1 files changed, 687 insertions, 371 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 1c25040693d2..1c2a71aa05cd 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -15,6 +15,7 @@
 #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>
@@ -23,13 +24,13 @@
 #include <linux/topology.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
-#include <linux/swapops.h>
+#include <linux/writeback.h>
+#include <linux/mempolicy.h>
+#include <linux/vmalloc.h>
+#include <linux/security.h>
 
 #include "internal.h"
 
-/* The maximum number of pages to take off the LRU for migration */
-#define MIGRATE_CHUNK_SIZE 256
-
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
 
 /*
@@ -64,16 +65,11 @@ int isolate_lru_page(struct page *page, struct list_head *pagelist)
 }
 
 /*
- * migrate_prep() needs to be called after we have compiled the list of pages
- * to be migrated using isolate_lru_page() but before we begin a series of calls
- * to migrate_pages().
+ * 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)
 {
-        /* Must have swap device for migration */
-        if (nr_swap_pages <= 0)
-                return -ENODEV;
-
         /*
          * Clear the LRU lists so pages can be isolated.
          * Note that pages may be moved off the LRU after we have
@@ -87,7 +83,6 @@ int migrate_prep(void)
 
 static inline void move_to_lru(struct page *page)
 {
-        list_del(&page->lru);
         if (PageActive(page)) {
                 /*
                  * lru_cache_add_active checks that
@@ -113,113 +108,200 @@ int putback_lru_pages(struct list_head *l)
         int count = 0;
 
         list_for_each_entry_safe(page, page2, l, lru) {
+                list_del(&page->lru);
                 move_to_lru(page);
                 count++;
         }
         return count;
 }
 
-/*
- * Non migratable page
- */
-int fail_migrate_page(struct page *newpage, struct page *page)
+static inline int is_swap_pte(pte_t pte)
 {
-        return -EIO;
+        return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
 }
-EXPORT_SYMBOL(fail_migrate_page);
 
 /*
- * swapout a single page
- * page is locked upon entry, unlocked on exit
+ * Restore a potential migration pte to a working pte entry
  */
-static int swap_page(struct page *page)
+static void remove_migration_pte(struct vm_area_struct *vma,
+                struct page *old, struct page *new)
 {
-        struct address_space *mapping = page_mapping(page);
+        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;
+        }
 
-        if (page_mapped(page) && mapping)
-                if (try_to_unmap(page, 1) != SWAP_SUCCESS)
-                        goto unlock_retry;
+        ptl = pte_lockptr(mm, pmd);
+        spin_lock(ptl);
+        pte = *ptep;
+        if (!is_swap_pte(pte))
+                goto out;
 
-        if (PageDirty(page)) {
-                /* Page is dirty, try to write it out here */
-                switch(pageout(page, mapping)) {
-                case PAGE_KEEP:
-                case PAGE_ACTIVATE:
-                        goto unlock_retry;
+        entry = pte_to_swp_entry(pte);
 
-                case PAGE_SUCCESS:
-                        goto retry;
+        if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
+                goto out;
 
-                case PAGE_CLEAN:
-                        ; /* try to free the page below */
-                }
-        }
+        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 (PagePrivate(page)) {
-                if (!try_to_release_page(page, GFP_KERNEL) ||
-                    (!mapping && page_count(page) == 1))
-                        goto unlock_retry;
-        }
+        if (PageAnon(new))
+                page_add_anon_rmap(new, vma, addr);
+        else
+                page_add_file_rmap(new);
 
-        if (remove_mapping(mapping, page)) {
-                /* Success */
-                unlock_page(page);
-                return 0;
-        }
+        /* No need to invalidate - it was non-present before */
+        update_mmu_cache(vma, addr, pte);
+        lazy_mmu_prot_update(pte);
 
-unlock_retry:
-        unlock_page(page);
+out:
+        pte_unmap_unlock(ptep, ptl);
+}
 
-retry:
-        return -EAGAIN;
+/*
+ * 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);
 }
 
 /*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
+ * Must hold mmap_sem lock on at least one of the vmas containing
+ * the page so that the anon_vma cannot vanish.
  */
-int migrate_page_remove_references(struct page *newpage,
-                                struct page *page, int nr_refs)
+static void remove_anon_migration_ptes(struct page *old, struct page *new)
 {
-        struct address_space *mapping = page_mapping(page);
-        struct page **radix_pointer;
+        struct anon_vma *anon_vma;
+        struct vm_area_struct *vma;
+        unsigned long mapping;
 
-        /*
-         * Avoid doing any of the following work if the page count
-         * indicates that the page is in use or truncate has removed
-         * the page.
-         */
-        if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
-                return -EAGAIN;
+        mapping = (unsigned long)new->mapping;
 
-        /*
-         * Establish swap ptes for anonymous pages or destroy pte
-         * maps for files.
-         *
-         * In order to reestablish file backed mappings the fault handlers
-         * will take the radix tree_lock which may then be used to stop
-         * processses from accessing this page until the new page is ready.
-         *
-         * A process accessing via a swap pte (an anonymous page) will take a
-         * page_lock on the old page which will block the process until the
-         * migration attempt is complete. At that time the PageSwapCache bit
-         * will be examined. If the page was migrated then the PageSwapCache
-         * bit will be clear and the operation to retrieve the page will be
-         * retried which will find the new page in the radix tree. Then a new
-         * direct mapping may be generated based on the radix tree contents.
-         *
-         * If the page was not migrated then the PageSwapCache bit
-         * is still set and the operation may continue.
-         */
-        if (try_to_unmap(page, 1) == SWAP_FAIL)
-                /* A vma has VM_LOCKED set -> permanent failure */
-                return -EPERM;
+        if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
+                return;
 
         /*
-         * Give up if we were unable to remove all mappings.
+         * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
          */
-        if (page_mapcount(page))
-                return -EAGAIN;
+        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)
+{
+        struct page **radix_pointer;
+
+        if (!mapping) {
+                /* Anonymous page */
+                if (page_count(page) != 1)
+                        return -EAGAIN;
+                return 0;
+        }
 
         write_lock_irq(&mapping->tree_lock);
 
@@ -227,7 +309,7 @@ int migrate_page_remove_references(struct page *newpage,
                                                 &mapping->page_tree,
                                                 page_index(page));
 
-        if (!page_mapping(page) || page_count(page) != nr_refs ||
+        if (page_count(page) != 2 + !!PagePrivate(page) ||
                         *radix_pointer != page) {
                 write_unlock_irq(&mapping->tree_lock);
                 return -EAGAIN;
@@ -235,19 +317,14 @@ int migrate_page_remove_references(struct page *newpage,
 
         /*
          * Now we know that no one else is looking at the page.
-         *
-         * Certain minimal information about a page must be available
-         * in order for other subsystems to properly handle the page if they
-         * find it through the radix tree update before we are finished
-         * copying the page.
          */
         get_page(newpage);
-        newpage->index = page->index;
-        newpage->mapping = page->mapping;
+#ifdef CONFIG_SWAP
         if (PageSwapCache(page)) {
                 SetPageSwapCache(newpage);
                 set_page_private(newpage, page_private(page));
         }
+#endif
 
         *radix_pointer = newpage;
         __put_page(page);
@@ -255,12 +332,11 @@ int migrate_page_remove_references(struct page *newpage,
 
         return 0;
 }
-EXPORT_SYMBOL(migrate_page_remove_references);
 
 /*
  * Copy the page to its new location
  */
-void migrate_page_copy(struct page *newpage, struct page *page)
+static void migrate_page_copy(struct page *newpage, struct page *page)
 {
         copy_highpage(newpage, page);
 
@@ -282,7 +358,9 @@ void migrate_page_copy(struct page *newpage, struct page *page)
                 set_page_dirty(newpage);
         }
 
+#ifdef CONFIG_SWAP
         ClearPageSwapCache(page);
+#endif
         ClearPageActive(page);
         ClearPagePrivate(page);
         set_page_private(page, 0);
@@ -295,7 +373,18 @@ void migrate_page_copy(struct page *newpage, struct page *page)
         if (PageWriteback(newpage))
                 end_page_writeback(newpage);
 }
-EXPORT_SYMBOL(migrate_page_copy);
+
+/************************************************************
+ *                    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
@@ -303,51 +392,286 @@ EXPORT_SYMBOL(migrate_page_copy);
  *
  * Pages are locked upon entry and exit.
  */
-int migrate_page(struct page *newpage, struct page *page)
+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_remove_references(newpage, page, 2);
+        rc = migrate_page_move_mapping(mapping, newpage, page);
+
+        if (rc)
+                return rc;
+
+        migrate_page_copy(newpage, page);
+        return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
+/*
+ * 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);
+
+/*
+ * 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,
+                .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;
+
         /*
-         * Remove auxiliary swap entries and replace
-         * them with real ptes.
-         *
-         * Note that a real pte entry will allow processes that are not
-         * waiting on the page lock to use the new page via the page tables
-         * before the new page is unlocked.
+         * 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_from_swap(newpage);
-        return 0;
+        remove_migration_ptes(page, page);
+
+        rc = mapping->a_ops->writepage(page, &wbc);
+        if (rc < 0)
+                /* I/O Error writing */
+                return -EIO;
+
+        if (rc != AOP_WRITEPAGE_ACTIVATE)
+                /* unlocked. Relock */
+                lock_page(page);
+
+        return -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)
+{
+        if (PageDirty(page))
+                return writeout(mapping, page);
+
+        /*
+         * Buffers may be managed in a filesystem specific way.
+         * We must have no buffers or drop them.
+         */
+        if (page_has_buffers(page) &&
+            !try_to_release_page(page, GFP_KERNEL))
+                return -EAGAIN;
+
+        return migrate_page(mapping, newpage, page);
+}
+
+/*
+ * 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.
+ */
+static int move_to_new_page(struct page *newpage, struct page *page)
+{
+        struct address_space *mapping;
+        int rc;
+
+        /*
+         * Block others from accessing the page when we get around to
+         * establishing additional references. We are the only one
+         * holding a reference to the new page at this point.
+         */
+        if (TestSetPageLocked(newpage))
+                BUG();
+
+        /* Prepare mapping for the new page.*/
+        newpage->index = page->index;
+        newpage->mapping = page->mapping;
+
+        mapping = page_mapping(page);
+        if (!mapping)
+                rc = migrate_page(mapping, newpage, page);
+        else if (mapping->a_ops->migratepage)
+                /*
+                 * Most pages have a mapping and most filesystems
+                 * should provide a migration function. Anonymous
+                 * pages are part of swap space which also has its
+                 * own migration function. This is the most common
+                 * path for page migration.
+                 */
+                rc = mapping->a_ops->migratepage(mapping,
+                                                newpage, page);
+        else
+                rc = fallback_migrate_page(mapping, newpage, page);
+
+        if (!rc)
+                remove_migration_ptes(page, newpage);
+        else
+                newpage->mapping = NULL;
+
+        unlock_page(newpage);
+
+        return rc;
+}
+
+/*
+ * Obtain the lock on page, remove all ptes and migrate the page
+ * to the newly allocated page in newpage.
+ */
+static int unmap_and_move(new_page_t get_new_page, unsigned long private,
+                        struct page *page, int force)
+{
+        int rc = 0;
+        int *result = NULL;
+        struct page *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. */
+                goto move_newpage;
+
+        rc = -EAGAIN;
+        if (TestSetPageLocked(page)) {
+                if (!force)
+                        goto move_newpage;
+                lock_page(page);
+        }
+
+        if (PageWriteback(page)) {
+                if (!force)
+                        goto unlock;
+                wait_on_page_writeback(page);
+        }
+
+        /*
+         * Establish migration ptes or remove ptes
+         */
+        if (try_to_unmap(page, 1) != SWAP_FAIL) {
+                if (!page_mapped(page))
+                        rc = move_to_new_page(newpage, page);
+        } else
+                /* A vma has VM_LOCKED set -> permanent failure */
+                rc = -EPERM;
+
+        if (rc)
+                remove_migration_ptes(page, page);
+unlock:
+        unlock_page(page);
+
+        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);
+                move_to_lru(page);
+        }
+
+move_newpage:
+        /*
+         * Move the new page to the LRU. If migration was not successful
+         * then this will free the page.
+         */
+        move_to_lru(newpage);
+        if (result) {
+                if (rc)
+                        *result = rc;
+                else
+                        *result = page_to_nid(newpage);
+        }
+        return rc;
 }
-EXPORT_SYMBOL(migrate_page);
 
 /*
  * migrate_pages
  *
- * Two lists are passed to this function. The first list
- * contains the pages isolated from the LRU to be migrated.
- * The second list contains new pages that the pages isolated
- * can be moved to. If the second list is NULL then all
- * pages are swapped out.
+ * The function takes one list of pages to migrate and a function
+ * that determines from the page to be migrated and the private data
+ * the target of the move and allocates the page.
  *
  * The function returns after 10 attempts or if no pages
  * are movable anymore because to has become empty
- * or no retryable pages exist anymore.
+ * or no retryable pages exist anymore. All pages will be
+ * retruned to the LRU or freed.
  *
- * Return: Number of pages not migrated when "to" ran empty.
+ * Return: Number of pages not migrated or error code.
  */
-int migrate_pages(struct list_head *from, struct list_head *to,
-                  struct list_head *moved, struct list_head *failed)
+int migrate_pages(struct list_head *from,
+                new_page_t get_new_page, unsigned long private)
 {
-        int retry;
+        int retry = 1;
         int nr_failed = 0;
         int pass = 0;
         struct page *page;
@@ -358,305 +682,297 @@ int migrate_pages(struct list_head *from, struct list_head *to,
         if (!swapwrite)
                 current->flags |= PF_SWAPWRITE;
 
-redo:
-        retry = 0;
+        for(pass = 0; pass < 10 && retry; pass++) {
+                retry = 0;
+
+                list_for_each_entry_safe(page, page2, from, lru) {
+                        cond_resched();
+
+                        rc = unmap_and_move(get_new_page, private,
+                                                page, pass > 2);
+
+                        switch(rc) {
+                        case -ENOMEM:
+                                goto out;
+                        case -EAGAIN:
+                                retry++;
+                                break;
+                        case 0:
+                                break;
+                        default:
+                                /* Permanent failure */
+                                nr_failed++;
+                                break;
+                        }
+                }
+        }
+        rc = 0;
+out:
+        if (!swapwrite)
+                current->flags &= ~PF_SWAPWRITE;
 
-        list_for_each_entry_safe(page, page2, from, lru) {
-                struct page *newpage = NULL;
-                struct address_space *mapping;
+        putback_lru_pages(from);
 
-                cond_resched();
+        if (rc)
+                return rc;
 
-                rc = 0;
-                if (page_count(page) == 1)
-                        /* page was freed from under us. So we are done. */
-                        goto next;
+        return nr_failed + retry;
+}
 
-                if (to && list_empty(to))
-                        break;
+#ifdef CONFIG_NUMA
+/*
+ * Move a list of individual pages
+ */
+struct page_to_node {
+        unsigned long addr;
+        struct page *page;
+        int node;
+        int status;
+};
 
-                /*
-                 * Skip locked pages during the first two passes to give the
-                 * functions holding the lock time to release the page. Later we
-                 * use lock_page() to have a higher chance of acquiring the
-                 * lock.
-                 */
-                rc = -EAGAIN;
-                if (pass > 2)
-                        lock_page(page);
-                else
-                        if (TestSetPageLocked(page))
-                                goto next;
+static struct page *new_page_node(struct page *p, unsigned long private,
+                int **result)
+{
+        struct page_to_node *pm = (struct page_to_node *)private;
 
-                /*
-                 * Only wait on writeback if we have already done a pass where
-                 * we we may have triggered writeouts for lots of pages.
-                 */
-                if (pass > 0) {
-                        wait_on_page_writeback(page);
-                } else {
-                        if (PageWriteback(page))
-                                goto unlock_page;
-                }
+        while (pm->node != MAX_NUMNODES && pm->page != p)
+                pm++;
 
-                /*
-                 * Anonymous pages must have swap cache references otherwise
-                 * the information contained in the page maps cannot be
-                 * preserved.
-                 */
-                if (PageAnon(page) && !PageSwapCache(page)) {
-                        if (!add_to_swap(page, GFP_KERNEL)) {
-                                rc = -ENOMEM;
-                                goto unlock_page;
-                        }
-                }
+        if (pm->node == MAX_NUMNODES)
+                return NULL;
 
-                if (!to) {
-                        rc = swap_page(page);
-                        goto next;
-                }
+        *result = &pm->status;
 
-                newpage = lru_to_page(to);
-                lock_page(newpage);
+        return alloc_pages_node(pm->node, GFP_HIGHUSER, 0);
+}
 
-                /*
-                 * Pages are properly locked and writeback is complete.
-                 * Try to migrate the page.
-                 */
-                mapping = page_mapping(page);
-                if (!mapping)
-                        goto unlock_both;
+/*
+ * 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.
+ */
+static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
+                                int migrate_all)
+{
+        int err;
+        struct page_to_node *pp;
+        LIST_HEAD(pagelist);
 
-                if (mapping->a_ops->migratepage) {
-                        /*
-                         * Most pages have a mapping and most filesystems
-                         * should provide a migration function. Anonymous
-                         * pages are part of swap space which also has its
-                         * own migration function. This is the most common
-                         * path for page migration.
-                         */
-                        rc = mapping->a_ops->migratepage(newpage, page);
-                        goto unlock_both;
-                }
-
-                /* Make sure the dirty bit is up to date */
-                if (try_to_unmap(page, 1) == SWAP_FAIL) {
-                        rc = -EPERM;
-                        goto unlock_both;
-                }
+        down_read(&mm->mmap_sem);
 
-                if (page_mapcount(page)) {
-                        rc = -EAGAIN;
-                        goto unlock_both;
-                }
+        /*
+         * Build a list of pages to migrate
+         */
+        migrate_prep();
+        for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
+                struct vm_area_struct *vma;
+                struct page *page;
 
                 /*
-                 * Default handling if a filesystem does not provide
-                 * a migration function. We can only migrate clean
-                 * pages so try to write out any dirty pages first.
+                 * A valid page pointer that will not match any of the
+                 * pages that will be moved.
                  */
-                if (PageDirty(page)) {
-                        switch (pageout(page, mapping)) {
-                        case PAGE_KEEP:
-                        case PAGE_ACTIVATE:
-                                goto unlock_both;
-
-                        case PAGE_SUCCESS:
-                                unlock_page(newpage);
-                                goto next;
-
-                        case PAGE_CLEAN:
-                                ; /* try to migrate the page below */
-                        }
-                }
+                pp->page = ZERO_PAGE(0);
 
-                /*
-                 * Buffers are managed in a filesystem specific way.
-                 * We must have no buffers or drop them.
-                 */
-                if (!page_has_buffers(page) ||
-                    try_to_release_page(page, GFP_KERNEL)) {
-                        rc = migrate_page(newpage, page);
-                        goto unlock_both;
-                }
+                err = -EFAULT;
+                vma = find_vma(mm, pp->addr);
+                if (!vma)
+                        goto set_status;
 
-                /*
-                 * On early passes with mapped pages simply
-                 * retry. There may be a lock held for some
-                 * buffers that may go away. Later
-                 * swap them out.
-                 */
-                if (pass > 4) {
+                page = follow_page(vma, pp->addr, FOLL_GET);
+                err = -ENOENT;
+                if (!page)
+                        goto set_status;
+
+                if (PageReserved(page))         /* Check for zero page */
+                        goto put_and_set;
+
+                pp->page = page;
+                err = page_to_nid(page);
+
+                if (err == pp->node)
                         /*
-                         * Persistently unable to drop buffers..... As a
-                         * measure of last resort we fall back to
-                         * swap_page().
+                         * Node already in the right place
                          */
-                        unlock_page(newpage);
-                        newpage = NULL;
-                        rc = swap_page(page);
-                        goto next;
-                }
+                        goto put_and_set;
 
-unlock_both:
-                unlock_page(newpage);
-
-unlock_page:
-                unlock_page(page);
-
-next:
-                if (rc == -EAGAIN) {
-                        retry++;
-                } else if (rc) {
-                        /* Permanent failure */
-                        list_move(&page->lru, failed);
-                        nr_failed++;
-                } else {
-                        if (newpage) {
-                                /* Successful migration. Return page to LRU */
-                                move_to_lru(newpage);
-                        }
-                        list_move(&page->lru, moved);
-                }
+                err = -EACCES;
+                if (page_mapcount(page) > 1 &&
+                                !migrate_all)
+                        goto put_and_set;
+
+                err = isolate_lru_page(page, &pagelist);
+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;
         }
-        if (retry && pass++ < 10)
-                goto redo;
 
-        if (!swapwrite)
-                current->flags &= ~PF_SWAPWRITE;
+        if (!list_empty(&pagelist))
+                err = migrate_pages(&pagelist, new_page_node,
+                                (unsigned long)pm);
+        else
+                err = -ENOENT;
 
-        return nr_failed + retry;
+        up_read(&mm->mmap_sem);
+        return err;
 }
 
 /*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
+ * Determine the nodes of a list of pages. The addr in the pm array
+ * must have been set to the virtual address of which we want to determine
+ * the node number.
  */
-int buffer_migrate_page(struct page *newpage, struct page *page)
+static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
 {
-        struct address_space *mapping = page->mapping;
-        struct buffer_head *bh, *head;
-        int rc;
+        down_read(&mm->mmap_sem);
+
+        for ( ; pm->node != MAX_NUMNODES; pm++) {
+                struct vm_area_struct *vma;
+                struct page *page;
+                int err;
+
+                err = -EFAULT;
+                vma = find_vma(mm, pm->addr);
+                if (!vma)
+                        goto set_status;
+
+                page = follow_page(vma, pm->addr, 0);
+                err = -ENOENT;
+                /* Use PageReserved to check for zero page */
+                if (!page || PageReserved(page))
+                        goto set_status;
+
+                err = page_to_nid(page);
+set_status:
+                pm->status = err;
+        }
 
-        if (!mapping)
-                return -EAGAIN;
+        up_read(&mm->mmap_sem);
+        return 0;
+}
 
-        if (!page_has_buffers(page))
-                return migrate_page(newpage, page);
+/*
+ * Move a list of pages in the address space of the currently executing
+ * process.
+ */
+asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
+                        const void __user * __user *pages,
+                        const int __user *nodes,
+                        int __user *status, int flags)
+{
+        int err = 0;
+        int i;
+        struct task_struct *task;
+        nodemask_t task_nodes;
+        struct mm_struct *mm;
+        struct page_to_node *pm = NULL;
 
-        head = page_buffers(page);
+        /* Check flags */
+        if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
+                return -EINVAL;
 
-        rc = migrate_page_remove_references(newpage, page, 3);
+        if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
+                return -EPERM;
 
-        if (rc)
-                return rc;
+        /* Find the mm_struct */
+        read_lock(&tasklist_lock);
+        task = pid ? find_task_by_pid(pid) : current;
+        if (!task) {
+                read_unlock(&tasklist_lock);
+                return -ESRCH;
+        }
+        mm = get_task_mm(task);
+        read_unlock(&tasklist_lock);
 
-        bh = head;
-        do {
-                get_bh(bh);
-                lock_buffer(bh);
-                bh = bh->b_this_page;
+        if (!mm)
+                return -EINVAL;
 
-        } while (bh != head);
+        /*
+         * Check if this process has the right to modify the specified
+         * process. The right exists if the process has administrative
+         * capabilities, superuser privileges or the same
+         * userid as the target process.
+         */
+        if ((current->euid != task->suid) && (current->euid != task->uid) &&
+            (current->uid != task->suid) && (current->uid != task->uid) &&
+            !capable(CAP_SYS_NICE)) {
+                err = -EPERM;
+                goto out2;
+        }
 
-        ClearPagePrivate(page);
-        set_page_private(newpage, page_private(page));
-        set_page_private(page, 0);
-        put_page(page);
-        get_page(newpage);
+        err = security_task_movememory(task);
+        if (err)
+                goto out2;
 
-        bh = head;
-        do {
-                set_bh_page(bh, newpage, bh_offset(bh));
-                bh = bh->b_this_page;
 
-        } while (bh != head);
+        task_nodes = cpuset_mems_allowed(task);
 
-        SetPagePrivate(newpage);
+        /* Limit nr_pages so that the multiplication may not overflow */
+        if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
+                err = -E2BIG;
+                goto out2;
+        }
 
-        migrate_page_copy(newpage, page);
+        pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
+        if (!pm) {
+                err = -ENOMEM;
+                goto out2;
+        }
 
-        bh = head;
-        do {
-                unlock_buffer(bh);
-                put_bh(bh);
-                bh = bh->b_this_page;
+        /*
+         * Get parameters from user space and initialize the pm
+         * array. Return various errors if the user did something wrong.
+         */
+        for (i = 0; i < nr_pages; i++) {
+                const void *p;
 
-        } while (bh != head);
+                err = -EFAULT;
+                if (get_user(p, pages + i))
+                        goto out;
 
-        return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
+                pm[i].addr = (unsigned long)p;
+                if (nodes) {
+                        int node;
 
-/*
- * Migrate the list 'pagelist' of pages to a certain destination.
- *
- * Specify destination with either non-NULL vma or dest_node >= 0
- * Return the number of pages not migrated or error code
- */
-int migrate_pages_to(struct list_head *pagelist,
-                        struct vm_area_struct *vma, int dest)
-{
-        LIST_HEAD(newlist);
-        LIST_HEAD(moved);
-        LIST_HEAD(failed);
-        int err = 0;
-        unsigned long offset = 0;
-        int nr_pages;
-        struct page *page;
-        struct list_head *p;
+                        if (get_user(node, nodes + i))
+                                goto out;
 
-redo:
-        nr_pages = 0;
-        list_for_each(p, pagelist) {
-                if (vma) {
-                        /*
-                         * The address passed to alloc_page_vma is used to
-                         * generate the proper interleave behavior. We fake
-                         * the address here by an increasing offset in order
-                         * to get the proper distribution of pages.
-                         *
-                         * No decision has been made as to which page
-                         * a certain old page is moved to so we cannot
-                         * specify the correct address.
-                         */
-                        page = alloc_page_vma(GFP_HIGHUSER, vma,
-                                        offset + vma->vm_start);
-                        offset += PAGE_SIZE;
-                }
-                else
-                        page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
+                        err = -ENODEV;
+                        if (!node_online(node))
+                                goto out;
 
-                if (!page) {
-                        err = -ENOMEM;
-                        goto out;
+                        err = -EACCES;
+                        if (!node_isset(node, task_nodes))
+                                goto out;
+
+                        pm[i].node = node;
                 }
-                list_add_tail(&page->lru, &newlist);
-                nr_pages++;
-                if (nr_pages > MIGRATE_CHUNK_SIZE)
-                        break;
         }
-        err = migrate_pages(pagelist, &newlist, &moved, &failed);
+        /* End marker */
+        pm[nr_pages].node = MAX_NUMNODES;
+
+        if (nodes)
+                err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
+        else
+                err = do_pages_stat(mm, pm);
 
-        putback_lru_pages(&moved);      /* Call release pages instead ?? */
+        if (err >= 0)
+                /* Return status information */
+                for (i = 0; i < nr_pages; i++)
+                        if (put_user(pm[i].status, status + i))
+                                err = -EFAULT;
 
-        if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
-                goto redo;
 out:
-        /* Return leftover allocated pages */
-        while (!list_empty(&newlist)) {
-                page = list_entry(newlist.next, struct page, lru);
-                list_del(&page->lru);
-                __free_page(page);
-        }
-        list_splice(&failed, pagelist);
-        if (err < 0)
-                return err;
-
-        /* Calculate number of leftover pages */
-        nr_pages = 0;
-        list_for_each(p, pagelist)
-                nr_pages++;
-        return nr_pages;
+        vfree(pm);
+out2:
+        mmput(mm);
+        return err;
 }
+#endif
+