; |
| |
| err = page_to_nid(page); |
| |
| if (err == pp->node) |
| /* |
| * Node already in the right place |
| */ |
| goto put_and_set; |
| |
| err = -EACCES; |
| if (page_mapcount(page) > 1 && |
| !migrate_all) |
| goto put_and_set; |
| |
| if (PageHuge(page)) { |
| if (PageHead(page)) { |
| isolate_huge_page(page, &pagelist); |
| err = 0; |
| pp->page = page; |
| } |
| goto put_and_set; |
| } |
| |
| pp->page = compound_head(page); |
| head = compound_head(page); |
| err = isolate_lru_page(head); |
| if (!err) { |
| list_add_tail(&head->lru, &pagelist); |
| mod_node_page_state(page_pgdat(head), |
| NR_ISOLATED_ANON + page_is_file_cache(head), |
| hpage_nr_pages(head)); |
| } |
| put_and_set: |
| /* |
| * Either remove the duplicate refcount from |
| * isolate_lru_page() or drop the page ref if it was |
| * not isolated. |
| */ |
| put_page(page); |
| set_status: |
| pp->status = err; |
| } |
| |
| err = 0; |
| if (!list_empty(&pagelist)) { |
| err = migrate_pages(&pagelist, new_page_node, NULL, |
| (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); |
| if (err) |
| putback_movable_pages(&pagelist); |
| } |
| |
| up_read(&mm->mmap_sem); |
| return err; |
| } |
| |
| /* |
| * 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) |
| { |
| struct page_to_node *pm; |
| unsigned long chunk_nr_pages; |
| unsigned long chunk_start; |
| int err; |
| |
| err = -ENOMEM; |
| pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); |
| if (!pm) |
| goto out; |
| |
| migrate_prep(); |
| |
| /* |
| * Store a chunk of page_to_node array in a page, |
| * but keep the last one as a marker |
| */ |
| chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
| |
| for (chunk_start = 0; |
| chunk_start < nr_pages; |
| chunk_start += chunk_nr_pages) { |
| int j; |
| |
| if (chunk_start + chunk_nr_pages > nr_pages) |
| chunk_nr_pages = nr_pages - chunk_start; |
| |
| /* fill the chunk pm with addrs and nodes from user-space */ |
| for (j = 0; j < chunk_nr_pages; j++) { |
| const void __user *p; |
| int node; |
| |
| err = -EFAULT; |
| if (get_user(p, pages + j + chunk_start)) |
| goto out_pm; |
| pm[j].addr = (unsigned long) p; |
| |
| if (get_user(node, nodes + j + chunk_start)) |
| goto out_pm; |
| |
| err = -ENODEV; |
| if (node < 0 || node >= MAX_NUMNODES) |
| goto out_pm; |
| |
| if (!node_state(node, N_MEMORY)) |
| goto out_pm; |
| |
| err = -EACCES; |
| if (!node_isset(node, task_nodes)) |
| goto out_pm; |
| |
| pm[j].node = node; |
| } |
| |
| /* End marker for this chunk */ |
| pm[chunk_nr_pages].node = MAX_NUMNODES; |
| |
| /* Migrate this chunk */ |
| err = do_move_page_to_node_array(mm, pm, |
| flags & MPOL_MF_MOVE_ALL); |
| if (err < 0) |
| goto out_pm; |
| |
| /* Return status information */ |
| for (j = 0; j < chunk_nr_pages; j++) |
| if (put_user(pm[j].status, status + j + chunk_start)) { |
| err = -EFAULT; |
| goto out_pm; |
| } |
| } |
| err = 0; |
| |
| out_pm: |
| free_page((unsigned long)pm); |
| out: |
| 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; |
| |
| down_read(&mm->mmap_sem); |
| |
| 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 = find_vma(mm, addr); |
| if (!vma || addr < vma->vm_start) |
| goto set_status; |
| |
| /* FOLL_DUMP to ignore special (like zero) pages */ |
| page = follow_page(vma, addr, FOLL_DUMP); |
| |
| err = PTR_ERR(page); |
| if (IS_ERR(page)) |
| goto set_status; |
| |
| err = page ? page_to_nid(page) : -ENOENT; |
| set_status: |
| *status = err; |
| |
| pages++; |
| status++; |
| } |
| |
| up_read(&mm->mmap_sem); |
| } |
| |
| /* |
| * 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 16 |
| 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; |
| |
| chunk_nr = nr_pages; |
| if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) |
| chunk_nr = DO_PAGES_STAT_CHUNK_NR; |
| |
| 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; |
| } |
| |
| /* |
| * Move a list of pages in the address space of the currently executing |
| * process. |
| */ |
| 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) |
| { |
| struct task_struct *task; |
| 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; |
| |
| /* Find the mm_struct */ |
| rcu_read_lock(); |
| task = pid ? find_task_by_vpid(pid) : current; |
| if (!task) { |
| rcu_read_unlock(); |
| return -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(); |
| err = -EPERM; |
| goto out; |
| } |
| rcu_read_unlock(); |
| |
| err = security_task_movememory(task); |
| if (err) |
| goto out; |
| |
| task_nodes = cpuset_mems_allowed(task); |
| mm = get_task_mm(task); |
| put_task_struct(task); |
| |
| if (!mm) |
| return -EINVAL; |
| |
| 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; |
| |
| out: |
| put_task_struct(task); |
| return err; |
| } |
| |
| #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 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 (!populated_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, |
| 0, 0)) |
| continue; |
| return true; |
| } |
| return false; |
| } |
| |
| static struct page *alloc_misplaced_dst_page(struct page *page, |
| unsigned long data, |
| int **result) |
| { |
| int nid = (int) data; |
| struct page *newpage; |
| |
| newpage = __alloc_pages_node(nid, |
| (GFP_HIGHUSER_MOVABLE | |
| __GFP_THISNODE | __GFP_NOMEMALLOC | |
| __GFP_NORETRY | __GFP_NOWARN) & |
| ~__GFP_RECLAIM, 0); |
| |
| return newpage; |
| } |
| |
| /* |
| * page migration rate limiting control. |
| * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs |
| * window of time. Default here says do not migrate more than 1280M per second. |
| */ |
| static unsigned int migrate_interval_millisecs __read_mostly = 100; |
| static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); |
| |
| /* Returns true if the node is migrate rate-limited after the update */ |
| static bool numamigrate_update_ratelimit(pg_data_t *pgdat, |
| unsigned long nr_pages) |
| { |
| /* |
| * Rate-limit the amount of data that is being migrated to a node. |
| * Optimal placement is no good if the memory bus is saturated and |
| * all the time is being spent migrating! |
| */ |
| if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { |
| spin_lock(&pgdat->numabalancing_migrate_lock); |
| pgdat->numabalancing_migrate_nr_pages = 0; |
| pgdat->numabalancing_migrate_next_window = jiffies + |
| msecs_to_jiffies(migrate_interval_millisecs); |
| spin_unlock(&pgdat->numabalancing_migrate_lock); |
| } |
| if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { |
| trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, |
| nr_pages); |
| return true; |
| } |
| |
| /* |
| * This is an unlocked non-atomic update so errors are possible. |
| * The consequences are failing to migrate when we potentiall should |
| * have which is not severe enough to warrant locking. If it is ever |
| * a problem, it can be converted to a per-cpu counter. |
| */ |
| pgdat->numabalancing_migrate_nr_pages += nr_pages; |
| return false; |
| } |
| |
| static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) |
| { |
| int page_lru; |
| |
| VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); |
| |
| /* Avoid migrating to a node that is nearly full */ |
| if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) |
| return 0; |
| |
| if (isolate_lru_page(page)) |
| return 0; |
| |
| /* |
| * migrate_misplaced_transhuge_page() skips page migration's usual |
| * check on page_count(), so we must do it here, now that the page |
| * has been isolated: a GUP pin, or any other pin, prevents migration. |
| * The expected page count is 3: 1 for page's mapcount and 1 for the |
| * caller's pin and 1 for the reference taken by isolate_lru_page(). |
| */ |
| if (PageTransHuge(page) && page_count(page) != 3) { |
| putback_lru_page(page); |
| return 0; |
| } |
| |
| page_lru = page_is_file_cache(page); |
| mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, |
| hpage_nr_pages(page)); |
| |
| /* |
| * 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; |
| } |
| |
| bool pmd_trans_migrating(pmd_t pmd) |
| { |
| struct page *page = pmd_page(pmd); |
| return PageLocked(page); |
| } |
| |
| /* |
| * 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; |
| LIST_HEAD(migratepages); |
| |
| /* |
| * 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_cache(page) && |
| (vma->vm_flags & VM_EXEC)) |
| goto out; |
| |
| /* |
| * Rate-limit the amount of data that is being migrated to a node. |
| * Optimal placement is no good if the memory bus is saturated and |
| * all the time is being spent migrating! |
| */ |
| if (numamigrate_update_ratelimit(pgdat, 1)) |
| 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_page, |
| NULL, node, MIGRATE_ASYNC, |
| MR_NUMA_MISPLACED); |
| if (nr_remaining) { |
| if (!list_empty(&migratepages)) { |
| list_del(&page->lru); |
| dec_node_page_state(page, NR_ISOLATED_ANON + |
| page_is_file_cache(page)); |
| putback_lru_page(page); |
| } |
| isolated = 0; |
| } else |
| count_vm_numa_event(NUMA_PAGE_MIGRATE); |
| BUG_ON(!list_empty(&migratepages)); |
| return isolated; |
| |
| out: |
| put_page(page); |
| return 0; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) |
| /* |
| * Migrates a THP to a given target node. page must be locked and is unlocked |
| * before returning. |
| */ |
| int migrate_misplaced_transhuge_page(struct mm_struct *mm, |
| struct vm_area_struct *vma, |
| pmd_t *pmd, pmd_t entry, |
| unsigned long address, |
| struct page *page, int node) |
| { |
| spinlock_t *ptl; |
| pg_data_t *pgdat = NODE_DATA(node); |
| int isolated = 0; |
| struct page *new_page = NULL; |
| int page_lru = page_is_file_cache(page); |
| unsigned long mmun_start = address & HPAGE_PMD_MASK; |
| unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; |
| |
| /* |
| * Rate-limit the amount of data that is being migrated to a node. |
| * Optimal placement is no good if the memory bus is saturated and |
| * all the time is being spent migrating! |
| */ |
| if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) |
| goto out_dropref; |
| |
| new_page = alloc_pages_node(node, |
| (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), |
| HPAGE_PMD_ORDER); |
| if (!new_page) |
| goto out_fail; |
| prep_transhuge_page(new_page); |
| |
| isolated = numamigrate_isolate_page(pgdat, page); |
| if (!isolated) { |
| put_page(new_page); |
| goto out_fail; |
| } |
| |
| /* Prepare a page as a migration target */ |
| __SetPageLocked(new_page); |
| if (PageSwapBacked(page)) |
| __SetPageSwapBacked(new_page); |
| |
| /* anon mapping, we can simply copy page->mapping to the new page: */ |
| new_page->mapping = page->mapping; |
| new_page->index = page->index; |
| migrate_page_copy(new_page, page); |
| WARN_ON(PageLRU(new_page)); |
| |
| /* Recheck the target PMD */ |
| mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| ptl = pmd_lock(mm, pmd); |
| if (unlikely(!pmd_same(*pmd, entry) || !page_ref_freeze(page, 2))) { |
| spin_unlock(ptl); |
| mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| |
| /* Reverse changes made by migrate_page_copy() */ |
| if (TestClearPageActive(new_page)) |
| SetPageActive(page); |
| if (TestClearPageUnevictable(new_page)) |
| SetPageUnevictable(page); |
| |
| unlock_page(new_page); |
| put_page(new_page); /* Free it */ |
| |
| /* Retake the callers reference and putback on LRU */ |
| get_page(page); |
| putback_lru_page(page); |
| mod_node_page_state(page_pgdat(page), |
| NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); |
| |
| goto out_unlock; |
| } |
| |
| entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
| entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| |
| /* |
| * Clear the old entry under pagetable lock and establish the new PTE. |
| * Any parallel GUP will either observe the old page blocking on the |
| * page lock, block on the page table lock or observe the new page. |
| * The SetPageUptodate on the new page and page_add_new_anon_rmap |
| * guarantee the copy is visible before the pagetable update. |
| */ |
| flush_cache_range(vma, mmun_start, mmun_end); |
| page_add_anon_rmap(new_page, vma, mmun_start, true); |
| pmdp_huge_clear_flush_notify(vma, mmun_start, pmd); |
| set_pmd_at(mm, mmun_start, pmd, entry); |
| update_mmu_cache_pmd(vma, address, &entry); |
| |
| page_ref_unfreeze(page, 2); |
| mlock_migrate_page(new_page, page); |
| page_remove_rmap(page, true); |
| set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); |
| |
| spin_unlock(ptl); |
| mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| |
| /* Take an "isolate" reference and put new page on the LRU. */ |
| get_page(new_page); |
| putback_lru_page(new_page); |
| |
| unlock_page(new_page); |
| unlock_page(page); |
| put_page(page); /* Drop the rmap reference */ |
| put_page(page); /* Drop the LRU isolation reference */ |
| |
| count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); |
| count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); |
| |
| mod_node_page_state(page_pgdat(page), |
| NR_ISOLATED_ANON + page_lru, |
| -HPAGE_PMD_NR); |
| return isolated; |
| |
| out_fail: |
| count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); |
| out_dropref: |
| ptl = pmd_lock(mm, pmd); |
| if (pmd_same(*pmd, entry)) { |
| entry = pmd_modify(entry, vma->vm_page_prot); |
| set_pmd_at(mm, mmun_start, pmd, entry); |
| update_mmu_cache_pmd(vma, address, &entry); |
| } |
| spin_unlock(ptl); |
| |
| out_unlock: |
| unlock_page(page); |
| put_page(page); |
| return 0; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| #endif /* CONFIG_NUMA */ |
| |
| #if defined(CONFIG_MIGRATE_VMA_HELPER) |
| struct migrate_vma { |
| struct vm_area_struct *vma; |
| unsigned long *dst; |
| unsigned long *src; |
| unsigned long cpages; |
| unsigned long npages; |
| unsigned long start; |
| unsigned long end; |
| }; |
| |
| static int migrate_vma_collect_hole(unsigned long start, |
| unsigned long end, |
| struct mm_walk *walk) |
| { |
| struct migrate_vma *migrate = walk->private; |
| unsigned long addr; |
| |
| for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) { |
| migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE; |
| migrate->dst[migrate->npages] = 0; |
| migrate->npages++; |
| migrate->cpages++; |
| } |
| |
| return 0; |
| } |
| |
| static int migrate_vma_collect_skip(unsigned long start, |
| unsigned long end, |
| struct mm_walk *walk) |
| { |
| struct migrate_vma *migrate = walk->private; |
| unsigned long addr; |
| |
| for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) { |
| migrate->dst[migrate->npages] = 0; |
| migrate->src[migrate->npages++] = 0; |
| } |
| |
| return 0; |
| } |
| |
| static int migrate_vma_collect_pmd(pmd_t *pmdp, |
| unsigned long start, |
| unsigned long end, |
| struct mm_walk *walk) |
| { |
| struct migrate_vma *migrate = walk->private; |
| struct vm_area_struct *vma = walk->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long addr = start, unmapped = 0; |
| spinlock_t *ptl; |
| pte_t *ptep; |
| |
| again: |
| if (pmd_none(*pmdp)) |
| return migrate_vma_collect_hole(start, end, walk); |
| |
| if (pmd_trans_huge(*pmdp)) { |
| struct page *page; |
| |
| ptl = pmd_lock(mm, pmdp); |
| if (unlikely(!pmd_trans_huge(*pmdp))) { |
| spin_unlock(ptl); |
| goto again; |
| } |
| |
| page = pmd_page(*pmdp); |
| if (is_huge_zero_page(page)) { |
| spin_unlock(ptl); |
| split_huge_pmd(vma, pmdp, addr); |
| if (pmd_trans_unstable(pmdp)) |
| return migrate_vma_collect_skip(start, end, |
| walk); |
| } else { |
| int ret; |
| |
| get_page(page); |
| spin_unlock(ptl); |
| if (unlikely(!trylock_page(page))) |
| return migrate_vma_collect_skip(start, end, |
| walk); |
| ret = split_huge_page(page); |
| unlock_page(page); |
| put_page(page); |
| if (ret) |
| return migrate_vma_collect_skip(start, end, |
| walk); |
| if (pmd_none(*pmdp)) |
| return migrate_vma_collect_hole(start, end, |
| walk); |
| } |
| } |
| |
| if (unlikely(pmd_bad(*pmdp))) |
| return migrate_vma_collect_skip(start, end, walk); |
| |
| ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); |
| arch_enter_lazy_mmu_mode(); |
| |
| for (; addr < end; addr += PAGE_SIZE, ptep++) { |
| unsigned long mpfn, pfn; |
| struct page *page; |
| swp_entry_t entry; |
| pte_t pte; |
| |
| pte = *ptep; |
| pfn = pte_pfn(pte); |
| |
| if (pte_none(pte)) { |
| mpfn = MIGRATE_PFN_MIGRATE; |
| migrate->cpages++; |
| pfn = 0; |
| goto next; |
| } |
| |
| if (!pte_present(pte)) { |
| mpfn = pfn = 0; |
| |
| /* |
| * Only care about unaddressable device page special |
| * page table entry. Other special swap entries are not |
| * migratable, and we ignore regular swapped page. |
| */ |
| entry = pte_to_swp_entry(pte); |
| if (!is_device_private_entry(entry)) |
| goto next; |
| |
| page = device_private_entry_to_page(entry); |
| mpfn = migrate_pfn(page_to_pfn(page))| |
| MIGRATE_PFN_DEVICE | MIGRATE_PFN_MIGRATE; |
| if (is_write_device_private_entry(entry)) |
| mpfn |= MIGRATE_PFN_WRITE; |
| } else { |
| if (is_zero_pfn(pfn)) { |
| mpfn = MIGRATE_PFN_MIGRATE; |
| migrate->cpages++; |
| pfn = 0; |
| goto next; |
| } |
| page = _vm_normal_page(migrate->vma, addr, pte, true); |
| mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; |
| mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; |
| } |
| |
| /* FIXME support THP */ |
| if (!page || !page->mapping || PageTransCompound(page)) { |
| mpfn = pfn = 0; |
| goto next; |
| } |
| pfn = page_to_pfn(page); |
| |
| /* |
| * By getting a reference on the page we pin it and that blocks |
| * any kind of migration. Side effect is that it "freezes" the |
| * pte. |
| * |
| * We drop this reference after isolating the page from the lru |
| * for non device page (device page are not on the lru and thus |
| * can't be dropped from it). |
| */ |
| get_page(page); |
| migrate->cpages++; |
| |
| /* |
| * Optimize for the common case where page is only mapped once |
| * in one process. If we can lock the page, then we can safely |
| * set up a special migration page table entry now. |
| */ |
| if (trylock_page(page)) { |
| pte_t swp_pte; |
| |
| mpfn |= MIGRATE_PFN_LOCKED; |
| ptep_get_and_clear(mm, addr, ptep); |
| |
| /* Setup special migration page table entry */ |
| entry = make_migration_entry(page, pte_write(pte)); |
| swp_pte = swp_entry_to_pte(entry); |
| if (pte_soft_dirty(pte)) |
| swp_pte = pte_swp_mksoft_dirty(swp_pte); |
| set_pte_at(mm, addr, ptep, swp_pte); |
| |
| /* |
| * This is like regular unmap: we remove the rmap and |
| * drop page refcount. Page won't be freed, as we took |
| * a reference just above. |
| */ |
| page_remove_rmap(page, false); |
| put_page(page); |
| |
| if (pte_present(pte)) |
| unmapped++; |
| } |
| |
| next: |
| migrate->dst[migrate->npages] = 0; |
| migrate->src[migrate->npages++] = mpfn; |
| } |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(ptep - 1, ptl); |
| |
| /* Only flush the TLB if we actually modified any entries */ |
| if (unmapped) |
| flush_tlb_range(walk->vma, start, end); |
| |
| return 0; |
| } |
| |
| /* |
| * migrate_vma_collect() - collect pages over a range of virtual addresses |
| * @migrate: migrate struct containing all migration information |
| * |
| * This will walk the CPU page table. For each virtual address backed by a |
| * valid page, it updates the src array and takes a reference on the page, in |
| * order to pin the page until we lock it and unmap it. |
| */ |
| static void migrate_vma_collect(struct migrate_vma *migrate) |
| { |
| struct mm_walk mm_walk; |
| |
| mm_walk.pmd_entry = migrate_vma_collect_pmd; |
| mm_walk.pte_entry = NULL; |
| mm_walk.pte_hole = migrate_vma_collect_hole; |
| mm_walk.hugetlb_entry = NULL; |
| mm_walk.test_walk = NULL; |
| mm_walk.vma = migrate->vma; |
| mm_walk.mm = migrate->vma->vm_mm; |
| mm_walk.private = migrate; |
| |
| mmu_notifier_invalidate_range_start(mm_walk.mm, |
| migrate->start, |
| migrate->end); |
| walk_page_range(migrate->start, migrate->end, &mm_walk); |
| mmu_notifier_invalidate_range_end(mm_walk.mm, |
| migrate->start, |
| migrate->end); |
| |
| migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT); |
| } |
| |
| /* |
| * migrate_vma_check_page() - check if page is pinned or not |
| * @page: struct page to check |
| * |
| * Pinned pages cannot be migrated. This is the same test as in |
| * migrate_page_move_mapping(), except that here we allow migration of a |
| * ZONE_DEVICE page. |
| */ |
| static bool migrate_vma_check_page(struct page *page) |
| { |
| /* |
| * One extra ref because caller holds an extra reference, either from |
| * isolate_lru_page() for a regular page, or migrate_vma_collect() for |
| * a device page. |
| */ |
| int extra = 1; |
| |
| /* |
| * FIXME support THP (transparent huge page), it is bit more complex to |
| * check them than regular pages, because they can be mapped with a pmd |
| * or with a pte (split pte mapping). |
| */ |
| if (PageCompound(page)) |
| return false; |
| |
| /* Page from ZONE_DEVICE have one extra reference */ |
| if (is_zone_device_page(page)) { |
| /* |
| * Private page can never be pin as they have no valid pte and |
| * GUP will fail for those. Yet if there is a pending migration |
| * a thread might try to wait on the pte migration entry and |
| * will bump the page reference count. Sadly there is no way to |
| * differentiate a regular pin from migration wait. Hence to |
| * avoid 2 racing thread trying to migrate back to CPU to enter |
| * infinite loop (one stoping migration because the other is |
| * waiting on pte migration entry). We always return true here. |
| * |
| * FIXME proper solution is to rework migration_entry_wait() so |
| * it does not need to take a reference on page. |
| */ |
| if (is_device_private_page(page)) |
| return true; |
| |
| /* |
| * Only allow device public page to be migrated and account for |
| * the extra reference count imply by ZONE_DEVICE pages. |
| */ |
| if (!is_device_public_page(page)) |
| return false; |
| extra++; |
| } |
| |
| /* For file back page */ |
| if (page_mapping(page)) |
| extra += 1 + page_has_private(page); |
| |
| if ((page_count(page) - extra) > page_mapcount(page)) |
| return false; |
| |
| return true; |
| } |
| |
| /* |
| * migrate_vma_prepare() - lock pages and isolate them from the lru |
| * @migrate: migrate struct containing all migration information |
| * |
| * This locks pages that have been collected by migrate_vma_collect(). Once each |
| * page is locked it is isolated from the lru (for non-device pages). Finally, |
| * the ref taken by migrate_vma_collect() is dropped, as locked pages cannot be |
| * migrated by concurrent kernel threads. |
| */ |
| static void migrate_vma_prepare(struct migrate_vma *migrate) |
| { |
| const unsigned long npages = migrate->npages; |
| const unsigned long start = migrate->start; |
| unsigned long addr, i, restore = 0; |
| bool allow_drain = true; |
| |
| lru_add_drain(); |
| |
| for (i = 0; (i < npages) && migrate->cpages; i++) { |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| bool remap = true; |
| |
| if (!page) |
| continue; |
| |
| if (!(migrate->src[i] & MIGRATE_PFN_LOCKED)) { |
| /* |
| * Because we are migrating several pages there can be |
| * a deadlock between 2 concurrent migration where each |
| * are waiting on each other page lock. |
| * |
| * Make migrate_vma() a best effort thing and backoff |
| * for any page we can not lock right away. |
| */ |
| if (!trylock_page(page)) { |
| migrate->src[i] = 0; |
| migrate->cpages--; |
| put_page(page); |
| continue; |
| } |
| remap = false; |
| migrate->src[i] |= MIGRATE_PFN_LOCKED; |
| } |
| |
| /* ZONE_DEVICE pages are not on LRU */ |
| if (!is_zone_device_page(page)) { |
| if (!PageLRU(page) && allow_drain) { |
| /* Drain CPU's pagevec */ |
| lru_add_drain_all(); |
| allow_drain = false; |
| } |
| |
| if (isolate_lru_page(page)) { |
| if (remap) { |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| migrate->cpages--; |
| restore++; |
| } else { |
| migrate->src[i] = 0; |
| unlock_page(page); |
| migrate->cpages--; |
| put_page(page); |
| } |
| continue; |
| } |
| |
| /* Drop the reference we took in collect */ |
| put_page(page); |
| } |
| |
| if (!migrate_vma_check_page(page)) { |
| if (remap) { |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| migrate->cpages--; |
| restore++; |
| |
| if (!is_zone_device_page(page)) { |
| get_page(page); |
| putback_lru_page(page); |
| } |
| } else { |
| migrate->src[i] = 0; |
| unlock_page(page); |
| migrate->cpages--; |
| |
| if (!is_zone_device_page(page)) |
| putback_lru_page(page); |
| else |
| put_page(page); |
| } |
| } |
| } |
| |
| for (i = 0, addr = start; i < npages && restore; i++, addr += PAGE_SIZE) { |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| |
| if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) |
| continue; |
| |
| remove_migration_pte(page, migrate->vma, addr, page); |
| |
| migrate->src[i] = 0; |
| unlock_page(page); |
| put_page(page); |
| restore--; |
| } |
| } |
| |
| /* |
| * migrate_vma_unmap() - replace page mapping with special migration pte entry |
| * @migrate: migrate struct containing all migration information |
| * |
| * Replace page mapping (CPU page table pte) with a special migration pte entry |
| * and check again if it has been pinned. Pinned pages are restored because we |
| * cannot migrate them. |
| * |
| * This is the last step before we call the device driver callback to allocate |
| * destination memory and copy contents of original page over to new page. |
| */ |
| static void migrate_vma_unmap(struct migrate_vma *migrate) |
| { |
| int flags = TTU_MIGRATION | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; |
| const unsigned long npages = migrate->npages; |
| const unsigned long start = migrate->start; |
| unsigned long addr, i, restore = 0; |
| |
| for (i = 0; i < npages; i++) { |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| |
| if (!page || !(migrate->src[i] & MIGRATE_PFN_MIGRATE)) |
| continue; |
| |
| if (page_mapped(page)) { |
| try_to_unmap(page, flags); |
| if (page_mapped(page)) |
| goto restore; |
| } |
| |
| if (migrate_vma_check_page(page)) |
| continue; |
| |
| restore: |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| migrate->cpages--; |
| restore++; |
| } |
| |
| for (addr = start, i = 0; i < npages && restore; addr += PAGE_SIZE, i++) { |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| |
| if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) |
| continue; |
| |
| remove_migration_ptes(page, page, false); |
| |
| migrate->src[i] = 0; |
| unlock_page(page); |
| restore--; |
| |
| if (is_zone_device_page(page)) |
| put_page(page); |
| else |
| putback_lru_page(page); |
| } |
| } |
| |
| static void migrate_vma_insert_page(struct migrate_vma *migrate, |
| unsigned long addr, |
| struct page *page, |
| unsigned long *src, |
| unsigned long *dst) |
| { |
| struct vm_area_struct *vma = migrate->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| struct mem_cgroup *memcg; |
| bool flush = false; |
| spinlock_t *ptl; |
| pte_t entry; |
| pgd_t *pgdp; |
| p4d_t *p4dp; |
| pud_t *pudp; |
| pmd_t *pmdp; |
| pte_t *ptep; |
| |
| /* Only allow populating anonymous memory */ |
| if (!vma_is_anonymous(vma)) |
| goto abort; |
| |
| pgdp = pgd_offset(mm, addr); |
| p4dp = p4d_alloc(mm, pgdp, addr); |
| if (!p4dp) |
| goto abort; |
| pudp = pud_alloc(mm, p4dp, addr); |
| if (!pudp) |
| goto abort; |
| pmdp = pmd_alloc(mm, pudp, addr); |
| if (!pmdp) |
| goto abort; |
| |
| if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp)) |
| goto abort; |
| |
| /* |
| * Use pte_alloc() instead of pte_alloc_map(). We can't run |
| * pte_offset_map() on pmds where a huge pmd might be created |
| * from a different thread. |
| * |
| * pte_alloc_map() is safe to use under down_write(mmap_sem) or when |
| * parallel threads are excluded by other means. |
| * |
| * Here we only have down_read(mmap_sem). |
| */ |
| if (pte_alloc(mm, pmdp, addr)) |
| goto abort; |
| |
| /* See the comment in pte_alloc_one_map() */ |
| if (unlikely(pmd_trans_unstable(pmdp))) |
| goto abort; |
| |
| if (unlikely(anon_vma_prepare(vma))) |
| goto abort; |
| if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false)) |
| goto abort; |
| |
| /* |
| * The memory barrier inside __SetPageUptodate makes sure that |
| * preceding stores to the page contents become visible before |
| * the set_pte_at() write. |
| */ |
| __SetPageUptodate(page); |
| |
| if (is_zone_device_page(page)) { |
| if (is_device_private_page(page)) { |
| swp_entry_t swp_entry; |
| |
| swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE); |
| entry = swp_entry_to_pte(swp_entry); |
| } else if (is_device_public_page(page)) { |
| entry = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); |
| if (vma->vm_flags & VM_WRITE) |
| entry = pte_mkwrite(pte_mkdirty(entry)); |
| entry = pte_mkdevmap(entry); |
| } |
| } else { |
| entry = mk_pte(page, vma->vm_page_prot); |
| if (vma->vm_flags & VM_WRITE) |
| entry = pte_mkwrite(pte_mkdirty(entry)); |
| } |
| |
| ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); |
| |
| if (pte_present(*ptep)) { |
| unsigned long pfn = pte_pfn(*ptep); |
| |
| if (!is_zero_pfn(pfn)) { |
| pte_unmap_unlock(ptep, ptl); |
| mem_cgroup_cancel_charge(page, memcg, false); |
| goto abort; |
| } |
| flush = true; |
| } else if (!pte_none(*ptep)) { |
| pte_unmap_unlock(ptep, ptl); |
| mem_cgroup_cancel_charge(page, memcg, false); |
| goto abort; |
| } |
| |
| /* |
| * Check for usefaultfd but do not deliver the fault. Instead, |
| * just back off. |
| */ |
| if (userfaultfd_missing(vma)) { |
| pte_unmap_unlock(ptep, ptl); |
| mem_cgroup_cancel_charge(page, memcg, false); |
| goto abort; |
| } |
| |
| inc_mm_counter(mm, MM_ANONPAGES); |
| page_add_new_anon_rmap(page, vma, addr, false); |
| mem_cgroup_commit_charge(page, memcg, false, false); |
| if (!is_zone_device_page(page)) |
| lru_cache_add_active_or_unevictable(page, vma); |
| get_page(page); |
| |
| if (flush) { |
| flush_cache_page(vma, addr, pte_pfn(*ptep)); |
| ptep_clear_flush_notify(vma, addr, ptep); |
| set_pte_at_notify(mm, addr, ptep, entry); |
| update_mmu_cache(vma, addr, ptep); |
| } else { |
| /* No need to invalidate - it was non-present before */ |
| set_pte_at(mm, addr, ptep, entry); |
| update_mmu_cache(vma, addr, ptep); |
| } |
| |
| pte_unmap_unlock(ptep, ptl); |
| *src = MIGRATE_PFN_MIGRATE; |
| return; |
| |
| abort: |
| *src &= ~MIGRATE_PFN_MIGRATE; |
| } |
| |
| /* |
| * migrate_vma_pages() - migrate meta-data from src page to dst page |
| * @migrate: migrate struct containing all migration information |
| * |
| * This migrates struct page meta-data from source struct page to destination |
| * struct page. This effectively finishes the migration from source page to the |
| * destination page. |
| */ |
| static void migrate_vma_pages(struct migrate_vma *migrate) |
| { |
| const unsigned long npages = migrate->npages; |
| const unsigned long start = migrate->start; |
| struct vm_area_struct *vma = migrate->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long addr, i, mmu_start; |
| bool notified = false; |
| |
| for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) { |
| struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| struct address_space *mapping; |
| int r; |
| |
| if (!newpage) { |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| continue; |
| } |
| |
| if (!page) { |
| if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) { |
| continue; |
| } |
| if (!notified) { |
| mmu_start = addr; |
| notified = true; |
| mmu_notifier_invalidate_range_start(mm, |
| mmu_start, |
| migrate->end); |
| } |
| migrate_vma_insert_page(migrate, addr, newpage, |
| &migrate->src[i], |
| &migrate->dst[i]); |
| continue; |
| } |
| |
| mapping = page_mapping(page); |
| |
| if (is_zone_device_page(newpage)) { |
| if (is_device_private_page(newpage)) { |
| /* |
| * For now only support private anonymous when |
| * migrating to un-addressable device memory. |
| */ |
| if (mapping) { |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| continue; |
| } |
| } else if (!is_device_public_page(newpage)) { |
| /* |
| * Other types of ZONE_DEVICE page are not |
| * supported. |
| */ |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| continue; |
| } |
| } |
| |
| r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY); |
| if (r != MIGRATEPAGE_SUCCESS) |
| migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
| } |
| |
| if (notified) |
| mmu_notifier_invalidate_range_end(mm, mmu_start, |
| migrate->end); |
| } |
| |
| /* |
| * migrate_vma_finalize() - restore CPU page table entry |
| * @migrate: migrate struct containing all migration information |
| * |
| * This replaces the special migration pte entry with either a mapping to the |
| * new page if migration was successful for that page, or to the original page |
| * otherwise. |
| * |
| * This also unlocks the pages and puts them back on the lru, or drops the extra |
| * refcount, for device pages. |
| */ |
| static void migrate_vma_finalize(struct migrate_vma *migrate) |
| { |
| const unsigned long npages = migrate->npages; |
| unsigned long i; |
| |
| for (i = 0; i < npages; i++) { |
| struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); |
| struct page *page = migrate_pfn_to_page(migrate->src[i]); |
| |
| if (!page) { |
| if (newpage) { |
| unlock_page(newpage); |
| put_page(newpage); |
| } |
| continue; |
| } |
| |
| if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE) || !newpage) { |
| if (newpage) { |
| unlock_page(newpage); |
| put_page(newpage); |
| } |
| newpage = page; |
| } |
| |
| remove_migration_ptes(page, newpage, false); |
| unlock_page(page); |
| migrate->cpages--; |
| |
| if (is_zone_device_page(page)) |
| put_page(page); |
| else |
| putback_lru_page(page); |
| |
| if (newpage != page) { |
| unlock_page(newpage); |
| if (is_zone_device_page(newpage)) |
| put_page(newpage); |
| else |
| putback_lru_page(newpage); |
| } |
| } |
| } |
| |
| /* |
| * migrate_vma() - migrate a range of memory inside vma |
| * |
| * @ops: migration callback for allocating destination memory and copying |
| * @vma: virtual memory area containing the range to be migrated |
| * @start: start address of the range to migrate (inclusive) |
| * @end: end address of the range to migrate (exclusive) |
| * @src: array of hmm_pfn_t containing source pfns |
| * @dst: array of hmm_pfn_t containing destination pfns |
| * @private: pointer passed back to each of the callback |
| * Returns: 0 on success, error code otherwise |
| * |
| * This function tries to migrate a range of memory virtual address range, using |
| * callbacks to allocate and copy memory from source to destination. First it |
| * collects all the pages backing each virtual address in the range, saving this |
| * inside the src array. Then it locks those pages and unmaps them. Once the pages |
| * are locked and unmapped, it checks whether each page is pinned or not. Pages |
| * that aren't pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) |
| * in the corresponding src array entry. It then restores any pages that are |
| * pinned, by remapping and unlocking those pages. |
| * |
| * At this point it calls the alloc_and_copy() callback. For documentation on |
| * what is expected from that callback, see struct migrate_vma_ops comments in |
| * include/linux/migrate.h |
| * |
| * After the alloc_and_copy() callback, this function goes over each entry in |
| * the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag |
| * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set, |
| * then the function tries to migrate struct page information from the source |
| * struct page to the destination struct page. If it fails to migrate the struct |
| * page information, then it clears the MIGRATE_PFN_MIGRATE flag in the src |
| * array. |
| * |
| * At this point all successfully migrated pages have an entry in the src |
| * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst |
| * array entry with MIGRATE_PFN_VALID flag set. |
| * |
| * It then calls the finalize_and_map() callback. See comments for "struct |
| * migrate_vma_ops", in include/linux/migrate.h for details about |
| * finalize_and_map() behavior. |
| * |
| * After the finalize_and_map() callback, for successfully migrated pages, this |
| * function updates the CPU page table to point to new pages, otherwise it |
| * restores the CPU page table to point to the original source pages. |
| * |
| * Function returns 0 after the above steps, even if no pages were migrated |
| * (The function only returns an error if any of the arguments are invalid.) |
| * |
| * Both src and dst array must be big enough for (end - start) >> PAGE_SHIFT |
| * unsigned long entries. |
| */ |
| int migrate_vma(const struct migrate_vma_ops *ops, |
| struct vm_area_struct *vma, |
| unsigned long start, |
| unsigned long end, |
| unsigned long *src, |
| unsigned long *dst, |
| void *private) |
| { |
| struct migrate_vma migrate; |
| |
| /* Sanity check the arguments */ |
| start &= PAGE_MASK; |
| end &= PAGE_MASK; |
| if (!vma || is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) |
| return -EINVAL; |
| if (start < vma->vm_start || start >= vma->vm_end) |
| return -EINVAL; |
| if (end <= vma->vm_start || end > vma->vm_end) |
| return -EINVAL; |
| if (!ops || !src || !dst || start >= end) |
| return -EINVAL; |
| |
| memset(src, 0, sizeof(*src) * ((end - start) >> PAGE_SHIFT)); |
| migrate.src = src; |
| migrate.dst = dst; |
| migrate.start = start; |
| migrate.npages = 0; |
| migrate.cpages = 0; |
| migrate.end = end; |
| migrate.vma = vma; |
| |
| /* Collect, and try to unmap source pages */ |
| migrate_vma_collect(&migrate); |
| if (!migrate.cpages) |
| return 0; |
| |
| /* Lock and isolate page */ |
| migrate_vma_prepare(&migrate); |
| if (!migrate.cpages) |
| return 0; |
| |
| /* Unmap pages */ |
| migrate_vma_unmap(&migrate); |
| if (!migrate.cpages) |
| return 0; |
| |
| /* |
| * At this point pages are locked and unmapped, and thus they have |
| * stable content and can safely be copied to destination memory that |
| * is allocated by the callback. |
| * |
| * Note that migration can fail in migrate_vma_struct_page() for each |
| * individual page. |
| */ |
| ops->alloc_and_copy(vma, src, dst, start, end, private); |
| |
| /* This does the real migration of struct page */ |
| migrate_vma_pages(&migrate); |
| |
| ops->finalize_and_map(vma, src, dst, start, end, private); |
| |
| /* Unlock and remap pages */ |
| migrate_vma_finalize(&migrate); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(migrate_vma); |
| #endif /* defined(MIGRATE_VMA_HELPER) */ |