/* * Memory Migration functionality - linux/mm/migration.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 <clameter@sgi.com> */ #include <linux/migrate.h>#include <linux/module.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/pagevec.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 "internal.h" #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) /* * Isolate one page from the LRU lists. If successful put it onto * the indicated list with elevated page count. * * Result: * -EBUSY: page not on LRU list * 0: page removed from LRU list and added to the specified list. */int isolate_lru_page(struct page *page, struct list_head *pagelist){ int ret = -EBUSY; if (PageLRU(page)) { struct zone *zone = page_zone(page); spin_lock_irq(&zone->lru_lock); if (PageLRU(page)) { ret = 0; get_page(page); ClearPageLRU(page); if (PageActive(page)) del_page_from_active_list(zone, page); else del_page_from_inactive_list(zone, page); list_add_tail(&page->lru, pagelist); } spin_unlock_irq(&zone->lru_lock); } return ret;} /* * migrate_prep() needs to be called before we start compiling a list of pages * to be migrated using isolate_lru_page(). */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;} static inline void move_to_lru(struct page *page){ if (PageActive(page)) { /* * lru_cache_add_active checks that * the PG_active bit is off. */ ClearPageActive(page); lru_cache_add_active(page); } else { lru_cache_add(page); } put_page(page);} /* * Add isolated pages on the list back to the LRU. * * returns the number of pages put back. */int putback_lru_pages(struct list_head *l){ struct page *page; struct page *page2; int count = 0; list_for_each_entry_safe(page, page2, l, lru) { list_del(&page->lru); move_to_lru(page); count++; } return count;} static inline int is_swap_pte(pte_t pte){ return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);} /* * Restore a potential migration pte to a working pte entry */static void remove_migration_pte(struct vm_area_struct *vma, struct page *old, struct page *new){ struct mm_struct *mm = vma->vm_mm; swp_entry_t entry; pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *ptep, pte; spinlock_t *ptl; unsigned long addr = page_address_in_vma(new, vma); if (addr == -EFAULT) return; pgd = pgd_offset(mm, addr); if (!pgd_present(*pgd)) return; pud = pud_offset(pgd, addr); if (!pud_present(*pud)) return; pmd = pmd_offset(pud, addr); if (!pmd_present(*pmd)) return; ptep = pte_offset_map(pmd, addr); if (!is_swap_pte(*ptep)) { pte_unmap(ptep); return; } ptl = pte_lockptr(mm, pmd); spin_lock(ptl); pte = *ptep; if (!is_swap_pte(pte)) goto out; entry = pte_to_swp_entry(pte); if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) goto out; get_page(new); pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); if (is_write_migration_entry(entry)) pte = pte_mkwrite(pte); set_pte_at(mm, addr, ptep, pte); if (PageAnon(new)) page_add_anon_rmap(new, vma, addr); else page_add_file_rmap(new); /* No need to invalidate - it was non-present before */ update_mmu_cache(vma, addr, pte); lazy_mmu_prot_update(pte); out: pte_unmap_unlock(ptep, ptl);} /* * Note that remove_file_migration_ptes will only work on regular mappings, * Nonlinear mappings do not use migration entries. */static void remove_file_migration_ptes(struct page *old, struct page *new){ struct vm_area_struct *vma; struct address_space *mapping = page_mapping(new); struct prio_tree_iter iter; pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); if (!mapping) return; spin_lock(&mapping->i_mmap_lock); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) remove_migration_pte(vma, old, new); spin_unlock(&mapping->i_mmap_lock);} /* * Must hold mmap_sem lock on at least one of the vmas containing * the page so that the anon_vma cannot vanish. */static void remove_anon_migration_ptes(struct page *old, struct page *new){ struct anon_vma *anon_vma; struct vm_area_struct *vma; unsigned long mapping; mapping = (unsigned long)new->mapping; if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) return; /* * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. */ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_migration_pte(vma, old, new); spin_unlock(&anon_vma->lock);} /* * Get rid of all migration entries and replace them by * references to the indicated page. */static void remove_migration_ptes(struct page *old, struct page *new){ if (PageAnon(new)) remove_anon_migration_ptes(old, new); else remove_file_migration_ptes(old, new);} /* * 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. * * This function is called from do_swap_page(). */void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, unsigned long address){ pte_t *ptep, pte; spinlock_t *ptl; swp_entry_t entry; struct page *page; ptep = pte_offset_map_lock(mm, pmd, address, &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); get_page(page); pte_unmap_unlock(ptep, ptl); wait_on_page_locked(page); put_page(page); return;out: pte_unmap_unlock(ptep, ptl);} /* * 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 set. */static int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page){ void **pslot; if (!mapping) { /* Anonymous page without mapping */ if (page_count(page) != 1) return -EAGAIN; return 0; } write_lock_irq(&mapping->tree_lock); pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); if (page_count(page) != 2 + !!PagePrivate(page) || (struct page *)radix_tree_deref_slot(pslot) != page) { write_unlock_irq(&mapping->tree_lock); return -EAGAIN; } /* * Now we know that no one else is looking at the page. */ get_page(newpage); /* add cache reference */#ifdef CONFIG_SWAP if (PageSwapCache(page)) { SetPageSwapCache(newpage); set_page_private(newpage, page_private(page)); }#endif radix_tree_replace_slot(pslot, newpage); /* * Drop cache reference from old page. * We know this isn't the last reference. */ __put_page(page); /* * 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_PAGES if they * are mapped to swap space. */ __dec_zone_page_state(page, NR_FILE_PAGES); __inc_zone_page_state(newpage, NR_FILE_PAGES); write_unlock_irq(&mapping->tree_lock); return 0;} /* * Copy the page to its new location */static void migrate_page_copy(struct page *newpage, struct page *page){ copy_highpage(newpage, page); if (PageError(page)) SetPageError(newpage); if (PageReferenced(page)) SetPageReferenced(newpage); if (PageUptodate(page)) SetPageUptodate(newpage); if (PageActive(page)) SetPageActive(newpage); if (PageChecked(page)) SetPageChecked(newpage); if (PageMappedToDisk(page)) SetPageMappedToDisk(newpage); if (PageDirty(page)) { clear_page_dirty_for_io(page); set_page_dirty(newpage); } #ifdef CONFIG_SWAP ClearPageSwapCache(page);#endif ClearPageActive(page); ClearPagePrivate(page); set_page_private(page, 0); page->mapping = NULL; /* * If any waiters have accumulated on the new page then * wake them up. */ if (PageWriteback(newpage)) end_page_writeback(newpage);} /************************************************************ * Migration functions ***********************************************************/ /* Always fail migration. Used for mappings that are not movable */int fail_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page){ return -EIO;}EXPORT_SYMBOL(fail_migrate_page); /* * Common logic to directly migrate a single page suitable for * pages that do not use PagePrivate. * * Pages are locked upon entry and exit. */int migrate_page(struct address_space *mapping, struct page *newpage, struct page *page){ int rc; BUG_ON(PageWriteback(page)); /* Writeback must be complete */ rc = migrate_page_move_mapping(mapping, newpage, page); if (rc) return rc; migrate_page_copy(newpage, page); return 0;}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){ struct buffer_head *bh, *head; int rc; if (!page_has_buffers(page)) return migrate_page(mapping, newpage, page); head = page_buffers(page); rc = migrate_page_move_mapping(mapping, newpage, page); if (rc) return rc; bh = head; do { get_bh(bh); lock_buffer(bh); bh = bh->b_this_page; } while (bh != head); 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); migrate_page_copy(newpage, page); bh = head; do { unlock_buffer(bh); put_bh(bh); bh = bh->b_this_page; } while (bh != head); return 0;}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, .nonblocking = 1,Lines 1–500 of 1017. 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/* * Memory Migration functionality - linux/mm/migration.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 <clameter@sgi.com> */ #include <linux/migrate.h> #include <linux/module.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/pagevec.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 "internal.h" #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) /* * Isolate one page from the LRU lists. If successful put it onto * the indicated list with elevated page count. * * Result: * -EBUSY: page not on LRU list * 0: page removed from LRU list and added to the specified list. */ int isolate_lru_page(struct page *page, struct list_head *pagelist) { int ret = -EBUSY; if (PageLRU(page)) { struct zone *zone = page_zone(page); spin_lock_irq(&zone->lru_lock); if (PageLRU(page)) { ret = 0; get_page(page); ClearPageLRU(page); if (PageActive(page)) del_page_from_active_list(zone, page); else del_page_from_inactive_list(zone, page); list_add_tail(&page->lru, pagelist); } spin_unlock_irq(&zone->lru_lock); } return ret; } /* * migrate_prep() needs to be called before we start compiling a list of pages * to be migrated using isolate_lru_page(). */ 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; } static inline void move_to_lru(struct page *page) { if (PageActive(page)) { /* * lru_cache_add_active checks that * the PG_active bit is off. */ ClearPageActive(page); lru_cache_add_active(page); } else { lru_cache_add(page); } put_page(page); } /* * Add isolated pages on the list back to the LRU. * * returns the number of pages put back. */ int putback_lru_pages(struct list_head *l) { struct page *page; struct page *page2; int count = 0; list_for_each_entry_safe(page, page2, l, lru) { list_del(&page->lru); move_to_lru(page); count++; } return count; } static inline int is_swap_pte(pte_t pte) { return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); } /* * Restore a potential migration pte to a working pte entry */ static void remove_migration_pte(struct vm_area_struct *vma, struct page *old, struct page *new) { struct mm_struct *mm = vma->vm_mm; swp_entry_t entry; pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *ptep, pte; spinlock_t *ptl; unsigned long addr = page_address_in_vma(new, vma); if (addr == -EFAULT) return; pgd = pgd_offset(mm, addr); if (!pgd_present(*pgd)) return; pud = pud_offset(pgd, addr); if (!pud_present(*pud)) return; pmd = pmd_offset(pud, addr); if (!pmd_present(*pmd)) return; ptep = pte_offset_map(pmd, addr); if (!is_swap_pte(*ptep)) { pte_unmap(ptep); return; } ptl = pte_lockptr(mm, pmd); spin_lock(ptl); pte = *ptep; if (!is_swap_pte(pte)) goto out; entry = pte_to_swp_entry(pte); if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old) goto out; get_page(new); pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); if (is_write_migration_entry(entry)) pte = pte_mkwrite(pte); set_pte_at(mm, addr, ptep, pte); if (PageAnon(new)) page_add_anon_rmap(new, vma, addr); else page_add_file_rmap(new); /* No need to invalidate - it was non-present before */ update_mmu_cache(vma, addr, pte); lazy_mmu_prot_update(pte); out: pte_unmap_unlock(ptep, ptl); } /* * Note that remove_file_migration_ptes will only work on regular mappings, * Nonlinear mappings do not use migration entries. */ static void remove_file_migration_ptes(struct page *old, struct page *new) { struct vm_area_struct *vma; struct address_space *mapping = page_mapping(new); struct prio_tree_iter iter; pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); if (!mapping) return; spin_lock(&mapping->i_mmap_lock); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) remove_migration_pte(vma, old, new); spin_unlock(&mapping->i_mmap_lock); } /* * Must hold mmap_sem lock on at least one of the vmas containing * the page so that the anon_vma cannot vanish. */ static void remove_anon_migration_ptes(struct page *old, struct page *new) { struct anon_vma *anon_vma; struct vm_area_struct *vma; unsigned long mapping; mapping = (unsigned long)new->mapping; if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) return; /* * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. */ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_migration_pte(vma, old, new); spin_unlock(&anon_vma->lock); } /* * Get rid of all migration entries and replace them by * references to the indicated page. */ static void remove_migration_ptes(struct page *old, struct page *new) { if (PageAnon(new)) remove_anon_migration_ptes(old, new); else remove_file_migration_ptes(old, new); } /* * 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. * * This function is called from do_swap_page(). */ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, unsigned long address) { pte_t *ptep, pte; spinlock_t *ptl; swp_entry_t entry; struct page *page; ptep = pte_offset_map_lock(mm, pmd, address, &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); get_page(page); pte_unmap_unlock(ptep, ptl); wait_on_page_locked(page); put_page(page); return; out: pte_unmap_unlock(ptep, ptl); } /* * 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 set. */ static int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page) { void **pslot; if (!mapping) { /* Anonymous page without mapping */ if (page_count(page) != 1) return -EAGAIN; return 0; } write_lock_irq(&mapping->tree_lock); pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); if (page_count(page) != 2 + !!PagePrivate(page) || (struct page *)radix_tree_deref_slot(pslot) != page) { write_unlock_irq(&mapping->tree_lock); return -EAGAIN; } /* * Now we know that no one else is looking at the page. */ get_page(newpage); /* add cache reference */ #ifdef CONFIG_SWAP if (PageSwapCache(page)) { SetPageSwapCache(newpage); set_page_private(newpage, page_private(page)); } #endif radix_tree_replace_slot(pslot, newpage); /* * Drop cache reference from old page. * We know this isn't the last reference. */ __put_page(page); /* * 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_PAGES if they * are mapped to swap space. */ __dec_zone_page_state(page, NR_FILE_PAGES); __inc_zone_page_state(newpage, NR_FILE_PAGES); write_unlock_irq(&mapping->tree_lock); return 0; } /* * Copy the page to its new location */ static void migrate_page_copy(struct page *newpage, struct page *page) { copy_highpage(newpage, page); if (PageError(page)) SetPageError(newpage); if (PageReferenced(page)) SetPageReferenced(newpage); if (PageUptodate(page)) SetPageUptodate(newpage); if (PageActive(page)) SetPageActive(newpage); if (PageChecked(page)) SetPageChecked(newpage); if (PageMappedToDisk(page)) SetPageMappedToDisk(newpage); if (PageDirty(page)) { clear_page_dirty_for_io(page); set_page_dirty(newpage); } #ifdef CONFIG_SWAP ClearPageSwapCache(page); #endif ClearPageActive(page); ClearPagePrivate(page); set_page_private(page, 0); page->mapping = NULL; /* * If any waiters have accumulated on the new page then * wake them up. */ if (PageWriteback(newpage)) end_page_writeback(newpage); } /************************************************************ * Migration functions ***********************************************************/ /* Always fail migration. Used for mappings that are not movable */ int fail_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page) { return -EIO; } EXPORT_SYMBOL(fail_migrate_page); /* * Common logic to directly migrate a single page suitable for * pages that do not use PagePrivate. * * Pages are locked upon entry and exit. */ int migrate_page(struct address_space *mapping, struct page *newpage, struct page *page) { int rc; BUG_ON(PageWriteback(page)); /* Writeback must be complete */ rc = migrate_page_move_mapping(mapping, newpage, page); if (rc) return rc; migrate_page_copy(newpage, page); return 0; } 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) { struct buffer_head *bh, *head; int rc; if (!page_has_buffers(page)) return migrate_page(mapping, newpage, page); head = page_buffers(page); rc = migrate_page_move_mapping(mapping, newpage, page); if (rc) return rc; bh = head; do { get_bh(bh); lock_buffer(bh); bh = bh->b_this_page; } while (bh != head); 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); migrate_page_copy(newpage, page); bh = head; do { unlock_buffer(bh); put_bh(bh); bh = bh->b_this_page; } while (bh != head); return 0; } 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, .nonblocking = 1,